Simple TCP and TLS classes for Node.js
Promise (async/await) based TCP and TLS client and server for node.js.
Write TCP and TLS clients and servers without the need to deal with streams and callbacks.
Install
npm install node-tcpImport classes:
import { NetConn, NetService } from "node-tcp";or
const { NetConn, NetService } = require("node-tcp");TCP/TLS Client
Use NetConn.connectToHost to connect to a tcp/tls host and obtain the connection object. Options are the options sent to net.connect or tls.connect
TCP Client
// Connect to HTTP server (TCP)
const options = { port: 80, host: 'www.google.com', servername: 'www.google.com' }
const conn = await NetConn.connectToHost(options, false);
console.log(`Connected to ${options.host}:${options.port} using TCP`);
// Write a simple HTTP request
await conn.writeBuffer(Buffer.from('GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n', 'utf8'));
console.log(`Sent data`);
// Read response
let data = await conn.readBuffer(undefined);
console.log(`Received data: ${data.length} bytes`);
const html = data.toString('utf8');
console.log(html);
// Close connection
await conn.end(); TLS Client
// Connect to Google HTTPS (TLS)
const options2 = { port: 443, host: 'www.google.com', servername: 'www.google.com' }
const conn2 = await NetConn.connectToHost(options2, true);
console.log(`Connected to ${options2.host}:${options2.port} using TLS`);
// Write a simple HTTP request
await conn2.writeBuffer(Buffer.from('GET / HTTP/1.1\r\nHost: www.google.com\r\n\r\n', 'utf8'));
console.log(`Sent data`);
// Read response
let data2 = await conn.readBuffer(undefined);
console.log(`Received data: ${data2.length} bytes`);
const html2 = data2.toString('utf8');
console.log(html2);
// Close connection
await conn2.end();Read and Write Data
You can read and write data in various data types:
// Read/write binary buffer of 1024 bytes
const buffer = await conn.readBuffer(1024);
await conn.writeBuffer(buffer);
// Read/write 32 bit integer
const num1 = await conn.readInt();
await conn.writeInt(num1);
// Read/write float
const num2 = await conn.readFloat();
await conn.writeFloat(num2);
// Read/write 64 bit integer
const num3 = await conn.readLong();
await conn.writeLong(num3);
// Read/write string
const string = await conn.readString();
await conn.writeString(string);
// Read/write object (JSON)
const obj = await conn.readJSON();
await conn.writeJSON(obj);Timeouts
setTimeout sets a timeout for when the connection is idle. If the socket is idle for the specified time, the connection will be closed.
setReadTimeout sets a timeout for read operations. If a timeout expires before the read operation completes, the read operation is cancelled and an exception is thrown.
// Set timeout for when the connection is idle
conn.setTimeout(10000); // 10 seconds
// Set timeout for read operations
conn.setReadTimeout(5000); // 5 secondsTCP Server
There are two options to implement TCP Server using NetService
Option 1 - Handler function
Accept a new connection on a loop and send each connection to a handler function. The main server function should not await the handler function so the server can handle multiple concurrent connections.
/**
* Example for a handler function, called when a connection is accepted
* @param {*} conn Connection object
*/
async function handlerFunc(conn) {
try {
let one = await conn.readInt();
let teststring = await conn.readString();
await conn.writeInt(2);
let myObj2 = await conn.readJSON();
console.log(myObj2);
} catch (err) {
console.log(err);
}
};
/**
* Example server
*/
async function mainServer() {
try {
const port = 11481;
netService = new NetService(port,NetConn);
// listen for connections
await netService.listen();
console.log(`Listening on port ${port}`);
let serverConn;
// accept connections
while (serverConn = await netService.accept()) {
console.log(`Accepted connection from ${serverConn.socket.remoteAddress}:${serverConn.socket.remotePort}`);
handlerFunc(serverConn); // start handler - do not await!
}
} catch (err) {
console.log(err);
}
}Option 2 - Extend NetConn class
Create a class that extends the NetConn and overrides the constructor. When the constructor called start a handler function.
When creating the NetService object, reference your class.
let netService;
/**
* Example for a server connection class - This class extends NetConn and adds
* call to processData() in the constructor. This is where you would
* implement your server connection logic.
*/
class ExampleServerConn extends NetConn {
constructor(socket, server, options, logger) {
super(socket, server, options, logger);
console.log(`TestServerConn: connected to ${socket.remoteAddress}:${socket.remotePort}`);
this.processData();
}
async processData() {
try {
const conn = this;
let one = await conn.readInt();
let teststring = await conn.readString();
await conn.writeInt(2);
let myObj = {
a: 1,
b: 'test',
c: [1, 2, 3]
}
await conn.writeJSON(myObj);
let myObj2 = await conn.readJSON();
console.log(myObj2);
if (myObj2.command === 'quit') {
netService.close();
}
} catch (err) {
console.log(err);
}
}
}
/**
* Example server
*/
async function mainServer() {
try {
const port = 11481;
// create server, passing in connection class
netService = new NetService(port,ExampleServerConn);
// listen for connections
await netService.listen();
console.log(`Listening on port ${port}`);
} catch (err) {
console.log(err);
}
}TLS Server
Implement TLS server exactly the same as TCP Server, but add TLS options to NetService arguments
// create server, passing in port, connection class, and TLS options
const tlsOptions = {
key: await fs.promises.readFile('server.key'),
cert: await fs.promises.readFile('server.crt')
};
const port = 11443;
netService = new NetService(port,ExampleServerConn,tlsOptions);
// listen for connections
await netService.listen();
console.log(`Listening on port ${port} using TLS`);Examples
Examples of java script files are available in the examples folder
The json-server.js and json-client.js demonstrate server and client that communicate with JSON messages.
This will help you to implement a very simple protocol for asynchronous communication between client and server.