arm/usr/lib/rustlib/src/rust/library/std/src/net/parser.rs - manifest_repos/toolchain - Git at Google

 //! A private parser implementation of IPv4, IPv6, and socket addresses.
 //!
 //! This module is "publicly exported" through the `FromStr` implementations
 //! below.

 #[cfg(test)]
 mod tests;

 use crate::error::Error;
 use crate::fmt;
 use crate::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
 use crate::str::FromStr;

 trait ReadNumberHelper: crate::marker::Sized {
     const ZERO: Self;
     fn checked_mul(&self, other: u32) -> Option<Self>;
     fn checked_add(&self, other: u32) -> Option<Self>;
 }

 macro_rules! impl_helper {
     ($($t:ty)*) => ($(impl ReadNumberHelper for $t {
         const ZERO: Self = 0;
         #[inline]
         fn checked_mul(&self, other: u32) -> Option<Self> {
             Self::checked_mul(*self, other.try_into().ok()?)
         }
         #[inline]
         fn checked_add(&self, other: u32) -> Option<Self> {
             Self::checked_add(*self, other.try_into().ok()?)
         }
     })*)
 }

 impl_helper! { u8 u16 u32 }

 struct Parser<'a> {
     // Parsing as ASCII, so can use byte array.
     state: &'a [u8],
 }

 impl<'a> Parser<'a> {
     fn new(input: &'a [u8]) -> Parser<'a> {
         Parser { state: input }
     }

     /// Run a parser, and restore the pre-parse state if it fails.
     fn read_atomically<T, F>(&mut self, inner: F) -> Option<T>
     where
         F: FnOnce(&mut Parser<'_>) -> Option<T>,
     {
         let state = self.state;
         let result = inner(self);
         if result.is_none() {
             self.state = state;
         }
         result
     }

     /// Run a parser, but fail if the entire input wasn't consumed.
     /// Doesn't run atomically.
     fn parse_with<T, F>(&mut self, inner: F, kind: AddrKind) -> Result<T, AddrParseError>
     where
         F: FnOnce(&mut Parser<'_>) -> Option<T>,
     {
         let result = inner(self);
         if self.state.is_empty() { result } else { None }.ok_or(AddrParseError(kind))
     }

     /// Peek the next character from the input
     fn peek_char(&self) -> Option<char> {
         self.state.first().map(|&b| char::from(b))
     }

     /// Read the next character from the input
     fn read_char(&mut self) -> Option<char> {
         self.state.split_first().map(|(&b, tail)| {
             self.state = tail;
             char::from(b)
         })
     }

     #[must_use]
     /// Read the next character from the input if it matches the target.
     fn read_given_char(&mut self, target: char) -> Option<()> {
         self.read_atomically(|p| {
             p.read_char().and_then(|c| if c == target { Some(()) } else { None })
         })
     }

     /// Helper for reading separators in an indexed loop. Reads the separator
     /// character iff index > 0, then runs the parser. When used in a loop,
     /// the separator character will only be read on index > 0 (see
     /// read_ipv4_addr for an example)
     fn read_separator<T, F>(&mut self, sep: char, index: usize, inner: F) -> Option<T>
     where
         F: FnOnce(&mut Parser<'_>) -> Option<T>,
     {
         self.read_atomically(move |p| {
             if index > 0 {
                 p.read_given_char(sep)?;
             }
             inner(p)
         })
     }

     // Read a number off the front of the input in the given radix, stopping
     // at the first non-digit character or eof. Fails if the number has more
     // digits than max_digits or if there is no number.
     fn read_number<T: ReadNumberHelper>(
         &mut self,
         radix: u32,
         max_digits: Option<usize>,
         allow_zero_prefix: bool,
     ) -> Option<T> {
         self.read_atomically(move |p| {
             let mut result = T::ZERO;
             let mut digit_count = 0;
             let has_leading_zero = p.peek_char() == Some('0');

             while let Some(digit) = p.read_atomically(|p| p.read_char()?.to_digit(radix)) {
                 result = result.checked_mul(radix)?;
                 result = result.checked_add(digit)?;
                 digit_count += 1;
                 if let Some(max_digits) = max_digits {
                     if digit_count > max_digits {
                         return None;
                     }
                 }
             }

             if digit_count == 0 {
                 None
             } else if !allow_zero_prefix && has_leading_zero && digit_count > 1 {
                 None
             } else {
                 Some(result)
             }
         })
     }

