Reland "Use the new DNS resolver API in PeerConnection"

This reverts commit 5a40b37105.

Reason for revert: Fixed the bug and ran layout tests.

Original change's description:
> Revert "Use the new DNS resolver API in PeerConnection"
>
> This reverts commit acf8ccb3c9.
>
> Reason for revert: Speculative revert for https://ci.chromium.org/ui/p/chromium/builders/try/win10_chromium_x64_rel_ng/b8851745102358680592/overview.
>
> Original change's description:
> > Use the new DNS resolver API in PeerConnection
> >
> > Bug: webrtc:12598
> > Change-Id: I5a14058e7f28c993ed927749df7357c715ba83fb
> > Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/212961
> > Reviewed-by: Niels Moller <nisse@webrtc.org>
> > Commit-Queue: Harald Alvestrand <hta@webrtc.org>
> > Cr-Commit-Position: refs/heads/master@{#33561}
>
> # Not skipping CQ checks because original CL landed > 1 day ago.
>
> TBR=hta@webrtc.org
>
> Bug: webrtc:12598
> Change-Id: Idc9853cb569849c49052f9cbd865614710fff979
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/213188
> Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#33591}

# Not skipping CQ checks because original CL landed > 1 day ago.

Bug: webrtc:12598
Change-Id: Ief7867f2f23de66504877cdab1b23a11df2d5de4
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/214120
Commit-Queue: Harald Alvestrand <hta@webrtc.org>
Reviewed-by: Tommi <tommi@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#33647}

api/BUILD.gn

@@ -160,6 +160,7 @@ rtc_library("libjingle_peerconnection_api") {
   ]
   deps = [
     ":array_view",
+    ":async_dns_resolver",
     ":audio_options_api",
     ":callfactory_api",
     ":fec_controller_api",
@@ -249,11 +250,11 @@ rtc_library("rtc_error") {
 rtc_source_set("packet_socket_factory") {
   visibility = [ "*" ]
   sources = [
-    "async_dns_resolver.h",
     "async_resolver_factory.h",
     "packet_socket_factory.h",
   ]
   deps = [
+    ":async_dns_resolver",
     "../rtc_base:async_resolver_interface",
     "../rtc_base:rtc_base",
     "../rtc_base:socket_address",
@@ -261,6 +262,14 @@ rtc_source_set("packet_socket_factory") {
   ]
 }
 
+rtc_source_set("async_dns_resolver") {
+  sources = [ "async_dns_resolver.h" ]
+  deps = [
+    "../rtc_base:socket_address",
+    "../rtc_base/system:rtc_export",
+  ]
+}
+
 rtc_source_set("scoped_refptr") {
   visibility = [ "*" ]
   sources = [ "scoped_refptr.h" ]
@@ -940,6 +949,15 @@ if (rtc_include_tests) {
     ]
   }
 
+  rtc_source_set("mock_async_dns_resolver") {
+    testonly = true
+    sources = [ "test/mock_async_dns_resolver.h" ]
+    deps = [
+      ":async_dns_resolver",
+      "../test:test_support",
+    ]
+  }
+
   rtc_source_set("mock_rtp") {
     visibility = [ "*" ]
     testonly = true
@@ -1092,6 +1110,7 @@ if (rtc_include_tests) {
       ":dummy_peer_connection",
       ":fake_frame_decryptor",
       ":fake_frame_encryptor",
+      ":mock_async_dns_resolver",
       ":mock_audio_mixer",
       ":mock_data_channel",
       ":mock_frame_decryptor",

api/async_dns_resolver.h

@@ -11,6 +11,7 @@
 #ifndef API_ASYNC_DNS_RESOLVER_H_
 #define API_ASYNC_DNS_RESOLVER_H_
 
+#include <functional>
 #include <memory>
 
 #include "rtc_base/socket_address.h"

api/ice_transport_factory.cc

@@ -58,10 +58,18 @@ rtc::scoped_refptr<IceTransportInterface> CreateIceTransport(
 
 rtc::scoped_refptr<IceTransportInterface> CreateIceTransport(
     IceTransportInit init) {
+  if (init.async_resolver_factory()) {
+    // Backwards compatibility mode
     return new rtc::RefCountedObject<IceTransportWithTransportChannel>(
         std::make_unique<cricket::P2PTransportChannel>(
             "", cricket::ICE_CANDIDATE_COMPONENT_RTP, init.port_allocator(),
             init.async_resolver_factory(), init.event_log()));
+  } else {
+    return new rtc::RefCountedObject<IceTransportWithTransportChannel>(
+        cricket::P2PTransportChannel::Create(
+            "", cricket::ICE_CANDIDATE_COMPONENT_RTP, init.port_allocator(),
+            init.async_dns_resolver_factory(), init.event_log()));
+  }
 }
 
 }  // namespace webrtc

api/ice_transport_interface.h

@@ -13,6 +13,7 @@
 
 #include <string>
 
+#include "api/async_dns_resolver.h"
 #include "api/async_resolver_factory.h"
 #include "api/rtc_error.h"
 #include "api/rtc_event_log/rtc_event_log.h"
@@ -52,11 +53,21 @@ struct IceTransportInit final {
     port_allocator_ = port_allocator;
   }
 
+  AsyncDnsResolverFactoryInterface* async_dns_resolver_factory() {
+    return async_dns_resolver_factory_;
+  }
+  void set_async_dns_resolver_factory(
+      AsyncDnsResolverFactoryInterface* async_dns_resolver_factory) {
+    RTC_DCHECK(!async_resolver_factory_);
+    async_dns_resolver_factory_ = async_dns_resolver_factory;
+  }
   AsyncResolverFactory* async_resolver_factory() {
     return async_resolver_factory_;
   }
+  ABSL_DEPRECATED("bugs.webrtc.org/12598")
   void set_async_resolver_factory(
       AsyncResolverFactory* async_resolver_factory) {
+    RTC_DCHECK(!async_dns_resolver_factory_);
     async_resolver_factory_ = async_resolver_factory;
   }
 
@@ -65,8 +76,11 @@ struct IceTransportInit final {
 
  private:
   cricket::PortAllocator* port_allocator_ = nullptr;
+  AsyncDnsResolverFactoryInterface* async_dns_resolver_factory_ = nullptr;
+  // For backwards compatibility. Only one resolver factory can be set.
   AsyncResolverFactory* async_resolver_factory_ = nullptr;
   RtcEventLog* event_log_ = nullptr;
+  // TODO(https://crbug.com/webrtc/12657): Redesign to have const members.
 };
 
 // TODO(qingsi): The factory interface is defined in this file instead of its

api/peer_connection_interface.h

@@ -74,6 +74,7 @@
 #include <vector>
 
 #include "api/adaptation/resource.h"
+#include "api/async_dns_resolver.h"
 #include "api/async_resolver_factory.h"
 #include "api/audio/audio_mixer.h"
 #include "api/audio_codecs/audio_decoder_factory.h"
@@ -1322,6 +1323,10 @@ struct RTC_EXPORT PeerConnectionDependencies final {
   // packet_socket_factory, not both.
   std::unique_ptr<cricket::PortAllocator> allocator;
   std::unique_ptr<rtc::PacketSocketFactory> packet_socket_factory;
+  // Factory for creating resolvers that look up hostnames in DNS
+  std::unique_ptr<webrtc::AsyncDnsResolverFactoryInterface>
+      async_dns_resolver_factory;
+  // Deprecated - use async_dns_resolver_factory
   std::unique_ptr<webrtc::AsyncResolverFactory> async_resolver_factory;
   std::unique_ptr<webrtc::IceTransportFactory> ice_transport_factory;
   std::unique_ptr<rtc::RTCCertificateGeneratorInterface> cert_generator;

api/test/compile_all_headers.cc

@@ -30,6 +30,7 @@
 #include "api/test/dummy_peer_connection.h"
 #include "api/test/fake_frame_decryptor.h"
 #include "api/test/fake_frame_encryptor.h"
+#include "api/test/mock_async_dns_resolver.h"
 #include "api/test/mock_audio_mixer.h"
 #include "api/test/mock_data_channel.h"
 #include "api/test/mock_frame_decryptor.h"

api/test/mock_async_dns_resolver.h

@@ -0,0 +1,54 @@
+/*
+ *  Copyright 2021 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 API_TEST_MOCK_ASYNC_DNS_RESOLVER_H_
+#define API_TEST_MOCK_ASYNC_DNS_RESOLVER_H_
+
+#include <functional>
+#include <memory>
+
+#include "api/async_dns_resolver.h"
+#include "test/gmock.h"
+
+namespace webrtc {
+
+class MockAsyncDnsResolverResult : public AsyncDnsResolverResult {
+ public:
+  MOCK_METHOD(bool,
+              GetResolvedAddress,
+              (int, rtc::SocketAddress*),
+              (const override));
+  MOCK_METHOD(int, GetError, (), (const override));
+};
+
+class MockAsyncDnsResolver : public AsyncDnsResolverInterface {
+ public:
+  MOCK_METHOD(void,
+              Start,
+              (const rtc::SocketAddress&, std::function<void()>),
+              (override));
+  MOCK_METHOD(AsyncDnsResolverResult&, result, (), (const override));
+};
+
+class MockAsyncDnsResolverFactory : public AsyncDnsResolverFactoryInterface {
+ public:
+  MOCK_METHOD(std::unique_ptr<webrtc::AsyncDnsResolverInterface>,
+              CreateAndResolve,
+              (const rtc::SocketAddress&, std::function<void()>),
+              (override));
+  MOCK_METHOD(std::unique_ptr<webrtc::AsyncDnsResolverInterface>,
+              Create,
+              (),
+              (override));
+};
+
+}  // namespace webrtc
+
+#endif  // API_TEST_MOCK_ASYNC_DNS_RESOLVER_H_

