vendor/url-1.7.2/src/host.rs - toolchain/rustc - Git at Google

 // Copyright 2013-2016 The rust-url developers.
 //
 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.

 #[cfg(feature = "heapsize")] use heapsize::HeapSizeOf;
 use std::cmp;
 use std::fmt::{self, Formatter};
 use std::io;
 use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
 use std::vec;
 use parser::{ParseResult, ParseError};
 use percent_encoding::{percent_decode, utf8_percent_encode, SIMPLE_ENCODE_SET};
 use idna;

 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 pub enum HostInternal {
     None,
     Domain,
     Ipv4(Ipv4Addr),
     Ipv6(Ipv6Addr),
 }

 #[cfg(feature = "heapsize")]
 known_heap_size!(0, HostInternal);

 #[cfg(feature="serde")]
 impl ::serde::Serialize for HostInternal {
     fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error> where S: ::serde::Serializer {
         // This doesn’t use `derive` because that involves
         // large dependencies (that take a long time to build), and
         // either Macros 1.1 which are not stable yet or a cumbersome build script.
         //
         // Implementing `Serializer` correctly for an enum is tricky,
         // so let’s use existing enums that already do.
         use std::net::IpAddr;
         match *self {
             HostInternal::None => None,
             HostInternal::Domain => Some(None),
             HostInternal::Ipv4(addr) => Some(Some(IpAddr::V4(addr))),
             HostInternal::Ipv6(addr) => Some(Some(IpAddr::V6(addr))),
         }.serialize(serializer)
     }
 }

 #[cfg(feature="serde")]
 impl ::serde::Deserialize for HostInternal {
     fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error> where D: ::serde::Deserializer {
         use std::net::IpAddr;
         Ok(match ::serde::Deserialize::deserialize(deserializer)? {
             None => HostInternal::None,
             Some(None) => HostInternal::Domain,
             Some(Some(IpAddr::V4(addr))) => HostInternal::Ipv4(addr),
             Some(Some(IpAddr::V6(addr))) => HostInternal::Ipv6(addr),
         })
     }
 }

 impl<S> From<Host<S>> for HostInternal {
     fn from(host: Host<S>) -> HostInternal {
         match host {
             Host::Domain(_) => HostInternal::Domain,
             Host::Ipv4(address) => HostInternal::Ipv4(address),
             Host::Ipv6(address) => HostInternal::Ipv6(address),
         }
     }
 }

 /// The host name of an URL.
 #[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
 pub enum Host<S=String> {
     /// A DNS domain name, as '.' dot-separated labels.
     /// Non-ASCII labels are encoded in punycode per IDNA if this is the host of
     /// a special URL, or percent encoded for non-special URLs. Hosts for
     /// non-special URLs are also called opaque hosts.
     Domain(S),

     /// An IPv4 address.
     /// `Url::host_str` returns the serialization of this address,
     /// as four decimal integers separated by `.` dots.
     Ipv4(Ipv4Addr),

     /// An IPv6 address.
     /// `Url::host_str` returns the serialization of that address between `[` and `]` brackets,
     /// in the format per [RFC 5952 *A Recommendation
     /// for IPv6 Address Text Representation*](https://tools.ietf.org/html/rfc5952):
     /// lowercase hexadecimal with maximal `::` compression.
     Ipv6(Ipv6Addr),
 }

 #[cfg(feature="serde")]
 impl<S: ::serde::Serialize>  ::serde::Serialize for Host<S> {
     fn serialize<R>(&self, serializer: &mut R) -> Result<(), R::Error> where R: ::serde::Serializer {
         use std::net::IpAddr;
         match *self {
             Host::Domain(ref s) => Ok(s),
             Host::Ipv4(addr) => Err(IpAddr::V4(addr)),
             Host::Ipv6(addr) => Err(IpAddr::V6(addr)),
         }.serialize(serializer)
     }
 }

 #[cfg(feature="serde")]
 impl<S: ::serde::Deserialize> ::serde::Deserialize for Host<S> {
     fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error> where D: ::serde::Deserializer {
         use std::net::IpAddr;
         Ok(match ::serde::Deserialize::deserialize(deserializer)? {
             Ok(s) => Host::Domain(s),
             Err(IpAddr::V4(addr)) => Host::Ipv4(addr),
             Err(IpAddr::V6(addr)) => Host::Ipv6(addr),
         })
     }
 }

