Multicast socket API

chrome/browser/extensions/api/socket/udp_socket.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 "chrome/browser/extensions/api/socket/udp_socket.h"
 
 #include "chrome/browser/extensions/api/api_resource.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_errors.h"
 #include "net/udp/datagram_socket.h"
@@ skipping 204 matching lines @@
   recv_from_callback_.Run(result, io_buffer, ip, port);
   recv_from_callback_.Reset();
 }
 
 void UDPSocket::OnSendToComplete(int result) {
   DCHECK(!send_to_callback_.is_null());
   send_to_callback_.Run(result);
   send_to_callback_.Reset();
 }
 
+int UDPSocket::JoinGroup(const std::string& address) {
+  if (!socket_.is_connected())
+    return net::ERR_SOCKET_NOT_CONNECTED;
+  net::IPAddressNumber ip;
+  if (!net::ParseIPLiteralToNumber(address, &ip))
+    return net::ERR_ADDRESS_INVALID;
+
+  std::string normalized_address = net::IPAddressToString(ip);
+  base::hash_set<std::string>::iterator find_result =
+      multicast_groups_.find(normalized_address);
+  if (find_result != multicast_groups_.end())
+    return net::ERR_ADDRESS_INVALID;
+
+  int rv = socket_.JoinGroup(ip);
+  if (rv == 0)
+    multicast_groups_.insert(normalized_address);
+  return rv;
+}
+
+int UDPSocket::LeaveGroup(const std::string& address) {
+  if (!socket_.is_connected())
+    return net::ERR_SOCKET_NOT_CONNECTED;
+  net::IPAddressNumber ip;
+  if (!net::ParseIPLiteralToNumber(address, &ip))
+    return net::ERR_ADDRESS_INVALID;
+
+  std::string normalized_address = net::IPAddressToString(ip);
+  base::hash_set<std::string>::iterator find_result =
+      multicast_groups_.find(normalized_address);
+  if (find_result == multicast_groups_.end())
+    return net::ERR_ADDRESS_INVALID;
+
+  int rv = socket_.LeaveGroup(ip);
+  if (rv == 0)
+    multicast_groups_.erase(find_result);
+  return rv;
+}
+
+int UDPSocket::SetMulticastTimeToLive(int ttl) {
+  if (socket_.is_connected())
+    return net::ERR_FAILED;

[wtc, 2013/04/22 19:19:53]

Please use net::ERR_UNEXPECTED here and on line 271. In general
we should use the most specific error code. ERR_FAILED is
very broad ("the function failed"). ERR_UNEXPECTED means
the function failed because of an unexpected reason (usually
a programming error). It's still not ideal, but is better
than ERR_FAILED.

But, why don't you just let socket_.SetMulticastTimeToLive()
and socket_.SetMulticastLoopbackMode() do this checking?

[Bei Zhang, 2013/04/23 17:26:53]

net::UDPSocket should be used internally. I think we should not check it in
net::UDPSocket in the Release build because we can control the way we use it. So
it only has a DCHECK on it.

On 2013/04/22 19:19:53, wtc wrote:

[wtc, 2013/04/23 18:01:07]

I see. Thank you for the explanation.

net::UDPSocket can be used by multiple components of Chrome.
Although net::UDPSocket is an internal class to the
extensions component, other components may not use it this
way. So I think it is better for net::UDPSocket to do
proper error checking, rather than relying on DCHECK only.

+  return socket_.SetMulticastTimeToLive(ttl);
+}
+
+int UDPSocket::SetMulticastLoopbackMode(bool loopback) {
+  if (socket_.is_connected())
+    return net::ERR_FAILED;
+  return socket_.SetMulticastLoopbackMode(loopback);
+}
+
+int UDPSocket::GetJoinedGroups(base::hash_set<std::string>* groups) const {
+  if (!socket_.is_connected())
+    return net::ERR_SOCKET_NOT_CONNECTED;
+  groups->clear();
+  groups->insert(multicast_groups_.begin(), multicast_groups_.end());
+  return 0;
+}
+
 }  // namespace extensions