Add an active ICE controller that wraps a legacy controller (#7/n)

The wrapping ICE controller will allow existing ICE controller implementations to migrate to the active interface, and eventually deprecate the legacy interface.

Follow-up CL has unit tests for P2PTransportChannel using the new wrapping controller.

Bug: webrtc:14367, webrtc:14131
Change-Id: I6c517449ff1e503e8268a7ef91afda793723fdeb
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/275302
Reviewed-by: Per Kjellander <perkj@webrtc.org>
Reviewed-by: Jonas Oreland <jonaso@webrtc.org>
Commit-Queue: Sameer Vijaykar <samvi@google.com>
Cr-Commit-Position: refs/heads/main@{#38130}

api/ice_transport_interface.h

@@ -99,8 +99,10 @@ struct IceTransportInit final {
   //      constructed and used.
   //
   //   2. If the field trial is enabled
-  //      - then an active ICE controller factory must be supplied and is used.
-  //      - the legacy ICE controller factory is not used in this case.
+  //      a. If an active ICE controller factory is supplied, it is used and
+  //      the legacy ICE controller factory is not used.
+  //      b. If not, a default active ICE controller is used, wrapping over the
+  //      supplied or the default legacy ICE controller.
   void set_active_ice_controller_factory(
       cricket::ActiveIceControllerFactoryInterface*
           active_ice_controller_factory) {

p2p/BUILD.gn

@@ -81,6 +81,8 @@ rtc_library("rtc_p2p") {
     "base/turn_port.cc",
     "base/turn_port.h",
     "base/udp_port.h",
+    "base/wrapping_active_ice_controller.cc",
+    "base/wrapping_active_ice_controller.h",
     "client/basic_port_allocator.cc",
     "client/basic_port_allocator.h",
     "client/relay_port_factory_interface.h",
@@ -201,6 +203,7 @@ if (rtc_include_tests) {
       "base/fake_packet_transport.h",
       "base/mock_active_ice_controller.h",
       "base/mock_async_resolver.h",
+      "base/mock_ice_agent.h",
       "base/mock_ice_controller.h",
       "base/mock_ice_transport.h",
       "base/test_stun_server.cc",
@@ -260,6 +263,7 @@ if (rtc_include_tests) {
       "base/transport_description_unittest.cc",
       "base/turn_port_unittest.cc",
       "base/turn_server_unittest.cc",
+      "base/wrapping_active_ice_controller_unittest.cc",
       "client/basic_port_allocator_unittest.cc",
     ]
     deps = [

p2p/base/mock_ice_agent.h

@@ -0,0 +1,50 @@
+/*
+ *  Copyright 2018 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef P2P_BASE_MOCK_ICE_AGENT_H_
+#define P2P_BASE_MOCK_ICE_AGENT_H_
+
+#include <vector>
+
+#include "p2p/base/connection.h"
+#include "p2p/base/ice_agent_interface.h"
+#include "p2p/base/ice_switch_reason.h"
+#include "p2p/base/transport_description.h"
+#include "test/gmock.h"
+
+namespace cricket {
+
+class MockIceAgent : public IceAgentInterface {
+ public:
+  ~MockIceAgent() override = default;
+
+  MOCK_METHOD(int64_t, GetLastPingSentMs, (), (override, const));
+  MOCK_METHOD(IceRole, GetIceRole, (), (override, const));
+  MOCK_METHOD(void, OnStartedPinging, (), (override));
+  MOCK_METHOD(void, UpdateConnectionStates, (), (override));
+  MOCK_METHOD(void, UpdateState, (), (override));
+  MOCK_METHOD(void,
+              ForgetLearnedStateForConnections,
+              (std::vector<const Connection*>),
+              (override));
+  MOCK_METHOD(void, SendPingRequest, (const Connection*), (override));
+  MOCK_METHOD(void,
+              SwitchSelectedConnection,
+              (const Connection*, IceSwitchReason),
+              (override));
+  MOCK_METHOD(bool,
+              PruneConnections,
+              (std::vector<const Connection*>),
+              (override));
+};
+
+}  // namespace cricket
+
+#endif  // P2P_BASE_MOCK_ICE_AGENT_H_

