src/libstd/sys/unix/net.rs

   1 // Copyright 2015 The Rust Project Developers. See the COPYRIGHT
   2 // file at the top-level directory of this distribution and at
   3 // http://rust-lang.org/COPYRIGHT.
   4 //
   5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
   6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
   7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
   8 // option. This file may not be copied, modified, or distributed
   9 // except according to those terms.
  10
  11 use ffi::CStr;
  12 use io;
  13 use libc::{self, c_int, c_void, size_t, sockaddr, socklen_t, EAI_SYSTEM, MSG_PEEK};
  14 use mem;
  15 use net::{SocketAddr, Shutdown};
  16 use str;
  17 use sys::fd::FileDesc;
  18 use sys_common::{AsInner, FromInner, IntoInner};
  19 use sys_common::net::{getsockopt, setsockopt, sockaddr_to_addr};
  20 use time::{Duration, Instant};
  21 use cmp;
  22
  23 pub use sys::{cvt, cvt_r};
  24 pub extern crate libc as netc;
  25
  26 pub type wrlen_t = size_t;
  27
  28 // See below for the usage of SOCK_CLOEXEC, but this constant is only defined on
  29 // Linux currently (e.g. support doesn't exist on other platforms). In order to
  30 // get name resolution to work and things to compile we just define a dummy
  31 // SOCK_CLOEXEC here for other platforms. Note that the dummy constant isn't
  32 // actually ever used (the blocks below are wrapped in `if cfg!` as well.
  33 #[cfg(target_os = "linux")]
  34 use libc::SOCK_CLOEXEC;
  35 #[cfg(not(target_os = "linux"))]
  36 const SOCK_CLOEXEC: c_int = 0;
  37
  38 // Another conditional contant for name resolution: Macos et iOS use
  39 // SO_NOSIGPIPE as a setsockopt flag to disable SIGPIPE emission on socket.
  40 // Other platforms do otherwise.
  41 #[cfg(target_vendor = "apple")]
  42 use libc::SO_NOSIGPIPE;
  43 #[cfg(not(target_vendor = "apple"))]
  44 const SO_NOSIGPIPE: c_int = 0;
  45
  46 pub struct Socket(FileDesc);
  47
  48 pub fn init() {}
  49
  50 pub fn cvt_gai(err: c_int) -> io::Result<()> {
  51     if err == 0 {
  52         return Ok(())
  53     }
  54     if err == EAI_SYSTEM {
  55         return Err(io::Error::last_os_error())
  56     }
  57
  58     let detail = unsafe {
  59         str::from_utf8(CStr::from_ptr(libc::gai_strerror(err)).to_bytes()).unwrap()
  60             .to_owned()
  61     };
  62     Err(io::Error::new(io::ErrorKind::Other,
  63                        &format!("failed to lookup address information: {}",
  64                                 detail)[..]))
  65 }
  66
  67 impl Socket {
  68     pub fn new(addr: &SocketAddr, ty: c_int) -> io::Result<Socket> {
  69         let fam = match *addr {
  70             SocketAddr::V4(..) => libc::AF_INET,
  71             SocketAddr::V6(..) => libc::AF_INET6,
  72         };
  73         Socket::new_raw(fam, ty)
  74     }
  75
  76     pub fn new_raw(fam: c_int, ty: c_int) -> io::Result<Socket> {
  77         unsafe {
  78             // On linux we first attempt to pass the SOCK_CLOEXEC flag to
  79             // atomically create the socket and set it as CLOEXEC. Support for
  80             // this option, however, was added in 2.6.27, and we still support
  81             // 2.6.18 as a kernel, so if the returned error is EINVAL we
  82             // fallthrough to the fallback.
