Added broadcasting feature to UDP server sockets.

net/udp/udp_socket_win.cc

Index: net/udp/udp_socket_win.cc
diff --git a/net/udp/udp_socket_win.cc b/net/udp/udp_socket_win.cc
index a7a11bf32f17e6829eab71273fb1f1556d618f86..2f25a231a0163c7c0da945e8a759de4850ed4b1a 100644
--- a/net/udp/udp_socket_win.cc
+++ b/net/udp/udp_socket_win.cc
@@ -46,6 +46,7 @@ UDPSocketWin::UDPSocketWin(DatagramSocket::BindType bind_type,
                            net::NetLog* net_log,
                            const net::NetLog::Source& source)
     : socket_(INVALID_SOCKET),
+      allow_broadcast_(false),
       bind_type_(bind_type),
       rand_int_cb_(rand_int_cb),
       ALLOW_THIS_IN_INITIALIZER_LIST(read_delegate_(this)),
@@ -229,6 +230,11 @@ int UDPSocketWin::Bind(const IPEndPoint& address) {
   int rv = CreateSocket(address);
   if (rv < 0)
     return rv;
+  if (allow_broadcast_) {
+    rv = DoBroadcast();
+    if (rv < 0)
+      return rv;
+  }
   rv = DoBind(address);
   if (rv < 0)
     return rv;
@@ -260,6 +266,13 @@ bool UDPSocketWin::SetSendBufferSize(int32 size) {
   return rv == 0;
 }
 
+void UDPSocketWin::AllowBroadcast() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!is_connected());
+
+  allow_broadcast_ = true;
+}
+
 void UDPSocketWin::DoReadCallback(int rv) {
   DCHECK_NE(rv, ERR_IO_PENDING);
   DCHECK(!read_callback_.is_null());
@@ -431,6 +444,21 @@ int UDPSocketWin::InternalSendTo(IOBuffer* buf, int buf_len,
   return ERR_IO_PENDING;
 }
 
+int UDPSocketWin::DoBroadcast() {
+  int true_value = 1;

[wtc, 2012/07/11 18:26:37]

It looks nicer to use the BOOL type here:
http://msdn.microsoft.com/en-us/library/windows/desktop/ms740476(v=vs.85).aspx

BOOL and int have the same size on Windows, so this doesn't
really matter.

The fourth argument to setsockopt is a const char* on Windows,
so the casts to const char* are necessary in this file.

[ygorshenin1, 2012/07/12 09:28:08]

Done.

+  int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR,
+                      reinterpret_cast<const char*>(&true_value),
+                      sizeof(true_value));
+  if (rv < 0)
+    return MapSystemError(errno);
+  rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST,
+                  reinterpret_cast<const char*>(&true_value),
+                  sizeof(true_value));
+  if (rv < 0)
+    return MapSystemError(errno);
+  return OK;
+}
+
 int UDPSocketWin::DoBind(const IPEndPoint& address) {
   SockaddrStorage storage;
   if (!address.ToSockAddr(storage.addr, &storage.addr_len))