Add getter for local_addr on TcpSocket (#1379)

src/net/tcp/socket.rs

@@ -105,6 +105,13 @@ impl TcpSocket {
     pub fn set_linger(&self, dur: Option<Duration>) -> io::Result<()> {
         sys::tcp::set_linger(self.sys, dur)
     }
+
+    /// Returns the local address of this socket
+    ///
+    /// Will return `Err` result in windows if called before calling `bind`
+    pub fn get_localaddr(&self) -> io::Result<SocketAddr> {
+        sys::tcp::get_localaddr(self.sys)
+    }
 }
 
 impl Drop for TcpSocket {

src/sys/shell/tcp.rs

@@ -53,3 +53,7 @@ pub(crate) fn set_linger(_: TcpSocket, _: Option<Duration>) -> io::Result<()> {
 pub fn accept(_: &net::TcpListener) -> io::Result<(net::TcpStream, SocketAddr)> {
     os_required!();
 }
+
+pub(crate) fn get_localaddr(_: TcpSocket) -> io::Result<SocketAddr> {
+    os_required!();
+}

src/sys/unix/tcp.rs

@@ -103,6 +103,19 @@ pub(crate) fn get_reuseport(socket: TcpSocket) -> io::Result<bool> {
     Ok(optval != 0)
 }
 
+pub(crate) fn get_localaddr(socket: TcpSocket) -> io::Result<SocketAddr> {
+    let mut addr: libc::sockaddr_storage = unsafe { std::mem::zeroed() };
+    let mut length = size_of::<libc::sockaddr_storage>() as libc::socklen_t;
+
+    syscall!(getsockname(
+        socket,
+        &mut addr as *mut _ as *mut _,
+        &mut length
+    ))?;
+
+    unsafe { to_socket_addr(&addr) }
+}
+
 pub(crate) fn set_linger(socket: TcpSocket, dur: Option<Duration>) -> io::Result<()> {
     let val: libc::linger = libc::linger {
         l_onoff: if dur.is_some() { 1 } else { 0 },

src/sys/windows/tcp.rs

@@ -1,14 +1,17 @@
 use std::io;
 use std::mem::size_of;
-use std::net::{self, SocketAddr};
+use std::net::{self, SocketAddr, SocketAddrV4, SocketAddrV6};
 use std::time::Duration;
 use std::os::windows::io::FromRawSocket;
 use std::os::windows::raw::SOCKET as StdSocket; // winapi uses usize, stdlib uses u32/u64.
 
 use winapi::ctypes::{c_char, c_int, c_ushort};
+use winapi::shared::ws2def::{SOCKADDR_STORAGE, AF_INET, SOCKADDR_IN};
+use winapi::shared::ws2ipdef::SOCKADDR_IN6_LH;
+
 use winapi::shared::minwindef::{BOOL, TRUE, FALSE};
 use winapi::um::winsock2::{
-    self, closesocket, linger, setsockopt, getsockopt, PF_INET, PF_INET6, SOCKET, SOCKET_ERROR,
+    self, closesocket, linger, setsockopt, getsockopt, getsockname, PF_INET, PF_INET6, SOCKET, SOCKET_ERROR,
     SOCK_STREAM, SOL_SOCKET, SO_LINGER, SO_REUSEADDR,
 };
 
@@ -103,6 +106,31 @@ pub(crate) fn get_reuseaddr(socket: TcpSocket) -> io::Result<bool> {
     }
 }
 
+pub(crate) fn get_localaddr(socket: TcpSocket) -> io::Result<SocketAddr> {
+    let mut addr: SOCKADDR_STORAGE = unsafe { std::mem::zeroed() };
+    let mut length = std::mem::size_of_val(&addr) as c_int;
+
+    match unsafe { getsockname(
+        socket,
+        &mut addr as *mut _ as *mut _,
+        &mut length
+    ) } {
+        SOCKET_ERROR => Err(io::Error::last_os_error()),
+        _ => {
+            let storage: *const SOCKADDR_STORAGE = (&addr) as *const _;
+            if addr.ss_family as c_int == AF_INET {
+                let sock_addr : SocketAddrV4 = unsafe { *(storage as *const SOCKADDR_IN as *const _) };
+                Ok(sock_addr.into())
+            } else {
+                let sock_addr : SocketAddrV6 = unsafe { *(storage as *const SOCKADDR_IN6_LH as *const _) };
+                Ok(sock_addr.into())
+            }
+        },
+    }
+
+
+}
+
 pub(crate) fn set_linger(socket: TcpSocket, dur: Option<Duration>) -> io::Result<()> {
     let val: linger = linger {
         l_onoff: if dur.is_some() { 1 } else { 0 },

tests/tcp_socket.rs

@@ -37,3 +37,22 @@ fn set_reuseport() {
 
     let _ = socket.listen(128).unwrap();
 }
+
+#[test]
+fn get_localaddr() {
+    let expected_addr = "127.0.0.1:0".parse().unwrap();
+    let socket = TcpSocket::new_v4().unwrap();
+
+    //Windows doesn't support calling getsockname before calling `bind`
+    #[cfg(not(windows))]
+    assert_eq!("0.0.0.0:0", socket.get_localaddr().unwrap().to_string());
+
+    socket.bind(expected_addr).unwrap();
+
+    let actual_addr = socket.get_localaddr().unwrap();
+
+    assert_eq!(expected_addr.ip(), actual_addr.ip());
+    assert!(actual_addr.port() > 0);
+
+    let _ = socket.listen(128).unwrap();
+}