 #[cfg(feature = "heapsize")]
 impl<S: HeapSizeOf> HeapSizeOf for Host<S> {
     fn heap_size_of_children(&self) -> usize {
         match *self {
             Host::Domain(ref s) => s.heap_size_of_children(),
             _ => 0,
         }
     }
 }

 impl<'a> Host<&'a str> {
     /// Return a copy of `self` that owns an allocated `String` but does not borrow an `&Url`.
     pub fn to_owned(&self) -> Host<String> {
         match *self {
             Host::Domain(domain) => Host::Domain(domain.to_owned()),
             Host::Ipv4(address) => Host::Ipv4(address),
             Host::Ipv6(address) => Host::Ipv6(address),
         }
     }
 }

 impl Host<String> {
     /// Parse a host: either an IPv6 address in [] square brackets, or a domain.
     ///
     /// <https://url.spec.whatwg.org/#host-parsing>
     pub fn parse(input: &str) -> Result<Self, ParseError> {
         if input.starts_with('[') {
             if !input.ends_with(']') {
                 return Err(ParseError::InvalidIpv6Address)
             }
             return parse_ipv6addr(&input[1..input.len() - 1]).map(Host::Ipv6)
         }
         let domain = percent_decode(input.as_bytes()).decode_utf8_lossy();
         let domain = idna::domain_to_ascii(&domain)?;
         if domain.find(|c| matches!(c,
             '\0' | '\t' | '\n' | '\r' | ' ' | '#' | '%' | '/' | ':' | '?' | '@' | '[' | '\\' | ']'
         )).is_some() {
             return Err(ParseError::InvalidDomainCharacter)
         }
         if let Some(address) = parse_ipv4addr(&domain)? {
             Ok(Host::Ipv4(address))
         } else {
             Ok(Host::Domain(domain.into()))
         }
     }

     // <https://url.spec.whatwg.org/#concept-opaque-host-parser>
     pub fn parse_opaque(input: &str) -> Result<Self, ParseError> {
         if input.starts_with('[') {
             if !input.ends_with(']') {
                 return Err(ParseError::InvalidIpv6Address)
             }
             return parse_ipv6addr(&input[1..input.len() - 1]).map(Host::Ipv6)
         }
         if input.find(|c| matches!(c,
             '\0' | '\t' | '\n' | '\r' | ' ' | '#' | '/' | ':' | '?' | '@' | '[' | '\\' | ']'
         )).is_some() {
             return Err(ParseError::InvalidDomainCharacter)
         }
         let s = utf8_percent_encode(input, SIMPLE_ENCODE_SET).to_string();
         Ok(Host::Domain(s))
     }
 }

 impl<S: AsRef<str>> fmt::Display for Host<S> {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         match *self {
             Host::Domain(ref domain) => domain.as_ref().fmt(f),
             Host::Ipv4(ref addr) => addr.fmt(f),
             Host::Ipv6(ref addr) => {
                 f.write_str("[")?;
                 write_ipv6(addr, f)?;
                 f.write_str("]")
             }
         }
     }
 }

 /// This mostly exists because coherence rules don’t allow us to implement
 /// `ToSocketAddrs for (Host<S>, u16)`.
 #[derive(Clone, Debug)]
 pub struct HostAndPort<S=String> {
     pub host: Host<S>,
     pub port: u16,
 }

 impl<'a> HostAndPort<&'a str> {
     /// Return a copy of `self` that owns an allocated `String` but does not borrow an `&Url`.
     pub fn to_owned(&self) -> HostAndPort<String> {
         HostAndPort {
             host: self.host.to_owned(),
             port: self.port
         }
     }
 }

 impl<S: AsRef<str>> fmt::Display for HostAndPort<S> {
     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
         self.host.fmt(f)?;
         f.write_str(":")?;
         self.port.fmt(f)
     }
 }


 impl<S: AsRef<str>> ToSocketAddrs for HostAndPort<S> {
     type Iter = SocketAddrs;

     fn to_socket_addrs(&self) -> io::Result<Self::Iter> {
         let port = self.port;
         match self.host {
             Host::Domain(ref domain) => Ok(SocketAddrs {
                 // FIXME: use std::net::lookup_host when it’s stable.
                 state: SocketAddrsState::Domain((domain.as_ref(), port).to_socket_addrs()?)
             }),
             Host::Ipv4(address) => Ok(SocketAddrs {
                 state: SocketAddrsState::One(SocketAddr::V4(SocketAddrV4::new(address, port)))
             }),
             Host::Ipv6(address) => Ok(SocketAddrs {
                 state: SocketAddrsState::One(SocketAddr::V6(SocketAddrV6::new(address, port, 0, 0)))
             }),
         }
     }
 }

 /// Socket addresses for an URL.
 #[derive(Debug)]
 pub struct SocketAddrs {
     state: SocketAddrsState
 }