  83             if cfg!(target_os = "linux") {
  84                 match cvt(libc::socket(fam, ty | SOCK_CLOEXEC, 0)) {
  85                     Ok(fd) => return Ok(Socket(FileDesc::new(fd))),
  86                     Err(ref e) if e.raw_os_error() == Some(libc::EINVAL) => {}
  87                     Err(e) => return Err(e),
  88                 }
  89             }
  90
  91             let fd = cvt(libc::socket(fam, ty, 0))?;
  92             let fd = FileDesc::new(fd);
  93             fd.set_cloexec()?;
  94             let socket = Socket(fd);
  95             if cfg!(target_vendor = "apple") {
  96                 setsockopt(&socket, libc::SOL_SOCKET, SO_NOSIGPIPE, 1)?;
  97             }
  98             Ok(socket)
  99         }
 100     }
 101
 102     pub fn new_pair(fam: c_int, ty: c_int) -> io::Result<(Socket, Socket)> {
 103         unsafe {
 104             let mut fds = [0, 0];
 105
 106             // Like above, see if we can set cloexec atomically
 107             if cfg!(target_os = "linux") {
 108                 match cvt(libc::socketpair(fam, ty | SOCK_CLOEXEC, 0, fds.as_mut_ptr())) {
 109                     Ok(_) => {
 110                         return Ok((Socket(FileDesc::new(fds[0])), Socket(FileDesc::new(fds[1]))));
 111                     }
 112                     Err(ref e) if e.raw_os_error() == Some(libc::EINVAL) => {},
 113                     Err(e) => return Err(e),
 114                 }
 115             }
 116
 117             cvt(libc::socketpair(fam, ty, 0, fds.as_mut_ptr()))?;
 118             let a = FileDesc::new(fds[0]);
 119             let b = FileDesc::new(fds[1]);
 120             a.set_cloexec()?;
 121             b.set_cloexec()?;
 122             Ok((Socket(a), Socket(b)))
 123         }
 124     }
 125
 126     pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
 127         self.set_nonblocking(true)?;
 128         let r = unsafe {
 129             let (addrp, len) = addr.into_inner();
 130             cvt(libc::connect(self.0.raw(), addrp, len))
 131         };
 132         self.set_nonblocking(false)?;
 133
 134         match r {
 135             Ok(_) => return Ok(()),
 136             // there's no ErrorKind for EINPROGRESS :(
 137             Err(ref e) if e.raw_os_error() == Some(libc::EINPROGRESS) => {}
 138             Err(e) => return Err(e),
 139         }
 140
 141         let mut pollfd = libc::pollfd {
 142             fd: self.0.raw(),
 143             events: libc::POLLOUT,
 144             revents: 0,
 145         };
 146
 147         if timeout.as_secs() == 0 && timeout.subsec_nanos() == 0 {
 148             return Err(io::Error::new(io::ErrorKind::InvalidInput,
 149                                       "cannot set a 0 duration timeout"));
 150         }
 151
 152         let start = Instant::now();
 153
 154         loop {
 155             let elapsed = start.elapsed();
 156             if elapsed >= timeout {
 157                 return Err(io::Error::new(io::ErrorKind::TimedOut, "connection timed out"));
 158             }
 159
 160             let timeout = timeout - elapsed;
 161             let mut timeout = timeout.as_secs()
 162                 .saturating_mul(1_000)
 163                 .saturating_add(timeout.subsec_nanos() as u64 / 1_000_000);
 164             if timeout == 0 {
 165                 timeout = 1;
 166             }
 167
 168             let timeout = cmp::min(timeout, c_int::max_value() as u64) as c_int;
 169
 170             match unsafe { libc::poll(&mut pollfd, 1, timeout) } {
 171                 -1 => {
 172                     let err = io::Error::last_os_error();
 173                     if err.kind() != io::ErrorKind::Interrupted {
 174                         return Err(err);
 175                     }
 176                 }
 177                 0 => {}
 178                 _ => {
 179                     // linux returns POLLOUT|POLLERR|POLLHUP for refused connections (!), so look
 180                     // for POLLHUP rather than read readiness
 181                     if pollfd.revents & libc::POLLHUP != 0 {
 182                         let e = self.take_error()?
 183                             .unwrap_or_else(|| {
 184                                 io::Error::new(io::ErrorKind::Other, "no error set after POLLHUP")
 185                             });
 186                         return Err(e);
 187                     }
 188
 189                     return Ok(());
 190                 }
 191             }
 192         }
 193     }
 194
 195     pub fn accept(&self, storage: *mut sockaddr, len: *mut socklen_t)
 196                   -> io::Result<Socket> {
 197         // Unfortunately the only known way right now to accept a socket and
 198         // atomically set the CLOEXEC flag is to use the `accept4` syscall on
 199         // Linux. This was added in 2.6.28, however, and because we support
 200         // 2.6.18 we must detect this support dynamically.
