Migrates QUIC sessions to a new network when old network is (about to be) disconnected.

net/quic/quic_stream_factory.cc

Index: net/quic/quic_stream_factory.cc
diff --git a/net/quic/quic_stream_factory.cc b/net/quic/quic_stream_factory.cc
index 976cfcf46f76527c065f26b6a22e207b3ea111f6..f5b0163745449399e991a1a861c409db1d1716ad 100644
--- a/net/quic/quic_stream_factory.cc
+++ b/net/quic/quic_stream_factory.cc
@@ -71,6 +71,15 @@ enum CreateSessionFailure {
   CREATION_ERROR_MAX
 };
 
+enum QuicConnectionMigrationStatus {
+  MIGRATION_STATUS_NO_MIGRATABLE_STREAMS,
+  MIGRATION_STATUS_ALREADY_MIGRATED,
+  MIGRATION_STATUS_INTERNAL_ERROR,
+  MIGRATION_STATUS_TOO_MANY_CHANGES,
+  MIGRATION_STATUS_SUCCESS,
+  MIGRATION_STATUS_MAX
+};
+
 // The maximum receive window sizes for QUIC sessions and streams.
 const int32_t kQuicSessionMaxRecvWindowSize = 15 * 1024 * 1024;  // 15 MB
 const int32_t kQuicStreamMaxRecvWindowSize = 6 * 1024 * 1024;    // 6 MB
@@ -83,6 +92,11 @@ void HistogramCreateSessionFailure(enum CreateSessionFailure error) {
                             CREATION_ERROR_MAX);
 }
 
+void HistogramMigrationStatus(enum QuicConnectionMigrationStatus status) {
+  UMA_HISTOGRAM_ENUMERATION("Net.QuicSession.ConnectionMigration", status,
+                            MIGRATION_STATUS_MAX);
+}
+
 bool IsEcdsaSupported() {
 #if defined(OS_WIN)
   if (base::win::GetVersion() < base::win::VERSION_VISTA)
@@ -572,6 +586,7 @@ QuicStreamFactory::QuicStreamFactory(
     bool store_server_configs_in_properties,
     bool close_sessions_on_ip_change,
     int idle_connection_timeout_seconds,
+    bool migrate_sessions_on_network_change,
     const QuicTagVector& connection_options)
     : require_confirmation_(true),
       host_resolver_(host_resolver),
@@ -619,6 +634,9 @@ QuicStreamFactory::QuicStreamFactory(
           kQuicYieldAfterDurationMilliseconds)),
       store_server_configs_in_properties_(store_server_configs_in_properties),
       close_sessions_on_ip_change_(close_sessions_on_ip_change),
+      migrate_sessions_on_network_change_(
+          migrate_sessions_on_network_change &&
+          NetworkChangeNotifier::AreNetworkHandlesSupported()),
       port_seed_(random_generator_->RandUint64()),
       check_persisted_supports_quic_(true),
       has_initialized_data_(false),
@@ -657,13 +675,17 @@ QuicStreamFactory::QuicStreamFactory(
         new PropertiesBasedQuicServerInfoFactory(http_server_properties_));
   }
 
-  if (close_sessions_on_ip_change_) {
+  DCHECK(
+      !(close_sessions_on_ip_change_ && migrate_sessions_on_network_change_));
+  if (migrate_sessions_on_network_change_) {
+    NetworkChangeNotifier::AddNetworkObserver(this);
+  } else if (close_sessions_on_ip_change_) {
     NetworkChangeNotifier::AddIPAddressObserver(this);
   }
 }
 
