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/*
* FreeRTOS+UDP V1.0.3 (C) 2014 Real Time Engineers ltd.
* All rights reserved
*
* This file is part of the FreeRTOS+UDP distribution. The FreeRTOS+UDP license
* terms are different to the FreeRTOS license terms.
*
* FreeRTOS+UDP uses a dual license model that allows the software to be used
* under a standard GPL open source license, or a commercial license. The
* standard GPL license (unlike the modified GPL license under which FreeRTOS
* itself is distributed) requires that all software statically linked with
* FreeRTOS+UDP is also distributed under the same GPL V2 license terms.
* Details of both license options follow:
*
* - Open source licensing -
* FreeRTOS+UDP is a free download and may be used, modified, evaluated and
* distributed without charge provided the user adheres to version two of the
* GNU General Public License (GPL) and does not remove the copyright notice or
* this text. The GPL V2 text is available on the gnu.org web site, and on the
* following URL: http://www.FreeRTOS.org/gpl-2.0.txt.
*
* - Commercial licensing -
* Businesses and individuals that for commercial or other reasons cannot comply
* with the terms of the GPL V2 license must obtain a commercial license before
* incorporating FreeRTOS+UDP into proprietary software for distribution in any
* form. Commercial licenses can be purchased from http://shop.freertos.org/udp
* and do not require any source files to be changed.
*
* FreeRTOS+UDP is distributed in the hope that it will be useful. You cannot
* use FreeRTOS+UDP unless you agree that you use the software 'as is'.
* FreeRTOS+UDP is provided WITHOUT ANY WARRANTY; without even the implied
* warranties of NON-INFRINGEMENT, MERCHANTABILITY or FITNESS FOR A PARTICULAR
* PURPOSE. Real Time Engineers Ltd. disclaims all conditions and terms, be they
* implied, expressed, or statutory.
*
* 1 tab == 4 spaces!
*
* http://www.FreeRTOS.org
* http://www.FreeRTOS.org/udp
*
*/
/* Standard includes. */
#include <stdint.h>
/* FreeRTOS includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "timers.h"
/* FreeRTOS+UDP includes. */
#include "FreeRTOS_UDP_IP.h"
#include "FreeRTOS_IP_Private.h"
#include "FreeRTOS_DNS.h"
#include "FreeRTOS_Sockets.h"
#include "NetworkInterface.h"
#include "IPTraceMacroDefaults.h"
/* Exclude the entire file if DNS is not enabled. */
#if ipconfigUSE_DNS != 0
#if( ipconfigBYTE_ORDER == FREERTOS_LITTLE_ENDIAN )
#define dnsOUTGOING_FLAGS 0x0001 /* Standard query. */
#define dnsTYPE 0x0100 /* A record (host address. */
#define dnsCLASS 0x0100 /* IN */
#define dnsDNS_PORT 0x3500
#define dnsONE_QUESTION 0x0100
#define dnsRX_FLAGS_MASK 0x0f80 /* The bits of interest in the flags field of incoming DNS messages. */
#define dnsEXPECTED_RX_FLAGS 0x0080 /* Should be a response, without any errors. */
#else
#define dnsDNS_PORT 0x35
#define dnsONE_QUESTION 0x01
#define dnsFLAG_QUERY_RESPONSE_BIT 0x8000
#define dnsFLAG_OPERATION_CODE_BITS 0x7800
#define dnsFLAG_TRUNCATION_BIT 0x0200
#define dnsFLAG_RESPONSE_CODE_BITS 0x000f
#define dnsOUTGOING_FLAGS 0x0100 /* Standard query. */
#define dnsTYPE 0x0001 /* A record (host address. */
#define dnsCLASS 0x0001 /* IN */
#define dnsRX_FLAGS_MASK 0x800f /* The bits of interest in the flags field of incoming DNS messages. */
#define dnsEXPECTED_RX_FLAGS 0x8000 /* Should be a response, without any errors. */
#endif /* ipconfigBYTE_ORDER */
/* The maximum number of times a DNS request should be sent out if a response
is not received, before giving up. */
#define dnsMAX_REQUEST_ATTEMPTS 5
/* If the top two bits in the first character of a name field are set then the
name field is an offset to the string, rather than the string itself. */
#define dnsNAME_IS_OFFSET ( ( uint8_t ) 0xc0 )
/*
* Create a socket and bind it to the standard DNS port number. Return the
* the created socket - or NULL if the socket could not be created or bound.
