Add support of IP_MULTICAST_IF in UDP 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 24 matching lines @@
 namespace net {
 
 UDPSocketLibevent::UDPSocketLibevent(
     DatagramSocket::BindType bind_type,
     const RandIntCallback& rand_int_cb,
     net::NetLog* net_log,
     const net::NetLog::Source& source)
         : socket_(kInvalidSocket),
           addr_family_(0),
           socket_options_(SOCKET_OPTION_MULTICAST_LOOP),
+          multicast_interface_(0),
           multicast_time_to_live_(1),
           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,
@@ skipping 470 matching lines @@
                       &ttl, sizeof(ttl));
     } else {
       // Signed interger. -1 to use route default.
       int ttl = multicast_time_to_live_;
       rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_MULTICAST_HOPS,
                       &ttl, sizeof(ttl));
     }
     if (rv < 0)
       return MapSystemError(errno);
   }
+  if (multicast_interface_ != 0) {
+    switch (addr_family_) {
+      case AF_INET: {
+        in_addr address;
+        address.s_addr = htonl(multicast_interface_);

[Noam Samuel, 2013/12/02 22:05:54]

I know that the 0.x.x.x address convention for numbered interfaces is used in
Windows, but are you sure it exists in Linux/Mac OSX?

[szym, 2013/12/03 07:42:11]

In Linux, IP_MULTICAST_IF option has to be one of:
struct in_addr
struct ip_mreq
struct ip_mreqn

In the first two, the interface is looked up by IP address (ip_dev_find). In the
last one, if imr_ifindex is non-zero, then it is used as the interface index
(dev_get_by_index).

See: http://lxr.free-electrons.com/source/net/ipv4/ip_sockglue.c#L666

+        int rv = setsockopt(socket_, IPPROTO_IP, IP_MULTICAST_IF,
+                            reinterpret_cast<const char*>(&address),
+                            sizeof(address));
+        if (rv)
+          return MapSystemError(errno);
+        break;
+      }
+      case AF_INET6: {
+        uint32 interface_index = multicast_interface_;
+        int rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_MULTICAST_IF,
+                            reinterpret_cast<const char*>(&interface_index),
+                            sizeof(interface_index));
+        if (rv)
+          return MapSystemError(errno);
+        break;
+      }
+      default:
+        NOTREACHED() << "Invalid address family";
+        return ERR_ADDRESS_INVALID;
+    }
+  }
   return OK;
 }
 
 int UDPSocketLibevent::DoBind(const IPEndPoint& address) {
   SockaddrStorage storage;
   if (!address.ToSockAddr(storage.addr, &storage.addr_len))
     return ERR_ADDRESS_INVALID;
   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));
 }
 
-int UDPSocketLibevent::JoinGroup(const IPAddressNumber& group_address) const {
+int UDPSocketLibevent::JoinGroup(const IPAddressNumber& group_address) {
   DCHECK(CalledOnValidThread());
   if (!is_connected())
     return ERR_SOCKET_NOT_CONNECTED;
 
   switch (group_address.size()) {
     case kIPv4AddressSize: {
       if (addr_family_ != AF_INET)
         return ERR_ADDRESS_INVALID;
       ip_mreq mreq;
-      mreq.imr_interface.s_addr = INADDR_ANY;
+      mreq.imr_interface.s_addr = htonl(multicast_interface_);

[Noam Samuel, 2013/12/02 22:05:54]

Same question

       memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);
       int rv = setsockopt(socket_, IPPROTO_IP, IP_ADD_MEMBERSHIP,
                           &mreq, sizeof(mreq));
       if (rv < 0)
         return MapSystemError(errno);
       return OK;
     }
     case kIPv6AddressSize: {
       if (addr_family_ != AF_INET6)
         return ERR_ADDRESS_INVALID;
       ipv6_mreq mreq;
-      mreq.ipv6mr_interface = 0;  // 0 indicates default multicast interface.
+      mreq.ipv6mr_interface = multicast_interface_;
       memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
       int rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_JOIN_GROUP,
                           &mreq, sizeof(mreq));
       if (rv < 0)
         return MapSystemError(errno);
       return OK;
     }
     default:
       NOTREACHED() << "Invalid address family";
       return ERR_ADDRESS_INVALID;
   }
 }
 
-int UDPSocketLibevent::LeaveGroup(const IPAddressNumber& group_address) const {
+int UDPSocketLibevent::LeaveGroup(const IPAddressNumber& group_address) {
   DCHECK(CalledOnValidThread());
 
   if (!is_connected())
     return ERR_SOCKET_NOT_CONNECTED;
 
   switch (group_address.size()) {
     case kIPv4AddressSize: {
       if (addr_family_ != AF_INET)
         return ERR_ADDRESS_INVALID;
       ip_mreq mreq;
@@ skipping 16 matching lines @@
       if (rv < 0)
         return MapSystemError(errno);
       return OK;
     }
     default:
       NOTREACHED() << "Invalid address family";
       return ERR_ADDRESS_INVALID;
   }
 }
 
+int UDPSocketLibevent::SetMulticastInterface(uint32 interface_index) {
+  DCHECK(CalledOnValidThread());
+  if (is_connected())
+    return ERR_SOCKET_IS_CONNECTED;
+  multicast_interface_ = interface_index;
+  return OK;
+}
+
 int UDPSocketLibevent::SetMulticastTimeToLive(int time_to_live) {
   DCHECK(CalledOnValidThread());
   if (is_connected())
     return ERR_SOCKET_IS_CONNECTED;
 
   if (time_to_live < 0 || time_to_live > 255)
     return ERR_INVALID_ARGUMENT;
   multicast_time_to_live_ = time_to_live;
   return OK;
 }
@@ skipping 23 matching lines @@
     rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_TCLASS,
                     &dscp_and_ecn, sizeof(dscp_and_ecn));
   }
   if (rv < 0)
     return MapSystemError(errno);
 
   return OK;
 }
 
 }  // namespace net