//
//  GCDAsyncSocket.m
//  
//  This class is in the public domain.
//  Originally created by Robbie Hanson in Q4 2010.
//  Updated and maintained by Deusty LLC and the Apple development community.
//
//  https://github.com/robbiehanson/CocoaAsyncSocket
//

#import "GCDAsyncSocket.h"

#if TARGET_OS_IPHONE
#import <CFNetwork/CFNetwork.h>
#endif

#import <arpa/inet.h>
#import <fcntl.h>
#import <ifaddrs.h>
#import <netdb.h>
#import <netinet/in.h>
#import <net/if.h>
#import <sys/socket.h>
#import <sys/types.h>
#import <sys/ioctl.h>
#import <sys/poll.h>
#import <sys/uio.h>
#import <unistd.h>

#if ! __has_feature(objc_arc)
#warning This file must be compiled with ARC. Use -fobjc-arc flag (or convert project to ARC).
// For more information see: https://github.com/robbiehanson/CocoaAsyncSocket/wiki/ARC
#endif

/**
 * Does ARC support support GCD objects?
 * It does if the minimum deployment target is iOS 6+ or Mac OS X 10.8+
**/
#if TARGET_OS_IPHONE

  // Compiling for iOS

  #if __IPHONE_OS_VERSION_MIN_REQUIRED >= 60000 // iOS 6.0 or later
    #define NEEDS_DISPATCH_RETAIN_RELEASE 0
  #else                                         // iOS 5.X or earlier
    #define NEEDS_DISPATCH_RETAIN_RELEASE 1
  #endif

#else

  // Compiling for Mac OS X

  #if MAC_OS_X_VERSION_MIN_REQUIRED >= 1080     // Mac OS X 10.8 or later
    #define NEEDS_DISPATCH_RETAIN_RELEASE 0
  #else
    #define NEEDS_DISPATCH_RETAIN_RELEASE 1     // Mac OS X 10.7 or earlier
  #endif

#endif


#if 0

// Logging Enabled - See log level below

// Logging uses the CocoaLumberjack framework (which is also GCD based).
// https://github.com/CocoaLumberjack/CocoaLumberjack
// 
// It allows us to do a lot of logging without significantly slowing down the code.
#import "DDLog.h"

#define LogAsync   YES
#define LogContext 65535

#define LogObjc(flg, frmt, ...) LOG_OBJC_MAYBE(LogAsync, logLevel, flg, LogContext, frmt, ##__VA_ARGS__)
#define LogC(flg, frmt, ...)    LOG_C_MAYBE(LogAsync, logLevel, flg, LogContext, frmt, ##__VA_ARGS__)

#define LogError(frmt, ...)     LogObjc(LOG_FLAG_ERROR,   (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogWarn(frmt, ...)      LogObjc(LOG_FLAG_WARN,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogInfo(frmt, ...)      LogObjc(LOG_FLAG_INFO,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogVerbose(frmt, ...)   LogObjc(LOG_FLAG_VERBOSE, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)

#define LogCError(frmt, ...)    LogC(LOG_FLAG_ERROR,   (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCWarn(frmt, ...)     LogC(LOG_FLAG_WARN,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCInfo(frmt, ...)     LogC(LOG_FLAG_INFO,    (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)
#define LogCVerbose(frmt, ...)  LogC(LOG_FLAG_VERBOSE, (@"%@: " frmt), THIS_FILE, ##__VA_ARGS__)

#define LogTrace()              LogObjc(LOG_FLAG_VERBOSE, @"%@: %@", THIS_FILE, THIS_METHOD)
#define LogCTrace()             LogC(LOG_FLAG_VERBOSE, @"%@: %s", THIS_FILE, __FUNCTION__)

// Log levels : off, error, warn, info, verbose
static const int logLevel = LOG_LEVEL_VERBOSE;

#else

// Logging Disabled

#define LogError(frmt, ...)     {}
#define LogWarn(frmt, ...)      {}
#define LogInfo(frmt, ...)      {}
#define LogVerbose(frmt, ...)   {}

#define LogCError(frmt, ...)    {}
#define LogCWarn(frmt, ...)     {}
#define LogCInfo(frmt, ...)     {}
#define LogCVerbose(frmt, ...)  {}

#define LogTrace()              {}
#define LogCTrace(frmt, ...)    {}

#endif

/**
 * Seeing a return statements within an inner block
 * can sometimes be mistaken for a return point of the enclosing method.
 * This makes inline blocks a bit easier to read.
**/
#define return_from_block  return

/**
 * A socket file descriptor is really just an integer.
 * It represents the index of the socket within the kernel.
 * This makes invalid file descriptor comparisons easier to read.
**/
#define SOCKET_NULL -1


NSString *const GCDAsyncSocketException = @"GCDAsyncSocketException";
NSString *const GCDAsyncSocketErrorDomain = @"GCDAsyncSocketErrorDomain";

NSString *const GCDAsyncSocketQueueName = @"GCDAsyncSocket";
NSString *const GCDAsyncSocketThreadName = @"GCDAsyncSocket-CFStream";

#if SECURE_TRANSPORT_MAYBE_AVAILABLE
NSString *const GCDAsyncSocketSSLCipherSuites = @"GCDAsyncSocketSSLCipherSuites";
#if TARGET_OS_IPHONE
NSString *const GCDAsyncSocketSSLProtocolVersionMin = @"GCDAsyncSocketSSLProtocolVersionMin";
NSString *const GCDAsyncSocketSSLProtocolVersionMax = @"GCDAsyncSocketSSLProtocolVersionMax";
#else
NSString *const GCDAsyncSocketSSLDiffieHellmanParameters = @"GCDAsyncSocketSSLDiffieHellmanParameters";
#endif
#endif

enum GCDAsyncSocketFlags
{
    kSocketStarted                 = 1 <<  0,  // If set, socket has been started (accepting/connecting)
    kConnected                     = 1 <<  1,  // If set, the socket is connected
    kForbidReadsWrites             = 1 <<  2,  // If set, no new reads or writes are allowed
    kReadsPaused                   = 1 <<  3,  // If set, reads are paused due to possible timeout
    kWritesPaused                  = 1 <<  4,  // If set, writes are paused due to possible timeout
    kDisconnectAfterReads          = 1 <<  5,  // If set, disconnect after no more reads are queued
    kDisconnectAfterWrites         = 1 <<  6,  // If set, disconnect after no more writes are queued
    kSocketCanAcceptBytes          = 1 <<  7,  // If set, we know socket can accept bytes. If unset, it's unknown.
    kReadSourceSuspended           = 1 <<  8,  // If set, the read source is suspended
    kWriteSourceSuspended          = 1 <<  9,  // If set, the write source is suspended
    kQueuedTLS                     = 1 << 10,  // If set, we've queued an upgrade to TLS
    kStartingReadTLS               = 1 << 11,  // If set, we're waiting for TLS negotiation to complete
    kStartingWriteTLS              = 1 << 12,  // If set, we're waiting for TLS negotiation to complete
    kSocketSecure                  = 1 << 13,  // If set, socket is using secure communication via SSL/TLS
    kSocketHasReadEOF              = 1 << 14,  // If set, we have read EOF from socket
    kReadStreamClosed              = 1 << 15,  // If set, we've read EOF plus prebuffer has been drained
#if TARGET_OS_IPHONE
    kAddedStreamsToRunLoop         = 1 << 16,  // If set, CFStreams have been added to listener thread
    kUsingCFStreamForTLS           = 1 << 17,  // If set, we're forced to use CFStream instead of SecureTransport
    kSecureSocketHasBytesAvailable = 1 << 18,  // If set, CFReadStream has notified us of bytes available
#endif
};

enum GCDAsyncSocketConfig
{
    kIPv4Disabled              = 1 << 0,  // If set, IPv4 is disabled
    kIPv6Disabled              = 1 << 1,  // If set, IPv6 is disabled
    kPreferIPv6                = 1 << 2,  // If set, IPv6 is preferred over IPv4
    kAllowHalfDuplexConnection = 1 << 3,  // If set, the socket will stay open even if the read stream closes
};

#if TARGET_OS_IPHONE
  static NSThread *cfstreamThread;  // Used for CFStreams
#endif

@interface GCDAsyncSocket ()
{
    uint32_t flags;
    uint16_t config;
    
#if __has_feature(objc_arc_weak)
    __weak id delegate;
#else
    __unsafe_unretained id delegate;
#endif
    dispatch_queue_t delegateQueue;
    
    int socket4FD;
    int socket6FD;
    int connectIndex;
    NSData * connectInterface4;
    NSData * connectInterface6;
    
    dispatch_queue_t socketQueue;
    
    dispatch_source_t accept4Source;
    dispatch_source_t accept6Source;
    dispatch_source_t connectTimer;
    dispatch_source_t readSource;
    dispatch_source_t writeSource;
    dispatch_source_t readTimer;
    dispatch_source_t writeTimer;
    
    NSMutableArray *readQueue;
    NSMutableArray *writeQueue;
    
    GCDAsyncReadPacket *currentRead;
    GCDAsyncWritePacket *currentWrite;
    
    unsigned long socketFDBytesAvailable;
    
    GCDAsyncSocketPreBuffer *preBuffer;
        
#if TARGET_OS_IPHONE
    CFStreamClientContext streamContext;
    CFReadStreamRef readStream;
    CFWriteStreamRef writeStream;
#endif
#if SECURE_TRANSPORT_MAYBE_AVAILABLE
    SSLContextRef sslContext;
    GCDAsyncSocketPreBuffer *sslPreBuffer;
    size_t sslWriteCachedLength;
    OSStatus sslErrCode;
#endif
    
    void *IsOnSocketQueueOrTargetQueueKey;
    
    id userData;
}
// Accepting
- (BOOL)doAccept:(int)socketFD;

// Connecting
- (void)startConnectTimeout:(NSTimeInterval)timeout;
- (void)endConnectTimeout;
- (void)doConnectTimeout;
- (void)lookup:(int)aConnectIndex host:(NSString *)host port:(uint16_t)port;
- (void)lookup:(int)aConnectIndex didSucceedWithAddress4:(NSData *)address4 address6:(NSData *)address6;
- (void)lookup:(int)aConnectIndex didFail:(NSError *)error;
- (BOOL)connectWithAddress4:(NSData *)address4 address6:(NSData *)address6 error:(NSError **)errPtr;
- (void)didConnect:(int)aConnectIndex;
- (void)didNotConnect:(int)aConnectIndex error:(NSError *)error;

// Disconnect
- (void)closeWithError:(NSError *)error;
- (void)maybeClose;

// Errors
- (NSError *)badConfigError:(NSString *)msg;
- (NSError *)badParamError:(NSString *)msg;
- (NSError *)gaiError:(int)gai_error;
- (NSError *)errnoError;
- (NSError *)errnoErrorWithReason:(NSString *)reason;
- (NSError *)connectTimeoutError;
- (NSError *)otherError:(NSString *)msg;

// Diagnostics
- (NSString *)connectedHost4;
- (NSString *)connectedHost6;
- (uint16_t)connectedPort4;
- (uint16_t)connectedPort6;
- (NSString *)localHost4;
- (NSString *)localHost6;
- (uint16_t)localPort4;
- (uint16_t)localPort6;
- (NSString *)connectedHostFromSocket4:(int)socketFD;
- (NSString *)connectedHostFromSocket6:(int)socketFD;
- (uint16_t)connectedPortFromSocket4:(int)socketFD;
- (uint16_t)connectedPortFromSocket6:(int)socketFD;
- (NSString *)localHostFromSocket4:(int)socketFD;
- (NSString *)localHostFromSocket6:(int)socketFD;
- (uint16_t)localPortFromSocket4:(int)socketFD;
- (uint16_t)localPortFromSocket6:(int)socketFD;

// Utilities
- (void)getInterfaceAddress4:(NSMutableData **)addr4Ptr
                    address6:(NSMutableData **)addr6Ptr
             fromDescription:(NSString *)interfaceDescription
                        port:(uint16_t)port;
- (void)setupReadAndWriteSourcesForNewlyConnectedSocket:(int)socketFD;
- (void)suspendReadSource;
- (void)resumeReadSource;
- (void)suspendWriteSource;
- (void)resumeWriteSource;

// Reading
- (void)maybeDequeueRead;
- (void)flushSSLBuffers;
- (void)doReadData;
- (void)doReadEOF;
- (void)completeCurrentRead;
- (void)endCurrentRead;
- (void)setupReadTimerWithTimeout:(NSTimeInterval)timeout;
- (void)doReadTimeout;
- (void)doReadTimeoutWithExtension:(NSTimeInterval)timeoutExtension;

// Writing
- (void)maybeDequeueWrite;
- (void)doWriteData;
- (void)completeCurrentWrite;
- (void)endCurrentWrite;
- (void)setupWriteTimerWithTimeout:(NSTimeInterval)timeout;
- (void)doWriteTimeout;
- (void)doWriteTimeoutWithExtension:(NSTimeInterval)timeoutExtension;

// Security
- (void)maybeStartTLS;
#if SECURE_TRANSPORT_MAYBE_AVAILABLE
- (void)ssl_startTLS;
- (void)ssl_continueSSLHandshake;
#endif
#if TARGET_OS_IPHONE
- (void)cf_startTLS;
#endif

// CFStream
#if TARGET_OS_IPHONE
+ (void)startCFStreamThreadIfNeeded;
- (BOOL)createReadAndWriteStream;
- (BOOL)registerForStreamCallbacksIncludingReadWrite:(BOOL)includeReadWrite;
- (BOOL)addStreamsToRunLoop;
- (BOOL)openStreams;
- (void)removeStreamsFromRunLoop;
#endif

// Class Methods
+ (NSString *)hostFromSockaddr4:(const struct sockaddr_in *)pSockaddr4;
+ (NSString *)hostFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6;
+ (uint16_t)portFromSockaddr4:(const struct sockaddr_in *)pSockaddr4;
+ (uint16_t)portFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6;

@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * A PreBuffer is used when there is more data available on the socket
 * than is being requested by current read request.
 * In this case we slurp up all data from the socket (to minimize sys calls),
 * and store additional yet unread data in a "prebuffer".
 * 
 * The prebuffer is entirely drained before we read from the socket again.
 * In other words, a large chunk of data is written is written to the prebuffer.
 * The prebuffer is then drained via a series of one or more reads (for subsequent read request(s)).
 * 
 * A ring buffer was once used for this purpose.
 * But a ring buffer takes up twice as much memory as needed (double the size for mirroring).
 * In fact, it generally takes up more than twice the needed size as everything has to be rounded up to vm_page_size.
 * And since the prebuffer is always completely drained after being written to, a full ring buffer isn't needed.
 * 
 * The current design is very simple and straight-forward, while also keeping memory requirements lower.
**/

@interface GCDAsyncSocketPreBuffer : NSObject
{
    uint8_t *preBuffer;
    size_t preBufferSize;
    
    uint8_t *readPointer;
    uint8_t *writePointer;
}

- (id)initWithCapacity:(size_t)numBytes;

- (void)ensureCapacityForWrite:(size_t)numBytes;

- (size_t)availableBytes;
- (uint8_t *)readBuffer;

- (void)getReadBuffer:(uint8_t **)bufferPtr availableBytes:(size_t *)availableBytesPtr;

- (size_t)availableSpace;
- (uint8_t *)writeBuffer;

- (void)getWriteBuffer:(uint8_t **)bufferPtr availableSpace:(size_t *)availableSpacePtr;

- (void)didRead:(size_t)bytesRead;
- (void)didWrite:(size_t)bytesWritten;

- (void)reset;

@end

@implementation GCDAsyncSocketPreBuffer

- (id)initWithCapacity:(size_t)numBytes
{
    if ((self = [super init]))
    {
        preBufferSize = numBytes;
        preBuffer = malloc(preBufferSize);
        
        readPointer = preBuffer;
        writePointer = preBuffer;
    }
    return self;
}

- (void)dealloc
{
    if (preBuffer)
        free(preBuffer);
}

- (void)ensureCapacityForWrite:(size_t)numBytes
{
    size_t availableSpace = preBufferSize - (writePointer - readPointer);
    
    if (numBytes > availableSpace)
    {
        size_t additionalBytes = numBytes - availableSpace;
        
        size_t newPreBufferSize = preBufferSize + additionalBytes;
        uint8_t *newPreBuffer = realloc(preBuffer, newPreBufferSize);
        
        size_t readPointerOffset = readPointer - preBuffer;
        size_t writePointerOffset = writePointer - preBuffer;
        
        preBuffer = newPreBuffer;
        preBufferSize = newPreBufferSize;
        
        readPointer = preBuffer + readPointerOffset;
        writePointer = preBuffer + writePointerOffset;
    }
}

- (size_t)availableBytes
{
    return writePointer - readPointer;
}

- (uint8_t *)readBuffer
{
    return readPointer;
}

- (void)getReadBuffer:(uint8_t **)bufferPtr availableBytes:(size_t *)availableBytesPtr
{
    if (bufferPtr) *bufferPtr = readPointer;
    if (availableBytesPtr) *availableBytesPtr = writePointer - readPointer;
}

- (void)didRead:(size_t)bytesRead
{
    readPointer += bytesRead;
    
    if (readPointer == writePointer)
    {
        // The prebuffer has been drained. Reset pointers.
        readPointer  = preBuffer;
        writePointer = preBuffer;
    }
}

- (size_t)availableSpace
{
    return preBufferSize - (writePointer - readPointer);
}

- (uint8_t *)writeBuffer
{
    return writePointer;
}

- (void)getWriteBuffer:(uint8_t **)bufferPtr availableSpace:(size_t *)availableSpacePtr
{
    if (bufferPtr) *bufferPtr = writePointer;
    if (availableSpacePtr) *availableSpacePtr = preBufferSize - (writePointer - readPointer);
}

- (void)didWrite:(size_t)bytesWritten
{
    writePointer += bytesWritten;
}

- (void)reset
{
    readPointer  = preBuffer;
    writePointer = preBuffer;
}

@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * The GCDAsyncReadPacket encompasses the instructions for any given read.
 * The content of a read packet allows the code to determine if we're:
 *  - reading to a certain length
 *  - reading to a certain separator
 *  - or simply reading the first chunk of available data
**/
@interface GCDAsyncReadPacket : NSObject
{
  @public
    NSMutableData *buffer;
    NSUInteger startOffset;
    NSUInteger bytesDone;
    NSUInteger maxLength;
    NSTimeInterval timeout;
    NSUInteger readLength;
    NSData *term;
    BOOL bufferOwner;
    NSUInteger originalBufferLength;
    long tag;
}
- (id)initWithData:(NSMutableData *)d
       startOffset:(NSUInteger)s
         maxLength:(NSUInteger)m
           timeout:(NSTimeInterval)t
        readLength:(NSUInteger)l
        terminator:(NSData *)e
               tag:(long)i;

- (void)ensureCapacityForAdditionalDataOfLength:(NSUInteger)bytesToRead;

- (NSUInteger)optimalReadLengthWithDefault:(NSUInteger)defaultValue shouldPreBuffer:(BOOL *)shouldPreBufferPtr;

- (NSUInteger)readLengthForNonTermWithHint:(NSUInteger)bytesAvailable;
- (NSUInteger)readLengthForTermWithHint:(NSUInteger)bytesAvailable shouldPreBuffer:(BOOL *)shouldPreBufferPtr;
- (NSUInteger)readLengthForTermWithPreBuffer:(GCDAsyncSocketPreBuffer *)preBuffer found:(BOOL *)foundPtr;

- (NSInteger)searchForTermAfterPreBuffering:(ssize_t)numBytes;

@end

@implementation GCDAsyncReadPacket

- (id)initWithData:(NSMutableData *)d
       startOffset:(NSUInteger)s
         maxLength:(NSUInteger)m
           timeout:(NSTimeInterval)t
        readLength:(NSUInteger)l
        terminator:(NSData *)e
               tag:(long)i
{
    if((self = [super init]))
    {
        bytesDone = 0;
        maxLength = m;
        timeout = t;
        readLength = l;
        term = [e copy];
        tag = i;
        
        if (d)
        {
            buffer = d;
            startOffset = s;
            bufferOwner = NO;
            originalBufferLength = [d length];
        }
        else
        {
            if (readLength > 0)
                buffer = [[NSMutableData alloc] initWithLength:readLength];
            else
                buffer = [[NSMutableData alloc] initWithLength:0];
            
            startOffset = 0;
            bufferOwner = YES;
            originalBufferLength = 0;
        }
    }
    return self;
}

/**
 * Increases the length of the buffer (if needed) to ensure a read of the given size will fit.
**/
- (void)ensureCapacityForAdditionalDataOfLength:(NSUInteger)bytesToRead
{
    NSUInteger buffSize = [buffer length];
    NSUInteger buffUsed = startOffset + bytesDone;
    
    NSUInteger buffSpace = buffSize - buffUsed;
    
    if (bytesToRead > buffSpace)
    {
        NSUInteger buffInc = bytesToRead - buffSpace;
        
        [buffer increaseLengthBy:buffInc];
    }
}

/**
 * This method is used when we do NOT know how much data is available to be read from the socket.
 * This method returns the default value unless it exceeds the specified readLength or maxLength.
 * 
 * Furthermore, the shouldPreBuffer decision is based upon the packet type,
 * and whether the returned value would fit in the current buffer without requiring a resize of the buffer.
**/
- (NSUInteger)optimalReadLengthWithDefault:(NSUInteger)defaultValue shouldPreBuffer:(BOOL *)shouldPreBufferPtr
{
    NSUInteger result;
    
    if (readLength > 0)
    {
        // Read a specific length of data
        
        result = MIN(defaultValue, (readLength - bytesDone));
        
        // There is no need to prebuffer since we know exactly how much data we need to read.
        // Even if the buffer isn't currently big enough to fit this amount of data,
        // it would have to be resized eventually anyway.
        
        if (shouldPreBufferPtr)
            *shouldPreBufferPtr = NO;
    }
    else
    {
        // Either reading until we find a specified terminator,
        // or we're simply reading all available data.
        // 
        // In other words, one of:
        // 
        // - readDataToData packet
        // - readDataWithTimeout packet
        
        if (maxLength > 0)
            result =  MIN(defaultValue, (maxLength - bytesDone));
        else
            result = defaultValue;
        
        // Since we don't know the size of the read in advance,
        // the shouldPreBuffer decision is based upon whether the returned value would fit
        // in the current buffer without requiring a resize of the buffer.
        // 
        // This is because, in all likelyhood, the amount read from the socket will be less than the default value.
        // Thus we should avoid over-allocating the read buffer when we can simply use the pre-buffer instead.
        
        if (shouldPreBufferPtr)
        {
            NSUInteger buffSize = [buffer length];
            NSUInteger buffUsed = startOffset + bytesDone;
            
            NSUInteger buffSpace = buffSize - buffUsed;
            
            if (buffSpace >= result)
                *shouldPreBufferPtr = NO;
            else
                *shouldPreBufferPtr = YES;
        }
    }
    
    return result;
}

/**
 * For read packets without a set terminator, returns the amount of data
 * that can be read without exceeding the readLength or maxLength.
 * 
 * The given parameter indicates the number of bytes estimated to be available on the socket,
 * which is taken into consideration during the calculation.
 * 
 * The given hint MUST be greater than zero.
**/
- (NSUInteger)readLengthForNonTermWithHint:(NSUInteger)bytesAvailable
{
    NSAssert(term == nil, @"This method does not apply to term reads");
    NSAssert(bytesAvailable > 0, @"Invalid parameter: bytesAvailable");
    
    if (readLength > 0)
    {
        // Read a specific length of data
        
        return MIN(bytesAvailable, (readLength - bytesDone));
        
        // No need to avoid resizing the buffer.
        // If the user provided their own buffer,
        // and told us to read a certain length of data that exceeds the size of the buffer,
        // then it is clear that our code will resize the buffer during the read operation.
        // 
        // This method does not actually do any resizing.
        // The resizing will happen elsewhere if needed.
    }
    else
    {
        // Read all available data
        
        NSUInteger result = bytesAvailable;
        
        if (maxLength > 0)
        {
            result = MIN(result, (maxLength - bytesDone));
        }
        
        // No need to avoid resizing the buffer.
        // If the user provided their own buffer,
        // and told us to read all available data without giving us a maxLength,
        // then it is clear that our code might resize the buffer during the read operation.
        // 
        // This method does not actually do any resizing.
        // The resizing will happen elsewhere if needed.
        
        return result;
    }
}

/**
 * For read packets with a set terminator, returns the amount of data
 * that can be read without exceeding the maxLength.
 * 
 * The given parameter indicates the number of bytes estimated to be available on the socket,
 * which is taken into consideration during the calculation.
 * 
 * To optimize memory allocations, mem copies, and mem moves
 * the shouldPreBuffer boolean value will indicate if the data should be read into a prebuffer first,
 * or if the data can be read directly into the read packet's buffer.
**/
- (NSUInteger)readLengthForTermWithHint:(NSUInteger)bytesAvailable shouldPreBuffer:(BOOL *)shouldPreBufferPtr
{
    NSAssert(term != nil, @"This method does not apply to non-term reads");
    NSAssert(bytesAvailable > 0, @"Invalid parameter: bytesAvailable");
    
    
    NSUInteger result = bytesAvailable;
    
    if (maxLength > 0)
    {
        result = MIN(result, (maxLength - bytesDone));
    }
    
    // Should the data be read into the read packet's buffer, or into a pre-buffer first?
    // 
    // One would imagine the preferred option is the faster one.
    // So which one is faster?
    // 
    // Reading directly into the packet's buffer requires:
    // 1. Possibly resizing packet buffer (malloc/realloc)
    // 2. Filling buffer (read)
    // 3. Searching for term (memcmp)
    // 4. Possibly copying overflow into prebuffer (malloc/realloc, memcpy)
    // 
    // Reading into prebuffer first:
    // 1. Possibly resizing prebuffer (malloc/realloc)
    // 2. Filling buffer (read)
    // 3. Searching for term (memcmp)
    // 4. Copying underflow into packet buffer (malloc/realloc, memcpy)
    // 5. Removing underflow from prebuffer (memmove)
    // 
    // Comparing the performance of the two we can see that reading
    // data into the prebuffer first is slower due to the extra memove.
    // 
    // However:
    // The implementation of NSMutableData is open source via core foundation's CFMutableData.
    // Decreasing the length of a mutable data object doesn't cause a realloc.
    // In other words, the capacity of a mutable data object can grow, but doesn't shrink.
    // 
    // This means the prebuffer will rarely need a realloc.
    // The packet buffer, on the other hand, may often need a realloc.
    // This is especially true if we are the buffer owner.
    // Furthermore, if we are constantly realloc'ing the packet buffer,
    // and then moving the overflow into the prebuffer,
    // then we're consistently over-allocating memory for each term read.
    // And now we get into a bit of a tradeoff between speed and memory utilization.
    // 
    // The end result is that the two perform very similarly.
    // And we can answer the original question very simply by another means.
    // 
    // If we can read all the data directly into the packet's buffer without resizing it first,
    // then we do so. Otherwise we use the prebuffer.
    
    if (shouldPreBufferPtr)
    {
        NSUInteger buffSize = [buffer length];
        NSUInteger buffUsed = startOffset + bytesDone;
        
        if ((buffSize - buffUsed) >= result)
            *shouldPreBufferPtr = NO;
        else
            *shouldPreBufferPtr = YES;
    }
    
    return result;
}

/**
 * For read packets with a set terminator,
 * returns the amount of data that can be read from the given preBuffer,
 * without going over a terminator or the maxLength.
 * 
 * It is assumed the terminator has not already been read.
**/
- (NSUInteger)readLengthForTermWithPreBuffer:(GCDAsyncSocketPreBuffer *)preBuffer found:(BOOL *)foundPtr
{
    NSAssert(term != nil, @"This method does not apply to non-term reads");
    NSAssert([preBuffer availableBytes] > 0, @"Invoked with empty pre buffer!");
    
    // We know that the terminator, as a whole, doesn't exist in our own buffer.
    // But it is possible that a _portion_ of it exists in our buffer.
    // So we're going to look for the terminator starting with a portion of our own buffer.
    // 
    // Example:
    // 
    // term length      = 3 bytes
    // bytesDone        = 5 bytes
    // preBuffer length = 5 bytes
    // 
    // If we append the preBuffer to our buffer,
    // it would look like this:
    // 
    // ---------------------
    // |B|B|B|B|B|P|P|P|P|P|
    // ---------------------
    // 
    // So we start our search here:
    // 
    // ---------------------
    // |B|B|B|B|B|P|P|P|P|P|
    // -------^-^-^---------
    // 
    // And move forwards...
    // 
    // ---------------------
    // |B|B|B|B|B|P|P|P|P|P|
    // ---------^-^-^-------
    // 
    // Until we find the terminator or reach the end.
    // 
    // ---------------------
    // |B|B|B|B|B|P|P|P|P|P|
    // ---------------^-^-^-
    
    BOOL found = NO;
    
    NSUInteger termLength = [term length];
    NSUInteger preBufferLength = [preBuffer availableBytes];
    
    if ((bytesDone + preBufferLength) < termLength)
    {
        // Not enough data for a full term sequence yet
        return preBufferLength;
    }
    
    NSUInteger maxPreBufferLength;
    if (maxLength > 0) {
        maxPreBufferLength = MIN(preBufferLength, (maxLength - bytesDone));
        
        // Note: maxLength >= termLength
    }
    else {
        maxPreBufferLength = preBufferLength;
    }
    
    uint8_t seq[termLength];
    const void *termBuf = [term bytes];
    
    NSUInteger bufLen = MIN(bytesDone, (termLength - 1));
    uint8_t *buf = (uint8_t *)[buffer mutableBytes] + startOffset + bytesDone - bufLen;
    
    NSUInteger preLen = termLength - bufLen;
    const uint8_t *pre = [preBuffer readBuffer];
    
    NSUInteger loopCount = bufLen + maxPreBufferLength - termLength + 1; // Plus one. See example above.
    
