https://github.com/inetic/asio-utp
Boost.Asio wrapper over uTorrent's uTP library
https://github.com/inetic/asio-utp
asio cpp cpp14 utp
Last synced: 30 days ago
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Boost.Asio wrapper over uTorrent's uTP library
- Host: GitHub
- URL: https://github.com/inetic/asio-utp
- Owner: inetic
- License: bsl-1.0
- Created: 2018-05-14T20:04:24.000Z (almost 8 years ago)
- Default Branch: master
- Last Pushed: 2021-06-02T16:15:05.000Z (almost 5 years ago)
- Last Synced: 2025-10-20T07:58:40.620Z (5 months ago)
- Topics: asio, cpp, cpp14, utp
- Language: C++
- Homepage:
- Size: 135 KB
- Stars: 27
- Watchers: 2
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE.txt
Awesome Lists containing this project
README
[](https://circleci.com/gh/inetic/asio-utp/tree/master)
# Asio wrapper over the uTorrent's (MIT licensed) uTP library
## Features
Similar API to the TCP sockets in Asio. In particular, the `utp::socket`
implements the [`AsyncReadStream`] and [`AsyncWriteStream`] requirements.
Making it readily usable with Asio's free functions or classes utilizing those
requirements. Such as [`async_read`], [`async_write`], [`ssl::stream`], ...
Also similar to Asio's TCP sockets, `utp::socket`'s `async` API supports
callbacks, futures and coroutines as completion tokens.
The `asio_utp::udp_multiplexer` can be used to perform non uTP sending and
receiving of UDP datagrams.
## Advantages of uTP over TCP
* Multiple uTP connections over one UDP port implies
* better options to do NAT hole-punching
* free hole-punching on certain types of NATs
* fewer open file descriptors
* Low latency
* Yields to TCP
## Clone
`asio-utp` git repository contains `libutp` (the uTorrents uTP library written in C)
as a submodule. Thus one has to clone it recursively:
```
git clone --recursive git@github.com:inetic/asio-utp.git
```
## Build
```
cd asio-utp
mkdir build
cd build
cmake .. -DBOOST_ROOT=
make -j$(nproc)
```
For more detailed instructions, have a look at the `.circleci/config.yml` file.
## Caveats
* An __accepting__ socket may only start sending **after** it received some data
from the __connecting__ socket (likely a consequence of
[this](https://github.com/bittorrent/libutp/issues/74))
* One has to implement their own timeouts and keep-alive packets because
otherwise if the FIN UDP packet gets dropped by the network then the
remaining socket won't get destroyed. Note that there is a mention of
keep-alive packets in `libutp/utp_internals.c`, but those seem to be only
used for preserving holes in NATs (not to indicate whether the other end
is still alive).
* The call to `socket::async_connect` simply executes the underlying
`libutp/utp_connect` function. The latter sends one SYN packet but does not
implement any timeout nor resending of that packet. This needs to be done
explicitly by closing the socket after some timeout and then re-starting
the call to `socket::async_connect`.
## Architecture
```
asio_utp::socket --- asio_utp::socket_impl ---+
\
asio_utp::socket --- asio_utp::socket_impl -----+--- asio_utp::context
/ \
asio_utp::socket --- asio_utp::socket_impl ---+ \
\
+----------- asio_utp::udp_multiplexer_impl
asio_utp::udp_multiplexer ---+ / \
\ / \
asio_utp::udp_multiplexer -----+---+ asio::udp::socket
/
asio_utp::udp_multiplexer ---+
```
## TODO
* Handle ICMP messages
* Thread safety
[`AsyncReadStream`]: https://www.boost.org/doc/libs/1_69_0/doc/html/boost_asio/reference/AsyncReadStream.html
[`AsyncWriteStream`]: https://www.boost.org/doc/libs/1_69_0/doc/html/boost_asio/reference/AsyncWriteStream.html
[`async_read`]: https://www.boost.org/doc/libs/1_69_0/doc/html/boost_asio/reference/async_read.html
[`async_write`]: https://www.boost.org/doc/libs/1_69_0/doc/html/boost_asio/reference/async_write.html
[`ssl::stream`]: https://www.boost.org/doc/libs/1_69_0/doc/html/boost_asio/reference/ssl__stream.html
[API]: https://github.com/inetic/asio-utp/blob/master/include/asio_utp/socket.hpp#L15