Merge pull request #26 from hai007/cl-345608764

Roll forward to Cl/345608764

cpp/core/BUILD

@@ -21,7 +21,7 @@ cc_library(
         "core.h",
     ],
     visibility = [
-        "//googlemac/iPhone/Shared/Nearby/Connections:__subpackages__",
+        "//googlemac/iPhone/Shared/Nearby/Connections_v2:__subpackages__",
     ],
     deps = [
         ":core_types",

cpp/core/internal/base_endpoint_channel.cc

@@ -259,6 +259,11 @@ std::string BaseEndpointChannel::GetType() const {
 
 std::string BaseEndpointChannel::GetName() const { return channel_name_; }
 
+int BaseEndpointChannel::GetMaxTransmitPacketSize() const {
+  // Return default value if the medium never define it's chunk size.
+  return kDefaultMaxTransmitPacketSize;
+}
+
 void BaseEndpointChannel::EnableEncryption(
     std::shared_ptr<EncryptionContext> context) {
   MutexLock crypto_lock(&crypto_mutex_);

cpp/core/internal/base_endpoint_channel.h

@@ -62,6 +62,10 @@ class BaseEndpointChannel : public EndpointChannel {
   // Returns the name of the EndpointChannel.
   std::string GetName() const override;
 
+  // Returns the maximum supported transmit packet size(MTU) for the underlying
+  // transport.
+  int GetMaxTransmitPacketSize() const override;
+
   // Enables encryption on the EndpointChannel.
   // Should be called after connection is accepted by both parties, and
   // before entering data phase, where Payloads may be exchanged.
@@ -92,6 +96,9 @@ class BaseEndpointChannel : public EndpointChannel {
   // Used to sanity check that our frame sizes are reasonable.
   static constexpr std::int32_t kMaxAllowedReadBytes = 1048576;  // 1MB
 
+  // The default maximum transmit unit/packet size.
+  static constexpr int kDefaultMaxTransmitPacketSize = 65536;  // 64 KB
+
   bool IsEncryptionEnabledLocked() const
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(crypto_mutex_);
   void UnblockPausedWriter() ABSL_EXCLUSIVE_LOCKS_REQUIRED(is_paused_mutex_);

cpp/core/internal/ble_endpoint_channel.cc

@@ -47,6 +47,10 @@ proto::connections::Medium BleEndpointChannel::GetMedium() const {
   return proto::connections::Medium::BLE;
 }
 
+int BleEndpointChannel::GetMaxTransmitPacketSize() const {
+  return kDefaultBleMaxTransmitPacketSize;
+}
+
 void BleEndpointChannel::CloseImpl() {
   auto status = ble_socket_.Close();
   if (!status.Ok()) {

cpp/core/internal/ble_endpoint_channel.h

@@ -30,7 +30,11 @@ class BleEndpointChannel final : public BaseEndpointChannel {
 
   proto::connections::Medium GetMedium() const override;
 
+  int GetMaxTransmitPacketSize() const override;
+
  private:
+  static constexpr int kDefaultBleMaxTransmitPacketSize = 512;  // 512 bytes
+
   void CloseImpl() override;
 
   BleSocket ble_socket_;

cpp/core/internal/bluetooth_endpoint_channel.cc

@@ -47,6 +47,10 @@ proto::connections::Medium BluetoothEndpointChannel::GetMedium() const {
   return proto::connections::Medium::BLUETOOTH;
 }
 
+int BluetoothEndpointChannel::GetMaxTransmitPacketSize() const {
+  return kDefaultBTMaxTransmitPacketSize;
+}
+
 void BluetoothEndpointChannel::CloseImpl() {
   auto status = bluetooth_socket_.Close();
   if (!status.Ok()) {

cpp/core/internal/bluetooth_endpoint_channel.h

@@ -33,7 +33,11 @@ class BluetoothEndpointChannel final : public BaseEndpointChannel {
 
   proto::connections::Medium GetMedium() const override;
 
+  int GetMaxTransmitPacketSize() const override;
+
  private:
+  static constexpr int kDefaultBTMaxTransmitPacketSize = 1980;  // 990 * 2 Bytes
+
   void CloseImpl() override;
 
   BluetoothSocket bluetooth_socket_;

cpp/core/internal/encryption_runner_test.cc

@@ -54,6 +54,7 @@ class FakeEndpointChannel : public EndpointChannel {
   std::string GetType() const override { return "fake-channel-type"; }
   std::string GetName() const override { return "fake-channel"; }
   Medium GetMedium() const override { return Medium::BLE; }
+  int GetMaxTransmitPacketSize() const override { return 512; }
   void EnableEncryption(std::shared_ptr<EncryptionContext> context) override {}
   void DisableEncryption() override {}
   bool IsPaused() const override { return false; }

cpp/core/internal/endpoint_channel.h

@@ -56,6 +56,10 @@ class EndpointChannel {
   // Returns the analytics enum representing the medium of this EndpointChannel.
   virtual proto::connections::Medium GetMedium() const = 0;
 
+  // Returns the maximum supported transmit packet size(MTU) for the underlying
+  // transport.
+  virtual int GetMaxTransmitPacketSize() const = 0;
+
   // Enables encryption on the EndpointChannel.
   virtual void EnableEncryption(std::shared_ptr<EncryptionContext> context) = 0;
 

cpp/core/internal/endpoint_manager.cc

@@ -417,16 +417,14 @@ void EndpointManager::UnregisterEndpoint(ClientProxy* client,
   latch.Await();
 }
 
-// Designed to run asynchronously. It is called from IO thread pools, and
-// jobs in these pools may be waited for from the EndpointManager thread. If we
-// allow synchronous behavior here it will cause a live lock.
-void EndpointManager::DiscardEndpoint(ClientProxy* client,
-                                      const std::string& endpoint_id) {
-  RunOnEndpointManagerThread([this, client, endpoint_id]() {
-    RemoveEndpoint(client, endpoint_id,
-                   /*notify=*/
-                   client->IsConnectedToEndpoint(endpoint_id));
-  });
+int EndpointManager::GetMaxTransmitPacketSize(const std::string& endpoint_id) {
+  std::shared_ptr<EndpointChannel> channel =
+      channel_manager_->GetChannelForEndpoint(endpoint_id);
+  if (channel == nullptr) {
+    return 0;
+  }
+
+  return channel->GetMaxTransmitPacketSize();
 }
 
 std::vector<std::string> EndpointManager::SendPayloadChunk(
@@ -441,6 +439,18 @@ std::vector<std::string> EndpointManager::SendPayloadChunk(
                                 /*packet_type=*/"DATA");
 }
 
+// Designed to run asynchronously. It is called from IO thread pools, and
+// jobs in these pools may be waited for from the EndpointManager thread. If we
+// allow synchronous behavior here it will cause a live lock.
+void EndpointManager::DiscardEndpoint(ClientProxy* client,
+                                      const std::string& endpoint_id) {
+  RunOnEndpointManagerThread([this, client, endpoint_id]() {
+    RemoveEndpoint(client, endpoint_id,
+                   /*notify=*/
+                   client->IsConnectedToEndpoint(endpoint_id));
+  });
+}
+
 std::vector<std::string> EndpointManager::SendControlMessage(
     const PayloadTransferFrame::PayloadHeader& header,
     const PayloadTransferFrame::ControlMessage& control,

cpp/core/internal/endpoint_manager.h

@@ -112,6 +112,10 @@ class EndpointManager {
   // this case, we do not notify the client of onDisconnected().
   void UnregisterEndpoint(ClientProxy* client, const std::string& endpoint_id);
 