 #[derive(Debug)]
 enum SocketAddrsState {
     Domain(vec::IntoIter<SocketAddr>),
     One(SocketAddr),
     Done,
 }

 impl Iterator for SocketAddrs {
     type Item = SocketAddr;
     fn next(&mut self) -> Option<SocketAddr> {
         match self.state {
             SocketAddrsState::Domain(ref mut iter) => iter.next(),
             SocketAddrsState::One(s) => {
                 self.state = SocketAddrsState::Done;
                 Some(s)
             }
             SocketAddrsState::Done => None
         }
     }
 }

 fn write_ipv6(addr: &Ipv6Addr, f: &mut Formatter) -> fmt::Result {
     let segments = addr.segments();
     let (compress_start, compress_end) = longest_zero_sequence(&segments);
     let mut i = 0;
     while i < 8 {
         if i == compress_start {
             f.write_str(":")?;
             if i == 0 {
                 f.write_str(":")?;
             }
             if compress_end < 8 {
                 i = compress_end;
             } else {
                 break;
             }
         }
         write!(f, "{:x}", segments[i as usize])?;
         if i < 7 {
             f.write_str(":")?;
         }
         i += 1;
     }
     Ok(())
 }

 // https://url.spec.whatwg.org/#concept-ipv6-serializer step 2 and 3
 fn longest_zero_sequence(pieces: &[u16; 8]) -> (isize, isize) {
     let mut longest = -1;
     let mut longest_length = -1;
     let mut start = -1;
     macro_rules! finish_sequence(
         ($end: expr) => {
             if start >= 0 {
                 let length = $end - start;
                 if length > longest_length {
                     longest = start;
                     longest_length = length;
                 }
             }
         };
     );
     for i in 0..8 {
         if pieces[i as usize] == 0 {
             if start < 0 {
                 start = i;
             }
         } else {
             finish_sequence!(i);
             start = -1;
         }
     }
     finish_sequence!(8);
     // https://url.spec.whatwg.org/#concept-ipv6-serializer
     // step 3: ignore lone zeroes
     if longest_length < 2 {
         (-1, -2)
     } else {
         (longest, longest + longest_length)
     }
 }

 /// <https://url.spec.whatwg.org/#ipv4-number-parser>
 fn parse_ipv4number(mut input: &str) -> Result<Option<u32>, ()> {
     let mut r = 10;
     if input.starts_with("0x") || input.starts_with("0X") {
         input = &input[2..];
         r = 16;
     } else if input.len() >= 2 && input.starts_with('0') {
         input = &input[1..];
         r = 8;
     }

     // At the moment we can't know the reason why from_str_radix fails
     // https://github.com/rust-lang/rust/issues/22639
     // So instead we check if the input looks like a real number and only return
     // an error when it's an overflow.
     let valid_number = match r {
         8 => input.chars().all(|c| c >= '0' && c <='7'),
         10 => input.chars().all(|c| c >= '0' && c <='9'),
         16 => input.chars().all(|c| (c >= '0' && c <='9') || (c >='a' && c <= 'f') || (c >= 'A' && c <= 'F')),
         _ => false
     };

     if !valid_number {
         return Ok(None);
     }

     if input.is_empty() {
         return Ok(Some(0));
     }
     if input.starts_with('+') {
         return Ok(None);
     }
     match u32::from_str_radix(input, r) {
         Ok(number) => Ok(Some(number)),
         Err(_) => Err(()),
     }
 }

 /// <https://url.spec.whatwg.org/#concept-ipv4-parser>
 fn parse_ipv4addr(input: &str) -> ParseResult<Option<Ipv4Addr>> {
     if input.is_empty() {
         return Ok(None)
     }
     let mut parts: Vec<&str> = input.split('.').collect();
     if parts.last() == Some(&"") {
         parts.pop();
     }
     if parts.len() > 4 {
         return Ok(None);
     }
     let mut numbers: Vec<u32> = Vec::new();
     let mut overflow = false;
     for part in parts {
         if part == "" {
             return Ok(None);
         }
         match parse_ipv4number(part) {
             Ok(Some(n)) => numbers.push(n),
             Ok(None) => return Ok(None),
             Err(()) => overflow = true
         };
     }
     if overflow {
         return Err(ParseError::InvalidIpv4Address);
     }
     let mut ipv4 = numbers.pop().expect("a non-empty list of numbers");
     // Equivalent to: ipv4 >= 256 ** (4 − numbers.len())
     if ipv4 > u32::max_value() >> (8 * numbers.len() as u32)  {
         return Err(ParseError::InvalidIpv4Address);
     }
     if numbers.iter().any(|x| *x > 255) {
         return Err(ParseError::InvalidIpv4Address);
     }
     for (counter, n) in numbers.iter().enumerate() {
         ipv4 += n << (8 * (3 - counter as u32))
     }
     Ok(Some(Ipv4Addr::from(ipv4)))
 }