p2p/BUILD.gn

@@ -86,6 +86,8 @@ rtc_library("rtc_p2p") {
   ]
 
   deps = [
+    "../api:array_view",
+    "../api:async_dns_resolver",
     "../api:libjingle_peerconnection_api",
     "../api:packet_socket_factory",
     "../api:rtc_error",
@@ -93,6 +95,7 @@ rtc_library("rtc_p2p") {
     "../api:sequence_checker",
     "../api/crypto:options",
     "../api/rtc_event_log",
+    "../api/task_queue",
     "../api/transport:enums",
     "../api/transport:stun_types",
     "../logging:ice_log",
@@ -235,6 +238,7 @@ if (rtc_include_tests) {
       ":p2p_test_utils",
       ":rtc_p2p",
       "../api:libjingle_peerconnection_api",
+      "../api:mock_async_dns_resolver",
       "../api:packet_socket_factory",
       "../api:scoped_refptr",
       "../api/transport:stun_types",
@@ -256,6 +260,7 @@ if (rtc_include_tests) {
       "../rtc_base/third_party/sigslot",
       "../system_wrappers:metrics",
       "../test:field_trial",
+      "../test:rtc_expect_death",
       "../test:test_support",
       "//testing/gtest",
     ]

p2p/base/basic_async_resolver_factory.cc

@@ -16,6 +16,7 @@
 #include "absl/memory/memory.h"
 #include "api/async_dns_resolver.h"
 #include "rtc_base/async_resolver.h"
+#include "rtc_base/logging.h"
 
 namespace webrtc {
 
@@ -46,11 +47,19 @@ class WrappingAsyncDnsResolver : public AsyncDnsResolverInterface,
   explicit WrappingAsyncDnsResolver(rtc::AsyncResolverInterface* wrapped)
       : wrapped_(absl::WrapUnique(wrapped)), result_(this) {}
 
-  ~WrappingAsyncDnsResolver() override { wrapped_.release()->Destroy(false); }
+  ~WrappingAsyncDnsResolver() override {
+    // Workaround to get around the fact that sigslot-using objects can't be
+    // destroyed from within their callback: Alert class users early.
+    // TODO(bugs.webrtc.org/12651): Delete this class once the sigslot users are
+    // gone.
+    RTC_CHECK(!within_resolve_result_);
+    wrapped_.release()->Destroy(false);
+  }
 
   void Start(const rtc::SocketAddress& addr,
              std::function<void()> callback) override {
-    RTC_DCHECK(state_ == State::kNotStarted);
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
+    RTC_DCHECK_EQ(State::kNotStarted, state_);
     state_ = State::kStarted;
     callback_ = callback;
     wrapped_->SignalDone.connect(this,
@@ -59,27 +68,39 @@ class WrappingAsyncDnsResolver : public AsyncDnsResolverInterface,
   }
 
   const AsyncDnsResolverResult& result() const override {
-    RTC_DCHECK(state_ == State::kResolved);
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
+    RTC_DCHECK_EQ(State::kResolved, state_);
     return result_;
   }
 
-  // For use by WrappingAsyncDnsResolverResult
-  rtc::AsyncResolverInterface* wrapped() const { return wrapped_.get(); }
-
  private:
   enum class State { kNotStarted, kStarted, kResolved };
 
+  friend class WrappingAsyncDnsResolverResult;
+  // For use by WrappingAsyncDnsResolverResult
+  rtc::AsyncResolverInterface* wrapped() const {
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
+    return wrapped_.get();
+  }
+
   void OnResolveResult(rtc::AsyncResolverInterface* ref) {
+    RTC_DCHECK_RUN_ON(&sequence_checker_);
     RTC_DCHECK(state_ == State::kStarted);
     RTC_DCHECK_EQ(ref, wrapped_.get());
     state_ = State::kResolved;
+    within_resolve_result_ = true;
     callback_();
+    within_resolve_result_ = false;
   }
 
-  std::function<void()> callback_;
+  // The class variables need to be accessed on a single thread.
-  std::unique_ptr<rtc::AsyncResolverInterface> wrapped_;
+  SequenceChecker sequence_checker_;
-  State state_ = State::kNotStarted;
+  std::function<void()> callback_ RTC_GUARDED_BY(sequence_checker_);
-  WrappingAsyncDnsResolverResult result_;
+  std::unique_ptr<rtc::AsyncResolverInterface> wrapped_
+      RTC_GUARDED_BY(sequence_checker_);
+  State state_ RTC_GUARDED_BY(sequence_checker_) = State::kNotStarted;
+  WrappingAsyncDnsResolverResult result_ RTC_GUARDED_BY(sequence_checker_);
+  bool within_resolve_result_ RTC_GUARDED_BY(sequence_checker_) = false;
 };
 
 bool WrappingAsyncDnsResolverResult::GetResolvedAddress(

p2p/base/basic_async_resolver_factory.h

@@ -32,9 +32,15 @@ class BasicAsyncResolverFactory final : public AsyncResolverFactory {
 class WrappingAsyncDnsResolverFactory final
     : public AsyncDnsResolverFactoryInterface {
  public:
-  WrappingAsyncDnsResolverFactory(
+  explicit WrappingAsyncDnsResolverFactory(
       std::unique_ptr<AsyncResolverFactory> wrapped_factory)
-      : wrapped_factory_(std::move(wrapped_factory)) {}
+      : owned_factory_(std::move(wrapped_factory)),
+        wrapped_factory_(owned_factory_.get()) {}
+
+  explicit WrappingAsyncDnsResolverFactory(
+      AsyncResolverFactory* non_owned_factory)
+      : wrapped_factory_(non_owned_factory) {}
+
   std::unique_ptr<webrtc::AsyncDnsResolverInterface> CreateAndResolve(
       const rtc::SocketAddress& addr,
       std::function<void()> callback) override;
@@ -42,7 +48,8 @@ class WrappingAsyncDnsResolverFactory final
   std::unique_ptr<webrtc::AsyncDnsResolverInterface> Create() override;
 
  private:
-  const std::unique_ptr<AsyncResolverFactory> wrapped_factory_;
+  const std::unique_ptr<AsyncResolverFactory> owned_factory_;
+  AsyncResolverFactory* const wrapped_factory_;
 };
 
 }  // namespace webrtc

p2p/base/basic_async_resolver_factory_unittest.cc

@@ -10,10 +10,15 @@
 
 #include "p2p/base/basic_async_resolver_factory.h"
 
+#include "api/test/mock_async_dns_resolver.h"
+#include "p2p/base/mock_async_resolver.h"
+#include "rtc_base/async_resolver.h"
 #include "rtc_base/gunit.h"
 #include "rtc_base/socket_address.h"
 #include "rtc_base/third_party/sigslot/sigslot.h"
+#include "test/gmock.h"
 #include "test/gtest.h"
+#include "test/testsupport/rtc_expect_death.h"
 
 namespace webrtc {
 
@@ -47,7 +52,7 @@ TEST_F(BasicAsyncResolverFactoryTest, TestCreate) {
   TestCreate();
 }
 
-TEST(WrappingAsyncDnsResolverFactoryTest, TestCreate) {
+TEST(WrappingAsyncDnsResolverFactoryTest, TestCreateAndResolve) {
   WrappingAsyncDnsResolverFactory factory(
       std::make_unique<BasicAsyncResolverFactory>());
 
@@ -61,4 +66,24 @@ TEST(WrappingAsyncDnsResolverFactoryTest, TestCreate) {
   resolver.reset();
 }
 
+TEST(WrappingAsyncDnsResolverFactoryTest, WrapOtherResolver) {
+  BasicAsyncResolverFactory non_owned_factory;
+  WrappingAsyncDnsResolverFactory factory(&non_owned_factory);
+  std::unique_ptr<AsyncDnsResolverInterface> resolver(factory.Create());
+  ASSERT_TRUE(resolver);
+
+  bool address_resolved = false;
+  rtc::SocketAddress address("", 0);
+  resolver->Start(address, [&address_resolved]() { address_resolved = true; });
+  ASSERT_TRUE_WAIT(address_resolved, 10000 /*ms*/);
+  resolver.reset();
+}
+
+void CallResolver(WrappingAsyncDnsResolverFactory& factory) {
+  rtc::SocketAddress address("", 0);
+  std::unique_ptr<AsyncDnsResolverInterface> resolver(factory.Create());
+  resolver->Start(address, [&resolver]() { resolver.reset(); });
+  WAIT(!resolver.get(), 10000 /*ms*/);
+}
+
 }  // namespace webrtc

p2p/base/default_ice_transport_factory.cc

@@ -45,9 +45,9 @@ DefaultIceTransportFactory::CreateIceTransport(
     IceTransportInit init) {
   BasicIceControllerFactory factory;
   return new rtc::RefCountedObject<DefaultIceTransport>(
-      std::make_unique<cricket::P2PTransportChannel>(
+      cricket::P2PTransportChannel::Create(
           transport_name, component, init.port_allocator(),
-          init.async_resolver_factory(), init.event_log(), &factory));
+          init.async_dns_resolver_factory(), init.event_log(), &factory));
 }
 
