hxmmxh / atp

A transmission protocol implementation based on UDP, inspired by libutp

ATP

ATP is a message-oriented reliable transport protocol implementation.

Overview

1. ATP provides reliable transportation of data as well as a series of TCP's features.
2. ATP has a small sized head.
3. ATP allows time critical data transmission by urgent mechanism and clock drift probing.
4. ATP allows multiple connections established over the same port.
5. ATP has a lightweight connecting/disconnecting mechanism. You can "fork" an established connection in ATP without extra 3-way handshake. You will endure shorter TIME_WAIT stage than TCP.
6. ATP provides a framework as well as a service.

Build

Requirements

1. C++17 standard(e.g. g++7.2)

Build

Make the project by command

make lib

Run test on demos by command

make run_test

APIs

All APIs are available in /src/atp.h, and is compatible with C89

ATP as a framework(ASAF)

When ATP is used as a framework, it provides with a flexible underlying control. In this case, You must handle incoming UDP packets and maintain a timer outside the ATP framework. You must interact with the ATP context through two APIs:

1. atp_process_udp When there's an incoming UDP packet, you must inform ATP context to parse the raw UDP packet by calling atp_process_udp, the context will then dispatch the packets to correct ATP sockets.
2. atp_timer_event You must also maintain a timer, and call atp_timer_event to generate timer signals for the context.

ASAF is not thread safe.

Demos

Most of these demos use healper atp_standalone_ APIs provided in /src/atp_standalone.h. These APIs help you from coding the connect/disconnect procedure yourself.

You can build all following tests by

make demos

1. sendfile/recvfile

   The demo includes two separated programs: the sender and the receiver. A File will be sent from the sender to the receiver. In this demo, both sides set their UDP Socket to be nonblock, because there will be no multi-threading or multiplexing. You can set loss rate by modifying function simulate_packet_loss_sendto in /src/atp_callback.cpp.

   Build this demo by

    make test TARGET=demo_file
   

2. send/recv

   This demo is similar to sendfile/recvfile, instead of sending file, send/recv use stdin/stdout now. You can run with argument -s to simulate a ATPPacket by commands with certain format. This demo provides a convenient test method. Build this demo by

    make test TARGET=demo_cmd
   

3. send_poll

   This demo implements the sendfile's part with poll.

   Build this demo by

    make test TARGET=demo_poll
   

4. send_aio

   This demo implements the sendfile's part with aio.

   Build this demo by

    make test TARGET=send_aio
   

ATP as a service

Demos

Docs

/docs/brief.md

License

The whole project is opened under GNU GENERAL PUBLIC LICENSE Version 2.

                    GNU GENERAL PUBLIC LICENSE
                       Version 2, June 1991

Calvin Neo
Copyright (C) 2017  Calvin Neo

This program 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 2 of the License, or
(at your option) any later version.

This program 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 this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.