react-native-tcp-socket

React Native TCP socket API for Android, iOS & macOS with SSL/TLS support. It allows you to create TCP client and server sockets, imitating Node's net and Node's tls API functionalities (check the available API for more information).

Table of Contents

• Getting started
  • Overriding net
  • Overriding tls
  • Using React Native >= 0.60
  • Self-Signed SSL (only available for React Native > 0.60)
  • Using React Native < 0.60
• React Native Compatibility
• Usage
  • Client example
  • Server example
  • TLS Client example
  • TLS Server example
• API
  • net
    • Socket
    • Server
  • tls
    • TLSSocket
    • TLSServer
• Maintainers
• Acknowledgments
• License

Getting started

Install the library using either Yarn:

yarn add react-native-tcp-socket

or npm:

npm install --save react-native-tcp-socket

Overriding net

Since react-native-tcp-socket offers the same API as Node's net, in case you want to import this module as net or use require('net') in your JavaScript, you must add the following lines to your package.json file.

{
  "react-native": {
    "net": "react-native-tcp-socket"
  }
}

In addition, in order to obtain the TS types (or autocompletion) provided by this module, you must also add the following to your custom declarations file.

...
declare module 'net' {
    import TcpSockets from 'react-native-tcp-socket';
    export = TcpSockets;
}

If you want to avoid duplicated net types, make sure not to use the default node_modules/@types in your tsconfig.json "typeRoots" property.

Check the example app provided for a working example.

Overriding tls

The same applies to tls module. However, you should be aware of the following:

• The Server class exported by default is non-TLS. In order to use the TLS server, you must use the TLSServer class. You may override the default Server class (tls.Server = tls.TLSServer). The same goes with the createServer() and connect(). In order to use the TLS methods, you must use the createTLSServer() and connectTLS() methods respectively. You may override the default methods (tls.createServer = tls.createTLSServer and tls.connect = tls.connectTLS).
• Node's tls module requires the keys and certificates to be provided as a string. However, the react-native-tcp-socket module requires them to be imported with require().

In addition, in order to obtain the TS types (or autocompletion) provided by this module, you must also add the following to your custom declarations file.

...
declare module 'tls' {
    import TcpSockets from 'react-native-tcp-socket';
    export const Server = TcpSockets.TLSServer;
    export const TLSSocket = TcpSockets.TLSSocket;
    export const connect = TcpSockets.connectTLS;
    export const createServer = TcpSockets.createTLSServer;
}

Check the example app provided for a working example.

Using React Native >= 0.60

Linking the package manually is not required anymore with Autolinking.

• iOS Platform:

  $ cd ios && pod install && cd .. # CocoaPods on iOS needs this extra step

• Android Platform:

  Modify your android/build.gradle configuration to match minSdkVersion = 21:

  buildscript {
    ext {
      ...
      minSdkVersion = 21
      ...
    }
  

Self-Signed SSL (only available for React Native > 0.60)

In order to generate the required files (keys and certificates) for self-signed SSL, you can use the following command:

openssl genrsa -out server-key.pem 4096
openssl req -new -key server-key.pem -out server-csr.pem
openssl x509 -req -in server-csr.pem -signkey server-key.pem -out server-cert.pem
openssl pkcs12 -export -out server-keystore.p12 -inkey server-key.pem -in server-cert.pem

Note: The server-keystore.p12 must not have a password.

You will need a metro.config.js file in order to use a self-signed SSL certificate. You should already have this file in your root project directory, but if you don't, create it. Inside a module.exports object, create a key called resolver with another object called assetExts. The value of assetExts should be an array of the resource file extensions you want to support.

If you want to be able to use .pem and .p12 files (plus all the already supported files), your metro.config.js should look like this:

const {getDefaultConfig} = require('metro-config');
const defaultConfig = getDefaultConfig.getDefaultValues(__dirname);

module.exports = {
  resolver: {
    assetExts: [...defaultConfig.resolver.assetExts, 'pem', 'p12'],
  },
  // ...
};

Using React Native < 0.60

You then need to link the native parts of the library for the platforms you are using. The easiest way to link the library is using the CLI tool by running this command from the root of your project:

$ react-native link react-native-tcp-socket

If you can't or don't want to use the CLI tool, you can also manually link the library using the instructions below (click on the arrow to show them):

