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Remove is_unicast_link_local_strict

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This commit is contained in:
Christiaan Dirkx
2021-05-29 23:48:56 +02:00
parent ce0d64e03e
commit c1f0c15382
2 changed files with 28 additions and 102 deletions
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112
library/std/src/net/ip.rs
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@@ -1267,22 +1267,31 @@ impl Ipv6Addr {
(self.segments()[0] & 0xfe00) == 0xfc00
}
/// Returns [`true`] if the address is a unicast link-local address (`fe80::/64`).
/// Returns `true` if the address is a unicast address with link-local scope,
/// as defined in [RFC 4291].
///
/// A common misconception is to think that "unicast link-local addresses start with
/// `fe80::`", but [IETF RFC 4291] actually defines a stricter format for these addresses:
/// A unicast address has link-local scope if it has the prefix `fe80::/10`, as per [RFC 4291 section 2.4].
/// Note that this encompasses more addresses than those defined in [RFC 4291 section 2.5.6],
/// which describes "Link-Local IPv6 Unicast Addresses" as having the following stricter format:
///
/// ```no_rust
/// | 10 |
/// | bits | 54 bits | 64 bits |
/// ```text
/// | 10 bits | 54 bits | 64 bits |
/// +----------+-------------------------+----------------------------+
/// |1111111010| 0 | interface ID |
/// +----------+-------------------------+----------------------------+
/// ```
/// So while currently the only addresses with link-local scope an application will encounter are all in `fe80::/64`,
/// this might change in the future with the publication of new standards. More addresses in `fe80::/10` could be allocated,
/// and those addresses will have link-local scope.
///
/// This method validates the format defined in the RFC and won't recognize addresses
/// like `fe80:0:0:1::` or `fe81::` as unicast link-local addresses.
/// If you need a less strict validation, use [`Ipv6Addr::is_unicast_link_local()`] instead.
/// Also note that while [RFC 4291 section 2.5.3] mentions about the [loopback address] (`::1`) that "it is treated as having Link-Local scope",
/// this does not mean that the loopback address actually has link-local scope and this method will return `false` on it.
///
/// [RFC 4291]: https://tools.ietf.org/html/rfc4291
/// [RFC 4291 section 2.4]: https://tools.ietf.org/html/rfc4291#section-2.4
/// [RFC 4291 section 2.5.3]: https://tools.ietf.org/html/rfc4291#section-2.5.3
/// [RFC 4291 section 2.5.6]: https://tools.ietf.org/html/rfc4291#section-2.5.6
/// [loopback address]: Ipv6Addr::LOCALHOST
///
/// # Examples
///
@@ -1291,86 +1300,17 @@ impl Ipv6Addr {
///
/// use std::net::Ipv6Addr;
///
/// let ip = Ipv6Addr::new(0xfe80, 0, 0, 0, 0, 0, 0, 0);
/// assert!(ip.is_unicast_link_local_strict());
/// // The loopback address (`::1`) does not actually have link-local scope.
/// assert_eq!(Ipv6Addr::LOCALHOST.is_unicast_link_local(), false);
///
/// let ip = Ipv6Addr::new(0xfe80, 0, 0, 0, 0xffff, 0xffff, 0xffff, 0xffff);
/// assert!(ip.is_unicast_link_local_strict());
/// // Only addresses in `fe80::/10` have link-local scope.
/// assert_eq!(Ipv6Addr::new(0x2001, 0xdb8, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), false);
/// assert_eq!(Ipv6Addr::new(0xfe80, 0, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), true);
///
/// let ip = Ipv6Addr::new(0xfe80, 0, 0, 1, 0, 0, 0, 0);
/// assert!(!ip.is_unicast_link_local_strict());
/// assert!(ip.is_unicast_link_local());
///
/// let ip = Ipv6Addr::new(0xfe81, 0, 0, 0, 0, 0, 0, 0);
/// assert!(!ip.is_unicast_link_local_strict());
/// assert!(ip.is_unicast_link_local());
/// // Addresses outside the stricter `fe80::/64` also have link-local scope.
/// assert_eq!(Ipv6Addr::new(0xfe80, 0, 0, 1, 0, 0, 0, 0).is_unicast_link_local(), true);
/// assert_eq!(Ipv6Addr::new(0xfe81, 0, 0, 0, 0, 0, 0, 0).is_unicast_link_local(), true);
/// ```
///
/// # See also
///
/// - [IETF RFC 4291 section 2.5.6]
/// - [RFC 4291 errata 4406] (which has been rejected but provides useful
/// insight)
/// - [`Ipv6Addr::is_unicast_link_local()`]
///
/// [IETF RFC 4291]: https://tools.ietf.org/html/rfc4291
/// [IETF RFC 4291 section 2.5.6]: https://tools.ietf.org/html/rfc4291#section-2.5.6
/// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[unstable(feature = "ip", issue = "27709")]
#[inline]
pub const fn is_unicast_link_local_strict(&self) -> bool {
matches!(self.segments(), [0xfe80, 0, 0, 0, ..])
}
/// Returns [`true`] if the address is a unicast link-local address (`fe80::/10`).
///
/// This method returns [`true`] for addresses in the range reserved by [RFC 4291 section 2.4],
/// i.e. addresses with the following format:
///
/// ```no_rust
/// | 10 |
/// | bits | 54 bits | 64 bits |
/// +----------+-------------------------+----------------------------+
/// |1111111010| arbitratry value | interface ID |
/// +----------+-------------------------+----------------------------+
/// ```
///
/// As a result, this method considers addresses such as `fe80:0:0:1::` or `fe81::` to be
/// unicast link-local addresses, whereas [`Ipv6Addr::is_unicast_link_local_strict()`] does not.
/// If you need a strict validation fully compliant with the RFC, use
/// [`Ipv6Addr::is_unicast_link_local_strict()`] instead.
///
/// # Examples
///
/// ```
/// #![feature(ip)]
///
/// use std::net::Ipv6Addr;
///
/// let ip = Ipv6Addr::new(0xfe80, 0, 0, 0, 0, 0, 0, 0);
/// assert!(ip.is_unicast_link_local());
///
/// let ip = Ipv6Addr::new(0xfe80, 0, 0, 0, 0xffff, 0xffff, 0xffff, 0xffff);
/// assert!(ip.is_unicast_link_local());
///
/// let ip = Ipv6Addr::new(0xfe80, 0, 0, 1, 0, 0, 0, 0);
/// assert!(ip.is_unicast_link_local());
/// assert!(!ip.is_unicast_link_local_strict());
///
/// let ip = Ipv6Addr::new(0xfe81, 0, 0, 0, 0, 0, 0, 0);
/// assert!(ip.is_unicast_link_local());
/// assert!(!ip.is_unicast_link_local_strict());
/// ```
///
/// # See also
///
/// - [IETF RFC 4291 section 2.4]
/// - [RFC 4291 errata 4406] (which has been rejected but provides useful
/// insight)
///
/// [IETF RFC 4291 section 2.4]: https://tools.ietf.org/html/rfc4291#section-2.4
/// [RFC 4291 errata 4406]: https://www.rfc-editor.org/errata/eid4406
#[rustc_const_unstable(feature = "const_ipv6", issue = "76205")]
#[unstable(feature = "ip", issue = "27709")]
#[inline]