Merge #835

835: Add socket options for IP_TRANSPARENT / BIND_ANY r=asomers a=justinlatimer

Add socket options for implementing a transparent proxy.
Sources:
[Linux](https://www.kernel.org/doc/Documentation/networking/tproxy.txt)
[OpenBSD](https://man.openbsd.org/setsockopt.2#SO_BINDANY)
[FreeBSD](https://www.freebsd.org/cgi/man.cgi?query=ip&manpath=FreeBSD+11.1-RELEASE)

Thanks!

CHANGELOG.md

@@ -54,6 +54,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#826](https://github.com/nix-rust/nix/pull/826))
 - Added `nix::sys::socket::LinkAddr` on Linux and all bsdlike system.
   ([#813](https://github.com/nix-rust/nix/pull/813))
+- Add socket options for `IP_TRANSPARENT` / `BIND_ANY`.
+  ([#835](https://github.com/nix-rust/nix/pull/835))
 
 ### Changed
 - Exposed the `mqueue` module for all supported operating systems.

src/sys/socket/sockopt.rs

@@ -179,6 +179,12 @@ sockopt_impl!(GetOnly, AcceptConn, libc::SOL_SOCKET, libc::SO_ACCEPTCONN, bool);
 #[cfg(any(target_os = "linux", target_os = "android"))]
 sockopt_impl!(GetOnly, OriginalDst, libc::SOL_IP, libc::SO_ORIGINAL_DST, libc::sockaddr_in);
 sockopt_impl!(Both, ReceiveTimestamp, libc::SOL_SOCKET, libc::SO_TIMESTAMP, bool);
+#[cfg(any(target_os = "linux", target_os = "android"))]
+sockopt_impl!(Both, IpTransparent, libc::SOL_IP, libc::IP_TRANSPARENT, bool);
+#[cfg(target_os = "openbsd")]
+sockopt_impl!(Both, BindAny, libc::SOL_SOCKET, libc::SO_BINDANY, bool);
+#[cfg(target_os = "freebsd")]
+sockopt_impl!(Both, BindAny, libc::IPPROTO_IP, libc::IP_BINDANY, bool);
 
 /*
  *