Auto merge of #1182 - xmclark:add-socket-functions-for-windows, r=alexcrichton

add some socket functions and a SOCKET type for windows

This PR adds a few of the socket functions for windows. Some targets use the `stdcall` calling convention for these functions, so I put them in an `extern "system"` block ([see the nomicon](https://doc.rust-lang.org/nomicon/ffi.html#foreign-calling-conventions)).

Author: bors

src/windows/mod.rs

@@ -50,6 +50,8 @@ pub type ino_t = u16;
 pub enum timezone {}
 pub type time64_t = i64;
 
+pub type SOCKET = ::uintptr_t;
+
 s! {
     // note this is the struct called stat64 in Windows. Not stat, nor stati64.
     pub struct stat {
@@ -93,6 +95,11 @@ s! {
         pub tv_sec: time_t,
         pub tv_nsec: c_long,
     }
+
+    pub struct sockaddr {
+        pub sa_family: c_ushort,
+        pub sa_data: [c_char; 14],
+    }
 }
 
 pub const INT_MIN: c_int = -2147483648;
@@ -383,6 +390,34 @@ extern {
                       locale: *const wchar_t) -> *mut wchar_t;
 }
 
+extern "system" {
+    pub fn listen(s: SOCKET, backlog: ::c_int) -> ::c_int;
+    pub fn accept(s: SOCKET, addr: *mut ::sockaddr,
+                  addrlen: *mut ::c_int) -> SOCKET;
+    pub fn bind(s: SOCKET, name: *const ::sockaddr,
+                namelen: ::c_int) -> ::c_int;
+    pub fn connect(s: SOCKET, name: *const ::sockaddr,
+                   namelen: ::c_int) -> ::c_int;
+    pub fn getpeername(s: SOCKET, name: *mut ::sockaddr,
+                       nameln: *mut ::c_int) -> ::c_int;
+    pub fn getsockname(s: SOCKET, name: *mut ::sockaddr,
+                       nameln: *mut ::c_int) -> ::c_int;
+    pub fn getsockopt(s: SOCKET, level: ::c_int, optname: ::c_int,
+                      optval: *mut ::c_char,
+                      optlen: *mut ::c_int) -> ::c_int;
+    pub fn recvfrom(s: SOCKET, buf: *mut  ::c_char, len: ::c_int,
+                    flags: ::c_int, from: *mut ::sockaddr,
+                    fromlen: *mut ::c_int) -> ::c_int;
+    pub fn sendto(s: SOCKET, buf: *const  ::c_char, len: ::c_int,
+                  flags: ::c_int, to: *const ::sockaddr,
+                  tolen: ::c_int) -> ::c_int;
+    pub fn setsockopt(s: SOCKET, level: ::c_int, optname: ::c_int,
+                      optval: *const  ::c_char,
+                      optlen: ::c_int) -> ::c_int;
+    pub fn socket(af: ::c_int, socket_type: ::c_int,
+                  protocol: ::c_int) -> SOCKET;
+}
+
 cfg_if! {
     if #[cfg(core_cvoid)] {
         pub use core::ffi::c_void;