127 lines
3.9 KiB
JavaScript
127 lines
3.9 KiB
JavaScript
/**
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* Implementation of the Java Minecraft ping protocol.
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* @see https://wiki.vg/Server_List_Ping
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*/
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'use strict';
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import net from 'net';
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import varint from './varint.js';
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const PROTOCOL_VERSION = 0;
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function ping(host, port = 25565, cb, timeout = 5000) {
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const socket = net.createConnection(({ host, port }));
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// Set manual timeout interval.
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// This ensures the connection will NEVER hang regardless of internal state
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const timeoutTask = setTimeout(() => {
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socket.emit('error', new Error('Socket timeout'));
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}, timeout);
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const closeSocket = () => {
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socket.destroy();
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clearTimeout(timeoutTask);
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};
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// Generic error handler
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// This protects multiple error callbacks given the complex socket state
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// This is mostly dangerous since it can swallow errors
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let didFireError = false;
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const handleError = (err) => {
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closeSocket();
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if (!didFireError) {
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didFireError = true;
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cb(null, err);
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}
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};
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// #setNoDelay instantly flushes data during read/writes
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// This prevents the runtime from delaying the write at all
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socket.setNoDelay(true);
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socket.on('connect', () => {
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const handshake = varint.concat([
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varint.encodeInt(0),
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varint.encodeInt(PROTOCOL_VERSION),
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varint.encodeInt(host.length),
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varint.encodeString(host),
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varint.encodeUShort(port),
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varint.encodeInt(1)
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]);
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socket.write(handshake);
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const request = varint.concat([
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varint.encodeInt(0)
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]);
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socket.write(request);
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});
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let incomingBuffer = Buffer.alloc(0);
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socket.on('data', (data) => {
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incomingBuffer = Buffer.concat([incomingBuffer, data]);
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// Wait until incomingBuffer is at least 5 bytes long to ensure it has captured the first VarInt value
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// This value is used to determine the full read length of the response
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// "VarInts are never longer than 5 bytes"
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// https://wiki.vg/Data_types#VarInt_and_VarLong
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if (incomingBuffer.length < 5) {
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return;
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}
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let offset = 0;
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const packetLength = varint.decodeInt(incomingBuffer, offset);
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// Ensure incomingBuffer contains the full response
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if (incomingBuffer.length - offset < packetLength) {
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return;
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}
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const packetId = varint.decodeInt(incomingBuffer, varint.decodeLength(packetLength));
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if (packetId === 0) {
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const data = incomingBuffer.slice(varint.decodeLength(packetLength) + varint.decodeLength(packetId));
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const responseLength = varint.decodeInt(data, 0);
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const response = data.slice(varint.decodeLength(responseLength), varint.decodeLength(responseLength) + responseLength);
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try {
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const message = JSON.parse(response);
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cb(null, message);
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// Close the socket and clear the timeout task
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closeSocket();
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} catch (err) {
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handleError(err);
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}
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} else {
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handleError(new Error('Received unexpected packet'));
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}
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});
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socket.on('error', handleError);
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}
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/**
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* Asynchronously ping Minecraft Java server.
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*
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* The optional `options` argument can be an object with a `ping` (default is `25565`) or/and `timeout` (default is `5000`) property.
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*
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* @param {string} host The Java server address.
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* @param {import('../types/index.js').PingOptions} options The configuration for pinging Minecraft Java server.
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* @returns {Promise<import('../types/lib/java.js').JavaPingResponse>}
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*/
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export function pingJava(host, options = {}) {
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if (!host) throw new Error('Host argument is not provided');
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const { port = 25565, timeout = 5000 } = options;
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return new Promise((resolve, reject) => {
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ping(host, port, (err, res) => {
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err ? reject(err) : resolve(res);
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}, timeout);
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});
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} |