server/server.js

import log from 'book';
import Koa from 'koa';
import tldjs from 'tldjs';
import Debug from 'debug';
import http from 'http';
import Promise from 'bluebird';

import ClientManager from './lib/ClientManager';
import rand_id from './lib/rand_id';

const debug = Debug('localtunnel:server');

function GetClientIdFromHostname(hostname) {
    return tldjs.getSubdomain(hostname);
}

module.exports = function(opt) {
    opt = opt || {};

    const manager = new ClientManager(opt);

    const schema = opt.secure ? 'https' : 'http';

    const app = new Koa();

    // api status endpoint
    app.use(async (ctx, next) => {
        const path = ctx.request.path;
        if (path !== '/api/status') {
            await next();
            return;
        }

        const stats = manager.stats;

        ctx.body = {
            tunnels: stats.tunnels,
            mem: process.memoryUsage(),
        };
    });

    // root endpoint
    app.use(async (ctx, next) => {
        const path = ctx.request.path;

        // skip anything not on the root path
        if (path !== '/') {
            await next();
            return;
        }

        const isNewClientRequest = ctx.query['new'] !== undefined;
        if (isNewClientRequest) {
            const req_id = rand_id();
            debug('making new client with id %s', req_id);
            const info = await manager.newClient(req_id);

            const url = schema + '://' + info.id + '.' + ctx.request.host;
            info.url = url;
            ctx.body = info;
            return;
        }

        // no new client request, send to landing page
        ctx.redirect('https://localtunnel.github.io/www/');
    });

    // anything after the / path is a request for a specific client name
    // This is a backwards compat feature
    app.use(async (ctx, next) => {
        const parts = ctx.request.path.split('/');

        // any request with several layers of paths is not allowed
        // rejects /foo/bar
        // allow /foo
        if (parts.length !== 2) {
            await next();
            return;
        }

        const req_id = parts[1];

        // limit requested hostnames to 63 characters
        if (! /^[a-z0-9]{4,63}$/.test(req_id)) {
            const msg = 'Invalid subdomain. Subdomains must be lowercase and between 4 and 63 alphanumeric characters.';
            ctx.status = 403;
            ctx.body = {
                message: msg,
            };
            return;
        }

        debug('making new client with id %s', req_id);
        const info = await manager.newClient(req_id);

        const url = schema + '://' + info.id + '.' + ctx.request.host;
        info.url = url;
        ctx.body = info;
        return;
    });

    const server = http.createServer();

    const appCallback = app.callback();
    server.on('request', (req, res) => {
        // without a hostname, we won't know who the request is for
        const hostname = req.headers.host;
        if (!hostname) {
            res.statusCode = 400;
            res.end('Host header is required');
            return;
        }

        const clientId = GetClientIdFromHostname(hostname);
        if (!clientId) {
            appCallback(req, res);
            return;
        }

        if (manager.hasClient(clientId)) {
            manager.handleRequest(clientId, req, res);
            return;
        }

        res.statusCode = 404;
        res.end('404');
    });

    server.on('upgrade', (req, socket, head) => {
        const hostname = req.headers.host;
        if (!hostname) {
            sock.destroy();
            return;
        }

        const clientId = GetClientIdFromHostname(hostname);
        if (!clientId) {
            sock.destroy();
            return;
        }

        if (manager.hasClient(clientId)) {
            manager.handleUpgrade(clientId, req, socket);
            return;
        }

        socket.destroy();
    });

    return server;
};