std/sys/net/connection/socket/
unix.rs

1use libc::{MSG_PEEK, c_int, c_void, size_t, sockaddr, socklen_t};
2
3#[cfg(not(any(target_os = "espidf", target_os = "nuttx")))]
4use crate::ffi::CStr;
5use crate::io::{self, BorrowedBuf, BorrowedCursor, IoSlice, IoSliceMut};
6use crate::net::{Shutdown, SocketAddr};
7use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
8use crate::sys::fd::FileDesc;
9use crate::sys::net::{getsockopt, setsockopt};
10use crate::sys::pal::IsMinusOne;
11use crate::sys_common::{AsInner, FromInner, IntoInner};
12use crate::time::{Duration, Instant};
13use crate::{cmp, mem};
14
15cfg_if::cfg_if! {
16    if #[cfg(target_vendor = "apple")] {
17        use libc::SO_LINGER_SEC as SO_LINGER;
18    } else {
19        use libc::SO_LINGER;
20    }
21}
22
23pub(super) use libc as netc;
24
25use super::{socket_addr_from_c, socket_addr_to_c};
26pub use crate::sys::{cvt, cvt_r};
27
28#[expect(non_camel_case_types)]
29pub type wrlen_t = size_t;
30
31pub struct Socket(FileDesc);
32
33pub fn init() {}
34
35pub fn cvt_gai(err: c_int) -> io::Result<()> {
36    if err == 0 {
37        return Ok(());
38    }
39
40    // We may need to trigger a glibc workaround. See on_resolver_failure() for details.
41    on_resolver_failure();
42
43    #[cfg(not(any(target_os = "espidf", target_os = "nuttx")))]
44    if err == libc::EAI_SYSTEM {
45        return Err(io::Error::last_os_error());
46    }
47
48    #[cfg(not(any(target_os = "espidf", target_os = "nuttx")))]
49    let detail = unsafe {
50        // We can't always expect a UTF-8 environment. When we don't get that luxury,
51        // it's better to give a low-quality error message than none at all.
52        CStr::from_ptr(libc::gai_strerror(err)).to_string_lossy()
53    };
54
55    #[cfg(any(target_os = "espidf", target_os = "nuttx"))]
56    let detail = "";
57
58    Err(io::Error::new(
59        io::ErrorKind::Uncategorized,
60        &format!("failed to lookup address information: {detail}")[..],
61    ))
62}
63
64impl Socket {
65    pub fn new(addr: &SocketAddr, ty: c_int) -> io::Result<Socket> {
66        let fam = match *addr {
67            SocketAddr::V4(..) => libc::AF_INET,
68            SocketAddr::V6(..) => libc::AF_INET6,
69        };
70        Socket::new_raw(fam, ty)
71    }
72
73    pub fn new_raw(fam: c_int, ty: c_int) -> io::Result<Socket> {
74        unsafe {
75            cfg_if::cfg_if! {
76                if #[cfg(any(
77                    target_os = "android",
78                    target_os = "dragonfly",
79                    target_os = "freebsd",
80                    target_os = "illumos",
81                    target_os = "hurd",
82                    target_os = "linux",
83                    target_os = "netbsd",
84                    target_os = "openbsd",
85                    target_os = "cygwin",
86                    target_os = "nto",
87                    target_os = "solaris",
88                ))] {
89                    // On platforms that support it we pass the SOCK_CLOEXEC
90                    // flag to atomically create the socket and set it as
91                    // CLOEXEC. On Linux this was added in 2.6.27.
92                    let fd = cvt(libc::socket(fam, ty | libc::SOCK_CLOEXEC, 0))?;
93                    let socket = Socket(FileDesc::from_raw_fd(fd));
94
95                    // DragonFlyBSD, FreeBSD and NetBSD use `SO_NOSIGPIPE` as a `setsockopt`
96                    // flag to disable `SIGPIPE` emission on socket.
97                    #[cfg(any(target_os = "freebsd", target_os = "netbsd", target_os = "dragonfly"))]
98                    setsockopt(&socket, libc::SOL_SOCKET, libc::SO_NOSIGPIPE, 1)?;
99
100                    Ok(socket)
101                } else {
102                    let fd = cvt(libc::socket(fam, ty, 0))?;
103                    let fd = FileDesc::from_raw_fd(fd);
104                    fd.set_cloexec()?;
105                    let socket = Socket(fd);
106
107                    // macOS and iOS use `SO_NOSIGPIPE` as a `setsockopt`
108                    // flag to disable `SIGPIPE` emission on socket.
