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Fix WASIX socket connect to detect connection failures #6059

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Fix WASIX socket connect to detect connection failures #6059

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276708c
Initial plan
Copilot Jan 15, 2026
c8eaeb5
Fix socket connect to properly detect connection failures
Copilot Jan 15, 2026
b05aec3
Address code review feedback for socket error handling
Copilot Jan 15, 2026
a67763f
Merge branch 'main' into copilot/fix-wasix-socket-connection
marxin Mar 27, 2026
b6e2f29
fix cargo fmt
marxin Mar 27, 2026
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32 changes: 31 additions & 1 deletion lib/virtual-net/src/host.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -718,7 +718,37 @@ impl VirtualIoSource for LocalTcpStream {
}

#[cfg(not(target_os = "windows"))]
match libc_poll(stream.as_raw_fd(), libc::POLLOUT | libc::POLLHUP) {
match libc_poll(
stream.as_raw_fd(),
libc::POLLOUT | libc::POLLHUP | libc::POLLERR,
) {
Some(val) if (val & libc::POLLERR) != 0 => {
Comment on lines +721 to +725
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Copilot AI Mar 27, 2026

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This change fixes a subtle readiness/connection-error behavior; please add a regression test to cover it. A stable approach is to create a nonblocking TCP socket to a known-closed localhost port (e.g., bind a TcpListener to 127.0.0.1:0, capture the port, drop the listener, then attempt connect), wrap it as LocalTcpStream, and assert poll_write_ready resolves to Err(NetworkError::ConnectionRefused) (or appropriate mapped error) instead of reporting writable.

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// Get the actual socket error using SO_ERROR
let mut error: libc::c_int = 0;
let mut len = std::mem::size_of::<libc::c_int>() as libc::socklen_t;
let result = unsafe {
libc::getsockopt(
stream.as_raw_fd(),
libc::SOL_SOCKET,
libc::SO_ERROR,
&mut error as *mut libc::c_int as *mut libc::c_void,
&mut len,
)
};
if result != 0 {
// getsockopt itself failed
let io_error = std::io::Error::last_os_error();
return Poll::Ready(Err(io_err_into_net_error(io_error)));
}
if error != 0 {
// Socket has a pending error
let io_error = std::io::Error::from_raw_os_error(error);
return Poll::Ready(Err(io_err_into_net_error(io_error)));
}
// POLLERR was set but SO_ERROR is 0 - this shouldn't normally happen,
// but we'll treat it as a generic IO error
return Poll::Ready(Err(NetworkError::IOError));
}
Some(val) if (val & libc::POLLHUP) != 0 => {
return Poll::Ready(Ok(0));
}
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