 QuicStreamFactory::~QuicStreamFactory() {
-  CloseAllSessions(ERR_ABORTED);
+  CloseAllSessions(ERR_ABORTED, QUIC_INTERNAL_ERROR);
   while (!all_sessions_.empty()) {
     delete all_sessions_.begin()->first;
     all_sessions_.erase(all_sessions_.begin());
@@ -673,7 +695,9 @@ QuicStreamFactory::~QuicStreamFactory() {
     STLDeleteElements(&(active_jobs_[server_id]));
     active_jobs_.erase(server_id);
   }
-  if (close_sessions_on_ip_change_) {
+  if (migrate_sessions_on_network_change_) {
+    NetworkChangeNotifier::RemoveNetworkObserver(this);
+  } else if (close_sessions_on_ip_change_) {
     NetworkChangeNotifier::RemoveIPAddressObserver(this);
   }
 }
@@ -1099,17 +1123,15 @@ void QuicStreamFactory::CancelRequest(QuicStreamRequest* request) {
   active_requests_.erase(request);
 }
 
-void QuicStreamFactory::CloseAllSessions(int error) {
+void QuicStreamFactory::CloseAllSessions(int error, QuicErrorCode quic_error) {
   while (!active_sessions_.empty()) {
     size_t initial_size = active_sessions_.size();
-    active_sessions_.begin()->second->CloseSessionOnError(error,
-                                                          QUIC_INTERNAL_ERROR);
+    active_sessions_.begin()->second->CloseSessionOnError(error, quic_error);
     DCHECK_NE(initial_size, active_sessions_.size());
   }
   while (!all_sessions_.empty()) {
     size_t initial_size = all_sessions_.size();
-    all_sessions_.begin()->first->CloseSessionOnError(error,
-                                                      QUIC_INTERNAL_ERROR);
+    all_sessions_.begin()->first->CloseSessionOnError(error, quic_error);
     DCHECK_NE(initial_size, all_sessions_.size());
   }
   DCHECK(all_sessions_.empty());
@@ -1142,16 +1164,113 @@ void QuicStreamFactory::ClearCachedStatesInCryptoConfig() {
 }
 
 void QuicStreamFactory::OnIPAddressChanged() {
-  CloseAllSessions(ERR_NETWORK_CHANGED);
+  CloseAllSessions(ERR_NETWORK_CHANGED, QUIC_IP_ADDRESS_CHANGED);
   set_require_confirmation(true);
 }
 
+void QuicStreamFactory::OnNetworkConnected(
+    NetworkChangeNotifier::NetworkHandle network) {}
+
+void QuicStreamFactory::OnNetworkMadeDefault(
+    NetworkChangeNotifier::NetworkHandle network) {}
+
+void QuicStreamFactory::OnNetworkDisconnected(
+    NetworkChangeNotifier::NetworkHandle network) {
+  MaybeMigrateOrCloseSessions(network, /*force_close=*/true);
+  set_require_confirmation(true);
+}
+
+void QuicStreamFactory::OnNetworkSoonToDisconnect(

[Ryan Hamilton, 2015/12/29 05:29:36]

Can you add a comment here about this method not being called when going from
WiFi to cellular. (Or perhaps a more general comment)

[Jana, 2016/01/06 23:01:17]

I've copied comments from the network change notifier.

[Ryan Hamilton, 2016/01/08 05:01:06]

Perhaps I'm not reading carefully, but I don't seen anything (even in the .h
file) which says that it won't be called when going from WiFi to cellular. I'd
be inclined to add a comment here (in the .cc file, near the implementation of
this method) as a reminder to future readers.

[Jana, 2016/01/09 02:06:53]

Done.

+    NetworkChangeNotifier::NetworkHandle network) {
+  MaybeMigrateOrCloseSessions(network, /*force_close=*/false);
+}
+
+void QuicStreamFactory::MaybeMigrateOrCloseSessions(
+    NetworkChangeNotifier::NetworkHandle network,
+    bool force_close) {
+  DCHECK_NE(NetworkChangeNotifier::kInvalidNetworkHandle, network);
+
+  // Find a new network that sessions bound to |network| can be migrated to.
+  NetworkChangeNotifier::NetworkList network_list;
+  NetworkChangeNotifier::GetConnectedNetworks(&network_list);

[Ryan Hamilton, 2015/12/29 05:29:36]

(Why does this method not return a NetworkList?)