Manually link the library on iOS

1. In XCode, in the project navigator, right click Libraries ➜ Add Files to [your project's name]
2. Go to node_modules ➜ react-native-tcp-socket and add TcpSockets.xcodeproj
3. In XCode, in the project navigator, select your project. Add libTcpSockets.a to your project's Build Phases ➜ Link Binary With Libraries
4. Run your project (Cmd+R)<

Manually link the library on Android

1. Open up android/app/src/main/java/[...]/MainApplication.java

• Add import com.asterinet.react.tcpsocket.TcpSocketPackage; to the imports at the top of the file
• Add new TcpSocketPackage() to the list returned by the getPackages() method

2. Append the following lines to android/settings.gradle:

   include ':react-native-tcp-socket'
   project(':react-native-tcp-socket').projectDir = new File(rootProject.projectDir, 	'../node_modules/react-native-tcp-socket/android')
   

3. Insert the following lines inside the dependencies block in android/app/build.gradle:

     implementation project(':react-native-tcp-socket')
   

React Native Compatibility

To use this library you need to ensure you are using the correct version of React Native. If you are using a version of React Native that is lower than 0.60 you will need to upgrade before attempting to use the latest version.

react-native-tcp-socket version	Required React Native Version
6.X.X, 5.X.X, 4.X.X, 3.X.X	>= 0.60.0
1.4.0	>= Unknown

Usage

Import the library:

import TcpSocket from 'react-native-tcp-socket';
// const net = require('react-native-tcp-socket');
// const tls = require('react-native-tcp-socket');

Client example

const options = {
  port: port,
  host: '127.0.0.1',
  localAddress: '127.0.0.1',
  reuseAddress: true,
  // localPort: 20000,
  // interface: "wifi",
};

// Create socket
const client = TcpSocket.createConnection(options, () => {
  // Write on the socket
  client.write('Hello server!');

  // Close socket
  client.destroy();
});

client.on('data', function(data) {
  console.log('message was received', data);
});

client.on('error', function(error) {
  console.log(error);
});

client.on('close', function(){
  console.log('Connection closed!');
});

Server example

const server = TcpSocket.createServer(function(socket) {
  socket.on('data', (data) => {
    socket.write('Echo server ' + data);
  });

  socket.on('error', (error) => {
    console.log('An error ocurred with client socket ', error);
  });

  socket.on('close', (error) => {
    console.log('Closed connection with ', socket.address());
  });
}).listen({ port: 12345, host: '0.0.0.0' });

server.on('error', (error) => {
  console.log('An error ocurred with the server', error);
});

server.on('close', () => {
  console.log('Server closed connection');
});

TLS Client example

const options = {
  port: port,
  host: '127.0.0.1',
  localAddress: '127.0.0.1',
  reuseAddress: true,
  // localPort: 20000,
  // interface: "wifi",
  ca: require('server-cert.pem'),
};

// Create socket
const client = TcpSocket.connectTLS(options, () => {
  // Write on the socket
  client.write('Hello server!');

  // Close socket
  client.destroy();
});

client.on('data', function(data) {
  console.log('message was received', data);
});

client.on('error', function(error) {
  console.log(error);
});

client.on('close', function(){
  console.log('Connection closed!');
});

TLS Server example

const options = {
  keystore: require('server-keystore.p12'),
};


const server = TcpSocket.createTLSServer(options, function(socket) {
  socket.on('data', (data) => {
    socket.write('Echo server ' + data);
  });

  socket.on('error', (error) => {
    console.log('An error ocurred with SSL client socket ', error);
  });

  socket.on('close', (error) => {
    console.log('SSL closed connection with ', socket.address());
  });
}).listen({ port: 12345, host: '0.0.0.0' });

server.on('error', (error) => {
  console.log('An error ocurred with the server', error);
});

server.on('close', () => {
  console.log('Server closed connection');
});

Note: In order to use self-signed certificates make sure to update your metro.config.js configuration.

API

net

Here are listed all methods implemented in react-native-tcp-socket that imitate Node's net API, their functionalities are equivalent to those provided by Node's net (more info on #41). However, the methods whose interface differs from Node are marked in bold.

