Multicast socket API

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),
+          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),
           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 301 matching lines @@
         CreateNetLogUDPDataTranferCallback(
             result, bytes,
             is_address_valid ? &address : NULL));
   }
 
   base::StatsCounter read_bytes("udp.read_bytes");
   read_bytes.Add(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_)) {
     const int err = MapSystemError(errno);
     Close();
     return err;
   }
   return OK;
 }
 
@@ skipping 92 matching lines @@
       return MapSystemError(errno);
   }
   if (socket_options_ & SOCKET_OPTION_BROADCAST) {
     int rv;
 #if defined(OS_MACOSX)
     // SO_REUSEPORT on OSX permits multiple processes to each receive
     // UDP multicast or broadcast datagrams destined for the bound
     // port.
     rv = setsockopt(socket_, SOL_SOCKET, SO_REUSEPORT, &true_value,
                     sizeof(true_value));
+#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);
-#endif  // defined(OS_MACOSX)
-    rv = setsockopt(socket_, SOL_SOCKET, SO_BROADCAST, &true_value,
-                    sizeof(true_value));
-    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;
 }
 
 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));
 }
 
+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