    NSUInteger result = maxPreBufferLength;
    
    NSUInteger i;
    for (i = 0; i < loopCount; i++)
    {
        if (bufLen > 0)
        {
            // Combining bytes from buffer and preBuffer
            
            memcpy(seq, buf, bufLen);
            memcpy(seq + bufLen, pre, preLen);
            
            if (memcmp(seq, termBuf, termLength) == 0)
            {
                result = preLen;
                found = YES;
                break;
            }
            
            buf++;
            bufLen--;
            preLen++;
        }
        else
        {
            // Comparing directly from preBuffer
            
            if (memcmp(pre, termBuf, termLength) == 0)
            {
                NSUInteger preOffset = pre - [preBuffer readBuffer]; // pointer arithmetic
                
                result = preOffset + termLength;
                found = YES;
                break;
            }
            
            pre++;
        }
    }
    
    // There is no need to avoid resizing the buffer in this particular situation.
    
    if (foundPtr) *foundPtr = found;
    return result;
}

/**
 * For read packets with a set terminator, scans the packet buffer for the term.
 * It is assumed the terminator had not been fully read prior to the new bytes.
 * 
 * If the term is found, the number of excess bytes after the term are returned.
 * If the term is not found, this method will return -1.
 * 
 * Note: A return value of zero means the term was found at the very end.
 * 
 * Prerequisites:
 * The given number of bytes have been added to the end of our buffer.
 * Our bytesDone variable has NOT been changed due to the prebuffered bytes.
**/
- (NSInteger)searchForTermAfterPreBuffering:(ssize_t)numBytes
{
    NSAssert(term != nil, @"This method does not apply to non-term reads");
    
    // The implementation of this method is very similar to the above method.
    // See the above method for a discussion of the algorithm used here.
    
    uint8_t *buff = [buffer mutableBytes];
    NSUInteger buffLength = bytesDone + numBytes;
    
    const void *termBuff = [term bytes];
    NSUInteger termLength = [term length];
    
    // Note: We are dealing with unsigned integers,
    // so make sure the math doesn't go below zero.
    
    NSUInteger i = ((buffLength - numBytes) >= termLength) ? (buffLength - numBytes - termLength + 1) : 0;
    
    while (i + termLength <= buffLength)
    {
        uint8_t *subBuffer = buff + startOffset + i;
        
        if (memcmp(subBuffer, termBuff, termLength) == 0)
        {
            return buffLength - (i + termLength);
        }
        
        i++;
    }
    
    return -1;
}


@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * The GCDAsyncWritePacket encompasses the instructions for any given write.
**/
@interface GCDAsyncWritePacket : NSObject
{
  @public
    NSData *buffer;
    NSUInteger bytesDone;
    long tag;
    NSTimeInterval timeout;
}
- (id)initWithData:(NSData *)d timeout:(NSTimeInterval)t tag:(long)i;
@end

@implementation GCDAsyncWritePacket

- (id)initWithData:(NSData *)d timeout:(NSTimeInterval)t tag:(long)i
{
    if((self = [super init]))
    {
        buffer = d; // Retain not copy. For performance as documented in header file.
        bytesDone = 0;
        timeout = t;
        tag = i;
    }
    return self;
}


@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * The GCDAsyncSpecialPacket encompasses special instructions for interruptions in the read/write queues.
 * This class my be altered to support more than just TLS in the future.
**/
@interface GCDAsyncSpecialPacket : NSObject
{
  @public
    NSDictionary *tlsSettings;
}
- (id)initWithTLSSettings:(NSDictionary *)settings;
@end

@implementation GCDAsyncSpecialPacket

- (id)initWithTLSSettings:(NSDictionary *)settings
{
    if((self = [super init]))
    {
        tlsSettings = [settings copy];
    }
    return self;
}


@end

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark -
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

@implementation GCDAsyncSocket

- (id)init
{
    return [self initWithDelegate:nil delegateQueue:NULL socketQueue:NULL];
}

- (id)initWithSocketQueue:(dispatch_queue_t)sq
{
    return [self initWithDelegate:nil delegateQueue:NULL socketQueue:sq];
}

- (id)initWithDelegate:(id)aDelegate delegateQueue:(dispatch_queue_t)dq
{
    return [self initWithDelegate:aDelegate delegateQueue:dq socketQueue:NULL];
}

- (id)initWithDelegate:(id)aDelegate delegateQueue:(dispatch_queue_t)dq socketQueue:(dispatch_queue_t)sq
{
    if((self = [super init]))
    {
        delegate = aDelegate;
        delegateQueue = dq;
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        if (dq) dispatch_retain(dq);
        #endif
        
        socket4FD = SOCKET_NULL;
        socket6FD = SOCKET_NULL;
        connectIndex = 0;
        
        if (sq)
        {
            NSAssert(sq != dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_LOW, 0),
                     @"The given socketQueue parameter must not be a concurrent queue.");
            NSAssert(sq != dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0),
                     @"The given socketQueue parameter must not be a concurrent queue.");
            NSAssert(sq != dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0),
                     @"The given socketQueue parameter must not be a concurrent queue.");
            
            socketQueue = sq;
            #if NEEDS_DISPATCH_RETAIN_RELEASE
            dispatch_retain(sq);
            #endif
        }
        else
        {
            socketQueue = dispatch_queue_create([GCDAsyncSocketQueueName UTF8String], NULL);
        }
        
        // The dispatch_queue_set_specific() and dispatch_get_specific() functions take a "void *key" parameter.
        // From the documentation:
        //
        // > Keys are only compared as pointers and are never dereferenced.
        // > Thus, you can use a pointer to a static variable for a specific subsystem or
        // > any other value that allows you to identify the value uniquely.
        //
        // We're just going to use the memory address of an ivar.
        // Specifically an ivar that is explicitly named for our purpose to make the code more readable.
        //
        // However, it feels tedious (and less readable) to include the "&" all the time:
        // dispatch_get_specific(&IsOnSocketQueueOrTargetQueueKey)
        //
        // So we're going to make it so it doesn't matter if we use the '&' or not,
        // by assigning the value of the ivar to the address of the ivar.
        // Thus: IsOnSocketQueueOrTargetQueueKey == &IsOnSocketQueueOrTargetQueueKey;
        
        IsOnSocketQueueOrTargetQueueKey = &IsOnSocketQueueOrTargetQueueKey;
        
        void *nonNullUnusedPointer = (__bridge void *)self;
        dispatch_queue_set_specific(socketQueue, IsOnSocketQueueOrTargetQueueKey, nonNullUnusedPointer, NULL);
        
        readQueue = [[NSMutableArray alloc] initWithCapacity:5];
        currentRead = nil;
        
        writeQueue = [[NSMutableArray alloc] initWithCapacity:5];
        currentWrite = nil;
        
        preBuffer = [[GCDAsyncSocketPreBuffer alloc] initWithCapacity:(1024 * 4)];
    }
    return self;
}

- (void)dealloc
{
    LogInfo(@"%@ - %@ (start)", THIS_METHOD, self);
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        [self closeWithError:nil];
    }
    else
    {
        dispatch_sync(socketQueue, ^{
            [self closeWithError:nil];
        });
    }
    
    delegate = nil;
    
    #if NEEDS_DISPATCH_RETAIN_RELEASE
    if (delegateQueue) dispatch_release(delegateQueue);
    #endif
    delegateQueue = NULL;
    
    #if NEEDS_DISPATCH_RETAIN_RELEASE
    if (socketQueue) dispatch_release(socketQueue);
    #endif
    socketQueue = NULL;
    
    LogInfo(@"%@ - %@ (finish)", THIS_METHOD, self);
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Configuration
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (id)delegate
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return delegate;
    }
    else
    {
        __block id result;
        
        dispatch_sync(socketQueue, ^{
            result = delegate;
        });
        
        return result;
    }
}

- (void)setDelegate:(id)newDelegate synchronously:(BOOL)synchronously
{
    dispatch_block_t block = ^{
        delegate = newDelegate;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey)) {
        block();
    }
    else {
        if (synchronously)
            dispatch_sync(socketQueue, block);
        else
            dispatch_async(socketQueue, block);
    }
}

- (void)setDelegate:(id)newDelegate
{
    [self setDelegate:newDelegate synchronously:NO];
}

- (void)synchronouslySetDelegate:(id)newDelegate
{
    [self setDelegate:newDelegate synchronously:YES];
}

- (dispatch_queue_t)delegateQueue
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return delegateQueue;
    }
    else
    {
        __block dispatch_queue_t result;
        
        dispatch_sync(socketQueue, ^{
            result = delegateQueue;
        });
        
        return result;
    }
}

- (void)setDelegateQueue:(dispatch_queue_t)newDelegateQueue synchronously:(BOOL)synchronously
{
    dispatch_block_t block = ^{
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        if (delegateQueue) dispatch_release(delegateQueue);
        if (newDelegateQueue) dispatch_retain(newDelegateQueue);
        #endif
        
        delegateQueue = newDelegateQueue;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey)) {
        block();
    }
    else {
        if (synchronously)
            dispatch_sync(socketQueue, block);
        else
            dispatch_async(socketQueue, block);
    }
}

- (void)setDelegateQueue:(dispatch_queue_t)newDelegateQueue
{
    [self setDelegateQueue:newDelegateQueue synchronously:NO];
}

- (void)synchronouslySetDelegateQueue:(dispatch_queue_t)newDelegateQueue
{
    [self setDelegateQueue:newDelegateQueue synchronously:YES];
}

- (void)getDelegate:(id *)delegatePtr delegateQueue:(dispatch_queue_t *)delegateQueuePtr
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        if (delegatePtr) *delegatePtr = delegate;
        if (delegateQueuePtr) *delegateQueuePtr = delegateQueue;
    }
    else
    {
        __block id dPtr = NULL;
        __block dispatch_queue_t dqPtr = NULL;
        
        dispatch_sync(socketQueue, ^{
            dPtr = delegate;
            dqPtr = delegateQueue;
        });
        
        if (delegatePtr) *delegatePtr = dPtr;
        if (delegateQueuePtr) *delegateQueuePtr = dqPtr;
    }
}

- (void)setDelegate:(id)newDelegate delegateQueue:(dispatch_queue_t)newDelegateQueue synchronously:(BOOL)synchronously
{
    dispatch_block_t block = ^{
        
        delegate = newDelegate;
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        if (delegateQueue) dispatch_release(delegateQueue);
        if (newDelegateQueue) dispatch_retain(newDelegateQueue);
        #endif
        
        delegateQueue = newDelegateQueue;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey)) {
        block();
    }
    else {
        if (synchronously)
            dispatch_sync(socketQueue, block);
        else
            dispatch_async(socketQueue, block);
    }
}

- (void)setDelegate:(id)newDelegate delegateQueue:(dispatch_queue_t)newDelegateQueue
{
    [self setDelegate:newDelegate delegateQueue:newDelegateQueue synchronously:NO];
}

- (void)synchronouslySetDelegate:(id)newDelegate delegateQueue:(dispatch_queue_t)newDelegateQueue
{
    [self setDelegate:newDelegate delegateQueue:newDelegateQueue synchronously:YES];
}

- (BOOL)isIPv4Enabled
{
    // Note: YES means kIPv4Disabled is OFF
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return ((config & kIPv4Disabled) == 0);
    }
    else
    {
        __block BOOL result;
        
        dispatch_sync(socketQueue, ^{
            result = ((config & kIPv4Disabled) == 0);
        });
        
        return result;
    }
}

- (void)setIPv4Enabled:(BOOL)flag
{
    // Note: YES means kIPv4Disabled is OFF
    
    dispatch_block_t block = ^{
        
        if (flag)
            config &= ~kIPv4Disabled;
        else
            config |= kIPv4Disabled;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_async(socketQueue, block);
}

- (BOOL)isIPv6Enabled
{
    // Note: YES means kIPv6Disabled is OFF
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return ((config & kIPv6Disabled) == 0);
    }
    else
    {
        __block BOOL result;
        
        dispatch_sync(socketQueue, ^{
            result = ((config & kIPv6Disabled) == 0);
        });
        
        return result;
    }
}

- (void)setIPv6Enabled:(BOOL)flag
{
    // Note: YES means kIPv6Disabled is OFF
    
    dispatch_block_t block = ^{
        
        if (flag)
            config &= ~kIPv6Disabled;
        else
            config |= kIPv6Disabled;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_async(socketQueue, block);
}

- (BOOL)isIPv4PreferredOverIPv6
{
    // Note: YES means kPreferIPv6 is OFF
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return ((config & kPreferIPv6) == 0);
    }
    else
    {
        __block BOOL result;
        
        dispatch_sync(socketQueue, ^{
            result = ((config & kPreferIPv6) == 0);
        });
        
        return result;
    }
}

- (void)setPreferIPv4OverIPv6:(BOOL)flag
{
    // Note: YES means kPreferIPv6 is OFF
    
    dispatch_block_t block = ^{
        
        if (flag)
            config &= ~kPreferIPv6;
        else
            config |= kPreferIPv6;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_async(socketQueue, block);
}

- (id)userData
{
    __block id result = nil;
    
    dispatch_block_t block = ^{
        
        result = userData;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

- (void)setUserData:(id)arbitraryUserData
{
    dispatch_block_t block = ^{
        
        if (userData != arbitraryUserData)
        {
            userData = arbitraryUserData;
        }
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_async(socketQueue, block);
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Accepting
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (BOOL)acceptOnPort:(uint16_t)port error:(NSError **)errPtr
{
    return [self acceptOnInterface:nil port:port error:errPtr];
}

- (BOOL)acceptOnInterface:(NSString *)inInterface port:(uint16_t)port error:(NSError **)errPtr
{
    LogTrace();
    
    // Just in-case interface parameter is immutable.
    NSString *interface = [inInterface copy];
    
    __block BOOL result = NO;
    __block NSError *err = nil;
    
    // CreateSocket Block
    // This block will be invoked within the dispatch block below.
    
    int(^createSocket)(int, NSData*) = ^int (int domain, NSData *interfaceAddr) {
        
        int socketFD = socket(domain, SOCK_STREAM, 0);
        
        if (socketFD == SOCKET_NULL)
        {
            NSString *reason = @"Error in socket() function";
            err = [self errnoErrorWithReason:reason];
            
            return SOCKET_NULL;
        }
        
        int status;
        
        // Set socket options
        
        status = fcntl(socketFD, F_SETFL, O_NONBLOCK);
        if (status == -1)
        {
            NSString *reason = @"Error enabling non-blocking IO on socket (fcntl)";
            err = [self errnoErrorWithReason:reason];
            
            LogVerbose(@"close(socketFD)");
            close(socketFD);
            return SOCKET_NULL;
        }
        
        int reuseOn = 1;
        status = setsockopt(socketFD, SOL_SOCKET, SO_REUSEADDR, &reuseOn, sizeof(reuseOn));
        if (status == -1)
        {
            NSString *reason = @"Error enabling address reuse (setsockopt)";
            err = [self errnoErrorWithReason:reason];
            
            LogVerbose(@"close(socketFD)");
            close(socketFD);
            return SOCKET_NULL;
        }
        
        // Bind socket
        
        status = bind(socketFD, (const struct sockaddr *)[interfaceAddr bytes], (socklen_t)[interfaceAddr length]);
        if (status == -1)
        {
            NSString *reason = @"Error in bind() function";
            err = [self errnoErrorWithReason:reason];
            
            LogVerbose(@"close(socketFD)");
            close(socketFD);
            return SOCKET_NULL;
        }
        
        // Listen
        
        status = listen(socketFD, 1024);
        if (status == -1)
        {
            NSString *reason = @"Error in listen() function";
            err = [self errnoErrorWithReason:reason];
            
            LogVerbose(@"close(socketFD)");
            close(socketFD);
            return SOCKET_NULL;
        }
        
        return socketFD;
    };
    
    // Create dispatch block and run on socketQueue
    
    dispatch_block_t block = ^{ @autoreleasepool {
        
        if (delegate == nil) // Must have delegate set
        {
            NSString *msg = @"Attempting to accept without a delegate. Set a delegate first.";
            err = [self badConfigError:msg];
            
            return_from_block;
        }
        
        if (delegateQueue == NULL) // Must have delegate queue set
        {
            NSString *msg = @"Attempting to accept without a delegate queue. Set a delegate queue first.";
            err = [self badConfigError:msg];
            
            return_from_block;
        }
        
        BOOL isIPv4Disabled = (config & kIPv4Disabled) ? YES : NO;
        BOOL isIPv6Disabled = (config & kIPv6Disabled) ? YES : NO;
        
        if (isIPv4Disabled && isIPv6Disabled) // Must have IPv4 or IPv6 enabled
        {
            NSString *msg = @"Both IPv4 and IPv6 have been disabled. Must enable at least one protocol first.";
            err = [self badConfigError:msg];
            
            return_from_block;
        }
        
        if (![self isDisconnected]) // Must be disconnected
        {
            NSString *msg = @"Attempting to accept while connected or accepting connections. Disconnect first.";
            err = [self badConfigError:msg];
            
            return_from_block;
        }
        
        // Clear queues (spurious read/write requests post disconnect)
        [readQueue removeAllObjects];
        [writeQueue removeAllObjects];
        
        // Resolve interface from description
        
        NSMutableData *interface4 = nil;
        NSMutableData *interface6 = nil;
        
        [self getInterfaceAddress4:&interface4 address6:&interface6 fromDescription:interface port:port];
        
        if ((interface4 == nil) && (interface6 == nil))
        {
            NSString *msg = @"Unknown interface. Specify valid interface by name (e.g. \"en1\") or IP address.";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        if (isIPv4Disabled && (interface6 == nil))
        {
            NSString *msg = @"IPv4 has been disabled and specified interface doesn't support IPv6.";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        if (isIPv6Disabled && (interface4 == nil))
        {
            NSString *msg = @"IPv6 has been disabled and specified interface doesn't support IPv4.";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        BOOL enableIPv4 = !isIPv4Disabled && (interface4 != nil);
        BOOL enableIPv6 = !isIPv6Disabled && (interface6 != nil);
        
        // Create sockets, configure, bind, and listen
        
        if (enableIPv4)
        {
            LogVerbose(@"Creating IPv4 socket");
            socket4FD = createSocket(AF_INET, interface4);
            
            if (socket4FD == SOCKET_NULL)
            {
                return_from_block;
            }
        }
        
        if (enableIPv6)
        {
            LogVerbose(@"Creating IPv6 socket");
            
            if (enableIPv4 && (port == 0))
            {
                // No specific port was specified, so we allowed the OS to pick an available port for us.
                // Now we need to make sure the IPv6 socket listens on the same port as the IPv4 socket.
                
                struct sockaddr_in6 *addr6 = (struct sockaddr_in6 *)[interface6 mutableBytes];
                addr6->sin6_port = htons([self localPort4]);
            }
            
            socket6FD = createSocket(AF_INET6, interface6);
            
            if (socket6FD == SOCKET_NULL)
            {
                if (socket4FD != SOCKET_NULL)
                {
                    LogVerbose(@"close(socket4FD)");
                    close(socket4FD);
                }
                
                return_from_block;
            }
        }
        
        // Create accept sources
        
        if (enableIPv4)
        {
            accept4Source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, socket4FD, 0, socketQueue);
            
            int socketFD = socket4FD;
            dispatch_source_t acceptSource = accept4Source;
            
            dispatch_source_set_event_handler(accept4Source, ^{ @autoreleasepool {
                
                LogVerbose(@"event4Block");
                
                unsigned long i = 0;
                unsigned long numPendingConnections = dispatch_source_get_data(acceptSource);
                
                LogVerbose(@"numPendingConnections: %lu", numPendingConnections);
                
                while ([self doAccept:socketFD] && (++i < numPendingConnections));
            }});
            
            dispatch_source_set_cancel_handler(accept4Source, ^{
                
                #if NEEDS_DISPATCH_RETAIN_RELEASE
                LogVerbose(@"dispatch_release(accept4Source)");
                dispatch_release(acceptSource);
                #endif
                
                LogVerbose(@"close(socket4FD)");
                close(socketFD);
            });
            
            LogVerbose(@"dispatch_resume(accept4Source)");
            dispatch_resume(accept4Source);
        }
        
        if (enableIPv6)
        {
            accept6Source = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, socket6FD, 0, socketQueue);
            
            int socketFD = socket6FD;
            dispatch_source_t acceptSource = accept6Source;
            
            dispatch_source_set_event_handler(accept6Source, ^{ @autoreleasepool {
                
                LogVerbose(@"event6Block");
                
                unsigned long i = 0;
                unsigned long numPendingConnections = dispatch_source_get_data(acceptSource);
                
                LogVerbose(@"numPendingConnections: %lu", numPendingConnections);
                
                while ([self doAccept:socketFD] && (++i < numPendingConnections));
            }});
            
            dispatch_source_set_cancel_handler(accept6Source, ^{
                
                #if NEEDS_DISPATCH_RETAIN_RELEASE
                LogVerbose(@"dispatch_release(accept6Source)");
                dispatch_release(acceptSource);
                #endif
                
                LogVerbose(@"close(socket6FD)");
                close(socketFD);
            });
            
            LogVerbose(@"dispatch_resume(accept6Source)");
            dispatch_resume(accept6Source);
        }
        
        flags |= kSocketStarted;
        
        result = YES;
    }};
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    if (result == NO)
    {
        LogInfo(@"Error in accept: %@", err);
        
        if (errPtr)
            *errPtr = err;
    }
    
    return result;
}

- (BOOL)doAccept:(int)parentSocketFD
{
    LogTrace();
    
    BOOL isIPv4;
    int childSocketFD;
    NSData *childSocketAddress;
    
    if (parentSocketFD == socket4FD)
    {
        isIPv4 = YES;
        
        struct sockaddr_in addr;
        socklen_t addrLen = sizeof(addr);
        
        childSocketFD = accept(parentSocketFD, (struct sockaddr *)&addr, &addrLen);
        
        if (childSocketFD == -1)
        {
            LogWarn(@"Accept failed with error: %@", [self errnoError]);
            return NO;
        }
        
        childSocketAddress = [NSData dataWithBytes:&addr length:addrLen];
    }
    else // if (parentSocketFD == socket6FD)
    {
        isIPv4 = NO;
        
        struct sockaddr_in6 addr;
        socklen_t addrLen = sizeof(addr);
        
        childSocketFD = accept(parentSocketFD, (struct sockaddr *)&addr, &addrLen);
        
        if (childSocketFD == -1)
        {
            LogWarn(@"Accept failed with error: %@", [self errnoError]);
            return NO;
        }
        
        childSocketAddress = [NSData dataWithBytes:&addr length:addrLen];
    }
    
    // Enable non-blocking IO on the socket
    
    int result = fcntl(childSocketFD, F_SETFL, O_NONBLOCK);
    if (result == -1)
    {
        LogWarn(@"Error enabling non-blocking IO on accepted socket (fcntl)");
        return NO;
    }
    