 /// <https://url.spec.whatwg.org/#concept-ipv6-parser>
 fn parse_ipv6addr(input: &str) -> ParseResult<Ipv6Addr> {
     let input = input.as_bytes();
     let len = input.len();
     let mut is_ip_v4 = false;
     let mut pieces = [0, 0, 0, 0, 0, 0, 0, 0];
     let mut piece_pointer = 0;
     let mut compress_pointer = None;
     let mut i = 0;

     if len < 2 {
         return Err(ParseError::InvalidIpv6Address)
     }

     if input[0] == b':' {
         if input[1] != b':' {
             return Err(ParseError::InvalidIpv6Address)
         }
         i = 2;
         piece_pointer = 1;
         compress_pointer = Some(1);
     }

     while i < len {
         if piece_pointer == 8 {
             return Err(ParseError::InvalidIpv6Address)
         }
         if input[i] == b':' {
             if compress_pointer.is_some() {
                 return Err(ParseError::InvalidIpv6Address)
             }
             i += 1;
             piece_pointer += 1;
             compress_pointer = Some(piece_pointer);
             continue
         }
         let start = i;
         let end = cmp::min(len, start + 4);
         let mut value = 0u16;
         while i < end {
             match (input[i] as char).to_digit(16) {
                 Some(digit) => {
                     value = value * 0x10 + digit as u16;
                     i += 1;
                 },
                 None => break
             }
         }
         if i < len {
             match input[i] {
                 b'.' => {
                     if i == start {
                         return Err(ParseError::InvalidIpv6Address)
                     }
                     i = start;
                     if piece_pointer > 6 {
                         return Err(ParseError::InvalidIpv6Address)
                     }
                     is_ip_v4 = true;
                 },
                 b':' => {
                     i += 1;
                     if i == len {
                         return Err(ParseError::InvalidIpv6Address)
                     }
                 },
                 _ => return Err(ParseError::InvalidIpv6Address)
             }
         }
         if is_ip_v4 {
             break
         }
         pieces[piece_pointer] = value;
         piece_pointer += 1;
     }

     if is_ip_v4 {
         if piece_pointer > 6 {
             return Err(ParseError::InvalidIpv6Address)
         }
         let mut numbers_seen = 0;
         while i < len {
             if numbers_seen > 0 {
                 if numbers_seen < 4 && (i < len && input[i] == b'.') {
                     i += 1
                 } else {
                     return Err(ParseError::InvalidIpv6Address)
                 }
             }

             let mut ipv4_piece = None;
             while i < len {
                 let digit = match input[i] {
                     c @ b'0' ... b'9' => c - b'0',
                     _ => break
                 };
                 match ipv4_piece {
                     None => ipv4_piece = Some(digit as u16),
                     Some(0) => return Err(ParseError::InvalidIpv6Address),  // No leading zero
                     Some(ref mut v) => {
                         *v = *v * 10 + digit as u16;
                         if *v > 255 {
                             return Err(ParseError::InvalidIpv6Address)
                         }
                     }
                 }
                 i += 1;
             }

             pieces[piece_pointer] = if let Some(v) = ipv4_piece {
                 pieces[piece_pointer] * 0x100 + v
             } else {
                 return Err(ParseError::InvalidIpv6Address)
             };
             numbers_seen += 1;

             if numbers_seen == 2 || numbers_seen == 4 {
                 piece_pointer += 1;
             }
         }

         if numbers_seen != 4 {
             return Err(ParseError::InvalidIpv6Address)
         }
     }

     if i < len {
         return Err(ParseError::InvalidIpv6Address)
     }

     match compress_pointer {
         Some(compress_pointer) => {
             let mut swaps = piece_pointer - compress_pointer;
             piece_pointer = 7;
             while swaps > 0 {
                 pieces.swap(piece_pointer, compress_pointer + swaps - 1);
                 swaps -= 1;
                 piece_pointer -= 1;
             }
         }
         _ => if piece_pointer != 8 {
             return Err(ParseError::InvalidIpv6Address)
         }
     }
     Ok(Ipv6Addr::new(pieces[0], pieces[1], pieces[2], pieces[3],
                      pieces[4], pieces[5], pieces[6], pieces[7]))
 }
	// Copyright 2013-2016 The rust-url developers.
	//
	// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
	// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
	// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
	// option. This file may not be copied, modified, or distributed
	// except according to those terms.

