Multicast socket API

net/udp/udp_socket_libevent.h

Index: net/udp/udp_socket_libevent.h
diff --git a/net/udp/udp_socket_libevent.h b/net/udp/udp_socket_libevent.h
index ce8a0f2269ad4c39dbe6f8b7e997216ecebde42a..f94c55beae647198db9b2912ff2d009ccfaa8277 100644
--- a/net/udp/udp_socket_libevent.h
+++ b/net/udp/udp_socket_libevent.h
@@ -5,6 +5,7 @@
 #ifndef NET_UDP_UDP_SOCKET_LIBEVENT_H_
 #define NET_UDP_UDP_SOCKET_LIBEVENT_H_
 
+#include "base/hash_tables.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/message_loop.h"
@@ -113,6 +114,29 @@ class NET_EXPORT UDPSocketLibevent : public base::NonThreadSafe {
   // called before Bind().
   void AllowBroadcast();
 
+  // Join the multicast group.
+  // |group_address| is the group address to join, could be either
+  // IPv4 or IPv6 address.
+  int JoinGroup(const net::IPAddressNumber& group_address) const;
+
+  // Leave the multicast group.
+  // |group_address| is the group address to leave, could be either
+  // 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.
+  int LeaveGroup(const net::IPAddressNumber& group_address) const;
+
+  // Set the time-to-live option for udp packets sent to the multicast
+  // group address. Initially this value is 1. Cannot be negative or
+  // more than 255.
+  int SetMulticastTimeToLive(int time_to_live);

[mmenke, 2013/04/16 18:09:49]

Think it's worth mentioned that this is safe to call either before or after the
socket is bound.

[Bei Zhang, 2013/04/17 17:53:03]

Please see comments in udp_socket_libevent.cc
On 2013/04/16 18:09:49, mmenke wrote:

+
+  // Set the loopback flag for udp socket. If this flag is true, the host
+  // will receive package sent to the joined group from itself.
+  // Initially this value is true.
+  int SetMulticastLoopbackMode(bool loopback);
+
  private:
   static const int kInvalidSocket = -1;
 
@@ -188,11 +212,17 @@ class NET_EXPORT UDPSocketLibevent : public base::NonThreadSafe {
   int RandomBind(const IPEndPoint& address);
 
   int socket_;
+  int sock_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 socket options cached for SetSocketOption.
+  // Cannot be used after Bind().
+  int multicast_time_to_live_;
+  bool multicast_loopback_mode_;
+
   // How to do source port binding, used only when UDPSocket is part of
   // UDPClientSocket, since UDPServerSocket provides Bind.
   DatagramSocket::BindType bind_type_;