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Make TCP connect() handle EINTR correctly
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According to the POSIX standard, if connect() is interrupted by a
signal that is caught while blocked waiting to establish a connection,
connect() shall fail and set errno to EINTR, but the connection
request shall not be aborted, and the connection shall be established
asynchronously.

If asynchronous connection was successfully established after EINTR
and before the next connection attempt, OS returns EISCONN that was
handled as an error before. This behavior is fixed now and we handle
it as success.

The problem affects MacOS users: Linux doesn't return EISCONN in this
case, Windows connect() can not be interrupted without an old-fashoin
WSACancelBlockingCall function that is not used in the library.
So current solution gives connect() as OS specific implementation.
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darthunix committed Oct 13, 2023
1 parent 130ff8c commit a3d422a
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Showing 5 changed files with 37 additions and 12 deletions.
6 changes: 6 additions & 0 deletions library/std/src/sys/hermit/net.rs
Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,12 @@ impl Socket {
unimplemented!()
}

pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
let (addr, len) = addr.into_inner();
cvt_r(|| unsafe { netc::connect(self.as_raw_fd(), addr.as_ptr(), len) })?;
Ok(())
}

pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
self.set_nonblocking(true)?;
let r = unsafe {
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10 changes: 6 additions & 4 deletions library/std/src/sys/solid/net.rs
Original file line number Diff line number Diff line change
Expand Up @@ -233,12 +233,14 @@ impl Socket {
}
}

pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
let (addr, len) = addr.into_inner();
cvt(unsafe { netc::connect(self.0.raw(), addr.as_ptr(), len) })
}

pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
self.set_nonblocking(true)?;
let r = unsafe {
let (addr, len) = addr.into_inner();
cvt(netc::connect(self.0.raw(), addr.as_ptr(), len))
};
let r = self.connect(addr);
self.set_nonblocking(false)?;

match r {
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17 changes: 17 additions & 0 deletions library/std/src/sys/unix/net.rs
Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@ use crate::net::{Shutdown, SocketAddr};
use crate::os::unix::io::{AsFd, AsRawFd, BorrowedFd, FromRawFd, IntoRawFd, RawFd};
use crate::str;
use crate::sys::fd::FileDesc;
use crate::sys::unix::IsMinusOne;
use crate::sys_common::net::{getsockopt, setsockopt, sockaddr_to_addr};
use crate::sys_common::{AsInner, FromInner, IntoInner};
use crate::time::{Duration, Instant};
Expand Down Expand Up @@ -140,6 +141,22 @@ impl Socket {
unimplemented!()
}

pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
let (addr, len) = addr.into_inner();
loop {
let result = unsafe { libc::connect(self.as_raw_fd(), addr.as_ptr(), len) };
if result.is_minus_one() {
let err = crate::sys::os::errno();
match err {
libc::EINTR => continue,
libc::EISCONN => return Ok(()),
_ => return Err(io::Error::from_raw_os_error(err)),
}
}
return Ok(());
}
}

pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
self.set_nonblocking(true)?;
let r = unsafe {
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12 changes: 7 additions & 5 deletions library/std/src/sys/windows/net.rs
Original file line number Diff line number Diff line change
Expand Up @@ -140,13 +140,15 @@ impl Socket {
}
}

pub fn connect(&self, addr: &SocketAddr) -> io::Result<()> {
let (addr, len) = addr.into_inner();
let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
cvt(result).map(drop)
}

pub fn connect_timeout(&self, addr: &SocketAddr, timeout: Duration) -> io::Result<()> {
self.set_nonblocking(true)?;
let result = {
let (addr, len) = addr.into_inner();
let result = unsafe { c::connect(self.as_raw(), addr.as_ptr(), len) };
cvt(result).map(drop)
};
let result = self.connect(addr);
self.set_nonblocking(false)?;

match result {
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4 changes: 1 addition & 3 deletions library/std/src/sys_common/net.rs
Original file line number Diff line number Diff line change
Expand Up @@ -226,9 +226,7 @@ impl TcpStream {
init();

let sock = Socket::new(addr, c::SOCK_STREAM)?;

let (addr, len) = addr.into_inner();
cvt_r(|| unsafe { c::connect(sock.as_raw(), addr.as_ptr(), len) })?;
sock.connect(addr)?;
Ok(TcpStream { inner: sock })
}

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