 }  // namespace webrtc

p2p/base/p2p_transport_channel.cc

@@ -10,27 +10,38 @@
 
 #include "p2p/base/p2p_transport_channel.h"
 
-#include <iterator>
+#include <errno.h>
+#include <stdlib.h>
+
+#include <algorithm>
+#include <functional>
 #include <memory>
 #include <set>
 #include <utility>
 
 #include "absl/algorithm/container.h"
+#include "absl/memory/memory.h"
 #include "absl/strings/match.h"
+#include "api/async_dns_resolver.h"
 #include "api/candidate.h"
+#include "api/task_queue/queued_task.h"
 #include "logging/rtc_event_log/ice_logger.h"
+#include "p2p/base/basic_async_resolver_factory.h"
 #include "p2p/base/basic_ice_controller.h"
-#include "p2p/base/candidate_pair_interface.h"
 #include "p2p/base/connection.h"
+#include "p2p/base/connection_info.h"
 #include "p2p/base/port.h"
 #include "rtc_base/checks.h"
 #include "rtc_base/crc32.h"
 #include "rtc_base/experiments/struct_parameters_parser.h"
+#include "rtc_base/ip_address.h"
 #include "rtc_base/logging.h"
 #include "rtc_base/net_helper.h"
-#include "rtc_base/net_helpers.h"
+#include "rtc_base/network.h"
+#include "rtc_base/network_constants.h"
 #include "rtc_base/string_encode.h"
 #include "rtc_base/task_utils/to_queued_task.h"
+#include "rtc_base/third_party/sigslot/sigslot.h"
 #include "rtc_base/time_utils.h"
 #include "system_wrappers/include/field_trial.h"
 #include "system_wrappers/include/metrics.h"
@@ -122,26 +133,50 @@ bool IceCredentialsChanged(const std::string& old_ufrag,
   return (old_ufrag != new_ufrag) || (old_pwd != new_pwd);
 }
 
+// static
+std::unique_ptr<P2PTransportChannel> P2PTransportChannel::Create(
+    const std::string& transport_name,
+    int component,
+    PortAllocator* allocator,
+    webrtc::AsyncDnsResolverFactoryInterface* async_dns_resolver_factory,
+    webrtc::RtcEventLog* event_log,
+    IceControllerFactoryInterface* ice_controller_factory) {
+  return absl::WrapUnique(new P2PTransportChannel(
+      transport_name, component, allocator, async_dns_resolver_factory,
+      /* owned_dns_resolver_factory= */ nullptr, event_log,
+      ice_controller_factory));
+}
+
 P2PTransportChannel::P2PTransportChannel(const std::string& transport_name,
                                          int component,
                                          PortAllocator* allocator)
     : P2PTransportChannel(transport_name,
                           component,
                           allocator,
-                          nullptr,
+                          /* async_dns_resolver_factory= */ nullptr,
-                          nullptr) {}
+                          /* owned_dns_resolver_factory= */ nullptr,
+                          /* event_log= */ nullptr,
+                          /* ice_controller_factory= */ nullptr) {}
 
+// Private constructor, called from Create()
 P2PTransportChannel::P2PTransportChannel(
     const std::string& transport_name,
     int component,
     PortAllocator* allocator,
-    webrtc::AsyncResolverFactory* async_resolver_factory,
+    webrtc::AsyncDnsResolverFactoryInterface* async_dns_resolver_factory,
+    std::unique_ptr<webrtc::AsyncDnsResolverFactoryInterface>
+        owned_dns_resolver_factory,
     webrtc::RtcEventLog* event_log,
     IceControllerFactoryInterface* ice_controller_factory)
     : transport_name_(transport_name),
       component_(component),
       allocator_(allocator),
-      async_resolver_factory_(async_resolver_factory),
+      // If owned_dns_resolver_factory is given, async_dns_resolver_factory is
+      // ignored.
+      async_dns_resolver_factory_(owned_dns_resolver_factory
+                                      ? owned_dns_resolver_factory.get()
+                                      : async_dns_resolver_factory),
+      owned_dns_resolver_factory_(std::move(owned_dns_resolver_factory)),
       network_thread_(rtc::Thread::Current()),
       incoming_only_(false),
       error_(0),
@@ -192,15 +227,31 @@ P2PTransportChannel::P2PTransportChannel(
   }
 }
 
+// Public constructor, exposed for backwards compatibility.
+// Deprecated.
+P2PTransportChannel::P2PTransportChannel(
+    const std::string& transport_name,
+    int component,
+    PortAllocator* allocator,
+    webrtc::AsyncResolverFactory* async_resolver_factory,
+    webrtc::RtcEventLog* event_log,
+    IceControllerFactoryInterface* ice_controller_factory)
+    : P2PTransportChannel(
+          transport_name,
+          component,
+          allocator,
+          nullptr,
+          std::make_unique<webrtc::WrappingAsyncDnsResolverFactory>(
+              async_resolver_factory),
+          event_log,
+          ice_controller_factory) {}
+
 P2PTransportChannel::~P2PTransportChannel() {
   RTC_DCHECK_RUN_ON(network_thread_);
   std::vector<Connection*> copy(connections().begin(), connections().end());
   for (Connection* con : copy) {
     con->Destroy();
   }
-  for (auto& p : resolvers_) {
-    p.resolver_->Destroy(false);
-  }
   resolvers_.clear();
 }
 
@@ -1164,16 +1215,17 @@ void P2PTransportChannel::OnNominated(Connection* conn) {
 
 void P2PTransportChannel::ResolveHostnameCandidate(const Candidate& candidate) {
   RTC_DCHECK_RUN_ON(network_thread_);
-  if (!async_resolver_factory_) {
+  if (!async_dns_resolver_factory_) {
     RTC_LOG(LS_WARNING) << "Dropping ICE candidate with hostname address "
                            "(no AsyncResolverFactory)";
     return;
   }
 
-  rtc::AsyncResolverInterface* resolver = async_resolver_factory_->Create();
+  auto resolver = async_dns_resolver_factory_->Create();
-  resolvers_.emplace_back(candidate, resolver);
+  auto resptr = resolver.get();
-  resolver->SignalDone.connect(this, &P2PTransportChannel::OnCandidateResolved);
+  resolvers_.emplace_back(candidate, std::move(resolver));
-  resolver->Start(candidate.address());
+  resptr->Start(candidate.address(),
+                [this, resptr]() { OnCandidateResolved(resptr); });
   RTC_LOG(LS_INFO) << "Asynchronously resolving ICE candidate hostname "
                    << candidate.address().HostAsSensitiveURIString();
 }
@@ -1228,38 +1280,44 @@ void P2PTransportChannel::AddRemoteCandidate(const Candidate& candidate) {
 
 P2PTransportChannel::CandidateAndResolver::CandidateAndResolver(
     const Candidate& candidate,
-    rtc::AsyncResolverInterface* resolver)
+    std::unique_ptr<webrtc::AsyncDnsResolverInterface>&& resolver)
-    : candidate_(candidate), resolver_(resolver) {}
+    : candidate_(candidate), resolver_(std::move(resolver)) {}
 
 P2PTransportChannel::CandidateAndResolver::~CandidateAndResolver() {}
 
 void P2PTransportChannel::OnCandidateResolved(
-    rtc::AsyncResolverInterface* resolver) {
+    webrtc::AsyncDnsResolverInterface* resolver) {
   RTC_DCHECK_RUN_ON(network_thread_);
   auto p =
       absl::c_find_if(resolvers_, [resolver](const CandidateAndResolver& cr) {
-        return cr.resolver_ == resolver;
+        return cr.resolver_.get() == resolver;
       });
   if (p == resolvers_.end()) {
-    RTC_LOG(LS_ERROR) << "Unexpected AsyncResolver signal";
+    RTC_LOG(LS_ERROR) << "Unexpected AsyncDnsResolver return";
     RTC_NOTREACHED();
     return;
   }
   Candidate candidate = p->candidate_;
-  resolvers_.erase(p);
+  AddRemoteCandidateWithResult(candidate, resolver->result());
-  AddRemoteCandidateWithResolver(candidate, resolver);
+  // Now we can delete the resolver.
+  // TODO(bugs.webrtc.org/12651): Replace the stuff below with
+  // resolvers_.erase(p);
+  std::unique_ptr<webrtc::AsyncDnsResolverInterface> to_delete =
+      std::move(p->resolver_);
+  // Delay the actual deletion of the resolver until the lambda executes.
   network_thread_->PostTask(
-      ToQueuedTask([resolver]() { resolver->Destroy(false); }));
+      ToQueuedTask([delete_this = std::move(to_delete)] {}));
+  resolvers_.erase(p);
 }
 
-void P2PTransportChannel::AddRemoteCandidateWithResolver(
+void P2PTransportChannel::AddRemoteCandidateWithResult(
     Candidate candidate,
-    rtc::AsyncResolverInterface* resolver) {
+    const webrtc::AsyncDnsResolverResult& result) {
   RTC_DCHECK_RUN_ON(network_thread_);
-  if (resolver->GetError()) {
+  if (result.GetError()) {
     RTC_LOG(LS_WARNING) << "Failed to resolve ICE candidate hostname "
                         << candidate.address().HostAsSensitiveURIString()
-                        << " with error " << resolver->GetError();
+                        << " with error " << result.GetError();
     return;
   }
 