109                    #[cfg(target_vendor = "apple")]
110                    setsockopt(&socket, libc::SOL_SOCKET, libc::SO_NOSIGPIPE, 1)?;
111
112                    Ok(socket)
113                }
114            }
115        }
116    }
117
118    #[cfg(not(target_os = "vxworks"))]
119    pub fn new_pair(fam: c_int, ty: c_int) -> io::Result<(Socket, Socket)> {
120        unsafe {
121            let mut fds = [0, 0];
122
123            cfg_if::cfg_if! {
124                if #[cfg(any(
125                    target_os = "android",
126                    target_os = "dragonfly",
127                    target_os = "freebsd",
128                    target_os = "illumos",
129                    target_os = "linux",
130                    target_os = "hurd",
131                    target_os = "netbsd",
132                    target_os = "openbsd",
133                    target_os = "cygwin",
134                    target_os = "nto",
135                ))] {
136                    // Like above, set cloexec atomically
137                    cvt(libc::socketpair(fam, ty | libc::SOCK_CLOEXEC, 0, fds.as_mut_ptr()))?;
138                    Ok((Socket(FileDesc::from_raw_fd(fds[0])), Socket(FileDesc::from_raw_fd(fds[1]))))
139                } else {
140                    cvt(libc::socketpair(fam, ty, 0, fds.as_mut_ptr()))?;
141                    let a = FileDesc::from_raw_fd(fds[0]);
142                    let b = FileDesc::from_raw_fd(fds[1]);
143                    a.set_cloexec()?;
144                    b.set_cloexec()?;
145                    Ok((Socket(a), Socket(b)))
146                }
147            }
148        }
149    }
150
151    #[cfg(target_os = "vxworks")]
152    pub fn new_pair(_fam: c_int, _ty: c_int) -> io::Result<(Socket, Socket)> {
153        unimplemented!()
154    }
155
156    pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
157        let (addr, len) = socket_addr_to_c(addr);
158        loop {
159            let result = unsafe { libc::connect(self.as_raw_fd(), addr.as_ptr(), len) };
160            if result.is_minus_one() {
161                let err = crate::sys::os::errno();
162                match err {
163                    libc::EINTR => continue,
164                    libc::EISCONN => return Ok(()),
165                    _ => return Err(io::Error::from_raw_os_error(err)),
166                }
167            }
168            return Ok(());
169        }
170    }
171
172    pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
173        self.set_nonblocking(true)?;
174        let r = unsafe {
175            let (addr, len) = socket_addr_to_c(addr);
176            cvt(libc::connect(self.as_raw_fd(), addr.as_ptr(), len))
177        };
178        self.set_nonblocking(false)?;
179
180        match r {
181            Ok(_) => return Ok(()),
182            // there's no ErrorKind for EINPROGRESS :(
183            Err(ref e) if e.raw_os_error() == Some(libc::EINPROGRESS) => {}
184            Err(e) => return Err(e),
185        }
186
187        let mut pollfd = libc::pollfd { fd: self.as_raw_fd(), events: libc::POLLOUT, revents: 0 };
188
189        if timeout.as_secs() == 0 && timeout.subsec_nanos() == 0 {
190            return Err(io::Error::ZERO_TIMEOUT);
191        }
192
193        let start = Instant::now();
194
195        loop {
196            let elapsed = start.elapsed();
197            if elapsed >= timeout {
198                return Err(io::const_error!(io::ErrorKind::TimedOut, "connection timed out"));
199            }
200
201            let timeout = timeout - elapsed;
202            let mut timeout = timeout
203                .as_secs()
204                .saturating_mul(1_000)
205                .saturating_add(timeout.subsec_nanos() as u64 / 1_000_000);
206            if timeout == 0 {
207                timeout = 1;
208            }
209
210            let timeout = cmp::min(timeout, c_int::MAX as u64) as c_int;
211
212            match unsafe { libc::poll(&mut pollfd, 1, timeout) } {
213                -1 => {
214                    let err = io::Error::last_os_error();
215                    if !err.is_interrupted() {
216                        return Err(err);
217                    }
218                }
219                0 => {}
220                _ => {
221                    if cfg!(target_os = "vxworks") {
222                        // VxWorks poll does not return  POLLHUP or POLLERR in revents. Check if the
223                        // connection actually succeeded and return ok only when the socket is
224                        // ready and no errors were found.