+  // Returns the maximum supported transmit packet size(MTU) for the underlying
+  // transport.
+  int GetMaxTransmitPacketSize(const std::string& endpoint_id);
+
   // Returns the list of endpoints to which sending this chunk failed.
   //
   // Invoked from the PayloadManager's sendPayload() method.

cpp/core/internal/endpoint_manager_test.cc

@@ -54,6 +54,7 @@ class MockEndpointChannel : public EndpointChannel {
   MOCK_METHOD(std::string, GetType, (), (const override));
   MOCK_METHOD(std::string, GetName, (), (const override));
   MOCK_METHOD(Medium, GetMedium, (), (const override));
+  MOCK_METHOD(int, GetMaxTransmitPacketSize, (), (const override));
   MOCK_METHOD(void, EnableEncryption,
               (std::shared_ptr<EncryptionContext> context), (override));
   MOCK_METHOD(void, DisableEncryption, (), (override));

cpp/core/internal/internal_payload.h

@@ -63,8 +63,10 @@ class InternalPayload {
   // byte blobs for sending across a hard boundary (like the other side of
   // a Binder, or another device altogether).
   //
+  // @param chunk_size The preferred size of the next chunk. Depending on
+  // payload type, the provided size may be ignored.
   // @return The next chunk from the Payload, or null if we've reached the end.
-  virtual ByteArray DetachNextChunk() = 0;
+  virtual ByteArray DetachNextChunk(int chunk_size) = 0;
 
   // Adds the next chunk that comprises the Payload to which this object is
   // bound.

cpp/core/internal/internal_payload_factory.cc

@@ -22,6 +22,7 @@
 #include "platform/base/exception.h"
 #include "platform/public/condition_variable.h"
 #include "platform/public/file.h"
+#include "platform/public/logging.h"
 #include "platform/public/mutex.h"
 #include "platform/public/pipe.h"
 #include "absl/memory/memory.h"
@@ -47,7 +48,7 @@ class BytesInternalPayload : public InternalPayload {
 
   // Relinquishes ownership of the payload_; retrieves and returns the stored
   // ByteArray.
-  ByteArray DetachNextChunk() override {
+  ByteArray DetachNextChunk(int chunk_size) override {
     if (detached_only_chunk_) {
       return {};
     }
@@ -80,11 +81,11 @@ class OutgoingStreamInternalPayload : public InternalPayload {
 
   std::int64_t GetTotalSize() const override { return -1; }
 
-  ByteArray DetachNextChunk() override {
+  ByteArray DetachNextChunk(int chunk_size) override {
     InputStream* input_stream = payload_.AsStream();
     if (!input_stream) return {};
 
-    ExceptionOr<ByteArray> bytes_read = input_stream->Read(kChunkSize);
+    ExceptionOr<ByteArray> bytes_read = input_stream->Read(chunk_size);
     if (!bytes_read.ok()) {
       input_stream->Close();
       return {};
@@ -93,8 +94,8 @@ class OutgoingStreamInternalPayload : public InternalPayload {
     ByteArray scoped_bytes_read = std::move(bytes_read.result());
 
     if (scoped_bytes_read.Empty()) {
-      // TODO(reznor): logger.atVerbose().log("No more data for outgoing payload
-      // %s, closing InputStream.", this);
+      NEARBY_LOGS(INFO) << "No more data for outgoing payload " << this
+                        << ", closing InputStream.";
 
       input_stream->Close();
       return {};
@@ -113,9 +114,6 @@ class OutgoingStreamInternalPayload : public InternalPayload {
     InputStream* stream = payload_.AsStream();
     if (stream) stream->Close();
   }
-
- private:
-  static constexpr std::int64_t kChunkSize = Pipe::kChunkSize;
 };
 
 class IncomingStreamInternalPayload : public InternalPayload {
@@ -129,7 +127,7 @@ class IncomingStreamInternalPayload : public InternalPayload {
 
   std::int64_t GetTotalSize() const override { return -1; }
 
-  ByteArray DetachNextChunk() override { return {}; }
+  ByteArray DetachNextChunk(int chunk_size) override { return {}; }
 
   Exception AttachNextChunk(const ByteArray& chunk) override {
     if (chunk.Empty()) {
@@ -158,11 +156,11 @@ class OutgoingFileInternalPayload : public InternalPayload {
 
   std::int64_t GetTotalSize() const override { return total_size_; }
 
-  ByteArray DetachNextChunk() override {
+  ByteArray DetachNextChunk(int chunk_size) override {
     InputFile* file = payload_.AsFile();
     if (!file) return {};
 
-    ExceptionOr<ByteArray> bytes_read = file->Read(kChunkSize);
+    ExceptionOr<ByteArray> bytes_read = file->Read(chunk_size);
     if (!bytes_read.ok()) {
       return {};
     }
@@ -190,7 +188,6 @@ class OutgoingFileInternalPayload : public InternalPayload {
 
  private:
   std::int64_t total_size_;
-  static constexpr std::int64_t kChunkSize = 64 * 1024;
 };
 
 class IncomingFileInternalPayload : public InternalPayload {
@@ -207,7 +204,7 @@ class IncomingFileInternalPayload : public InternalPayload {
 
   std::int64_t GetTotalSize() const override { return total_size_; }
 
-  ByteArray DetachNextChunk() override { return {}; }
+  ByteArray DetachNextChunk(int chunk_size) override { return {}; }
 
   Exception AttachNextChunk(const ByteArray& chunk) override {
     if (chunk.Empty()) {

cpp/core/internal/mediums/webrtc.cc

@@ -26,6 +26,7 @@
 #include "platform/public/logging.h"
 #include "platform/public/mutex_lock.h"
 #include "location/nearby/mediums/proto/web_rtc_signaling_frames.pb.h"
+#include "absl/container/flat_hash_map.h"
 #include "absl/strings/str_cat.h"
 #include "absl/time/time.h"
 #include "webrtc/api/jsep.h"
@@ -53,7 +54,23 @@ WebRtc::~WebRtc() {
   restart_receive_messages_executor_.Shutdown();
   single_thread_executor_.Shutdown();
 
-  Disconnect();
+  // Disconnect will also erase the connection info from map. Use a separate
+  // set to save the connection ids to avoid the iterator violation issue.
+  absl::flat_hash_set<std::string> connection_ids;
+  for (auto& item : accepting_map_) {
+    connection_ids.emplace(item.first);
+  }
+  for (const auto& connection_id : connection_ids) {
+    Disconnect(Role::kOfferer, connection_id);
+  }
+  connection_ids.clear();
+  for (auto& item : connecting_map_) {
+    connection_ids.emplace(item.first);
+  }
+  for (const auto& connection_id : connection_ids) {
+    Disconnect(Role::kAnswerer, connection_id);
+  }
+  connection_ids.clear();
 }
 
 const std::string WebRtc::GetDefaultCountryCode() {
@@ -64,8 +81,9 @@ bool WebRtc::IsAvailable() { return medium_.IsValid(); }
 
 bool WebRtc::IsAcceptingConnections(const std::string& service_id) {
   MutexLock lock(&mutex_);
-  // TODO(hais): refractor the implementation with maps.
-  return role_ == Role::kOfferer;
+  ConnectionInfo* connection_info =
+      GetConnectionInfo(Role::kOfferer, service_id);
+  return connection_info && connection_info->self_id.IsValid();
 }
 
 bool WebRtc::StartAcceptingConnections(const std::string& service_id,
@@ -73,10 +91,9 @@ bool WebRtc::StartAcceptingConnections(const std::string& service_id,
                                        const LocationHint& location_hint,
                                        AcceptedConnectionCallback callback) {
   if (!IsAvailable()) {
-    {
-      MutexLock lock(&mutex_);
-      LogAndDisconnect("WebRTC is not available for data transfer.");
-    }
+    MutexLock lock(&mutex_);
+    LogAndDisconnect(Role::kOfferer, service_id,
+                     "WebRTC is not available for data transfer.");
     return false;
   }
 
