enigma-bbs/core/telnet_bridge.js

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/* jslint node: true */
'use strict';
// ENiGMA½
const MenuModule = require('./menu_module.js').MenuModule;
const resetScreen = require('./ansi_term.js').resetScreen;
const setSyncTermFontWithAlias = require('./ansi_term.js').setSyncTermFontWithAlias;
// deps
const async = require('async');
const _ = require('lodash');
const net = require('net');
const EventEmitter = require('events');
const {
TelnetSocket,
TelnetSpec :
{
Commands,
Options,
SubNegotiationCommands,
},
} = require('telnet-socket');
/*
Expected configuration block:
{
module: telnet_bridge
...
config: {
host: somehost.net
port: 23
}
}
*/
// :TODO: ENH: Support nodeMax and tooManyArt
exports.moduleInfo = {
name : 'Telnet Bridge',
desc : 'Connect to other Telnet Systems',
author : 'Andrew Pamment',
};
const IAC_DO_TERM_TYPE = TelnetSocket.commandBuffer(
Commands.DO,
2020-06-16 01:08:55 +00:00
Options.TTYPE
);
class TelnetClientConnection extends EventEmitter {
constructor(client) {
super();
this.client = client;
this.dataHits = 0;
}
updateActivity() {
if (0 === (this.dataHits++ % 4)) {
this.client.explicitActivityTimeUpdate();
}
}
restorePipe() {
if(!this.pipeRestored) {
this.pipeRestored = true;
this.client.restoreDataHandler();
// client may have bailed
if(null !== _.get(this, 'client.term.output', null)) {
if(this.bridgeConnection) {
this.client.term.output.unpipe(this.bridgeConnection);
}
this.client.term.output.resume();
}
}
}
connect(connectOpts) {
this.bridgeConnection = net.createConnection(connectOpts, () => {
this.emit('connected');
this.pipeRestored = false;
this.client.setTemporaryDirectDataHandler(data => {
this.updateActivity();
this.bridgeConnection.write(data);
});
});
this.bridgeConnection.on('data', data => {
this.updateActivity();
this.client.term.rawWrite(data);
//
// Wait for a terminal type request, and send it exactly once.
// This is enough (in additional to other negotiations handled in telnet.js)
// to get us in on most systems
//
if(!this.termSent && data.indexOf(IAC_DO_TERM_TYPE) > -1) {
this.termSent = true;
this.bridgeConnection.write(this.getTermTypeNegotiationBuffer());
}
});
this.bridgeConnection.once('end', () => {
this.restorePipe();
this.emit('end');
});
this.bridgeConnection.once('error', err => {
this.restorePipe();
this.emit('end', err);
});
}
disconnect() {
if(this.bridgeConnection) {
this.bridgeConnection.end();
}
}
destroy() {
if(this.bridgeConnection) {
this.bridgeConnection.destroy();
this.bridgeConnection.removeAllListeners();
this.restorePipe();
this.emit('end');
}
}
getTermTypeNegotiationBuffer() {
//
// Create a TERMINAL-TYPE sub negotiation buffer using the
// actual/current terminal type.
//
const sendTermType = TelnetSocket.commandBuffer(
Commands.SB,
Options.TTYPE,
[
SubNegotiationCommands.IS,
...Buffer.from(this.client.term.termType), // e.g. "ansi"
Commands.IAC,
Commands.SE,
]
);
return sendTermType;
}
}
exports.getModule = class TelnetBridgeModule extends MenuModule {
constructor(options) {
super(options);
this.config = Object.assign({}, _.get(options, 'menuConfig.config'), options.extraArgs);
this.config.port = this.config.port || 23;
}
initSequence() {
let clientTerminated;
const self = this;
async.series(
[
function validateConfig(callback) {
if(_.isString(self.config.host) &&
_.isNumber(self.config.port))
{
callback(null);
} else {
callback(new Error('Configuration is missing required option(s)'));
}
},
function createTelnetBridge(callback) {
const connectOpts = {
port : self.config.port,
host : self.config.host,
};
self.client.term.write(resetScreen());
self.client.term.write(
` Connecting to ${connectOpts.host}, please wait...\n (Press ESC to cancel)\n`
);
const telnetConnection = new TelnetClientConnection(self.client);
const connectionKeyPressHandler = (ch, key) => {
if('escape' === key.name) {
self.client.removeListener('key press', connectionKeyPressHandler);
telnetConnection.destroy();
}
};
self.client.on('key press', connectionKeyPressHandler);
telnetConnection.on('connected', () => {
self.client.removeListener('key press', connectionKeyPressHandler);
self.client.log.info(connectOpts, 'Telnet bridge connection established');
// put the font back how it was prior, if fonts are enabled
if(self.client.term.syncTermFontsEnabled && self.config.font) {
self.client.term.rawWrite(setSyncTermFontWithAlias(self.config.font));
}
self.client.once('end', () => {
self.client.log.info('Connection ended. Terminating connection');
clientTerminated = true;
telnetConnection.disconnect();
});
});
telnetConnection.on('end', err => {
self.client.removeListener('key press', connectionKeyPressHandler);
if(err) {
self.client.log.info(`Telnet bridge connection error: ${err.message}`);
}
callback(clientTerminated ? new Error('Client connection terminated') : null);
});
telnetConnection.connect(connectOpts);
}
],
err => {
if(err) {
self.client.log.warn( { error : err.message }, 'Telnet connection error');
}
if(!clientTerminated) {
self.prevMenu();
}
}
);
}
};