	#[cfg(feature = "heapsize")] use heapsize::HeapSizeOf;
	use std::cmp;
	use std::fmt::{self, Formatter};
	use std::io;
	use std::net::{Ipv4Addr, Ipv6Addr, SocketAddr, SocketAddrV4, SocketAddrV6, ToSocketAddrs};
	use std::vec;
	use parser::{ParseResult, ParseError};
	use percent_encoding::{percent_decode, utf8_percent_encode, SIMPLE_ENCODE_SET};
	use idna;

	#[derive(Copy, Clone, Debug, Eq, PartialEq)]
	pub enum HostInternal {
	None,
	Domain,
	Ipv4(Ipv4Addr),
	Ipv6(Ipv6Addr),
	}

	#[cfg(feature = "heapsize")]
	known_heap_size!(0, HostInternal);

	#[cfg(feature="serde")]
	impl ::serde::Serialize for HostInternal {
	fn serialize<S>(&self, serializer: &mut S) -> Result<(), S::Error> where S: ::serde::Serializer {
	// This doesn’t use `derive` because that involves
	// large dependencies (that take a long time to build), and
	// either Macros 1.1 which are not stable yet or a cumbersome build script.
	//
	// Implementing `Serializer` correctly for an enum is tricky,
	// so let’s use existing enums that already do.
	use std::net::IpAddr;
	match *self {
	HostInternal::None => None,
	HostInternal::Domain => Some(None),
	HostInternal::Ipv4(addr) => Some(Some(IpAddr::V4(addr))),
	HostInternal::Ipv6(addr) => Some(Some(IpAddr::V6(addr))),
	}.serialize(serializer)
	}
	}

	#[cfg(feature="serde")]
	impl ::serde::Deserialize for HostInternal {
	fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error> where D: ::serde::Deserializer {
	use std::net::IpAddr;
	Ok(match ::serde::Deserialize::deserialize(deserializer)? {
	None => HostInternal::None,
	Some(None) => HostInternal::Domain,
	Some(Some(IpAddr::V4(addr))) => HostInternal::Ipv4(addr),
	Some(Some(IpAddr::V6(addr))) => HostInternal::Ipv6(addr),
	})
	}
	}

	impl<S> From<Host<S>> for HostInternal {
	fn from(host: Host<S>) -> HostInternal {
	match host {
	Host::Domain(_) => HostInternal::Domain,
	Host::Ipv4(address) => HostInternal::Ipv4(address),
	Host::Ipv6(address) => HostInternal::Ipv6(address),
	}
	}
	}

	/// The host name of an URL.
	#[derive(Clone, Debug, Eq, PartialEq, Ord, PartialOrd, Hash)]
	pub enum Host<S=String> {
	/// A DNS domain name, as '.' dot-separated labels.
	/// Non-ASCII labels are encoded in punycode per IDNA if this is the host of
	/// a special URL, or percent encoded for non-special URLs. Hosts for
	/// non-special URLs are also called opaque hosts.
	Domain(S),

	/// An IPv4 address.
	/// `Url::host_str` returns the serialization of this address,
	/// as four decimal integers separated by `.` dots.
	Ipv4(Ipv4Addr),

	/// An IPv6 address.
	/// `Url::host_str` returns the serialization of that address between `[` and `]` brackets,
	/// in the format per [RFC 5952 *A Recommendation
	/// for IPv6 Address Text Representation*](https://tools.ietf.org/html/rfc5952):
	/// lowercase hexadecimal with maximal `::` compression.
	Ipv6(Ipv6Addr),
	}

	#[cfg(feature="serde")]
	impl<S: ::serde::Serialize> ::serde::Serialize for Host<S> {
	fn serialize<R>(&self, serializer: &mut R) -> Result<(), R::Error> where R: ::serde::Serializer {
	use std::net::IpAddr;
	match *self {
	Host::Domain(ref s) => Ok(s),
	Host::Ipv4(addr) => Err(IpAddr::V4(addr)),
	Host::Ipv6(addr) => Err(IpAddr::V6(addr)),
	}.serialize(serializer)
	}
	}

	#[cfg(feature="serde")]
	impl<S: ::serde::Deserialize> ::serde::Deserialize for Host<S> {
	fn deserialize<D>(deserializer: &mut D) -> Result<Self, D::Error> where D: ::serde::Deserializer {
	use std::net::IpAddr;
	Ok(match ::serde::Deserialize::deserialize(deserializer)? {
	Ok(s) => Host::Domain(s),
	Err(IpAddr::V4(addr)) => Host::Ipv4(addr),
	Err(IpAddr::V6(addr)) => Host::Ipv6(addr),
	})
	}
	}