225                        if let Some(e) = self.take_error()? {
226                            return Err(e);
227                        }
228                    } else {
229                        // linux returns POLLOUT|POLLERR|POLLHUP for refused connections (!), so look
230                        // for POLLHUP or POLLERR rather than read readiness
231                        if pollfd.revents & (libc::POLLHUP | libc::POLLERR) != 0 {
232                            let e = self.take_error()?.unwrap_or_else(|| {
233                                io::const_error!(
234                                    io::ErrorKind::Uncategorized,
235                                    "no error set after POLLHUP",
236                                )
237                            });
238                            return Err(e);
239                        }
240                    }
241
242                    return Ok(());
243                }
244            }
245        }
246    }
247
248    pub fn accept(&self, storage: *mut sockaddr, len: *mut socklen_t) -> io::Result<Socket> {
249        // Unfortunately the only known way right now to accept a socket and
250        // atomically set the CLOEXEC flag is to use the `accept4` syscall on
251        // platforms that support it. On Linux, this was added in 2.6.28,
252        // glibc 2.10 and musl 0.9.5.
253        cfg_if::cfg_if! {
254            if #[cfg(any(
255                target_os = "android",
256                target_os = "dragonfly",
257                target_os = "freebsd",
258                target_os = "illumos",
259                target_os = "linux",
260                target_os = "hurd",
261                target_os = "netbsd",
262                target_os = "openbsd",
263                target_os = "cygwin",
264            ))] {
265                unsafe {
266                    let fd = cvt_r(|| libc::accept4(self.as_raw_fd(), storage, len, libc::SOCK_CLOEXEC))?;
267                    Ok(Socket(FileDesc::from_raw_fd(fd)))
268                }
269            } else {
270                unsafe {
271                    let fd = cvt_r(|| libc::accept(self.as_raw_fd(), storage, len))?;
272                    let fd = FileDesc::from_raw_fd(fd);
273                    fd.set_cloexec()?;
274                    Ok(Socket(fd))
275                }
276            }
277        }
278    }
279
280    pub fn duplicate(&self) -> io::Result<Socket> {
281        self.0.duplicate().map(Socket)
282    }
283
284    fn recv_with_flags(&self, mut buf: BorrowedCursor<'_>, flags: c_int) -> io::Result<()> {
285        let ret = cvt(unsafe {
286            libc::recv(
287                self.as_raw_fd(),
288                buf.as_mut().as_mut_ptr() as *mut c_void,
289                buf.capacity(),
290                flags,
291            )
292        })?;
293        unsafe {
294            buf.advance_unchecked(ret as usize);
295        }
296        Ok(())
297    }
298
299    pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
300        let mut buf = BorrowedBuf::from(buf);
301        self.recv_with_flags(buf.unfilled(), 0)?;
302        Ok(buf.len())
303    }
304
305    pub fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
306        let mut buf = BorrowedBuf::from(buf);
307        self.recv_with_flags(buf.unfilled(), MSG_PEEK)?;
308        Ok(buf.len())
309    }
310
311    pub fn read_buf(&self, buf: BorrowedCursor<'_>) -> io::Result<()> {
312        self.recv_with_flags(buf, 0)
313    }
314
315    pub fn read_vectored(&self, bufs: &mut [IoSliceMut<'_>]) -> io::Result<usize> {
316        self.0.read_vectored(bufs)
317    }
318
319    #[inline]
320    pub fn is_read_vectored(&self) -> bool {
321        self.0.is_read_vectored()
322    }
323
324    fn recv_from_with_flags(
325        &self,
326        buf: &mut [u8],
327        flags: c_int,
328    ) -> io::Result<(usize, SocketAddr)> {
329        // The `recvfrom` function will fill in the storage with the address,
330        // so we don't need to zero it here.
