Added broadcasting feature to UDP server sockets.

net/udp/udp_socket_libevent.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/udp/udp_socket_libevent.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <netdb.h>
 #include <sys/socket.h>
@@ skipping 23 matching lines @@
 }  // namespace net
 
 namespace net {
 
 UDPSocketLibevent::UDPSocketLibevent(
     DatagramSocket::BindType bind_type,
     const RandIntCallback& rand_int_cb,
     net::NetLog* net_log,
     const net::NetLog::Source& source)
         : socket_(kInvalidSocket),
+          allow_broadcast_(false),
           bind_type_(bind_type),
           rand_int_cb_(rand_int_cb),
           read_watcher_(this),
           write_watcher_(this),
           read_buf_len_(0),
           recv_from_address_(NULL),
           write_buf_len_(0),
           net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_UDP_SOCKET)) {
   net_log_.BeginEvent(NetLog::TYPE_SOCKET_ALIVE,
                       source.ToEventParametersCallback());
@@ skipping 190 matching lines @@
   remote_address_.reset(new IPEndPoint(address));
   return rv;
 }
 
 int UDPSocketLibevent::Bind(const IPEndPoint& address) {
   DCHECK(CalledOnValidThread());
   DCHECK(!is_connected());
   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;
   local_address_.reset();
   return rv;
 }
 
 bool UDPSocketLibevent::SetReceiveBufferSize(int32 size) {
   DCHECK(CalledOnValidThread());
   int rv = setsockopt(socket_, SOL_SOCKET, SO_RCVBUF,
                       reinterpret_cast<const char*>(&size), sizeof(size));
   DCHECK(!rv) << "Could not set socket receive buffer size: " << errno;
   return rv == 0;
 }
 
 bool UDPSocketLibevent::SetSendBufferSize(int32 size) {
   DCHECK(CalledOnValidThread());
   int rv = setsockopt(socket_, SOL_SOCKET, SO_SNDBUF,
                       reinterpret_cast<const char*>(&size), sizeof(size));
   DCHECK(!rv) << "Could not set socket send buffer size: " << errno;
   return rv == 0;
 }
 
+void UDPSocketLibevent::AllowBroadcast() {
+  DCHECK(CalledOnValidThread());
+  DCHECK(!is_connected());
+
+  allow_broadcast_ = true;
+}
+
 void UDPSocketLibevent::DoReadCallback(int rv) {
   DCHECK_NE(rv, ERR_IO_PENDING);
   DCHECK(!read_callback_.is_null());
 
   // since Run may result in Read being called, clear read_callback_ up front.
   CompletionCallback c = read_callback_;
   read_callback_.Reset();
   c.Run(rv);
 }
 
@@ skipping 136 matching lines @@
                             0,
                             addr,
                             storage.addr_len));
   if (result < 0)
     result = MapSystemError(errno);
   if (result != ERR_IO_PENDING)
     LogWrite(result, buf->data(), address);
   return result;
 }
 
+int UDPSocketLibevent::DoBroadcast() {
+  int true_value = 1;
+  int rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEADDR,
+                      reinterpret_cast<const char*>(&true_value),

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

Since the fourth argument to setsockopt is a const void* on Unix
(http://pubs.opengroup.org/onlinepubs/009695399/functions/setsockopt.html),
we should not need to cast &true_value to const char* here
and on lines 455 and 461.

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

Done.

+                      sizeof(true_value));
+  if (rv < 0)
+    return MapSystemError(errno);
+#if defined(OS_MACOSX)

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

If SO_REUSEPORT is defined as a macro (rather than an enum
constant) on Mac OS X, you can also test

    #if defined(SO_REUSEPORT)

here.  Then the code will automatically work on other platforms
that define the SO_REUSEPORT macro.

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

Done.

+  rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEPORT,
+                  reinterpret_cast<const char*>(&true_value),
+                  sizeof(true_value));
+  if (rv < 0)
+    return MapSystemError(errno);
+#endif
+  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 UDPSocketLibevent::DoBind(const IPEndPoint& address) {
   SockaddrStorage storage;
   if (!address.ToSockAddr(storage.addr, &storage.addr_len))
     return ERR_UNEXPECTED;
   int rv = bind(socket_, storage.addr, storage.addr_len);
   return rv < 0 ? MapSystemError(errno) : rv;
 }
 
 int UDPSocketLibevent::RandomBind(const IPEndPoint& address) {
   DCHECK(bind_type_ == DatagramSocket::RANDOM_BIND && !rand_int_cb_.is_null());
 
   // Construct IPAddressNumber of appropriate size (IPv4 or IPv6) of 0s.
   IPAddressNumber ip(address.address().size());
 
   for (int i = 0; i < kBindRetries; ++i) {
     int rv = DoBind(IPEndPoint(ip, rand_int_cb_.Run(kPortStart, kPortEnd)));
     if (rv == OK || rv != ERR_ADDRESS_IN_USE)
       return rv;
   }
   return DoBind(IPEndPoint(ip, 0));
 }
 
 }  // namespace net