	#[cfg(feature = "heapsize")]
	impl<S: HeapSizeOf> HeapSizeOf for Host<S> {
	fn heap_size_of_children(&self) -> usize {
	match *self {
	Host::Domain(ref s) => s.heap_size_of_children(),
	_ => 0,
	}
	}
	}

	impl<'a> Host<&'a str> {
	/// Return a copy of `self` that owns an allocated `String` but does not borrow an `&Url`.
	pub fn to_owned(&self) -> Host<String> {
	match *self {
	Host::Domain(domain) => Host::Domain(domain.to_owned()),
	Host::Ipv4(address) => Host::Ipv4(address),
	Host::Ipv6(address) => Host::Ipv6(address),
	}
	}
	}

	impl Host<String> {
	/// Parse a host: either an IPv6 address in [] square brackets, or a domain.
	///
	/// <https://url.spec.whatwg.org/#host-parsing>
	pub fn parse(input: &str) -> Result<Self, ParseError> {
	if input.starts_with('[') {
	if !input.ends_with(']') {
	return Err(ParseError::InvalidIpv6Address)
	}
	return parse_ipv6addr(&input[1..input.len() - 1]).map(Host::Ipv6)
	}
	let domain = percent_decode(input.as_bytes()).decode_utf8_lossy();
	let domain = idna::domain_to_ascii(&domain)?;
	if domain.find(\|c\| matches!(c,
	'\0' \| '\t' \| '\n' \| '\r' \| ' ' \| '#' \| '%' \| '/' \| ':' \| '?' \| '@' \| '[' \| '\\' \| ']'
	)).is_some() {
	return Err(ParseError::InvalidDomainCharacter)
	}
	if let Some(address) = parse_ipv4addr(&domain)? {
	Ok(Host::Ipv4(address))
	} else {
	Ok(Host::Domain(domain.into()))
	}
	}

	// <https://url.spec.whatwg.org/#concept-opaque-host-parser>
	pub fn parse_opaque(input: &str) -> Result<Self, ParseError> {
	if input.starts_with('[') {
	if !input.ends_with(']') {
	return Err(ParseError::InvalidIpv6Address)
	}
	return parse_ipv6addr(&input[1..input.len() - 1]).map(Host::Ipv6)
	}
	if input.find(\|c\| matches!(c,
	'\0' \| '\t' \| '\n' \| '\r' \| ' ' \| '#' \| '/' \| ':' \| '?' \| '@' \| '[' \| '\\' \| ']'
	)).is_some() {
	return Err(ParseError::InvalidDomainCharacter)
	}
	let s = utf8_percent_encode(input, SIMPLE_ENCODE_SET).to_string();
	Ok(Host::Domain(s))
	}
	}

	impl<S: AsRef<str>> fmt::Display for Host<S> {
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
	match *self {
	Host::Domain(ref domain) => domain.as_ref().fmt(f),
	Host::Ipv4(ref addr) => addr.fmt(f),
	Host::Ipv6(ref addr) => {
	f.write_str("[")?;
	write_ipv6(addr, f)?;
	f.write_str("]")
	}
	}
	}
	}

	/// This mostly exists because coherence rules don’t allow us to implement
	/// `ToSocketAddrs for (Host<S>, u16)`.
	#[derive(Clone, Debug)]
	pub struct HostAndPort<S=String> {
	pub host: Host<S>,
	pub port: u16,
	}

	impl<'a> HostAndPort<&'a str> {
	/// Return a copy of `self` that owns an allocated `String` but does not borrow an `&Url`.
	pub fn to_owned(&self) -> HostAndPort<String> {
	HostAndPort {
	host: self.host.to_owned(),
	port: self.port
	}
	}
	}

	impl<S: AsRef<str>> fmt::Display for HostAndPort<S> {
	fn fmt(&self, f: &mut Formatter) -> fmt::Result {
	self.host.fmt(f)?;
	f.write_str(":")?;
	self.port.fmt(f)
	}
	}


	impl<S: AsRef<str>> ToSocketAddrs for HostAndPort<S> {
	type Iter = SocketAddrs;

	fn to_socket_addrs(&self) -> io::Result<Self::Iter> {
	let port = self.port;
	match self.host {
	Host::Domain(ref domain) => Ok(SocketAddrs {
	// FIXME: use std::net::lookup_host when it’s stable.
	state: SocketAddrsState::Domain((domain.as_ref(), port).to_socket_addrs()?)
	}),
	Host::Ipv4(address) => Ok(SocketAddrs {
	state: SocketAddrsState::One(SocketAddr::V4(SocketAddrV4::new(address, port)))
	}),
	Host::Ipv6(address) => Ok(SocketAddrs {
	state: SocketAddrsState::One(SocketAddr::V6(SocketAddrV6::new(address, port, 0, 0)))
	}),
	}
	}
	}