331        // reference: https://linux.die.net/man/2/recvfrom
332        let mut storage: mem::MaybeUninit<libc::sockaddr_storage> = mem::MaybeUninit::uninit();
333        let mut addrlen = size_of_val(&storage) as libc::socklen_t;
334
335        let n = cvt(unsafe {
336            libc::recvfrom(
337                self.as_raw_fd(),
338                buf.as_mut_ptr() as *mut c_void,
339                buf.len(),
340                flags,
341                (&raw mut storage) as *mut _,
342                &mut addrlen,
343            )
344        })?;
345        Ok((n as usize, unsafe { socket_addr_from_c(storage.as_ptr(), addrlen as usize)? }))
346    }
347
348    pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
349        self.recv_from_with_flags(buf, 0)
350    }
351
352    #[cfg(any(target_os = "android", target_os = "linux"))]
353    pub fn recv_msg(&self, msg: &mut libc::msghdr) -> io::Result<usize> {
354        let n = cvt(unsafe { libc::recvmsg(self.as_raw_fd(), msg, libc::MSG_CMSG_CLOEXEC) })?;
355        Ok(n as usize)
356    }
357
358    pub fn peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
359        self.recv_from_with_flags(buf, MSG_PEEK)
360    }
361
362    pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
363        self.0.write(buf)
364    }
365
366    pub fn write_vectored(&self, bufs: &[IoSlice<'_>]) -> io::Result<usize> {
367        self.0.write_vectored(bufs)
368    }
369
370    #[inline]
371    pub fn is_write_vectored(&self) -> bool {
372        self.0.is_write_vectored()
373    }
374
375    #[cfg(any(target_os = "android", target_os = "linux"))]
376    pub fn send_msg(&self, msg: &mut libc::msghdr) -> io::Result<usize> {
377        let n = cvt(unsafe { libc::sendmsg(self.as_raw_fd(), msg, 0) })?;
378        Ok(n as usize)
379    }
380
381    pub fn set_timeout(&self, dur: Option<Duration>, kind: libc::c_int) -> io::Result<()> {
382        let timeout = match dur {
383            Some(dur) => {
384                if dur.as_secs() == 0 && dur.subsec_nanos() == 0 {
385                    return Err(io::Error::ZERO_TIMEOUT);
386                }
387
388                let secs = if dur.as_secs() > libc::time_t::MAX as u64 {
389                    libc::time_t::MAX
390                } else {
391                    dur.as_secs() as libc::time_t
392                };
393                let mut timeout = libc::timeval {
394                    tv_sec: secs,
395                    tv_usec: dur.subsec_micros() as libc::suseconds_t,
396                };
397                if timeout.tv_sec == 0 && timeout.tv_usec == 0 {
398                    timeout.tv_usec = 1;
399                }
400                timeout
401            }
402            None => libc::timeval { tv_sec: 0, tv_usec: 0 },
403        };
404        setsockopt(self, libc::SOL_SOCKET, kind, timeout)
405    }
406
407    pub fn timeout(&self, kind: libc::c_int) -> io::Result<Option<Duration>> {
408        let raw: libc::timeval = getsockopt(self, libc::SOL_SOCKET, kind)?;
409        if raw.tv_sec == 0 && raw.tv_usec == 0 {
410            Ok(None)
411        } else {
412            let sec = raw.tv_sec as u64;
413            let nsec = (raw.tv_usec as u32) * 1000;
414            Ok(Some(Duration::new(sec, nsec)))
415        }
416    }
417
418    pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
419        let how = match how {
420            Shutdown::Write => libc::SHUT_WR,
421            Shutdown::Read => libc::SHUT_RD,
422            Shutdown::Both => libc::SHUT_RDWR,
423        };
424        cvt(unsafe { libc::shutdown(self.as_raw_fd(), how) })?;
425        Ok(())
426    }
427
428    #[cfg(not(target_os = "cygwin"))]
429    pub fn set_linger(&self, linger: Option<Duration>) -> io::Result<()> {
430        let linger = libc::linger {
431            l_onoff: linger.is_some() as libc::c_int,
432            l_linger: linger.unwrap_or_default().as_secs() as libc::c_int,
433        };
434
435        setsockopt(self, libc::SOL_SOCKET, SO_LINGER, linger)
436    }
437
438    #[cfg(target_os = "cygwin")]
439    pub fn set_linger(&self, linger: Option<Duration>) -> io::Result<()> {
440        let linger = libc::linger {
441            l_onoff: linger.is_some() as libc::c_ushort,
442            l_linger: linger.unwrap_or_default().as_secs() as libc::c_ushort,
443        };
444
445        setsockopt(self, libc::SOL_SOCKET, SO_LINGER, linger)
446    }
447
448    pub fn linger(&self) -> io::Result<Option<Duration>> {
449        let val: libc::linger = getsockopt(self, libc::SOL_SOCKET, SO_LINGER)?;
450
451        Ok((val.l_onoff != 0).then(|| Duration::from_secs(val.l_linger as u64)))
452    }
453
454    pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
455        setsockopt(self, libc::IPPROTO_TCP, libc::TCP_NODELAY, nodelay as c_int)
456    }
457
