Allow server sockets to rebind to same port if there is nothing actively listening on that port.

net/socket/tcp_server_socket_win.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/socket/tcp_server_socket_win.h"
 
 #include <mstcpip.h>
 
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_util.h"
 #include "net/base/winsock_init.h"
 #include "net/base/winsock_util.h"
 #include "net/socket/socket_net_log_params.h"
 #include "net/socket/tcp_client_socket.h"
 
 namespace net {
 
 TCPServerSocketWin::TCPServerSocketWin(net::NetLog* net_log,
                                        const net::NetLog::Source& source)
     : socket_(INVALID_SOCKET),
       socket_event_(WSA_INVALID_EVENT),
       accept_socket_(NULL),
+      reuse_address_(false),
       net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_SOCKET)) {
   net_log_.BeginEvent(NetLog::TYPE_SOCKET_ALIVE,
                       source.ToEventParametersCallback());
   EnsureWinsockInit();
 }
 
 TCPServerSocketWin::~TCPServerSocketWin() {
   Close();
   net_log_.EndEvent(NetLog::TYPE_SOCKET_ALIVE);
 }
 
+void TCPServerSocketWin::AllowAddressReuse() {
+  DCHECK(CalledOnValidThread());
+  DCHECK_EQ(socket_, INVALID_SOCKET);
+  DCHECK_EQ(socket_event_, WSA_INVALID_EVENT);
+
+  reuse_address_ = true;
+}
+
 int TCPServerSocketWin::Listen(const IPEndPoint& address, int backlog) {
   DCHECK(CalledOnValidThread());
   DCHECK_GT(backlog, 0);
   DCHECK_EQ(socket_, INVALID_SOCKET);
   DCHECK_EQ(socket_event_, WSA_INVALID_EVENT);
 
   socket_event_ = WSACreateEvent();
   if (socket_event_ == WSA_INVALID_EVENT) {
     PLOG(ERROR) << "WSACreateEvent()";
     return ERR_FAILED;
   }
 
   socket_ = socket(address.GetFamily(), SOCK_STREAM, IPPROTO_TCP);
   if (socket_ < 0) {
     PLOG(ERROR) << "socket() returned an error";
     return MapSystemError(WSAGetLastError());
   }
 
   if (SetNonBlocking(socket_)) {
     int result = MapSystemError(WSAGetLastError());
     Close();
     return result;
   }
 
+  int result = SetSocketOptions();
+  if (result != OK)
+    return result;
+
   SockaddrStorage storage;
   if (!address.ToSockAddr(storage.addr, &storage.addr_len))
     return ERR_INVALID_ARGUMENT;
 
-  int result = bind(socket_, storage.addr, storage.addr_len);
+  result = bind(socket_, storage.addr, storage.addr_len);
   if (result < 0) {
     PLOG(ERROR) << "bind() returned an error";
     result = MapSystemError(WSAGetLastError());
     Close();
     return result;
   }
 
   result = listen(socket_, backlog);
   if (result < 0) {
     PLOG(ERROR) << "listen() returned an error";
@@ skipping 34 matching lines @@
     WSAEventSelect(socket_, socket_event_, FD_ACCEPT);
     accept_watcher_.StartWatching(socket_event_, this);
 
     accept_socket_ = socket;
     accept_callback_ = callback;
   }
 
   return result;
 }
 
+int TCPServerSocketWin::SetSocketOptions() {
+  BOOL true_value = 1;
+  if (reuse_address_) {
+    int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR,
+                        reinterpret_cast<const char*>(&true_value),
+                        sizeof(true_value));
+    if (rv < 0)
+      return MapSystemError(errno);
+  }
+  return OK;
+}
+
 int TCPServerSocketWin::AcceptInternal(scoped_ptr<StreamSocket>* socket) {
   SockaddrStorage storage;
   int new_socket = accept(socket_, storage.addr, &storage.addr_len);
   if (new_socket < 0) {
     int net_error = MapSystemError(WSAGetLastError());
     if (net_error != ERR_IO_PENDING)
       net_log_.EndEventWithNetErrorCode(NetLog::TYPE_TCP_ACCEPT, net_error);
     return net_error;
   }
 
@@ skipping 46 matching lines @@
     if (result != ERR_IO_PENDING) {
       accept_socket_ = NULL;
       CompletionCallback callback = accept_callback_;
       accept_callback_.Reset();
       callback.Run(result);
     }
   }
 }
 
 }  // namespace net