    // Prevent SIGPIPE signals
    
    int nosigpipe = 1;
    setsockopt(childSocketFD, SOL_SOCKET, SO_NOSIGPIPE, &nosigpipe, sizeof(nosigpipe));
    
    // Notify delegate
    
    if (delegateQueue)
    {
        __strong id theDelegate = delegate;
        
        dispatch_async(delegateQueue, ^{ @autoreleasepool {
            
            // Query delegate for custom socket queue
            
            dispatch_queue_t childSocketQueue = NULL;
            
            if ([theDelegate respondsToSelector:@selector(newSocketQueueForConnectionFromAddress:onSocket:)])
            {
                childSocketQueue = [theDelegate newSocketQueueForConnectionFromAddress:childSocketAddress
                                                                              onSocket:self];
            }
            
            // Create GCDAsyncSocket instance for accepted socket
            
            GCDAsyncSocket *acceptedSocket = [[GCDAsyncSocket alloc] initWithDelegate:theDelegate
                                                                        delegateQueue:delegateQueue
                                                                          socketQueue:childSocketQueue];
            
            if (isIPv4)
                acceptedSocket->socket4FD = childSocketFD;
            else
                acceptedSocket->socket6FD = childSocketFD;
            
            acceptedSocket->flags = (kSocketStarted | kConnected);
            
            // Setup read and write sources for accepted socket
            
            dispatch_async(acceptedSocket->socketQueue, ^{ @autoreleasepool {
                
                [acceptedSocket setupReadAndWriteSourcesForNewlyConnectedSocket:childSocketFD];
            }});
            
            // Notify delegate
            
            if ([theDelegate respondsToSelector:@selector(socket:didAcceptNewSocket:)])
            {
                [theDelegate socket:self didAcceptNewSocket:acceptedSocket];
            }
            
            // Release the socket queue returned from the delegate (it was retained by acceptedSocket)
            #if NEEDS_DISPATCH_RETAIN_RELEASE
            if (childSocketQueue) dispatch_release(childSocketQueue);
            #endif
            
            // The accepted socket should have been retained by the delegate.
            // Otherwise it gets properly released when exiting the block.
        }});
    }
    
    return YES;
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Connecting
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * This method runs through the various checks required prior to a connection attempt.
 * It is shared between the connectToHost and connectToAddress methods.
 * 
**/
- (BOOL)preConnectWithInterface:(NSString *)interface error:(NSError **)errPtr
{
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    if (delegate == nil) // Must have delegate set
    {
        if (errPtr)
        {
            NSString *msg = @"Attempting to connect without a delegate. Set a delegate first.";
            *errPtr = [self badConfigError:msg];
        }
        return NO;
    }
    
    if (delegateQueue == NULL) // Must have delegate queue set
    {
        if (errPtr)
        {
            NSString *msg = @"Attempting to connect without a delegate queue. Set a delegate queue first.";
            *errPtr = [self badConfigError:msg];
        }
        return NO;
    }
    
    if (![self isDisconnected]) // Must be disconnected
    {
        if (errPtr)
        {
            NSString *msg = @"Attempting to connect while connected or accepting connections. Disconnect first.";
            *errPtr = [self badConfigError:msg];
        }
        return NO;
    }
    
    BOOL isIPv4Disabled = (config & kIPv4Disabled) ? YES : NO;
    BOOL isIPv6Disabled = (config & kIPv6Disabled) ? YES : NO;
    
    if (isIPv4Disabled && isIPv6Disabled) // Must have IPv4 or IPv6 enabled
    {
        if (errPtr)
        {
            NSString *msg = @"Both IPv4 and IPv6 have been disabled. Must enable at least one protocol first.";
            *errPtr = [self badConfigError:msg];
        }
        return NO;
    }
    
    if (interface)
    {
        NSMutableData *interface4 = nil;
        NSMutableData *interface6 = nil;
        
        [self getInterfaceAddress4:&interface4 address6:&interface6 fromDescription:interface port:0];
        
        if ((interface4 == nil) && (interface6 == nil))
        {
            if (errPtr)
            {
                NSString *msg = @"Unknown interface. Specify valid interface by name (e.g. \"en1\") or IP address.";
                *errPtr = [self badParamError:msg];
            }
            return NO;
        }
        
        if (isIPv4Disabled && (interface6 == nil))
        {
            if (errPtr)
            {
                NSString *msg = @"IPv4 has been disabled and specified interface doesn't support IPv6.";
                *errPtr = [self badParamError:msg];
            }
            return NO;
        }
        
        if (isIPv6Disabled && (interface4 == nil))
        {
            if (errPtr)
            {
                NSString *msg = @"IPv6 has been disabled and specified interface doesn't support IPv4.";
                *errPtr = [self badParamError:msg];
            }
            return NO;
        }
        
        connectInterface4 = interface4;
        connectInterface6 = interface6;
    }
    
    // Clear queues (spurious read/write requests post disconnect)
    [readQueue removeAllObjects];
    [writeQueue removeAllObjects];
    
    return YES;
}

- (BOOL)connectToHost:(NSString*)host onPort:(uint16_t)port error:(NSError **)errPtr
{
    return [self connectToHost:host onPort:port withTimeout:-1 error:errPtr];
}

- (BOOL)connectToHost:(NSString *)host
               onPort:(uint16_t)port
          withTimeout:(NSTimeInterval)timeout
                error:(NSError **)errPtr
{
    return [self connectToHost:host onPort:port viaInterface:nil withTimeout:timeout error:errPtr];
}

- (BOOL)connectToHost:(NSString *)inHost
               onPort:(uint16_t)port
         viaInterface:(NSString *)inInterface
          withTimeout:(NSTimeInterval)timeout
                error:(NSError **)errPtr
{
    LogTrace();
    
    // Just in case immutable objects were passed
    NSString *host = [inHost copy];
    NSString *interface = [inInterface copy];
    
    __block BOOL result = NO;
    __block NSError *err = nil;
    
    dispatch_block_t block = ^{ @autoreleasepool {
        
        // Check for problems with host parameter
        
        if ([host length] == 0)
        {
            NSString *msg = @"Invalid host parameter (nil or \"\"). Should be a domain name or IP address string.";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        // Run through standard pre-connect checks
        
        if (![self preConnectWithInterface:interface error:&err])
        {
            return_from_block;
        }
        
        // We've made it past all the checks.
        // It's time to start the connection process.
        
        flags |= kSocketStarted;
        
        LogVerbose(@"Dispatching DNS lookup...");
        
        // It's possible that the given host parameter is actually a NSMutableString.
        // So we want to copy it now, within this block that will be executed synchronously.
        // This way the asynchronous lookup block below doesn't have to worry about it changing.
        
        int aConnectIndex = connectIndex;
        NSString *hostCpy = [host copy];
        
        dispatch_queue_t globalConcurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
        dispatch_async(globalConcurrentQueue, ^{ @autoreleasepool {
            
            [self lookup:aConnectIndex host:hostCpy port:port];
        }});
        
        [self startConnectTimeout:timeout];
        
        result = YES;
    }};
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    if (result == NO)
    {
        if (errPtr)
            *errPtr = err;
    }
    
    return result;
}

- (BOOL)connectToAddress:(NSData *)remoteAddr error:(NSError **)errPtr
{
    return [self connectToAddress:remoteAddr viaInterface:nil withTimeout:-1 error:errPtr];
}

- (BOOL)connectToAddress:(NSData *)remoteAddr withTimeout:(NSTimeInterval)timeout error:(NSError **)errPtr
{
    return [self connectToAddress:remoteAddr viaInterface:nil withTimeout:timeout error:errPtr];
}

- (BOOL)connectToAddress:(NSData *)inRemoteAddr
            viaInterface:(NSString *)inInterface
             withTimeout:(NSTimeInterval)timeout
                   error:(NSError **)errPtr
{
    LogTrace();
    
    // Just in case immutable objects were passed
    NSData *remoteAddr = [inRemoteAddr copy];
    NSString *interface = [inInterface copy];
    
    __block BOOL result = NO;
    __block NSError *err = nil;
    
    dispatch_block_t block = ^{ @autoreleasepool {
        
        // Check for problems with remoteAddr parameter
        
        NSData *address4 = nil;
        NSData *address6 = nil;
        
        if ([remoteAddr length] >= sizeof(struct sockaddr))
        {
            const struct sockaddr *sockaddr = (const struct sockaddr *)[remoteAddr bytes];
            
            if (sockaddr->sa_family == AF_INET)
            {
                if ([remoteAddr length] == sizeof(struct sockaddr_in))
                {
                    address4 = remoteAddr;
                }
            }
            else if (sockaddr->sa_family == AF_INET6)
            {
                if ([remoteAddr length] == sizeof(struct sockaddr_in6))
                {
                    address6 = remoteAddr;
                }
            }
        }
        
        if ((address4 == nil) && (address6 == nil))
        {
            NSString *msg = @"A valid IPv4 or IPv6 address was not given";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        BOOL isIPv4Disabled = (config & kIPv4Disabled) ? YES : NO;
        BOOL isIPv6Disabled = (config & kIPv6Disabled) ? YES : NO;
        
        if (isIPv4Disabled && (address4 != nil))
        {
            NSString *msg = @"IPv4 has been disabled and an IPv4 address was passed.";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        if (isIPv6Disabled && (address6 != nil))
        {
            NSString *msg = @"IPv6 has been disabled and an IPv6 address was passed.";
            err = [self badParamError:msg];
            
            return_from_block;
        }
        
        // Run through standard pre-connect checks
        
        if (![self preConnectWithInterface:interface error:&err])
        {
            return_from_block;
        }
        
        // We've made it past all the checks.
        // It's time to start the connection process.
        
        if (![self connectWithAddress4:address4 address6:address6 error:&err])
        {
            return_from_block;
        }
        
        flags |= kSocketStarted;
        
        [self startConnectTimeout:timeout];
        
        result = YES;
    }};
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    if (result == NO)
    {
        if (errPtr)
            *errPtr = err;
    }
    
    return result;
}

- (void)lookup:(int)aConnectIndex host:(NSString *)host port:(uint16_t)port
{
    LogTrace();
    
    // This method is executed on a global concurrent queue.
    // It posts the results back to the socket queue.
    // The lookupIndex is used to ignore the results if the connect operation was cancelled or timed out.
    
    NSError *error = nil;
    
    NSData *address4 = nil;
    NSData *address6 = nil;
    
    
    if ([host isEqualToString:@"localhost"] || [host isEqualToString:@"loopback"])
    {
        // Use LOOPBACK address
        struct sockaddr_in nativeAddr;
        nativeAddr.sin_len         = sizeof(struct sockaddr_in);
        nativeAddr.sin_family      = AF_INET;
        nativeAddr.sin_port        = htons(port);
        nativeAddr.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
        memset(&(nativeAddr.sin_zero), 0, sizeof(nativeAddr.sin_zero));
        
        struct sockaddr_in6 nativeAddr6;
        nativeAddr6.sin6_len       = sizeof(struct sockaddr_in6);
        nativeAddr6.sin6_family    = AF_INET6;
        nativeAddr6.sin6_port      = htons(port);
        nativeAddr6.sin6_flowinfo  = 0;
        nativeAddr6.sin6_addr      = in6addr_loopback;
        nativeAddr6.sin6_scope_id  = 0;
        
        // Wrap the native address structures
        address4 = [NSData dataWithBytes:&nativeAddr length:sizeof(nativeAddr)];
        address6 = [NSData dataWithBytes:&nativeAddr6 length:sizeof(nativeAddr6)];
    }
    else
    {
        NSString *portStr = [NSString stringWithFormat:@"%hu", port];
        
        struct addrinfo hints, *res, *res0;
        
        memset(&hints, 0, sizeof(hints));
        hints.ai_family   = PF_UNSPEC;
        hints.ai_socktype = SOCK_STREAM;
        hints.ai_protocol = IPPROTO_TCP;
        
        int gai_error = getaddrinfo([host UTF8String], [portStr UTF8String], &hints, &res0);
        
        if (gai_error)
        {
            error = [self gaiError:gai_error];
        }
        else
        {
            for(res = res0; res; res = res->ai_next)
            {
                if ((address4 == nil) && (res->ai_family == AF_INET))
                {
                    // Found IPv4 address
                    // Wrap the native address structure
                    address4 = [NSData dataWithBytes:res->ai_addr length:res->ai_addrlen];
                }
                else if ((address6 == nil) && (res->ai_family == AF_INET6))
                {
                    // Found IPv6 address
                    // Wrap the native address structure
                    address6 = [NSData dataWithBytes:res->ai_addr length:res->ai_addrlen];
                }
            }
            freeaddrinfo(res0);
            
            if ((address4 == nil) && (address6 == nil))
            {
                error = [self gaiError:EAI_FAIL];
            }
        }
    }
    
    if (error)
    {
        dispatch_async(socketQueue, ^{ @autoreleasepool {
            
            [self lookup:aConnectIndex didFail:error];
        }});
    }
    else
    {
        dispatch_async(socketQueue, ^{ @autoreleasepool {
            
            [self lookup:aConnectIndex didSucceedWithAddress4:address4 address6:address6];
        }});
    }
}

- (void)lookup:(int)aConnectIndex didSucceedWithAddress4:(NSData *)address4 address6:(NSData *)address6
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    NSAssert(address4 || address6, @"Expected at least one valid address");
    
    if (aConnectIndex != connectIndex)
    {
        LogInfo(@"Ignoring lookupDidSucceed, already disconnected");
        
        // The connect operation has been cancelled.
        // That is, socket was disconnected, or connection has already timed out.
        return;
    }
    
    // Check for problems
    
    BOOL isIPv4Disabled = (config & kIPv4Disabled) ? YES : NO;
    BOOL isIPv6Disabled = (config & kIPv6Disabled) ? YES : NO;
    
    if (isIPv4Disabled && (address6 == nil))
    {
        NSString *msg = @"IPv4 has been disabled and DNS lookup found no IPv6 address.";
        
        [self closeWithError:[self otherError:msg]];
        return;
    }
    
    if (isIPv6Disabled && (address4 == nil))
    {
        NSString *msg = @"IPv6 has been disabled and DNS lookup found no IPv4 address.";
        
        [self closeWithError:[self otherError:msg]];
        return;
    }
    
    // Start the normal connection process
    
    NSError *err = nil;
    if (![self connectWithAddress4:address4 address6:address6 error:&err])
    {
        [self closeWithError:err];
    }
}

/**
 * This method is called if the DNS lookup fails.
 * This method is executed on the socketQueue.
 * 
 * Since the DNS lookup executed synchronously on a global concurrent queue,
 * the original connection request may have already been cancelled or timed-out by the time this method is invoked.
 * The lookupIndex tells us whether the lookup is still valid or not.
**/
- (void)lookup:(int)aConnectIndex didFail:(NSError *)error
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    
    if (aConnectIndex != connectIndex)
    {
        LogInfo(@"Ignoring lookup:didFail: - already disconnected");
        
        // The connect operation has been cancelled.
        // That is, socket was disconnected, or connection has already timed out.
        return;
    }
    
    [self endConnectTimeout];
    [self closeWithError:error];
}

- (BOOL)connectWithAddress4:(NSData *)address4 address6:(NSData *)address6 error:(NSError **)errPtr
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    LogVerbose(@"IPv4: %@:%hu", [[self class] hostFromAddress:address4], [[self class] portFromAddress:address4]);
    LogVerbose(@"IPv6: %@:%hu", [[self class] hostFromAddress:address6], [[self class] portFromAddress:address6]);
    
    // Determine socket type
    
    BOOL preferIPv6 = (config & kPreferIPv6) ? YES : NO;
    
    BOOL useIPv6 = ((preferIPv6 && address6) || (address4 == nil));
    
    // Create the socket
    
    int socketFD;
    NSData *address;
    NSData *connectInterface;
    
    if (useIPv6)
    {
        LogVerbose(@"Creating IPv6 socket");
        
        socket6FD = socket(AF_INET6, SOCK_STREAM, 0);
        
        socketFD = socket6FD;
        address = address6;
        connectInterface = connectInterface6;
    }
    else
    {
        LogVerbose(@"Creating IPv4 socket");
        
        socket4FD = socket(AF_INET, SOCK_STREAM, 0);
        
        socketFD = socket4FD;
        address = address4;
        connectInterface = connectInterface4;
    }
    
    if (socketFD == SOCKET_NULL)
    {
        if (errPtr)
            *errPtr = [self errnoErrorWithReason:@"Error in socket() function"];
        
        return NO;
    }
    
    // Bind the socket to the desired interface (if needed)
    
    if (connectInterface)
    {
        LogVerbose(@"Binding socket...");
        
        if ([[self class] portFromAddress:connectInterface] > 0)
        {
            // Since we're going to be binding to a specific port,
            // we should turn on reuseaddr to allow us to override sockets in time_wait.
            
            int reuseOn = 1;
            setsockopt(socketFD, SOL_SOCKET, SO_REUSEADDR, &reuseOn, sizeof(reuseOn));
        }
        
        const struct sockaddr *interfaceAddr = (const struct sockaddr *)[connectInterface bytes];
        
        int result = bind(socketFD, interfaceAddr, (socklen_t)[connectInterface length]);
        if (result != 0)
        {
            if (errPtr)
                *errPtr = [self errnoErrorWithReason:@"Error in bind() function"];
            
            return NO;
        }
    }
    
    // Prevent SIGPIPE signals
    
    int nosigpipe = 1;
    setsockopt(socketFD, SOL_SOCKET, SO_NOSIGPIPE, &nosigpipe, sizeof(nosigpipe));
    
    // Start the connection process in a background queue
    
    int aConnectIndex = connectIndex;
    
    dispatch_queue_t globalConcurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
    dispatch_async(globalConcurrentQueue, ^{
        
        int result = connect(socketFD, (const struct sockaddr *)[address bytes], (socklen_t)[address length]);
        if (result == 0)
        {
            dispatch_async(socketQueue, ^{ @autoreleasepool {
                
                [self didConnect:aConnectIndex];
            }});
        }
        else
        {
            NSError *error = [self errnoErrorWithReason:@"Error in connect() function"];
            
            dispatch_async(socketQueue, ^{ @autoreleasepool {
                
                [self didNotConnect:aConnectIndex error:error];
            }});
        }
    });
    
    LogVerbose(@"Connecting...");
    
    return YES;
}

- (void)didConnect:(int)aConnectIndex
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    
    if (aConnectIndex != connectIndex)
    {
        LogInfo(@"Ignoring didConnect, already disconnected");
        
        // The connect operation has been cancelled.
        // That is, socket was disconnected, or connection has already timed out.
        return;
    }
    
    flags |= kConnected;
    
    [self endConnectTimeout];
    
    #if TARGET_OS_IPHONE
    // The endConnectTimeout method executed above incremented the connectIndex.
    aConnectIndex = connectIndex;
    #endif
    
    // Setup read/write streams (as workaround for specific shortcomings in the iOS platform)
    // 
    // Note:
    // There may be configuration options that must be set by the delegate before opening the streams.
    // The primary example is the kCFStreamNetworkServiceTypeVoIP flag, which only works on an unopened stream.
    // 
    // Thus we wait until after the socket:didConnectToHost:port: delegate method has completed.
    // This gives the delegate time to properly configure the streams if needed.
    
    dispatch_block_t SetupStreamsPart1 = ^{
        #if TARGET_OS_IPHONE
        
        if (![self createReadAndWriteStream])
        {
            [self closeWithError:[self otherError:@"Error creating CFStreams"]];
            return;
        }
        
        if (![self registerForStreamCallbacksIncludingReadWrite:NO])
        {
            [self closeWithError:[self otherError:@"Error in CFStreamSetClient"]];
            return;
        }
        
        #endif
    };
    dispatch_block_t SetupStreamsPart2 = ^{
        #if TARGET_OS_IPHONE
        
        if (aConnectIndex != connectIndex)
        {
            // The socket has been disconnected.
            return;
        }
        
        if (![self addStreamsToRunLoop])
        {
            [self closeWithError:[self otherError:@"Error in CFStreamScheduleWithRunLoop"]];
            return;
        }
        
        if (![self openStreams])
        {
            [self closeWithError:[self otherError:@"Error creating CFStreams"]];
            return;
        }
        
        #endif
    };
    
    // Notify delegate
    
    NSString *host = [self connectedHost];
    uint16_t port = [self connectedPort];
    
    if (delegateQueue && [delegate respondsToSelector:@selector(socket:didConnectToHost:port:)])
    {
        SetupStreamsPart1();
        
        __strong id theDelegate = delegate;
        
        dispatch_async(delegateQueue, ^{ @autoreleasepool {
            
            [theDelegate socket:self didConnectToHost:host port:port];
            
            dispatch_async(socketQueue, ^{ @autoreleasepool {
                
                SetupStreamsPart2();
            }});
        }});
    }
    else
    {
        SetupStreamsPart1();
        SetupStreamsPart2();
    }
        
    // Get the connected socket
    
    int socketFD = (socket4FD != SOCKET_NULL) ? socket4FD : socket6FD;
    
    // Enable non-blocking IO on the socket
    
    int result = fcntl(socketFD, F_SETFL, O_NONBLOCK);
    if (result == -1)
    {
        NSString *errMsg = @"Error enabling non-blocking IO on socket (fcntl)";
        [self closeWithError:[self otherError:errMsg]];
        
        return;
    }
    
    // Setup our read/write sources
    
    [self setupReadAndWriteSourcesForNewlyConnectedSocket:socketFD];
    
    // Dequeue any pending read/write requests
    
    [self maybeDequeueRead];
    [self maybeDequeueWrite];
}

- (void)didNotConnect:(int)aConnectIndex error:(NSError *)error
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    
    if (aConnectIndex != connectIndex)
    {
        LogInfo(@"Ignoring didNotConnect, already disconnected");
        
        // The connect operation has been cancelled.
        // That is, socket was disconnected, or connection has already timed out.
        return;
    }
    
    [self closeWithError:error];
}

- (void)startConnectTimeout:(NSTimeInterval)timeout
{
    if (timeout >= 0.0)
    {
        connectTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, socketQueue);
        
        dispatch_source_set_event_handler(connectTimer, ^{ @autoreleasepool {
            
            [self doConnectTimeout];
        }});
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        dispatch_source_t theConnectTimer = connectTimer;
        dispatch_source_set_cancel_handler(connectTimer, ^{
            LogVerbose(@"dispatch_release(connectTimer)");
            dispatch_release(theConnectTimer);
        });
        #endif
        
        dispatch_time_t tt = dispatch_time(DISPATCH_TIME_NOW, (timeout * NSEC_PER_SEC));
        dispatch_source_set_timer(connectTimer, tt, DISPATCH_TIME_FOREVER, 0);
        
        dispatch_resume(connectTimer);
    }
}

- (void)endConnectTimeout
{
    LogTrace();
    
    if (connectTimer)
    {
        dispatch_source_cancel(connectTimer);
        connectTimer = NULL;
    }
    
    // Increment connectIndex.
    // This will prevent us from processing results from any related background asynchronous operations.
    // 
    // Note: This should be called from close method even if connectTimer is NULL.
    // This is because one might disconnect a socket prior to a successful connection which had no timeout.
    
    connectIndex++;
    
    if (connectInterface4)
    {
        connectInterface4 = nil;
    }
    if (connectInterface6)
    {
        connectInterface6 = nil;
    }
}

- (void)doConnectTimeout
{
    LogTrace();
    
    [self endConnectTimeout];
    [self closeWithError:[self connectTimeoutError]];
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Disconnecting
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (void)closeWithError:(NSError *)error
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    
    [self endConnectTimeout];
    
    if (currentRead != nil)  [self endCurrentRead];
    if (currentWrite != nil) [self endCurrentWrite];
    
    [readQueue removeAllObjects];
    [writeQueue removeAllObjects];
    
    [preBuffer reset];
    
    #if TARGET_OS_IPHONE
    {
        if (readStream || writeStream)
        {
            [self removeStreamsFromRunLoop];
            
            if (readStream)
            {
                CFReadStreamSetClient(readStream, kCFStreamEventNone, NULL, NULL);
                CFReadStreamClose(readStream);
                CFRelease(readStream);
                readStream = NULL;
            }
            if (writeStream)
            {
                CFWriteStreamSetClient(writeStream, kCFStreamEventNone, NULL, NULL);
                CFWriteStreamClose(writeStream);
                CFRelease(writeStream);
                writeStream = NULL;
            }
        }
    }
    #endif
    #if SECURE_TRANSPORT_MAYBE_AVAILABLE
    {
        [sslPreBuffer reset];
        sslErrCode = noErr;
        
        if (sslContext)
        {
            // Getting a linker error here about the SSLx() functions?
            // You need to add the Security Framework to your application.
            