458    pub fn nodelay(&self) -> io::Result<bool> {
459        let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_NODELAY)?;
460        Ok(raw != 0)
461    }
462
463    #[cfg(any(target_os = "android", target_os = "linux",))]
464    pub fn set_quickack(&self, quickack: bool) -> io::Result<()> {
465        setsockopt(self, libc::IPPROTO_TCP, libc::TCP_QUICKACK, quickack as c_int)
466    }
467
468    #[cfg(any(target_os = "android", target_os = "linux",))]
469    pub fn quickack(&self) -> io::Result<bool> {
470        let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_QUICKACK)?;
471        Ok(raw != 0)
472    }
473
474    // bionic libc makes no use of this flag
475    #[cfg(target_os = "linux")]
476    pub fn set_deferaccept(&self, accept: u32) -> io::Result<()> {
477        setsockopt(self, libc::IPPROTO_TCP, libc::TCP_DEFER_ACCEPT, accept as c_int)
478    }
479
480    #[cfg(target_os = "linux")]
481    pub fn deferaccept(&self) -> io::Result<u32> {
482        let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_DEFER_ACCEPT)?;
483        Ok(raw as u32)
484    }
485
486    #[cfg(any(target_os = "freebsd", target_os = "netbsd"))]
487    pub fn set_acceptfilter(&self, name: &CStr) -> io::Result<()> {
488        if !name.to_bytes().is_empty() {
489            const AF_NAME_MAX: usize = 16;
490            let mut buf = [0; AF_NAME_MAX];
491            for (src, dst) in name.to_bytes().iter().zip(&mut buf[..AF_NAME_MAX - 1]) {
492                *dst = *src as libc::c_char;
493            }
494            let mut arg: libc::accept_filter_arg = unsafe { mem::zeroed() };
495            arg.af_name = buf;
496            setsockopt(self, libc::SOL_SOCKET, libc::SO_ACCEPTFILTER, &mut arg)
497        } else {
498            setsockopt(
499                self,
500                libc::SOL_SOCKET,
501                libc::SO_ACCEPTFILTER,
502                core::ptr::null_mut() as *mut c_void,
503            )
504        }
505    }
506
507    #[cfg(any(target_os = "freebsd", target_os = "netbsd"))]
508    pub fn acceptfilter(&self) -> io::Result<&CStr> {
509        let arg: libc::accept_filter_arg =
510            getsockopt(self, libc::SOL_SOCKET, libc::SO_ACCEPTFILTER)?;
511        let s: &[u8] =
512            unsafe { core::slice::from_raw_parts(arg.af_name.as_ptr() as *const u8, 16) };
513        let name = CStr::from_bytes_with_nul(s).unwrap();
514        Ok(name)
515    }
516
517    #[cfg(any(target_os = "android", target_os = "linux",))]
518    pub fn set_passcred(&self, passcred: bool) -> io::Result<()> {
519        setsockopt(self, libc::SOL_SOCKET, libc::SO_PASSCRED, passcred as libc::c_int)
520    }
521
522    #[cfg(any(target_os = "android", target_os = "linux",))]
523    pub fn passcred(&self) -> io::Result<bool> {
524        let passcred: libc::c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_PASSCRED)?;
525        Ok(passcred != 0)
526    }
527
528    #[cfg(target_os = "netbsd")]
529    pub fn set_local_creds(&self, local_creds: bool) -> io::Result<()> {
530        setsockopt(self, 0 as libc::c_int, libc::LOCAL_CREDS, local_creds as libc::c_int)
531    }
532
533    #[cfg(target_os = "netbsd")]
534    pub fn local_creds(&self) -> io::Result<bool> {
535        let local_creds: libc::c_int = getsockopt(self, 0 as libc::c_int, libc::LOCAL_CREDS)?;
536        Ok(local_creds != 0)
537    }
538
539    #[cfg(target_os = "freebsd")]
540    pub fn set_local_creds_persistent(&self, local_creds_persistent: bool) -> io::Result<()> {
541        setsockopt(
542            self,
543            libc::AF_LOCAL,
544            libc::LOCAL_CREDS_PERSISTENT,
545            local_creds_persistent as libc::c_int,
546        )
547    }
548
549    #[cfg(target_os = "freebsd")]
550    pub fn local_creds_persistent(&self) -> io::Result<bool> {
551        let local_creds_persistent: libc::c_int =
552            getsockopt(self, libc::AF_LOCAL, libc::LOCAL_CREDS_PERSISTENT)?;
553        Ok(local_creds_persistent != 0)
554    }
555
556    #[cfg(not(any(target_os = "solaris", target_os = "illumos", target_os = "vita")))]
557    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
558        let mut nonblocking = nonblocking as libc::c_int;
559        cvt(unsafe { libc::ioctl(self.as_raw_fd(), libc::FIONBIO, &mut nonblocking) }).map(drop)
560    }
561
562    #[cfg(target_os = "vita")]
563    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
564        let option = nonblocking as libc::c_int;
565        setsockopt(self, libc::SOL_SOCKET, libc::SO_NONBLOCK, option)
566    }
567
568    #[cfg(any(target_os = "solaris", target_os = "illumos"))]
569    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
570        // FIONBIO is inadequate for sockets on illumos/Solaris, so use the
571        // fcntl(F_[GS]ETFL)-based method provided by FileDesc instead.