 201         if cfg!(target_os = "linux") {
 202             weak! {
 203                 fn accept4(c_int, *mut sockaddr, *mut socklen_t, c_int) -> c_int
 204             }
 205             if let Some(accept) = accept4.get() {
 206                 let res = cvt_r(|| unsafe {
 207                     accept(self.0.raw(), storage, len, SOCK_CLOEXEC)
 208                 });
 209                 match res {
 210                     Ok(fd) => return Ok(Socket(FileDesc::new(fd))),
 211                     Err(ref e) if e.raw_os_error() == Some(libc::ENOSYS) => {}
 212                     Err(e) => return Err(e),
 213                 }
 214             }
 215         }
 216
 217         let fd = cvt_r(|| unsafe {
 218             libc::accept(self.0.raw(), storage, len)
 219         })?;
 220         let fd = FileDesc::new(fd);
 221         fd.set_cloexec()?;
 222         Ok(Socket(fd))
 223     }
 224
 225     pub fn duplicate(&self) -> io::Result<Socket> {
 226         self.0.duplicate().map(Socket)
 227     }
 228
 229     fn recv_with_flags(&self, buf: &mut [u8], flags: c_int) -> io::Result<usize> {
 230         let ret = cvt(unsafe {
 231             libc::recv(self.0.raw(),
 232                        buf.as_mut_ptr() as *mut c_void,
 233                        buf.len(),
 234                        flags)
 235         })?;
 236         Ok(ret as usize)
 237     }
 238
 239     pub fn read(&self, buf: &mut [u8]) -> io::Result<usize> {
 240         self.recv_with_flags(buf, 0)
 241     }
 242
 243     pub fn peek(&self, buf: &mut [u8]) -> io::Result<usize> {
 244         self.recv_with_flags(buf, MSG_PEEK)
 245     }
 246
 247     fn recv_from_with_flags(&self, buf: &mut [u8], flags: c_int)
 248                             -> io::Result<(usize, SocketAddr)> {
 249         let mut storage: libc::sockaddr_storage = unsafe { mem::zeroed() };
 250         let mut addrlen = mem::size_of_val(&storage) as libc::socklen_t;
 251
 252         let n = cvt(unsafe {
 253             libc::recvfrom(self.0.raw(),
 254                         buf.as_mut_ptr() as *mut c_void,
 255                         buf.len(),
 256                         flags,
 257                         &mut storage as *mut _ as *mut _,
 258                         &mut addrlen)
 259         })?;
 260         Ok((n as usize, sockaddr_to_addr(&storage, addrlen as usize)?))
 261     }
 262
 263     pub fn recv_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
 264         self.recv_from_with_flags(buf, 0)
 265     }
 266
 267     pub fn peek_from(&self, buf: &mut [u8]) -> io::Result<(usize, SocketAddr)> {
 268         self.recv_from_with_flags(buf, MSG_PEEK)
 269     }
 270
 271     pub fn write(&self, buf: &[u8]) -> io::Result<usize> {
 272         self.0.write(buf)
 273     }
 274
 275     pub fn set_timeout(&self, dur: Option<Duration>, kind: libc::c_int) -> io::Result<()> {
 276         let timeout = match dur {
 277             Some(dur) => {
 278                 if dur.as_secs() == 0 && dur.subsec_nanos() == 0 {
 279                     return Err(io::Error::new(io::ErrorKind::InvalidInput,
 280                                               "cannot set a 0 duration timeout"));
 281                 }
 282
 283                 let secs = if dur.as_secs() > libc::time_t::max_value() as u64 {
 284                     libc::time_t::max_value()
 285                 } else {
 286                     dur.as_secs() as libc::time_t
 287                 };
 288                 let mut timeout = libc::timeval {
 289                     tv_sec: secs,
 290                     tv_usec: (dur.subsec_nanos() / 1000) as libc::suseconds_t,
 291                 };
 292                 if timeout.tv_sec == 0 && timeout.tv_usec == 0 {
 293                     timeout.tv_usec = 1;
 294                 }
 295                 timeout
 296             }
 297             None => {
 298                 libc::timeval {
 299                     tv_sec: 0,
 300                     tv_usec: 0,
 301                 }
 302             }
 303         };
 304         setsockopt(self, libc::SOL_SOCKET, kind, timeout)
 305     }
 306
 307     pub fn timeout(&self, kind: libc::c_int) -> io::Result<Option<Duration>> {
 308         let raw: libc::timeval = getsockopt(self, libc::SOL_SOCKET, kind)?;
 309         if raw.tv_sec == 0 && raw.tv_usec == 0 {
 310             Ok(None)
 311         } else {
 312             let sec = raw.tv_sec as u64;
 313             let nsec = (raw.tv_usec as u32) * 1000;
 314             Ok(Some(Duration::new(sec, nsec)))
 315         }
 316     }
 317
 318     pub fn shutdown(&self, how: Shutdown) -> io::Result<()> {
 319         let how = match how {
 320             Shutdown::Write => libc::SHUT_WR,
 321             Shutdown::Read => libc::SHUT_RD,
