std/os/unix/net/
addr.rs

1use crate::bstr::ByteStr;
2use crate::ffi::OsStr;
3#[cfg(any(doc, target_os = "android", target_os = "linux", target_os = "cygwin"))]
4use crate::os::net::linux_ext;
5use crate::os::unix::ffi::OsStrExt;
6use crate::path::Path;
7use crate::sealed::Sealed;
8use crate::sys::cvt;
9use crate::{fmt, io, mem, ptr};
10
11// FIXME(#43348): Make libc adapt #[doc(cfg(...))] so we don't need these fake definitions here?
12#[cfg(not(unix))]
13#[allow(non_camel_case_types)]
14mod libc {
15    pub use core::ffi::c_int;
16    pub type socklen_t = u32;
17    pub struct sockaddr;
18    #[derive(Clone)]
19    pub struct sockaddr_un {
20        pub sun_path: [u8; 1],
21    }
22}
23
24const SUN_PATH_OFFSET: usize = mem::offset_of!(libc::sockaddr_un, sun_path);
25
26pub(super) fn sockaddr_un(path: &Path) -> io::Result<(libc::sockaddr_un, libc::socklen_t)> {
27    // SAFETY: All zeros is a valid representation for `sockaddr_un`.
28    let mut addr: libc::sockaddr_un = unsafe { mem::zeroed() };
29    addr.sun_family = libc::AF_UNIX as libc::sa_family_t;
30
31    let bytes = path.as_os_str().as_bytes();
32
33    if bytes.contains(&0) {
34        return Err(io::const_error!(
35            io::ErrorKind::InvalidInput,
36            "paths must not contain interior null bytes",
37        ));
38    }
39
40    if bytes.len() >= addr.sun_path.len() {
41        return Err(io::const_error!(
42            io::ErrorKind::InvalidInput,
43            "path must be shorter than SUN_LEN",
44        ));
45    }
46    // SAFETY: `bytes` and `addr.sun_path` are not overlapping and
47    // both point to valid memory.
48    // NOTE: We zeroed the memory above, so the path is already null
49    // terminated.
50    unsafe {
51        ptr::copy_nonoverlapping(bytes.as_ptr(), addr.sun_path.as_mut_ptr().cast(), bytes.len())
52    };
53
54    let mut len = SUN_PATH_OFFSET + bytes.len();
55    match bytes.get(0) {
56        Some(&0) | None => {}
57        Some(_) => len += 1,
58    }
59    Ok((addr, len as libc::socklen_t))
60}
61
62enum AddressKind<'a> {
63    Unnamed,
64    Pathname(&'a Path),
65    Abstract(&'a ByteStr),
66}
67
68/// An address associated with a Unix socket.
69///
70/// # Examples
71///
72/// ```
73/// use std::os::unix::net::UnixListener;
74///
75/// let socket = match UnixListener::bind("/tmp/sock") {
76///     Ok(sock) => sock,
77///     Err(e) => {
78///         println!("Couldn't bind: {e:?}");
79///         return
80///     }
81/// };
82/// let addr = socket.local_addr().expect("Couldn't get local address");
83/// ```
84#[derive(Clone)]
85#[stable(feature = "unix_socket", since = "1.10.0")]
86pub struct SocketAddr {
87    pub(super) addr: libc::sockaddr_un,
88    pub(super) len: libc::socklen_t,
89}
90
91impl SocketAddr {
92    pub(super) fn new<F>(f: F) -> io::Result<SocketAddr>
93    where
94        F: FnOnce(*mut libc::sockaddr, *mut libc::socklen_t) -> libc::c_int,
95    {
96        unsafe {
97            let mut addr: libc::sockaddr_un = mem::zeroed();
98            let mut len = size_of::<libc::sockaddr_un>() as libc::socklen_t;
99            cvt(f((&raw mut addr) as *mut _, &mut len))?;
100            SocketAddr::from_parts(addr, len)
101        }
102    }
103
104    pub(super) fn from_parts(
105        addr: libc::sockaddr_un,
106        mut len: libc::socklen_t,
107    ) -> io::Result<SocketAddr> {
108        if cfg!(target_os = "openbsd") {
109            // on OpenBSD, getsockname(2) returns the actual size of the socket address,
110            // and not the len of the content. Figure out the length for ourselves.
