aos/network/web_proxy.cc

#include "aos/network/web_proxy.h"

#include "aos/flatbuffer_merge.h"
#include "aos/network/connect_generated.h"
#include "aos/network/web_proxy_generated.h"
#include "aos/network/web_proxy_utils.h"
#include "api/create_peerconnection_factory.h"
#include "glog/logging.h"

namespace aos {
namespace web_proxy {

namespace {
// Based on webrtc examples. In our controlled environment we expect setting sdp
// to always succeed, and we can't do anything about a failure, so just ignore
// everything.
class DummySetSessionDescriptionObserver
    : public webrtc::SetSessionDescriptionObserver {
 public:
  static DummySetSessionDescriptionObserver *Create() {
    return new rtc::RefCountedObject<DummySetSessionDescriptionObserver>();
  }
  virtual void OnSuccess() {}
  virtual void OnFailure(webrtc::RTCError error) {}
};

}  // namespace

WebsocketHandler::WebsocketHandler(
    ::seasocks::Server *server,
    const std::vector<std::unique_ptr<Subscriber>> &subscribers,
    const aos::FlatbufferDetachedBuffer<aos::Configuration> &config)
    : server_(server), subscribers_(subscribers), config_(config) {}

void WebsocketHandler::onConnect(::seasocks::WebSocket *sock) {
  std::unique_ptr<Connection> conn =
      std::make_unique<Connection>(sock, server_, subscribers_, config_);
  connections_.insert({sock, std::move(conn)});
}

void WebsocketHandler::onData(::seasocks::WebSocket *sock, const uint8_t *data,
                              size_t size) {
  connections_[sock]->HandleWebSocketData(data, size);
}

void WebsocketHandler::onDisconnect(::seasocks::WebSocket *sock) {
  connections_.erase(sock);
}

void Subscriber::RunIteration() {
  if (channels_.empty()) {
    return;
  }

  fetcher_->Fetch();
  VLOG(2) << "Sending a message with " << GetPacketCount(fetcher_->context())
          << "packets";
  for (int packet_index = 0; packet_index < GetPacketCount(fetcher_->context());
       ++packet_index) {
    flatbuffers::Offset<MessageHeader> message =
        PackMessage(&fbb_, fetcher_->context(), channel_index_, packet_index);
    fbb_.Finish(message);

    const flatbuffers::DetachedBuffer buffer = fbb_.Release();

    webrtc::DataBuffer data_buffer(
        rtc::CopyOnWriteBuffer(buffer.data(), buffer.size()),
        true /* binary array */);
    for (auto conn : channels_) {
      conn->Send(data_buffer);
    }
  }
}

bool Subscriber::Compare(const Channel *channel) const {
  return channel->name()->string_view() ==
             fetcher_->channel()->name()->string_view() &&
         channel->type()->string_view() ==
             fetcher_->channel()->type()->string_view();
}

Connection::Connection(
    ::seasocks::WebSocket *sock, ::seasocks::Server *server,
    const std::vector<std::unique_ptr<Subscriber>> &subscribers,
    const aos::FlatbufferDetachedBuffer<aos::Configuration> &config)
    : sock_(sock),
      server_(server),
      subscribers_(subscribers),
      config_(config) {}

// Function called for web socket data. Parses the flatbuffer and handles it
// appropriately.
void Connection::HandleWebSocketData(const uint8_t *data, size_t size) {
  const WebSocketMessage *message =
      flatbuffers::GetRoot<WebSocketMessage>(data);
  switch (message->payload_type()) {
    case Payload::WebSocketSdp: {
      const WebSocketSdp *offer = message->payload_as_WebSocketSdp();
      if (offer->type() != SdpType::OFFER) {
        LOG(WARNING) << "Got the wrong sdp type from client";
        break;
      }
      const flatbuffers::String *sdp = offer->payload();
      webrtc::SdpParseError error;
      std::unique_ptr<webrtc::SessionDescriptionInterface> desc =
          CreateSessionDescription(webrtc::SdpType::kOffer, sdp->str(), &error);
      if (!desc) {
        LOG(WARNING) << "Failed to parse sdp description: "
                     << error.description;
        // TODO(alex): send a message back to browser for failure.
        break;
      }

      // We can only start creating the PeerConnection once we have something to
      // give it, so we wait until we get an offer before starting.
      webrtc::PeerConnectionInterface::RTCConfiguration config;
      config.sdp_semantics = webrtc::SdpSemantics::kUnifiedPlan;
      config.enable_dtls_srtp = true;

      std::unique_ptr<rtc::Thread> signaling_thread = rtc::Thread::Create();
      signaling_thread->SetName("signaling_thread", nullptr);
      signaling_thread->Start();

      webrtc::PeerConnectionFactoryDependencies factory_deps;
      factory_deps.signaling_thread = signaling_thread.release();
      rtc::scoped_refptr<webrtc::PeerConnectionFactoryInterface> factory =
          CreateModularPeerConnectionFactory(std::move(factory_deps));

