155 lines
4.1 KiB
JavaScript
155 lines
4.1 KiB
JavaScript
import { IPresetAddressing } from './defs';
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import {
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AdvancedBuffer,
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dumpHex,
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getRandomChunks,
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isValidHostname,
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isValidPort,
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numberToBuffer as ntb,
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} from '../utils';
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const CMD_NEW_CONN = 0x00;
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const CMD_DATA_FRAME = 0x01;
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const CMD_CLOSE_CONN = 0x02;
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/**
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* @description
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* Multiplexing protocol.
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*
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* @protocol
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*
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* # New Connection (client -> server)
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* +-------+-------+------+----------+----------+
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* | CMD | CID | ALEN | DST.ADDR | DST.PORT |
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* +-------+-------+------+----------+----------+ + [Data Frames]
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* | 0x0 | 4 | 1 | Variable | 2 |
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* +-------+-------+------+----------+----------+
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*
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* # Data Frames (client <-> server)
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* +-------+-------+------------+-------------+
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* | CMD | CID | DATA LEN | DATA |
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* +-------+-------+------------+-------------+
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* | 0x1 | 4 | 2 | Variable |
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* +-------+-------+------------+-------------+
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*
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* # Close Connection (client <-> server)
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* +-------+-------+
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* | CMD | CID |
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* +-------+-------+
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* | 0x2 | 4 |
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* +-------+-------+
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*
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*/
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export default class MuxPreset extends IPresetAddressing {
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static isPrivate = true;
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_adBuf = null;
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onInit() {
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this._adBuf = new AdvancedBuffer({ getPacketLength: this.onReceiving.bind(this) });
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this._adBuf.on('data', this.onChunkReceived.bind(this));
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}
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onDestroy() {
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this._adBuf.clear();
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this._adBuf = null;
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}
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onReceiving(buffer, { fail }) {
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if (buffer.length < 5) {
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return; // too short, continue to recv
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}
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const cmd = buffer[0];
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switch (cmd) {
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case CMD_NEW_CONN:
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if (buffer.length < 8 + buffer[5]) {
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return;
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}
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return 8 + buffer[5];
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case CMD_DATA_FRAME:
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if (buffer.length < 7) {
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return;
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}
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return 7 + buffer.readUInt16BE(5);
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case CMD_CLOSE_CONN:
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return 5;
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default:
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fail(`unknown cmd=${cmd} dump=${dumpHex(buffer)}`);
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return -1;
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}
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}
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onChunkReceived(chunk, { fail }) {
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const cmd = chunk[0];
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const cid = chunk.slice(1, 5).toString('hex');
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switch (cmd) {
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case CMD_NEW_CONN: {
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const hostBuf = chunk.slice(6, -2);
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const host = hostBuf.toString();
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const port = chunk.readUInt16BE(6 + chunk[5]);
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if (!isValidHostname(host) || !isValidPort(port)) {
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return fail(`invalid host or port, host=${dumpHex(hostBuf)} port=${port}`);
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}
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return this.muxNewConn({ cid, host, port });
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}
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case CMD_DATA_FRAME: {
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const dataLen = chunk.readUInt16BE(5);
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return this.muxDataFrame({ cid, data: chunk.slice(-dataLen) });
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}
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case CMD_CLOSE_CONN:
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return this.muxCloseConn({ cid });
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}
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}
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createDataFrames(cid, data) {
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const chunks = getRandomChunks(data, 0x0800, 0x3fff).map((chunk) =>
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Buffer.concat([ntb(CMD_DATA_FRAME, 1), cid, ntb(chunk.length), chunk])
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);
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return Buffer.concat(chunks);
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}
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createNewConn(host, port, cid) {
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const _host = Buffer.from(host);
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const _port = ntb(port);
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return Buffer.concat([ntb(CMD_NEW_CONN, 1), cid, ntb(_host.length, 1), _host, _port]);
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}
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createCloseConn(cid) {
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return Buffer.concat([ntb(CMD_CLOSE_CONN, 1), cid]);
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}
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clientOut({ buffer, fail }, { host, port, cid, isClosing }) {
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if (cid !== undefined) {
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const _cid = Buffer.from(cid, 'hex');
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if (isClosing) {
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return this.createCloseConn(_cid);
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}
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const dataFrames = this.createDataFrames(_cid, buffer);
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if (host && port) {
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return Buffer.concat([this.createNewConn(host, port, _cid), dataFrames]);
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}
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return dataFrames;
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} else {
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fail(`cid is not provided, drop buffer=${dumpHex(buffer)}`);
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}
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}
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serverOut({ buffer, fail }, { cid, isClosing }) {
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if (cid !== undefined) {
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const _cid = Buffer.from(cid, 'hex');
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if (isClosing) {
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return this.createCloseConn(_cid);
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}
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return this.createDataFrames(_cid, buffer);
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} else {
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fail(`cid is not provided, drop buffer=${dumpHex(buffer)}`);
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}
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}
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beforeIn({ buffer, fail }) {
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this._adBuf.put(buffer, { fail });
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}
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}
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