            SSLClose(sslContext);
            
            #if TARGET_OS_IPHONE
            CFRelease(sslContext);
            #else
            SSLDisposeContext(sslContext);
            #endif
            
            sslContext = NULL;
        }
    }
    #endif
    
    // For some crazy reason (in my opinion), cancelling a dispatch source doesn't
    // invoke the cancel handler if the dispatch source is paused.
    // So we have to unpause the source if needed.
    // This allows the cancel handler to be run, which in turn releases the source and closes the socket.
    
    if (!accept4Source && !accept6Source && !readSource && !writeSource)
    {
        LogVerbose(@"manually closing close");

        if (socket4FD != SOCKET_NULL)
        {
            LogVerbose(@"close(socket4FD)");
            close(socket4FD);
            socket4FD = SOCKET_NULL;
        }

        if (socket6FD != SOCKET_NULL)
        {
            LogVerbose(@"close(socket6FD)");
            close(socket6FD);
            socket6FD = SOCKET_NULL;
        }
    }
    else
    {
        if (accept4Source)
        {
            LogVerbose(@"dispatch_source_cancel(accept4Source)");
            dispatch_source_cancel(accept4Source);
            
            // We never suspend accept4Source
            
            accept4Source = NULL;
        }
        
        if (accept6Source)
        {
            LogVerbose(@"dispatch_source_cancel(accept6Source)");
            dispatch_source_cancel(accept6Source);
            
            // We never suspend accept6Source
            
            accept6Source = NULL;
        }
    
        if (readSource)
        {
            LogVerbose(@"dispatch_source_cancel(readSource)");
            dispatch_source_cancel(readSource);
            
            [self resumeReadSource];
            
            readSource = NULL;
        }
        
        if (writeSource)
        {
            LogVerbose(@"dispatch_source_cancel(writeSource)");
            dispatch_source_cancel(writeSource);
            
            [self resumeWriteSource];
            
            writeSource = NULL;
        }
        
        // The sockets will be closed by the cancel handlers of the corresponding source
        
        socket4FD = SOCKET_NULL;
        socket6FD = SOCKET_NULL;
    }
    
    // If the client has passed the connect/accept method, then the connection has at least begun.
    // Notify delegate that it is now ending.
    BOOL shouldCallDelegate = (flags & kSocketStarted);
    
    // Clear stored socket info and all flags (config remains as is)
    socketFDBytesAvailable = 0;
    flags = 0;
    
    if (shouldCallDelegate)
    {
        if (delegateQueue && [delegate respondsToSelector: @selector(socketDidDisconnect:withError:)])
        {
            __strong id theDelegate = delegate;
            
            dispatch_async(delegateQueue, ^{ @autoreleasepool {
                
                [theDelegate socketDidDisconnect:self withError:error];
            }});
        }   
    }
}

- (void)disconnect
{
    dispatch_block_t block = ^{ @autoreleasepool {
        
        if (flags & kSocketStarted)
        {
            [self closeWithError:nil];
        }
    }};
    
    // Synchronous disconnection, as documented in the header file
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
}

- (void)disconnectAfterReading
{
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        if (flags & kSocketStarted)
        {
            flags |= (kForbidReadsWrites | kDisconnectAfterReads);
            [self maybeClose];
        }
    }});
}

- (void)disconnectAfterWriting
{
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        if (flags & kSocketStarted)
        {
            flags |= (kForbidReadsWrites | kDisconnectAfterWrites);
            [self maybeClose];
        }
    }});
}

- (void)disconnectAfterReadingAndWriting
{
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        if (flags & kSocketStarted)
        {
            flags |= (kForbidReadsWrites | kDisconnectAfterReads | kDisconnectAfterWrites);
            [self maybeClose];
        }
    }});
}

/**
 * Closes the socket if possible.
 * That is, if all writes have completed, and we're set to disconnect after writing,
 * or if all reads have completed, and we're set to disconnect after reading.
**/
- (void)maybeClose
{
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    BOOL shouldClose = NO;
    
    if (flags & kDisconnectAfterReads)
    {
        if (([readQueue count] == 0) && (currentRead == nil))
        {
            if (flags & kDisconnectAfterWrites)
            {
                if (([writeQueue count] == 0) && (currentWrite == nil))
                {
                    shouldClose = YES;
                }
            }
            else
            {
                shouldClose = YES;
            }
        }
    }
    else if (flags & kDisconnectAfterWrites)
    {
        if (([writeQueue count] == 0) && (currentWrite == nil))
        {
            shouldClose = YES;
        }
    }
    
    if (shouldClose)
    {
        [self closeWithError:nil];
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Errors
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (NSError *)badConfigError:(NSString *)errMsg
{
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketBadConfigError userInfo:userInfo];
}

- (NSError *)badParamError:(NSString *)errMsg
{
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketBadParamError userInfo:userInfo];
}

- (NSError *)gaiError:(int)gai_error
{
    NSString *errMsg = [NSString stringWithCString:gai_strerror(gai_error) encoding:NSASCIIStringEncoding];
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:@"kCFStreamErrorDomainNetDB" code:gai_error userInfo:userInfo];
}

- (NSError *)errnoErrorWithReason:(NSString *)reason
{
    NSString *errMsg = [NSString stringWithUTF8String:strerror(errno)];
    NSDictionary *userInfo = [NSDictionary dictionaryWithObjectsAndKeys:errMsg, NSLocalizedDescriptionKey,
                                                                        reason, NSLocalizedFailureReasonErrorKey, nil];
    
    return [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:userInfo];
}

- (NSError *)errnoError
{
    NSString *errMsg = [NSString stringWithUTF8String:strerror(errno)];
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:NSPOSIXErrorDomain code:errno userInfo:userInfo];
}

- (NSError *)sslError:(OSStatus)ssl_error
{
    NSString *msg = @"Error code definition can be found in Apple's SecureTransport.h";
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:msg forKey:NSLocalizedRecoverySuggestionErrorKey];
    
    return [NSError errorWithDomain:@"kCFStreamErrorDomainSSL" code:ssl_error userInfo:userInfo];
}

- (NSError *)connectTimeoutError
{
    NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncSocketConnectTimeoutError",
                                                         @"GCDAsyncSocket", [NSBundle mainBundle],
                                                         @"Attempt to connect to host timed out", nil);
    
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketConnectTimeoutError userInfo:userInfo];
}

/**
 * Returns a standard AsyncSocket maxed out error.
**/
- (NSError *)readMaxedOutError
{
    NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncSocketReadMaxedOutError",
                                                         @"GCDAsyncSocket", [NSBundle mainBundle],
                                                         @"Read operation reached set maximum length", nil);
    
    NSDictionary *info = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketReadMaxedOutError userInfo:info];
}

/**
 * Returns a standard AsyncSocket write timeout error.
**/
- (NSError *)readTimeoutError
{
    NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncSocketReadTimeoutError",
                                                         @"GCDAsyncSocket", [NSBundle mainBundle],
                                                         @"Read operation timed out", nil);
    
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketReadTimeoutError userInfo:userInfo];
}

/**
 * Returns a standard AsyncSocket write timeout error.
**/
- (NSError *)writeTimeoutError
{
    NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncSocketWriteTimeoutError",
                                                         @"GCDAsyncSocket", [NSBundle mainBundle],
                                                         @"Write operation timed out", nil);
    
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketWriteTimeoutError userInfo:userInfo];
}

- (NSError *)connectionClosedError
{
    NSString *errMsg = NSLocalizedStringWithDefaultValue(@"GCDAsyncSocketClosedError",
                                                         @"GCDAsyncSocket", [NSBundle mainBundle],
                                                         @"Socket closed by remote peer", nil);
    
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketClosedError userInfo:userInfo];
}

- (NSError *)otherError:(NSString *)errMsg
{
    NSDictionary *userInfo = [NSDictionary dictionaryWithObject:errMsg forKey:NSLocalizedDescriptionKey];
    
    return [NSError errorWithDomain:GCDAsyncSocketErrorDomain code:GCDAsyncSocketOtherError userInfo:userInfo];
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Diagnostics
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (BOOL)isDisconnected
{
    __block BOOL result = NO;
    
    dispatch_block_t block = ^{
        result = (flags & kSocketStarted) ? NO : YES;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

- (BOOL)isConnected
{
    __block BOOL result = NO;
    
    dispatch_block_t block = ^{
        result = (flags & kConnected) ? YES : NO;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

- (NSString *)connectedHost
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        if (socket4FD != SOCKET_NULL)
            return [self connectedHostFromSocket4:socket4FD];
        if (socket6FD != SOCKET_NULL)
            return [self connectedHostFromSocket6:socket6FD];
        
        return nil;
    }
    else
    {
        __block NSString *result = nil;
        
        dispatch_sync(socketQueue, ^{ @autoreleasepool {
            
            if (socket4FD != SOCKET_NULL)
                result = [self connectedHostFromSocket4:socket4FD];
            else if (socket6FD != SOCKET_NULL)
                result = [self connectedHostFromSocket6:socket6FD];
        }});
        
        return result;
    }
}

- (uint16_t)connectedPort
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        if (socket4FD != SOCKET_NULL)
            return [self connectedPortFromSocket4:socket4FD];
        if (socket6FD != SOCKET_NULL)
            return [self connectedPortFromSocket6:socket6FD];
        
        return 0;
    }
    else
    {
        __block uint16_t result = 0;
        
        dispatch_sync(socketQueue, ^{
            // No need for autorelease pool
            
            if (socket4FD != SOCKET_NULL)
                result = [self connectedPortFromSocket4:socket4FD];
            else if (socket6FD != SOCKET_NULL)
                result = [self connectedPortFromSocket6:socket6FD];
        });
        
        return result;
    }
}

- (NSString *)localHost
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        if (socket4FD != SOCKET_NULL)
            return [self localHostFromSocket4:socket4FD];
        if (socket6FD != SOCKET_NULL)
            return [self localHostFromSocket6:socket6FD];
        
        return nil;
    }
    else
    {
        __block NSString *result = nil;
        
        dispatch_sync(socketQueue, ^{ @autoreleasepool {
            
            if (socket4FD != SOCKET_NULL)
                result = [self localHostFromSocket4:socket4FD];
            else if (socket6FD != SOCKET_NULL)
                result = [self localHostFromSocket6:socket6FD];
        }});
        
        return result;
    }
}

- (uint16_t)localPort
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        if (socket4FD != SOCKET_NULL)
            return [self localPortFromSocket4:socket4FD];
        if (socket6FD != SOCKET_NULL)
            return [self localPortFromSocket6:socket6FD];
        
        return 0;
    }
    else
    {
        __block uint16_t result = 0;
        
        dispatch_sync(socketQueue, ^{
            // No need for autorelease pool
            
            if (socket4FD != SOCKET_NULL)
                result = [self localPortFromSocket4:socket4FD];
            else if (socket6FD != SOCKET_NULL)
                result = [self localPortFromSocket6:socket6FD];
        });
        
        return result;
    }
}

- (NSString *)connectedHost4
{
    if (socket4FD != SOCKET_NULL)
        return [self connectedHostFromSocket4:socket4FD];
    
    return nil;
}

- (NSString *)connectedHost6
{
    if (socket6FD != SOCKET_NULL)
        return [self connectedHostFromSocket6:socket6FD];
    
    return nil;
}

- (uint16_t)connectedPort4
{
    if (socket4FD != SOCKET_NULL)
        return [self connectedPortFromSocket4:socket4FD];
    
    return 0;
}

- (uint16_t)connectedPort6
{
    if (socket6FD != SOCKET_NULL)
        return [self connectedPortFromSocket6:socket6FD];
    
    return 0;
}

- (NSString *)localHost4
{
    if (socket4FD != SOCKET_NULL)
        return [self localHostFromSocket4:socket4FD];
    
    return nil;
}

- (NSString *)localHost6
{
    if (socket6FD != SOCKET_NULL)
        return [self localHostFromSocket6:socket6FD];
    
    return nil;
}

- (uint16_t)localPort4
{
    if (socket4FD != SOCKET_NULL)
        return [self localPortFromSocket4:socket4FD];
    
    return 0;
}

- (uint16_t)localPort6
{
    if (socket6FD != SOCKET_NULL)
        return [self localPortFromSocket6:socket6FD];
    
    return 0;
}

- (NSString *)connectedHostFromSocket4:(int)socketFD
{
    struct sockaddr_in sockaddr4;
    socklen_t sockaddr4len = sizeof(sockaddr4);
    
    if (getpeername(socketFD, (struct sockaddr *)&sockaddr4, &sockaddr4len) < 0)
    {
        return nil;
    }
    return [[self class] hostFromSockaddr4:&sockaddr4];
}

- (NSString *)connectedHostFromSocket6:(int)socketFD
{
    struct sockaddr_in6 sockaddr6;
    socklen_t sockaddr6len = sizeof(sockaddr6);
    
    if (getpeername(socketFD, (struct sockaddr *)&sockaddr6, &sockaddr6len) < 0)
    {
        return nil;
    }
    return [[self class] hostFromSockaddr6:&sockaddr6];
}

- (uint16_t)connectedPortFromSocket4:(int)socketFD
{
    struct sockaddr_in sockaddr4;
    socklen_t sockaddr4len = sizeof(sockaddr4);
    
    if (getpeername(socketFD, (struct sockaddr *)&sockaddr4, &sockaddr4len) < 0)
    {
        return 0;
    }
    return [[self class] portFromSockaddr4:&sockaddr4];
}

- (uint16_t)connectedPortFromSocket6:(int)socketFD
{
    struct sockaddr_in6 sockaddr6;
    socklen_t sockaddr6len = sizeof(sockaddr6);
    
    if (getpeername(socketFD, (struct sockaddr *)&sockaddr6, &sockaddr6len) < 0)
    {
        return 0;
    }
    return [[self class] portFromSockaddr6:&sockaddr6];
}

- (NSString *)localHostFromSocket4:(int)socketFD
{
    struct sockaddr_in sockaddr4;
    socklen_t sockaddr4len = sizeof(sockaddr4);
    
    if (getsockname(socketFD, (struct sockaddr *)&sockaddr4, &sockaddr4len) < 0)
    {
        return nil;
    }
    return [[self class] hostFromSockaddr4:&sockaddr4];
}

- (NSString *)localHostFromSocket6:(int)socketFD
{
    struct sockaddr_in6 sockaddr6;
    socklen_t sockaddr6len = sizeof(sockaddr6);
    
    if (getsockname(socketFD, (struct sockaddr *)&sockaddr6, &sockaddr6len) < 0)
    {
        return nil;
    }
    return [[self class] hostFromSockaddr6:&sockaddr6];
}

- (uint16_t)localPortFromSocket4:(int)socketFD
{
    struct sockaddr_in sockaddr4;
    socklen_t sockaddr4len = sizeof(sockaddr4);
    
    if (getsockname(socketFD, (struct sockaddr *)&sockaddr4, &sockaddr4len) < 0)
    {
        return 0;
    }
    return [[self class] portFromSockaddr4:&sockaddr4];
}

- (uint16_t)localPortFromSocket6:(int)socketFD
{
    struct sockaddr_in6 sockaddr6;
    socklen_t sockaddr6len = sizeof(sockaddr6);
    
    if (getsockname(socketFD, (struct sockaddr *)&sockaddr6, &sockaddr6len) < 0)
    {
        return 0;
    }
    return [[self class] portFromSockaddr6:&sockaddr6];
}

- (NSData *)connectedAddress
{
    __block NSData *result = nil;
    
    dispatch_block_t block = ^{
        if (socket4FD != SOCKET_NULL)
        {
            struct sockaddr_in sockaddr4;
            socklen_t sockaddr4len = sizeof(sockaddr4);
            
            if (getpeername(socket4FD, (struct sockaddr *)&sockaddr4, &sockaddr4len) == 0)
            {
                result = [[NSData alloc] initWithBytes:&sockaddr4 length:sockaddr4len];
            }
        }
        
        if (socket6FD != SOCKET_NULL)
        {
            struct sockaddr_in6 sockaddr6;
            socklen_t sockaddr6len = sizeof(sockaddr6);
            
            if (getpeername(socket6FD, (struct sockaddr *)&sockaddr6, &sockaddr6len) == 0)
            {
                result = [[NSData alloc] initWithBytes:&sockaddr6 length:sockaddr6len];
            }
        }
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

- (NSData *)localAddress
{
    __block NSData *result = nil;
    
    dispatch_block_t block = ^{
        if (socket4FD != SOCKET_NULL)
        {
            struct sockaddr_in sockaddr4;
            socklen_t sockaddr4len = sizeof(sockaddr4);
            
            if (getsockname(socket4FD, (struct sockaddr *)&sockaddr4, &sockaddr4len) == 0)
            {
                result = [[NSData alloc] initWithBytes:&sockaddr4 length:sockaddr4len];
            }
        }
        
        if (socket6FD != SOCKET_NULL)
        {
            struct sockaddr_in6 sockaddr6;
            socklen_t sockaddr6len = sizeof(sockaddr6);
            
            if (getsockname(socket6FD, (struct sockaddr *)&sockaddr6, &sockaddr6len) == 0)
            {
                result = [[NSData alloc] initWithBytes:&sockaddr6 length:sockaddr6len];
            }
        }
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

- (BOOL)isIPv4
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return (socket4FD != SOCKET_NULL);
    }
    else
    {
        __block BOOL result = NO;
        
        dispatch_sync(socketQueue, ^{
            result = (socket4FD != SOCKET_NULL);
        });
        
        return result;
    }
}

- (BOOL)isIPv6
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return (socket6FD != SOCKET_NULL);
    }
    else
    {
        __block BOOL result = NO;
        
        dispatch_sync(socketQueue, ^{
            result = (socket6FD != SOCKET_NULL);
        });
        
        return result;
    }
}

- (BOOL)isSecure
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return (flags & kSocketSecure) ? YES : NO;
    }
    else
    {
        __block BOOL result;
        
        dispatch_sync(socketQueue, ^{
            result = (flags & kSocketSecure) ? YES : NO;
        });
        
        return result;
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Utilities
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * Finds the address of an interface description.
 * An inteface description may be an interface name (en0, en1, lo0) or corresponding IP (192.168.4.34).
 * 
 * The interface description may optionally contain a port number at the end, separated by a colon.
 * If a non-zero port parameter is provided, any port number in the interface description is ignored.
 * 
 * The returned value is a 'struct sockaddr' wrapped in an NSMutableData object.
**/
- (void)getInterfaceAddress4:(NSMutableData **)interfaceAddr4Ptr
                    address6:(NSMutableData **)interfaceAddr6Ptr
             fromDescription:(NSString *)interfaceDescription
                        port:(uint16_t)port
{
    NSMutableData *addr4 = nil;
    NSMutableData *addr6 = nil;
    
    NSString *interface = nil;
    
    NSArray *components = [interfaceDescription componentsSeparatedByString:@":"];
    if ([components count] > 0)
    {
        NSString *temp = [components objectAtIndex:0];
        if ([temp length] > 0)
        {
            interface = temp;
        }
    }
    if ([components count] > 1 && port == 0)
    {
        long portL = strtol([[components objectAtIndex:1] UTF8String], NULL, 10);
        
        if (portL > 0 && portL <= UINT16_MAX)
        {
            port = (uint16_t)portL;
        }
    }
    
    if (interface == nil)
    {
        // ANY address
        
        struct sockaddr_in sockaddr4;
        memset(&sockaddr4, 0, sizeof(sockaddr4));
        
        sockaddr4.sin_len         = sizeof(sockaddr4);
        sockaddr4.sin_family      = AF_INET;
        sockaddr4.sin_port        = htons(port);
        sockaddr4.sin_addr.s_addr = htonl(INADDR_ANY);
        
        struct sockaddr_in6 sockaddr6;
        memset(&sockaddr6, 0, sizeof(sockaddr6));
        
        sockaddr6.sin6_len       = sizeof(sockaddr6);
        sockaddr6.sin6_family    = AF_INET6;
        sockaddr6.sin6_port      = htons(port);
        sockaddr6.sin6_addr      = in6addr_any;
        
        addr4 = [NSMutableData dataWithBytes:&sockaddr4 length:sizeof(sockaddr4)];
        addr6 = [NSMutableData dataWithBytes:&sockaddr6 length:sizeof(sockaddr6)];
    }
    else if ([interface isEqualToString:@"localhost"] || [interface isEqualToString:@"loopback"])
    {
        // LOOPBACK address
        
        struct sockaddr_in sockaddr4;
        memset(&sockaddr4, 0, sizeof(sockaddr4));
        
        sockaddr4.sin_len         = sizeof(sockaddr4);
        sockaddr4.sin_family      = AF_INET;
        sockaddr4.sin_port        = htons(port);
        sockaddr4.sin_addr.s_addr = htonl(INADDR_LOOPBACK);
        
        struct sockaddr_in6 sockaddr6;
        memset(&sockaddr6, 0, sizeof(sockaddr6));
        
        sockaddr6.sin6_len       = sizeof(sockaddr6);
        sockaddr6.sin6_family    = AF_INET6;
        sockaddr6.sin6_port      = htons(port);
        sockaddr6.sin6_addr      = in6addr_loopback;
        
        addr4 = [NSMutableData dataWithBytes:&sockaddr4 length:sizeof(sockaddr4)];
        addr6 = [NSMutableData dataWithBytes:&sockaddr6 length:sizeof(sockaddr6)];
    }
    else
    {
        const char *iface = [interface UTF8String];
        
        struct ifaddrs *addrs;
        const struct ifaddrs *cursor;
        
        if ((getifaddrs(&addrs) == 0))
        {
            cursor = addrs;
            while (cursor != NULL)
            {
                if ((addr4 == nil) && (cursor->ifa_addr->sa_family == AF_INET))
                {
                    // IPv4
                    
                    struct sockaddr_in nativeAddr4;
                    memcpy(&nativeAddr4, cursor->ifa_addr, sizeof(nativeAddr4));
                    
                    if (strcmp(cursor->ifa_name, iface) == 0)
                    {
                        // Name match
                        
                        nativeAddr4.sin_port = htons(port);
                        
                        addr4 = [NSMutableData dataWithBytes:&nativeAddr4 length:sizeof(nativeAddr4)];
                    }
                    else
                    {
                        char ip[INET_ADDRSTRLEN];
                        
                        const char *conversion = inet_ntop(AF_INET, &nativeAddr4.sin_addr, ip, sizeof(ip));
                        
                        if ((conversion != NULL) && (strcmp(ip, iface) == 0))
                        {
                            // IP match
                            
                            nativeAddr4.sin_port = htons(port);
                            
                            addr4 = [NSMutableData dataWithBytes:&nativeAddr4 length:sizeof(nativeAddr4)];
                        }
                    }
                }
                else if ((addr6 == nil) && (cursor->ifa_addr->sa_family == AF_INET6))
                {
                    // IPv6
                    
                    struct sockaddr_in6 nativeAddr6;
                    memcpy(&nativeAddr6, cursor->ifa_addr, sizeof(nativeAddr6));
                    
                    if (strcmp(cursor->ifa_name, iface) == 0)
                    {
                        // Name match
                        
                        nativeAddr6.sin6_port = htons(port);
                        
                        addr6 = [NSMutableData dataWithBytes:&nativeAddr6 length:sizeof(nativeAddr6)];
                    }
                    else
                    {
                        char ip[INET6_ADDRSTRLEN];
                        
                        const char *conversion = inet_ntop(AF_INET6, &nativeAddr6.sin6_addr, ip, sizeof(ip));
                        
                        if ((conversion != NULL) && (strcmp(ip, iface) == 0))
                        {
                            // IP match
                            
                            nativeAddr6.sin6_port = htons(port);
                            
                            addr6 = [NSMutableData dataWithBytes:&nativeAddr6 length:sizeof(nativeAddr6)];
                        }
                    }
                }
                
                cursor = cursor->ifa_next;
            }
            
            freeifaddrs(addrs);
        }
    }
    
    if (interfaceAddr4Ptr) *interfaceAddr4Ptr = addr4;
    if (interfaceAddr6Ptr) *interfaceAddr6Ptr = addr6;
}

- (void)setupReadAndWriteSourcesForNewlyConnectedSocket:(int)socketFD
{
    readSource = dispatch_source_create(DISPATCH_SOURCE_TYPE_READ, socketFD, 0, socketQueue);
    writeSource = dispatch_source_create(DISPATCH_SOURCE_TYPE_WRITE, socketFD, 0, socketQueue);
    
    // Setup event handlers
    
    dispatch_source_set_event_handler(readSource, ^{ @autoreleasepool {
        
        LogVerbose(@"readEventBlock");
        
        socketFDBytesAvailable = dispatch_source_get_data(readSource);
        LogVerbose(@"socketFDBytesAvailable: %lu", socketFDBytesAvailable);
        
        if (socketFDBytesAvailable > 0)
            [self doReadData];
        else
            [self doReadEOF];
    }});
    
    dispatch_source_set_event_handler(writeSource, ^{ @autoreleasepool {
        
        LogVerbose(@"writeEventBlock");
        
        flags |= kSocketCanAcceptBytes;
        [self doWriteData];
    }});
    
    // Setup cancel handlers
    
    __block int socketFDRefCount = 2;
    
    #if NEEDS_DISPATCH_RETAIN_RELEASE
    dispatch_source_t theReadSource = readSource;
    dispatch_source_t theWriteSource = writeSource;
    #endif
    
    dispatch_source_set_cancel_handler(readSource, ^{
        
        LogVerbose(@"readCancelBlock");
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        LogVerbose(@"dispatch_release(readSource)");
        dispatch_release(theReadSource);
        #endif
        
        if (--socketFDRefCount == 0)
        {
            LogVerbose(@"close(socketFD)");
            close(socketFD);
        }
    });
    
    dispatch_source_set_cancel_handler(writeSource, ^{
        
        LogVerbose(@"writeCancelBlock");
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        LogVerbose(@"dispatch_release(writeSource)");
        dispatch_release(theWriteSource);
        #endif
        
        if (--socketFDRefCount == 0)
        {
            LogVerbose(@"close(socketFD)");
            close(socketFD);
        }
    });
    
    // We will not be able to read until data arrives.
    // But we should be able to write immediately.
    
    socketFDBytesAvailable = 0;
    flags &= ~kReadSourceSuspended;
    
    LogVerbose(@"dispatch_resume(readSource)");
    dispatch_resume(readSource);
    
    flags |= kSocketCanAcceptBytes;
    flags |= kWriteSourceSuspended;
}

- (BOOL)usingCFStreamForTLS
{
    #if TARGET_OS_IPHONE
    {   
        if ((flags & kSocketSecure) && (flags & kUsingCFStreamForTLS))
        {
            // Due to the fact that Apple doesn't give us the full power of SecureTransport on iOS,
            // we are relegated to using the slower, less powerful, and RunLoop based CFStream API. :( Boo!
            // 
            // Thus we're not able to use the GCD read/write sources in this particular scenario.
            
            return YES;
        }
    }
    #endif
    
    return NO;
}

- (BOOL)usingSecureTransportForTLS
{
    #if TARGET_OS_IPHONE
    {
        return ![self usingCFStreamForTLS];
    }
    #endif
    
    return YES;
}

- (void)suspendReadSource
{
    if (!(flags & kReadSourceSuspended))
    {
        LogVerbose(@"dispatch_suspend(readSource)");
        
        dispatch_suspend(readSource);
        flags |= kReadSourceSuspended;
    }
}

- (void)resumeReadSource
{
    if (flags & kReadSourceSuspended)
    {
        LogVerbose(@"dispatch_resume(readSource)");
        
        dispatch_resume(readSource);
        flags &= ~kReadSourceSuspended;
    }
}

- (void)suspendWriteSource
{
    if (!(flags & kWriteSourceSuspended))
    {
        LogVerbose(@"dispatch_suspend(writeSource)");
        
        dispatch_suspend(writeSource);
        flags |= kWriteSourceSuspended;
    }
}

- (void)resumeWriteSource
{
    if (flags & kWriteSourceSuspended)
    {
        LogVerbose(@"dispatch_resume(writeSource)");
        
        dispatch_resume(writeSource);
        flags &= ~kWriteSourceSuspended;
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Reading
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (void)readDataWithTimeout:(NSTimeInterval)timeout tag:(long)tag
{
    [self readDataWithTimeout:timeout buffer:nil bufferOffset:0 maxLength:0 tag:tag];
}