	/// Socket addresses for an URL.
	#[derive(Debug)]
	pub struct SocketAddrs {
	state: SocketAddrsState
	}

	#[derive(Debug)]
	enum SocketAddrsState {
	Domain(vec::IntoIter<SocketAddr>),
	One(SocketAddr),
	Done,
	}

	impl Iterator for SocketAddrs {
	type Item = SocketAddr;
	fn next(&mut self) -> Option<SocketAddr> {
	match self.state {
	SocketAddrsState::Domain(ref mut iter) => iter.next(),
	SocketAddrsState::One(s) => {
	self.state = SocketAddrsState::Done;
	Some(s)
	}
	SocketAddrsState::Done => None
	}
	}
	}

	fn write_ipv6(addr: &Ipv6Addr, f: &mut Formatter) -> fmt::Result {
	let segments = addr.segments();
	let (compress_start, compress_end) = longest_zero_sequence(&segments);
	let mut i = 0;
	while i < 8 {
	if i == compress_start {
	f.write_str(":")?;
	if i == 0 {
	f.write_str(":")?;
	}
	if compress_end < 8 {
	i = compress_end;
	} else {
	break;
	}
	}
	write!(f, "{:x}", segments[i as usize])?;
	if i < 7 {
	f.write_str(":")?;
	}
	i += 1;
	}
	Ok(())
	}

	// https://url.spec.whatwg.org/#concept-ipv6-serializer step 2 and 3
	fn longest_zero_sequence(pieces: &[u16; 8]) -> (isize, isize) {
	let mut longest = -1;
	let mut longest_length = -1;
	let mut start = -1;
	macro_rules! finish_sequence(
	($end: expr) => {
	if start >= 0 {
	let length = $end - start;
	if length > longest_length {
	longest = start;
	longest_length = length;
	}
	}
	};
	);
	for i in 0..8 {
	if pieces[i as usize] == 0 {
	if start < 0 {
	start = i;
	}
	} else {
	finish_sequence!(i);
	start = -1;
	}
	}
	finish_sequence!(8);
	// https://url.spec.whatwg.org/#concept-ipv6-serializer
	// step 3: ignore lone zeroes
	if longest_length < 2 {
	(-1, -2)
	} else {
	(longest, longest + longest_length)
	}
	}

	/// <https://url.spec.whatwg.org/#ipv4-number-parser>
	fn parse_ipv4number(mut input: &str) -> Result<Option<u32>, ()> {
	let mut r = 10;
	if input.starts_with("0x") \|\| input.starts_with("0X") {
	input = &input[2..];
	r = 16;
	} else if input.len() >= 2 && input.starts_with('0') {
	input = &input[1..];
	r = 8;
	}

	// At the moment we can't know the reason why from_str_radix fails
	// https://github.com/rust-lang/rust/issues/22639
	// So instead we check if the input looks like a real number and only return
	// an error when it's an overflow.
	let valid_number = match r {
	8 => input.chars().all(\|c\| c >= '0' && c <='7'),
	10 => input.chars().all(\|c\| c >= '0' && c <='9'),
	16 => input.chars().all(\|c\| (c >= '0' && c <='9') \|\| (c >='a' && c <= 'f') \|\| (c >= 'A' && c <= 'F')),
	_ => false
	};

	if !valid_number {
	return Ok(None);
	}

	if input.is_empty() {
	return Ok(Some(0));
	}
	if input.starts_with('+') {
	return Ok(None);
	}
	match u32::from_str_radix(input, r) {
	Ok(number) => Ok(Some(number)),
	Err(_) => Err(()),
	}
	}

	/// <https://url.spec.whatwg.org/#concept-ipv4-parser>
	fn parse_ipv4addr(input: &str) -> ParseResult<Option<Ipv4Addr>> {
	if input.is_empty() {
	return Ok(None)
	}
	let mut parts: Vec<&str> = input.split('.').collect();
	if parts.last() == Some(&"") {
	parts.pop();
	}
	if parts.len() > 4 {
	return Ok(None);
	}
	let mut numbers: Vec<u32> = Vec::new();
	let mut overflow = false;
	for part in parts {
	if part == "" {
	return Ok(None);
	}
	match parse_ipv4number(part) {
	Ok(Some(n)) => numbers.push(n),
	Ok(None) => return Ok(None),
	Err(()) => overflow = true
	};
	}
	if overflow {
	return Err(ParseError::InvalidIpv4Address);
	}
	let mut ipv4 = numbers.pop().expect("a non-empty list of numbers");
	// Equivalent to: ipv4 >= 256 ** (4 − numbers.len())
	if ipv4 > u32::max_value() >> (8 * numbers.len() as u32) {
	return Err(ParseError::InvalidIpv4Address);
	}
	if numbers.iter().any(\|x\| *x > 255) {
	return Err(ParseError::InvalidIpv4Address);
	}
	for (counter, n) in numbers.iter().enumerate() {
	ipv4 += n << (8 * (3 - counter as u32))
	}
	Ok(Some(Ipv4Addr::from(ipv4)))
	}