     /// Read an IPv4 address.
     fn read_ipv4_addr(&mut self) -> Option<Ipv4Addr> {
         self.read_atomically(|p| {
             let mut groups = [0; 4];

             for (i, slot) in groups.iter_mut().enumerate() {
                 *slot = p.read_separator('.', i, |p| {
                     // Disallow octal number in IP string.
                     // https://tools.ietf.org/html/rfc6943#section-3.1.1
                     p.read_number(10, Some(3), false)
                 })?;
             }

             Some(groups.into())
         })
     }

     /// Read an IPv6 Address.
     fn read_ipv6_addr(&mut self) -> Option<Ipv6Addr> {
         /// Read a chunk of an IPv6 address into `groups`. Returns the number
         /// of groups read, along with a bool indicating if an embedded
         /// trailing IPv4 address was read. Specifically, read a series of
         /// colon-separated IPv6 groups (0x0000 - 0xFFFF), with an optional
         /// trailing embedded IPv4 address.
         fn read_groups(p: &mut Parser<'_>, groups: &mut [u16]) -> (usize, bool) {
             let limit = groups.len();

             for (i, slot) in groups.iter_mut().enumerate() {
                 // Try to read a trailing embedded IPv4 address. There must be
                 // at least two groups left.
                 if i < limit - 1 {
                     let ipv4 = p.read_separator(':', i, |p| p.read_ipv4_addr());

                     if let Some(v4_addr) = ipv4 {
                         let [one, two, three, four] = v4_addr.octets();
                         groups[i + 0] = u16::from_be_bytes([one, two]);
                         groups[i + 1] = u16::from_be_bytes([three, four]);
                         return (i + 2, true);
                     }
                 }

                 let group = p.read_separator(':', i, |p| p.read_number(16, Some(4), true));

                 match group {
                     Some(g) => *slot = g,
                     None => return (i, false),
                 }
             }
             (groups.len(), false)
         }

         self.read_atomically(|p| {
             // Read the front part of the address; either the whole thing, or up
             // to the first ::
             let mut head = [0; 8];
             let (head_size, head_ipv4) = read_groups(p, &mut head);

             if head_size == 8 {
                 return Some(head.into());
             }

             // IPv4 part is not allowed before `::`
             if head_ipv4 {
                 return None;
             }

             // Read `::` if previous code parsed less than 8 groups.
             // `::` indicates one or more groups of 16 bits of zeros.
             p.read_given_char(':')?;
             p.read_given_char(':')?;

             // Read the back part of the address. The :: must contain at least one
             // set of zeroes, so our max length is 7.
             let mut tail = [0; 7];
             let limit = 8 - (head_size + 1);
             let (tail_size, _) = read_groups(p, &mut tail[..limit]);

             // Concat the head and tail of the IP address
             head[(8 - tail_size)..8].copy_from_slice(&tail[..tail_size]);

             Some(head.into())
         })
     }

     /// Read an IP Address, either IPv4 or IPv6.
     fn read_ip_addr(&mut self) -> Option<IpAddr> {
         self.read_ipv4_addr().map(IpAddr::V4).or_else(move || self.read_ipv6_addr().map(IpAddr::V6))
     }

     /// Read a `:` followed by a port in base 10.
     fn read_port(&mut self) -> Option<u16> {
         self.read_atomically(|p| {
             p.read_given_char(':')?;
             p.read_number(10, None, true)
         })
     }

     /// Read a `%` followed by a scope ID in base 10.
     fn read_scope_id(&mut self) -> Option<u32> {
         self.read_atomically(|p| {
             p.read_given_char('%')?;
             p.read_number(10, None, true)
         })
     }

     /// Read an IPv4 address with a port.
     fn read_socket_addr_v4(&mut self) -> Option<SocketAddrV4> {
         self.read_atomically(|p| {
             let ip = p.read_ipv4_addr()?;
             let port = p.read_port()?;
             Some(SocketAddrV4::new(ip, port))
         })
     }