- (void)readDataWithTimeout:(NSTimeInterval)timeout
                     buffer:(NSMutableData *)buffer
               bufferOffset:(NSUInteger)offset
                        tag:(long)tag
{
    [self readDataWithTimeout:timeout buffer:buffer bufferOffset:offset maxLength:0 tag:tag];
}

- (void)readDataWithTimeout:(NSTimeInterval)timeout
                     buffer:(NSMutableData *)buffer
               bufferOffset:(NSUInteger)offset
                  maxLength:(NSUInteger)length
                        tag:(long)tag
{
    if (offset > [buffer length]) {
        LogWarn(@"Cannot read: offset > [buffer length]");
        return;
    }
    
    GCDAsyncReadPacket *packet = [[GCDAsyncReadPacket alloc] initWithData:buffer
                                                              startOffset:offset
                                                                maxLength:length
                                                                  timeout:timeout
                                                               readLength:0
                                                               terminator:nil
                                                                      tag:tag];
    
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        LogTrace();
        
        if ((flags & kSocketStarted) && !(flags & kForbidReadsWrites))
        {
            [readQueue addObject:packet];
            [self maybeDequeueRead];
        }
    }});
    
    // Do not rely on the block being run in order to release the packet,
    // as the queue might get released without the block completing.
}

- (void)readDataToLength:(NSUInteger)length withTimeout:(NSTimeInterval)timeout tag:(long)tag
{
    [self readDataToLength:length withTimeout:timeout buffer:nil bufferOffset:0 tag:tag];
}

- (void)readDataToLength:(NSUInteger)length
             withTimeout:(NSTimeInterval)timeout
                  buffer:(NSMutableData *)buffer
            bufferOffset:(NSUInteger)offset
                     tag:(long)tag
{
    if (length == 0) {
        LogWarn(@"Cannot read: length == 0");
        return;
    }
    if (offset > [buffer length]) {
        LogWarn(@"Cannot read: offset > [buffer length]");
        return;
    }
    
    GCDAsyncReadPacket *packet = [[GCDAsyncReadPacket alloc] initWithData:buffer
                                                              startOffset:offset
                                                                maxLength:0
                                                                  timeout:timeout
                                                               readLength:length
                                                               terminator:nil
                                                                      tag:tag];
    
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        LogTrace();
        
        if ((flags & kSocketStarted) && !(flags & kForbidReadsWrites))
        {
            [readQueue addObject:packet];
            [self maybeDequeueRead];
        }
    }});
    
    // Do not rely on the block being run in order to release the packet,
    // as the queue might get released without the block completing.
}

- (void)readDataToData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag
{
    [self readDataToData:data withTimeout:timeout buffer:nil bufferOffset:0 maxLength:0 tag:tag];
}

- (void)readDataToData:(NSData *)data
           withTimeout:(NSTimeInterval)timeout
                buffer:(NSMutableData *)buffer
          bufferOffset:(NSUInteger)offset
                   tag:(long)tag
{
    [self readDataToData:data withTimeout:timeout buffer:buffer bufferOffset:offset maxLength:0 tag:tag];
}

- (void)readDataToData:(NSData *)data withTimeout:(NSTimeInterval)timeout maxLength:(NSUInteger)length tag:(long)tag
{
    [self readDataToData:data withTimeout:timeout buffer:nil bufferOffset:0 maxLength:length tag:tag];
}

- (void)readDataToData:(NSData *)data
           withTimeout:(NSTimeInterval)timeout
                buffer:(NSMutableData *)buffer
          bufferOffset:(NSUInteger)offset
             maxLength:(NSUInteger)maxLength
                   tag:(long)tag
{
    if ([data length] == 0) {
        LogWarn(@"Cannot read: [data length] == 0");
        return;
    }
    if (offset > [buffer length]) {
        LogWarn(@"Cannot read: offset > [buffer length]");
        return;
    }
    if (maxLength > 0 && maxLength < [data length]) {
        LogWarn(@"Cannot read: maxLength > 0 && maxLength < [data length]");
        return;
    }
    
    GCDAsyncReadPacket *packet = [[GCDAsyncReadPacket alloc] initWithData:buffer
                                                              startOffset:offset
                                                                maxLength:maxLength
                                                                  timeout:timeout
                                                               readLength:0
                                                               terminator:data
                                                                      tag:tag];
    
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        LogTrace();
        
        if ((flags & kSocketStarted) && !(flags & kForbidReadsWrites))
        {
            [readQueue addObject:packet];
            [self maybeDequeueRead];
        }
    }});
    
    // Do not rely on the block being run in order to release the packet,
    // as the queue might get released without the block completing.
}

- (float)progressOfReadReturningTag:(long *)tagPtr bytesDone:(NSUInteger *)donePtr total:(NSUInteger *)totalPtr
{
    __block float result = 0.0F;
    
    dispatch_block_t block = ^{
        
        if (!currentRead || ![currentRead isKindOfClass:[GCDAsyncReadPacket class]])
        {
            // We're not reading anything right now.
            
            if (tagPtr != NULL)   *tagPtr = 0;
            if (donePtr != NULL)  *donePtr = 0;
            if (totalPtr != NULL) *totalPtr = 0;
            
            result = NAN;
        }
        else
        {
            // It's only possible to know the progress of our read if we're reading to a certain length.
            // If we're reading to data, we of course have no idea when the data will arrive.
            // If we're reading to timeout, then we have no idea when the next chunk of data will arrive.
            
            NSUInteger done = currentRead->bytesDone;
            NSUInteger total = currentRead->readLength;
            
            if (tagPtr != NULL)   *tagPtr = currentRead->tag;
            if (donePtr != NULL)  *donePtr = done;
            if (totalPtr != NULL) *totalPtr = total;
            
            if (total > 0)
                result = (float)done / (float)total;
            else
                result = 1.0F;
        }
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

/**
 * This method starts a new read, if needed.
 * 
 * It is called when:
 * - a user requests a read
 * - after a read request has finished (to handle the next request)
 * - immediately after the socket opens to handle any pending requests
 * 
 * This method also handles auto-disconnect post read/write completion.
**/
- (void)maybeDequeueRead
{
    LogTrace();
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    // If we're not currently processing a read AND we have an available read stream
    if ((currentRead == nil) && (flags & kConnected))
    {
        if ([readQueue count] > 0)
        {
            // Dequeue the next object in the write queue
            currentRead = [readQueue objectAtIndex:0];
            [readQueue removeObjectAtIndex:0];
            
            
            if ([currentRead isKindOfClass:[GCDAsyncSpecialPacket class]])
            {
                LogVerbose(@"Dequeued GCDAsyncSpecialPacket");
                
                // Attempt to start TLS
                flags |= kStartingReadTLS;
                
                // This method won't do anything unless both kStartingReadTLS and kStartingWriteTLS are set
                [self maybeStartTLS];
            }
            else
            {
                LogVerbose(@"Dequeued GCDAsyncReadPacket");
                
                // Setup read timer (if needed)
                [self setupReadTimerWithTimeout:currentRead->timeout];
                
                // Immediately read, if possible
                [self doReadData];
            }
        }
        else if (flags & kDisconnectAfterReads)
        {
            if (flags & kDisconnectAfterWrites)
            {
                if (([writeQueue count] == 0) && (currentWrite == nil))
                {
                    [self closeWithError:nil];
                }
            }
            else
            {
                [self closeWithError:nil];
            }
        }
        else if (flags & kSocketSecure)
        {
            [self flushSSLBuffers];
            
            // Edge case:
            // 
            // We just drained all data from the ssl buffers,
            // and all known data from the socket (socketFDBytesAvailable).
            // 
            // If we didn't get any data from this process,
            // then we may have reached the end of the TCP stream.
            // 
            // Be sure callbacks are enabled so we're notified about a disconnection.
            
            if ([preBuffer availableBytes] == 0)
            {
                if ([self usingCFStreamForTLS]) {
                    // Callbacks never disabled
                }
                else {
                    [self resumeReadSource];
                }
            }
        }
    }
}

- (void)flushSSLBuffers
{
    LogTrace();
    
    NSAssert((flags & kSocketSecure), @"Cannot flush ssl buffers on non-secure socket");
    
    if ([preBuffer availableBytes] > 0)
    {
        // Only flush the ssl buffers if the prebuffer is empty.
        // This is to avoid growing the prebuffer inifinitely large.
        
        return;
    }
    
#if TARGET_OS_IPHONE
    
    if ([self usingCFStreamForTLS])
    {
        if ((flags & kSecureSocketHasBytesAvailable) && CFReadStreamHasBytesAvailable(readStream))
        {
            LogVerbose(@"%@ - Flushing ssl buffers into prebuffer...", THIS_METHOD);
            
            CFIndex defaultBytesToRead = (1024 * 4);
            
            [preBuffer ensureCapacityForWrite:defaultBytesToRead];
            
            uint8_t *buffer = [preBuffer writeBuffer];
            
            CFIndex result = CFReadStreamRead(readStream, buffer, defaultBytesToRead);
            LogVerbose(@"%@ - CFReadStreamRead(): result = %i", THIS_METHOD, (int)result);
            
            if (result > 0)
            {
                [preBuffer didWrite:result];
            }
            
            flags &= ~kSecureSocketHasBytesAvailable;
        }
        
        return;
    }
    
#endif
#if SECURE_TRANSPORT_MAYBE_AVAILABLE
    
    __block NSUInteger estimatedBytesAvailable = 0;
    
    dispatch_block_t updateEstimatedBytesAvailable = ^{
        
        // Figure out if there is any data available to be read
        // 
        // socketFDBytesAvailable        <- Number of encrypted bytes we haven't read from the bsd socket
        // [sslPreBuffer availableBytes] <- Number of encrypted bytes we've buffered from bsd socket
        // sslInternalBufSize            <- Number of decrypted bytes SecureTransport has buffered
        // 
        // We call the variable "estimated" because we don't know how many decrypted bytes we'll get
        // from the encrypted bytes in the sslPreBuffer.
        // However, we do know this is an upper bound on the estimation.
        
        estimatedBytesAvailable = socketFDBytesAvailable + [sslPreBuffer availableBytes];
        
        size_t sslInternalBufSize = 0;
        SSLGetBufferedReadSize(sslContext, &sslInternalBufSize);
        
        estimatedBytesAvailable += sslInternalBufSize;
    };
    
    updateEstimatedBytesAvailable();
    
    if (estimatedBytesAvailable > 0)
    {
        LogVerbose(@"%@ - Flushing ssl buffers into prebuffer...", THIS_METHOD);
        
        BOOL done = NO;
        do
        {
            LogVerbose(@"%@ - estimatedBytesAvailable = %lu", THIS_METHOD, (unsigned long)estimatedBytesAvailable);
            
            // Make sure there's enough room in the prebuffer
            
            [preBuffer ensureCapacityForWrite:estimatedBytesAvailable];
            
            // Read data into prebuffer
            
            uint8_t *buffer = [preBuffer writeBuffer];
            size_t bytesRead = 0;
            
            OSStatus result = SSLRead(sslContext, buffer, (size_t)estimatedBytesAvailable, &bytesRead);
            LogVerbose(@"%@ - read from secure socket = %u", THIS_METHOD, (unsigned)bytesRead);
            
            if (bytesRead > 0)
            {
                [preBuffer didWrite:bytesRead];
            }
            
            LogVerbose(@"%@ - prebuffer.length = %zu", THIS_METHOD, [preBuffer availableBytes]);
            
            if (result != noErr)
            {
                done = YES;
            }
            else
            {
                updateEstimatedBytesAvailable();
            }
            
        } while (!done && estimatedBytesAvailable > 0);
    }
    
#endif
}

- (void)doReadData
{
    LogTrace();
    
    // This method is called on the socketQueue.
    // It might be called directly, or via the readSource when data is available to be read.
    
    if ((currentRead == nil) || (flags & kReadsPaused))
    {
        LogVerbose(@"No currentRead or kReadsPaused");
        
        // Unable to read at this time
        
        if (flags & kSocketSecure)
        {
            // Here's the situation:
            // 
            // We have an established secure connection.
            // There may not be a currentRead, but there might be encrypted data sitting around for us.
            // When the user does get around to issuing a read, that encrypted data will need to be decrypted.
            // 
            // So why make the user wait?
            // We might as well get a head start on decrypting some data now.
            // 
            // The other reason we do this has to do with detecting a socket disconnection.
            // The SSL/TLS protocol has it's own disconnection handshake.
            // So when a secure socket is closed, a "goodbye" packet comes across the wire.
            // We want to make sure we read the "goodbye" packet so we can properly detect the TCP disconnection.
            
            [self flushSSLBuffers];
        }
        
        if ([self usingCFStreamForTLS])
        {
            // CFReadStream only fires once when there is available data.
            // It won't fire again until we've invoked CFReadStreamRead.
        }
        else
        {
            // If the readSource is firing, we need to pause it
            // or else it will continue to fire over and over again.
            // 
            // If the readSource is not firing,
            // we want it to continue monitoring the socket.
            
            if (socketFDBytesAvailable > 0)
            {
                [self suspendReadSource];
            }
        }
        return;
    }
    
    BOOL hasBytesAvailable = NO;
    unsigned long estimatedBytesAvailable = 0;
    
    if ([self usingCFStreamForTLS])
    {
        #if TARGET_OS_IPHONE
        
        // Relegated to using CFStream... :( Boo! Give us a full SecureTransport stack Apple!
        
        estimatedBytesAvailable = 0;
        if ((flags & kSecureSocketHasBytesAvailable) && CFReadStreamHasBytesAvailable(readStream))
            hasBytesAvailable = YES;
        else
            hasBytesAvailable = NO;
        
        #endif
    }
    else
    {
        #if SECURE_TRANSPORT_MAYBE_AVAILABLE
        
        estimatedBytesAvailable = socketFDBytesAvailable;
        
        if (flags & kSocketSecure)
        {
            // There are 2 buffers to be aware of here.
            // 
            // We are using SecureTransport, a TLS/SSL security layer which sits atop TCP.
            // We issue a read to the SecureTranport API, which in turn issues a read to our SSLReadFunction.
            // Our SSLReadFunction then reads from the BSD socket and returns the encrypted data to SecureTransport.
            // SecureTransport then decrypts the data, and finally returns the decrypted data back to us.
            // 
            // The first buffer is one we create.
            // SecureTransport often requests small amounts of data.
            // This has to do with the encypted packets that are coming across the TCP stream.
            // But it's non-optimal to do a bunch of small reads from the BSD socket.
            // So our SSLReadFunction reads all available data from the socket (optimizing the sys call)
            // and may store excess in the sslPreBuffer.
            
            estimatedBytesAvailable += [sslPreBuffer availableBytes];
            
            // The second buffer is within SecureTransport.
            // As mentioned earlier, there are encrypted packets coming across the TCP stream.
            // SecureTransport needs the entire packet to decrypt it.
            // But if the entire packet produces X bytes of decrypted data,
            // and we only asked SecureTransport for X/2 bytes of data,
            // it must store the extra X/2 bytes of decrypted data for the next read.
            // 
            // The SSLGetBufferedReadSize function will tell us the size of this internal buffer.
            // From the documentation:
            // 
            // "This function does not block or cause any low-level read operations to occur."
            
            size_t sslInternalBufSize = 0;
            SSLGetBufferedReadSize(sslContext, &sslInternalBufSize);
            
            estimatedBytesAvailable += sslInternalBufSize;
        }
        
        hasBytesAvailable = (estimatedBytesAvailable > 0);
        
        #endif
    }
    
    if ((hasBytesAvailable == NO) && ([preBuffer availableBytes] == 0))
    {
        LogVerbose(@"No data available to read...");
        
        // No data available to read.
        
        if (![self usingCFStreamForTLS])
        {
            // Need to wait for readSource to fire and notify us of
            // available data in the socket's internal read buffer.
            
            [self resumeReadSource];
        }
        return;
    }
    
    if (flags & kStartingReadTLS)
    {
        LogVerbose(@"Waiting for SSL/TLS handshake to complete");
        
        // The readQueue is waiting for SSL/TLS handshake to complete.
        
        if (flags & kStartingWriteTLS)
        {
            if ([self usingSecureTransportForTLS])
            {
                #if SECURE_TRANSPORT_MAYBE_AVAILABLE
            
                // We are in the process of a SSL Handshake.
                // We were waiting for incoming data which has just arrived.
                
                [self ssl_continueSSLHandshake];
            
                #endif
            }
        }
        else
        {
            // We are still waiting for the writeQueue to drain and start the SSL/TLS process.
            // We now know data is available to read.
            
            if (![self usingCFStreamForTLS])
            {
                // Suspend the read source or else it will continue to fire nonstop.
                
                [self suspendReadSource];
            }
        }
        
        return;
    }
    
    BOOL done        = NO;  // Completed read operation
    NSError *error   = nil; // Error occured
    
    NSUInteger totalBytesReadForCurrentRead = 0;
    
    // 
    // STEP 1 - READ FROM PREBUFFER
    // 
    
    if ([preBuffer availableBytes] > 0)
    {
        // There are 3 types of read packets:
        // 
        // 1) Read all available data.
        // 2) Read a specific length of data.
        // 3) Read up to a particular terminator.
        
        NSUInteger bytesToCopy;
        
        if (currentRead->term != nil)
        {
            // Read type #3 - read up to a terminator
            
            bytesToCopy = [currentRead readLengthForTermWithPreBuffer:preBuffer found:&done];
        }
        else
        {
            // Read type #1 or #2
            
            bytesToCopy = [currentRead readLengthForNonTermWithHint:[preBuffer availableBytes]];
        }
        
        // Make sure we have enough room in the buffer for our read.
        
        [currentRead ensureCapacityForAdditionalDataOfLength:bytesToCopy];
        
        // Copy bytes from prebuffer into packet buffer
        
        uint8_t *buffer = (uint8_t *)[currentRead->buffer mutableBytes] + currentRead->startOffset +
                                                                          currentRead->bytesDone;
        
        memcpy(buffer, [preBuffer readBuffer], bytesToCopy);
        
        // Remove the copied bytes from the preBuffer
        [preBuffer didRead:bytesToCopy];
        
        LogVerbose(@"copied(%lu) preBufferLength(%zu)", (unsigned long)bytesToCopy, [preBuffer availableBytes]);
        
        // Update totals
        
        currentRead->bytesDone += bytesToCopy;
        totalBytesReadForCurrentRead += bytesToCopy;
        
        // Check to see if the read operation is done
        
        if (currentRead->readLength > 0)
        {
            // Read type #2 - read a specific length of data
            
            done = (currentRead->bytesDone == currentRead->readLength);
        }
        else if (currentRead->term != nil)
        {
            // Read type #3 - read up to a terminator
            
            // Our 'done' variable was updated via the readLengthForTermWithPreBuffer:found: method
            
            if (!done && currentRead->maxLength > 0)
            {
                // We're not done and there's a set maxLength.
                // Have we reached that maxLength yet?
                
                if (currentRead->bytesDone >= currentRead->maxLength)
                {
                    error = [self readMaxedOutError];
                }
            }
        }
        else
        {
            // Read type #1 - read all available data
            // 
            // We're done as soon as
            // - we've read all available data (in prebuffer and socket)
            // - we've read the maxLength of read packet.
            
            done = ((currentRead->maxLength > 0) && (currentRead->bytesDone == currentRead->maxLength));
        }
        
    }
    
    // 
    // STEP 2 - READ FROM SOCKET
    // 
    
    BOOL socketEOF = (flags & kSocketHasReadEOF) ? YES : NO;  // Nothing more to via socket (end of file)
    BOOL waiting   = !done && !error && !socketEOF && !hasBytesAvailable; // Ran out of data, waiting for more
    
    if (!done && !error && !socketEOF && !waiting && hasBytesAvailable)
    {
        NSAssert(([preBuffer availableBytes] == 0), @"Invalid logic");
        
        // There are 3 types of read packets:
        // 
        // 1) Read all available data.
        // 2) Read a specific length of data.
        // 3) Read up to a particular terminator.
        
        BOOL readIntoPreBuffer = NO;
        NSUInteger bytesToRead;
        
        if ([self usingCFStreamForTLS])
        {
            // Since Apple hasn't made the full power of SecureTransport available on iOS,
            // we are relegated to using the slower, less powerful, RunLoop based CFStream API.
            // 
            // This API doesn't tell us how much data is available on the socket to be read.
            // If we had that information we could optimize our memory allocations, and sys calls.
            // 
            // But alas...
            // So we do it old school, and just read as much data from the socket as we can.
            
            NSUInteger defaultReadLength = (1024 * 32);
            
            bytesToRead = [currentRead optimalReadLengthWithDefault:defaultReadLength
                                                    shouldPreBuffer:&readIntoPreBuffer];
        }
        else
        {
            if (currentRead->term != nil)
            {
                // Read type #3 - read up to a terminator
                
                bytesToRead = [currentRead readLengthForTermWithHint:estimatedBytesAvailable
                                                     shouldPreBuffer:&readIntoPreBuffer];
            }
            else
            {
                // Read type #1 or #2
                
                bytesToRead = [currentRead readLengthForNonTermWithHint:estimatedBytesAvailable];
            }
        }
        
        if (bytesToRead > SIZE_MAX) // NSUInteger may be bigger than size_t (read param 3)
        {
            bytesToRead = SIZE_MAX;
        }
        
        // Make sure we have enough room in the buffer for our read.
        // 
        // We are either reading directly into the currentRead->buffer,
        // or we're reading into the temporary preBuffer.
        
        uint8_t *buffer;
        
        if (readIntoPreBuffer)
        {
            [preBuffer ensureCapacityForWrite:bytesToRead];
                        
            buffer = [preBuffer writeBuffer];
        }
        else
        {
            [currentRead ensureCapacityForAdditionalDataOfLength:bytesToRead];
            
            buffer = (uint8_t *)[currentRead->buffer mutableBytes] + currentRead->startOffset + currentRead->bytesDone;
        }
        
        // Read data into buffer
        
        size_t bytesRead = 0;
        
        if (flags & kSocketSecure)
        {
            if ([self usingCFStreamForTLS])
            {
                #if TARGET_OS_IPHONE
                
                CFIndex result = CFReadStreamRead(readStream, buffer, (CFIndex)bytesToRead);
                LogVerbose(@"CFReadStreamRead(): result = %i", (int)result);
                
                if (result < 0)
                {
                    error = (__bridge_transfer NSError *)CFReadStreamCopyError(readStream);
                }
                else if (result == 0)
                {
                    socketEOF = YES;
                }
                else
                {
                    waiting = YES;
                    bytesRead = (size_t)result;
                }
                
                // We only know how many decrypted bytes were read.
                // The actual number of bytes read was likely more due to the overhead of the encryption.
                // So we reset our flag, and rely on the next callback to alert us of more data.
                flags &= ~kSecureSocketHasBytesAvailable;
                
                #endif
            }
            else
            {
                #if SECURE_TRANSPORT_MAYBE_AVAILABLE
                    
                // The documentation from Apple states:
                // 
                //     "a read operation might return errSSLWouldBlock,
                //      indicating that less data than requested was actually transferred"
                // 
                // However, starting around 10.7, the function will sometimes return noErr,
                // even if it didn't read as much data as requested. So we need to watch out for that.
                
                OSStatus result;
                do
                {
                    void *loop_buffer = buffer + bytesRead;
                    size_t loop_bytesToRead = (size_t)bytesToRead - bytesRead;
                    size_t loop_bytesRead = 0;
                    
                    result = SSLRead(sslContext, loop_buffer, loop_bytesToRead, &loop_bytesRead);
                    LogVerbose(@"read from secure socket = %u", (unsigned)bytesRead);
                    
                    bytesRead += loop_bytesRead;
                    
                } while ((result == noErr) && (bytesRead < bytesToRead));
                
                
                if (result != noErr)
                {
                    if (result == errSSLWouldBlock)
                        waiting = YES;
                    else
                    {
                        if (result == errSSLClosedGraceful || result == errSSLClosedAbort)
                        {
                            // We've reached the end of the stream.
                            // Handle this the same way we would an EOF from the socket.
                            socketEOF = YES;
                            sslErrCode = result;
                        }
                        else
                        {
                            error = [self sslError:result];
                        }
                    }
                    // It's possible that bytesRead > 0, even if the result was errSSLWouldBlock.
                    // This happens when the SSLRead function is able to read some data,
                    // but not the entire amount we requested.
                    
                    if (bytesRead <= 0)
                    {
                        bytesRead = 0;
                    }
                }
                
                // Do not modify socketFDBytesAvailable.
                // It will be updated via the SSLReadFunction().
                
                #endif
            }
        }
        else
        {
            int socketFD = (socket4FD == SOCKET_NULL) ? socket6FD : socket4FD;
            
            ssize_t result = read(socketFD, buffer, (size_t)bytesToRead);
            LogVerbose(@"read from socket = %i", (int)result);
            
            if (result < 0)
            {
                if (errno == EWOULDBLOCK)
                    waiting = YES;
                else
                    error = [self errnoErrorWithReason:@"Error in read() function"];
                
                socketFDBytesAvailable = 0;
            }
            else if (result == 0)
            {
                socketEOF = YES;
                socketFDBytesAvailable = 0;
            }
            else
            {
                bytesRead = result;
                
                if (bytesRead < bytesToRead)
                {
                    // The read returned less data than requested.
                    // This means socketFDBytesAvailable was a bit off due to timing,
                    // because we read from the socket right when the readSource event was firing.
                    socketFDBytesAvailable = 0;
                }
                else
                {
                    if (socketFDBytesAvailable <= bytesRead)
                        socketFDBytesAvailable = 0;
                    else
                        socketFDBytesAvailable -= bytesRead;
                }
                
                if (socketFDBytesAvailable == 0)
                {
                    waiting = YES;
                }
            }
        }
        
        if (bytesRead > 0)
        {
            // Check to see if the read operation is done
            
            if (currentRead->readLength > 0)
            {
                // Read type #2 - read a specific length of data
                // 
                // Note: We should never be using a prebuffer when we're reading a specific length of data.
                