[Jana, 2016/01/06 23:01:17]

Not sure... I don't remember why this was designed this way. Paul?

+  NetworkChangeNotifier::NetworkHandle new_network =
+      NetworkChangeNotifier::kInvalidNetworkHandle;
+  for (NetworkChangeNotifier::NetworkHandle n : network_list) {
+    if (n != network) {
+      new_network = n;
+      break;
+    }
+  }
+
+  QuicStreamFactory::SessionIdMap::iterator it = all_sessions_.begin();
+  while (it != all_sessions_.end()) {
+    QuicChromiumClientSession* session = it->first;
+    QuicServerId server_id = it->second;
+    ++it;
+
+    if (session->GetDefaultSocket()->GetBoundNetwork() != network) {

[Ryan Hamilton, 2015/12/29 05:29:36]

It looks like this is the only non-private caller of GetDefaultSocket(). If so,
the Law of Demeter would suggest that instead of GetDefaultSocket, the session
should expose IsBoundToNetwork() (or perhaps something about Current or
Default). Admittedly this is not the most important thing in the world, but
still :>

https://en.wikipedia.org/wiki/Law_of_Demeter
"That is, the code a.b.Method() breaks the law where a.Method() does not."

[Jana, 2016/01/06 23:01:17]

Noted. GetDefaultSocket() is used directly elsewhere now in the session, so
leaving it as is.

+      // If session is not bound to |network|, move on.
+      HistogramMigrationStatus(MIGRATION_STATUS_ALREADY_MIGRATED);
+      continue;
+    }
+    if (session->GetNumActiveStreams() == 0) {
+      // Close idle sessions.
+      session->CloseSessionOnError(
+          ERR_NETWORK_CHANGED, QUIC_CONNECTION_MIGRATION_NO_MIGRATABLE_STREAMS);
+      HistogramMigrationStatus(MIGRATION_STATUS_NO_MIGRATABLE_STREAMS);
+      continue;
+    }
+    // If session has active streams, mark it as going away.
+    OnSessionGoingAway(session);
+    if (new_network == NetworkChangeNotifier::kInvalidNetworkHandle) {
+      // No new network was found.
+      if (force_close) {
+        session->CloseSessionOnError(ERR_NETWORK_CHANGED,
+                                     QUIC_CONNECTION_MIGRATION_NO_NEW_NETWORK);
+      }
+      continue;
+    }
+
+    // Use OS-specified port for socket (DEFAULT_BIND) instead of
+    // using the PortSuggester since the connection is being migrated
+    // and not being newly created.
+    scoped_ptr<DatagramClientSocket> socket(
+        client_socket_factory_->CreateDatagramClientSocket(
+            DatagramSocket::DEFAULT_BIND, RandIntCallback(),
+            session->net_log().net_log(), session->net_log().source()));
+
+    QuicConnection* connection = session->connection();
+    if (ConfigureDatagramClientSocket(socket.get(), connection->peer_address(),
+                                      new_network) != OK) {
+      session->CloseSessionOnError(ERR_NETWORK_CHANGED, QUIC_INTERNAL_ERROR);
+      HistogramMigrationStatus(MIGRATION_STATUS_INTERNAL_ERROR);
+      continue;
+    }
+
+    scoped_ptr<QuicPacketReader> new_reader(new QuicPacketReader(
+        socket.get(), clock_.get(), session, yield_after_packets_,
+        yield_after_duration_, session->net_log()));
+    DefaultPacketWriterFactory packet_writer_factory(socket.get());
+    scoped_ptr<QuicPacketWriter> new_writer(
+        packet_writer_factory.Create(connection));
+
+    if (!session->MigrateToSocket(std::move(socket), std::move(new_reader),
+                                  std::move(new_writer))) {
+      session->CloseSessionOnError(ERR_NETWORK_CHANGED,
+                                   QUIC_CONNECTION_MIGRATION_TOO_MANY_CHANGES);
+      HistogramMigrationStatus(MIGRATION_STATUS_TOO_MANY_CHANGES);
+    } else {
+      HistogramMigrationStatus(MIGRATION_STATUS_SUCCESS);
+    }
+  }
+}
+
 void QuicStreamFactory::OnSSLConfigChanged() {
-  CloseAllSessions(ERR_CERT_DATABASE_CHANGED);
+  CloseAllSessions(ERR_CERT_DATABASE_CHANGED, QUIC_INTERNAL_ERROR);
 }
 