     /// Read an IPv6 address with a port.
     fn read_socket_addr_v6(&mut self) -> Option<SocketAddrV6> {
         self.read_atomically(|p| {
             p.read_given_char('[')?;
             let ip = p.read_ipv6_addr()?;
             let scope_id = p.read_scope_id().unwrap_or(0);
             p.read_given_char(']')?;

             let port = p.read_port()?;
             Some(SocketAddrV6::new(ip, port, 0, scope_id))
         })
     }

     /// Read an IP address with a port
     fn read_socket_addr(&mut self) -> Option<SocketAddr> {
         self.read_socket_addr_v4()
             .map(SocketAddr::V4)
             .or_else(|| self.read_socket_addr_v6().map(SocketAddr::V6))
     }
 }

 impl IpAddr {
     /// Parse an IP address from a slice of bytes.
     ///
     /// ```
     /// #![feature(addr_parse_ascii)]
     ///
     /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
     ///
     /// let localhost_v4 = IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1));
     /// let localhost_v6 = IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
     ///
     /// assert_eq!(IpAddr::parse_ascii(b"127.0.0.1"), Ok(localhost_v4));
     /// assert_eq!(IpAddr::parse_ascii(b"::1"), Ok(localhost_v6));
     /// ```
     #[unstable(feature = "addr_parse_ascii", issue = "101035")]
     pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         Parser::new(b).parse_with(|p| p.read_ip_addr(), AddrKind::Ip)
     }
 }

 #[stable(feature = "ip_addr", since = "1.7.0")]
 impl FromStr for IpAddr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<IpAddr, AddrParseError> {
         Self::parse_ascii(s.as_bytes())
     }
 }

 impl Ipv4Addr {
     /// Parse an IPv4 address from a slice of bytes.
     ///
     /// ```
     /// #![feature(addr_parse_ascii)]
     ///
     /// use std::net::Ipv4Addr;
     ///
     /// let localhost = Ipv4Addr::new(127, 0, 0, 1);
     ///
     /// assert_eq!(Ipv4Addr::parse_ascii(b"127.0.0.1"), Ok(localhost));
     /// ```
     #[unstable(feature = "addr_parse_ascii", issue = "101035")]
     pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         // don't try to parse if too long
         if b.len() > 15 {
             Err(AddrParseError(AddrKind::Ipv4))
         } else {
             Parser::new(b).parse_with(|p| p.read_ipv4_addr(), AddrKind::Ipv4)
         }
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromStr for Ipv4Addr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<Ipv4Addr, AddrParseError> {
         Self::parse_ascii(s.as_bytes())
     }
 }

 impl Ipv6Addr {
     /// Parse an IPv6 address from a slice of bytes.
     ///
     /// ```
     /// #![feature(addr_parse_ascii)]
     ///
     /// use std::net::Ipv6Addr;
     ///
     /// let localhost = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
     ///
     /// assert_eq!(Ipv6Addr::parse_ascii(b"::1"), Ok(localhost));
     /// ```
     #[unstable(feature = "addr_parse_ascii", issue = "101035")]
     pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         Parser::new(b).parse_with(|p| p.read_ipv6_addr(), AddrKind::Ipv6)
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromStr for Ipv6Addr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<Ipv6Addr, AddrParseError> {
         Self::parse_ascii(s.as_bytes())
     }
 }

 impl SocketAddrV4 {
     /// Parse an IPv4 socket address from a slice of bytes.
     ///
     /// ```
     /// #![feature(addr_parse_ascii)]
     ///
     /// use std::net::{Ipv4Addr, SocketAddrV4};
     ///
     /// let socket = SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080);
     ///
     /// assert_eq!(SocketAddrV4::parse_ascii(b"127.0.0.1:8080"), Ok(socket));
     /// ```
     #[unstable(feature = "addr_parse_ascii", issue = "101035")]
     pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         Parser::new(b).parse_with(|p| p.read_socket_addr_v4(), AddrKind::SocketV4)
     }
 }

 #[stable(feature = "socket_addr_from_str", since = "1.5.0")]
 impl FromStr for SocketAddrV4 {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<SocketAddrV4, AddrParseError> {
         Self::parse_ascii(s.as_bytes())
     }
 }

 impl SocketAddrV6 {
     /// Parse an IPv6 socket address from a slice of bytes.
     ///
     /// ```
     /// #![feature(addr_parse_ascii)]
     ///
     /// use std::net::{Ipv6Addr, SocketAddrV6};
     ///
     /// let socket = SocketAddrV6::new(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1), 8080, 0, 0);
     ///
     /// assert_eq!(SocketAddrV6::parse_ascii(b"[2001:db8::1]:8080"), Ok(socket));
     /// ```
     #[unstable(feature = "addr_parse_ascii", issue = "101035")]
     pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         Parser::new(b).parse_with(|p| p.read_socket_addr_v6(), AddrKind::SocketV6)
     }
 }