111            // https://marc.info/?l=openbsd-bugs&m=170105481926736&w=2
112            let sun_path: &[u8] =
113                unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&addr.sun_path) };
114            len = core::slice::memchr::memchr(0, sun_path)
115                .map_or(len, |new_len| (new_len + SUN_PATH_OFFSET) as libc::socklen_t);
116        }
117
118        if len == 0 {
119            // When there is a datagram from unnamed unix socket
120            // linux returns zero bytes of address
121            len = SUN_PATH_OFFSET as libc::socklen_t; // i.e., zero-length address
122        } else if addr.sun_family != libc::AF_UNIX as libc::sa_family_t {
123            return Err(io::const_error!(
124                io::ErrorKind::InvalidInput,
125                "file descriptor did not correspond to a Unix socket",
126            ));
127        }
128
129        Ok(SocketAddr { addr, len })
130    }
131
132    /// Constructs a `SockAddr` with the family `AF_UNIX` and the provided path.
133    ///
134    /// # Errors
135    ///
136    /// Returns an error if the path is longer than `SUN_LEN` or if it contains
137    /// NULL bytes.
138    ///
139    /// # Examples
140    ///
141    /// ```
142    /// use std::os::unix::net::SocketAddr;
143    /// use std::path::Path;
144    ///
145    /// # fn main() -> std::io::Result<()> {
146    /// let address = SocketAddr::from_pathname("/path/to/socket")?;
147    /// assert_eq!(address.as_pathname(), Some(Path::new("/path/to/socket")));
148    /// # Ok(())
149    /// # }
150    /// ```
151    ///
152    /// Creating a `SocketAddr` with a NULL byte results in an error.
153    ///
154    /// ```
155    /// use std::os::unix::net::SocketAddr;
156    ///
157    /// assert!(SocketAddr::from_pathname("/path/with/\0/bytes").is_err());
158    /// ```
159    #[stable(feature = "unix_socket_creation", since = "1.61.0")]
160    pub fn from_pathname<P>(path: P) -> io::Result<SocketAddr>
161    where
162        P: AsRef<Path>,
163    {
164        sockaddr_un(path.as_ref()).map(|(addr, len)| SocketAddr { addr, len })
165    }
166
167    /// Returns `true` if the address is unnamed.
168    ///
169    /// # Examples
170    ///
171    /// A named address:
172    ///
173    /// ```no_run
174    /// use std::os::unix::net::UnixListener;
175    ///
176    /// fn main() -> std::io::Result<()> {
177    ///     let socket = UnixListener::bind("/tmp/sock")?;
178    ///     let addr = socket.local_addr().expect("Couldn't get local address");
179    ///     assert_eq!(addr.is_unnamed(), false);
180    ///     Ok(())
181    /// }
182    /// ```
183    ///
184    /// An unnamed address:
185    ///
186    /// ```
187    /// use std::os::unix::net::UnixDatagram;
188    ///
189    /// fn main() -> std::io::Result<()> {
190    ///     let socket = UnixDatagram::unbound()?;
191    ///     let addr = socket.local_addr().expect("Couldn't get local address");
192    ///     assert_eq!(addr.is_unnamed(), true);
193    ///     Ok(())
194    /// }
195    /// ```
196    #[must_use]
197    #[stable(feature = "unix_socket", since = "1.10.0")]
198    pub fn is_unnamed(&self) -> bool {
199        matches!(self.address(), AddressKind::Unnamed)
200    }
201
202    /// Returns the contents of this address if it is a `pathname` address.
