diff --git a/library/std/src/net/ip.rs b/library/std/src/net/ip.rs index ccaacbf1a58a9..2c0025bcba069 100644 --- a/library/std/src/net/ip.rs +++ b/library/std/src/net/ip.rs @@ -1473,6 +1473,37 @@ impl Ipv6Addr { (self.segments()[0] & 0xff00) == 0xff00 } + /// Converts this address to an [IPv4 address] if it's an "IPv4-mapped IPv6 address" + /// defined in [IETF RFC 4291 section 2.5.5.2], otherwise returns [`None`]. + /// + /// `::ffff:a.b.c.d` becomes `a.b.c.d`. + /// All addresses *not* starting with `::ffff` will return `None`. + /// + /// [IPv4 address]: ../../std/net/struct.Ipv4Addr.html + /// [`None`]: ../../std/option/enum.Option.html#variant.None + /// [IETF RFC 4291 section 2.5.5.2]: https://tools.ietf.org/html/rfc4291#section-2.5.5.2 + /// + /// # Examples + /// + /// ``` + /// #![feature(ip)] + /// + /// use std::net::{Ipv4Addr, Ipv6Addr}; + /// + /// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).to_ipv4_mapped(), None); + /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).to_ipv4_mapped(), + /// Some(Ipv4Addr::new(192, 10, 2, 255))); + /// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4_mapped(), None); + /// ``` + pub fn to_ipv4_mapped(&self) -> Option { + match self.octets() { + [0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0xff, 0xff, a, b, c, d] => { + Some(Ipv4Addr::new(a, b, c, d)) + } + _ => None, + } + } + /// Converts this address to an [IPv4 address]. Returns [`None`] if this address is /// neither IPv4-compatible or IPv4-mapped. /// @@ -2070,6 +2101,15 @@ mod tests { ); } + #[test] + fn ipv6_to_ipv4_mapped() { + assert_eq!( + Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0x1234, 0x5678).to_ipv4_mapped(), + Some(Ipv4Addr::new(0x12, 0x34, 0x56, 0x78)) + ); + assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0x1234, 0x5678).to_ipv4_mapped(), None); + } + #[test] fn ipv6_to_ipv4() { assert_eq!(