*/
static xSocket_t prvCreateDNSSocket( void );
/*
* Create the DNS message in the zero copy buffer passed in the first parameter.
*/
static size_t prvCreateDNSMessage( uint8_t *pucUDPPayloadBuffer, const char *pcHostName, uint16_t usIdentifier );
/*
* Simple routine that jumps over the NAME field of a resource record.
*/
static uint8_t *prvSkipNameField( uint8_t *pucByte );
/*
* Process a response packet from a DNS server.
*/
static uint32_t prvParseDNSReply( uint8_t *pucUDPPayloadBuffer, uint16_t usIdentifier );
/*-----------------------------------------------------------*/
#include "pack_struct_start.h"
struct xDNSMessage
{
uint16_t usIdentifier;
uint16_t usFlags;
uint16_t usQuestions;
uint16_t usAnswers;
uint16_t usAuthorityRRs;
uint16_t usAdditionalRRs;
}
#include "pack_struct_end.h"
typedef struct xDNSMessage xDNSMessage_t;
/*-----------------------------------------------------------*/
uint32_t FreeRTOS_gethostbyname( const char *pcHostName )
{
static uint16_t usIdentifier = 0;
struct freertos_sockaddr xAddress;
static xSocket_t xDNSSocket = NULL;
uint32_t ulIPAddress = 0UL;
uint8_t *pucUDPPayloadBuffer;
static uint32_t ulAddressLength;
portBASE_TYPE xAttempt;
int32_t lBytes;
size_t xPayloadLength;
const size_t xExpectedPayloadLength = sizeof( xDNSMessage_t ) + strlen( pcHostName ) + sizeof( uint16_t ) + sizeof( uint16_t ) + 2; /* Two for the count of characters in the first subdomain part, and the string end byte */
if( xDNSSocket == NULL )
{
xDNSSocket = prvCreateDNSSocket();
}
if( xDNSSocket != NULL )
{
/* Generate a unique identifier for this query. */
usIdentifier++;
for( xAttempt = 0; xAttempt < dnsMAX_REQUEST_ATTEMPTS; xAttempt++ )
{
/* Get a buffer. This uses a maximum delay, but the delay will be
capped to ipconfigMAX_SEND_BLOCK_TIME_TICKS so the return value
still needs to be tested. */
pucUDPPayloadBuffer = ( uint8_t * ) FreeRTOS_GetUDPPayloadBuffer( xExpectedPayloadLength, portMAX_DELAY );
if( pucUDPPayloadBuffer != NULL )
{
/* Create the message in the obtained buffer. */
xPayloadLength = prvCreateDNSMessage( pucUDPPayloadBuffer, pcHostName, usIdentifier );
iptraceSENDING_DNS_REQUEST();
/* Obtain the DNS server address. */
FreeRTOS_GetAddressConfiguration( NULL, NULL, NULL, &ulIPAddress );
/* Send the DNS message. */
xAddress.sin_addr = ulIPAddress;
xAddress.sin_port = dnsDNS_PORT;
ulIPAddress = 0;
if( FreeRTOS_sendto( xDNSSocket, pucUDPPayloadBuffer, xPayloadLength, FREERTOS_ZERO_COPY, &xAddress, sizeof( xAddress ) ) != 0 )
{
/* Wait for the reply. */
lBytes = FreeRTOS_recvfrom( xDNSSocket, &pucUDPPayloadBuffer, 0, FREERTOS_ZERO_COPY, &xAddress, &ulAddressLength );
if( lBytes > 0 )
{
/* The reply was received. Process it. */
ulIPAddress = prvParseDNSReply( pucUDPPayloadBuffer, usIdentifier );
/* Finished with the buffer. The zero copy interface
is being used, so the buffer must be freed by the
task. */
FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucUDPPayloadBuffer );
if( ulIPAddress != 0 )
{
/* All done. */
break;
}
}
}
else
{
/* The message was not sent so the stack will not be
