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Fix Ipv6Addr::to_ipv4 #75046

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Fix Ipv6Addr::to_ipv4 #75046

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39 changes: 20 additions & 19 deletions library/std/src/net/ip.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -758,6 +758,9 @@ impl Ipv4Addr {
///
/// a.b.c.d becomes ::a.b.c.d
///
/// Note: The IPv4 address used in the IPv4-compatible IPv6 address must be a
/// globally-unique IPv4 unicast address. This implementation does *not* check for it.
///
/// [IPv6 address]: ../../std/net/struct.Ipv6Addr.html
///
/// # Examples
Expand Down Expand Up @@ -1493,6 +1496,9 @@ impl Ipv6Addr {
///
/// ::a.b.c.d and ::ffff:a.b.c.d become a.b.c.d
///
/// Note: The IPv4 address used in the IPv4-compatible IPv6 address must be a
/// globally-unique IPv4 unicast address.
///
/// [IPv4 address]: ../../std/net/struct.Ipv4Addr.html
/// [`None`]: ../../std/option/enum.Option.html#variant.None
///
Expand All @@ -1504,14 +1510,19 @@ impl Ipv6Addr {
/// assert_eq!(Ipv6Addr::new(0xff00, 0, 0, 0, 0, 0, 0, 0).to_ipv4(), None);
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0xffff, 0xc00a, 0x2ff).to_ipv4(),
/// Some(Ipv4Addr::new(192, 10, 2, 255)));
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4(),
/// Some(Ipv4Addr::new(0, 0, 0, 1)));
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0, 1).to_ipv4(), None);
/// assert_eq!(Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0x1234, 0x5678).to_ipv4(),
/// Some(Ipv4Addr::new(18, 52, 86, 120)));
/// ```
#[stable(feature = "rust1", since = "1.0.0")]
pub fn to_ipv4(&self) -> Option<Ipv4Addr> {
match self.segments() {
[0, 0, 0, 0, 0, f, g, h] if f == 0 || f == 0xffff => {
Some(Ipv4Addr::new((g >> 8) as u8, g as u8, (h >> 8) as u8, h as u8))
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))
}
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, a, b, c, d] => {
let ipv4 = Ipv4Addr::new(a, b, c, d);
if ipv4.is_global() { Some(ipv4) } else { None }
}
_ => None,
}
Expand Down Expand Up @@ -1542,13 +1553,7 @@ impl fmt::Display for Ipv6Addr {
if f.precision().is_none() && f.width().is_none() {
let segments = self.segments();

// Special case for :: and ::1; otherwise they get written with the
// IPv4 formatter
if self.is_unspecified() {
f.write_str("::")
} else if self.is_loopback() {
f.write_str("::1")
} else if let Some(ipv4) = self.to_ipv4() {
if let Some(ipv4) = self.to_ipv4() {
match segments[5] {
// IPv4 Compatible address
0 => write!(f, "::{}", ipv4),
Expand Down Expand Up @@ -2025,8 +2030,8 @@ mod tests {
assert_eq!(a1.to_string(), "::ffff:192.0.2.128");

// ipv4-compatible address
let a1 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0xc000, 0x280);
assert_eq!(a1.to_string(), "::192.0.2.128");
let a1 = Ipv6Addr::new(0, 0, 0, 0, 0, 0, 0x102, 0x304);
assert_eq!(a1.to_string(), "::1.2.3.4");

// v6 address with no zero segments
assert_eq!(Ipv6Addr::new(8, 9, 10, 11, 12, 13, 14, 15).to_string(), "8:9:a:b:c:d:e:f");
Expand Down Expand Up @@ -2495,11 +2500,7 @@ mod tests {

check!("::1", &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1], loopback);

check!(
"::0.0.0.2",
&[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2],
global | unicast_global
);
check!("::2", &[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2], global | unicast_global);

check!("1::", &[0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0], global | unicast_global);

Expand Down