 #[stable(feature = "socket_addr_from_str", since = "1.5.0")]
 impl FromStr for SocketAddrV6 {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<SocketAddrV6, AddrParseError> {
         Self::parse_ascii(s.as_bytes())
     }
 }

 impl SocketAddr {
     /// Parse a socket address from a slice of bytes.
     ///
     /// ```
     /// #![feature(addr_parse_ascii)]
     ///
     /// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
     ///
     /// let socket_v4 = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 8080);
     /// let socket_v6 = SocketAddr::new(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1)), 8080);
     ///
     /// assert_eq!(SocketAddr::parse_ascii(b"127.0.0.1:8080"), Ok(socket_v4));
     /// assert_eq!(SocketAddr::parse_ascii(b"[::1]:8080"), Ok(socket_v6));
     /// ```
     #[unstable(feature = "addr_parse_ascii", issue = "101035")]
     pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
         Parser::new(b).parse_with(|p| p.read_socket_addr(), AddrKind::Socket)
     }
 }

 #[stable(feature = "rust1", since = "1.0.0")]
 impl FromStr for SocketAddr {
     type Err = AddrParseError;
     fn from_str(s: &str) -> Result<SocketAddr, AddrParseError> {
         Self::parse_ascii(s.as_bytes())
     }
 }

 #[derive(Debug, Clone, PartialEq, Eq)]
 enum AddrKind {
     Ip,
     Ipv4,
     Ipv6,
     Socket,
     SocketV4,
     SocketV6,
 }

 /// An error which can be returned when parsing an IP address or a socket address.
 ///
 /// This error is used as the error type for the [`FromStr`] implementation for
 /// [`IpAddr`], [`Ipv4Addr`], [`Ipv6Addr`], [`SocketAddr`], [`SocketAddrV4`], and
 /// [`SocketAddrV6`].
 ///
 /// # Potential causes
 ///
 /// `AddrParseError` may be thrown because the provided string does not parse as the given type,
 /// often because it includes information only handled by a different address type.
 ///
 /// ```should_panic
 /// use std::net::IpAddr;
 /// let _foo: IpAddr = "127.0.0.1:8080".parse().expect("Cannot handle the socket port");
 /// ```
 ///
 /// [`IpAddr`] doesn't handle the port. Use [`SocketAddr`] instead.
 ///
 /// ```
 /// use std::net::SocketAddr;
 ///
 /// // No problem, the `panic!` message has disappeared.
 /// let _foo: SocketAddr = "127.0.0.1:8080".parse().expect("unreachable panic");
 /// ```
 #[stable(feature = "rust1", since = "1.0.0")]
 #[derive(Debug, Clone, PartialEq, Eq)]
 pub struct AddrParseError(AddrKind);

 #[stable(feature = "addr_parse_error_error", since = "1.4.0")]
 impl fmt::Display for AddrParseError {
     #[allow(deprecated, deprecated_in_future)]
     fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
         fmt.write_str(self.description())
     }
 }

 #[stable(feature = "addr_parse_error_error", since = "1.4.0")]
 impl Error for AddrParseError {
     #[allow(deprecated)]
     fn description(&self) -> &str {
         match self.0 {
             AddrKind::Ip => "invalid IP address syntax",
             AddrKind::Ipv4 => "invalid IPv4 address syntax",
             AddrKind::Ipv6 => "invalid IPv6 address syntax",
             AddrKind::Socket => "invalid socket address syntax",
             AddrKind::SocketV4 => "invalid IPv4 socket address syntax",
             AddrKind::SocketV6 => "invalid IPv6 socket address syntax",
         }
     }
 }
	//! A private parser implementation of IPv4, IPv6, and socket addresses.
	//!
	//! This module is "publicly exported" through the `FromStr` implementations
	//! below.

