TCPEndpoint_8cpp

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title: src/TCP/TCPEndpoint.cpp summary: TCP socket endpoint for wireless Android Auto communication.

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src/TCP/TCPEndpoint.cpp

TCP socket endpoint for wireless Android Auto communication. More...

Namespaces

Name
aasdk
aasdk::tcp

Detailed Description

TCP socket endpoint for wireless Android Auto communication.

TCPEndpoint wraps a Boost ASIO TCP socket for bidirectional frame exchange with Android device over WiFi network. Designed for wireless deployment where USB cable is unavailable (e.g., embedded infotainment systems, aftermarket head units without USB passthrough).

Operations:

• send(buffer): Async write frame data to socket; resolves when TCP sends
• receive(buffer): Async read frame data from socket; resolves when data ready
• stop(): Close socket cleanly

Scenario: Wireless Android Auto over WiFi connection

• T+0ms: Head unit WiFi connected to device hotspot (192.168.1.2:5037)
• T+50ms: TCPEndpoint created with connected socket
• T+55ms: Messenger calls receive(4) for frame header
• T+55ms: asyncRead queued on socket; waiting for data
• T+100ms: Android App connects from phone; sends protocol greeting
• T+100ms: 4 bytes arrive over TCP; receive promise resolves
• T+105ms: Messenger parses size=256; calls receive(256) for payload
• T+200ms: 256 bytes payload arrives; resolve completes
• T+205ms: Messenger routes message to appropriate channel service

Network characteristics (typical WiFi):

• Latency: 50-200ms depending on WiFi quality and congestion
• Jitter: +/- 100ms variance in frame delivery time
• Potential: Packet loss, TCP retransmission delays
• Advantage: No cable needed; range up to 100ft indoors

Error handling:

• operation_aborted: Endpoint was closed during async operation
• TCP_TRANSFER error: Network failure (connection lost, timeout, etc.)

Thread Safety: All operations dispatched by TCPTransport on single strand. Socket access is not thread-safe; endpoint assumes single-threaded usage.

Source code

// This file is part of aasdk library project.
// Copyright (C) 2018 f1x.studio (Michal Szwaj)
// Copyright (C) 2024 CubeOne (Simon Dean - simon.dean@cubeone.co.uk)
// Copyright (C) 2026 OpenCarDev (Matthew Hilton - matthilton2005@gmail.com)
//
// aasdk is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
//
// aasdk is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with aasdk. If not, see <http://www.gnu.org/licenses/>.

#include <aasdk/TCP/TCPEndpoint.hpp>


namespace aasdk::tcp {

  TCPEndpoint::TCPEndpoint(ITCPWrapper &tcpWrapper, SocketPointer socket)
      : tcpWrapper_(tcpWrapper), socket_(std::move(socket)) {

  }

  void TCPEndpoint::send(common::DataConstBuffer buffer, Promise::Pointer promise) {
    tcpWrapper_.asyncWrite(*socket_, std::move(buffer),
                           std::bind(&TCPEndpoint::asyncOperationHandler,
                                     this->shared_from_this(),
                                     std::placeholders::_1,
                                     std::placeholders::_2,
                                     std::move(promise)));
  }

  void TCPEndpoint::receive(common::DataBuffer buffer, Promise::Pointer promise) {
    tcpWrapper_.asyncRead(*socket_, std::move(buffer),
                          std::bind(&TCPEndpoint::asyncOperationHandler,
                                    this->shared_from_this(),
                                    std::placeholders::_1,
                                    std::placeholders::_2,
                                    std::move(promise)));
  }

  void TCPEndpoint::stop() {
    tcpWrapper_.close(*socket_);
  }

  void TCPEndpoint::asyncOperationHandler(const boost::system::error_code &ec, size_t bytesTransferred,
                                          Promise::Pointer promise) {
    if (!ec) {
      promise->resolve(bytesTransferred);
    } else {
      auto error = ec == boost::asio::error::operation_aborted ? error::Error(error::ErrorCode::OPERATION_ABORTED)
                                                               : error::Error(error::ErrorCode::TCP_TRANSFER,
                                                                              static_cast<uint32_t>(ec.value()));
      promise->reject(error);
    }
  }

}

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Updated on 2026-03-15 at 09:02:41 +0000