Bind a socket to a network if the network handle is set.

webrtc/base/physicalsocketserver.cc

Index: webrtc/base/physicalsocketserver.cc
diff --git a/webrtc/base/physicalsocketserver.cc b/webrtc/base/physicalsocketserver.cc
index 524617221c894ee8d5530d4167f1a45ac9b3f387..9e54c49322e8ca35528eb4f297f10902cbc4aaa5 100644
--- a/webrtc/base/physicalsocketserver.cc
+++ b/webrtc/base/physicalsocketserver.cc
@@ -19,6 +19,7 @@
 #endif
 
 #if defined(WEBRTC_POSIX)
+#include <dlfcn.h>
 #include <string.h>
 #include <errno.h>
 #include <fcntl.h>
@@ -96,6 +97,14 @@ static const int ICMP_HEADER_SIZE = 8u;
 static const int ICMP_PING_TIMEOUT_MILLIS = 10000u;
 #endif
 
+static const int ERR_NOT_IMPLEMENTED = -11;
+
+#if defined(ANDROID) && !defined(WEBRTC_CHROMIUM_BUILD)
+static const int ERR_NETWORK_CHANGED = -21;
+static const int ERR_FAILED = -1;
+static const uint32_t INVALID_NETWORK_HANDLE = 0xFFFFFFFF;

[pthatcher1, 2016/01/06 21:58:46]

Where do these values come from?

[honghaiz3, 2016/01/12 20:36:42]

From the Chromium code. I changed them to an enum now. 

+#endif
+
 PhysicalSocket::PhysicalSocket(PhysicalSocketServer* ss, SOCKET s)
   : ss_(ss), s_(s), enabled_events_(0), error_(0),
     state_((s == INVALID_SOCKET) ? CS_CLOSED : CS_CONNECTED),
@@ -177,6 +186,49 @@ int PhysicalSocket::Bind(const SocketAddress& bind_addr) {
   return err;
 }
 
+int PhysicalSocket::BindToNetwork(NetworkHandle network) {
+#if defined(ANDROID) && !defined(WEBRTC_CHROMIUM_BUILD)
+  LOG(LS_INFO) << "Bind socket " << s_ << " to network handle " << network;
+  // Android prior to Lollipop didn't have support for binding sockets to
+  // networks. However, it should not have reached here in that case
+  // because the default network handle is invalid.
+  ASSERT(network != INVALID_NETWORK_HANDLE);
+
+  // NOTE: This does rely on Android implementation details, but
+  // these details are unlikely to change.
+  typedef int (*SetNetworkForSocket)(unsigned netId, int socketFd);
+  static SetNetworkForSocket setNetworkForSocket;
+  // This is racy, but all racers should come out with the same answer so it
+  // shouldn't matter.
+  if (setNetworkForSocket == nullptr) {
+    // Android's netd client library should always be loaded in our address
+    // space as it shims libc functions like connect().
+    const std::string net_library_path = "libnetd_client.so";
+    void* lib = dlopen(net_library_path.c_str(), RTLD_LAZY);
+    if (lib == nullptr) {
+      LOG(LS_ERROR) << "Library " << net_library_path << " not found!";
+      return ERR_NOT_IMPLEMENTED;
+    }
+    setNetworkForSocket = reinterpret_cast<SetNetworkForSocket>(
+        dlsym(lib, "setNetworkForSocket"));
+  }
+  if (setNetworkForSocket == nullptr) {
+    LOG(LS_ERROR) << "Symbol setNetworkForSocket not found ";
+    return ERR_NOT_IMPLEMENTED;
+  }
+  int rv = setNetworkForSocket(network, s_);
+  // If |network| has since disconnected, |rv| will be ENONET.  Surface this as
+  // ERR_NETWORK_CHANGED, rather than MapSystemError(ENONET) which gives back
+  // the less descriptive ERR_FAILED.
+  if (rv == ENONET)
+    return ERR_NETWORK_CHANGED;
+  return ERR_FAILED;

[pthatcher1, 2016/01/06 21:58:46]

For readability, can you move this into its own Android-specific function,
something like BindAndroidSocketToNetwork?

[honghaiz3, 2016/01/12 20:36:42]

Done.

+#else
+  ASSERT(false);
+  return ERR_NOT_IMPLEMENTED;
+#endif
+}
+
 int PhysicalSocket::Connect(const SocketAddress& addr) {
   // TODO(pthatcher): Implicit creation is required to reconnect...
   // ...but should we make it more explicit?
@@ -1127,7 +1179,7 @@ bool SocketDispatcher::CheckSignalClose() {
 
 int SocketDispatcher::next_id_ = 0;
 
-#endif  // WEBRTC_WIN 
+#endif  // WEBRTC_WIN
 
 // Sets the value of a boolean value to false when signaled.
 class Signaler : public EventDispatcher {
@@ -1621,6 +1673,6 @@ bool PhysicalSocketServer::Wait(int cmsWait, bool process_io) {
   // Done
   return true;
 }
-#endif  // WEBRTC_WIN 
+#endif  // WEBRTC_WIN
 
 }  // namespace rtc