      peer_connection_ =
          factory->CreatePeerConnection(config, nullptr, nullptr, this);

      peer_connection_->SetRemoteDescription(
          DummySetSessionDescriptionObserver::Create(), desc.release());

      peer_connection_->CreateAnswer(
          this, webrtc::PeerConnectionInterface::RTCOfferAnswerOptions());
      break;
    }
    case Payload::WebSocketIce: {
      const WebSocketIce *ice = message->payload_as_WebSocketIce();
      std::string candidate = ice->candidate()->str();
      std::string sdpMid = ice->sdpMid()->str();
      int sdpMLineIndex = ice->sdpMLineIndex();
      webrtc::SdpParseError error;
      webrtc::IceCandidateInterface *ice_candidate =
          webrtc::CreateIceCandidate(sdpMid, sdpMLineIndex, candidate, &error);
      if (!ice_candidate) {
        LOG(WARNING) << "Failed to parse ice candidate: " << error.description;
        // TODO(alex): send a message back to browser for failure.
        break;
      }
      peer_connection_->AddIceCandidate(ice_candidate);
      break;
    }
    default: { break; }
  }
}

void Connection::Send(const ::flatbuffers::DetachedBuffer &buffer) const {
  webrtc::DataBuffer data_buffer(
      rtc::CopyOnWriteBuffer(buffer.data(), buffer.size()),
      true /* binary array */);
  VLOG(2) << "Sending " << buffer.size() << "bytes to a client";
  data_channel_->Send(data_buffer);
}

void Connection::OnDataChannel(
    rtc::scoped_refptr<webrtc::DataChannelInterface> channel) {
  data_channel_ = channel;
  data_channel_->RegisterObserver(this);
}

void Connection::OnIceCandidate(
    const webrtc::IceCandidateInterface *candidate) {
  flatbuffers::FlatBufferBuilder fbb(512);
  std::string ice_string;
  candidate->ToString(&ice_string);

  flatbuffers::Offset<WebSocketIce> ice_fb = CreateWebSocketIceDirect(
      fbb, ice_string.c_str(), candidate->sdp_mid().c_str(),
      candidate->sdp_mline_index());
  flatbuffers::Offset<WebSocketMessage> ice_message =
      CreateWebSocketMessage(fbb, Payload::WebSocketIce, ice_fb.Union());
  fbb.Finish(ice_message);

  server_->execute(std::make_shared<UpdateData>(sock_, fbb.Release()));
}

// This is the callback for creating an sdp. We have to manually assign it
// locally and send it to the client.
void Connection::OnSuccess(webrtc::SessionDescriptionInterface *desc) {
  peer_connection_->SetLocalDescription(
      DummySetSessionDescriptionObserver::Create(), desc);
  flatbuffers::FlatBufferBuilder fbb(512);
  std::string answer_string;
  desc->ToString(&answer_string);
  flatbuffers::Offset<WebSocketSdp> sdp_fb =
      CreateWebSocketSdpDirect(fbb, SdpType::ANSWER, answer_string.c_str());
  flatbuffers::Offset<WebSocketMessage> answer_message =
      CreateWebSocketMessage(fbb, Payload::WebSocketSdp, sdp_fb.Union());
  fbb.Finish(answer_message);

  server_->execute(std::make_shared<UpdateData>(sock_, fbb.Release()));
}

// Wait until the data channel is ready for data before sending the config.
void Connection::OnStateChange() {
  if (peer_connection_.get() != nullptr &&
      data_channel_->state() == webrtc::DataChannelInterface::kOpen) {
    Send(config_.buffer());
  }
}

// Handle DataChannel messages. Subscribe to each listener that matches the
// subscribe message
void Connection::OnMessage(const webrtc::DataBuffer &buffer) {
  const message_bridge::Connect *message =
      flatbuffers::GetRoot<message_bridge::Connect>(buffer.data.data());
  VLOG(2) << "Got a connect message " << aos::FlatbufferToJson(message);
  for (auto &subscriber : subscribers_) {
    // Make sure the subscriber is for a channel on this node.
    if (subscriber.get() == nullptr) {
      VLOG(2) << ": Null subscriber";
      continue;
    }
    bool found_match = false;
    for (auto channel : *message->channels_to_transfer()) {
      if (subscriber->Compare(channel)) {
        int index = subscriber->index();
        auto it = channels_.find(index);
        if (it == channels_.end()) {
          auto pair = channels_.insert(
              {index, peer_connection_->CreateDataChannel(
                          channel->name()->str() + "/" + channel->type()->str(),
                          nullptr)});
          it = pair.first;
        }
        subscriber->AddListener(it->second);

        VLOG(1) << "Subscribe to: " << channel->type()->str();
        found_match = true;
        break;
      }
    }
    if (!found_match) {
      int index = subscriber->index();
      auto it = channels_.find(index);
      subscriber->RemoveListener(it->second);
    }
  }
}

}  // namespace web_proxy
}  // namespace aos