@@ -84,35 +101,36 @@ bool WebRtc::StartAcceptingConnections(const std::string& service_id,
     NEARBY_LOG(WARNING, "Already accepting WebRTC connections.");
     return false;
   }
-
   {
     MutexLock lock(&mutex_);
-    if (role_ != Role::kNone) {
-      NEARBY_LOG(WARNING,
-                 "Cannot start accepting WebRTC connections, current role %d",
-                 role_);
+    accepting_map_.emplace(service_id,
+                           ConnectionInfo{.socket = WebRtcSocketWrapper()});
+    ConnectionInfo* connection_info = &accepting_map_[service_id];
+    if (!InitWebRtcFlow(Role::kOfferer, self_id, location_hint, service_id))
       return false;
-    }
 
-    if (!InitWebRtcFlow(Role::kOfferer, self_id, location_hint)) return false;
-
-    restart_receive_messages_alarm_ = CancelableAlarm(
+    connection_info->restart_receive_messages_alarm = CancelableAlarm(
         "restart_receiving_messages_webrtc",
         std::bind(&WebRtc::RestartReceiveMessages, this, location_hint,
                   service_id),
         kRestartReceiveMessagesDuration, &restart_receive_messages_executor_);
 
-    SessionDescriptionWrapper offer = connection_flow_->CreateOffer();
-    pending_local_offer_ = webrtc_frames::EncodeOffer(self_id, offer.GetSdp());
-    if (!SetLocalSessionDescription(std::move(offer))) {
+    SessionDescriptionWrapper offer =
+        connection_info->connection_flow->CreateOffer();
+    connection_info->pending_local_offer =
+        webrtc_frames::EncodeOffer(self_id, offer.GetSdp());
+    if (!SetLocalSessionDescription(std::move(offer), Role::kOfferer,
+                                    service_id)) {
       return false;
     }
 
     // There is no timeout set for the future returned since we do not know how
     // much time it will take for the two devices to discover each other before
     // the actual transport can begin.
-    ListenForWebRtcSocketFuture(connection_flow_->GetDataChannel(),
-                                std::move(callback));
+    ListenForWebRtcSocketFuture(
+        Role::kOfferer, service_id,
+        connection_info->connection_flow->GetDataChannel(),
+        std::move(callback));
     NEARBY_LOG(INFO, "Started listening for WebRtc connections as %s",
                self_id.GetId().c_str());
   }
@@ -123,31 +141,38 @@ bool WebRtc::StartAcceptingConnections(const std::string& service_id,
 WebRtcSocketWrapper WebRtc::Connect(const PeerId& peer_id,
                                     const LocationHint& location_hint) {
   if (!IsAvailable()) {
-    Disconnect();
+    Disconnect(Role::kAnswerer, peer_id.GetId());
     return WebRtcSocketWrapper();
   }
 
   {
     MutexLock lock(&mutex_);
-    if (role_ != Role::kNone) {
+    if (connecting_map_.contains(peer_id.GetId())) {
       NEARBY_LOG(
-          WARNING,
-          "Cannot connect with WebRtc because we are already acting as %d",
-          role_);
+          ERROR,
+          "Cannot connect with WebRtc because we are already connecting.");
       return WebRtcSocketWrapper();
     }
-
-    peer_id_ = peer_id;
-    if (!InitWebRtcFlow(Role::kAnswerer, PeerId::FromRandom(), location_hint)) {
+    connecting_map_.emplace(peer_id.GetId(),
+                            ConnectionInfo{.socket = WebRtcSocketWrapper()});
+    ConnectionInfo* connection_info = &connecting_map_[peer_id.GetId()];
+    connection_info->peer_id = peer_id;
+    if (!InitWebRtcFlow(Role::kAnswerer, PeerId::FromRandom(), location_hint,
+                        peer_id.GetId())) {
       return WebRtcSocketWrapper();
     }
   }
 
-  NEARBY_LOG(INFO, "Attempting to make a WebRTC connection to %s.",
+  NEARBY_LOG(ERROR, "Attempting to make a WebRTC connection to %s.",
              peer_id.GetId().c_str());
-
-  Future<WebRtcSocketWrapper> socket_future = ListenForWebRtcSocketFuture(
-      connection_flow_->GetDataChannel(), AcceptedConnectionCallback());
+  Future<WebRtcSocketWrapper> socket_future;
+  {
+    MutexLock lock(&mutex_);
+    socket_future = ListenForWebRtcSocketFuture(
+        Role::kAnswerer, peer_id.GetId(),
+        connecting_map_[peer_id.GetId()].connection_flow->GetDataChannel(),
+        AcceptedConnectionCallback());
+  }
 
   // The two devices have discovered each other, hence we have a timeout for
   // establishing the transport channel.
@@ -158,13 +183,19 @@ WebRtcSocketWrapper WebRtc::Connect(const PeerId& peer_id,
       socket_future.Get(kDataChannelTimeout);
   if (result.ok()) return result.result();
 
-  Disconnect();
+  Disconnect(Role::kAnswerer, peer_id.GetId());
   return WebRtcSocketWrapper();
 }
 
-bool WebRtc::SetLocalSessionDescription(SessionDescriptionWrapper sdp) {
-  if (!connection_flow_->SetLocalSessionDescription(std::move(sdp))) {
-    LogAndDisconnect("Unable to set local session description");
+bool WebRtc::SetLocalSessionDescription(SessionDescriptionWrapper sdp,
+                                        Role role,
+                                        const std::string& connection_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (!connection_info) return false;
+  if (!connection_info->connection_flow->SetLocalSessionDescription(
+          std::move(sdp))) {
+    LogAndDisconnect(role, connection_id,
+                     "Unable to set local session description");
     return false;
   }
 
@@ -182,28 +213,35 @@ void WebRtc::StopAcceptingConnections(const std::string& service_id) {
 
   {
     MutexLock lock(&mutex_);
-    ShutdownSignaling();
+    ShutdownSignaling(Role::kOfferer, service_id);
   }
   NEARBY_LOG(INFO, "Stopped accepting WebRTC connections");
 }
 
 Future<WebRtcSocketWrapper> WebRtc::ListenForWebRtcSocketFuture(
+    const Role& role, const std::string& connection_id,
     Future<rtc::scoped_refptr<webrtc::DataChannelInterface>>
         data_channel_future,
     AcceptedConnectionCallback callback) {
   Future<WebRtcSocketWrapper> socket_future;
-  auto data_channel_runnable = [this, socket_future, data_channel_future,
+  auto data_channel_runnable = [this, role, connection_id, socket_future,
+                                data_channel_future,
                                 callback{std::move(callback)}]() mutable {
     // The overall timeout of creating the socket and data channel is controlled
     // by the caller of this function.
     ExceptionOr<rtc::scoped_refptr<webrtc::DataChannelInterface>> res =
         data_channel_future.Get();
     if (res.ok()) {
-      WebRtcSocketWrapper wrapper = CreateWebRtcSocketWrapper(res.result());
+      WebRtcSocketWrapper wrapper =
+          CreateWebRtcSocketWrapper(role, connection_id, res.result());
       callback.accepted_cb(wrapper);
       {
         MutexLock lock(&mutex_);
-        socket_ = wrapper;
+        ConnectionInfo* connection_info =
+            GetConnectionInfo(role, connection_id);
+        if (connection_info) {
+          connection_info->socket = wrapper;
+        }
       }
       socket_future.Set(wrapper);
     } else {
@@ -219,274 +257,370 @@ Future<WebRtcSocketWrapper> WebRtc::ListenForWebRtcSocketFuture(
 }
 
