Panic on socket connect on MacOS Mojave

[n8henrie]

MacOS 10.14.2
rustc 1.31.1 (b6c32da9b 2018-12-18)

Panics at socket.connect("239.255.255.250:1900").unwrap(); in src/dlna/discovery.rs.

$ RUST_BACKTRACE=1 target/debug/rustymedia -l stuff=~/Movies | pbcopy
Listening on http://[fe80::c2c:d1e:7cd:7918]:4950/
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Os { code: 22, kind: InvalidInput, message: "Invalid argument" }', libcore/result.rs:1009:5
stack backtrace:
   0: std::sys::unix::backtrace::tracing::imp::unwind_backtrace
             at libstd/sys/unix/backtrace/tracing/gcc_s.rs:49
   1: std::sys_common::backtrace::print
             at libstd/sys_common/backtrace.rs:71
             at libstd/sys_common/backtrace.rs:59
   2: std::panicking::default_hook::{{closure}}
             at libstd/panicking.rs:211
   3: std::panicking::default_hook
             at libstd/panicking.rs:227
   4: <std::panicking::begin_panic::PanicPayload<A> as core::panic::BoxMeUp>::get
             at libstd/panicking.rs:476
   5: std::panicking::continue_panic_fmt
             at libstd/panicking.rs:390
   6: std::panicking::try::do_call
             at libstd/panicking.rs:325
   7: core::ptr::drop_in_place
             at libcore/panicking.rs:77
   8: core::alloc::Layout::repeat
             at libcore/macros.rs:26
   9: futures::task_impl::NotifyHandle::new
             at libcore/result.rs:808
  10: <hyper::proto::request::Request>::body
             at src/dlna/discovery.rs:13
  11: rustymedia::result_main
             at src/bin/rustymedia.rs:94
  12: rustymedia::main
             at src/bin/rustymedia.rs:103
  13: std::rt::lang_start::{{closure}}
             at libstd/rt.rs:74
  14: std::panicking::try::do_call
             at libstd/rt.rs:59
             at libstd/panicking.rs:310
  15: panic_unwind::imp::find_eh_action::{{closure}}
             at libpanic_unwind/lib.rs:102
  16: std::alloc::default_alloc_error_hook
             at libstd/panicking.rs:289
             at libstd/panic.rs:392
             at libstd/rt.rs:58
  17: std::rt::lang_start
             at libstd/rt.rs:74
  18: rustymedia::main

[kevincox]

To be honest don't have any clue what the problem is here. It guess we would have to find out how to do this broadcast on macos.

[n8henrie]

Just some notes while I look into it (mostly for my reference, you likely know all this).

I have a Python app that makes a similar UPnP broadcast. It binds '':1900, where '' is INADDR_ANY for IPV4 addresses.

:: is the IPv6 unspecified address, as defined here.

Could it be because :: is an IPv6 address, and 239.255.255.250 is an IPv4 broadcast address? I don't know why this would run on Linux but not MacOS, but it builds and runs (on both MacOS and Linux) if I change the line to: let socket = std::net::UdpSocket::bind("0.0.0.0:0").unwrap();.

EDIT:
Not sure if this is relevant, but if I debug print the socket before and after connect in Arch Linux:

Listening on http://192.168.0.65:4950/
UdpSocket { addr: V6([::]:45885), fd: 9 }
UdpSocket { addr: V6([::ffff:192.168.0.65]:45885), fd: 9 }

Note the IPv4 address at the last line.