	#[cfg(test)]
	mod tests;

	use crate::error::Error;
	use crate::fmt;
	use crate::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6};
	use crate::str::FromStr;

	trait ReadNumberHelper: crate::marker::Sized {
	const ZERO: Self;
	fn checked_mul(&self, other: u32) -> Option<Self>;
	fn checked_add(&self, other: u32) -> Option<Self>;
	}

	macro_rules! impl_helper {
	($($t:ty)*) => ($(impl ReadNumberHelper for $t {
	const ZERO: Self = 0;
	#[inline]
	fn checked_mul(&self, other: u32) -> Option<Self> {
	Self::checked_mul(*self, other.try_into().ok()?)
	}
	#[inline]
	fn checked_add(&self, other: u32) -> Option<Self> {
	Self::checked_add(*self, other.try_into().ok()?)
	}
	})*)
	}

	impl_helper! { u8 u16 u32 }

	struct Parser<'a> {
	// Parsing as ASCII, so can use byte array.
	state: &'a [u8],
	}

	impl<'a> Parser<'a> {
	fn new(input: &'a [u8]) -> Parser<'a> {
	Parser { state: input }
	}

	/// Run a parser, and restore the pre-parse state if it fails.
	fn read_atomically<T, F>(&mut self, inner: F) -> Option<T>
	where
	F: FnOnce(&mut Parser<'_>) -> Option<T>,
	{
	let state = self.state;
	let result = inner(self);
	if result.is_none() {
	self.state = state;
	}
	result
	}

	/// Run a parser, but fail if the entire input wasn't consumed.
	/// Doesn't run atomically.
	fn parse_with<T, F>(&mut self, inner: F, kind: AddrKind) -> Result<T, AddrParseError>
	where
	F: FnOnce(&mut Parser<'_>) -> Option<T>,
	{
	let result = inner(self);
	if self.state.is_empty() { result } else { None }.ok_or(AddrParseError(kind))
	}

	/// Peek the next character from the input
	fn peek_char(&self) -> Option<char> {
	self.state.first().map(\|&b\| char::from(b))
	}

	/// Read the next character from the input
	fn read_char(&mut self) -> Option<char> {
	self.state.split_first().map(\|(&b, tail)\| {
	self.state = tail;
	char::from(b)
	})
	}

	#[must_use]
	/// Read the next character from the input if it matches the target.
	fn read_given_char(&mut self, target: char) -> Option<()> {
	self.read_atomically(\|p\| {
	p.read_char().and_then(\|c\| if c == target { Some(()) } else { None })
	})
	}

	/// Helper for reading separators in an indexed loop. Reads the separator
	/// character iff index > 0, then runs the parser. When used in a loop,
	/// the separator character will only be read on index > 0 (see
	/// read_ipv4_addr for an example)
	fn read_separator<T, F>(&mut self, sep: char, index: usize, inner: F) -> Option<T>
	where
	F: FnOnce(&mut Parser<'_>) -> Option<T>,
	{
	self.read_atomically(move \|p\| {
	if index > 0 {
	p.read_given_char(sep)?;
	}
	inner(p)
	})
	}

	// Read a number off the front of the input in the given radix, stopping
	// at the first non-digit character or eof. Fails if the number has more
	// digits than max_digits or if there is no number.
	fn read_number<T: ReadNumberHelper>(
	&mut self,
	radix: u32,
	max_digits: Option<usize>,
	allow_zero_prefix: bool,
	) -> Option<T> {
	self.read_atomically(move \|p\| {
	let mut result = T::ZERO;
	let mut digit_count = 0;
	let has_leading_zero = p.peek_char() == Some('0');

	while let Some(digit) = p.read_atomically(\|p\| p.read_char()?.to_digit(radix)) {
	result = result.checked_mul(radix)?;
	result = result.checked_add(digit)?;
	digit_count += 1;
	if let Some(max_digits) = max_digits {
	if digit_count > max_digits {
	return None;
	}
	}
	}

	if digit_count == 0 {
	None
	} else if !allow_zero_prefix && has_leading_zero && digit_count > 1 {
	None
	} else {
	Some(result)
	}
	})
	}

	/// Read an IPv4 address.
	fn read_ipv4_addr(&mut self) -> Option<Ipv4Addr> {
	self.read_atomically(\|p\| {
	let mut groups = [0; 4];

	for (i, slot) in groups.iter_mut().enumerate() {
	*slot = p.read_separator('.', i, \|p\| {
	// Disallow octal number in IP string.
	// https://tools.ietf.org/html/rfc6943#section-3.1.1
	p.read_number(10, Some(3), false)
	})?;
	}