p2p/base/p2p_transport_channel.cc

@@ -33,6 +33,7 @@
 #include "p2p/base/connection.h"
 #include "p2p/base/connection_info.h"
 #include "p2p/base/port.h"
+#include "p2p/base/wrapping_active_ice_controller.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/crc32.h"
 #include "rtc_base/experiments/struct_parameters_parser.h"
@@ -2472,10 +2473,15 @@ P2PTransportChannel::IceControllerAdapter::IceControllerAdapter(
     P2PTransportChannel* transport)
     : transport_(transport) {
   if (UseActiveIceControllerFieldTrialEnabled(field_trials)) {
-    RTC_DCHECK(active_ice_controller_factory);
-    ActiveIceControllerFactoryArgs active_args{args,
-                                               /* ice_agent= */ transport};
-    active_ice_controller_ = active_ice_controller_factory->Create(active_args);
+    if (active_ice_controller_factory) {
+      ActiveIceControllerFactoryArgs active_args{args,
+                                                 /* ice_agent= */ transport};
+      active_ice_controller_ =
+          active_ice_controller_factory->Create(active_args);
+    } else {
+      active_ice_controller_ = std::make_unique<WrappingActiveIceController>(
+          /* ice_agent= */ transport, ice_controller_factory, args);
+    }
   } else {
     if (ice_controller_factory != nullptr) {
       legacy_ice_controller_ = ice_controller_factory->Create(args);

