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Implement padding for IpAddr without heap alloc
This commit is contained in:
Dario Gonzalez
parent
acb6690e1d
commit
915686d069
@ -9,6 +9,7 @@
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use crate::cmp::Ordering;
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use crate::fmt;
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use crate::hash;
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use crate::io::Write;
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use crate::sys::net::netc as c;
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use crate::sys_common::{AsInner, FromInner};
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@ -833,8 +834,16 @@ impl From<Ipv6Addr> for IpAddr {
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#[stable(feature = "rust1", since = "1.0.0")]
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impl fmt::Display for Ipv4Addr {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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const IPV4_BUF_LEN: usize = 15; // Long enough for the longest possible IPv4 address
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let mut buf = [0u8; IPV4_BUF_LEN];
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let mut buf_slice = &mut buf[..];
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let octets = self.octets();
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write!(fmt, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3])
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// Note: The call to write should never fail, hence the unwrap
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write!(buf_slice, "{}.{}.{}.{}", octets[0], octets[1], octets[2], octets[3]).unwrap();
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let len = IPV4_BUF_LEN - buf_slice.len();
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// This unsafe is OK because we know what is being written to the buffer
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let buf = unsafe { crate::str::from_utf8_unchecked(&buf[..len]) };
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fmt.pad(buf)
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}
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}
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@ -1495,18 +1504,40 @@ impl Ipv6Addr {
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#[stable(feature = "rust1", since = "1.0.0")]
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impl fmt::Display for Ipv6Addr {
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fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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// Note: The calls to write should never fail, hence the unwraps in the function
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// Long enough for the longest possible IPv6: 39
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const IPV6_BUF_LEN: usize = 39;
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let mut buf = [0u8; IPV6_BUF_LEN];
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let mut buf_slice = &mut buf[..];
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match self.segments() {
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// We need special cases for :: and ::1, otherwise they're formatted
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// as ::0.0.0.[01]
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[0, 0, 0, 0, 0, 0, 0, 0] => write!(fmt, "::"),
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[0, 0, 0, 0, 0, 0, 0, 1] => write!(fmt, "::1"),
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[0, 0, 0, 0, 0, 0, 0, 0] => write!(buf_slice, "::").unwrap(),
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[0, 0, 0, 0, 0, 0, 0, 1] => write!(buf_slice, "::1").unwrap(),
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// Ipv4 Compatible address
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[0, 0, 0, 0, 0, 0, g, h] => {
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write!(fmt, "::{}.{}.{}.{}", (g >> 8) as u8, g as u8, (h >> 8) as u8, h as u8)
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write!(
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buf_slice,
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"::{}.{}.{}.{}",
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(g >> 8) as u8,
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g as u8,
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(h >> 8) as u8,
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h as u8
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)
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.unwrap();
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}
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// Ipv4-Mapped address
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[0, 0, 0, 0, 0, 0xffff, g, h] => {
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write!(fmt, "::ffff:{}.{}.{}.{}", (g >> 8) as u8, g as u8, (h >> 8) as u8, h as u8)
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write!(
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buf_slice,
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"::ffff:{}.{}.{}.{}",
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(g >> 8) as u8,
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g as u8,
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(h >> 8) as u8,
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h as u8
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)
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.unwrap();
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}
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_ => {
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fn find_zero_slice(segments: &[u16; 8]) -> (usize, usize) {
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@ -1539,25 +1570,33 @@ impl fmt::Display for Ipv6Addr {
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let (zeros_at, zeros_len) = find_zero_slice(&self.segments());
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if zeros_len > 1 {
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fn fmt_subslice(segments: &[u16], fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
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fn fmt_subslice(segments: &[u16], buf: &mut &mut [u8]) {
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if !segments.is_empty() {
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write!(fmt, "{:x}", segments[0])?;
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write!(*buf, "{:x}", segments[0]).unwrap();
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for &seg in &segments[1..] {
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write!(fmt, ":{:x}", seg)?;
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write!(*buf, ":{:x}", seg).unwrap();
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}
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}
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Ok(())
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}
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fmt_subslice(&self.segments()[..zeros_at], fmt)?;
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fmt.write_str("::")?;
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fmt_subslice(&self.segments()[zeros_at + zeros_len..], fmt)
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fmt_subslice(&self.segments()[..zeros_at], &mut buf_slice);
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write!(buf_slice, "::").unwrap();
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fmt_subslice(&self.segments()[zeros_at + zeros_len..], &mut buf_slice);
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} else {
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let &[a, b, c, d, e, f, g, h] = &self.segments();
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write!(fmt, "{:x}:{:x}:{:x}:{:x}:{:x}:{:x}:{:x}:{:x}", a, b, c, d, e, f, g, h)
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write!(
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buf_slice,
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"{:x}:{:x}:{:x}:{:x}:{:x}:{:x}:{:x}:{:x}",
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a, b, c, d, e, f, g, h
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)
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.unwrap();
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}
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}
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}
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let len = IPV6_BUF_LEN - buf_slice.len();
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// This is safe because we know exactly what can be in this buffer
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let buf = unsafe { crate::str::from_utf8_unchecked(&buf[..len]) };
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fmt.pad(buf)
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}
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}
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@ -1896,6 +1935,18 @@ mod tests {
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assert_eq!(None, none);
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}
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#[test]
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fn ipv4_addr_to_string() {
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// Short address
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assert_eq!(Ipv4Addr::new(1, 1, 1, 1).to_string(), "1.1.1.1");
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// Long address
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assert_eq!(Ipv4Addr::new(127, 127, 127, 127).to_string(), "127.127.127.127");
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// Test padding
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assert_eq!(&format!("{:16}", Ipv4Addr::new(1, 1, 1, 1)), "1.1.1.1 ");
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assert_eq!(&format!("{:>16}", Ipv4Addr::new(1, 1, 1, 1)), " 1.1.1.1");
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}
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#[test]
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fn ipv6_addr_to_string() {
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// ipv4-mapped address
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@ -1909,6 +1960,22 @@ mod tests {
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// v6 address with no zero segments
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assert_eq!(Ipv6Addr::new(8, 9, 10, 11, 12, 13, 14, 15).to_string(), "8:9:a:b:c:d:e:f");
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// longest possible IPv6 length
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assert_eq!(
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Ipv6Addr::new(0x1111, 0x2222, 0x3333, 0x4444, 0x5555, 0x6666, 0x7777, 0x8888)
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.to_string(),
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"1111:2222:3333:4444:5555:6666:7777:8888"
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);
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// padding
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assert_eq!(
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&format!("{:20}", Ipv6Addr::new(1, 2, 3, 4, 5, 6, 7, 8)),
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"1:2:3:4:5:6:7:8 "
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);
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assert_eq!(
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&format!("{:>20}", Ipv6Addr::new(1, 2, 3, 4, 5, 6, 7, 8)),
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" 1:2:3:4:5:6:7:8"
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);
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// reduce a single run of zeros
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assert_eq!(
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"ae::ffff:102:304",
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