	Some(groups.into())
	})
	}

	/// Read an IPv6 Address.
	fn read_ipv6_addr(&mut self) -> Option<Ipv6Addr> {
	/// Read a chunk of an IPv6 address into `groups`. Returns the number
	/// of groups read, along with a bool indicating if an embedded
	/// trailing IPv4 address was read. Specifically, read a series of
	/// colon-separated IPv6 groups (0x0000 - 0xFFFF), with an optional
	/// trailing embedded IPv4 address.
	fn read_groups(p: &mut Parser<'_>, groups: &mut [u16]) -> (usize, bool) {
	let limit = groups.len();

	for (i, slot) in groups.iter_mut().enumerate() {
	// Try to read a trailing embedded IPv4 address. There must be
	// at least two groups left.
	if i < limit - 1 {
	let ipv4 = p.read_separator(':', i, \|p\| p.read_ipv4_addr());

	if let Some(v4_addr) = ipv4 {
	let [one, two, three, four] = v4_addr.octets();
	groups[i + 0] = u16::from_be_bytes([one, two]);
	groups[i + 1] = u16::from_be_bytes([three, four]);
	return (i + 2, true);
	}
	}

	let group = p.read_separator(':', i, \|p\| p.read_number(16, Some(4), true));

	match group {
	Some(g) => *slot = g,
	None => return (i, false),
	}
	}
	(groups.len(), false)
	}

	self.read_atomically(\|p\| {
	// Read the front part of the address; either the whole thing, or up
	// to the first ::
	let mut head = [0; 8];
	let (head_size, head_ipv4) = read_groups(p, &mut head);

	if head_size == 8 {
	return Some(head.into());
	}

	// IPv4 part is not allowed before `::`
	if head_ipv4 {
	return None;
	}

	// Read `::` if previous code parsed less than 8 groups.
	// `::` indicates one or more groups of 16 bits of zeros.
	p.read_given_char(':')?;
	p.read_given_char(':')?;

	// Read the back part of the address. The :: must contain at least one
	// set of zeroes, so our max length is 7.
	let mut tail = [0; 7];
	let limit = 8 - (head_size + 1);
	let (tail_size, _) = read_groups(p, &mut tail[..limit]);

	// Concat the head and tail of the IP address
	head[(8 - tail_size)..8].copy_from_slice(&tail[..tail_size]);

	Some(head.into())
	})
	}

	/// Read an IP Address, either IPv4 or IPv6.
	fn read_ip_addr(&mut self) -> Option<IpAddr> {
	self.read_ipv4_addr().map(IpAddr::V4).or_else(move \|\| self.read_ipv6_addr().map(IpAddr::V6))
	}

	/// Read a `:` followed by a port in base 10.
	fn read_port(&mut self) -> Option<u16> {
	self.read_atomically(\|p\| {
	p.read_given_char(':')?;
	p.read_number(10, None, true)
	})
	}

	/// Read a `%` followed by a scope ID in base 10.
	fn read_scope_id(&mut self) -> Option<u32> {
	self.read_atomically(\|p\| {
	p.read_given_char('%')?;
	p.read_number(10, None, true)
	})
	}

	/// Read an IPv4 address with a port.
	fn read_socket_addr_v4(&mut self) -> Option<SocketAddrV4> {
	self.read_atomically(\|p\| {
	let ip = p.read_ipv4_addr()?;
	let port = p.read_port()?;
	Some(SocketAddrV4::new(ip, port))
	})
	}

	/// Read an IPv6 address with a port.
	fn read_socket_addr_v6(&mut self) -> Option<SocketAddrV6> {
	self.read_atomically(\|p\| {
	p.read_given_char('[')?;
	let ip = p.read_ipv6_addr()?;
	let scope_id = p.read_scope_id().unwrap_or(0);
	p.read_given_char(']')?;

	let port = p.read_port()?;
	Some(SocketAddrV6::new(ip, port, 0, scope_id))
	})
	}

