win: allow bound/connected socket in uv_tcp_open()

On Unix you can pass bound and even connected socket to uv_tcp_open
and it will work as expected: you can run uv_listen or other io
functions (uv_read, uv_write) on it without problems.
On windows on the other hand the function always assumes to have clean
socket and for example uv_listen will try to bind it again, and
uv_read/write will return with errors about unreadable streams
(basically invalid internal flags).

To check if socket is already bound uv_tcp_getsockname is called which
on windows returns error when socket is unbound. To further
differentiate connected one from just bound, uv_tcp_getpeername also
returns error but when target socket is not connected.

PR-URL: https://github.com/libuv/libuv/pull/1447
Reviewed-By: Bartosz Sosnowski <bartosz@janeasystems.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

src/win/tcp.c

@@ -1446,6 +1446,8 @@ int uv_tcp_open(uv_tcp_t* handle, uv_os_sock_t sock) {
   WSAPROTOCOL_INFOW protocol_info;
   int opt_len;
   int err;
+  struct sockaddr_storage saddr;
+  int saddr_len;
 
   /* Detect the address family of the socket. */
   opt_len = (int) sizeof protocol_info;
@@ -1466,6 +1468,19 @@ int uv_tcp_open(uv_tcp_t* handle, uv_os_sock_t sock) {
     return uv_translate_sys_error(err);
   }
 
+  /* Support already active socket. */
+  saddr_len = sizeof(saddr);
+  if (!uv_tcp_getsockname(handle, (struct sockaddr*) &saddr, &saddr_len)) {
+    /* Socket is already bound. */
+    handle->flags |= UV_HANDLE_BOUND;
+    saddr_len = sizeof(saddr);
+    if (!uv_tcp_getpeername(handle, (struct sockaddr*) &saddr, &saddr_len)) {
+      /* Socket is already connected. */
+      uv_connection_init((uv_stream_t*) handle);
+      handle->flags |= UV_HANDLE_READABLE | UV_HANDLE_WRITABLE;
+    }
+  }
+
   return 0;
 }
 

test/test-list.h

@@ -81,6 +81,8 @@ TEST_DECLARE   (tcp_try_write)
 TEST_DECLARE   (tcp_write_queue_order)
 TEST_DECLARE   (tcp_open)
 TEST_DECLARE   (tcp_open_twice)
+TEST_DECLARE   (tcp_open_bound)
+TEST_DECLARE   (tcp_open_connected)
 TEST_DECLARE   (tcp_connect_error_after_write)
 TEST_DECLARE   (tcp_shutdown_after_write)
 TEST_DECLARE   (tcp_bind_error_addrinuse)
@@ -491,6 +493,9 @@ TASK_LIST_START
   TEST_ENTRY  (tcp_open)
   TEST_HELPER (tcp_open, tcp4_echo_server)
   TEST_ENTRY  (tcp_open_twice)
+  TEST_ENTRY  (tcp_open_bound)
+  TEST_ENTRY  (tcp_open_connected)
+  TEST_HELPER (tcp_open_connected, tcp4_echo_server)
 
   TEST_ENTRY  (tcp_shutdown_after_write)
   TEST_HELPER (tcp_shutdown_after_write, tcp4_echo_server)

test/test-tcp-open.c

@@ -218,3 +218,60 @@ TEST_IMPL(tcp_open_twice) {
   MAKE_VALGRIND_HAPPY();
   return 0;
 }
+
+
+TEST_IMPL(tcp_open_bound) {
+  struct sockaddr_in addr;
+  uv_tcp_t server;
+  uv_os_sock_t sock;
+
+  startup();
+  sock = create_tcp_socket();
+
+  ASSERT(0 == uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  ASSERT(0 == uv_tcp_init(uv_default_loop(), &server));
+
+  ASSERT(0 == bind(sock, (struct sockaddr*) &addr, sizeof(addr)));
+
+  ASSERT(0 == uv_tcp_open(&server, sock));
+
+  ASSERT(0 == uv_listen((uv_stream_t*) &server, 128, NULL));
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}
+
+
+TEST_IMPL(tcp_open_connected) {
+  struct sockaddr_in addr;
+  uv_tcp_t client;
+  uv_os_sock_t sock;
+  uv_buf_t buf = uv_buf_init("PING", 4);
+
+  ASSERT(0 == uv_ip4_addr("127.0.0.1", TEST_PORT, &addr));
+
+  startup();
+  sock = create_tcp_socket();
+
+  ASSERT(0 == connect(sock, (struct sockaddr*) &addr,  sizeof(addr)));
+
+  ASSERT(0 == uv_tcp_init(uv_default_loop(), &client));
+
+  ASSERT(0 == uv_tcp_open(&client, sock));
+
+  ASSERT(0 == uv_write(&write_req, (uv_stream_t*) &client, &buf, 1, write_cb));
+
+  ASSERT(0 == uv_shutdown(&shutdown_req, (uv_stream_t*) &client, shutdown_cb));
+
+  ASSERT(0 == uv_read_start((uv_stream_t*) &client, alloc_cb, read_cb));
+
+  uv_run(uv_default_loop(), UV_RUN_DEFAULT);
+
+  ASSERT(shutdown_cb_called == 1);
+  ASSERT(write_cb_called == 1);
+  ASSERT(close_cb_called == 1);
+
+  MAKE_VALGRIND_HAPPY();
+  return 0;
+}