Minetrack/lib/server.js

const http = require("http");
const format = require("util").format;

const WebSocket = require("ws");
const finalHttpHandler = require("finalhandler");
const serveStatic = require("serve-static");

const logger = require("./logger");

const HASHED_FAVICON_URL_REGEX = /hashedfavicon_([a-z0-9]{32}).png/g;

function getRemoteAddr(req) {
  return (
    req.headers["cf-connecting-ip"] ||
    req.headers["x-forwarded-for"] ||
    req.connection.remoteAddress
  );
}

class Server {
  static getHashedFaviconUrl(hash) {
    // Format must be compatible with HASHED_FAVICON_URL_REGEX
    return format("/hashedfavicon_%s.png", hash);
  }

  constructor(app) {
    this._app = app;

    this.createHttpServer();
    this.createWebSocketServer();
  }

  createHttpServer() {
    const distServeStatic = serveStatic("dist/");
    const faviconsServeStatic = serveStatic("favicons/");

    this._http = http.createServer((req, res) => {
      logger.log("info", "%s requested: %s", getRemoteAddr(req), req.url);

      // Test the URL against a regex for hashed favicon URLs
      // Require only 1 match ([0]) and test its first captured group ([1])
      // Any invalid value or hit miss will pass into static handlers below
      const faviconHash = [...req.url.matchAll(HASHED_FAVICON_URL_REGEX)];

      if (
        faviconHash.length === 1 &&
        this.handleFaviconRequest(res, faviconHash[0][1])
      ) {
        return;
      }

      // Attempt to handle req using distServeStatic, otherwise fail over to faviconServeStatic
      // If faviconServeStatic fails, pass to finalHttpHandler to terminate
      distServeStatic(req, res, () => {
        faviconsServeStatic(req, res, finalHttpHandler(req, res));
      });
    });
  }

  handleFaviconRequest = (res, faviconHash) => {
    for (const serverRegistration of this._app.serverRegistrations) {
      if (
        serverRegistration.faviconHash &&
        serverRegistration.faviconHash === faviconHash
      ) {
        const buf = Buffer.from(
          serverRegistration.lastFavicon.split(",")[1],
          "base64"
        );

        res
          .writeHead(200, {
            "Content-Type": "image/png",
            "Content-Length": buf.length,
            "Cache-Control": "public, max-age=604800", // Cache hashed favicon for 7 days
          })
          .end(buf);

        return true;
      }
    }

    return false;
  };

  createWebSocketServer() {
    this._wss = new WebSocket.Server({
      server: this._http,
    });

    this._wss.on("connection", (client, req) => {
      logger.log(
        "info",
        "%s connected, total clients: %d",
        getRemoteAddr(req),
        this.getConnectedClients()
      );

      // Bind disconnect event for logging
      client.on("close", () => {
        logger.log(
          "info",
          "%s disconnected, total clients: %d",
          getRemoteAddr(req),
          this.getConnectedClients()
        );
      });

      // Pass client off to proxy handler
      this._app.handleClientConnection(client);
    });
  }

  listen(host, port) {
    this._http.listen(port, host);

    logger.log("info", "Started on %s:%d", host, port);
  }

  broadcast(payload) {
    this._wss.clients.forEach((client) => {
      if (client.readyState === WebSocket.OPEN) {
        client.send(payload);
      }
    });
  }

  getConnectedClients() {
    let count = 0;
    this._wss.clients.forEach((client) => {
      if (client.readyState === WebSocket.OPEN) {
        count++;
      }
    });
    return count;
  }
}

module.exports = Server;