p2p/base/wrapping_active_ice_controller.cc

@@ -0,0 +1,253 @@
+/*
+ *  Copyright 2022 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "p2p/base/wrapping_active_ice_controller.h"
+
+#include <memory>
+#include <utility>
+#include <vector>
+
+#include "api/sequence_checker.h"
+#include "api/task_queue/pending_task_safety_flag.h"
+#include "api/units/time_delta.h"
+#include "p2p/base/basic_ice_controller.h"
+#include "p2p/base/connection.h"
+#include "p2p/base/ice_agent_interface.h"
+#include "p2p/base/ice_controller_interface.h"
+#include "p2p/base/ice_switch_reason.h"
+#include "p2p/base/ice_transport_internal.h"
+#include "p2p/base/transport_description.h"
+#include "rtc_base/logging.h"
+#include "rtc_base/thread.h"
+#include "rtc_base/time_utils.h"
+
+namespace {
+using ::webrtc::SafeTask;
+using ::webrtc::TimeDelta;
+}  // unnamed namespace
+
+namespace cricket {
+
+WrappingActiveIceController::WrappingActiveIceController(
+    IceAgentInterface* ice_agent,
+    std::unique_ptr<IceControllerInterface> wrapped)
+    : network_thread_(rtc::Thread::Current()),
+      wrapped_(std::move(wrapped)),
+      agent_(*ice_agent) {
+  RTC_DCHECK(ice_agent != nullptr);
+}
+
+WrappingActiveIceController::WrappingActiveIceController(
+    IceAgentInterface* ice_agent,
+    IceControllerFactoryInterface* wrapped_factory,
+    const IceControllerFactoryArgs& wrapped_factory_args)
+    : network_thread_(rtc::Thread::Current()), agent_(*ice_agent) {
+  RTC_DCHECK(ice_agent != nullptr);
+  if (wrapped_factory) {
+    wrapped_ = wrapped_factory->Create(wrapped_factory_args);
+  } else {
+    wrapped_ = std::make_unique<BasicIceController>(wrapped_factory_args);
+  }
+}
+
+WrappingActiveIceController::~WrappingActiveIceController() {}
+
+void WrappingActiveIceController::SetIceConfig(const IceConfig& config) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  wrapped_->SetIceConfig(config);
+}
+
+bool WrappingActiveIceController::GetUseCandidateAttribute(
+    const Connection* connection,
+    NominationMode mode,
+    IceMode remote_ice_mode) const {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  return wrapped_->GetUseCandidateAttr(connection, mode, remote_ice_mode);
+}
+
+void WrappingActiveIceController::OnConnectionAdded(
+    const Connection* connection) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  wrapped_->AddConnection(connection);
+}
+
+void WrappingActiveIceController::OnConnectionPinged(
+    const Connection* connection) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  wrapped_->MarkConnectionPinged(connection);
+}
+
+void WrappingActiveIceController::OnConnectionUpdated(
+    const Connection* connection) {
+  RTC_LOG(LS_VERBOSE) << "Connection report for " << connection->ToString();
+  // Do nothing. Native ICE controllers have direct access to Connection, so no
+  // need to update connection state separately.
+}
+
+void WrappingActiveIceController::OnConnectionSwitched(
+    const Connection* connection) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  selected_connection_ = connection;
+  wrapped_->SetSelectedConnection(connection);
+}
+
+void WrappingActiveIceController::OnConnectionDestroyed(
+    const Connection* connection) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  wrapped_->OnConnectionDestroyed(connection);
+}
+
+void WrappingActiveIceController::MaybeStartPinging() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (started_pinging_) {
+    return;
+  }
+
+  if (wrapped_->HasPingableConnection()) {
+    network_thread_->PostTask(
+        SafeTask(task_safety_.flag(), [this]() { SelectAndPingConnection(); }));
+    agent_.OnStartedPinging();
+    started_pinging_ = true;
+  }
+}
+
+void WrappingActiveIceController::SelectAndPingConnection() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  agent_.UpdateConnectionStates();
+
+  IceControllerInterface::PingResult result =
+      wrapped_->SelectConnectionToPing(agent_.GetLastPingSentMs());
+  HandlePingResult(result);
+}
+
+void WrappingActiveIceController::HandlePingResult(
+    IceControllerInterface::PingResult result) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+
+  if (result.connection.has_value()) {
+    agent_.SendPingRequest(result.connection.value());
+  }
+
+  network_thread_->PostDelayedTask(
+      SafeTask(task_safety_.flag(), [this]() { SelectAndPingConnection(); }),
+      TimeDelta::Millis(result.recheck_delay_ms));
+}
+
+void WrappingActiveIceController::OnSortAndSwitchRequest(
+    IceSwitchReason reason) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (!sort_pending_) {
+    network_thread_->PostTask(SafeTask(task_safety_.flag(), [this, reason]() {
+      SortAndSwitchToBestConnection(reason);
+    }));
+    sort_pending_ = true;
+  }
+}
+
+void WrappingActiveIceController::OnImmediateSortAndSwitchRequest(
+    IceSwitchReason reason) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  SortAndSwitchToBestConnection(reason);
+}
+
+void WrappingActiveIceController::SortAndSwitchToBestConnection(
+    IceSwitchReason reason) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+
+  // Make sure the connection states are up-to-date since this affects how they
+  // will be sorted.
+  agent_.UpdateConnectionStates();
+
+  // Any changes after this point will require a re-sort.
+  sort_pending_ = false;
+
+  IceControllerInterface::SwitchResult result =
+      wrapped_->SortAndSwitchConnection(reason);
+  HandleSwitchResult(reason, result);
+  UpdateStateOnConnectionsResorted();
+}
+
+bool WrappingActiveIceController::OnImmediateSwitchRequest(
+    IceSwitchReason reason,
+    const Connection* selected) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  IceControllerInterface::SwitchResult result =
+      wrapped_->ShouldSwitchConnection(reason, selected);
+  HandleSwitchResult(reason, result);
+  return result.connection.has_value();
+}
+
+void WrappingActiveIceController::HandleSwitchResult(
+    IceSwitchReason reason_for_switch,
+    IceControllerInterface::SwitchResult result) {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  if (result.connection.has_value()) {
+    RTC_LOG(LS_INFO) << "Switching selected connection due to: "
+                     << IceSwitchReasonToString(reason_for_switch);
+    agent_.SwitchSelectedConnection(result.connection.value(),
+                                    reason_for_switch);
+  }
+
+  if (result.recheck_event.has_value()) {
+    // If we do not switch to the connection because it missed the receiving
+    // threshold, the new connection is in a better receiving state than the
+    // currently selected connection. So we need to re-check whether it needs
+    // to be switched at a later time.
+    network_thread_->PostDelayedTask(
+        SafeTask(task_safety_.flag(),
+                 [this, recheck_reason = result.recheck_event->reason]() {
+                   SortAndSwitchToBestConnection(recheck_reason);
+                 }),
+        TimeDelta::Millis(result.recheck_event->recheck_delay_ms));
+  }
+
+  agent_.ForgetLearnedStateForConnections(
+      result.connections_to_forget_state_on);
+}
+
+void WrappingActiveIceController::UpdateStateOnConnectionsResorted() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  PruneConnections();
+
+  // Update the internal state of the ICE agentl.
+  agent_.UpdateState();
+
+  // Also possibly start pinging.
+  // We could start pinging if:
+  // * The first connection was created.
+  // * ICE credentials were provided.
+  // * A TCP connection became connected.
+  MaybeStartPinging();
+}
+
+void WrappingActiveIceController::PruneConnections() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+
+  // The controlled side can prune only if the selected connection has been
+  // nominated because otherwise it may prune the connection that will be
+  // selected by the controlling side.
+  // TODO(honghaiz): This is not enough to prevent a connection from being
+  // pruned too early because with aggressive nomination, the controlling side
+  // will nominate every connection until it becomes writable.
+  if (agent_.GetIceRole() == ICEROLE_CONTROLLING ||
+      (selected_connection_ && selected_connection_->nominated())) {
+    std::vector<const Connection*> connections_to_prune =
+        wrapped_->PruneConnections();
+    agent_.PruneConnections(connections_to_prune);
+  }
+}
+
+// Only for unit tests
+const Connection* WrappingActiveIceController::FindNextPingableConnection() {
+  RTC_DCHECK_RUN_ON(network_thread_);
+  return wrapped_->FindNextPingableConnection();
+}
+
+}  // namespace cricket