OS Error 10014 (Bad address) when using "localhost" in UDP source address on Win7

[joep27182]

Consider this code:

use std::net::UdpSocket;

fn main() {
    let local_addr = "localhost:8900";
    let target_addr = "example.com:8900";

    let socket = UdpSocket::bind(local_addr).unwrap();
    let buf : [u8; 9] = [176,18,0,9,161,0,0,1,1];
    socket.send_to(&buf[..],target_addr).unwrap();
}

which fails like this:

thread '<main>' panicked at 'calledResult::unwrap()on anErrvalue: Error { repr: Os { code: 10014, message: "Bei dem Versuch das Zeigerargument eines Aufrufs zu\r\nverwenden, wurde eine ung\u{fc}ltige Zeigeradresse gefunden." } }', ../src/libcore\result.rs:746

The error occurs on the last line by the way.

If you write let local_addr="127.0.0.1:8900";, it works just fine (no panic).

If i remember correctly, this worked on Linux, so it should be an os specific issue. Of course you can just use an ip for the source address, but this kind of error shouldn't occur nevertheless right?

Meta

OS: Windows 7 Professional 64bit

rustc --version --verbose:
rustc 1.9.0 (e4e8b66 2016-05-18)
binary: rustc
commit-hash: e4e8b66
commit-date: 2016-05-18
host: x86_64-pc-windows-msvc
release: 1.9.0

Backtrace:

stack backtrace:
   0:        0x13f82138b - std::rt::lang_start::h5b0863080165c75e
   1:        0x13f82078b - std::rt::lang_start::h5b0863080165c75e
   2:        0x13f81449f - std::sys_common::unwind::begin_unwind_inner::h39d40f52add53ef7
   3:        0x13f814f8d - std::sys_common::unwind::begin_unwind_fmt::h64c0ff793199cc1b
   4:        0x13f81c4ab - rust_begin_unwind
   5:        0x13f824365 - core::panicking::panic_fmt::h73bf9d7e8e891a73
   6:        0x13f8115e3 - unwrap_failed<std::io::error::Error>
                        at [redacted]\src\libcore\macros.rs:29
   7:        0x13f812c34 - unwrap
                        at [redacted]\src\libcore\result.rs:687
   8:        0x13f811197 - main
                        at [redacted]\src\bin\test_udp_problem.rs:12
   9:        0x13f820158 - std::rt::lang_start::h5b0863080165c75e
  10:        0x13f81c418 - std::sys_common::thread_local::StaticKey::lazy_init::h0dbf04c687960888
  11:        0x13f81ff07 - std::rt::lang_start::h5b0863080165c75e
  12:        0x13f813179 - main
  13:        0x13f827c7a - __tmainCRTStartup
                        at f:\dd\vctools\crt\crtw32\dllstuff\crtexe.c:626
  14:         0x76cb59bc - BaseThreadInitThunk

[kennytm]

Repo on Windows 10. Seems to crash on OS X as well.

The localhost is resolved to the IPv6 address [::1] and then the IPv4 address 127.0.0.1, and UdpSocket will only bind to the first address if successful. So the UDP socket is bound to an IPv6 address, and can only send data to IPv6 hosts.

Meanwhile, example.com is first resolved to the IPv4 address 93.184.216.34 and then the IPv6 one [2606:2800:220:1:248:1893:25c8:1946] (if the OS supports that). The implementation of send_to just send the data to the first address, regardless of if the result is Ok or Err.

The 10014 is due to sending data from IPv6 socket to IPv4 host.

So there are two problems shown from this issue:

1. maybe send_to should use each_addr, or at least filter the address family?
2. need to have some way to prioritize IPv4 address for localhost when using ToSocketAddrs. (IPv6 support is not good on internet, even if send_to picked [2606:...] it could still fail with 10049)

[alexcrichton]

@kennytm's diagnosis sounds like it'd do it. We can probably figure out the local address type by calling local_addr and inspecting it, and then we should probably just filter the addresses returned to only those of the same kind.