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

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

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