Elaborate on ip_addr bit conversion endianness

Adds explanation of how endianness is handled when converting `Ipv4Addr`
and `Ipv6Addr` to and from bits.

Addresses #113744
This commit is contained in:
Chris Eckhardt 2023-12-01 10:30:09 -06:00
parent caf7300432
commit c3bb1b50a5

View File

@ -468,7 +468,13 @@ impl Ipv4Addr {
#[unstable(feature = "ip_bits", issue = "113744")]
pub const BITS: u32 = 32;
/// Converts an IPv4 address into host byte order `u32`.
/// Converts an IPv4 address into a `u32` representation using native byte order.
///
/// Although IPv4 addresses are big-endian, the `u32` value will use the target platform's
/// native byte order. That is, the `u32` value is an integer representation of the IPv4
/// address and not an integer interpretation of the IPv4 address's big-endian bitstring. This
/// means that the `u32` value masked with `0xffffff00` will set the last octet in the address
/// to 0, regardless of the target platform's endianness.
///
/// # Examples
///
@ -479,6 +485,16 @@ impl Ipv4Addr {
/// let addr = Ipv4Addr::new(0x12, 0x34, 0x56, 0x78);
/// assert_eq!(0x12345678, addr.to_bits());
/// ```
///
/// ```
/// #![feature(ip_bits)]
/// use std::net::Ipv4Addr;
///
/// let addr = Ipv4Addr::new(0x12, 0x34, 0x56, 0x78);
/// let addr_bits = addr.to_bits() & 0xffffff00;
/// assert_eq!(Ipv4Addr::new(0x12, 0x34, 0x56, 0x00), Ipv4Addr::from_bits(addr_bits));
///
/// ```
#[rustc_const_unstable(feature = "ip_bits", issue = "113744")]
#[unstable(feature = "ip_bits", issue = "113744")]
#[must_use]
@ -487,7 +503,9 @@ impl Ipv4Addr {
u32::from_be_bytes(self.octets)
}
/// Converts a host byte order `u32` into an IPv4 address.
/// Converts a native byte order `u32` into an IPv4 address.
///
/// See [`Ipv4Addr::to_bits`] for an explanation on endianness.
///
/// # Examples
///
@ -1224,7 +1242,13 @@ impl Ipv6Addr {
#[unstable(feature = "ip_bits", issue = "113744")]
pub const BITS: u32 = 128;
/// Converts an IPv6 address into host byte order `u128`.
/// Converts an IPv6 address into a `u128` representation using native byte order.
///
/// Although IPv6 addresses are big-endian, the `u128` value will use the target platform's
/// native byte order. That is, the `u128` value is an integer representation of the IPv6
/// address and not an integer interpretation of the IPv6 address's big-endian bitstring. This
/// means that the `u128` value masked with `0xffffffffffffffffffffffffffff0000_u128` will set
/// the last segment in the address to 0, regardless of the target platform's endianness.
///
/// # Examples
///
@ -1238,6 +1262,24 @@ impl Ipv6Addr {
/// );
/// assert_eq!(0x102030405060708090A0B0C0D0E0F00D_u128, u128::from(addr));
/// ```
///
/// ```
/// #![feature(ip_bits)]
/// use std::net::Ipv6Addr;
///
/// let addr = Ipv6Addr::new(
/// 0x1020, 0x3040, 0x5060, 0x7080,
/// 0x90A0, 0xB0C0, 0xD0E0, 0xF00D,
/// );
/// let addr_bits = addr.to_bits() & 0xffffffffffffffffffffffffffff0000_u128;
/// assert_eq!(
/// Ipv6Addr::new(
/// 0x1020, 0x3040, 0x5060, 0x7080,
/// 0x90A0, 0xB0C0, 0xD0E0, 0x0000,
/// ),
/// Ipv6Addr::from_bits(addr_bits));
///
/// ```
#[rustc_const_unstable(feature = "ip_bits", issue = "113744")]
#[unstable(feature = "ip_bits", issue = "113744")]
#[must_use]
@ -1246,7 +1288,9 @@ impl Ipv6Addr {
u128::from_be_bytes(self.octets)
}
/// Converts a host byte order `u128` into an IPv6 address.
/// Converts a native byte order `u128` into an IPv6 address.
///
/// See [`Ipv6Addr::to_bits`] for an explanation on endianness.
///
/// # Examples
///