Multicast socket API

net/udp/udp_socket_libevent.cc

Index: net/udp/udp_socket_libevent.cc
diff --git a/net/udp/udp_socket_libevent.cc b/net/udp/udp_socket_libevent.cc
index 063da08c387963b60066b3d1459aa82b9703a970..1c0f80d5b7bf5ef4c67416741e3f277b7243782f 100644
--- a/net/udp/udp_socket_libevent.cc
+++ b/net/udp/udp_socket_libevent.cc
@@ -41,7 +41,10 @@ UDPSocketLibevent::UDPSocketLibevent(
     net::NetLog* net_log,
     const net::NetLog::Source& source)
         : socket_(kInvalidSocket),
+          sock_addr_family_(0),
           socket_options_(0),
+          multicast_time_to_live_(1),
+          multicast_loopback_mode_(true),
           bind_type_(bind_type),
           rand_int_cb_(rand_int_cb),
           read_watcher_(this),
@@ -363,7 +366,8 @@ void UDPSocketLibevent::LogRead(int result,
 }
 
 int UDPSocketLibevent::CreateSocket(const IPEndPoint& address) {
-  socket_ = socket(address.GetSockAddrFamily(), SOCK_DGRAM, 0);
+  sock_addr_family_ = address.GetSockAddrFamily();
+  socket_ = socket(sock_addr_family_, SOCK_DGRAM, 0);
   if (socket_ == kInvalidSocket)
     return MapSystemError(errno);
   if (SetNonBlocking(socket_)) {
@@ -476,14 +480,23 @@ int UDPSocketLibevent::SetSocketOptions() {
     // port.
     rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEPORT, &true_value,
                     sizeof(true_value));
-    if (rv < 0)
-      return MapSystemError(errno);
-#endif  // defined(OS_MACOSX)
+#else
     rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST, &true_value,
                     sizeof(true_value));

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

This needs to be done on OSX, too.

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

It's done in the other #if branch.

+#endif  // defined(OS_MACOSX)
     if (rv < 0)
       return MapSystemError(errno);
   }
+  if (multicast_time_to_live_ != 1) {
+    int rv = SetMulticastTimeToLive(multicast_time_to_live_);
+    if (rv != OK)
+      return rv;
+  }
+  if (!multicast_loopback_mode_) {
+    int rv = SetMulticastLoopbackMode(multicast_loopback_mode_);
+    if (rv != OK)
+      return rv;
+  }
   return OK;
 }
 
@@ -509,4 +522,99 @@ int UDPSocketLibevent::RandomBind(const IPEndPoint& address) {
   return DoBind(IPEndPoint(ip, 0));
 }
 
+int UDPSocketLibevent::JoinGroup(
+    const net::IPAddressNumber& group_address) const {
+  DCHECK(CalledOnValidThread());
+  DCHECK(is_connected());
+
+  int rv = -1;

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

Sending a -1 through MapSystemError on fall through seems rather random to me.

My suggestion is to have:

default:
  NOTREACHED();
  return ERR_INVALID_ARGUMENT;

in the switch statement instead.

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

Done.

+  switch (group_address.size()) {
+    case kIPv4AddressSize: {
+      if (sock_addr_family_ != AF_INET)
+        return ERR_ADDRESS_INVALID;
+      ip_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);

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

Seems like we should be explicitely using IN_ADDRANY for mreq.imr_interface.

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

Done.

+      rv = setsockopt(socket_, IPPROTO_IP, IP_ADD_MEMBERSHIP,
+                      &mreq, sizeof(mreq));
+      break;
+    }
+    case kIPv6AddressSize: {
+      if (sock_addr_family_ != AF_INET6)
+        return ERR_ADDRESS_INVALID;
+      ipv6_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_JOIN_GROUP,
+                      &mreq, sizeof(mreq));

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

Seems like we should be explicitely using in6addr_any for mreq.imr_interface.

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

Done.

+      break;
+    }
+  }
+
+  return MapSystemError(rv);
+}
+
+int UDPSocketLibevent::LeaveGroup(
+    const net::IPAddressNumber& group_address) const {
+  DCHECK(CalledOnValidThread());
+  DCHECK(is_connected());
+
+  int rv = -1;
+  switch (group_address.size()) {
+    case kIPv4AddressSize: {
+      if (sock_addr_family_ != AF_INET)
+        return ERR_ADDRESS_INVALID;
+      ip_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.imr_multiaddr, &group_address[0], kIPv4AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IP, IP_DROP_MEMBERSHIP,
+                      &mreq, sizeof(mreq));
+      break;
+    }
+    case kIPv6AddressSize: {
+      if (sock_addr_family_ != AF_INET6)
+        return ERR_ADDRESS_INVALID;
+      ipv6_mreq mreq;
+      memset(&mreq, 0, sizeof(mreq));
+      memcpy(&mreq.ipv6mr_multiaddr, &group_address[0], kIPv6AddressSize);
+      rv = setsockopt(socket_, IPPROTO_IPV6, IPV6_LEAVE_GROUP,
+                      &mreq, sizeof(mreq));
+      break;
+    }
+  }
+
+  return MapSystemError(rv);
+}
+
+int UDPSocketLibevent::SetMulticastTimeToLive(int time_to_live) {
+  DCHECK(CalledOnValidThread());
+  if (time_to_live < 0 || time_to_live > 255)
+    return ERR_INVALID_ARGUMENT;
+  if (is_connected()) {

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

Do we need these to be dynamically configurable?  My only contern here is that
makes for an inconsistent API, as everything else has to be set before bind,
which I think makes for a confusing API.

If it is needed, seems like we should be setting multicast_loopback_mode_ on
success, to be consistent.  Can easily see someone expecting
multicast_time_to_live_ to be accurate in a future CL.

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

I thought about this for a while. I think you are right, I cannot think of a
scenario that user cannot do this before bind/connect. Changing it now.

On 2013/04/16 18:09:49, mmenke wrote:

+    uint8 ttl = time_to_live;
+    int ip_family = sock_addr_family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
+    return MapSystemError(setsockopt(socket_,
+        ip_family,
+        IP_MULTICAST_TTL,
+        &ttl, sizeof(ttl)));
+  } else {

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

Preferred style in Chrome is not to have an else here, as it's not needed.

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

Done.

+    multicast_time_to_live_ = time_to_live;
+    return OK;
+  }
+}
+
+int UDPSocketLibevent::SetMulticastLoopbackMode(bool loopback) {
+  DCHECK(CalledOnValidThread());
+  if (is_connected()) {
+    uint8 loop = loopback;
+    int ip_family = sock_addr_family_ == AF_INET ? IPPROTO_IP : IPPROTO_IPV6;
+    return MapSystemError(setsockopt(socket_,
+        ip_family,
+        IP_MULTICAST_LOOP,
+        &loop, sizeof(loop)));
+  } else {
+    multicast_loopback_mode_ = loopback;
+    return OK;
+  }
+}
 }  // namespace net