releasing the zero copy - it must be released here. */
FreeRTOS_ReleaseUDPPayloadBuffer( ( void * ) pucUDPPayloadBuffer );
}
}
}
}
return ulIPAddress;
}
/*-----------------------------------------------------------*/
static size_t prvCreateDNSMessage( uint8_t *pucUDPPayloadBuffer, const char *pcHostName, uint16_t usIdentifier )
{
xDNSMessage_t *pxDNSMessageHeader;
uint8_t *pucStart, *pucByte;
const uint16_t usARecordType = dnsTYPE, usClass = dnsCLASS;
static const xDNSMessage_t xDefaultPartDNSHeader =
{
0, /* The identifier will be overwritten. */
dnsOUTGOING_FLAGS, /* Flags set for standard query. */
dnsONE_QUESTION, /* One question is being asked. */
0, /* No replies are included. */
0, /* No authorities. */
0 /* No additional authorities. */
};
/* Copy in the const part of the header. */
memcpy( ( void * ) pucUDPPayloadBuffer, ( void * ) &xDefaultPartDNSHeader, sizeof( xDefaultPartDNSHeader ) );
/* Write in a unique identifier. */
pxDNSMessageHeader = ( xDNSMessage_t * ) pucUDPPayloadBuffer;
pxDNSMessageHeader->usIdentifier = usIdentifier;
/* Create the resource record at the end of the header. First
find the end of the header. */
pucStart = pucUDPPayloadBuffer + sizeof( xDefaultPartDNSHeader );
/* Leave a gap for the first length bytes. */
pucByte = pucStart + 1;
/* Copy in the host name. */
strcpy( ( char * ) pucByte, pcHostName );
/* Mark the end of the string. */
pucByte += strlen( pcHostName );
*pucByte = 0x00;
/* Walk the string to replace the '.' characters with byte counts.
pucStart holds the address of the byte count. Walking the string
starts after the byte count position. */
pucByte = pucStart;
do
{
pucByte++;
while( ( *pucByte != 0x00 ) && ( *pucByte != '.' ) )
{
pucByte++;
}
/* Fill in the byte count, then move the pucStart pointer up to
the found byte position. */
*pucStart = ( uint8_t ) ( ( uint32_t ) pucByte - ( uint32_t ) pucStart );
( *pucStart )--;
pucStart = pucByte;
} while( *pucByte != 0x00 );
/* Finish off the record. */
pucByte++;
memcpy( ( void * ) pucByte, &usARecordType, sizeof( uint16_t ) );
pucByte += sizeof( uint16_t );
memcpy( ( void * ) pucByte, &usClass, sizeof( uint16_t ) );
pucByte += sizeof( uint16_t );
/* Return the total size of the generated message, which is the space from
the last written byte to the beginning of the buffer. */
return ( ( uint32_t ) pucByte - ( uint32_t ) pucUDPPayloadBuffer );
}
/*-----------------------------------------------------------*/
static uint8_t *prvSkipNameField( uint8_t *pucByte )
{
/* Determine if the name is the fully coded name, or an offset to the name
elsewhere in the message. */
if( ( *pucByte & dnsNAME_IS_OFFSET ) == dnsNAME_IS_OFFSET )
{
/* Jump over the two byte offset. */
pucByte += sizeof( uint16_t );
}
else
{
/* pucByte points to the full name. Walk over the string. */
while( *pucByte != 0x00 )
{
/* The number of bytes to jump for each name section is stored in the byte
before the name section. */
pucByte += ( *pucByte + 1 );
}
pucByte++;
}
return pucByte;
}
/*-----------------------------------------------------------*/