@@ -1267,9 +1325,8 @@ void P2PTransportChannel::AddRemoteCandidateWithResolver(
   // Prefer IPv6 to IPv4 if we have it (see RFC 5245 Section 15.1).
   // TODO(zstein): This won't work if we only have IPv4 locally but receive an
   // AAAA DNS record.
-  bool have_address =
+  bool have_address = result.GetResolvedAddress(AF_INET6, &resolved_address) ||
-      resolver->GetResolvedAddress(AF_INET6, &resolved_address) ||
+                      result.GetResolvedAddress(AF_INET, &resolved_address);
-      resolver->GetResolvedAddress(AF_INET, &resolved_address);
   if (!have_address) {
     RTC_LOG(LS_INFO) << "ICE candidate hostname "
                      << candidate.address().HostAsSensitiveURIString()

p2p/base/p2p_transport_channel.h

@@ -20,6 +20,9 @@
 #ifndef P2P_BASE_P2P_TRANSPORT_CHANNEL_H_
 #define P2P_BASE_P2P_TRANSPORT_CHANNEL_H_
 
+#include <stddef.h>
+#include <stdint.h>
+
 #include <algorithm>
 #include <map>
 #include <memory>
@@ -27,26 +30,43 @@
 #include <string>
 #include <vector>
 
+#include "absl/base/attributes.h"
+#include "absl/types/optional.h"
+#include "api/array_view.h"
+#include "api/async_dns_resolver.h"
 #include "api/async_resolver_factory.h"
 #include "api/candidate.h"
 #include "api/rtc_error.h"
+#include "api/sequence_checker.h"
+#include "api/transport/enums.h"
+#include "api/transport/stun.h"
 #include "logging/rtc_event_log/events/rtc_event_ice_candidate_pair_config.h"
 #include "logging/rtc_event_log/ice_logger.h"
 #include "p2p/base/candidate_pair_interface.h"
+#include "p2p/base/connection.h"
 #include "p2p/base/ice_controller_factory_interface.h"
 #include "p2p/base/ice_controller_interface.h"
 #include "p2p/base/ice_transport_internal.h"
 #include "p2p/base/p2p_constants.h"
 #include "p2p/base/p2p_transport_channel_ice_field_trials.h"
+#include "p2p/base/port.h"
 #include "p2p/base/port_allocator.h"
 #include "p2p/base/port_interface.h"
 #include "p2p/base/regathering_controller.h"
+#include "p2p/base/transport_description.h"
 #include "rtc_base/async_packet_socket.h"
+#include "rtc_base/checks.h"
 #include "rtc_base/constructor_magic.h"
+#include "rtc_base/dscp.h"
+#include "rtc_base/network/sent_packet.h"
+#include "rtc_base/network_route.h"
+#include "rtc_base/socket.h"
+#include "rtc_base/socket_address.h"
 #include "rtc_base/strings/string_builder.h"
 #include "rtc_base/system/rtc_export.h"
 #include "rtc_base/task_utils/pending_task_safety_flag.h"
 #include "rtc_base/third_party/sigslot/sigslot.h"
+#include "rtc_base/thread.h"
 #include "rtc_base/thread_annotations.h"
 
 namespace webrtc {
@@ -82,11 +102,19 @@ class RemoteCandidate : public Candidate {
 // two P2P clients connected to each other.
 class RTC_EXPORT P2PTransportChannel : public IceTransportInternal {
  public:
+  static std::unique_ptr<P2PTransportChannel> Create(
+      const std::string& transport_name,
+      int component,
+      PortAllocator* allocator,
+      webrtc::AsyncDnsResolverFactoryInterface* async_dns_resolver_factory,
+      webrtc::RtcEventLog* event_log = nullptr,
+      IceControllerFactoryInterface* ice_controller_factory = nullptr);
   // For testing only.
-  // TODO(zstein): Remove once AsyncResolverFactory is required.
+  // TODO(zstein): Remove once AsyncDnsResolverFactory is required.
   P2PTransportChannel(const std::string& transport_name,
                       int component,
                       PortAllocator* allocator);
+  ABSL_DEPRECATED("bugs.webrtc.org/12598")
   P2PTransportChannel(
       const std::string& transport_name,
       int component,
@@ -209,6 +237,18 @@ class RTC_EXPORT P2PTransportChannel : public IceTransportInternal {
   }
 
  private:
+  P2PTransportChannel(
+      const std::string& transport_name,
+      int component,
+      PortAllocator* allocator,
+      // DNS resolver factory
+      webrtc::AsyncDnsResolverFactoryInterface* async_dns_resolver_factory,
+      // If the P2PTransportChannel has to delete the DNS resolver factory
+      // on release, this pointer is set.
+      std::unique_ptr<webrtc::AsyncDnsResolverFactoryInterface>
+          owned_dns_resolver_factory,
+      webrtc::RtcEventLog* event_log = nullptr,
+      IceControllerFactoryInterface* ice_controller_factory = nullptr);
   bool IsGettingPorts() {
     RTC_DCHECK_RUN_ON(network_thread_);
     return allocator_session()->IsGettingPorts();
@@ -363,8 +403,10 @@ class RTC_EXPORT P2PTransportChannel : public IceTransportInternal {
   std::string transport_name_ RTC_GUARDED_BY(network_thread_);
   int component_ RTC_GUARDED_BY(network_thread_);
   PortAllocator* allocator_ RTC_GUARDED_BY(network_thread_);
-  webrtc::AsyncResolverFactory* async_resolver_factory_
+  webrtc::AsyncDnsResolverFactoryInterface* const async_dns_resolver_factory_
       RTC_GUARDED_BY(network_thread_);
+  const std::unique_ptr<webrtc::AsyncDnsResolverFactoryInterface>
+      owned_dns_resolver_factory_;
   rtc::Thread* const network_thread_;
   bool incoming_only_ RTC_GUARDED_BY(network_thread_);
   int error_ RTC_GUARDED_BY(network_thread_);
@@ -426,17 +468,23 @@ class RTC_EXPORT P2PTransportChannel : public IceTransportInternal {
       RTC_GUARDED_BY(network_thread_);
 
   struct CandidateAndResolver final {
-    CandidateAndResolver(const Candidate& candidate,
+    CandidateAndResolver(
-                         rtc::AsyncResolverInterface* resolver);
+        const Candidate& candidate,
+        std::unique_ptr<webrtc::AsyncDnsResolverInterface>&& resolver);
     ~CandidateAndResolver();
+    // Moveable, but not copyable.
+    CandidateAndResolver(CandidateAndResolver&&) = default;
+    CandidateAndResolver& operator=(CandidateAndResolver&&) = default;
+
     Candidate candidate_;
-    rtc::AsyncResolverInterface* resolver_;
+    std::unique_ptr<webrtc::AsyncDnsResolverInterface> resolver_;
   };
   std::vector<CandidateAndResolver> resolvers_ RTC_GUARDED_BY(network_thread_);
   void FinishAddingRemoteCandidate(const Candidate& new_remote_candidate);
-  void OnCandidateResolved(rtc::AsyncResolverInterface* resolver);
+  void OnCandidateResolved(webrtc::AsyncDnsResolverInterface* resolver);
-  void AddRemoteCandidateWithResolver(Candidate candidate,
+  void AddRemoteCandidateWithResult(
-                                      rtc::AsyncResolverInterface* resolver);
+      Candidate candidate,
+      const webrtc::AsyncDnsResolverResult& result);
 
   // Number of times the selected_connection_ has been modified.
   uint32_t selected_candidate_pair_changes_ = 0;

p2p/base/p2p_transport_channel_unittest.cc

@@ -14,6 +14,7 @@
 #include <memory>
 #include <utility>
 
+#include "api/test/mock_async_dns_resolver.h"
 #include "p2p/base/basic_ice_controller.h"
 #include "p2p/base/connection.h"
 #include "p2p/base/fake_port_allocator.h"
@@ -51,9 +52,12 @@ using ::testing::Assign;
 using ::testing::Contains;
 using ::testing::DoAll;
 using ::testing::InSequence;
+using ::testing::InvokeArgument;
 using ::testing::InvokeWithoutArgs;
 using ::testing::NiceMock;
 using ::testing::Return;
+using ::testing::ReturnRef;
+using ::testing::SaveArg;
 using ::testing::SetArgPointee;
 using ::testing::SizeIs;
 
@@ -187,6 +191,51 @@ class MockIceControllerFactory : public cricket::IceControllerFactoryInterface {
   MOCK_METHOD(void, RecordIceControllerCreated, ());
 };
 
