TcpStream::connect_timeout with Duration::MAX never succeeds on Windows

[hartwork]

Hello! 👋

I tried this code on Windows:

use std::net::{TcpStream, ToSocketAddrs};
use std::time::Duration;

fn main() {
    let address_result = "google.com:80".to_socket_addrs();
    let address = address_result.unwrap().next().unwrap();
    TcpStream::connect_timeout(&address, Duration::MAX).expect("Google is offline?!");
    println!("Never gets here on Windows (https://github.com/rust-lang/rust/issues/112405).");
}

I expected to see this happen: Success for an available address like google.com:80 and blocking forever (or until TCP timeout) for hostname.invalid:80 just like on Linux.

Instead, this happened: the call never succeeds, not even for google.com:80 on Windows.

Related: hartwork/rust-for-it@5056e69

Meta

rustc --version --verbose:

# rustc --version --verbose
rustc 1.69.0 (84c898d65 2023-04-16)
binary: rustc
commit-hash: 84c898d65adf2f39a5a98507f1fe0ce10a2b8dbc
commit-date: 2023-04-16
host: x86_64-pc-windows-msvc
release: 1.69.0
LLVM version: 15.0.7

[ChrisDenton]

Thanks for the report! My best guess from quickly glancing at the code is that the problem is here:

rust/library/std/src/sys/windows/net.rs

Lines 161 to 164 in 50f2176

	let mut timeout = c::timeval {
	tv_sec: timeout.as_secs() as c_long,
	tv_usec: (timeout.subsec_nanos() / 1000) as c_long,
	};

This is using as to convert u64 seconds into an i32 (aka c_long). Which means that it can become a negative timeout. If I'm right then the fix here would be to limit the timeout to i32::MAX or less.

[eval-exec]

@rustbot claim

[hartwork]

@ChrisDenton @eval-exec thanks for your work on this and pushing it over the finish line! 👍 🙏