	/// Read an IP address with a port
	fn read_socket_addr(&mut self) -> Option<SocketAddr> {
	self.read_socket_addr_v4()
	.map(SocketAddr::V4)
	.or_else(\|\| self.read_socket_addr_v6().map(SocketAddr::V6))
	}
	}

	impl IpAddr {
	/// Parse an IP address from a slice of bytes.
	///
	/// ```
	/// #![feature(addr_parse_ascii)]
	///
	/// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
	///
	/// let localhost_v4 = IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1));
	/// let localhost_v6 = IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1));
	///
	/// assert_eq!(IpAddr::parse_ascii(b"127.0.0.1"), Ok(localhost_v4));
	/// assert_eq!(IpAddr::parse_ascii(b"::1"), Ok(localhost_v6));
	/// ```
	#[unstable(feature = "addr_parse_ascii", issue = "101035")]
	pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
	Parser::new(b).parse_with(\|p\| p.read_ip_addr(), AddrKind::Ip)
	}
	}

	#[stable(feature = "ip_addr", since = "1.7.0")]
	impl FromStr for IpAddr {
	type Err = AddrParseError;
	fn from_str(s: &str) -> Result<IpAddr, AddrParseError> {
	Self::parse_ascii(s.as_bytes())
	}
	}

	impl Ipv4Addr {
	/// Parse an IPv4 address from a slice of bytes.
	///
	/// ```
	/// #![feature(addr_parse_ascii)]
	///
	/// use std::net::Ipv4Addr;
	///
	/// let localhost = Ipv4Addr::new(127, 0, 0, 1);
	///
	/// assert_eq!(Ipv4Addr::parse_ascii(b"127.0.0.1"), Ok(localhost));
	/// ```
	#[unstable(feature = "addr_parse_ascii", issue = "101035")]
	pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
	// don't try to parse if too long
	if b.len() > 15 {
	Err(AddrParseError(AddrKind::Ipv4))
	} else {
	Parser::new(b).parse_with(\|p\| p.read_ipv4_addr(), AddrKind::Ipv4)
	}
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl FromStr for Ipv4Addr {
	type Err = AddrParseError;
	fn from_str(s: &str) -> Result<Ipv4Addr, AddrParseError> {
	Self::parse_ascii(s.as_bytes())
	}
	}

	impl Ipv6Addr {
	/// Parse an IPv6 address from a slice of bytes.
	///
	/// ```
	/// #![feature(addr_parse_ascii)]
	///
	/// use std::net::Ipv6Addr;
	///
	/// let localhost = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1);
	///
	/// assert_eq!(Ipv6Addr::parse_ascii(b"::1"), Ok(localhost));
	/// ```
	#[unstable(feature = "addr_parse_ascii", issue = "101035")]
	pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
	Parser::new(b).parse_with(\|p\| p.read_ipv6_addr(), AddrKind::Ipv6)
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl FromStr for Ipv6Addr {
	type Err = AddrParseError;
	fn from_str(s: &str) -> Result<Ipv6Addr, AddrParseError> {
	Self::parse_ascii(s.as_bytes())
	}
	}

	impl SocketAddrV4 {
	/// Parse an IPv4 socket address from a slice of bytes.
	///
	/// ```
	/// #![feature(addr_parse_ascii)]
	///
	/// use std::net::{Ipv4Addr, SocketAddrV4};
	///
	/// let socket = SocketAddrV4::new(Ipv4Addr::new(127, 0, 0, 1), 8080);
	///
	/// assert_eq!(SocketAddrV4::parse_ascii(b"127.0.0.1:8080"), Ok(socket));
	/// ```
	#[unstable(feature = "addr_parse_ascii", issue = "101035")]
	pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
	Parser::new(b).parse_with(\|p\| p.read_socket_addr_v4(), AddrKind::SocketV4)
	}
	}

	#[stable(feature = "socket_addr_from_str", since = "1.5.0")]
	impl FromStr for SocketAddrV4 {
	type Err = AddrParseError;
	fn from_str(s: &str) -> Result<SocketAddrV4, AddrParseError> {
	Self::parse_ascii(s.as_bytes())
	}
	}

	impl SocketAddrV6 {
	/// Parse an IPv6 socket address from a slice of bytes.
	///
	/// ```
	/// #![feature(addr_parse_ascii)]
	///
	/// use std::net::{Ipv6Addr, SocketAddrV6};
	///
	/// let socket = SocketAddrV6::new(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 1), 8080, 0, 0);
	///
	/// assert_eq!(SocketAddrV6::parse_ascii(b"[2001:db8::1]:8080"), Ok(socket));
	/// ```
	#[unstable(feature = "addr_parse_ascii", issue = "101035")]
	pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
	Parser::new(b).parse_with(\|p\| p.read_socket_addr_v6(), AddrKind::SocketV6)
	}
	}