+// An one-shot resolver factory with default return arguments.
+// Resolution is immediate, always succeeds, and returns nonsense.
+class ResolverFactoryFixture : public webrtc::MockAsyncDnsResolverFactory {
+ public:
+  ResolverFactoryFixture() {
+    mock_async_dns_resolver_ = std::make_unique<webrtc::MockAsyncDnsResolver>();
+    ON_CALL(*mock_async_dns_resolver_, Start(_, _))
+        .WillByDefault(InvokeArgument<1>());
+    EXPECT_CALL(*mock_async_dns_resolver_, result())
+        .WillOnce(ReturnRef(mock_async_dns_resolver_result_));
+
+    // A default action for GetResolvedAddress. Will be overruled
+    // by SetAddressToReturn.
+    ON_CALL(mock_async_dns_resolver_result_, GetResolvedAddress(_, _))
+        .WillByDefault(Return(true));
+
+    EXPECT_CALL(mock_async_dns_resolver_result_, GetError())
+        .WillOnce(Return(0));
+    EXPECT_CALL(*this, Create()).WillOnce([this]() {
+      return std::move(mock_async_dns_resolver_);
+    });
+  }
+
+  void SetAddressToReturn(rtc::SocketAddress address_to_return) {
+    EXPECT_CALL(mock_async_dns_resolver_result_, GetResolvedAddress(_, _))
+        .WillOnce(DoAll(SetArgPointee<1>(address_to_return), Return(true)));
+  }
+  void DelayResolution() {
+    // This function must be called before Create().
+    ASSERT_TRUE(!!mock_async_dns_resolver_);
+    EXPECT_CALL(*mock_async_dns_resolver_, Start(_, _))
+        .WillOnce(SaveArg<1>(&saved_callback_));
+  }
+  void FireDelayedResolution() {
+    // This function must be called after Create().
+    ASSERT_TRUE(saved_callback_);
+    saved_callback_();
+  }
+
+ private:
+  std::unique_ptr<webrtc::MockAsyncDnsResolver> mock_async_dns_resolver_;
+  webrtc::MockAsyncDnsResolverResult mock_async_dns_resolver_result_;
+  std::function<void()> saved_callback_;
+};
+
 }  // namespace
 
 namespace cricket {
@@ -345,7 +394,7 @@ class P2PTransportChannelTestBase : public ::testing::Test,
 
     rtc::FakeNetworkManager network_manager_;
     std::unique_ptr<BasicPortAllocator> allocator_;
-    webrtc::AsyncResolverFactory* async_resolver_factory_;
+    webrtc::AsyncDnsResolverFactoryInterface* async_dns_resolver_factory_;
     ChannelData cd1_;
     ChannelData cd2_;
     IceRole role_;
@@ -378,10 +427,10 @@ class P2PTransportChannelTestBase : public ::testing::Test,
         IceParamsWithRenomination(kIceParams[0], renomination);
     IceParameters ice_ep2_cd1_ch =
         IceParamsWithRenomination(kIceParams[1], renomination);
-    ep1_.cd1_.ch_.reset(CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
+    ep1_.cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-                                      ice_ep1_cd1_ch, ice_ep2_cd1_ch));
+                                  ice_ep1_cd1_ch, ice_ep2_cd1_ch);
-    ep2_.cd1_.ch_.reset(CreateChannel(1, ICE_CANDIDATE_COMPONENT_DEFAULT,
+    ep2_.cd1_.ch_ = CreateChannel(1, ICE_CANDIDATE_COMPONENT_DEFAULT,
-                                      ice_ep2_cd1_ch, ice_ep1_cd1_ch));
+                                  ice_ep2_cd1_ch, ice_ep1_cd1_ch);
     ep1_.cd1_.ch_->SetIceConfig(ep1_config);
     ep2_.cd1_.ch_->SetIceConfig(ep2_config);
     ep1_.cd1_.ch_->MaybeStartGathering();
@@ -397,13 +446,14 @@ class P2PTransportChannelTestBase : public ::testing::Test,
     CreateChannels(default_config, default_config, false);
   }
 
-  P2PTransportChannel* CreateChannel(int endpoint,
+  std::unique_ptr<P2PTransportChannel> CreateChannel(
+      int endpoint,
       int component,
       const IceParameters& local_ice,
       const IceParameters& remote_ice) {
-    P2PTransportChannel* channel = new P2PTransportChannel(
+    auto channel = P2PTransportChannel::Create(
         "test content name", component, GetAllocator(endpoint),
-        GetEndpoint(endpoint)->async_resolver_factory_);
+        GetEndpoint(endpoint)->async_dns_resolver_factory_);
     channel->SignalReadyToSend.connect(
         this, &P2PTransportChannelTestBase::OnReadyToSend);
     channel->SignalCandidateGathered.connect(
@@ -2079,8 +2129,8 @@ TEST_F(P2PTransportChannelTest, TurnToTurnPresumedWritable) {
                      kDefaultPortAllocatorFlags);
   // Only configure one channel so we can control when the remote candidate
   // is added.
-  GetEndpoint(0)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(0)->cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      0, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[0], kIceParams[1]));
+                                           kIceParams[0], kIceParams[1]);
   IceConfig config;
   config.presume_writable_when_fully_relayed = true;
   ep1_ch1()->SetIceConfig(config);
@@ -2128,10 +2178,10 @@ TEST_F(P2PTransportChannelTest, TurnToPrflxPresumedWritable) {
   test_turn_server()->set_enable_permission_checks(false);
   IceConfig config;
   config.presume_writable_when_fully_relayed = true;
-  GetEndpoint(0)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(0)->cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      0, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[0], kIceParams[1]));
+                                           kIceParams[0], kIceParams[1]);
-  GetEndpoint(1)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(1)->cd1_.ch_ = CreateChannel(1, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      1, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[1], kIceParams[0]));
+                                           kIceParams[1], kIceParams[0]);
   ep1_ch1()->SetIceConfig(config);
   ep2_ch1()->SetIceConfig(config);
   // Don't signal candidates from channel 2, so that channel 1 sees the TURN
@@ -2167,10 +2217,10 @@ TEST_F(P2PTransportChannelTest, PresumedWritablePreferredOverUnreliable) {
                      kDefaultPortAllocatorFlags);
   IceConfig config;
   config.presume_writable_when_fully_relayed = true;
-  GetEndpoint(0)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(0)->cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      0, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[0], kIceParams[1]));
+                                           kIceParams[0], kIceParams[1]);
-  GetEndpoint(1)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(1)->cd1_.ch_ = CreateChannel(1, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      1, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[1], kIceParams[0]));
+                                           kIceParams[1], kIceParams[0]);
   ep1_ch1()->SetIceConfig(config);
   ep2_ch1()->SetIceConfig(config);
   ep1_ch1()->MaybeStartGathering();
@@ -2205,8 +2255,8 @@ TEST_F(P2PTransportChannelTest, SignalReadyToSendWithPresumedWritable) {
                      kDefaultPortAllocatorFlags);
   // Only test one endpoint, so we can ensure the connection doesn't receive a
   // binding response and advance beyond being "presumed" writable.
-  GetEndpoint(0)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(0)->cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      0, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[0], kIceParams[1]));
+                                           kIceParams[0], kIceParams[1]);
   IceConfig config;
   config.presume_writable_when_fully_relayed = true;
   ep1_ch1()->SetIceConfig(config);
@@ -2258,10 +2308,10 @@ TEST_F(P2PTransportChannelTest,
   // to configure the server to accept packets from an address we haven't
   // explicitly installed permission for.
   test_turn_server()->set_enable_permission_checks(false);
-  GetEndpoint(0)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(0)->cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      0, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[0], kIceParams[1]));
+                                           kIceParams[0], kIceParams[1]);
-  GetEndpoint(1)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(1)->cd1_.ch_ = CreateChannel(1, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      1, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[1], kIceParams[0]));
+                                           kIceParams[1], kIceParams[0]);
   // Don't signal candidates from channel 2, so that channel 1 sees the TURN
   // candidate as peer reflexive.
   PauseCandidates(1);
@@ -4834,31 +4884,18 @@ TEST_F(P2PTransportChannelMostLikelyToWorkFirstTest, TestTcpTurn) {
 // when the address is a hostname. The destruction should happen even
 // if the channel is not destroyed.
 TEST(P2PTransportChannelResolverTest, HostnameCandidateIsResolved) {
-  rtc::MockAsyncResolver mock_async_resolver;
+  ResolverFactoryFixture resolver_fixture;
-  EXPECT_CALL(mock_async_resolver, GetError()).WillOnce(Return(0));
-  EXPECT_CALL(mock_async_resolver, GetResolvedAddress(_, _))
-      .WillOnce(Return(true));
-  // Destroy is called asynchronously after the address is resolved,
-  // so we need a variable to wait on.
-  bool destroy_called = false;
-  EXPECT_CALL(mock_async_resolver, Destroy(_))
-      .WillOnce(Assign(&destroy_called, true));
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(&mock_async_resolver));
-
   FakePortAllocator allocator(rtc::Thread::Current(), nullptr);
-  P2PTransportChannel channel("tn", 0, &allocator,
+  auto channel =
-                              &mock_async_resolver_factory);
+      P2PTransportChannel::Create("tn", 0, &allocator, &resolver_fixture);
   Candidate hostname_candidate;
   SocketAddress hostname_address("fake.test", 1000);
   hostname_candidate.set_address(hostname_address);
-  channel.AddRemoteCandidate(hostname_candidate);
+  channel->AddRemoteCandidate(hostname_candidate);
 
-  ASSERT_EQ_WAIT(1u, channel.remote_candidates().size(), kDefaultTimeout);
+  ASSERT_EQ_WAIT(1u, channel->remote_candidates().size(), kDefaultTimeout);
-  const RemoteCandidate& candidate = channel.remote_candidates()[0];
+  const RemoteCandidate& candidate = channel->remote_candidates()[0];
   EXPECT_FALSE(candidate.address().IsUnresolvedIP());
-  WAIT(destroy_called, kShortTimeout);
 }
 
