server.js

const log = require('book');
const Koa = require('koa');
const tldjs = require('tldjs');
const http = require('http');
const hri = require('human-readable-ids').hri;
const Router = require('koa-router');

const ClientManager = require('./lib/ClientManager');

function start (opt) {
    opt = opt || {};

    const validHosts = (opt.domain) ? [opt.domain, 'craigandersen.io'] : undefined;
    const myTldjs = tldjs.fromUserSettings({ validHosts });
    const landingPage = opt.landing || 'https://craigandersen.io';

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

    const manager = new ClientManager(opt);

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

    const app = new Koa();
    const router = new Router();

    router.get('/api/status', async (ctx, next) => {
        const stats = manager.stats;
        ctx.body = {
            tunnels: stats.tunnels,
            mem: process.memoryUsage(),
        };
    });

    router.get('/api/tunnels/:id/status', async (ctx, next) => {
        const clientId = ctx.params.id;
        const client = manager.getClient(clientId);
        if (!client) {
            ctx.throw(404);
            return;
        }

        const stats = client.stats();
        ctx.body = {
            connected_sockets: stats.connectedSockets,
        };
    });

    router.get('/api/destroy/:id', async (ctx, next) => {
        const { id } = ctx.params;
        const stats = manager.stats;
        const exists = manager.hasClient(id);
        if (exists) {
            manager.removeClient(id);
            ctx.body = {
                tunnels: stats.tunnels,
                success: true,
                message: `tunnel with id: ${id} destroyed`
            };
        } else {
            ctx.body = {
                tunnels: stats.tunnels,
                success: false,
                message: 'No matching id found'
            }
        }
    });

    app.use(router.routes());
    app.use(router.allowedMethods());

    // 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 reqId = hri.random();
            // console.log(`#1 making new client with id ${reqId}`);
            const info = await manager.newClient(reqId);
            const splitHost = ctx.request.host.split('.');
            splitHost.shift();
            const newHost = splitHost.join('.');

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

        // no new client request, send to landing page
        ctx.redirect(landingPage);
    });

    // 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 reqId = parts[1];

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

        // console.log(`#2 making new client with id ${reqId}`);
        const info = await manager.newClient(reqId);

        const splitHost = ctx.request.host.split('.');
        splitHost.shift();
        const newHost = splitHost.join('.');

        const url = schema + '://' + info.id + '.' + newHost;
        info.url = url;
        ctx.body = info;
        // console.log(`new client info: ${JSON.stringify(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;
        }

        const client = manager.getClient(clientId);
        if (!client) {
            res.statusCode = 404;
            // console.log('hit 404 on id', clientId);
            res.end('404');
            return;
        }

        client.handleRequest(req, res);
    });

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

        const clientId = GetClientIdFromHostname(hostname);
        // console.log('upgrade id', clientId);
        if (!clientId) {
            socket.destroy();
            return;
        }

        const client = manager.getClient(clientId);
        if (!client) {
            // console.log('destroy socket');
            socket.destroy();
            return;
        }

        client.handleUpgrade(req, socket);
    });

    return server;
};

module.exports = start;