	#[stable(feature = "socket_addr_from_str", since = "1.5.0")]
	impl FromStr for SocketAddrV6 {
	type Err = AddrParseError;
	fn from_str(s: &str) -> Result<SocketAddrV6, AddrParseError> {
	Self::parse_ascii(s.as_bytes())
	}
	}

	impl SocketAddr {
	/// Parse a socket address from a slice of bytes.
	///
	/// ```
	/// #![feature(addr_parse_ascii)]
	///
	/// use std::net::{IpAddr, Ipv4Addr, Ipv6Addr, SocketAddr};
	///
	/// let socket_v4 = SocketAddr::new(IpAddr::V4(Ipv4Addr::new(127, 0, 0, 1)), 8080);
	/// let socket_v6 = SocketAddr::new(IpAddr::V6(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1)), 8080);
	///
	/// assert_eq!(SocketAddr::parse_ascii(b"127.0.0.1:8080"), Ok(socket_v4));
	/// assert_eq!(SocketAddr::parse_ascii(b"[::1]:8080"), Ok(socket_v6));
	/// ```
	#[unstable(feature = "addr_parse_ascii", issue = "101035")]
	pub fn parse_ascii(b: &[u8]) -> Result<Self, AddrParseError> {
	Parser::new(b).parse_with(\|p\| p.read_socket_addr(), AddrKind::Socket)
	}
	}

	#[stable(feature = "rust1", since = "1.0.0")]
	impl FromStr for SocketAddr {
	type Err = AddrParseError;
	fn from_str(s: &str) -> Result<SocketAddr, AddrParseError> {
	Self::parse_ascii(s.as_bytes())
	}
	}

	#[derive(Debug, Clone, PartialEq, Eq)]
	enum AddrKind {
	Ip,
	Ipv4,
	Ipv6,
	Socket,
	SocketV4,
	SocketV6,
	}

	/// An error which can be returned when parsing an IP address or a socket address.
	///
	/// This error is used as the error type for the [`FromStr`] implementation for
	/// [`IpAddr`], [`Ipv4Addr`], [`Ipv6Addr`], [`SocketAddr`], [`SocketAddrV4`], and
	/// [`SocketAddrV6`].
	///
	/// # Potential causes
	///
	/// `AddrParseError` may be thrown because the provided string does not parse as the given type,
	/// often because it includes information only handled by a different address type.
	///
	/// ```should_panic
	/// use std::net::IpAddr;
	/// let _foo: IpAddr = "127.0.0.1:8080".parse().expect("Cannot handle the socket port");
	/// ```
	///
	/// [`IpAddr`] doesn't handle the port. Use [`SocketAddr`] instead.
	///
	/// ```
	/// use std::net::SocketAddr;
	///
	/// // No problem, the `panic!` message has disappeared.
	/// let _foo: SocketAddr = "127.0.0.1:8080".parse().expect("unreachable panic");
	/// ```
	#[stable(feature = "rust1", since = "1.0.0")]
	#[derive(Debug, Clone, PartialEq, Eq)]
	pub struct AddrParseError(AddrKind);

	#[stable(feature = "addr_parse_error_error", since = "1.4.0")]
	impl fmt::Display for AddrParseError {
	#[allow(deprecated, deprecated_in_future)]
	fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
	fmt.write_str(self.description())
	}
	}

	#[stable(feature = "addr_parse_error_error", since = "1.4.0")]
	impl Error for AddrParseError {
	#[allow(deprecated)]
	fn description(&self) -> &str {
	match self.0 {
	AddrKind::Ip => "invalid IP address syntax",
	AddrKind::Ipv4 => "invalid IPv4 address syntax",
	AddrKind::Ipv6 => "invalid IPv6 address syntax",
	AddrKind::Socket => "invalid socket address syntax",
	AddrKind::SocketV4 => "invalid IPv4 socket address syntax",
	AddrKind::SocketV6 => "invalid IPv6 socket address syntax",
	}
	}
	}