 // Test that if we signal a hostname candidate after the remote endpoint
@@ -4867,11 +4904,6 @@ TEST(P2PTransportChannelResolverTest, HostnameCandidateIsResolved) {
 // done.
 TEST_F(P2PTransportChannelTest,
        PeerReflexiveCandidateBeforeSignalingWithMdnsName) {
-  rtc::MockAsyncResolver mock_async_resolver;
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(&mock_async_resolver));
-
   // ep1 and ep2 will only gather host candidates with addresses
   // kPublicAddrs[0] and kPublicAddrs[1], respectively.
   ConfigureEndpoints(OPEN, OPEN, kOnlyLocalPorts, kOnlyLocalPorts);
@@ -4879,7 +4911,9 @@ TEST_F(P2PTransportChannelTest,
   set_remote_ice_parameter_source(FROM_SETICEPARAMETERS);
   GetEndpoint(0)->network_manager_.set_mdns_responder(
       std::make_unique<webrtc::FakeMdnsResponder>(rtc::Thread::Current()));
-  GetEndpoint(1)->async_resolver_factory_ = &mock_async_resolver_factory;
+
+  ResolverFactoryFixture resolver_fixture;
+  GetEndpoint(1)->async_dns_resolver_factory_ = &resolver_fixture;
   CreateChannels();
   // Pause sending candidates from both endpoints until we find out what port
   // number is assgined to ep1's host candidate.
@@ -4894,6 +4928,7 @@ TEST_F(P2PTransportChannelTest,
   // This is the underlying private IP address of the same candidate at ep1.
   const auto local_address = rtc::SocketAddress(
       kPublicAddrs[0].ipaddr(), local_candidate.address().port());
+
   // Let ep2 signal its candidate to ep1. ep1 should form a candidate
   // pair and start to ping. After receiving the ping, ep2 discovers a prflx
   // remote candidate and form a candidate pair as well.
@@ -4909,19 +4944,7 @@ TEST_F(P2PTransportChannelTest,
   EXPECT_EQ(kIceUfrag[0], selected_connection->remote_candidate().username());
   EXPECT_EQ(kIcePwd[0], selected_connection->remote_candidate().password());
   // Set expectation before ep1 signals a hostname candidate.
-  {
+  resolver_fixture.SetAddressToReturn(local_address);
-    InSequence sequencer;
-    EXPECT_CALL(mock_async_resolver, Start(_));
-    EXPECT_CALL(mock_async_resolver, GetError()).WillOnce(Return(0));
-    // Let the mock resolver of ep2 receives the correct resolution.
-    EXPECT_CALL(mock_async_resolver, GetResolvedAddress(_, _))
-        .WillOnce(DoAll(SetArgPointee<1>(local_address), Return(true)));
-  }
-  // Destroy is called asynchronously after the address is resolved,
-  // so we need a variable to wait on.
-  bool destroy_called = false;
-  EXPECT_CALL(mock_async_resolver, Destroy(_))
-      .WillOnce(Assign(&destroy_called, true));
   ResumeCandidates(0);
   // Verify ep2's selected connection is updated to use the 'local' candidate.
   EXPECT_EQ_WAIT(LOCAL_PORT_TYPE,
@@ -4929,7 +4952,6 @@ TEST_F(P2PTransportChannelTest,
                  kMediumTimeout);
   EXPECT_EQ(selected_connection, ep2_ch1()->selected_connection());
 
-  WAIT(destroy_called, kShortTimeout);
   DestroyChannels();
 }
 
@@ -4939,13 +4961,9 @@ TEST_F(P2PTransportChannelTest,
 // address after the resolution completes.
 TEST_F(P2PTransportChannelTest,
        PeerReflexiveCandidateDuringResolvingHostCandidateWithMdnsName) {
-  auto mock_async_resolver = new NiceMock<rtc::MockAsyncResolver>();
+  ResolverFactoryFixture resolver_fixture;
-  ON_CALL(*mock_async_resolver, Destroy).WillByDefault([mock_async_resolver] {
+  // Prevent resolution until triggered by FireDelayedResolution.
-    delete mock_async_resolver;
+  resolver_fixture.DelayResolution();
-  });
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(mock_async_resolver));
 
   // ep1 and ep2 will only gather host candidates with addresses
   // kPublicAddrs[0] and kPublicAddrs[1], respectively.
@@ -4954,12 +4972,13 @@ TEST_F(P2PTransportChannelTest,
   set_remote_ice_parameter_source(FROM_SETICEPARAMETERS);
   GetEndpoint(0)->network_manager_.set_mdns_responder(
       std::make_unique<webrtc::FakeMdnsResponder>(rtc::Thread::Current()));
-  GetEndpoint(1)->async_resolver_factory_ = &mock_async_resolver_factory;
+  GetEndpoint(1)->async_dns_resolver_factory_ = &resolver_fixture;
   CreateChannels();
   // Pause sending candidates from both endpoints until we find out what port
   // number is assgined to ep1's host candidate.
   PauseCandidates(0);
   PauseCandidates(1);
+
   ASSERT_EQ_WAIT(1u, GetEndpoint(0)->saved_candidates_.size(), kMediumTimeout);
   ASSERT_EQ(1u, GetEndpoint(0)->saved_candidates_[0]->candidates.size());
   const auto& local_candidate =
@@ -4969,24 +4988,16 @@ TEST_F(P2PTransportChannelTest,
   // This is the underlying private IP address of the same candidate at ep1.
   const auto local_address = rtc::SocketAddress(
       kPublicAddrs[0].ipaddr(), local_candidate.address().port());
-  bool mock_async_resolver_started = false;
-  // Not signaling done yet, and only make sure we are in the process of
-  // resolution.
-  EXPECT_CALL(*mock_async_resolver, Start(_))
-      .WillOnce(InvokeWithoutArgs([&mock_async_resolver_started]() {
-        mock_async_resolver_started = true;
-      }));
   // Let ep1 signal its hostname candidate to ep2.
   ResumeCandidates(0);
-  ASSERT_TRUE_WAIT(mock_async_resolver_started, kMediumTimeout);
   // Now that ep2 is in the process of resolving the hostname candidate signaled
   // by ep1. Let ep2 signal its host candidate with an IP address to ep1, so
   // that ep1 can form a candidate pair, select it and start to ping ep2.
   ResumeCandidates(1);
   ASSERT_TRUE_WAIT(ep1_ch1()->selected_connection() != nullptr, kMediumTimeout);
   // Let the mock resolver of ep2 receives the correct resolution.
-  EXPECT_CALL(*mock_async_resolver, GetResolvedAddress(_, _))
+  resolver_fixture.SetAddressToReturn(local_address);
-      .WillOnce(DoAll(SetArgPointee<1>(local_address), Return(true)));
+
   // Upon receiving a ping from ep1, ep2 adds a prflx candidate from the
   // unknown address and establishes a connection.
   //
@@ -4997,7 +5008,9 @@ TEST_F(P2PTransportChannelTest,
             ep2_ch1()->selected_connection()->remote_candidate().type());
   // ep2 should also be able resolve the hostname candidate. The resolved remote
   // host candidate should be merged with the prflx remote candidate.
-  mock_async_resolver->SignalDone(mock_async_resolver);
+
+  resolver_fixture.FireDelayedResolution();
+
   EXPECT_EQ_WAIT(LOCAL_PORT_TYPE,
                  ep2_ch1()->selected_connection()->remote_candidate().type(),
                  kMediumTimeout);
@@ -5010,10 +5023,7 @@ TEST_F(P2PTransportChannelTest,
 // which is obfuscated by an mDNS name, and if the peer can complete the name
 // resolution with the correct IP address, we can have a p2p connection.
 TEST_F(P2PTransportChannelTest, CanConnectWithHostCandidateWithMdnsName) {
-  NiceMock<rtc::MockAsyncResolver> mock_async_resolver;
+  ResolverFactoryFixture resolver_fixture;
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(&mock_async_resolver));
 
   // ep1 and ep2 will only gather host candidates with addresses
   // kPublicAddrs[0] and kPublicAddrs[1], respectively.
@@ -5022,7 +5032,7 @@ TEST_F(P2PTransportChannelTest, CanConnectWithHostCandidateWithMdnsName) {
   set_remote_ice_parameter_source(FROM_SETICEPARAMETERS);
   GetEndpoint(0)->network_manager_.set_mdns_responder(
       std::make_unique<webrtc::FakeMdnsResponder>(rtc::Thread::Current()));
-  GetEndpoint(1)->async_resolver_factory_ = &mock_async_resolver_factory;
+  GetEndpoint(1)->async_dns_resolver_factory_ = &resolver_fixture;
   CreateChannels();
   // Pause sending candidates from both endpoints until we find out what port
   // number is assgined to ep1's host candidate.
@@ -5039,8 +5049,7 @@ TEST_F(P2PTransportChannelTest, CanConnectWithHostCandidateWithMdnsName) {
   rtc::SocketAddress resolved_address_ep1(local_candidate_ep1.address());
   resolved_address_ep1.SetResolvedIP(kPublicAddrs[0].ipaddr());
 
-  EXPECT_CALL(mock_async_resolver, GetResolvedAddress(_, _))
+  resolver_fixture.SetAddressToReturn(resolved_address_ep1);
-      .WillOnce(DoAll(SetArgPointee<1>(resolved_address_ep1), Return(true)));
   // Let ep1 signal its hostname candidate to ep2.
   ResumeCandidates(0);
 
@@ -5064,10 +5073,7 @@ TEST_F(P2PTransportChannelTest, CanConnectWithHostCandidateWithMdnsName) {
 // this remote host candidate in stats.
 TEST_F(P2PTransportChannelTest,
        CandidatesSanitizedInStatsWhenMdnsObfuscationEnabled) {
-  NiceMock<rtc::MockAsyncResolver> mock_async_resolver;
+  ResolverFactoryFixture resolver_fixture;
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(&mock_async_resolver));
 
