Add support for default local address in IpcNetworkManager

content/browser/renderer_host/p2p/socket_dispatcher_host.cc

Index: content/browser/renderer_host/p2p/socket_dispatcher_host.cc
diff --git a/content/browser/renderer_host/p2p/socket_dispatcher_host.cc b/content/browser/renderer_host/p2p/socket_dispatcher_host.cc
index c450d31964a916ea511e74735d8ae263b38d4478..f93f3c3add7a1154daf5a42927b4b5bb9d74cec4 100644
--- a/content/browser/renderer_host/p2p/socket_dispatcher_host.cc
+++ b/content/browser/renderer_host/p2p/socket_dispatcher_host.cc
@@ -8,6 +8,7 @@
 #include "base/stl_util.h"
 #include "content/browser/renderer_host/p2p/socket_host.h"
 #include "content/common/p2p_messages.h"
+#include "content/public/browser/browser_thread.h"
 #include "content/public/browser/resource_context.h"
 #include "net/base/address_list.h"
 #include "net/base/completion_callback.h"
@@ -16,6 +17,7 @@
 #include "net/base/sys_addrinfo.h"
 #include "net/dns/single_request_host_resolver.h"
 #include "net/log/net_log.h"
+#include "net/udp/udp_client_socket.h"
 #include "net/url_request/url_request_context_getter.h"
 
 using content::BrowserMessageFilter;
@@ -23,6 +25,16 @@ using content::BrowserThread;
 
 namespace content {
 
+namespace {
+
+// Used by GetDefaultLocalAddress as the target to connect to for getting the
+// default local address. They are public DNS servers on the internet.
+const char kPublicIPv4Host[] = "8.8.8.8";
+const char kPublicIPv6Host[] = "[2001:4860:4860::8888]";
+const int kPublicPort = 53;  // DNS port.
+
+}  // namespace
+
 const size_t kMaximumPacketSize = 32768;
 
 class P2PSocketDispatcherHost::DnsRequest {
@@ -321,14 +333,52 @@ void P2PSocketDispatcherHost::OnDestroySocket(int socket_id) {
 void P2PSocketDispatcherHost::DoGetNetworkList() {
   net::NetworkInterfaceList list;
   net::GetNetworkList(&list, net::EXCLUDE_HOST_SCOPE_VIRTUAL_INTERFACES);
+  default_ipv4_local_address_ = GetDefaultLocalAddress(AF_INET);
+  default_ipv6_local_address_ = GetDefaultLocalAddress(AF_INET6);
   BrowserThread::PostTask(
-      BrowserThread::IO, FROM_HERE, base::Bind(
-          &P2PSocketDispatcherHost::SendNetworkList, this, list));
+      BrowserThread::IO, FROM_HERE,
+      base::Bind(&P2PSocketDispatcherHost::SendNetworkList, this, list,
+                 default_ipv4_local_address_, default_ipv6_local_address_));
 }
 
 void P2PSocketDispatcherHost::SendNetworkList(
-    const net::NetworkInterfaceList& list) {
-  Send(new P2PMsg_NetworkListChanged(list));
+    const net::NetworkInterfaceList& list,
+    const net::IPEndPoint& default_ipv4_local_address,
+    const net::IPEndPoint& default_ipv6_local_address) {
+  Send(new P2PMsg_NetworkListChanged(list, default_ipv4_local_address,
+                                     default_ipv6_local_address));
+}
+
+net::IPEndPoint P2PSocketDispatcherHost::GetDefaultLocalAddress(int family) {
+  DCHECK(family == AF_INET || family == AF_INET6);
+
+  // Please see crbug.com/455942. We want to make sure we're not on these 2

[Sergey Ulanov, 2015/11/10 22:44:17]

This bug reference is confusing here - the bug is about DNS resolution being
janky. Just say in the comments that creation and connection of UDP socket may
be janky. The bug you are referring to is just an example of such jank.

[guoweis_webrtc, 2015/11/11 00:11:51]

Done.

+  // threads.
+  DCHECK(!::content::BrowserThread::CurrentlyOn(BrowserThread::UI));

[Sergey Ulanov, 2015/11/10 22:44:16]

This code is always called on the FILE thread, so maybe just DCHECK it here?

[guoweis_webrtc, 2015/11/11 00:11:51]

Done.

+  DCHECK(!::content::BrowserThread::CurrentlyOn(BrowserThread::IO));
+
+  net::IPEndPoint local_address;

[Sergey Ulanov, 2015/11/10 22:44:16]

nit: Move this just before GetLocalAddress() call below.

[guoweis_webrtc, 2015/11/11 00:11:51]

Done.

+  net::IPAddressNumber ip_address_number;
+
+  scoped_ptr<net::UDPClientSocket> socket(new net::UDPClientSocket(

[Sergey Ulanov, 2015/11/10 22:44:16]

Please use
net::ClientSocketFactory::GetDefaultFactory()->CreateDatagramClientSocket() to
create UDP sockets.

[guoweis_webrtc, 2015/11/11 00:11:51]

Done.

+      net::DatagramSocket::DEFAULT_BIND, net::RandIntCallback(), NULL,
+      net::NetLog::Source()));
+
+  if (!net::ParseURLHostnameToNumber(

[Sergey Ulanov, 2015/11/10 22:44:16]

net::IPAddressNumber is just an std::vector<uint8_t>. So instead of parsing the
strings you can store the target addresses as arrays of integers and initialize
the addresses from these arrays.

[guoweis_webrtc, 2015/11/11 00:11:51]

Done.

+          family == AF_INET ? kPublicIPv4Host : kPublicIPv6Host,
+          &ip_address_number)) {
+    return net::IPEndPoint();

[Sergey Ulanov, 2015/11/10 22:44:16]

this would need to be marked NOTREACHED(), but it doesn't matter if you take my
suggestion above.

[guoweis_webrtc, 2015/11/11 00:11:51]

Done.

+  }
+
+  if (socket->Connect(net::IPEndPoint(ip_address_number, kPublicPort)) !=
+      net::OK) {
+    return net::IPEndPoint();
+  }
+
+  if (socket->GetLocalAddress(&local_address) != net::OK)
+    return net::IPEndPoint();
+
+  return local_address;
 }
 
 void P2PSocketDispatcherHost::OnAddressResolved(