addr.rs - source
Description: Source of the Rust file `library/std/src/sys/unix/ext/net/addr.rs`.
Keywords: rust, rustlang, rust-lang

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    use crate::ffi::OsStr;
    use crate::os::unix::ffi::OsStrExt;
    use crate::path::Path;
    use crate::sys::cvt;
    use crate::{ascii, fmt, io, mem};

    // FIXME(#43348): Make libc adapt #[doc(cfg(...))] so we don't need these fake definitions here?
    #[cfg(not(unix))]
    #[allow(non_camel_case_types)]
    mod libc {
        pub use libc::c_int;
        pub type socklen_t = u32;
        pub struct sockaddr;
        #[derive(Clone)]
        pub struct sockaddr_un;
    }

    fn sun_path_offset(addr: &libc::sockaddr_un) -> usize {
        // Work with an actual instance of the type since using a null pointer is UB
        let base = addr as *const _ as usize;
        let path = &addr.sun_path as *const _ as usize;
        path - base
    }

    pub(super) unsafe fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
        let mut addr: libc::sockaddr_un = mem::zeroed();
        addr.sun_family = libc::AF_UNIX as libc::sa_family_t;

        let bytes = path.as_os_str().as_bytes();

        if bytes.contains(&0) {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "paths may not contain interior null bytes",
            ));
        }

        if bytes.len() >= addr.sun_path.len() {
            return Err(io::Error::new(
                io::ErrorKind::InvalidInput,
                "path must be shorter than SUN_LEN",
            ));
        }
        for (dst, src) in addr.sun_path.iter_mut().zip(bytes.iter()) {
            *dst = *src as libc::c_char;
        }
        // null byte for pathname addresses is already there because we zeroed the
        // struct

        let mut len = sun_path_offset(&addr) + bytes.len();
        match bytes.get(0) {
            Some(&0) | None => {}
            Some(_) => len += 1,
        }
        Ok((addr, len as libc::socklen_t))
    }

    enum AddressKind<'a> {
        Unnamed,
        Pathname(&'a Path),
        Abstract(&'a [u8]),
    }

    struct AsciiEscaped<'a>(&'a [u8]);

    impl<'a> fmt::Display for AsciiEscaped<'a> {
        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
            write!(fmt, "\"")?;
            for byte in self.0.iter().cloned().flat_map(ascii::escape_default) {
                write!(fmt, "{}", byte as char)?;
            }
            write!(fmt, "\"")
        }
    }

    /// An address associated with a Unix socket.
    ///
    /// # Examples
    ///
    /// ```
    /// use std::os::unix::net::UnixListener;
    ///
    /// let socket = match UnixListener::bind("/tmp/sock") {
    ///     Ok(sock) => sock,
    ///     Err(e) => {
    ///         println!("Couldn't bind: {:?}", e);
    ///         return
    ///     }
    /// };
    /// let addr = socket.local_addr().expect("Couldn't get local address");
    /// ```
    #[derive(Clone)]
    #[stable(feature = "unix_socket", since = "1.10.0")]
    pub struct SocketAddr {
        addr: libc::sockaddr_un,
        len: libc::socklen_t,
    }

    impl SocketAddr {
        pub(super) fn new<F>(f: F) -> io::Result<SocketAddr>
        where
            F: FnOnce(*mut libc::sockaddr, *mut libc::socklen_t) -> libc::c_int,
        {
            unsafe {
                let mut addr: libc::sockaddr_un = mem::zeroed();
                let mut len = mem::size_of::<libc::sockaddr_un>() as libc::socklen_t;
                cvt(f(&mut addr as *mut _ as *mut _, &mut len))?;
                SocketAddr::from_parts(addr, len)
            }
        }

        pub(super) fn from_parts(
            addr: libc::sockaddr_un,
            mut len: libc::socklen_t,
        ) -> io::Result<SocketAddr> {
            if len == 0 {
                // When there is a datagram from unnamed unix socket
                // linux returns zero bytes of address
                len = sun_path_offset(&addr) as libc::socklen_t; // i.e., zero-length address
            } else if addr.sun_family != libc::AF_UNIX as libc::sa_family_t {
                return Err(io::Error::new(
                    io::ErrorKind::InvalidInput,
                    "file descriptor did not correspond to a Unix socket",
                ));
            }