 void QuicStreamFactory::OnCertAdded(const X509Certificate* cert) {
-  CloseAllSessions(ERR_CERT_DATABASE_CHANGED);
+  CloseAllSessions(ERR_CERT_DATABASE_CHANGED, QUIC_INTERNAL_ERROR);
 }
 
 void QuicStreamFactory::OnCACertChanged(const X509Certificate* cert) {
@@ -1164,7 +1283,7 @@ void QuicStreamFactory::OnCACertChanged(const X509Certificate* cert) {
   // Since the OnCACertChanged method doesn't tell us what
   // kind of change it is, we have to flush the socket
   // pools to be safe.
-  CloseAllSessions(ERR_CERT_DATABASE_CHANGED);
+  CloseAllSessions(ERR_CERT_DATABASE_CHANGED, QUIC_INTERNAL_ERROR);
 }
 
 bool QuicStreamFactory::HasActiveSession(const QuicServerId& server_id) const {
@@ -1178,35 +1297,10 @@ bool QuicStreamFactory::HasActiveJob(const QuicServerId& key) const {
   return ContainsKey(active_jobs_, key);
 }
 
-int QuicStreamFactory::CreateSession(const QuicServerId& server_id,
-                                     int cert_verify_flags,
-                                     scoped_ptr<QuicServerInfo> server_info,
-                                     const AddressList& address_list,
-                                     base::TimeTicks dns_resolution_end_time,
-                                     const BoundNetLog& net_log,
-                                     QuicChromiumClientSession** session) {
-  bool enable_port_selection = enable_port_selection_;
-  if (enable_port_selection && ContainsKey(gone_away_aliases_, server_id)) {
-    // Disable port selection when the server is going away.
-    // There is no point in trying to return to the same server, if
-    // that server is no longer handling requests.
-    enable_port_selection = false;
-    gone_away_aliases_.erase(server_id);
-  }
-
-  QuicConnectionId connection_id = random_generator_->RandUint64();
-  IPEndPoint addr = *address_list.begin();
-  scoped_refptr<PortSuggester> port_suggester =
-      new PortSuggester(server_id.host_port_pair(), port_seed_);
-  DatagramSocket::BindType bind_type =
-      enable_port_selection ? DatagramSocket::RANDOM_BIND
-                            :            // Use our callback.
-          DatagramSocket::DEFAULT_BIND;  // Use OS to randomize.
-  scoped_ptr<DatagramClientSocket> socket(
-      client_socket_factory_->CreateDatagramClientSocket(
-          bind_type, base::Bind(&PortSuggester::SuggestPort, port_suggester),
-          net_log.net_log(), net_log.source()));
-
+int QuicStreamFactory::ConfigureDatagramClientSocket(
+    DatagramClientSocket* socket,
+    IPEndPoint addr,
+    NetworkChangeNotifier::NetworkHandle network) {
   if (enable_non_blocking_io_ &&
       client_socket_factory_ == ClientSocketFactory::GetDefaultFactory()) {
 #if defined(OS_WIN)
@@ -1214,25 +1308,30 @@ int QuicStreamFactory::CreateSession(const QuicServerId& server_id,
 #endif
   }
 
-  int rv = socket->Connect(addr);
+  // If caller leaves network unspecified, use current default.
+  int rv;
+  if (migrate_sessions_on_network_change_) {
+    if (network == NetworkChangeNotifier::kInvalidNetworkHandle) {
+      rv = socket->BindToDefaultNetwork();
+    } else {
+      rv = socket->BindToNetwork(network);
+    }
+    if (rv != OK)
+      return rv;
+  }
 