 322             Shutdown::Both => libc::SHUT_RDWR,
 323         };
 324         cvt(unsafe { libc::shutdown(self.0.raw(), how) })?;
 325         Ok(())
 326     }
 327
 328     pub fn set_nodelay(&self, nodelay: bool) -> io::Result<()> {
 329         setsockopt(self, libc::IPPROTO_TCP, libc::TCP_NODELAY, nodelay as c_int)
 330     }
 331
 332     pub fn nodelay(&self) -> io::Result<bool> {
 333         let raw: c_int = getsockopt(self, libc::IPPROTO_TCP, libc::TCP_NODELAY)?;
 334         Ok(raw != 0)
 335     }
 336
 337     pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
 338         let mut nonblocking = nonblocking as libc::c_int;
 339         cvt(unsafe { libc::ioctl(*self.as_inner(), libc::FIONBIO, &mut nonblocking) }).map(|_| ())
 340     }
 341
 342     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
 343         let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
 344         if raw == 0 {
 345             Ok(None)
 346         } else {
 347             Ok(Some(io::Error::from_raw_os_error(raw as i32)))
 348         }
 349     }
 350 }
 351
 352 impl AsInner<c_int> for Socket {
 353     fn as_inner(&self) -> &c_int { self.0.as_inner() }
 354 }
 355
 356 impl FromInner<c_int> for Socket {
 357     fn from_inner(fd: c_int) -> Socket { Socket(FileDesc::new(fd)) }
 358 }
 359
 360 impl IntoInner<c_int> for Socket {
 361     fn into_inner(self) -> c_int { self.0.into_raw() }
 362 }
 363
 364 // In versions of glibc prior to 2.26, there's a bug where the DNS resolver
 365 // will cache the contents of /etc/resolv.conf, so changes to that file on disk
 366 // can be ignored by a long-running program. That can break DNS lookups on e.g.
 367 // laptops where the network comes and goes. See
 368 // https://sourceware.org/bugzilla/show_bug.cgi?id=984. Note however that some
 369 // distros including Debian have patched glibc to fix this for a long time.
 370 //
 371 // A workaround for this bug is to call the res_init libc function, to clear
 372 // the cached configs. Unfortunately, while we believe glibc's implementation
 373 // of res_init is thread-safe, we know that other implementations are not
 374 // (https://github.com/rust-lang/rust/issues/43592). Code here in libstd could
 375 // try to synchronize its res_init calls with a Mutex, but that wouldn't
 376 // protect programs that call into libc in other ways. So instead of calling
 377 // res_init unconditionally, we call it only when we detect we're linking
 378 // against glibc version < 2.26. (That is, when we both know its needed and
 379 // believe it's thread-safe).
 380 pub fn res_init_if_glibc_before_2_26() -> io::Result<()> {
 381     // If the version fails to parse, we treat it the same as "not glibc".
 382     if let Some(Ok(version_str)) = glibc_version_cstr().map(CStr::to_str) {
 383         if let Some(version) = parse_glibc_version(version_str) {
 384             if version < (2, 26) {
 385                 let ret = unsafe { libc::res_init() };
 386                 if ret != 0 {
 387                     return Err(io::Error::last_os_error());
 388                 }
 389             }
 390         }
 391     }
 392     Ok(())
 393 }
 394
 395 fn glibc_version_cstr() -> Option<&'static CStr> {
 396     weak! {
 397         fn gnu_get_libc_version() -> *const libc::c_char
 398     }
 399     if let Some(f) = gnu_get_libc_version.get() {
 400         unsafe { Some(CStr::from_ptr(f())) }
 401     } else {
 402         None
 403     }
 404 }
 405
 406 // Returns Some((major, minor)) if the string is a valid "x.y" version,
 407 // ignoring any extra dot-separated parts. Otherwise return None.
 408 fn parse_glibc_version(version: &str) -> Option<(usize, usize)> {
 409     let mut parsed_ints = version.split(".").map(str::parse::<usize>).fuse();
 410     match (parsed_ints.next(), parsed_ints.next()) {
 411         (Some(Ok(major)), Some(Ok(minor))) => Some((major, minor)),
 412         _ => None
 413     }
 414 }
 415
 416 #[cfg(test)]
 417 mod test {
 418     use super::*;
 419
 420     #[test]
 421     fn test_res_init() {
 422         // This mostly just tests that the weak linkage doesn't panic wildly...
 423         res_init_if_glibc_before_2_26().unwrap();
 424     }
 425
 426     #[test]
 427     fn test_parse_glibc_version() {
 428         let cases = [
 429             ("0.0", Some((0, 0))),
 430             ("01.+2", Some((1, 2))),
 431             ("3.4.5.six", Some((3, 4))),
 432             ("1", None),
 433             ("1.-2", None),
 434             ("1.foo", None),
 435             ("foo.1", None),
 436         ];
 437         for &(version_str, parsed) in cases.iter() {
 438             assert_eq!(parsed, parse_glibc_version(version_str));
 439         }
 440     }
 441 }