	/// <https://url.spec.whatwg.org/#concept-ipv6-parser>
	fn parse_ipv6addr(input: &str) -> ParseResult<Ipv6Addr> {
	let input = input.as_bytes();
	let len = input.len();
	let mut is_ip_v4 = false;
	let mut pieces = [0, 0, 0, 0, 0, 0, 0, 0];
	let mut piece_pointer = 0;
	let mut compress_pointer = None;
	let mut i = 0;

	if len < 2 {
	return Err(ParseError::InvalidIpv6Address)
	}

	if input[0] == b':' {
	if input[1] != b':' {
	return Err(ParseError::InvalidIpv6Address)
	}
	i = 2;
	piece_pointer = 1;
	compress_pointer = Some(1);
	}

	while i < len {
	if piece_pointer == 8 {
	return Err(ParseError::InvalidIpv6Address)
	}
	if input[i] == b':' {
	if compress_pointer.is_some() {
	return Err(ParseError::InvalidIpv6Address)
	}
	i += 1;
	piece_pointer += 1;
	compress_pointer = Some(piece_pointer);
	continue
	}
	let start = i;
	let end = cmp::min(len, start + 4);
	let mut value = 0u16;
	while i < end {
	match (input[i] as char).to_digit(16) {
	Some(digit) => {
	value = value * 0x10 + digit as u16;
	i += 1;
	},
	None => break
	}
	}
	if i < len {
	match input[i] {
	b'.' => {
	if i == start {
	return Err(ParseError::InvalidIpv6Address)
	}
	i = start;
	if piece_pointer > 6 {
	return Err(ParseError::InvalidIpv6Address)
	}
	is_ip_v4 = true;
	},
	b':' => {
	i += 1;
	if i == len {
	return Err(ParseError::InvalidIpv6Address)
	}
	},
	_ => return Err(ParseError::InvalidIpv6Address)
	}
	}
	if is_ip_v4 {
	break
	}
	pieces[piece_pointer] = value;
	piece_pointer += 1;
	}

	if is_ip_v4 {
	if piece_pointer > 6 {
	return Err(ParseError::InvalidIpv6Address)
	}
	let mut numbers_seen = 0;
	while i < len {
	if numbers_seen > 0 {
	if numbers_seen < 4 && (i < len && input[i] == b'.') {
	i += 1
	} else {
	return Err(ParseError::InvalidIpv6Address)
	}
	}

	let mut ipv4_piece = None;
	while i < len {
	let digit = match input[i] {
	c @ b'0' ... b'9' => c - b'0',
	_ => break
	};
	match ipv4_piece {
	None => ipv4_piece = Some(digit as u16),
	Some(0) => return Err(ParseError::InvalidIpv6Address), // No leading zero
	Some(ref mut v) => {
	v = v * 10 + digit as u16;
	if *v > 255 {
	return Err(ParseError::InvalidIpv6Address)
	}
	}
	}
	i += 1;
	}

	pieces[piece_pointer] = if let Some(v) = ipv4_piece {
	pieces[piece_pointer] * 0x100 + v
	} else {
	return Err(ParseError::InvalidIpv6Address)
	};
	numbers_seen += 1;

	if numbers_seen == 2 \|\| numbers_seen == 4 {
	piece_pointer += 1;
	}
	}

	if numbers_seen != 4 {
	return Err(ParseError::InvalidIpv6Address)
	}
	}

	if i < len {
	return Err(ParseError::InvalidIpv6Address)
	}

	match compress_pointer {
	Some(compress_pointer) => {
	let mut swaps = piece_pointer - compress_pointer;
	piece_pointer = 7;
	while swaps > 0 {
	pieces.swap(piece_pointer, compress_pointer + swaps - 1);
	swaps -= 1;
	piece_pointer -= 1;
	}
	}
	_ => if piece_pointer != 8 {
	return Err(ParseError::InvalidIpv6Address)
	}
	}
	Ok(Ipv6Addr::new(pieces[0], pieces[1], pieces[2], pieces[3],
	pieces[4], pieces[5], pieces[6], pieces[7]))
	}