                NSAssert(readIntoPreBuffer == NO, @"Invalid logic");
                
                currentRead->bytesDone += bytesRead;
                totalBytesReadForCurrentRead += bytesRead;
                
                done = (currentRead->bytesDone == currentRead->readLength);
            }
            else if (currentRead->term != nil)
            {
                // Read type #3 - read up to a terminator
                
                if (readIntoPreBuffer)
                {
                    // We just read a big chunk of data into the preBuffer
                    
                    [preBuffer didWrite:bytesRead];
                    LogVerbose(@"read data into preBuffer - preBuffer.length = %zu", [preBuffer availableBytes]);
                    
                    // Search for the terminating sequence
                    
                    bytesToRead = [currentRead readLengthForTermWithPreBuffer:preBuffer found:&done];
                    LogVerbose(@"copying %lu bytes from preBuffer", (unsigned long)bytesToRead);
                    
                    // Ensure there's room on the read packet's buffer
                    
                    [currentRead ensureCapacityForAdditionalDataOfLength:bytesToRead];
                    
                    // Copy bytes from prebuffer into read buffer
                    
                    uint8_t *readBuf = (uint8_t *)[currentRead->buffer mutableBytes] + currentRead->startOffset
                                                                                     + currentRead->bytesDone;
                    
                    memcpy(readBuf, [preBuffer readBuffer], bytesToRead);
                    
                    // Remove the copied bytes from the prebuffer
                    [preBuffer didRead:bytesToRead];
                    LogVerbose(@"preBuffer.length = %zu", [preBuffer availableBytes]);
                    
                    // Update totals
                    currentRead->bytesDone += bytesToRead;
                    totalBytesReadForCurrentRead += bytesToRead;
                    
                    // Our 'done' variable was updated via the readLengthForTermWithPreBuffer:found: method above
                }
                else
                {
                    // We just read a big chunk of data directly into the packet's buffer.
                    // We need to move any overflow into the prebuffer.
                    
                    NSInteger overflow = [currentRead searchForTermAfterPreBuffering:bytesRead];
                    
                    if (overflow == 0)
                    {
                        // Perfect match!
                        // Every byte we read stays in the read buffer,
                        // and the last byte we read was the last byte of the term.
                        
                        currentRead->bytesDone += bytesRead;
                        totalBytesReadForCurrentRead += bytesRead;
                        done = YES;
                    }
                    else if (overflow > 0)
                    {
                        // The term was found within the data that we read,
                        // and there are extra bytes that extend past the end of the term.
                        // We need to move these excess bytes out of the read packet and into the prebuffer.
                        
                        NSInteger underflow = bytesRead - overflow;
                        
                        // Copy excess data into preBuffer
                        
                        LogVerbose(@"copying %ld overflow bytes into preBuffer", (long)overflow);
                        [preBuffer ensureCapacityForWrite:overflow];
                        
                        uint8_t *overflowBuffer = buffer + underflow;
                        memcpy([preBuffer writeBuffer], overflowBuffer, overflow);
                        
                        [preBuffer didWrite:overflow];
                        LogVerbose(@"preBuffer.length = %zu", [preBuffer availableBytes]);
                        
                        // Note: The completeCurrentRead method will trim the buffer for us.
                        
                        currentRead->bytesDone += underflow;
                        totalBytesReadForCurrentRead += underflow;
                        done = YES;
                    }
                    else
                    {
                        // The term was not found within the data that we read.
                        
                        currentRead->bytesDone += bytesRead;
                        totalBytesReadForCurrentRead += bytesRead;
                        done = NO;
                    }
                }
                
                if (!done && currentRead->maxLength > 0)
                {
                    // We're not done and there's a set maxLength.
                    // Have we reached that maxLength yet?
                    
                    if (currentRead->bytesDone >= currentRead->maxLength)
                    {
                        error = [self readMaxedOutError];
                    }
                }
            }
            else
            {
                // Read type #1 - read all available data
                
                if (readIntoPreBuffer)
                {
                    // We just read a chunk of data into the preBuffer
                    
                    [preBuffer didWrite:bytesRead];
                    
                    // Now copy the data into the read packet.
                    // 
                    // Recall that we didn't read directly into the packet's buffer to avoid
                    // over-allocating memory since we had no clue how much data was available to be read.
                    // 
                    // Ensure there's room on the read packet's buffer
                    
                    [currentRead ensureCapacityForAdditionalDataOfLength:bytesRead];
                    
                    // Copy bytes from prebuffer into read buffer
                    
                    uint8_t *readBuf = (uint8_t *)[currentRead->buffer mutableBytes] + currentRead->startOffset
                                                                                     + currentRead->bytesDone;
                    
                    memcpy(readBuf, [preBuffer readBuffer], bytesRead);
                    
                    // Remove the copied bytes from the prebuffer
                    [preBuffer didRead:bytesRead];
                    
                    // Update totals
                    currentRead->bytesDone += bytesRead;
                    totalBytesReadForCurrentRead += bytesRead;
                }
                else
                {
                    currentRead->bytesDone += bytesRead;
                    totalBytesReadForCurrentRead += bytesRead;
                }
                
                done = YES;
            }
            
        } // if (bytesRead > 0)
        
    } // if (!done && !error && !socketEOF && !waiting && hasBytesAvailable)
    
    
    if (!done && currentRead->readLength == 0 && currentRead->term == nil)
    {
        // Read type #1 - read all available data
        // 
        // We might arrive here if we read data from the prebuffer but not from the socket.
        
        done = (totalBytesReadForCurrentRead > 0);
    }
    
    // Check to see if we're done, or if we've made progress
    
    if (done)
    {
        [self completeCurrentRead];
        
        if (!error && (!socketEOF || [preBuffer availableBytes] > 0))
        {
            [self maybeDequeueRead];
        }
    }
    else if (totalBytesReadForCurrentRead > 0)
    {
        // We're not done read type #2 or #3 yet, but we have read in some bytes
        
        if (delegateQueue && [delegate respondsToSelector:@selector(socket:didReadPartialDataOfLength:tag:)])
        {
            __strong id theDelegate = delegate;
            long theReadTag = currentRead->tag;
            
            dispatch_async(delegateQueue, ^{ @autoreleasepool {
                
                [theDelegate socket:self didReadPartialDataOfLength:totalBytesReadForCurrentRead tag:theReadTag];
            }});
        }
    }
    
    // Check for errors
    
    if (error)
    {
        [self closeWithError:error];
    }
    else if (socketEOF)
    {
        [self doReadEOF];
    }
    else if (waiting)
    {
        if (![self usingCFStreamForTLS])
        {
            // Monitor the socket for readability (if we're not already doing so)
            [self resumeReadSource];
        }
    }
    
    // Do not add any code here without first adding return statements in the error cases above.
}

- (void)doReadEOF
{
    LogTrace();
    
    // This method may be called more than once.
    // If the EOF is read while there is still data in the preBuffer,
    // then this method may be called continually after invocations of doReadData to see if it's time to disconnect.
    
    flags |= kSocketHasReadEOF;
    
    if (flags & kSocketSecure)
    {
        // If the SSL layer has any buffered data, flush it into the preBuffer now.
        
        [self flushSSLBuffers];
    }
    
    BOOL shouldDisconnect;
    NSError *error = nil;
    
    if ((flags & kStartingReadTLS) || (flags & kStartingWriteTLS))
    {
        // We received an EOF during or prior to startTLS.
        // The SSL/TLS handshake is now impossible, so this is an unrecoverable situation.
        
        shouldDisconnect = YES;
        
        if ([self usingSecureTransportForTLS])
        {
            #if SECURE_TRANSPORT_MAYBE_AVAILABLE
            error = [self sslError:errSSLClosedAbort];
            #endif
        }
    }
    else if (flags & kReadStreamClosed)
    {
        // The preBuffer has already been drained.
        // The config allows half-duplex connections.
        // We've previously checked the socket, and it appeared writeable.
        // So we marked the read stream as closed and notified the delegate.
        // 
        // As per the half-duplex contract, the socket will be closed when a write fails,
        // or when the socket is manually closed.
        
        shouldDisconnect = NO;
    }
    else if ([preBuffer availableBytes] > 0)
    {
        LogVerbose(@"Socket reached EOF, but there is still data available in prebuffer");
        
        // Although we won't be able to read any more data from the socket,
        // there is existing data that has been prebuffered that we can read.
        
        shouldDisconnect = NO;
    }
    else if (config & kAllowHalfDuplexConnection)
    {
        // We just received an EOF (end of file) from the socket's read stream.
        // This means the remote end of the socket (the peer we're connected to)
        // has explicitly stated that it will not be sending us any more data.
        // 
        // Query the socket to see if it is still writeable. (Perhaps the peer will continue reading data from us)
        
        int socketFD = (socket4FD == SOCKET_NULL) ? socket6FD : socket4FD;
        
        struct pollfd pfd[1];
        pfd[0].fd = socketFD;
        pfd[0].events = POLLOUT;
        pfd[0].revents = 0;
        
        poll(pfd, 1, 0);
        
        if (pfd[0].revents & POLLOUT)
        {
            // Socket appears to still be writeable
            
            shouldDisconnect = NO;
            flags |= kReadStreamClosed;
            
            // Notify the delegate that we're going half-duplex
            
            if (delegateQueue && [delegate respondsToSelector:@selector(socketDidCloseReadStream:)])
            {
                __strong id theDelegate = delegate;
                
                dispatch_async(delegateQueue, ^{ @autoreleasepool {
                    
                    [theDelegate socketDidCloseReadStream:self];
                }});
            }
        }
        else
        {
            shouldDisconnect = YES;
        }
    }
    else
    {
        shouldDisconnect = YES;
    }
    
    
    if (shouldDisconnect)
    {
        if (error == nil)
        {
            if ([self usingSecureTransportForTLS])
            {
                #if SECURE_TRANSPORT_MAYBE_AVAILABLE
                if (sslErrCode != noErr && sslErrCode != errSSLClosedGraceful)
                {
                    error = [self sslError:sslErrCode];
                }
                else
                {
                    error = [self connectionClosedError];
                }
                #endif
            }
            else
            {
                error = [self connectionClosedError];
            }
        }
        [self closeWithError:error];
    }
    else
    {
        if (![self usingCFStreamForTLS])
        {
            // Suspend the read source (if needed)
            
            [self suspendReadSource];
        }
    }
}

- (void)completeCurrentRead
{
    LogTrace();
    
    NSAssert(currentRead, @"Trying to complete current read when there is no current read.");
    
    
    NSData *result;
    
    if (currentRead->bufferOwner)
    {
        // We created the buffer on behalf of the user.
        // Trim our buffer to be the proper size.
        [currentRead->buffer setLength:currentRead->bytesDone];
        
        result = currentRead->buffer;
    }
    else
    {
        // We did NOT create the buffer.
        // The buffer is owned by the caller.
        // Only trim the buffer if we had to increase its size.
        
        if ([currentRead->buffer length] > currentRead->originalBufferLength)
        {
            NSUInteger readSize = currentRead->startOffset + currentRead->bytesDone;
            NSUInteger origSize = currentRead->originalBufferLength;
            
            NSUInteger buffSize = MAX(readSize, origSize);
            
            [currentRead->buffer setLength:buffSize];
        }
        
        uint8_t *buffer = (uint8_t *)[currentRead->buffer mutableBytes] + currentRead->startOffset;
        
        result = [NSData dataWithBytesNoCopy:buffer length:currentRead->bytesDone freeWhenDone:NO];
    }
    
    if (delegateQueue && [delegate respondsToSelector:@selector(socket:didReadData:withTag:)])
    {
        __strong id theDelegate = delegate;
        GCDAsyncReadPacket *theRead = currentRead; // Ensure currentRead retained since result may not own buffer
        
        dispatch_async(delegateQueue, ^{ @autoreleasepool {
            
            [theDelegate socket:self didReadData:result withTag:theRead->tag];
        }});
    }
    
    [self endCurrentRead];
}

- (void)endCurrentRead
{
    if (readTimer)
    {
        dispatch_source_cancel(readTimer);
        readTimer = NULL;
    }
    
    currentRead = nil;
}

- (void)setupReadTimerWithTimeout:(NSTimeInterval)timeout
{
    if (timeout >= 0.0)
    {
        readTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, socketQueue);
        
        dispatch_source_set_event_handler(readTimer, ^{ @autoreleasepool {
            
            [self doReadTimeout];
        }});
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        dispatch_source_t theReadTimer = readTimer;
        dispatch_source_set_cancel_handler(readTimer, ^{
            LogVerbose(@"dispatch_release(readTimer)");
            dispatch_release(theReadTimer);
        });
        #endif
        
        dispatch_time_t tt = dispatch_time(DISPATCH_TIME_NOW, (timeout * NSEC_PER_SEC));
        
        dispatch_source_set_timer(readTimer, tt, DISPATCH_TIME_FOREVER, 0);
        dispatch_resume(readTimer);
    }
}

- (void)doReadTimeout
{
    // This is a little bit tricky.
    // Ideally we'd like to synchronously query the delegate about a timeout extension.
    // But if we do so synchronously we risk a possible deadlock.
    // So instead we have to do so asynchronously, and callback to ourselves from within the delegate block.
    
    flags |= kReadsPaused;
    
    if (delegateQueue && [delegate respondsToSelector:@selector(socket:shouldTimeoutReadWithTag:elapsed:bytesDone:)])
    {
        __strong id theDelegate = delegate;
        GCDAsyncReadPacket *theRead = currentRead;
        
        dispatch_async(delegateQueue, ^{ @autoreleasepool {
            
            NSTimeInterval timeoutExtension = 0.0;
            
            timeoutExtension = [theDelegate socket:self shouldTimeoutReadWithTag:theRead->tag
                                                                         elapsed:theRead->timeout
                                                                       bytesDone:theRead->bytesDone];
            
            dispatch_async(socketQueue, ^{ @autoreleasepool {
                
                [self doReadTimeoutWithExtension:timeoutExtension];
            }});
        }});
    }
    else
    {
        [self doReadTimeoutWithExtension:0.0];
    }
}

- (void)doReadTimeoutWithExtension:(NSTimeInterval)timeoutExtension
{
    if (currentRead)
    {
        if (timeoutExtension > 0.0)
        {
            currentRead->timeout += timeoutExtension;
            
            // Reschedule the timer
            dispatch_time_t tt = dispatch_time(DISPATCH_TIME_NOW, (timeoutExtension * NSEC_PER_SEC));
            dispatch_source_set_timer(readTimer, tt, DISPATCH_TIME_FOREVER, 0);
            
            // Unpause reads, and continue
            flags &= ~kReadsPaused;
            [self doReadData];
        }
        else
        {
            LogVerbose(@"ReadTimeout");
            
            [self closeWithError:[self readTimeoutError]];
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Writing
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (void)writeData:(NSData *)data withTimeout:(NSTimeInterval)timeout tag:(long)tag
{
    if ([data length] == 0) return;
    
    GCDAsyncWritePacket *packet = [[GCDAsyncWritePacket alloc] initWithData:data timeout:timeout tag:tag];
    
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        LogTrace();
        
        if ((flags & kSocketStarted) && !(flags & kForbidReadsWrites))
        {
            [writeQueue addObject:packet];
            [self maybeDequeueWrite];
        }
    }});
    
    // Do not rely on the block being run in order to release the packet,
    // as the queue might get released without the block completing.
}

- (float)progressOfWriteReturningTag:(long *)tagPtr bytesDone:(NSUInteger *)donePtr total:(NSUInteger *)totalPtr
{
    __block float result = 0.0F;
    
    dispatch_block_t block = ^{
        
        if (!currentWrite || ![currentWrite isKindOfClass:[GCDAsyncWritePacket class]])
        {
            // We're not writing anything right now.
            
            if (tagPtr != NULL)   *tagPtr = 0;
            if (donePtr != NULL)  *donePtr = 0;
            if (totalPtr != NULL) *totalPtr = 0;
            
            result = NAN;
        }
        else
        {
            NSUInteger done = currentWrite->bytesDone;
            NSUInteger total = [currentWrite->buffer length];
            
            if (tagPtr != NULL)   *tagPtr = currentWrite->tag;
            if (donePtr != NULL)  *donePtr = done;
            if (totalPtr != NULL) *totalPtr = total;
            
            result = (float)done / (float)total;
        }
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
    
    return result;
}

/**
 * Conditionally starts a new write.
 * 
 * It is called when:
 * - a user requests a write
 * - after a write request has finished (to handle the next request)
 * - immediately after the socket opens to handle any pending requests
 * 
 * This method also handles auto-disconnect post read/write completion.
**/
- (void)maybeDequeueWrite
{
    LogTrace();
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    
    // If we're not currently processing a write AND we have an available write stream
    if ((currentWrite == nil) && (flags & kConnected))
    {
        if ([writeQueue count] > 0)
        {
            // Dequeue the next object in the write queue
            currentWrite = [writeQueue objectAtIndex:0];
            [writeQueue removeObjectAtIndex:0];
            
            
            if ([currentWrite isKindOfClass:[GCDAsyncSpecialPacket class]])
            {
                LogVerbose(@"Dequeued GCDAsyncSpecialPacket");
                
                // Attempt to start TLS
                flags |= kStartingWriteTLS;
                
                // This method won't do anything unless both kStartingReadTLS and kStartingWriteTLS are set
                [self maybeStartTLS];
            }
            else
            {
                LogVerbose(@"Dequeued GCDAsyncWritePacket");
                
                // Setup write timer (if needed)
                [self setupWriteTimerWithTimeout:currentWrite->timeout];
                
                // Immediately write, if possible
                [self doWriteData];
            }
        }
        else if (flags & kDisconnectAfterWrites)
        {
            if (flags & kDisconnectAfterReads)
            {
                if (([readQueue count] == 0) && (currentRead == nil))
                {
                    [self closeWithError:nil];
                }
            }
            else
            {
                [self closeWithError:nil];
            }
        }
    }
}

- (void)doWriteData
{
    LogTrace();
    
    // This method is called by the writeSource via the socketQueue
    
    if ((currentWrite == nil) || (flags & kWritesPaused))
    {
        LogVerbose(@"No currentWrite or kWritesPaused");
        
        // Unable to write at this time
        
        if ([self usingCFStreamForTLS])
        {
            // CFWriteStream only fires once when there is available data.
            // It won't fire again until we've invoked CFWriteStreamWrite.
        }
        else
        {
            // If the writeSource is firing, we need to pause it
            // or else it will continue to fire over and over again.
            
            if (flags & kSocketCanAcceptBytes)
            {
                [self suspendWriteSource];
            }
        }
        return;
    }
    
    if (!(flags & kSocketCanAcceptBytes))
    {
        LogVerbose(@"No space available to write...");
        
        // No space available to write.
        
        if (![self usingCFStreamForTLS])
        {
            // Need to wait for writeSource to fire and notify us of
            // available space in the socket's internal write buffer.
            
            [self resumeWriteSource];
        }
        return;
    }
    
    if (flags & kStartingWriteTLS)
    {
        LogVerbose(@"Waiting for SSL/TLS handshake to complete");
        
        // The writeQueue is waiting for SSL/TLS handshake to complete.
        
        if (flags & kStartingReadTLS)
        {
            if ([self usingSecureTransportForTLS])
            {
                #if SECURE_TRANSPORT_MAYBE_AVAILABLE
            
                // We are in the process of a SSL Handshake.
                // We were waiting for available space in the socket's internal OS buffer to continue writing.
            
                [self ssl_continueSSLHandshake];
            
                #endif
            }
        }
        else
        {
            // We are still waiting for the readQueue to drain and start the SSL/TLS process.
            // We now know we can write to the socket.
            
            if (![self usingCFStreamForTLS])
            {
                // Suspend the write source or else it will continue to fire nonstop.
                
                [self suspendWriteSource];
            }
        }
        
        return;
    }
    
    // Note: This method is not called if currentWrite is a GCDAsyncSpecialPacket (startTLS packet)
    
    BOOL waiting = NO;
    NSError *error = nil;
    size_t bytesWritten = 0;
    
    if (flags & kSocketSecure)
    {
        if ([self usingCFStreamForTLS])
        {
            #if TARGET_OS_IPHONE
            
            // 
            // Writing data using CFStream (over internal TLS)
            // 
            
            const uint8_t *buffer = (const uint8_t *)[currentWrite->buffer bytes] + currentWrite->bytesDone;
            
            NSUInteger bytesToWrite = [currentWrite->buffer length] - currentWrite->bytesDone;
            
            if (bytesToWrite > SIZE_MAX) // NSUInteger may be bigger than size_t (write param 3)
            {
                bytesToWrite = SIZE_MAX;
            }
        
            CFIndex result = CFWriteStreamWrite(writeStream, buffer, (CFIndex)bytesToWrite);
            LogVerbose(@"CFWriteStreamWrite(%lu) = %li", (unsigned long)bytesToWrite, result);
        
            if (result < 0)
            {
                error = (__bridge_transfer NSError *)CFWriteStreamCopyError(writeStream);
            }
            else
            {
                bytesWritten = (size_t)result;
                
                // We always set waiting to true in this scenario.
                // CFStream may have altered our underlying socket to non-blocking.
                // Thus if we attempt to write without a callback, we may end up blocking our queue.
                waiting = YES;
            }
            
            #endif
        }
        else
        {
            #if SECURE_TRANSPORT_MAYBE_AVAILABLE
            
            // We're going to use the SSLWrite function.
            // 
            // OSStatus SSLWrite(SSLContextRef context, const void *data, size_t dataLength, size_t *processed)
            // 
            // Parameters:
            // context     - An SSL session context reference.
            // data        - A pointer to the buffer of data to write.
            // dataLength  - The amount, in bytes, of data to write.
            // processed   - On return, the length, in bytes, of the data actually written.
            // 
            // It sounds pretty straight-forward,
            // but there are a few caveats you should be aware of.
            // 
            // The SSLWrite method operates in a non-obvious (and rather annoying) manner.
            // According to the documentation:
            // 
            //   Because you may configure the underlying connection to operate in a non-blocking manner,
            //   a write operation might return errSSLWouldBlock, indicating that less data than requested
            //   was actually transferred. In this case, you should repeat the call to SSLWrite until some
            //   other result is returned.
            // 
            // This sounds perfect, but when our SSLWriteFunction returns errSSLWouldBlock,
            // then the SSLWrite method returns (with the proper errSSLWouldBlock return value),
            // but it sets processed to dataLength !!
            // 
            // In other words, if the SSLWrite function doesn't completely write all the data we tell it to,
            // then it doesn't tell us how many bytes were actually written. So, for example, if we tell it to
            // write 256 bytes then it might actually write 128 bytes, but then report 0 bytes written.
            // 
            // You might be wondering:
            // If the SSLWrite function doesn't tell us how many bytes were written,
            // then how in the world are we supposed to update our parameters (buffer & bytesToWrite)
            // for the next time we invoke SSLWrite?
            // 
            // The answer is that SSLWrite cached all the data we told it to write,
            // and it will push out that data next time we call SSLWrite.
            // If we call SSLWrite with new data, it will push out the cached data first, and then the new data.
            // If we call SSLWrite with empty data, then it will simply push out the cached data.
            // 
            // For this purpose we're going to break large writes into a series of smaller writes.
            // This allows us to report progress back to the delegate.
            