 WebRtcSocketWrapper WebRtc::CreateWebRtcSocketWrapper(
+    const Role& role, const std::string& connection_id,
     rtc::scoped_refptr<webrtc::DataChannelInterface> data_channel) {
   if (data_channel == nullptr) {
     return WebRtcSocketWrapper();
   }
 
   auto socket = std::make_unique<WebRtcSocket>("WebRtcSocket", data_channel);
-  socket->SetOnSocketClosedListener(
-      {[this]() { OffloadFromSignalingThread([this]() { Disconnect(); }); }});
+  socket->SetOnSocketClosedListener({[this, role, connection_id]() {
+    OffloadFromSignalingThread(
+        [this, role, connection_id]() { Disconnect(role, connection_id); });
+  }});
   return WebRtcSocketWrapper(std::move(socket));
 }
 
-bool WebRtc::InitWebRtcFlow(Role role, const PeerId& self_id,
-                            const LocationHint& location_hint) {
-  role_ = role;
-  self_id_ = self_id;
+bool WebRtc::InitWebRtcFlow(const Role& role, const PeerId& self_id,
+                            const LocationHint& location_hint,
+                            const std::string& connection_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (!connection_info) return false;
+  connection_info->self_id = self_id;
 
-  if (connection_flow_) {
+  if (connection_info->connection_flow) {
     LogAndShutdownSignaling(
+        role, connection_id,
         "Tried to initialize WebRTC without shutting down the previous "
         "connection");
     return false;
   }
 
-  if (signaling_messenger_) {
+  if (connection_info->signaling_messenger) {
     LogAndShutdownSignaling(
+        role, connection_id,
         "Tried to initialize WebRTC without shutting down signaling messenger");
     return false;
   }
+  connection_info->signaling_messenger =
+      medium_.GetSignalingMessenger(self_id.GetId(), location_hint);
+  auto signaling_message_callback = std::bind(
+      [this](ByteArray message, Role role, const std::string& connection_id) {
+        OffloadFromSignalingThread([this, message{std::move(message)},
+                                    role{role},
+                                    connection_id{connection_id}]() {
+          ProcessSignalingMessage(role, connection_id, message);
+        });
+      },
+      std::placeholders::_1, role, connection_id);
 
-  signaling_messenger_ =
-      medium_.GetSignalingMessenger(self_id_.GetId(), location_hint);
-  auto signaling_message_callback = [this](ByteArray message) {
-    OffloadFromSignalingThread([this, message{std::move(message)}]() {
-      ProcessSignalingMessage(message);
-    });
-  };
-
-  if (!signaling_messenger_->IsValid() ||
-      !signaling_messenger_->StartReceivingMessages(
+  if (!connection_info->signaling_messenger->IsValid() ||
+      !connection_info->signaling_messenger->StartReceivingMessages(
           signaling_message_callback)) {
-    DisconnectLocked();
+    LogAndDisconnect(role, connection_id,
+                     "Could not receive from signaling messenger.");
     return false;
   }
 
-  if (role_ == Role::kAnswerer &&
-      !signaling_messenger_->SendMessage(
-          peer_id_.GetId(),
+  if (role == Role::kAnswerer &&
+      !connection_info->signaling_messenger->SendMessage(
+          connection_info->peer_id.GetId(),
           webrtc_frames::EncodeReadyForSignalingPoke(self_id))) {
-    LogAndDisconnect(absl::StrCat("Could not send signaling poke to peer ",
-                                  peer_id_.GetId()));
+    LogAndDisconnect(Role::kAnswerer, connection_info->peer_id.GetId(),
+                     absl::StrCat("Could not send signaling poke to peer ",
+                                  connection_info->peer_id.GetId()));
     return false;
   }
 
-  connection_flow_ = ConnectionFlow::Create(GetLocalIceCandidateListener(),
-                                            GetDataChannelListener(), medium_);
-  if (!connection_flow_) return false;
+  connection_info->connection_flow = ConnectionFlow::Create(
+      GetLocalIceCandidateListener(role, connection_id),
+      GetDataChannelListener(role, connection_id), medium_);
+  if (!connection_info->connection_flow) {
+    LogAndDisconnect(role, connection_id, "Failed to create connection flow");
+    return false;
+  }
 
   return true;
 }
 
 void WebRtc::OnLocalIceCandidate(
+    const Role& role, const std::string& connection_id,
     const webrtc::IceCandidateInterface* local_ice_candidate) {
   ::location::nearby::mediums::IceCandidate ice_candidate =
       webrtc_frames::EncodeIceCandidate(*local_ice_candidate);
 
-  OffloadFromSignalingThread([this, ice_candidate{std::move(ice_candidate)}]() {
+  OffloadFromSignalingThread([this, ice_candidate{std::move(ice_candidate)},
+                              role{role}, connection_id{connection_id}]() {
     MutexLock lock(&mutex_);
-    if (IsSignaling()) {
-      signaling_messenger_->SendMessage(
-          peer_id_.GetId(), webrtc_frames::EncodeIceCandidates(
-                                self_id_, {std::move(ice_candidate)}));
+    ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+    if (IsSignaling(role, connection_id)) {
+      if (connection_info && connection_info->signaling_messenger) {
+        connection_info->signaling_messenger->SendMessage(
+            connection_info->peer_id.GetId(),
+            webrtc_frames::EncodeIceCandidates(connection_info->self_id,
+                                               {std::move(ice_candidate)}));
+      } else {
+        connection_info->pending_local_ice_candidates.push_back(
+            std::move(ice_candidate));
+      }
     } else {
-      pending_local_ice_candidates_.push_back(std::move(ice_candidate));
+      connection_info->pending_local_ice_candidates.push_back(
+          std::move(ice_candidate));
     }
   });
 }
 
-LocalIceCandidateListener WebRtc::GetLocalIceCandidateListener() {
-  return {std::bind(&WebRtc::OnLocalIceCandidate, this, std::placeholders::_1)};
+LocalIceCandidateListener WebRtc::GetLocalIceCandidateListener(
+    const Role& role, const std::string& connection_id) {
+  return {std::bind(&WebRtc::OnLocalIceCandidate, this, role, connection_id,
+                    std::placeholders::_1)};
 }
 
-void WebRtc::OnDataChannelClosed() {
-  OffloadFromSignalingThread([this]() {
+void WebRtc::OnDataChannelClosed(const Role& role,
+                                 const std::string& connection_id) {
+  OffloadFromSignalingThread([this, role, connection_id]() {
     MutexLock lock(&mutex_);
-    LogAndDisconnect("WebRTC data channel closed");
+    LogAndDisconnect(role, connection_id, "WebRTC data channel closed");
   });
 }
 
-void WebRtc::OnDataChannelMessageReceived(const ByteArray& message) {
-  OffloadFromSignalingThread([this, message]() {
-    MutexLock lock(&mutex_);
-    if (!socket_.IsValid()) {
-      LogAndDisconnect("Received a data channel message without a socket");
-      return;
+void WebRtc::OnDataChannelMessageReceived(const Role& role,
+                                          const std::string& connection_id,
+                                          const ByteArray& message) {
+  OffloadFromSignalingThread([this, role, connection_id, message]() {
+    {
+      MutexLock lock(&mutex_);
+      ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+      if (!connection_info) return;
+      if (!connection_info->socket.IsValid()) {
+        LogAndDisconnect(role, connection_id,
+                         "Received a data channel message without a socket");
+        return;
+      }
+      connection_info->socket.NotifyDataChannelMsgReceived(message);
     }
-
-    socket_.NotifyDataChannelMsgReceived(message);
   });
 }
 