   // ep1 and ep2 will gather host candidates with addresses
   // kPublicAddrs[0] and kPublicAddrs[1], respectively. ep1 also gathers a srflx
@@ -5079,7 +5085,7 @@ TEST_F(P2PTransportChannelTest,
   set_remote_ice_parameter_source(FROM_SETICEPARAMETERS);
   GetEndpoint(0)->network_manager_.set_mdns_responder(
       std::make_unique<webrtc::FakeMdnsResponder>(rtc::Thread::Current()));
-  GetEndpoint(1)->async_resolver_factory_ = &mock_async_resolver_factory;
+  GetEndpoint(1)->async_dns_resolver_factory_ = &resolver_fixture;
   CreateChannels();
   // Pause sending candidates from both endpoints until we find out what port
   // number is assigned to ep1's host candidate.
@@ -5097,9 +5103,7 @@ TEST_F(P2PTransportChannelTest,
       // and let the mock resolver of ep2 receive the correct resolution.
       rtc::SocketAddress resolved_address_ep1(local_candidate_ep1.address());
       resolved_address_ep1.SetResolvedIP(kPublicAddrs[0].ipaddr());
-      EXPECT_CALL(mock_async_resolver, GetResolvedAddress(_, _))
+      resolver_fixture.SetAddressToReturn(resolved_address_ep1);
-          .WillOnce(
-              DoAll(SetArgPointee<1>(resolved_address_ep1), Return(true)));
       break;
     }
   }
@@ -5248,10 +5252,7 @@ TEST_F(P2PTransportChannelTest,
 // when it is queried via GetSelectedCandidatePair.
 TEST_F(P2PTransportChannelTest,
        SelectedCandidatePairSanitizedWhenMdnsObfuscationEnabled) {
-  NiceMock<rtc::MockAsyncResolver> mock_async_resolver;
+  ResolverFactoryFixture resolver_fixture;
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(&mock_async_resolver));
 
   // ep1 and ep2 will gather host candidates with addresses
   // kPublicAddrs[0] and kPublicAddrs[1], respectively.
@@ -5260,7 +5261,7 @@ TEST_F(P2PTransportChannelTest,
   set_remote_ice_parameter_source(FROM_SETICEPARAMETERS);
   GetEndpoint(0)->network_manager_.set_mdns_responder(
       std::make_unique<webrtc::FakeMdnsResponder>(rtc::Thread::Current()));
-  GetEndpoint(1)->async_resolver_factory_ = &mock_async_resolver_factory;
+  GetEndpoint(1)->async_dns_resolver_factory_ = &resolver_fixture;
   CreateChannels();
   // Pause sending candidates from both endpoints until we find out what port
   // number is assigned to ep1's host candidate.
@@ -5275,8 +5276,8 @@ TEST_F(P2PTransportChannelTest,
   // and let the mock resolver of ep2 receive the correct resolution.
   rtc::SocketAddress resolved_address_ep1(local_candidate_ep1.address());
   resolved_address_ep1.SetResolvedIP(kPublicAddrs[0].ipaddr());
-  EXPECT_CALL(mock_async_resolver, GetResolvedAddress(_, _))
+  resolver_fixture.SetAddressToReturn(resolved_address_ep1);
-      .WillOnce(DoAll(SetArgPointee<1>(resolved_address_ep1), Return(true)));
+
   ResumeCandidates(0);
   ResumeCandidates(1);
 
@@ -5305,8 +5306,8 @@ TEST_F(P2PTransportChannelTest,
   // We use one endpoint to test the behavior of adding remote candidates, and
   // this endpoint only gathers relay candidates.
   ConfigureEndpoints(OPEN, OPEN, kOnlyRelayPorts, kDefaultPortAllocatorFlags);
-  GetEndpoint(0)->cd1_.ch_.reset(CreateChannel(
+  GetEndpoint(0)->cd1_.ch_ = CreateChannel(0, ICE_CANDIDATE_COMPONENT_DEFAULT,
-      0, ICE_CANDIDATE_COMPONENT_DEFAULT, kIceParams[0], kIceParams[1]));
+                                           kIceParams[0], kIceParams[1]);
   IceConfig config;
   // Start gathering and we should have only a single relay port.
   ep1_ch1()->SetIceConfig(config);
@@ -5869,21 +5870,21 @@ class ForgetLearnedStateControllerFactory
 TEST_F(P2PTransportChannelPingTest, TestForgetLearnedState) {
   ForgetLearnedStateControllerFactory factory;
   FakePortAllocator pa(rtc::Thread::Current(), nullptr);
-  P2PTransportChannel ch("ping sufficiently", 1, &pa, nullptr, nullptr,
+  auto ch = P2PTransportChannel::Create("ping sufficiently", 1, &pa, nullptr,
-                         &factory);
+                                        nullptr, &factory);
-  PrepareChannel(&ch);
+  PrepareChannel(ch.get());
-  ch.MaybeStartGathering();
+  ch->MaybeStartGathering();
-  ch.AddRemoteCandidate(CreateUdpCandidate(LOCAL_PORT_TYPE, "1.1.1.1", 1, 1));
+  ch->AddRemoteCandidate(CreateUdpCandidate(LOCAL_PORT_TYPE, "1.1.1.1", 1, 1));
-  ch.AddRemoteCandidate(CreateUdpCandidate(LOCAL_PORT_TYPE, "2.2.2.2", 2, 2));
+  ch->AddRemoteCandidate(CreateUdpCandidate(LOCAL_PORT_TYPE, "2.2.2.2", 2, 2));
 
-  Connection* conn1 = WaitForConnectionTo(&ch, "1.1.1.1", 1);
+  Connection* conn1 = WaitForConnectionTo(ch.get(), "1.1.1.1", 1);
-  Connection* conn2 = WaitForConnectionTo(&ch, "2.2.2.2", 2);
+  Connection* conn2 = WaitForConnectionTo(ch.get(), "2.2.2.2", 2);
   ASSERT_TRUE(conn1 != nullptr);
   ASSERT_TRUE(conn2 != nullptr);
 
   // Wait for conn1 to be selected.
   conn1->ReceivedPingResponse(LOW_RTT, "id");
-  EXPECT_EQ_WAIT(conn1, ch.selected_connection(), kMediumTimeout);
+  EXPECT_EQ_WAIT(conn1, ch->selected_connection(), kMediumTimeout);
 
   conn2->ReceivedPingResponse(LOW_RTT, "id");
   EXPECT_TRUE(conn2->writable());
@@ -5904,23 +5905,23 @@ TEST_F(P2PTransportChannelTest, DisableDnsLookupsWithTransportPolicyRelay) {
   auto* ep1 = GetEndpoint(0);
   ep1->allocator_->SetCandidateFilter(CF_RELAY);
 
-  rtc::MockAsyncResolver mock_async_resolver;
+  std::unique_ptr<webrtc::MockAsyncDnsResolver> mock_async_resolver =
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
+      std::make_unique<webrtc::MockAsyncDnsResolver>();
-  ON_CALL(mock_async_resolver_factory, Create())
+  // This test expects resolution to not be started.
-      .WillByDefault(Return(&mock_async_resolver));
+  EXPECT_CALL(*mock_async_resolver, Start(_, _)).Times(0);
-  ep1->async_resolver_factory_ = &mock_async_resolver_factory;
 
-  bool lookup_started = false;
+  webrtc::MockAsyncDnsResolverFactory mock_async_resolver_factory;
-  ON_CALL(mock_async_resolver, Start(_))
+  ON_CALL(mock_async_resolver_factory, Create())
-      .WillByDefault(Assign(&lookup_started, true));
+      .WillByDefault(
+          [&mock_async_resolver]() { return std::move(mock_async_resolver); });
+
+  ep1->async_dns_resolver_factory_ = &mock_async_resolver_factory;
 
   CreateChannels();
 
   ep1_ch1()->AddRemoteCandidate(
       CreateUdpCandidate(LOCAL_PORT_TYPE, "hostname.test", 1, 100));
 
-  EXPECT_FALSE(lookup_started);
-
   DestroyChannels();
 }
 
@@ -5930,23 +5931,23 @@ TEST_F(P2PTransportChannelTest, DisableDnsLookupsWithTransportPolicyNone) {
   auto* ep1 = GetEndpoint(0);
   ep1->allocator_->SetCandidateFilter(CF_NONE);
 
-  rtc::MockAsyncResolver mock_async_resolver;
+  std::unique_ptr<webrtc::MockAsyncDnsResolver> mock_async_resolver =
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
+      std::make_unique<webrtc::MockAsyncDnsResolver>();
-  ON_CALL(mock_async_resolver_factory, Create())
+  // This test expects resolution to not be started.
-      .WillByDefault(Return(&mock_async_resolver));
+  EXPECT_CALL(*mock_async_resolver, Start(_, _)).Times(0);
-  ep1->async_resolver_factory_ = &mock_async_resolver_factory;
 
-  bool lookup_started = false;
+  webrtc::MockAsyncDnsResolverFactory mock_async_resolver_factory;
-  ON_CALL(mock_async_resolver, Start(_))
+  ON_CALL(mock_async_resolver_factory, Create())
-      .WillByDefault(Assign(&lookup_started, true));
+      .WillByDefault(
+          [&mock_async_resolver]() { return std::move(mock_async_resolver); });
+
+  ep1->async_dns_resolver_factory_ = &mock_async_resolver_factory;
 
