# js-libp2p-tcp

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> Node.js implementation of the TCP module that libp2p uses, which implements the [interface-connection](https://github.com/libp2p/interface-connection) interface for dial/listen.

`libp2p-tcp` in Node.js is a very thin shim that adds support for dialing to a `multiaddr`. This small shim will enable libp2p to use other different transports.

**Note:** This module uses [pull-streams](https://pull-stream.github.io) for all stream based interfaces.

## Table of Contents

- [Install](#install)
  - [npm](#npm)
- [Usage](#usage)
  - [Example](#example)
  - [This module uses `pull-streams`](#this-module-uses-pull-streams)
    - [Converting `pull-streams` to Node.js Streams](#converting-pull-streams-to-nodejs-streams)
- [API](#api)
- [Contribute](#contribute)
- [License](#license)

## Install

### npm

```sh
> npm i libp2p-tcp
```

## Usage

### Example

```js
const TCP = require('libp2p-tcp')
const multiaddr = require('multiaddr')
const pull = require('pull-stream')

const mh1 = multiaddr('/ip4/127.0.0.1/tcp/9090')
const mh2 = multiaddr('/ip6/::/tcp/9092')

const tcp = new TCP()

const listener = tcp.createListener(mh1, (socket) => {
  console.log('new connection opened')
  pull(
    pull.values(['hello']),
    socket
  )
})

listener.listen(() => {
  console.log('listening')

  pull(
    tcp.dial(mh1),
    pull.log,
    pull.onEnd(() => {
      tcp.close()
    })
  )
})
```

Outputs:

```sh
listening
new connection opened
hello
```

### This module uses `pull-streams`

We expose a streaming interface based on `pull-streams`, rather then on the Node.js core streams implementation (aka Node.js streams). `pull-streams` offers us a better mechanism for error handling and flow control guarantees. If you would like to know more about why we did this, see the discussion at this [issue](https://github.com/ipfs/js-ipfs/issues/362).

You can learn more about pull-streams at:

- [The history of Node.js streams, nodebp April 2014](https://www.youtube.com/watch?v=g5ewQEuXjsQ)
- [The history of streams, 2016](http://dominictarr.com/post/145135293917/history-of-streams)
- [pull-streams, the simple streaming primitive](http://dominictarr.com/post/149248845122/pull-streams-pull-streams-are-a-very-simple)
- [pull-streams documentation](https://pull-stream.github.io/)

#### Converting `pull-streams` to Node.js Streams

If you are a Node.js streams user, you can convert a pull-stream to a Node.js stream using the module [`pull-stream-to-stream`](https://github.com/dominictarr/pull-stream-to-stream), giving you an instance of a Node.js stream that is linked to the pull-stream. For example:

```js
const pullToStream = require('pull-stream-to-stream')

const nodeStreamInstance = pullToStream(pullStreamInstance)
// nodeStreamInstance is an instance of a Node.js Stream
```

To learn more about this utility, visit https://pull-stream.github.io/#pull-stream-to-stream.

## API

[![](https://raw.githubusercontent.com/libp2p/interface-transport/master/img/badge.png)](https://github.com/libp2p/interface-transport)

`libp2p-tcp` accepts TCP addresses both IPFS and non IPFS encapsulated addresses, i.e:

`/ip4/127.0.0.1/tcp/4001`
`/ip4/127.0.0.1/tcp/4001/ipfs/QmHash`

Both for dialing and listening.

## Contribute

Contributions are welcome! The libp2p implementation in JavaScript is a work in progress. As such, there's a few things you can do right now to help out:

- [Check out the existing issues](//github.com/libp2p/js-libp2p-tcp/issues).
- **Perform code reviews**.
- **Add tests**. There can never be enough tests.

Please be aware that all interactions related to libp2p are subject to the IPFS [Code of Conduct](https://github.com/ipfs/community/blob/master/code-of-conduct.md).

Small note: If editing the README, please conform to the [standard-readme](https://github.com/RichardLitt/standard-readme) specification.

## License

[MIT](LICENSE) © 2015-2016 David Dias