-void WebRtc::OnDataChannelBufferedAmountChanged() {
-  OffloadFromSignalingThread([this]() {
-    MutexLock lock(&mutex_);
-    if (!socket_.IsValid()) {
-      LogAndDisconnect("Data channel buffer changed without a socket");
-      return;
+void WebRtc::OnDataChannelBufferedAmountChanged(
+    const Role& role, const std::string& connection_id) {
+  OffloadFromSignalingThread([this, role, connection_id]() {
+    {
+      MutexLock lock(&mutex_);
+      ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+      if (!connection_info) return;
+      if (!connection_info->socket.IsValid()) {
+        LogAndDisconnect(role, connection_id,
+                         "Data channel buffer changed without a socket");
+        return;
+      }
+      connection_info->socket.NotifyDataChannelBufferedAmountChanged();
     }
-
-    socket_.NotifyDataChannelBufferedAmountChanged();
   });
 }
 
-DataChannelListener WebRtc::GetDataChannelListener() {
+DataChannelListener WebRtc::GetDataChannelListener(
+    const Role& role, const std::string& connection_id) {
   return {
-      .data_channel_closed_cb = std::bind(&WebRtc::OnDataChannelClosed, this),
-      .data_channel_message_received_cb = std::bind(
-          &WebRtc::OnDataChannelMessageReceived, this, std::placeholders::_1),
+      .data_channel_closed_cb =
+          std::bind(&WebRtc::OnDataChannelClosed, this, role, connection_id),
+      .data_channel_message_received_cb =
+          std::bind(&WebRtc::OnDataChannelMessageReceived, this, role,
+                    connection_id, std::placeholders::_1),
       .data_channel_buffered_amount_changed_cb =
-          std::bind(&WebRtc::OnDataChannelBufferedAmountChanged, this),
+          std::bind(&WebRtc::OnDataChannelBufferedAmountChanged, this, role,
+                    connection_id),
   };
 }
 
-bool WebRtc::IsSignaling() {
-  return (role_ != Role::kNone && self_id_.IsValid() && peer_id_.IsValid());
+bool WebRtc::IsSignaling(const Role& role, const std::string& connection_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (!connection_info) return false;
+  return (connection_info->self_id.IsValid() &&
+          connection_info->peer_id.IsValid());
 }
 
-void WebRtc::ProcessSignalingMessage(const ByteArray& message) {
+void WebRtc::ProcessSignalingMessage(const Role& role,
+                                     const std::string& connection_id,
+                                     const ByteArray& message) {
   MutexLock lock(&mutex_);
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (!connection_info) return;
 
-  if (!connection_flow_) {
-    LogAndDisconnect("Received WebRTC frame before signaling was started");
+  if (!connection_info->connection_flow) {
+    LogAndDisconnect(role, connection_id,
+                     "Received WebRTC frame before signaling was started");
     return;
   }
 
   location::nearby::mediums::WebRtcSignalingFrame frame;
   if (!frame.ParseFromString(std::string(message))) {
-    LogAndDisconnect("Failed to parse signaling message");
+    LogAndDisconnect(role, connection_id, "Failed to parse signaling message");
     return;
   }
 
   if (!frame.has_sender_id()) {
-    LogAndDisconnect("Invalid WebRTC frame: Sender ID is missing");
+    LogAndDisconnect(role, connection_id,
+                     "Invalid WebRTC frame: Sender ID is missing");
     return;
   }
 
-  if (frame.has_ready_for_signaling_poke() && !peer_id_.IsValid()) {
-    peer_id_ = PeerId(frame.sender_id().id());
+  if (frame.has_ready_for_signaling_poke() &&
+      !connection_info->peer_id.IsValid()) {
+    connection_info->peer_id = PeerId(frame.sender_id().id());
     NEARBY_LOG(INFO, "Peer %s is ready for signaling",
-               peer_id_.GetId().c_str());
+               connection_info->peer_id.GetId().c_str());
   }
 
-  if (!IsSignaling()) {
+  if (!IsSignaling(role, connection_id)) {
     NEARBY_LOG(INFO,
                "Ignoring WebRTC frame: we are not currently listening for "
                "signaling messages");
     return;
   }
 
-  if (frame.sender_id().id() != peer_id_.GetId()) {
+  if (frame.sender_id().id() != connection_info->peer_id.GetId()) {
     NEARBY_LOG(
         INFO, "Ignoring WebRTC frame: we are only listening for another peer.");
     return;
   }
 
   if (frame.has_ready_for_signaling_poke()) {
-    SendOfferAndIceCandidatesToPeer();
+    SendOfferAndIceCandidatesToPeer(connection_id);
   } else if (frame.has_offer()) {
-    connection_flow_->OnOfferReceived(
+    DCHECK(role == Role::kAnswerer);
+    connection_info->connection_flow->OnOfferReceived(
         SessionDescriptionWrapper(webrtc_frames::DecodeOffer(frame).release()));
-    SendAnswerToPeer();
+    SendAnswerToPeer(connection_id);
   } else if (frame.has_answer()) {
-    connection_flow_->OnAnswerReceived(SessionDescriptionWrapper(
-        webrtc_frames::DecodeAnswer(frame).release()));
+    DCHECK(role == Role::kOfferer);
+    connection_info->connection_flow->OnAnswerReceived(
+        SessionDescriptionWrapper(
+            webrtc_frames::DecodeAnswer(frame).release()));
   } else if (frame.has_ice_candidates()) {
-    if (!connection_flow_->OnRemoteIceCandidatesReceived(
+    if (!connection_info->connection_flow->OnRemoteIceCandidatesReceived(
             webrtc_frames::DecodeIceCandidates(frame))) {
-      LogAndDisconnect("Could not add remote ice candidates.");
+      LogAndDisconnect(role, connection_id,
+                       "Could not add remote ice candidates.");
     }
   }
 }
 
-void WebRtc::SendOfferAndIceCandidatesToPeer() {
-  if (pending_local_offer_.Empty()) {
+void WebRtc::SendOfferAndIceCandidatesToPeer(const std::string& service_id) {
+  ConnectionInfo* connection_info =
+      GetConnectionInfo(Role::kOfferer, service_id);
+  if (!connection_info) return;
+  if (connection_info->pending_local_offer.Empty()) {
     LogAndDisconnect(
+        Role::kOfferer, service_id,
         "Unable to send pending offer to remote peer: local offer not set");
     return;
   }
 
-  if (!signaling_messenger_->SendMessage(peer_id_.GetId(),
-                                         pending_local_offer_)) {
-    LogAndDisconnect("Failed to send local offer via signaling messenger");
+  if (!connection_info->signaling_messenger->SendMessage(
+          connection_info->peer_id.GetId(),
+          connection_info->pending_local_offer)) {
+    LogAndDisconnect(Role::kOfferer, service_id,
+                     "Failed to send local offer via signaling messenger");
     return;
   }
-  pending_local_offer_ = ByteArray();
+  connection_info->pending_local_offer = ByteArray();
 
-  if (!pending_local_ice_candidates_.empty()) {
-    signaling_messenger_->SendMessage(
-        peer_id_.GetId(),
+  if (!connection_info->pending_local_ice_candidates.empty()) {
+    connection_info->signaling_messenger->SendMessage(
+        connection_info->peer_id.GetId(),
         webrtc_frames::EncodeIceCandidates(
-            self_id_, std::move(pending_local_ice_candidates_)));
+            connection_info->self_id,
+            std::move(connection_info->pending_local_ice_candidates)));
   }
 }
 