            Ok(SocketAddr { addr, len })
        }

        /// Returns `true` if the address is unnamed.
        ///
        /// # Examples
        ///
        /// A named address:
        ///
        /// ```no_run
        /// use std::os::unix::net::UnixListener;
        ///
        /// fn main() -> std::io::Result<()> {
        ///     let socket = UnixListener::bind("/tmp/sock")?;
        ///     let addr = socket.local_addr().expect("Couldn't get local address");
        ///     assert_eq!(addr.is_unnamed(), false);
        ///     Ok(())
        /// }
        /// ```
        ///
        /// An unnamed address:
        ///
        /// ```
        /// use std::os::unix::net::UnixDatagram;
        ///
        /// fn main() -> std::io::Result<()> {
        ///     let socket = UnixDatagram::unbound()?;
        ///     let addr = socket.local_addr().expect("Couldn't get local address");
        ///     assert_eq!(addr.is_unnamed(), true);
        ///     Ok(())
        /// }
        /// ```
        #[stable(feature = "unix_socket", since = "1.10.0")]
        pub fn is_unnamed(&self) -> bool {
            if let AddressKind::Unnamed = self.address() { true } else { false }
        }

        /// Returns the contents of this address if it is a `pathname` address.
        ///
        /// # Examples
        ///
        /// With a pathname:
        ///
        /// ```no_run
        /// use std::os::unix::net::UnixListener;
        /// use std::path::Path;
        ///
        /// fn main() -> std::io::Result<()> {
        ///     let socket = UnixListener::bind("/tmp/sock")?;
        ///     let addr = socket.local_addr().expect("Couldn't get local address");
        ///     assert_eq!(addr.as_pathname(), Some(Path::new("/tmp/sock")));
        ///     Ok(())
        /// }
        /// ```
        ///
        /// Without a pathname:
        ///
        /// ```
        /// use std::os::unix::net::UnixDatagram;
        ///
        /// fn main() -> std::io::Result<()> {
        ///     let socket = UnixDatagram::unbound()?;
        ///     let addr = socket.local_addr().expect("Couldn't get local address");
        ///     assert_eq!(addr.as_pathname(), None);
        ///     Ok(())
        /// }
        /// ```
        #[stable(feature = "unix_socket", since = "1.10.0")]
        pub fn as_pathname(&self) -> Option<&Path> {
            if let AddressKind::Pathname(path) = self.address() { Some(path) } else { None }
        }

        fn address(&self) -> AddressKind<'_> {
            let len = self.len as usize - sun_path_offset(&self.addr);
            let path = unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&self.addr.sun_path) };

            // macOS seems to return a len of 16 and a zeroed sun_path for unnamed addresses
            if len == 0
                || (cfg!(not(any(target_os = "linux", target_os = "android")))
                    && self.addr.sun_path[0] == 0)
            {
                AddressKind::Unnamed
            } else if self.addr.sun_path[0] == 0 {
                AddressKind::Abstract(&path[1..len])
            } else {
                AddressKind::Pathname(OsStr::from_bytes(&path[..len - 1]).as_ref())
            }
        }
    }

    #[stable(feature = "unix_socket", since = "1.10.0")]
    impl fmt::Debug for SocketAddr {
        fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
            match self.address() {
                AddressKind::Unnamed => write!(fmt, "(unnamed)"),
                AddressKind::Abstract(name) => write!(fmt, "{} (abstract)", AsciiEscaped(name)),
                AddressKind::Pathname(path) => write!(fmt, "{:?} (pathname)", path),
            }
        }
    }