            OSStatus result;
            
            BOOL hasCachedDataToWrite = (sslWriteCachedLength > 0);
            BOOL hasNewDataToWrite = YES;
            
            if (hasCachedDataToWrite)
            {
                size_t processed = 0;
                
                result = SSLWrite(sslContext, NULL, 0, &processed);
                
                if (result == noErr)
                {
                    bytesWritten = sslWriteCachedLength;
                    sslWriteCachedLength = 0;
                    
                    if ([currentWrite->buffer length] == (currentWrite->bytesDone + bytesWritten))
                    {
                        // We've written all data for the current write.
                        hasNewDataToWrite = NO;
                    }
                }
                else
                {
                    if (result == errSSLWouldBlock)
                    {
                        waiting = YES;
                    }
                    else
                    {
                        error = [self sslError:result];
                    }
                    
                    // Can't write any new data since we were unable to write the cached data.
                    hasNewDataToWrite = NO;
                }
            }
            
            if (hasNewDataToWrite)
            {
                const uint8_t *buffer = (const uint8_t *)[currentWrite->buffer bytes]
                                                        + currentWrite->bytesDone
                                                        + bytesWritten;
                
                NSUInteger bytesToWrite = [currentWrite->buffer length] - currentWrite->bytesDone - bytesWritten;
                
                if (bytesToWrite > SIZE_MAX) // NSUInteger may be bigger than size_t (write param 3)
                {
                    bytesToWrite = SIZE_MAX;
                }
                
                size_t bytesRemaining = bytesToWrite;
                
                BOOL keepLooping = YES;
                while (keepLooping)
                {
                    size_t sslBytesToWrite = MIN(bytesRemaining, 32768);
                    size_t sslBytesWritten = 0;
                    
                    result = SSLWrite(sslContext, buffer, sslBytesToWrite, &sslBytesWritten);
                    
                    if (result == noErr)
                    {
                        buffer += sslBytesWritten;
                        bytesWritten += sslBytesWritten;
                        bytesRemaining -= sslBytesWritten;
                        
                        keepLooping = (bytesRemaining > 0);
                    }
                    else
                    {
                        if (result == errSSLWouldBlock)
                        {
                            waiting = YES;
                            sslWriteCachedLength = sslBytesToWrite;
                        }
                        else
                        {
                            error = [self sslError:result];
                        }
                        
                        keepLooping = NO;
                    }
                    
                } // while (keepLooping)
                
            } // if (hasNewDataToWrite)
        
            #endif
        }
    }
    else
    {
        // 
        // Writing data directly over raw socket
        // 
        
        int socketFD = (socket4FD == SOCKET_NULL) ? socket6FD : socket4FD;
        
        const uint8_t *buffer = (const uint8_t *)[currentWrite->buffer bytes] + currentWrite->bytesDone;
        
        NSUInteger bytesToWrite = [currentWrite->buffer length] - currentWrite->bytesDone;
        
        if (bytesToWrite > SIZE_MAX) // NSUInteger may be bigger than size_t (write param 3)
        {
            bytesToWrite = SIZE_MAX;
        }
        
        ssize_t result = write(socketFD, buffer, (size_t)bytesToWrite);
        LogVerbose(@"wrote to socket = %zd", result);
        
        // Check results
        if (result < 0)
        {
            if (errno == EWOULDBLOCK)
            {
                waiting = YES;
            }
            else
            {
                error = [self errnoErrorWithReason:@"Error in write() function"];
            }
        }
        else
        {
            bytesWritten = result;
        }
    }
    
    // We're done with our writing.
    // If we explictly ran into a situation where the socket told us there was no room in the buffer,
    // then we immediately resume listening for notifications.
    // 
    // We must do this before we dequeue another write,
    // as that may in turn invoke this method again.
    // 
    // Note that if CFStream is involved, it may have maliciously put our socket in blocking mode.
    
    if (waiting)
    {
        flags &= ~kSocketCanAcceptBytes;
        
        if (![self usingCFStreamForTLS])
        {
            [self resumeWriteSource];
        }
    }
    
    // Check our results
    
    BOOL done = NO;
    
    if (bytesWritten > 0)
    {
        // Update total amount read for the current write
        currentWrite->bytesDone += bytesWritten;
        LogVerbose(@"currentWrite->bytesDone = %lu", (unsigned long)currentWrite->bytesDone);
        
        // Is packet done?
        done = (currentWrite->bytesDone == [currentWrite->buffer length]);
    }
    
    if (done)
    {
        [self completeCurrentWrite];
        
        if (!error)
        {
            [self maybeDequeueWrite];
        }
    }
    else
    {
        // We were unable to finish writing the data,
        // so we're waiting for another callback to notify us of available space in the lower-level output buffer.
        
        if (!waiting & !error)
        {
            // This would be the case if our write was able to accept some data, but not all of it.
            
            flags &= ~kSocketCanAcceptBytes;
            
            if (![self usingCFStreamForTLS])
            {
                [self resumeWriteSource];
            }
        }
        
        if (bytesWritten > 0)
        {
            // We're not done with the entire write, but we have written some bytes
            
            if (delegateQueue && [delegate respondsToSelector:@selector(socket:didWritePartialDataOfLength:tag:)])
            {
                __strong id theDelegate = delegate;
                long theWriteTag = currentWrite->tag;
                
                dispatch_async(delegateQueue, ^{ @autoreleasepool {
                    
                    [theDelegate socket:self didWritePartialDataOfLength:bytesWritten tag:theWriteTag];
                }});
            }
        }
    }
    
    // Check for errors
    
    if (error)
    {
        [self closeWithError:[self errnoErrorWithReason:@"Error in write() function"]];
    }
    
    // Do not add any code here without first adding a return statement in the error case above.
}

- (void)completeCurrentWrite
{
    LogTrace();
    
    NSAssert(currentWrite, @"Trying to complete current write when there is no current write.");
    
    
    if (delegateQueue && [delegate respondsToSelector:@selector(socket:didWriteDataWithTag:)])
    {
        __strong id theDelegate = delegate;
        long theWriteTag = currentWrite->tag;
        
        dispatch_async(delegateQueue, ^{ @autoreleasepool {
            
            [theDelegate socket:self didWriteDataWithTag:theWriteTag];
        }});
    }
    
    [self endCurrentWrite];
}

- (void)endCurrentWrite
{
    if (writeTimer)
    {
        dispatch_source_cancel(writeTimer);
        writeTimer = NULL;
    }
    
    currentWrite = nil;
}

- (void)setupWriteTimerWithTimeout:(NSTimeInterval)timeout
{
    if (timeout >= 0.0)
    {
        writeTimer = dispatch_source_create(DISPATCH_SOURCE_TYPE_TIMER, 0, 0, socketQueue);
        
        dispatch_source_set_event_handler(writeTimer, ^{ @autoreleasepool {
            
            [self doWriteTimeout];
        }});
        
        #if NEEDS_DISPATCH_RETAIN_RELEASE
        dispatch_source_t theWriteTimer = writeTimer;
        dispatch_source_set_cancel_handler(writeTimer, ^{
            LogVerbose(@"dispatch_release(writeTimer)");
            dispatch_release(theWriteTimer);
        });
        #endif
        
        dispatch_time_t tt = dispatch_time(DISPATCH_TIME_NOW, (timeout * NSEC_PER_SEC));
        
        dispatch_source_set_timer(writeTimer, tt, DISPATCH_TIME_FOREVER, 0);
        dispatch_resume(writeTimer);
    }
}

- (void)doWriteTimeout
{
    // This is a little bit tricky.
    // Ideally we'd like to synchronously query the delegate about a timeout extension.
    // But if we do so synchronously we risk a possible deadlock.
    // So instead we have to do so asynchronously, and callback to ourselves from within the delegate block.
    
    flags |= kWritesPaused;
    
    if (delegateQueue && [delegate respondsToSelector:@selector(socket:shouldTimeoutWriteWithTag:elapsed:bytesDone:)])
    {
        __strong id theDelegate = delegate;
        GCDAsyncWritePacket *theWrite = currentWrite;
        
        dispatch_async(delegateQueue, ^{ @autoreleasepool {
            
            NSTimeInterval timeoutExtension = 0.0;
            
            timeoutExtension = [theDelegate socket:self shouldTimeoutWriteWithTag:theWrite->tag
                                                                          elapsed:theWrite->timeout
                                                                        bytesDone:theWrite->bytesDone];
            
            dispatch_async(socketQueue, ^{ @autoreleasepool {
                
                [self doWriteTimeoutWithExtension:timeoutExtension];
            }});
        }});
    }
    else
    {
        [self doWriteTimeoutWithExtension:0.0];
    }
}

- (void)doWriteTimeoutWithExtension:(NSTimeInterval)timeoutExtension
{
    if (currentWrite)
    {
        if (timeoutExtension > 0.0)
        {
            currentWrite->timeout += timeoutExtension;
            
            // Reschedule the timer
            dispatch_time_t tt = dispatch_time(DISPATCH_TIME_NOW, (timeoutExtension * NSEC_PER_SEC));
            dispatch_source_set_timer(writeTimer, tt, DISPATCH_TIME_FOREVER, 0);
            
            // Unpause writes, and continue
            flags &= ~kWritesPaused;
            [self doWriteData];
        }
        else
        {
            LogVerbose(@"WriteTimeout");
            
            [self closeWithError:[self writeTimeoutError]];
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Security
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

- (void)startTLS:(NSDictionary *)tlsSettings
{
    LogTrace();
    
    if (tlsSettings == nil)
    {
        // Passing nil/NULL to CFReadStreamSetProperty will appear to work the same as passing an empty dictionary,
        // but causes problems if we later try to fetch the remote host's certificate.
        // 
        // To be exact, it causes the following to return NULL instead of the normal result:
        // CFReadStreamCopyProperty(readStream, kCFStreamPropertySSLPeerCertificates)
        // 
        // So we use an empty dictionary instead, which works perfectly.
        
        tlsSettings = [NSDictionary dictionary];
    }
    
    GCDAsyncSpecialPacket *packet = [[GCDAsyncSpecialPacket alloc] initWithTLSSettings:tlsSettings];
    
    dispatch_async(socketQueue, ^{ @autoreleasepool {
        
        if ((flags & kSocketStarted) && !(flags & kQueuedTLS) && !(flags & kForbidReadsWrites))
        {
            [readQueue addObject:packet];
            [writeQueue addObject:packet];
            
            flags |= kQueuedTLS;
            
            [self maybeDequeueRead];
            [self maybeDequeueWrite];
        }
    }});
    
}

- (void)maybeStartTLS
{
    // We can't start TLS until:
    // - All queued reads prior to the user calling startTLS are complete
    // - All queued writes prior to the user calling startTLS are complete
    // 
    // We'll know these conditions are met when both kStartingReadTLS and kStartingWriteTLS are set
    
    if ((flags & kStartingReadTLS) && (flags & kStartingWriteTLS))
    {
        BOOL canUseSecureTransport = YES;
        
        #if TARGET_OS_IPHONE
        {
            GCDAsyncSpecialPacket *tlsPacket = (GCDAsyncSpecialPacket *)currentRead;
            NSDictionary *tlsSettings = tlsPacket->tlsSettings;
            
            NSNumber *value;
            
            value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLAllowsAnyRoot];
            if (value && [value boolValue] == YES)
                canUseSecureTransport = NO;
            
            value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLAllowsExpiredRoots];
            if (value && [value boolValue] == YES)
                canUseSecureTransport = NO;
            
            value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLValidatesCertificateChain];
            if (value && [value boolValue] == NO)
                canUseSecureTransport = NO;
            
            value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLAllowsExpiredCertificates];
            if (value && [value boolValue] == YES)
                canUseSecureTransport = NO;
        }
        #endif
        
        if (IS_SECURE_TRANSPORT_AVAILABLE && canUseSecureTransport)
        {
        #if SECURE_TRANSPORT_MAYBE_AVAILABLE
            [self ssl_startTLS];
        #endif
        }
        else
        {
        #if TARGET_OS_IPHONE
            [self cf_startTLS];
        #endif
        }
    }
}

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Security via SecureTransport
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#if SECURE_TRANSPORT_MAYBE_AVAILABLE

- (OSStatus)sslReadWithBuffer:(void *)buffer length:(size_t *)bufferLength
{
    LogVerbose(@"sslReadWithBuffer:%p length:%lu", buffer, (unsigned long)*bufferLength);
    
    if ((socketFDBytesAvailable == 0) && ([sslPreBuffer availableBytes] == 0))
    {
        LogVerbose(@"%@ - No data available to read...", THIS_METHOD);
        
        // No data available to read.
        // 
        // Need to wait for readSource to fire and notify us of
        // available data in the socket's internal read buffer.
        
        [self resumeReadSource];
        
        *bufferLength = 0;
        return errSSLWouldBlock;
    }
    
    size_t totalBytesRead = 0;
    size_t totalBytesLeftToBeRead = *bufferLength;
    
    BOOL done = NO;
    BOOL socketError = NO;
    
    // 
    // STEP 1 : READ FROM SSL PRE BUFFER
    // 
    
    size_t sslPreBufferLength = [sslPreBuffer availableBytes];
    
    if (sslPreBufferLength > 0)
    {
        LogVerbose(@"%@: Reading from SSL pre buffer...", THIS_METHOD);
        
        size_t bytesToCopy;
        if (sslPreBufferLength > totalBytesLeftToBeRead)
            bytesToCopy = totalBytesLeftToBeRead;
        else
            bytesToCopy = sslPreBufferLength;
        
        LogVerbose(@"%@: Copying %zu bytes from sslPreBuffer", THIS_METHOD, bytesToCopy);
        
        memcpy(buffer, [sslPreBuffer readBuffer], bytesToCopy);
        [sslPreBuffer didRead:bytesToCopy];
        
        LogVerbose(@"%@: sslPreBuffer.length = %zu", THIS_METHOD, [sslPreBuffer availableBytes]);
        
        totalBytesRead += bytesToCopy;
        totalBytesLeftToBeRead -= bytesToCopy;
        
        done = (totalBytesLeftToBeRead == 0);
        
        if (done) LogVerbose(@"%@: Complete", THIS_METHOD);
    }
    
    // 
    // STEP 2 : READ FROM SOCKET
    // 
    
    if (!done && (socketFDBytesAvailable > 0))
    {
        LogVerbose(@"%@: Reading from socket...", THIS_METHOD);
        
        int socketFD = (socket6FD == SOCKET_NULL) ? socket4FD : socket6FD;
        
        BOOL readIntoPreBuffer;
        size_t bytesToRead;
        uint8_t *buf;
        
        if (socketFDBytesAvailable > totalBytesLeftToBeRead)
        {
            // Read all available data from socket into sslPreBuffer.
            // Then copy requested amount into dataBuffer.
            
            LogVerbose(@"%@: Reading into sslPreBuffer...", THIS_METHOD);
            
            [sslPreBuffer ensureCapacityForWrite:socketFDBytesAvailable];
            
            readIntoPreBuffer = YES;
            bytesToRead = (size_t)socketFDBytesAvailable;
            buf = [sslPreBuffer writeBuffer];
        }
        else
        {
            // Read available data from socket directly into dataBuffer.
            
            LogVerbose(@"%@: Reading directly into dataBuffer...", THIS_METHOD);
            
            readIntoPreBuffer = NO;
            bytesToRead = totalBytesLeftToBeRead;
            buf = (uint8_t *)buffer + totalBytesRead;
        }
        
        ssize_t result = read(socketFD, buf, bytesToRead);
        LogVerbose(@"%@: read from socket = %zd", THIS_METHOD, result);
        
        if (result < 0)
        {
            LogVerbose(@"%@: read errno = %i", THIS_METHOD, errno);
            
            if (errno != EWOULDBLOCK)
            {
                socketError = YES;
            }
            
            socketFDBytesAvailable = 0;
        }
        else if (result == 0)
        {
            LogVerbose(@"%@: read EOF", THIS_METHOD);
            
            socketError = YES;
            socketFDBytesAvailable = 0;
        }
        else
        {
            size_t bytesReadFromSocket = result;
            
            if (socketFDBytesAvailable > bytesReadFromSocket)
                socketFDBytesAvailable -= bytesReadFromSocket;
            else
                socketFDBytesAvailable = 0;
            
            if (readIntoPreBuffer)
            {
                [sslPreBuffer didWrite:bytesReadFromSocket];
                
                size_t bytesToCopy = MIN(totalBytesLeftToBeRead, bytesReadFromSocket);
                
                LogVerbose(@"%@: Copying %zu bytes out of sslPreBuffer", THIS_METHOD, bytesToCopy);
                
                memcpy((uint8_t *)buffer + totalBytesRead, [sslPreBuffer readBuffer], bytesToCopy);
                [sslPreBuffer didRead:bytesToCopy];
                
                totalBytesRead += bytesToCopy;
                totalBytesLeftToBeRead -= bytesToCopy;
                
                LogVerbose(@"%@: sslPreBuffer.length = %zu", THIS_METHOD, [sslPreBuffer availableBytes]);
            }
            else
            {
                totalBytesRead += bytesReadFromSocket;
                totalBytesLeftToBeRead -= bytesReadFromSocket;
            }
            
            done = (totalBytesLeftToBeRead == 0);
            
            if (done) LogVerbose(@"%@: Complete", THIS_METHOD);
        }
    }
    
    *bufferLength = totalBytesRead;
    
    if (done)
        return noErr;
    
    if (socketError)
        return errSSLClosedAbort;
    
    return errSSLWouldBlock;
}

- (OSStatus)sslWriteWithBuffer:(const void *)buffer length:(size_t *)bufferLength
{
    if (!(flags & kSocketCanAcceptBytes))
    {
        // Unable to write.
        // 
        // Need to wait for writeSource to fire and notify us of
        // available space in the socket's internal write buffer.
        
        [self resumeWriteSource];
        
        *bufferLength = 0;
        return errSSLWouldBlock;
    }
    
    size_t bytesToWrite = *bufferLength;
    size_t bytesWritten = 0;
    
    BOOL done = NO;
    BOOL socketError = NO;
    
    int socketFD = (socket4FD == SOCKET_NULL) ? socket6FD : socket4FD;
    
    ssize_t result = write(socketFD, buffer, bytesToWrite);
    
    if (result < 0)
    {
        if (errno != EWOULDBLOCK)
        {
            socketError = YES;
        }
        
        flags &= ~kSocketCanAcceptBytes;
    }
    else if (result == 0)
    {
        flags &= ~kSocketCanAcceptBytes;
    }
    else
    {
        bytesWritten = result;
        
        done = (bytesWritten == bytesToWrite);
    }
    
    *bufferLength = bytesWritten;
    
    if (done)
        return noErr;
    
    if (socketError)
        return errSSLClosedAbort;
    
    return errSSLWouldBlock;
}

static OSStatus SSLReadFunction(SSLConnectionRef connection, void *data, size_t *dataLength)
{
    GCDAsyncSocket *asyncSocket = (__bridge GCDAsyncSocket *)connection;
    
    NSCAssert(dispatch_get_specific(asyncSocket->IsOnSocketQueueOrTargetQueueKey), @"What the deuce?");
    
    return [asyncSocket sslReadWithBuffer:data length:dataLength];
}

static OSStatus SSLWriteFunction(SSLConnectionRef connection, const void *data, size_t *dataLength)
{
    GCDAsyncSocket *asyncSocket = (__bridge GCDAsyncSocket *)connection;
    
    NSCAssert(dispatch_get_specific(asyncSocket->IsOnSocketQueueOrTargetQueueKey), @"What the deuce?");
    
    return [asyncSocket sslWriteWithBuffer:data length:dataLength];
}

- (void)ssl_startTLS
{
    LogTrace();
    
    LogVerbose(@"Starting TLS (via SecureTransport)...");
        
    OSStatus status;
    
    GCDAsyncSpecialPacket *tlsPacket = (GCDAsyncSpecialPacket *)currentRead;
    NSDictionary *tlsSettings = tlsPacket->tlsSettings;
    
    // Create SSLContext, and setup IO callbacks and connection ref
    
    BOOL isServer = [[tlsSettings objectForKey:(NSString *)kCFStreamSSLIsServer] boolValue];
    
    #if TARGET_OS_IPHONE
    {
        if (isServer)
            sslContext = SSLCreateContext(kCFAllocatorDefault, kSSLServerSide, kSSLStreamType);
        else
            sslContext = SSLCreateContext(kCFAllocatorDefault, kSSLClientSide, kSSLStreamType);
        
        if (sslContext == NULL)
        {
            [self closeWithError:[self otherError:@"Error in SSLCreateContext"]];
            return;
        }
    }
    #else
    {
        status = SSLNewContext(isServer, &sslContext);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLNewContext"]];
            return;
        }
    }
    #endif
    
    status = SSLSetIOFuncs(sslContext, &SSLReadFunction, &SSLWriteFunction);
    if (status != noErr)
    {
        [self closeWithError:[self otherError:@"Error in SSLSetIOFuncs"]];
        return;
    }
    
    status = SSLSetConnection(sslContext, (__bridge SSLConnectionRef)self);
    if (status != noErr)
    {
        [self closeWithError:[self otherError:@"Error in SSLSetConnection"]];
        return;
    }
    
    // Configure SSLContext from given settings
    // 
    // Checklist:
    // 1. kCFStreamSSLPeerName
    // 2. kCFStreamSSLAllowsAnyRoot
    // 3. kCFStreamSSLAllowsExpiredRoots
    // 4. kCFStreamSSLValidatesCertificateChain
    // 5. kCFStreamSSLAllowsExpiredCertificates
    // 6. kCFStreamSSLCertificates
    // 7. kCFStreamSSLLevel (GCDAsyncSocketSSLProtocolVersionMin / GCDAsyncSocketSSLProtocolVersionMax)
    // 8. GCDAsyncSocketSSLCipherSuites
    // 9. GCDAsyncSocketSSLDiffieHellmanParameters (Mac)
    
    id value;
    
    // 1. kCFStreamSSLPeerName
    
    value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLPeerName];
    if ([value isKindOfClass:[NSString class]])
    {
        NSString *peerName = (NSString *)value;
        
        const char *peer = [peerName UTF8String];
        size_t peerLen = strlen(peer);
        
        status = SSLSetPeerDomainName(sslContext, peer, peerLen);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetPeerDomainName"]];
            return;
        }
    }
    
    // 2. kCFStreamSSLAllowsAnyRoot
    
    value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLAllowsAnyRoot];
    if (value)
    {
        #if TARGET_OS_IPHONE
        NSAssert(NO, @"Security option unavailable via SecureTransport in iOS - kCFStreamSSLAllowsAnyRoot");
        #else
        
        BOOL allowsAnyRoot = [value boolValue];
        
        status = SSLSetAllowsAnyRoot(sslContext, allowsAnyRoot);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetAllowsAnyRoot"]];
            return;
        }
        
        #endif
    }
    
    // 3. kCFStreamSSLAllowsExpiredRoots
    
    value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLAllowsExpiredRoots];
    if (value)
    {
        #if TARGET_OS_IPHONE
        NSAssert(NO, @"Security option unavailable via SecureTransport in iOS - kCFStreamSSLAllowsExpiredRoots");
        #else
        
        BOOL allowsExpiredRoots = [value boolValue];
        
        status = SSLSetAllowsExpiredRoots(sslContext, allowsExpiredRoots);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetAllowsExpiredRoots"]];
            return;
        }
        
        #endif
    }
    
    // 4. kCFStreamSSLValidatesCertificateChain
    
    value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLValidatesCertificateChain];
    if (value)
    {
        #if TARGET_OS_IPHONE
        NSAssert(NO, @"Security option unavailable via SecureTransport in iOS - kCFStreamSSLValidatesCertificateChain");
        #else
        
        BOOL validatesCertChain = [value boolValue];
        
        status = SSLSetEnableCertVerify(sslContext, validatesCertChain);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetEnableCertVerify"]];
            return;
        }
        
        #endif
    }
    
    // 5. kCFStreamSSLAllowsExpiredCertificates
    
    value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLAllowsExpiredCertificates];
    if (value)
    {
        #if TARGET_OS_IPHONE
        NSAssert(NO, @"Security option unavailable via SecureTransport in iOS - kCFStreamSSLAllowsExpiredCertificates");
        #else
        
        BOOL allowsExpiredCerts = [value boolValue];
        
        status = SSLSetAllowsExpiredCerts(sslContext, allowsExpiredCerts);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetAllowsExpiredCerts"]];
            return;
        }
        
        #endif
    }
    
    // 6. kCFStreamSSLCertificates
    
    value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLCertificates];
    if (value)
    {
        CFArrayRef certs = (__bridge CFArrayRef)value;
        
        status = SSLSetCertificate(sslContext, certs);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetCertificate"]];
            return;
        }
    }
    
    // 7. kCFStreamSSLLevel
    
    #if TARGET_OS_IPHONE
    {
        NSString *sslLevel = [tlsSettings objectForKey:(NSString *)kCFStreamSSLLevel];
        
        NSString *sslMinLevel = [tlsSettings objectForKey:GCDAsyncSocketSSLProtocolVersionMin];
        NSString *sslMaxLevel = [tlsSettings objectForKey:GCDAsyncSocketSSLProtocolVersionMax];
        
        if (sslLevel)
        {
            if (sslMinLevel || sslMaxLevel)
            {
                LogWarn(@"kCFStreamSSLLevel security option ignored. Overriden by "
                        @"GCDAsyncSocketSSLProtocolVersionMin and/or GCDAsyncSocketSSLProtocolVersionMax");
            }
            else
            {
                if ([sslLevel isEqualToString:(NSString *)kCFStreamSocketSecurityLevelSSLv3])
                {
                    sslMinLevel = sslMaxLevel = @"kSSLProtocol3";
                }
                else if ([sslLevel isEqualToString:(NSString *)kCFStreamSocketSecurityLevelTLSv1])
                {
                    sslMinLevel = sslMaxLevel = @"kTLSProtocol1";
                }
                else
                {
                    LogWarn(@"Unable to match kCFStreamSSLLevel security option to valid SSL protocol min/max");
                }
            }
        }
        
        if (sslMinLevel || sslMaxLevel)
        {
            OSStatus status1 = noErr;
            OSStatus status2 = noErr;
            
            SSLProtocol (^sslProtocolForString)(NSString*) = ^SSLProtocol (NSString *protocolStr) {
                
                if ([protocolStr isEqualToString:@"kSSLProtocol3"])  return kSSLProtocol3;
                if ([protocolStr isEqualToString:@"kTLSProtocol1"])  return kTLSProtocol1;
                if ([protocolStr isEqualToString:@"kTLSProtocol11"]) return kTLSProtocol11;
                if ([protocolStr isEqualToString:@"kTLSProtocol12"]) return kTLSProtocol12;
                
                return kSSLProtocolUnknown;
            };
            
            SSLProtocol minProtocol = sslProtocolForString(sslMinLevel);
            SSLProtocol maxProtocol = sslProtocolForString(sslMaxLevel);
            
            if (minProtocol != kSSLProtocolUnknown)
            {
                status1 = SSLSetProtocolVersionMin(sslContext, minProtocol);
            }
            if (maxProtocol != kSSLProtocolUnknown)
            {
                status2 = SSLSetProtocolVersionMax(sslContext, maxProtocol);
            }
            
            if (status1 != noErr || status2 != noErr)
            {
                [self closeWithError:[self otherError:@"Error in SSLSetProtocolVersionMinMax"]];
                return;
            }
        }
    }
    #else
    {
        value = [tlsSettings objectForKey:(NSString *)kCFStreamSSLLevel];
        if (value)
        {
            NSString *sslLevel = (NSString *)value;
            
            OSStatus status1 = noErr;
            OSStatus status2 = noErr;
            OSStatus status3 = noErr;
            
            if ([sslLevel isEqualToString:(NSString *)kCFStreamSocketSecurityLevelSSLv2])
            {
                // kCFStreamSocketSecurityLevelSSLv2:
                // 
                // Specifies that SSL version 2 be set as the security protocol.
                
                status1 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocolAll, NO);
                status2 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocol2,   YES);
            }
            else if ([sslLevel isEqualToString:(NSString *)kCFStreamSocketSecurityLevelSSLv3])
            {
                // kCFStreamSocketSecurityLevelSSLv3:
                // 
                // Specifies that SSL version 3 be set as the security protocol.
                // If SSL version 3 is not available, specifies that SSL version 2 be set as the security protocol.
                
                status1 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocolAll, NO);
                status2 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocol2,   YES);
                status3 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocol3,   YES);
            }
            else if ([sslLevel isEqualToString:(NSString *)kCFStreamSocketSecurityLevelTLSv1])
            {
                // kCFStreamSocketSecurityLevelTLSv1:
                // 
                // Specifies that TLS version 1 be set as the security protocol.
                
                status1 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocolAll, NO);
                status2 = SSLSetProtocolVersionEnabled(sslContext, kTLSProtocol1,   YES);
            }
            else if ([sslLevel isEqualToString:(NSString *)kCFStreamSocketSecurityLevelNegotiatedSSL])
            {
                // kCFStreamSocketSecurityLevelNegotiatedSSL:
                // 
                // Specifies that the highest level security protocol that can be negotiated be used.
                
                status1 = SSLSetProtocolVersionEnabled(sslContext, kSSLProtocolAll, YES);
            }
            
            if (status1 != noErr || status2 != noErr || status3 != noErr)
            {
                [self closeWithError:[self otherError:@"Error in SSLSetProtocolVersionEnabled"]];
                return;
            }
        }
    }
    #endif
    
    // 8. GCDAsyncSocketSSLCipherSuites
    
    value = [tlsSettings objectForKey:GCDAsyncSocketSSLCipherSuites];
    if (value)
    {
        NSArray *cipherSuites = (NSArray *)value;
        NSUInteger numberCiphers = [cipherSuites count];
        SSLCipherSuite ciphers[numberCiphers];
        
        NSUInteger cipherIndex;
        for (cipherIndex = 0; cipherIndex < numberCiphers; cipherIndex++)
        {
            NSNumber *cipherObject = [cipherSuites objectAtIndex:cipherIndex];
            ciphers[cipherIndex] = [cipherObject shortValue];
        }
        
        status = SSLSetEnabledCiphers(sslContext, ciphers, numberCiphers);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetEnabledCiphers"]];
            return;
        }
    }
    
    // 9. GCDAsyncSocketSSLDiffieHellmanParameters
    
    #if !TARGET_OS_IPHONE
    value = [tlsSettings objectForKey:GCDAsyncSocketSSLDiffieHellmanParameters];
    if (value)
    {
        NSData *diffieHellmanData = (NSData *)value;
        
        status = SSLSetDiffieHellmanParams(sslContext, [diffieHellmanData bytes], [diffieHellmanData length]);
        if (status != noErr)
        {
            [self closeWithError:[self otherError:@"Error in SSLSetDiffieHellmanParams"]];
            return;
        }
    }
    #endif
    
    // Setup the sslPreBuffer
    // 
    // Any data in the preBuffer needs to be moved into the sslPreBuffer,
    // as this data is now part of the secure read stream.
    
    sslPreBuffer = [[GCDAsyncSocketPreBuffer alloc] initWithCapacity:(1024 * 4)];
    
    size_t preBufferLength  = [preBuffer availableBytes];
    
    if (preBufferLength > 0)
    {
        [sslPreBuffer ensureCapacityForWrite:preBufferLength];
        
        memcpy([sslPreBuffer writeBuffer], [preBuffer readBuffer], preBufferLength);
        [preBuffer didRead:preBufferLength];
        [sslPreBuffer didWrite:preBufferLength];
    }
    
    sslErrCode = noErr;
    
    // Start the SSL Handshake process
    
    [self ssl_continueSSLHandshake];
}

- (void)ssl_continueSSLHandshake
{
    LogTrace();
    
    // If the return value is noErr, the session is ready for normal secure communication.
    // If the return value is errSSLWouldBlock, the SSLHandshake function must be called again.
    // Otherwise, the return value indicates an error code.
    