-void WebRtc::SendAnswerToPeer() {
-  SessionDescriptionWrapper answer = connection_flow_->CreateAnswer();
+void WebRtc::SendAnswerToPeer(const std::string& peer_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(Role::kAnswerer, peer_id);
+  if (!connection_info) return;
+  SessionDescriptionWrapper answer =
+      connection_info->connection_flow->CreateAnswer();
   ByteArray answer_message(
-      webrtc_frames::EncodeAnswer(self_id_, answer.GetSdp()));
+      webrtc_frames::EncodeAnswer(connection_info->self_id, answer.GetSdp()));
 
-  if (!SetLocalSessionDescription(std::move(answer))) return;
+  if (!SetLocalSessionDescription(std::move(answer), Role::kAnswerer, peer_id))
+    return;
 
-  if (!signaling_messenger_->SendMessage(peer_id_.GetId(), answer_message)) {
-    LogAndDisconnect("Failed to send local answer via signaling messenger");
+  if (!connection_info->signaling_messenger->SendMessage(
+          connection_info->peer_id.GetId(), answer_message)) {
+    LogAndDisconnect(Role::kAnswerer, peer_id,
+                     "Failed to send local answer via signaling messenger");
     return;
   }
 }
 
-void WebRtc::LogAndDisconnect(const std::string& error_message) {
-  NEARBY_LOG(WARNING, "Disconnecting WebRTC : %s", error_message.c_str());
-  DisconnectLocked();
+void WebRtc::LogAndDisconnect(const Role& role,
+                              const std::string& connection_id,
+                              const std::string& error_message) {
+  NEARBY_LOG(WARNING,
+             "Disconnecting WebRTC role: %d, connection id: %s, msg: %s", role,
+             connection_id.c_str(), error_message.c_str());
+  DisconnectLocked(role, connection_id);
 }
 
-void WebRtc::LogAndShutdownSignaling(const std::string& error_message) {
-  NEARBY_LOG(WARNING, "Stopping WebRTC signaling : %s", error_message.c_str());
-  ShutdownSignaling();
+void WebRtc::LogAndShutdownSignaling(const Role& role,
+                                     const std::string& connection_id,
+                                     const std::string& error_message) {
+  NEARBY_LOG(WARNING, "Stopping WebRTC role: %d, connection id: %s, msg: %s",
+             role, connection_id.c_str(), error_message.c_str());
+  ShutdownSignaling(role, connection_id);
 }
 
-void WebRtc::ShutdownSignaling() {
-  role_ = Role::kNone;
-  self_id_ = PeerId();
-  peer_id_ = PeerId();
-  pending_local_offer_ = ByteArray();
-  pending_local_ice_candidates_.clear();
-
-  if (restart_receive_messages_alarm_.IsValid()) {
-    restart_receive_messages_alarm_.Cancel();
-    restart_receive_messages_alarm_ = CancelableAlarm();
+void WebRtc::ShutdownSignaling(const Role& role,
+                               const std::string& connection_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (!connection_info) {
+    return;
   }
 
-  if (signaling_messenger_) {
-    signaling_messenger_->StopReceivingMessages();
-    signaling_messenger_.reset();
+  connection_info->self_id = PeerId();
+  connection_info->peer_id = PeerId();
+  connection_info->pending_local_offer = ByteArray();
+  connection_info->pending_local_ice_candidates.clear();
+
+  if (connection_info->restart_receive_messages_alarm.IsValid()) {
+    connection_info->restart_receive_messages_alarm.Cancel();
+    connection_info->restart_receive_messages_alarm = CancelableAlarm();
   }
 
-  if (!socket_.IsValid()) ShutdownIceCandidateCollection();
+  if (connection_info->signaling_messenger) {
+    connection_info->signaling_messenger->StopReceivingMessages();
+    connection_info->signaling_messenger.reset();
+  }
+
+  if (!connection_info->socket.IsValid())
+    ShutdownIceCandidateCollection(role, connection_id);
 }
 
-void WebRtc::Disconnect() {
+void WebRtc::Disconnect(const Role& role, const std::string& connection_id) {
   MutexLock lock(&mutex_);
-  DisconnectLocked();
+  DisconnectLocked(role, connection_id);
 }
 
-void WebRtc::DisconnectLocked() {
-  ShutdownSignaling();
-  ShutdownWebRtcSocket();
-  ShutdownIceCandidateCollection();
-}
+void WebRtc::DisconnectLocked(const Role& role,
+                              const std::string& connection_id) {
+  ShutdownSignaling(role, connection_id);
+  ShutdownWebRtcSocket(role, connection_id);
+  ShutdownIceCandidateCollection(role, connection_id);
 
-void WebRtc::ShutdownWebRtcSocket() {
-  if (socket_.IsValid()) {
-    socket_.Close();
-    socket_ = WebRtcSocketWrapper();
+  if (role == Role::kOfferer && accepting_map_.contains(connection_id)) {
+    accepting_map_.erase(connection_id);
+  } else if (role == Role::kAnswerer &&
+             connecting_map_.contains(connection_id)) {
+    connecting_map_.erase(connection_id);
   }
 }
 
-void WebRtc::ShutdownIceCandidateCollection() {
-  if (connection_flow_) {
-    connection_flow_->Close();
-    connection_flow_.reset();
+void WebRtc::ShutdownWebRtcSocket(const Role& role,
+                                  const std::string& connection_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (connection_info && connection_info->socket.IsValid()) {
+    connection_info->socket.Close();
+    connection_info->socket = WebRtcSocketWrapper();
+  }
+}
+
+void WebRtc::ShutdownIceCandidateCollection(const Role& role,
+                                            const std::string& connection_id) {
+  ConnectionInfo* connection_info = GetConnectionInfo(role, connection_id);
+  if (connection_info && connection_info->connection_flow) {
+    connection_info->connection_flow->Close();
+    connection_info->connection_flow.reset();
   }
 }
 
@@ -505,25 +639,49 @@ void WebRtc::RestartReceiveMessages(const LocationHint& location_hint,
   NEARBY_LOG(INFO, "Restarting listening for receiving signaling messages.");
   {
     MutexLock lock(&mutex_);
-    signaling_messenger_->StopReceivingMessages();
+    ConnectionInfo* connection_info =
+        GetConnectionInfo(Role::kOfferer, service_id);
+    if (!connection_info) {
+      NEARBY_LOG(ERROR,
+                 "Can't find connection info in RestartReceiveMessages for %s",
+                 service_id.c_str());
+      return;
+    }
+    connection_info->signaling_messenger->StopReceivingMessages();
 
-    signaling_messenger_ =
-        medium_.GetSignalingMessenger(self_id_.GetId(), location_hint);
+    connection_info->signaling_messenger = medium_.GetSignalingMessenger(
+        connection_info->self_id.GetId(), location_hint);
 
-    auto signaling_message_callback = [this](ByteArray message) {
-      OffloadFromSignalingThread([this, message{std::move(message)}]() {
-        ProcessSignalingMessage(message);
-      });
-    };
+    auto signaling_message_callback = std::bind(
+        [this](ByteArray message, const Role& role,
+               const std::string& connection_id) {
+          OffloadFromSignalingThread([this, message{std::move(message)},
+                                      role{role},
+                                      connection_id{connection_id}]() {
+            ProcessSignalingMessage(role, connection_id, message);
+          });
+        },
+        std::placeholders::_1, Role::kOfferer, service_id);
 