• net.connect(options[, callback])
• net.createConnection(options[, callback])
• net.createServer(connectionListener)
• net.isIP(input)
• net.isIPv4(input)
• net.isIPv6(input)

Socket

• Methods:
  • address()
  • destroy([error])
  • end([data][, encoding][, callback])
  • setEncoding([encoding])
  • setKeepAlive([enable][, initialDelay]) - initialDelay is ignored
  • setNoDelay([noDelay])
  • setTimeout(timeout[, callback])
  • write(data[, encoding][, callback])
  • pause()
  • ref() - Will not have any effect
  • resume()
  • unref() - Will not have any effect
• Properties:
  • Inherited from Stream.Writable:
    • writableNeedDrain
  • bytesRead
  • bytesWritten
  • connecting
  • destroyed
  • localAddress
  • localPort
  • remoteAddress
  • remoteFamily
  • remotePort
  • pending
  • timeout
  • readyState
• Events:
  • Inherited from Stream.Readable:
    • 'pause'
    • 'resume'
  • 'close'
  • 'connect'
  • 'data'
  • 'drain'
  • 'error'
  • 'timeout'

net.createConnection()

net.createConnection(options[, callback]) creates a TCP connection using the given options. The options parameter must be an object with the following properties:

Property	Type	iOS/macOS	Android	Description
port	<number>	✅	✅	Required. Port the socket should connect to.
host	<string>	✅	✅	Host the socket should connect to. IP address in IPv4 format or 'localhost'. Default: 'localhost'.
timeout	<number>	✅	✅	If set, will be used to call setTimeout(timeout) after the socket is created, but before it starts the connection.
localAddress	<string>	✅	✅	Local address the socket should connect from. If not specified, the OS will decide. It is highly recommended to specify a localAddress to prevent overload errors and improve performance.
localPort	<number>	✅	✅	Local port the socket should connect from. If not specified, the OS will decide.
interface	<string>	❌	✅	Interface the socket should connect from. If not specified, it will use the current active connection. The options are: 'wifi', 'ethernet', 'cellular'.
reuseAddress	<boolean>	❌	✅	Enable/disable the reuseAddress socket option. Default: true.

Note: The platforms marked as ❌ use the default value.

Server

• Methods:
  • address()
  • listen(options[, callback])
  • close([callback])
  • getConnections(callback)
• Properties:
  • listening
• Events:
  • 'close'
  • 'connection'
  • 'error'
  • 'listening'

Server.listen()

Server.listen(options[, callback]) creates a TCP server socket using the given options. The options parameter must be an object with the following properties:

Property	Type	iOS/macOS	Android	Description
port	<number>	✅	✅	Required. Port the socket should listen to.
host	<string>	✅	✅	Host the socket should listen to. IP address in IPv4 format or 'localhost'. Default: '0.0.0.0'.
reuseAddress	<boolean>	❌	✅	Enable/disable the reuseAddress socket option. Default: true.

Note: The platforms marked as ❌ use the default value.

tls

Here are listed all methods implemented in react-native-tcp-socket that imitate Node's tls API, their functionalities are equivalent to those provided by Node's tls. However, the methods whose interface differs from Node are marked in bold.

• tls.connectTLS(options[, callback])
• tls.createTLSServer([options][, secureConnectionListener])

TLSSocket

• Methods:
  • All methods from Socket
• Properties:
  • All properties from Socket
• Events:
  • All events from Socket
  • 'secureConnect'

tls.connectTLS()

tls.connectTLS(options[, callback]) creates a TLS socket connection using the given options. The options parameter must be an object with the following properties:

Property	Type	iOS/macOS	Android	Description
ca	<import>	✅	✅	CA file (.pem format) to trust. If null, it will use the device's default SSL trusted list. Useful for self-signed certificates. Check the documentation for generating such file. Default: null.
...	<any>	✅	✅	Any other socket.connect() options not already listed.

TLSServer

Note: The TLS server is named Server in Node's tls, but it is named TLSServer in react-native-tcp-socket in order to avoid confusion with the Server class.

• Methods:
  • All methods from Server
  • setSecureContext(options)
• Properties:
  • All properties from Server
• Events:
  • All events from Server
  • 'secureConnection'

tls.createTLSServer()

tls.createTLSServer([options][, secureConnectionListener]) creates a new tls.TLSServer. The secureConnectionListener, if provided, is automatically set as a listener for the 'secureConnection' event. The options parameter must be an object with the following properties:

Property	Type	iOS/macOS	Android	Description
keystore	<import>	✅	✅	Required. Key store in PKCS#12 format with the server certificate and private key. Check the documentation for generating such file.

Maintainers

• Rapsssito

Acknowledgments

• iOS part originally forked from @aprock react-native-tcp
• react-native-udp

License

The library is released under the MIT license. For more information see LICENSE.