Add support of IP_MULTICAST_IF in UDP sockets.

net/udp/udp_socket_libevent.h

 // 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.
 
 #ifndef NET_UDP_UDP_SOCKET_LIBEVENT_H_
 #define NET_UDP_UDP_SOCKET_LIBEVENT_H_
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop/message_loop.h"
@@ skipping 111 matching lines @@
 
   // Leave the multicast group.
   // |group_address| is the group address to leave, could be either
   // an IPv4 or IPv6 address. If the socket hasn't joined the group,
   // it will be ignored.
   // It's optional to leave the multicast group before destroying
   // the socket. It will be done by the OS.
   // Return a network error code.
   int LeaveGroup(const IPAddressNumber& group_address) const;
 
+  // Set interface to use for multicast. If |interface_index| set to 0, default
+  // interface is used.
+  // Should be called before Bind().
+  // Returns a network error code.
+  int SetMulticastInterface(uint32 interface_index);
+
   // Set the time-to-live option for UDP packets sent to the multicast
   // group address. The default value of this option is 1.
   // Cannot be negative or more than 255.
   // Should be called before Bind().
   // Return a network error code.
   int SetMulticastTimeToLive(int time_to_live);
 
   // Set the loopback flag for UDP socket. If this flag is true, the host
   // will receive packets sent to the joined group from itself.
   // The default value of this option is true.
@@ skipping 88 matching lines @@
   int DoBind(const IPEndPoint& address);
   int RandomBind(const IPEndPoint& address);
 
   int socket_;
   int addr_family_;
 
   // Bitwise-or'd combination of SocketOptions. Specifies the set of
   // options that should be applied to |socket_| before Bind().
   int socket_options_;
 
+  // Multicast interface.
+  uint32 multicast_interface_;
+
   // Multicast socket options cached for SetSocketOption.
   // Cannot be used after Bind().
   int multicast_time_to_live_;
 
   // How to do source port binding, used only when UDPSocket is part of
   // UDPClientSocket, since UDPServerSocket provides Bind.
   DatagramSocket::BindType bind_type_;
 
   // PRNG function for generating port numbers.
   RandIntCallback rand_int_cb_;
@@ skipping 28 matching lines @@
   CompletionCallback write_callback_;
 
   BoundNetLog net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(UDPSocketLibevent);
 };
 
 }  // namespace net
 
 #endif  // NET_UDP_UDP_SOCKET_LIBEVENT_H_