572        self.0.set_nonblocking(nonblocking)
573    }
574
575    #[cfg(any(target_os = "linux", target_os = "freebsd", target_os = "openbsd"))]
576    pub fn set_mark(&self, mark: u32) -> io::Result<()> {
577        #[cfg(target_os = "linux")]
578        let option = libc::SO_MARK;
579        #[cfg(target_os = "freebsd")]
580        let option = libc::SO_USER_COOKIE;
581        #[cfg(target_os = "openbsd")]
582        let option = libc::SO_RTABLE;
583        setsockopt(self, libc::SOL_SOCKET, option, mark as libc::c_int)
584    }
585
586    pub fn take_error(&self) -> io::Result<Option<io::Error>> {
587        let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
588        if raw == 0 { Ok(None) } else { Ok(Some(io::Error::from_raw_os_error(raw as i32))) }
589    }
590
591    // This is used by sys_common code to abstract over Windows and Unix.
592    pub fn as_raw(&self) -> RawFd {
593        self.as_raw_fd()
594    }
595}
596
597impl AsInner<FileDesc> for Socket {
598    #[inline]
599    fn as_inner(&self) -> &FileDesc {
600        &self.0
601    }
602}
603
604impl IntoInner<FileDesc> for Socket {
605    fn into_inner(self) -> FileDesc {
606        self.0
607    }
608}
609
610impl FromInner<FileDesc> for Socket {
611    fn from_inner(file_desc: FileDesc) -> Self {
612        Self(file_desc)
613    }
614}
615
616impl AsFd for Socket {
617    fn as_fd(&self) -> BorrowedFd<'_> {
618        self.0.as_fd()
619    }
620}
621
622impl AsRawFd for Socket {
623    #[inline]
624    fn as_raw_fd(&self) -> RawFd {
625        self.0.as_raw_fd()
626    }
627}
628
629impl IntoRawFd for Socket {
630    fn into_raw_fd(self) -> RawFd {
631        self.0.into_raw_fd()
632    }
633}
634
635impl FromRawFd for Socket {
636    unsafe fn from_raw_fd(raw_fd: RawFd) -> Self {
637        Self(FromRawFd::from_raw_fd(raw_fd))
638    }
639}
640
641// In versions of glibc prior to 2.26, there's a bug where the DNS resolver
642// will cache the contents of /etc/resolv.conf, so changes to that file on disk
643// can be ignored by a long-running program. That can break DNS lookups on e.g.
644// laptops where the network comes and goes. See
645// https://sourceware.org/bugzilla/show_bug.cgi?id=984. Note however that some
646// distros including Debian have patched glibc to fix this for a long time.
647//
648// A workaround for this bug is to call the res_init libc function, to clear
649// the cached configs. Unfortunately, while we believe glibc's implementation
650// of res_init is thread-safe, we know that other implementations are not
651// (https://github.com/rust-lang/rust/issues/43592). Code here in std could
652// try to synchronize its res_init calls with a Mutex, but that wouldn't
653// protect programs that call into libc in other ways. So instead of calling
654// res_init unconditionally, we call it only when we detect we're linking
655// against glibc version < 2.26. (That is, when we both know its needed and
656// believe it's thread-safe).
657#[cfg(all(target_os = "linux", target_env = "gnu"))]
658fn on_resolver_failure() {
659    use crate::sys;
660
661    // If the version fails to parse, we treat it the same as "not glibc".
662    if let Some(version) = sys::os::glibc_version() {
663        if version < (2, 26) {
664            unsafe { libc::res_init() };
665        }
666    }
667}
668
669#[cfg(not(all(target_os = "linux", target_env = "gnu")))]
670fn on_resolver_failure() {}
std/sys/net/connection/socket/unix.rs

std/sys/net/connection/socket/
unix.rs