-    if (!signaling_messenger_->IsValid() ||
-        !signaling_messenger_->StartReceivingMessages(
+    if (!connection_info->signaling_messenger->IsValid() ||
+        !connection_info->signaling_messenger->StartReceivingMessages(
             signaling_message_callback)) {
-      DisconnectLocked();
+      DisconnectLocked(Role::kOfferer, service_id);
     }
   }
 }
 
+WebRtc::ConnectionInfo* WebRtc::GetConnectionInfo(
+    const Role& role, const std::string& connection_id) {
+  if (role == Role::kOfferer && accepting_map_.contains(connection_id)) {
+    return &accepting_map_[connection_id];
+  } else if (role == Role::kAnswerer &&
+             connecting_map_.contains(connection_id)) {
+    return &connecting_map_[connection_id];
+  }
+  return nullptr;
+}
+
 }  // namespace mediums
 }  // namespace connections
 }  // namespace nearby

cpp/core/internal/mediums/webrtc.h

@@ -37,6 +37,7 @@
 #include "platform/public/single_thread_executor.h"
 #include "platform/public/webrtc.h"
 #include "location/nearby/mediums/proto/web_rtc_signaling_frames.pb.h"
+#include "absl/container/flat_hash_map.h"
 #include "absl/container/flat_hash_set.h"
 #include "webrtc/api/data_channel_interface.h"
 #include "webrtc/api/jsep.h"
@@ -99,65 +100,102 @@ class WebRtc {
     kAnswerer = 2,
   };
 
-  bool InitWebRtcFlow(Role role, const PeerId& self_id,
-                      const LocationHint& location_hint)
+  struct ConnectionInfo {
+    std::unique_ptr<ConnectionFlow> connection_flow;
+    std::unique_ptr<WebRtcSignalingMessenger> signaling_messenger;
+    WebRtcSocketWrapper socket;
+    CancelableAlarm restart_receive_messages_alarm;
+
+    PeerId self_id;
+    PeerId peer_id;
+    ByteArray pending_local_offer;
+    std::vector<::location::nearby::mediums::IceCandidate>
+        pending_local_ice_candidates;
+  };
+
+  bool InitWebRtcFlow(const Role& role, const PeerId& self_id,
+                      const LocationHint& location_hint,
+                      const std::string& connection_id)
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   Future<WebRtcSocketWrapper> ListenForWebRtcSocketFuture(
+      const Role& role, const std::string& connection_id,
       Future<rtc::scoped_refptr<webrtc::DataChannelInterface>>
           data_channel_future,
       AcceptedConnectionCallback callback);
 
   WebRtcSocketWrapper CreateWebRtcSocketWrapper(
+      const Role& role, const std::string& connection_id,
       rtc::scoped_refptr<webrtc::DataChannelInterface> data_channel);
 
-  LocalIceCandidateListener GetLocalIceCandidateListener();
+  LocalIceCandidateListener GetLocalIceCandidateListener(
+      const Role& role, const std::string& connection_id);
   void OnLocalIceCandidate(
+      const Role& role, const std::string& connection_id,
       const webrtc::IceCandidateInterface* local_ice_candidate);
 
-  DataChannelListener GetDataChannelListener();
-  void OnDataChannelClosed();
-  void OnDataChannelMessageReceived(const ByteArray& message);
-  void OnDataChannelBufferedAmountChanged();
+  DataChannelListener GetDataChannelListener(const Role& role,
+                                             const std::string& connection_id);
+  void OnDataChannelClosed(const Role& role, const std::string& connection_id);
+  void OnDataChannelMessageReceived(const Role& role,
+                                    const std::string& connection_id,
+                                    const ByteArray& message);
+  void OnDataChannelBufferedAmountChanged(const Role& role,
+                                          const std::string& connection_id);
 
   // Runs on @MainThread and |single_thread_executor_|.
-  bool SetLocalSessionDescription(SessionDescriptionWrapper sdp)
+  bool SetLocalSessionDescription(SessionDescriptionWrapper sdp, Role role,
+                                  const std::string& connection_id)
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on |single_thread_executor_|.
-  bool IsSignaling() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  bool IsSignaling(const Role& role, const std::string& connection_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on |single_thread_executor_|.
-  void ProcessSignalingMessage(const ByteArray& message)
+  void ProcessSignalingMessage(const Role& role,
+                               const std::string& connection_id,
+                               const ByteArray& message)
       ABSL_LOCKS_EXCLUDED(mutex_);
 
   // Runs on |single_thread_executor_|.
-  void SendOfferAndIceCandidatesToPeer() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void SendOfferAndIceCandidatesToPeer(const std::string& service_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on |single_thread_executor_|.
-  void SendAnswerToPeer() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void SendAnswerToPeer(const std::string& peer_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on @MainThread and |single_thread_executor_|.
-  void LogAndDisconnect(const std::string& error_message)
+  void LogAndDisconnect(const Role& role, const std::string& connection_id,
+                        const std::string& error_message)
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on @MainThread.
-  void Disconnect() ABSL_LOCKS_EXCLUDED(mutex_);
+  void Disconnect(const Role& role, const std::string& connection_id)
+      ABSL_LOCKS_EXCLUDED(mutex_);
 
   // Runs on @MainThread and |single_thread_executor_|.
-  void DisconnectLocked() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void DisconnectLocked(const Role& role, const std::string& connection_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
-  void LogAndShutdownSignaling(const std::string& error_message)
+  void LogAndShutdownSignaling(const Role& role,
+                               const std::string& connection_id,
+                               const std::string& error_message)
       ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on @MainThread and |single_thread_executor_|.
-  void ShutdownSignaling() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void ShutdownSignaling(const Role& role, const std::string& connection_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on @MainThread and |single_thread_executor_|.
-  void ShutdownWebRtcSocket() ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void ShutdownWebRtcSocket(const Role& role, const std::string& connection_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   // Runs on @MainThread and |single_thread_executor_|.
-  void ShutdownIceCandidateCollection();
+  void ShutdownIceCandidateCollection(const Role& role,
+                                      const std::string& connection_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
 
   void OffloadFromSignalingThread(Runnable runnable);
 
@@ -166,26 +204,27 @@ class WebRtc {
                               const std::string& service_id)
       ABSL_LOCKS_EXCLUDED(mutex_);
 
+  void PrintStatus(const std::string& func);
+
+  ConnectionInfo* GetConnectionInfo(const Role& role,
+                                    const std::string& connection_id)
+      ABSL_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+
   Mutex mutex_;
 
-  Role role_ ABSL_GUARDED_BY(mutex_) = Role::kNone;
-  PeerId self_id_ ABSL_GUARDED_BY(mutex_);
-  PeerId peer_id_ ABSL_GUARDED_BY(mutex_);
-  ByteArray pending_local_offer_ ABSL_GUARDED_BY(mutex_);
-  std::vector<::location::nearby::mediums::IceCandidate>
-      pending_local_ice_candidates_ ABSL_GUARDED_BY(mutex_);
-
   WebRtcMedium medium_;
-  std::unique_ptr<ConnectionFlow> connection_flow_;
-  std::unique_ptr<WebRtcSignalingMessenger> signaling_messenger_
-      ABSL_GUARDED_BY(mutex_);
-  WebRtcSocketWrapper socket_ ABSL_GUARDED_BY(mutex_);
 
   SingleThreadExecutor single_thread_executor_;
 
