Provide bind_device_by_index_v{4|6} methods for linux.

[Frostie314159]

Hi, it would be nice if we had the functionality for binding a socket to an interface under linux, since that functionality is available.

[Thomasdezeeuw]

A pr to add this would be welcome.

[Frostie314159]

Sure, I'll get to this next week.

[carlocorradini]

Any update?
This is super useful ☺️🥳

[Thomasdezeeuw]

Any update? This is super useful ☺️🥳

No pr was made, but they're still welcome.

[Frostie314159]

I'm in the progress of writing one, however I'm not entirely sure how to go about it.

[Thomasdezeeuw]

I just look at the code and we have Socket::bind_device_by_index_v4:

socket2/src/sys/unix.rs

Lines 2006 to 2045 in c93cdcc

	pub fn bind_device_by_index_v4(&self, interface: Option<NonZeroU32>) -> io::Result<()> {
	let index = interface.map_or(0, NonZeroU32::get);
	unsafe { setsockopt(self.as_raw(), IPPROTO_IP, libc::IP_BOUND_IF, index) }
	}
	/// Sets the value for `IPV6_BOUND_IF` option on this socket.
	///
	/// If a socket is bound to an interface, only packets received from that
	/// particular interface are processed by the socket.
	///
	/// If `interface` is `None`, the binding is removed. If the `interface`
	/// index is not valid, an error is returned.
	///
	/// One can use [`libc::if_nametoindex`] to convert an interface alias to an
	/// index.
	#[cfg(all(
	feature = "all",
	any(
	target_os = "ios",
	target_os = "macos",
	target_os = "tvos",
	target_os = "watchos",
	)
	))]
	#[cfg_attr(
	docsrs,
	doc(cfg(all(
	feature = "all",
	any(
	target_os = "ios",
	target_os = "macos",
	target_os = "tvos",
	target_os = "watchos",
	)
	)))
	)]
	pub fn bind_device_by_index_v6(&self, interface: Option<NonZeroU32>) -> io::Result<()> {
	let index = interface.map_or(0, NonZeroU32::get);
	unsafe { setsockopt(self.as_raw(), IPPROTO_IPV6, libc::IPV6_BOUND_IF, index) }
	}

. Or is this about another setting then IP_BOUND_IF?

[Frostie314159]

That setting is Apple specific, this is about the Linux socket option.