+  rv = socket->Connect(addr);
   if (rv != OK) {
     HistogramCreateSessionFailure(CREATION_ERROR_CONNECTING_SOCKET);
     return rv;
   }
-  UMA_HISTOGRAM_COUNTS("Net.QuicEphemeralPortsSuggested",
-                       port_suggester->call_count());
-  if (enable_port_selection) {
-    DCHECK_LE(1u, port_suggester->call_count());
-  } else {
-    DCHECK_EQ(0u, port_suggester->call_count());
-  }
 
   rv = socket->SetReceiveBufferSize(socket_receive_buffer_size_);
   if (rv != OK) {
     HistogramCreateSessionFailure(CREATION_ERROR_SETTING_RECEIVE_BUFFER);
     return rv;
   }
+
   // Set a buffer large enough to contain the initial CWND's worth of packet
   // to work around the problem with CHLO packets being sent out with the
   // wrong encryption level, when the send buffer is full.
@@ -1252,14 +1351,60 @@ int QuicStreamFactory::CreateSession(const QuicServerId& server_id,
     }
   }
 
-  DefaultPacketWriterFactory packet_writer_factory(socket.get());
+  return OK;
+}
 
+int QuicStreamFactory::CreateSession(const QuicServerId& server_id,
+                                     int cert_verify_flags,
+                                     scoped_ptr<QuicServerInfo> server_info,
+                                     const AddressList& address_list,
+                                     base::TimeTicks dns_resolution_end_time,
+                                     const BoundNetLog& net_log,
+                                     QuicChromiumClientSession** session) {
+  IPEndPoint addr = *address_list.begin();
+  bool enable_port_selection = enable_port_selection_;
+  if (enable_port_selection && ContainsKey(gone_away_aliases_, server_id)) {
+    // Disable port selection when the server is going away.
+    // There is no point in trying to return to the same server, if
+    // that server is no longer handling requests.
+    enable_port_selection = false;
+    gone_away_aliases_.erase(server_id);
+  }
+  scoped_refptr<PortSuggester> port_suggester =
+      new PortSuggester(server_id.host_port_pair(), port_seed_);
+  DatagramSocket::BindType bind_type =
+      enable_port_selection ? DatagramSocket::RANDOM_BIND
+                            :            // Use our callback.
+          DatagramSocket::DEFAULT_BIND;  // Use OS to randomize.
+
+  scoped_ptr<DatagramClientSocket> socket(
+      client_socket_factory_->CreateDatagramClientSocket(
+          bind_type, base::Bind(&PortSuggester::SuggestPort, port_suggester),
+          net_log.net_log(), net_log.source()));
+
+  // Passing in kInvalidNetworkHandle binds socket to default network.
+  int rv = ConfigureDatagramClientSocket(
+      socket.get(), addr, NetworkChangeNotifier::kInvalidNetworkHandle);
+  if (rv != OK) {
+    return rv;
+  }
+
+  UMA_HISTOGRAM_COUNTS("Net.QuicEphemeralPortsSuggested",
+                       port_suggester->call_count());
+  if (enable_port_selection) {
+    DCHECK_LE(1u, port_suggester->call_count());
+  } else {
+    DCHECK_EQ(0u, port_suggester->call_count());
+  }
+
+  DefaultPacketWriterFactory packet_writer_factory(socket.get());
   if (!helper_.get()) {
     helper_.reset(
         new QuicConnectionHelper(base::ThreadTaskRunnerHandle::Get().get(),
                                  clock_.get(), random_generator_));
   }
 
+  QuicConnectionId connection_id = random_generator_->RandUint64();
   QuicConnection* connection = new QuicConnection(
       connection_id, addr, helper_.get(), packet_writer_factory,
       true /* owns_writer */, Perspective::IS_CLIENT, supported_versions_);