203    ///
204    /// # Examples
205    ///
206    /// With a pathname:
207    ///
208    /// ```no_run
209    /// use std::os::unix::net::UnixListener;
210    /// use std::path::Path;
211    ///
212    /// fn main() -> std::io::Result<()> {
213    ///     let socket = UnixListener::bind("/tmp/sock")?;
214    ///     let addr = socket.local_addr().expect("Couldn't get local address");
215    ///     assert_eq!(addr.as_pathname(), Some(Path::new("/tmp/sock")));
216    ///     Ok(())
217    /// }
218    /// ```
219    ///
220    /// Without a pathname:
221    ///
222    /// ```
223    /// use std::os::unix::net::UnixDatagram;
224    ///
225    /// fn main() -> std::io::Result<()> {
226    ///     let socket = UnixDatagram::unbound()?;
227    ///     let addr = socket.local_addr().expect("Couldn't get local address");
228    ///     assert_eq!(addr.as_pathname(), None);
229    ///     Ok(())
230    /// }
231    /// ```
232    #[stable(feature = "unix_socket", since = "1.10.0")]
233    #[must_use]
234    pub fn as_pathname(&self) -> Option<&Path> {
235        if let AddressKind::Pathname(path) = self.address() { Some(path) } else { None }
236    }
237
238    fn address(&self) -> AddressKind<'_> {
239        let len = self.len as usize - SUN_PATH_OFFSET;
240        let path = unsafe { mem::transmute::<&[libc::c_char], &[u8]>(&self.addr.sun_path) };
241
242        // macOS seems to return a len of 16 and a zeroed sun_path for unnamed addresses
243        if len == 0
244            || (cfg!(not(any(target_os = "linux", target_os = "android", target_os = "cygwin")))
245                && self.addr.sun_path[0] == 0)
246        {
247            AddressKind::Unnamed
248        } else if self.addr.sun_path[0] == 0 {
249            AddressKind::Abstract(ByteStr::from_bytes(&path[1..len]))
250        } else {
251            AddressKind::Pathname(OsStr::from_bytes(&path[..len - 1]).as_ref())
252        }
253    }
254}
255
256#[stable(feature = "unix_socket_abstract", since = "1.70.0")]
257impl Sealed for SocketAddr {}
258
259#[doc(cfg(any(target_os = "android", target_os = "linux", target_os = "cygwin")))]
260#[cfg(any(doc, target_os = "android", target_os = "linux", target_os = "cygwin"))]
261#[stable(feature = "unix_socket_abstract", since = "1.70.0")]
262impl linux_ext::addr::SocketAddrExt for SocketAddr {
263    fn as_abstract_name(&self) -> Option<&[u8]> {
264        if let AddressKind::Abstract(name) = self.address() { Some(name.as_bytes()) } else { None }
265    }
266
267    fn from_abstract_name<N>(name: N) -> crate::io::Result<Self>
268    where
269        N: AsRef<[u8]>,
270    {
271        let name = name.as_ref();
272        unsafe {
273            let mut addr: libc::sockaddr_un = mem::zeroed();
274            addr.sun_family = libc::AF_UNIX as libc::sa_family_t;
275
276            if name.len() + 1 > addr.sun_path.len() {
277                return Err(io::const_error!(
278                    io::ErrorKind::InvalidInput,
279                    "abstract socket name must be shorter than SUN_LEN",
280                ));
281            }
282
283            crate::ptr::copy_nonoverlapping(
284                name.as_ptr(),
285                addr.sun_path.as_mut_ptr().add(1) as *mut u8,
286                name.len(),
287            );
288            let len = (SUN_PATH_OFFSET + 1 + name.len()) as libc::socklen_t;
289            SocketAddr::from_parts(addr, len)
290        }
291    }
292}
293
294#[stable(feature = "unix_socket", since = "1.10.0")]
295impl fmt::Debug for SocketAddr {
296    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
297        match self.address() {
298            AddressKind::Unnamed => write!(fmt, "(unnamed)"),
299            AddressKind::Abstract(name) => write!(fmt, "{name:?} (abstract)"),
300            AddressKind::Pathname(path) => write!(fmt, "{path:?} (pathname)"),
301        }
302    }
303}
std/os/unix/net/addr.rs

std/os/unix/net/
addr.rs