static uint32_t prvParseDNSReply( uint8_t *pucUDPPayloadBuffer, uint16_t usIdentifier )
{
xDNSMessage_t *pxDNSMessageHeader;
uint32_t ulIPAddress = 0UL;
uint8_t *pucByte;
uint16_t x, usDataLength;
const uint16_t usARecordType = dnsTYPE;
pxDNSMessageHeader = ( xDNSMessage_t * ) pucUDPPayloadBuffer;
if( pxDNSMessageHeader->usIdentifier == usIdentifier )
{
if( ( pxDNSMessageHeader->usFlags & dnsRX_FLAGS_MASK ) == dnsEXPECTED_RX_FLAGS )
{
/* Start at the first byte after the header. */
pucByte = pucUDPPayloadBuffer + sizeof( xDNSMessage_t );
/* Skip any question records. */
pxDNSMessageHeader->usQuestions = FreeRTOS_ntohs( pxDNSMessageHeader->usQuestions );
for( x = 0; x < pxDNSMessageHeader->usQuestions; x++ )
{
/* Skip the variable length name field. */
pucByte = prvSkipNameField( pucByte );
/* Skip the type and class fields. */
pucByte += sizeof( uint32_t );
}
/* Search through the answers records. */
pxDNSMessageHeader->usAnswers = FreeRTOS_ntohs( pxDNSMessageHeader->usAnswers );
for( x = 0; x < pxDNSMessageHeader->usAnswers; x++ )
{
pucByte = prvSkipNameField( pucByte );
/* Is the type field that of an A record? */
if( memcmp( ( void * ) pucByte, ( void * ) &usARecordType, sizeof( uint16_t ) ) == 0 )
{
/* This is the required record. Skip the type, class, and
time to live fields, plus the first byte of the data
length. */
pucByte += ( sizeof( uint32_t ) + sizeof( uint32_t ) + sizeof( uint8_t ) );
/* Sanity check the data length. */
if( *pucByte == sizeof( uint32_t ) )
{
/* Skip the second byte of the length. */
pucByte++;
/* Copy the IP address out of the record. */
memcpy( ( void * ) &ulIPAddress, ( void * ) pucByte, sizeof( uint32_t ) );
}
break;
}
else
{
/* Skip the type, class and time to live fields. */
pucByte += ( sizeof( uint32_t ) + sizeof( uint32_t ) );
/* Determine the length of the data in the field. */
memcpy( ( void * ) &usDataLength, ( void * ) pucByte, sizeof( uint16_t ) );
usDataLength = FreeRTOS_ntohs( usDataLength );
/* Jump over the data lenth bytes, and the data itself. */
pucByte += usDataLength + sizeof( uint16_t );
}
}
}
}
return ulIPAddress;
}
/*-----------------------------------------------------------*/
static xSocket_t prvCreateDNSSocket( void )
{
static xSocket_t xSocket = NULL;
struct freertos_sockaddr xAddress;
portBASE_TYPE xReturn;
portTickType xTimeoutTime = 200 / portTICK_RATE_MS;
/* This must be the first time this function has been called. Create
the socket. */
xSocket = FreeRTOS_socket( FREERTOS_AF_INET, FREERTOS_SOCK_DGRAM, FREERTOS_IPPROTO_UDP );
/* Auto bind the port. */
xAddress.sin_port = 0;
xReturn = FreeRTOS_bind( xSocket, &xAddress, sizeof( xAddress ) );
/* Check the bind was successful, and clean up if not. */
if( xReturn != 0 )
{
FreeRTOS_closesocket( xSocket );
xSocket = NULL;
}
else
{
/* Set the send and receive timeouts. */
FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_RCVTIMEO, ( void * ) &xTimeoutTime, sizeof( portTickType ) );
FreeRTOS_setsockopt( xSocket, 0, FREERTOS_SO_SNDTIMEO, ( void * ) &xTimeoutTime, sizeof( portTickType ) );
}
return xSocket;
}
#endif /* ipconfigUSE_DNS != 0 */