server-chat.js•7.01 kB
// **BEFORE RUNNING THIS SCRIPT:**
// 1. The server portion is best run on non-Windows systems because they have
// terminfo databases which are needed to properly work with different
// terminal types of client connections
// 2. Install `blessed`: `npm install blessed`
// 3. Create a server host key in this same directory and name it `host.key`
'use strict';
const { readFileSync } = require('fs');
const blessed = require('blessed');
const { Server } = require('ssh2');
const RE_SPECIAL =
// eslint-disable-next-line no-control-regex
/[\x00-\x1F\x7F]+|(?:\x1B\[([0-9]{1,2}(;[0-9]{1,2})?)?[m|K])/g;
const MAX_MSG_LEN = 128;
const MAX_NAME_LEN = 10;
const PROMPT_NAME = `Enter a nickname to use (max ${MAX_NAME_LEN} chars): `;
const users = [];
function formatMessage(msg, output) {
output.parseTags = true;
msg = output._parseTags(msg);
output.parseTags = false;
return msg;
}
function userBroadcast(msg, source) {
const sourceMsg = `> ${msg}`;
const name = `{cyan-fg}{bold}${source.name}{/}`;
msg = `: ${msg}`;
for (const user of users) {
const output = user.output;
if (source === user)
output.add(sourceMsg);
else
output.add(formatMessage(name, output) + msg);
}
}
function localMessage(msg, source) {
const output = source.output;
output.add(formatMessage(msg, output));
}
function noop(v) {}
new Server({
hostKeys: [readFileSync('host.key')],
}, (client) => {
let stream;
let name;
client.on('authentication', (ctx) => {
let nick = ctx.username;
let prompt = PROMPT_NAME;
let lowered;
// Try to use username as nickname
if (nick.length > 0 && nick.length <= MAX_NAME_LEN) {
lowered = nick.toLowerCase();
let ok = true;
for (const user of users) {
if (user.name.toLowerCase() === lowered) {
ok = false;
prompt = `That nickname is already in use.\n${PROMPT_NAME}`;
break;
}
}
if (ok) {
name = nick;
return ctx.accept();
}
} else if (nick.length === 0) {
prompt = 'A nickname is required.\n' + PROMPT_NAME;
} else {
prompt = 'That nickname is too long.\n' + PROMPT_NAME;
}
if (ctx.method !== 'keyboard-interactive')
return ctx.reject(['keyboard-interactive']);
ctx.prompt(prompt, function retryPrompt(answers) {
if (answers.length === 0)
return ctx.reject(['keyboard-interactive']);
nick = answers[0];
if (nick.length > MAX_NAME_LEN) {
return ctx.prompt(`That nickname is too long.\n${PROMPT_NAME}`,
retryPrompt);
} else if (nick.length === 0) {
return ctx.prompt(`A nickname is required.\n${PROMPT_NAME}`,
retryPrompt);
}
lowered = nick.toLowerCase();
for (const user of users) {
if (user.name.toLowerCase() === lowered) {
return ctx.prompt(`That nickname is already in use.\n${PROMPT_NAME}`,
retryPrompt);
}
}
name = nick;
ctx.accept();
});
}).on('ready', () => {
let rows;
let cols;
let term;
client.once('session', (accept, reject) => {
accept().once('pty', (accept, reject, info) => {
rows = info.rows;
cols = info.cols;
term = info.term;
accept && accept();
}).on('window-change', (accept, reject, info) => {
rows = info.rows;
cols = info.cols;
if (stream) {
stream.rows = rows;
stream.columns = cols;
stream.emit('resize');
}
accept && accept();
}).once('shell', (accept, reject) => {
stream = accept();
users.push(stream);
stream.name = name;
stream.rows = rows || 24;
stream.columns = cols || 80;
stream.isTTY = true;
stream.setRawMode = noop;
stream.on('error', noop);
const screen = new blessed.screen({
autoPadding: true,
smartCSR: true,
program: new blessed.program({
input: stream,
output: stream
}),
terminal: term || 'ansi'
});
screen.title = 'SSH Chatting as ' + name;
// Disable local echo
screen.program.attr('invisible', true);
const output = stream.output = new blessed.log({
screen: screen,
top: 0,
left: 0,
width: '100%',
bottom: 2,
scrollOnInput: true
});
screen.append(output);
screen.append(new blessed.box({
screen: screen,
height: 1,
bottom: 1,
left: 0,
width: '100%',
type: 'line',
ch: '='
}));
const input = new blessed.textbox({
screen: screen,
bottom: 0,
height: 1,
width: '100%',
inputOnFocus: true
});
screen.append(input);
input.focus();
// Local greetings
localMessage('{blue-bg}{white-fg}{bold}Welcome to SSH Chat!{/}\n'
+ 'There are {bold}'
+ (users.length - 1)
+ '{/} other user(s) connected.\n'
+ 'Type /quit or /exit to exit the chat.',
stream);
// Let everyone else know that this user just joined
for (const user of users) {
const output = user.output;
if (user === stream)
continue;
output.add(formatMessage('{green-fg}*** {bold}', output)
+ name
+ formatMessage('{/bold} has joined the chat{/}', output));
}
screen.render();
// XXX This fake resize event is needed for some terminals in order to
// have everything display correctly
screen.program.emit('resize');
// Read a line of input from the user
input.on('submit', (line) => {
input.clearValue();
screen.render();
if (!input.focused)
input.focus();
line = line.replace(RE_SPECIAL, '').trim();
if (line.length > MAX_MSG_LEN)
line = line.substring(0, MAX_MSG_LEN);
if (line.length > 0) {
if (line === '/quit' || line === '/exit')
stream.end();
else
userBroadcast(line, stream);
}
});
});
});
}).on('close', () => {
if (stream !== undefined) {
users.splice(users.indexOf(stream), 1);
// Let everyone else know that this user just left
for (const user of users) {
const output = user.output;
output.add(formatMessage('{magenta-fg}*** {bold}', output)
+ name
+ formatMessage('{/bold} has left the chat{/}', output));
}
}
}).on('error', (err) => {
// Ignore errors
});
}).listen(0, function() {
console.log('Listening on port ' + this.address().port);
});