   // Restarts the signaling messenger for receiving messages.
   ScheduledExecutor restart_receive_messages_executor_;
-  CancelableAlarm restart_receive_messages_alarm_;
+
+  // Use service_id as key for accepting connections.
+  absl::flat_hash_map<std::string, ConnectionInfo> accepting_map_
+      ABSL_GUARDED_BY(mutex_);
+  // Use remote peer_id as key for connecting connections.
+  absl::flat_hash_map<std::string, ConnectionInfo> connecting_map_
+      ABSL_GUARDED_BY(mutex_);
 };
 
 }  // namespace mediums

cpp/core/internal/mediums/webrtc_test.cc

@@ -62,7 +62,8 @@ TEST_F(WebRtcTest, StartAcceptingConnectionTwice) {
   EXPECT_FALSE(webrtc.StartAcceptingConnections(
       service_id, self_id, location_hint,
       {mock_accepted_callback_.AsStdFunction()}));
-  EXPECT_TRUE(webrtc.IsAcceptingConnections(std::string{}));
+  EXPECT_TRUE(webrtc.IsAcceptingConnections(service_id));
+  EXPECT_FALSE(webrtc.IsAcceptingConnections(std::string{}));
 }
 
 // Tests the flow when the device tries to connect but the data channel times
@@ -99,7 +100,7 @@ TEST_F(WebRtcTest, StartAcceptingConnection_ThenConnect) {
       {mock_accepted_callback_.AsStdFunction()}));
   WebRtcSocketWrapper wrapper =
       webrtc.Connect(PeerId("random_peer_id"), location_hint);
-  EXPECT_TRUE(webrtc.IsAcceptingConnections(std::string{}));
+  EXPECT_TRUE(webrtc.IsAcceptingConnections(service_id));
   EXPECT_FALSE(wrapper.IsValid());
   EXPECT_FALSE(webrtc.StartAcceptingConnections(
       service_id, self_id, location_hint,
@@ -122,8 +123,9 @@ TEST_F(WebRtcTest, StartAndStopAcceptingConnections) {
   ASSERT_TRUE(webrtc.StartAcceptingConnections(
       service_id, self_id, location_hint,
       {mock_accepted_callback_.AsStdFunction()}));
+  EXPECT_TRUE(webrtc.IsAcceptingConnections(service_id));
   webrtc.StopAcceptingConnections(service_id);
-  EXPECT_FALSE(webrtc.IsAcceptingConnections(std::string{}));
+  EXPECT_FALSE(webrtc.IsAcceptingConnections(service_id));
 }
 
 // Tests the flow when the device tries to connect to two different peers
@@ -144,11 +146,8 @@ TEST_F(WebRtcTest, ConnectTwice) {
         connected.Set(receiver_socket.IsValid());
       }});
 
-  using MockAcceptedCallback =
-      testing::MockFunction<void(WebRtcSocketWrapper socket)>;
-  testing::StrictMock<MockAcceptedCallback> mock_accepted_callback_;
   device_c.StartAcceptingConnections(service_id, other_id, location_hint,
-                                     {mock_accepted_callback_.AsStdFunction()});
+                                     {[](WebRtcSocketWrapper wrapper) {}});
 
   sender_socket = sender.Connect(self_id, location_hint);
   EXPECT_TRUE(sender_socket.IsValid());
@@ -157,8 +156,11 @@ TEST_F(WebRtcTest, ConnectTwice) {
   ASSERT_TRUE(devices_connected.ok());
   EXPECT_TRUE(devices_connected.result());
 
-  WebRtcSocketWrapper socket = sender.Connect(other_id, location_hint);
-  EXPECT_FALSE(socket.IsValid());
+  WebRtcSocketWrapper socket =
+      sender.Connect(other_id, location_hint);
+  EXPECT_TRUE(socket.IsValid());
+  socket.Close();
+
 
   EXPECT_TRUE(receiver_socket.IsValid());
   EXPECT_TRUE(sender_socket.IsValid());

cpp/core/internal/payload_manager.cc

@@ -16,6 +16,7 @@
 
 #include <algorithm>
 #include <cinttypes>
+#include <limits>
 #include <memory>
 #include <string>
 #include <utility>
@@ -89,8 +90,9 @@ bool PayloadManager::SendPayloadLoop(
 
   // This will block if there is no data to transfer.
   // It will resume when new data arrives, or if Close() is called.
+  int chunk_size = GetOptimalChunkSize(available_endpoint_ids);
   ByteArray next_chunk =
-      pending_payload.GetInternalPayload()->DetachNextChunk();
+      pending_payload.GetInternalPayload()->DetachNextChunk(chunk_size);
   if (shutdown_.Get()) return false;
   // Save chunk size. We'll need it after we move next_chunk.
   auto next_chunk_size = next_chunk.size();
@@ -497,6 +499,15 @@ SingleThreadExecutor* PayloadManager::GetOutgoingPayloadExecutor(
   }
 }
 
+int PayloadManager::GetOptimalChunkSize(EndpointIds endpoint_ids) {
+  int minChunkSize = std::numeric_limits<int>::max();
+  for (const auto& endpoint_id : endpoint_ids) {
+    minChunkSize = std::min(
+        minChunkSize, endpoint_manager_->GetMaxTransmitPacketSize(endpoint_id));
+  }
+  return minChunkSize;
+}
+
 PayloadTransferFrame::PayloadHeader PayloadManager::CreatePayloadHeader(
     const InternalPayload& internal_payload) {
   PayloadTransferFrame::PayloadHeader payload_header;

cpp/core/internal/payload_manager.h

@@ -203,6 +203,8 @@ class PayloadManager : public EndpointManager::FrameProcessor {
   static PayloadProgressInfo::Status PayloadStatusToTransferUpdateStatus(
       proto::connections::PayloadStatus status);
 
+  int GetOptimalChunkSize(EndpointIds endpoint_ids);
+
   PayloadTransferFrame::PayloadHeader CreatePayloadHeader(
       const InternalPayload& payload);
   PayloadTransferFrame::PayloadChunk CreatePayloadChunk(std::int64_t offset,

cpp/platform/api/BUILD

@@ -79,6 +79,7 @@ cc_library(
         "platform.h",
     ],
     visibility = [
+        "//googlemac/iPhone/Shared/Nearby/Connections_v2:__subpackages__",
         "//platform/base:__pkg__",
         "//platform/impl:__subpackages__",
         "//platform/public:__pkg__",

cpp/platform/impl/g3/webrtc.cc

@@ -61,14 +61,14 @@ void WebRtcMedium::CreatePeerConnection(
   webrtc::PeerConnectionInterface::RTCConfiguration rtc_config;
   webrtc::PeerConnectionDependencies dependencies(observer);
 
-  signaling_thread_ = rtc::Thread::Create();
-  signaling_thread_->SetName("signaling_thread", nullptr);
-  RTC_CHECK(signaling_thread_->Start()) << "Failed to start thread";
+  std::unique_ptr<rtc::Thread> signaling_thread = rtc::Thread::Create();
+  signaling_thread->SetName("signaling_thread", nullptr);
+  RTC_CHECK(signaling_thread->Start()) << "Failed to start thread";
 
   webrtc::PeerConnectionFactoryDependencies factory_dependencies;
   factory_dependencies.task_queue_factory =
       webrtc::CreateDefaultTaskQueueFactory();
-  factory_dependencies.signaling_thread = signaling_thread_.get();
+  factory_dependencies.signaling_thread = signaling_thread.release();
 
   callback(webrtc::CreateModularPeerConnectionFactory(
                std::move(factory_dependencies))

cpp/platform/impl/g3/webrtc.h

@@ -65,7 +65,6 @@ class WebRtcMedium : public api::WebRtcMedium {
       const connections::LocationHint& location_hint) override;
 
  private:
-  std::unique_ptr<rtc::Thread> signaling_thread_;
 };
 
 }  // namespace g3