    OSStatus status = SSLHandshake(sslContext);
    
    if (status == noErr)
    {
        LogVerbose(@"SSLHandshake complete");
        
        flags &= ~kStartingReadTLS;
        flags &= ~kStartingWriteTLS;
        
        flags |=  kSocketSecure;
        
        if (delegateQueue && [delegate respondsToSelector:@selector(socketDidSecure:)])
        {
            __strong id theDelegate = delegate;
            
            dispatch_async(delegateQueue, ^{ @autoreleasepool {
                
                [theDelegate socketDidSecure:self];
            }});
        }
        
        [self endCurrentRead];
        [self endCurrentWrite];
        
        [self maybeDequeueRead];
        [self maybeDequeueWrite];
    }
    else if (status == errSSLWouldBlock)
    {
        LogVerbose(@"SSLHandshake continues...");
        
        // Handshake continues...
        // 
        // This method will be called again from doReadData or doWriteData.
    }
    else
    {
        [self closeWithError:[self sslError:status]];
    }
}

#endif

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Security via CFStream
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#if TARGET_OS_IPHONE

- (void)cf_finishSSLHandshake
{
    LogTrace();
    
    if ((flags & kStartingReadTLS) && (flags & kStartingWriteTLS))
    {
        flags &= ~kStartingReadTLS;
        flags &= ~kStartingWriteTLS;
        
        flags |= kSocketSecure;
        
        if (delegateQueue && [delegate respondsToSelector:@selector(socketDidSecure:)])
        {
            __strong id theDelegate = delegate;
        
            dispatch_async(delegateQueue, ^{ @autoreleasepool {
                
                [theDelegate socketDidSecure:self];
            }});
        }
        
        [self endCurrentRead];
        [self endCurrentWrite];
        
        [self maybeDequeueRead];
        [self maybeDequeueWrite];
    }
}

- (void)cf_abortSSLHandshake:(NSError *)error
{
    LogTrace();
    
    if ((flags & kStartingReadTLS) && (flags & kStartingWriteTLS))
    {
        flags &= ~kStartingReadTLS;
        flags &= ~kStartingWriteTLS;
        
        [self closeWithError:error];
    }
}

- (void)cf_startTLS
{
    LogTrace();
    
    LogVerbose(@"Starting TLS (via CFStream)...");
    
    if ([preBuffer availableBytes] > 0)
    {
        NSString *msg = @"Invalid TLS transition. Handshake has already been read from socket.";
        
        [self closeWithError:[self otherError:msg]];
        return;
    }
    
    [self suspendReadSource];
    [self suspendWriteSource];
    
    socketFDBytesAvailable = 0;
    flags &= ~kSocketCanAcceptBytes;
    flags &= ~kSecureSocketHasBytesAvailable;
    
    flags |=  kUsingCFStreamForTLS;
    
    if (![self createReadAndWriteStream])
    {
        [self closeWithError:[self otherError:@"Error in CFStreamCreatePairWithSocket"]];
        return;
    }
    
    if (![self registerForStreamCallbacksIncludingReadWrite:YES])
    {
        [self closeWithError:[self otherError:@"Error in CFStreamSetClient"]];
        return;
    }
    
    if (![self addStreamsToRunLoop])
    {
        [self closeWithError:[self otherError:@"Error in CFStreamScheduleWithRunLoop"]];
        return;
    }
    
    NSAssert([currentRead isKindOfClass:[GCDAsyncSpecialPacket class]], @"Invalid read packet for startTLS");
    NSAssert([currentWrite isKindOfClass:[GCDAsyncSpecialPacket class]], @"Invalid write packet for startTLS");
    
    GCDAsyncSpecialPacket *tlsPacket = (GCDAsyncSpecialPacket *)currentRead;
    CFDictionaryRef tlsSettings = (__bridge CFDictionaryRef)tlsPacket->tlsSettings;
    
    // Getting an error concerning kCFStreamPropertySSLSettings ?
    // You need to add the CFNetwork framework to your iOS application.
    
    BOOL r1 = CFReadStreamSetProperty(readStream, kCFStreamPropertySSLSettings, tlsSettings);
    BOOL r2 = CFWriteStreamSetProperty(writeStream, kCFStreamPropertySSLSettings, tlsSettings);
    
    // For some reason, starting around the time of iOS 4.3,
    // the first call to set the kCFStreamPropertySSLSettings will return true,
    // but the second will return false.
    // 
    // Order doesn't seem to matter.
    // So you could call CFReadStreamSetProperty and then CFWriteStreamSetProperty, or you could reverse the order.
    // Either way, the first call will return true, and the second returns false.
    // 
    // Interestingly, this doesn't seem to affect anything.
    // Which is not altogether unusual, as the documentation seems to suggest that (for many settings)
    // setting it on one side of the stream automatically sets it for the other side of the stream.
    // 
    // Although there isn't anything in the documentation to suggest that the second attempt would fail.
    // 
    // Furthermore, this only seems to affect streams that are negotiating a security upgrade.
    // In other words, the socket gets connected, there is some back-and-forth communication over the unsecure
    // connection, and then a startTLS is issued.
    // So this mostly affects newer protocols (XMPP, IMAP) as opposed to older protocols (HTTPS).
    
    if (!r1 && !r2) // Yes, the && is correct - workaround for apple bug.
    {
        [self closeWithError:[self otherError:@"Error in CFStreamSetProperty"]];
        return;
    }
    
    if (![self openStreams])
    {
        [self closeWithError:[self otherError:@"Error in CFStreamOpen"]];
        return;
    }
    
    LogVerbose(@"Waiting for SSL Handshake to complete...");
}

#endif

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark CFStream
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

#if TARGET_OS_IPHONE

+ (void)startCFStreamThreadIfNeeded
{
    static dispatch_once_t predicate;
    dispatch_once(&predicate, ^{
        
        cfstreamThread = [[NSThread alloc] initWithTarget:self
                                                 selector:@selector(cfstreamThread)
                                                   object:nil];
        [cfstreamThread start];
    });
}

+ (void)cfstreamThread { @autoreleasepool
{
    [[NSThread currentThread] setName:GCDAsyncSocketThreadName];
    
    LogInfo(@"CFStreamThread: Started");
    
    // We can't run the run loop unless it has an associated input source or a timer.
    // So we'll just create a timer that will never fire - unless the server runs for decades.
    [NSTimer scheduledTimerWithTimeInterval:[[NSDate distantFuture] timeIntervalSinceNow]
                                     target:self
                                   selector:@selector(doNothingAtAll:)
                                   userInfo:nil
                                    repeats:YES];
    
    [[NSRunLoop currentRunLoop] run];
    
    LogInfo(@"CFStreamThread: Stopped");
}}

- (void)doNothingAtAll:(NSTimer *)timer
{
}

+ (void)scheduleCFStreams:(GCDAsyncSocket *)asyncSocket
{
    LogTrace();
    NSAssert([NSThread currentThread] == cfstreamThread, @"Invoked on wrong thread");
    
    CFRunLoopRef runLoop = CFRunLoopGetCurrent();
    
    if (asyncSocket->readStream)
        CFReadStreamScheduleWithRunLoop(asyncSocket->readStream, runLoop, kCFRunLoopDefaultMode);
    
    if (asyncSocket->writeStream)
        CFWriteStreamScheduleWithRunLoop(asyncSocket->writeStream, runLoop, kCFRunLoopDefaultMode);
}

+ (void)unscheduleCFStreams:(GCDAsyncSocket *)asyncSocket
{
    LogTrace();
    NSAssert([NSThread currentThread] == cfstreamThread, @"Invoked on wrong thread");
    
    CFRunLoopRef runLoop = CFRunLoopGetCurrent();
    
    if (asyncSocket->readStream)
        CFReadStreamUnscheduleFromRunLoop(asyncSocket->readStream, runLoop, kCFRunLoopDefaultMode);
    
    if (asyncSocket->writeStream)
        CFWriteStreamUnscheduleFromRunLoop(asyncSocket->writeStream, runLoop, kCFRunLoopDefaultMode);
}

static void CFReadStreamCallback (CFReadStreamRef stream, CFStreamEventType type, void *pInfo)
{
    GCDAsyncSocket *asyncSocket = (__bridge GCDAsyncSocket *)pInfo;
    
    switch(type)
    {
        case kCFStreamEventHasBytesAvailable:
        {
            dispatch_async(asyncSocket->socketQueue, ^{ @autoreleasepool {
                
                LogCVerbose(@"CFReadStreamCallback - HasBytesAvailable");
                
                if (asyncSocket->readStream != stream)
                    return_from_block;
                
                if ((asyncSocket->flags & kStartingReadTLS) && (asyncSocket->flags & kStartingWriteTLS))
                {
                    // If we set kCFStreamPropertySSLSettings before we opened the streams, this might be a lie.
                    // (A callback related to the tcp stream, but not to the SSL layer).
                    
                    if (CFReadStreamHasBytesAvailable(asyncSocket->readStream))
                    {
                        asyncSocket->flags |= kSecureSocketHasBytesAvailable;
                        [asyncSocket cf_finishSSLHandshake];
                    }
                }
                else
                {
                    asyncSocket->flags |= kSecureSocketHasBytesAvailable;
                    [asyncSocket doReadData];
                }
            }});
            
            break;
        }
        default:
        {
            NSError *error = (__bridge_transfer  NSError *)CFReadStreamCopyError(stream);
            
            if (error == nil && type == kCFStreamEventEndEncountered)
            {
                error = [asyncSocket connectionClosedError];
            }
            
            dispatch_async(asyncSocket->socketQueue, ^{ @autoreleasepool {
                
                LogCVerbose(@"CFReadStreamCallback - Other");
                
                if (asyncSocket->readStream != stream)
                    return_from_block;
                
                if ((asyncSocket->flags & kStartingReadTLS) && (asyncSocket->flags & kStartingWriteTLS))
                {
                    [asyncSocket cf_abortSSLHandshake:error];
                }
                else
                {
                    [asyncSocket closeWithError:error];
                }
            }});
            
            break;
        }
    }
    
}

static void CFWriteStreamCallback (CFWriteStreamRef stream, CFStreamEventType type, void *pInfo)
{
    GCDAsyncSocket *asyncSocket = (__bridge GCDAsyncSocket *)pInfo;
    
    switch(type)
    {
        case kCFStreamEventCanAcceptBytes:
        {
            dispatch_async(asyncSocket->socketQueue, ^{ @autoreleasepool {
                
                LogCVerbose(@"CFWriteStreamCallback - CanAcceptBytes");
                
                if (asyncSocket->writeStream != stream)
                    return_from_block;
                
                if ((asyncSocket->flags & kStartingReadTLS) && (asyncSocket->flags & kStartingWriteTLS))
                {
                    // If we set kCFStreamPropertySSLSettings before we opened the streams, this might be a lie.
                    // (A callback related to the tcp stream, but not to the SSL layer).
                    
                    if (CFWriteStreamCanAcceptBytes(asyncSocket->writeStream))
                    {
                        asyncSocket->flags |= kSocketCanAcceptBytes;
                        [asyncSocket cf_finishSSLHandshake];
                    }
                }
                else
                {
                    asyncSocket->flags |= kSocketCanAcceptBytes;
                    [asyncSocket doWriteData];
                }
            }});
            
            break;
        }
        default:
        {
            NSError *error = (__bridge_transfer NSError *)CFWriteStreamCopyError(stream);
            
            if (error == nil && type == kCFStreamEventEndEncountered)
            {
                error = [asyncSocket connectionClosedError];
            }
            
            dispatch_async(asyncSocket->socketQueue, ^{ @autoreleasepool {
                
                LogCVerbose(@"CFWriteStreamCallback - Other");
                
                if (asyncSocket->writeStream != stream)
                    return_from_block;
                
                if ((asyncSocket->flags & kStartingReadTLS) && (asyncSocket->flags & kStartingWriteTLS))
                {
                    [asyncSocket cf_abortSSLHandshake:error];
                }
                else
                {
                    [asyncSocket closeWithError:error];
                }
            }});
            
            break;
        }
    }
    
}

- (BOOL)createReadAndWriteStream
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    
    
    if (readStream || writeStream)
    {
        // Streams already created
        return YES;
    }
    
    int socketFD = (socket6FD == SOCKET_NULL) ? socket4FD : socket6FD;
    
    if (socketFD == SOCKET_NULL)
    {
        // Cannot create streams without a file descriptor
        return NO;
    }
    
    if (![self isConnected])
    {
        // Cannot create streams until file descriptor is connected
        return NO;
    }
    
    LogVerbose(@"Creating read and write stream...");
    
    CFStreamCreatePairWithSocket(NULL, (CFSocketNativeHandle)socketFD, &readStream, &writeStream);
    
    // The kCFStreamPropertyShouldCloseNativeSocket property should be false by default (for our case).
    // But let's not take any chances.
    
    if (readStream)
        CFReadStreamSetProperty(readStream, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanFalse);
    if (writeStream)
        CFWriteStreamSetProperty(writeStream, kCFStreamPropertyShouldCloseNativeSocket, kCFBooleanFalse);
    
    if ((readStream == NULL) || (writeStream == NULL))
    {
        LogWarn(@"Unable to create read and write stream...");
        
        if (readStream)
        {
            CFReadStreamClose(readStream);
            CFRelease(readStream);
            readStream = NULL;
        }
        if (writeStream)
        {
            CFWriteStreamClose(writeStream);
            CFRelease(writeStream);
            writeStream = NULL;
        }
        
        return NO;
    }
    
    return YES;
}

- (BOOL)registerForStreamCallbacksIncludingReadWrite:(BOOL)includeReadWrite
{
    LogVerbose(@"%@ %@", THIS_METHOD, (includeReadWrite ? @"YES" : @"NO"));
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    NSAssert((readStream != NULL && writeStream != NULL), @"Read/Write stream is null");
    
    streamContext.version = 0;
    streamContext.info = (__bridge void *)(self);
    streamContext.retain = nil;
    streamContext.release = nil;
    streamContext.copyDescription = nil;
    
    CFOptionFlags readStreamEvents = kCFStreamEventErrorOccurred | kCFStreamEventEndEncountered;
    if (includeReadWrite)
        readStreamEvents |= kCFStreamEventHasBytesAvailable;
    
    if (!CFReadStreamSetClient(readStream, readStreamEvents, &CFReadStreamCallback, &streamContext))
    {
        return NO;
    }
    
    CFOptionFlags writeStreamEvents = kCFStreamEventErrorOccurred | kCFStreamEventEndEncountered;
    if (includeReadWrite)
        writeStreamEvents |= kCFStreamEventCanAcceptBytes;
    
    if (!CFWriteStreamSetClient(writeStream, writeStreamEvents, &CFWriteStreamCallback, &streamContext))
    {
        return NO;
    }
    
    return YES;
}

- (BOOL)addStreamsToRunLoop
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    NSAssert((readStream != NULL && writeStream != NULL), @"Read/Write stream is null");
    
    if (!(flags & kAddedStreamsToRunLoop))
    {
        LogVerbose(@"Adding streams to runloop...");
        
        [[self class] startCFStreamThreadIfNeeded];
        [[self class] performSelector:@selector(scheduleCFStreams:)
                             onThread:cfstreamThread
                           withObject:self
                        waitUntilDone:YES];
        
        flags |= kAddedStreamsToRunLoop;
    }
    
    return YES;
}

- (void)removeStreamsFromRunLoop
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    NSAssert((readStream != NULL && writeStream != NULL), @"Read/Write stream is null");
    
    if (flags & kAddedStreamsToRunLoop)
    {
        LogVerbose(@"Removing streams from runloop...");
        
        [[self class] performSelector:@selector(unscheduleCFStreams:)
                             onThread:cfstreamThread
                           withObject:self
                        waitUntilDone:YES];
        
        flags &= ~kAddedStreamsToRunLoop;
    }
}

- (BOOL)openStreams
{
    LogTrace();
    
    NSAssert(dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey), @"Must be dispatched on socketQueue");
    NSAssert((readStream != NULL && writeStream != NULL), @"Read/Write stream is null");
    
    CFStreamStatus readStatus = CFReadStreamGetStatus(readStream);
    CFStreamStatus writeStatus = CFWriteStreamGetStatus(writeStream);
    
    if ((readStatus == kCFStreamStatusNotOpen) || (writeStatus == kCFStreamStatusNotOpen))
    {
        LogVerbose(@"Opening read and write stream...");
        
        BOOL r1 = CFReadStreamOpen(readStream);
        BOOL r2 = CFWriteStreamOpen(writeStream);
        
        if (!r1 || !r2)
        {
            LogError(@"Error in CFStreamOpen");
            return NO;
        }
    }
    
    return YES;
}

#endif

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Advanced
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * See header file for big discussion of this method.
**/
- (BOOL)autoDisconnectOnClosedReadStream
{
    // Note: YES means kAllowHalfDuplexConnection is OFF
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        return ((config & kAllowHalfDuplexConnection) == 0);
    }
    else
    {
        __block BOOL result;
        
        dispatch_sync(socketQueue, ^{
            result = ((config & kAllowHalfDuplexConnection) == 0);
        });
        
        return result;
    }
}

/**
 * See header file for big discussion of this method.
**/
- (void)setAutoDisconnectOnClosedReadStream:(BOOL)flag
{
    // Note: YES means kAllowHalfDuplexConnection is OFF
    
    dispatch_block_t block = ^{
        
        if (flag)
            config &= ~kAllowHalfDuplexConnection;
        else
            config |= kAllowHalfDuplexConnection;
    };
    
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_async(socketQueue, block);
}


/**
 * See header file for big discussion of this method.
**/
- (void)markSocketQueueTargetQueue:(dispatch_queue_t)socketNewTargetQueue
{
    void *nonNullUnusedPointer = (__bridge void *)self;
    dispatch_queue_set_specific(socketNewTargetQueue, IsOnSocketQueueOrTargetQueueKey, nonNullUnusedPointer, NULL);
}

/**
 * See header file for big discussion of this method.
**/
- (void)unmarkSocketQueueTargetQueue:(dispatch_queue_t)socketOldTargetQueue
{
    dispatch_queue_set_specific(socketOldTargetQueue, IsOnSocketQueueOrTargetQueueKey, NULL, NULL);
}

/**
 * See header file for big discussion of this method.
**/
- (void)performBlock:(dispatch_block_t)block
{
    if (dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
        block();
    else
        dispatch_sync(socketQueue, block);
}

/**
 * Questions? Have you read the header file?
**/
- (int)socketFD
{
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return SOCKET_NULL;
    }
    
    if (socket4FD != SOCKET_NULL)
        return socket4FD;
    else
        return socket6FD;
}

/**
 * Questions? Have you read the header file?
**/
- (int)socket4FD
{
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return SOCKET_NULL;
    }
    
    return socket4FD;
}

/**
 * Questions? Have you read the header file?
**/
- (int)socket6FD
{
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return SOCKET_NULL;
    }
    
    return socket6FD;
}

#if TARGET_OS_IPHONE

/**
 * Questions? Have you read the header file?
**/
- (CFReadStreamRef)readStream
{
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return NULL;
    }
    
    if (readStream == NULL)
        [self createReadAndWriteStream];
    
    return readStream;
}

/**
 * Questions? Have you read the header file?
**/
- (CFWriteStreamRef)writeStream
{
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return NULL;
    }
    
    if (writeStream == NULL)
        [self createReadAndWriteStream];
    
    return writeStream;
}

- (BOOL)enableBackgroundingOnSocketWithCaveat:(BOOL)caveat
{
    if (![self createReadAndWriteStream])
    {
        // Error occured creating streams (perhaps socket isn't open)
        return NO;
    }
    
    BOOL r1, r2;
    
    LogVerbose(@"Enabling backgrouding on socket");
    
    r1 = CFReadStreamSetProperty(readStream, kCFStreamNetworkServiceType, kCFStreamNetworkServiceTypeVoIP);
    r2 = CFWriteStreamSetProperty(writeStream, kCFStreamNetworkServiceType, kCFStreamNetworkServiceTypeVoIP);
    
    if (!r1 || !r2)
    {
        return NO;
    }
    
    if (!caveat)
    {
        if (![self openStreams])
        {
            return NO;
        }
    }
    
    return YES;
}

/**
 * Questions? Have you read the header file?
**/
- (BOOL)enableBackgroundingOnSocket
{
    LogTrace();
    
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return NO;
    }
    
    return [self enableBackgroundingOnSocketWithCaveat:NO];
}

- (BOOL)enableBackgroundingOnSocketWithCaveat // Deprecated in iOS 4.???
{
    // This method was created as a workaround for a bug in iOS.
    // Apple has since fixed this bug.
    // I'm not entirely sure which version of iOS they fixed it in...
    
    LogTrace();
    
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return NO;
    }
    
    return [self enableBackgroundingOnSocketWithCaveat:YES];
}

#endif

#if SECURE_TRANSPORT_MAYBE_AVAILABLE

- (SSLContextRef)sslContext
{
    if (!dispatch_get_specific(IsOnSocketQueueOrTargetQueueKey))
    {
        LogWarn(@"%@ - Method only available from within the context of a performBlock: invocation", THIS_METHOD);
        return NULL;
    }
    
    return sslContext;
}

#endif

////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
#pragma mark Class Methods
////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

+ (NSString *)hostFromSockaddr4:(const struct sockaddr_in *)pSockaddr4
{
    char addrBuf[INET_ADDRSTRLEN];
    
    if (inet_ntop(AF_INET, &pSockaddr4->sin_addr, addrBuf, (socklen_t)sizeof(addrBuf)) == NULL)
    {
        addrBuf[0] = '\0';
    }
    
    return [NSString stringWithCString:addrBuf encoding:NSASCIIStringEncoding];
}

+ (NSString *)hostFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6
{
    char addrBuf[INET6_ADDRSTRLEN];
    
    if (inet_ntop(AF_INET6, &pSockaddr6->sin6_addr, addrBuf, (socklen_t)sizeof(addrBuf)) == NULL)
    {
        addrBuf[0] = '\0';
    }
    
    return [NSString stringWithCString:addrBuf encoding:NSASCIIStringEncoding];
}

+ (uint16_t)portFromSockaddr4:(const struct sockaddr_in *)pSockaddr4
{
    return ntohs(pSockaddr4->sin_port);
}

+ (uint16_t)portFromSockaddr6:(const struct sockaddr_in6 *)pSockaddr6
{
    return ntohs(pSockaddr6->sin6_port);
}

+ (NSString *)hostFromAddress:(NSData *)address
{
    NSString *host;
    
    if ([self getHost:&host port:NULL fromAddress:address])
        return host;
    else
        return nil;
}

+ (uint16_t)portFromAddress:(NSData *)address
{
    uint16_t port;
    
    if ([self getHost:NULL port:&port fromAddress:address])
        return port;
    else
        return 0;
}

+ (BOOL)getHost:(NSString **)hostPtr port:(uint16_t *)portPtr fromAddress:(NSData *)address
{
    if ([address length] >= sizeof(struct sockaddr))
    {
        const struct sockaddr *sockaddrX = [address bytes];
        
        if (sockaddrX->sa_family == AF_INET)
        {
            if ([address length] >= sizeof(struct sockaddr_in))
            {
                struct sockaddr_in sockaddr4;
                memcpy(&sockaddr4, sockaddrX, sizeof(sockaddr4));
                
                if (hostPtr) *hostPtr = [self hostFromSockaddr4:&sockaddr4];
                if (portPtr) *portPtr = [self portFromSockaddr4:&sockaddr4];
                
                return YES;
            }
        }
        else if (sockaddrX->sa_family == AF_INET6)
        {
            if ([address length] >= sizeof(struct sockaddr_in6))
            {
                struct sockaddr_in6 sockaddr6;
                memcpy(&sockaddr6, sockaddrX, sizeof(sockaddr6));
                
                if (hostPtr) *hostPtr = [self hostFromSockaddr6:&sockaddr6];
                if (portPtr) *portPtr = [self portFromSockaddr6:&sockaddr6];
                
                return YES;
            }
        }
    }
    
    return NO;
}

+ (NSData *)CRLFData
{
    return [NSData dataWithBytes:"\x0D\x0A" length:2];
}

+ (NSData *)CRData
{
    return [NSData dataWithBytes:"\x0D" length:1];
}

+ (NSData *)LFData
{
    return [NSData dataWithBytes:"\x0A" length:1];
}

+ (NSData *)ZeroData
{
    return [NSData dataWithBytes:"" length:1];
}

@end