   CreateChannels();
 
   ep1_ch1()->AddRemoteCandidate(
       CreateUdpCandidate(LOCAL_PORT_TYPE, "hostname.test", 1, 100));
 
-  EXPECT_FALSE(lookup_started);
-
   DestroyChannels();
 }
 
@@ -5956,18 +5957,19 @@ TEST_F(P2PTransportChannelTest, EnableDnsLookupsWithTransportPolicyNoHost) {
   auto* ep1 = GetEndpoint(0);
   ep1->allocator_->SetCandidateFilter(CF_ALL & ~CF_HOST);
 
-  rtc::MockAsyncResolver mock_async_resolver;
+  std::unique_ptr<webrtc::MockAsyncDnsResolver> mock_async_resolver =
-  webrtc::MockAsyncResolverFactory mock_async_resolver_factory;
+      std::make_unique<webrtc::MockAsyncDnsResolver>();
-  EXPECT_CALL(mock_async_resolver_factory, Create())
-      .WillOnce(Return(&mock_async_resolver));
-  EXPECT_CALL(mock_async_resolver, Destroy(_));
-
-  ep1->async_resolver_factory_ = &mock_async_resolver_factory;
-
   bool lookup_started = false;
-  EXPECT_CALL(mock_async_resolver, Start(_))
+  EXPECT_CALL(*mock_async_resolver, Start(_, _))
       .WillOnce(Assign(&lookup_started, true));
 
+  webrtc::MockAsyncDnsResolverFactory mock_async_resolver_factory;
+  EXPECT_CALL(mock_async_resolver_factory, Create())
+      .WillOnce(
+          [&mock_async_resolver]() { return std::move(mock_async_resolver); });
+
+  ep1->async_dns_resolver_factory_ = &mock_async_resolver_factory;
+
   CreateChannels();
 
   ep1_ch1()->AddRemoteCandidate(

pc/BUILD.gn

@@ -77,6 +77,7 @@ rtc_library("rtc_pc_base") {
   deps = [
     ":media_protocol_names",
     "../api:array_view",
+    "../api:async_dns_resolver",
     "../api:audio_options_api",
     "../api:call_api",
     "../api:function_view",
@@ -236,6 +237,7 @@ rtc_library("peerconnection") {
     ":video_track",
     ":video_track_source",
     "../api:array_view",
+    "../api:async_dns_resolver",
     "../api:audio_options_api",
     "../api:call_api",
     "../api:callfactory_api",

pc/jsep_transport_controller.cc

@@ -39,11 +39,11 @@ namespace webrtc {
 JsepTransportController::JsepTransportController(
     rtc::Thread* network_thread,
     cricket::PortAllocator* port_allocator,
-    AsyncResolverFactory* async_resolver_factory,
+    AsyncDnsResolverFactoryInterface* async_dns_resolver_factory,
     Config config)
     : network_thread_(network_thread),
       port_allocator_(port_allocator),
-      async_resolver_factory_(async_resolver_factory),
+      async_dns_resolver_factory_(async_dns_resolver_factory),
       config_(config),
       active_reset_srtp_params_(config.active_reset_srtp_params) {
   // The |transport_observer| is assumed to be non-null.
@@ -398,7 +398,7 @@ JsepTransportController::CreateIceTransport(const std::string& transport_name,
 
   IceTransportInit init;
   init.set_port_allocator(port_allocator_);
-  init.set_async_resolver_factory(async_resolver_factory_);
+  init.set_async_dns_resolver_factory(async_dns_resolver_factory_);
   init.set_event_log(config_.event_log);
   return config_.ice_transport_factory->CreateIceTransport(
       transport_name, component, std::move(init));

pc/jsep_transport_controller.h

@@ -21,7 +21,7 @@
 #include <vector>
 
 #include "absl/types/optional.h"
-#include "api/async_resolver_factory.h"
+#include "api/async_dns_resolver.h"
 #include "api/candidate.h"
 #include "api/crypto/crypto_options.h"
 #include "api/ice_transport_factory.h"
@@ -140,9 +140,10 @@ class JsepTransportController : public sigslot::has_slots<> {
   // All the transport related methods are called on the |network_thread|
   // and destruction of the JsepTransportController must occur on the
   // |network_thread|.
-  JsepTransportController(rtc::Thread* network_thread,
+  JsepTransportController(
+      rtc::Thread* network_thread,
       cricket::PortAllocator* port_allocator,
-                          AsyncResolverFactory* async_resolver_factory,
+      AsyncDnsResolverFactoryInterface* async_dns_resolver_factory,
       Config config);
   virtual ~JsepTransportController();
 
@@ -461,7 +462,7 @@ class JsepTransportController : public sigslot::has_slots<> {
 
   rtc::Thread* const network_thread_ = nullptr;
   cricket::PortAllocator* const port_allocator_ = nullptr;
-  AsyncResolverFactory* const async_resolver_factory_ = nullptr;
+  AsyncDnsResolverFactoryInterface* const async_dns_resolver_factory_ = nullptr;
 
   std::map<std::string, std::unique_ptr<cricket::JsepTransport>>
       jsep_transports_by_name_ RTC_GUARDED_BY(network_thread_);

pc/peer_connection.cc

@@ -12,6 +12,7 @@
 
 #include <limits.h>
 #include <stddef.h>
+
 #include <algorithm>
 #include <memory>
 #include <set>
@@ -33,6 +34,7 @@
 #include "media/base/rid_description.h"
 #include "media/base/stream_params.h"
 #include "modules/rtp_rtcp/include/rtp_rtcp_defines.h"
+#include "p2p/base/basic_async_resolver_factory.h"
 #include "p2p/base/connection.h"
 #include "p2p/base/connection_info.h"
 #include "p2p/base/dtls_transport_internal.h"
@@ -435,6 +437,30 @@ RTCErrorOr<rtc::scoped_refptr<PeerConnection>> PeerConnection::Create(
   bool is_unified_plan =
       configuration.sdp_semantics == SdpSemantics::kUnifiedPlan;
   bool dtls_enabled = DtlsEnabled(configuration, options, dependencies);
+
+  // Interim code: If an AsyncResolverFactory is given, but not an
+  // AsyncDnsResolverFactory, wrap it in a WrappingAsyncDnsResolverFactory
+  // If neither is given, create a WrappingAsyncDnsResolverFactory wrapping
+  // a BasicAsyncResolver.
+  // TODO(bugs.webrtc.org/12598): Remove code once all callers pass a
+  // AsyncDnsResolverFactory.
+  if (dependencies.async_dns_resolver_factory &&
+      dependencies.async_resolver_factory) {
+    RTC_LOG(LS_ERROR)
+        << "Attempt to set both old and new type of DNS resolver factory";
+    return RTCError(RTCErrorType::INVALID_PARAMETER,
+                    "Both old and new type of DNS resolver given");
+  }
+  if (dependencies.async_resolver_factory) {
+    dependencies.async_dns_resolver_factory =
+        std::make_unique<WrappingAsyncDnsResolverFactory>(
+            std::move(dependencies.async_resolver_factory));
+  } else {
+    dependencies.async_dns_resolver_factory =
+        std::make_unique<WrappingAsyncDnsResolverFactory>(
+            std::make_unique<BasicAsyncResolverFactory>());
+  }
+
   // The PeerConnection constructor consumes some, but not all, dependencies.
   rtc::scoped_refptr<PeerConnection> pc(
       new rtc::RefCountedObject<PeerConnection>(
@@ -462,7 +488,8 @@ PeerConnection::PeerConnection(
       is_unified_plan_(is_unified_plan),
       event_log_(std::move(event_log)),
       event_log_ptr_(event_log_.get()),
-      async_resolver_factory_(std::move(dependencies.async_resolver_factory)),
+      async_dns_resolver_factory_(
+          std::move(dependencies.async_dns_resolver_factory)),
       port_allocator_(std::move(dependencies.allocator)),
       ice_transport_factory_(std::move(dependencies.ice_transport_factory)),
       tls_cert_verifier_(std::move(dependencies.tls_cert_verifier)),
@@ -672,7 +699,7 @@ void PeerConnection::InitializeTransportController_n(
 
   transport_controller_.reset(
       new JsepTransportController(network_thread(), port_allocator_.get(),
-                                  async_resolver_factory_.get(), config));
+                                  async_dns_resolver_factory_.get(), config));
 
   transport_controller_->SubscribeIceConnectionState(
       [this](cricket::IceConnectionState s) {

pc/peer_connection.h

@@ -23,6 +23,7 @@
 
 #include "absl/types/optional.h"
 #include "api/adaptation/resource.h"
+#include "api/async_dns_resolver.h"
 #include "api/async_resolver_factory.h"
 #include "api/audio_options.h"
 #include "api/candidate.h"
@@ -637,11 +638,8 @@ class PeerConnection : public PeerConnectionInternal,
   PeerConnectionInterface::RTCConfiguration configuration_
       RTC_GUARDED_BY(signaling_thread());
 
-  // TODO(zstein): |async_resolver_factory_| can currently be nullptr if it
+  const std::unique_ptr<AsyncDnsResolverFactoryInterface>
-  // is not injected. It should be required once chromium supplies it.
+      async_dns_resolver_factory_;
-  // This member variable is only used by JsepTransportController so we should
-  // consider moving ownership to there.
-  const std::unique_ptr<AsyncResolverFactory> async_resolver_factory_;
   std::unique_ptr<cricket::PortAllocator>
       port_allocator_;  // TODO(bugs.webrtc.org/9987): Accessed on both
                         // signaling and network thread.