server.cjs

/*eslint-env node*/
/* eslint-disable no-unused-vars */
/* eslint-disable global-require */
"use strict";
(function () {
  const express = require("express");
  const compression = require("compression");
  const fs = require("fs");
  const url = require("url");
  const request = require("request");

  const gzipHeader = Buffer.from("1F8B08", "hex");

  const yargs = require("yargs").options({
    port: {
      default: 8080,
      description: "Port to listen on.",
    },
    public: {
      type: "boolean",
      description: "Run a public server that listens on all interfaces.",
    },
    "upstream-proxy": {
      description:
        'A standard proxy server that will be used to retrieve data.  Specify a URL including port, e.g. "http://proxy:8000".',
    },
    "bypass-upstream-proxy-hosts": {
      description:
        'A comma separated list of hosts that will bypass the specified upstream_proxy, e.g. "lanhost1,lanhost2"',
    },
    help: {
      alias: "h",
      type: "boolean",
      description: "Show this help.",
    },
  });
  const argv = yargs.argv;

  if (argv.help) {
    return yargs.showHelp();
  }

  // eventually this mime type configuration will need to change
  // https://github.com/visionmedia/send/commit/d2cb54658ce65948b0ed6e5fb5de69d022bef941
  // *NOTE* Any changes you make here must be mirrored in web.config.
  const mime = express.static.mime;
  mime.define(
    {
      "application/json": ["czml", "json", "geojson", "topojson"],
      "application/wasm": ["wasm"],
      "image/ktx2": ["ktx2"],
      "model/gltf+json": ["gltf"],
      "model/gltf-binary": ["bgltf", "glb"],
      "application/octet-stream": [
        "b3dm",
        "pnts",
        "i3dm",
        "cmpt",
        "geom",
        "vctr",
      ],
      "text/plain": ["glsl"],
    },
    true
  );

  const app = express();
  app.use(compression());
  app.use(function (req, res, next) {
    res.header("Access-Control-Allow-Origin", "*");
    res.header(
      "Access-Control-Allow-Headers",
      "Origin, X-Requested-With, Content-Type, Accept"
    );
    next();
  });

  function checkGzipAndNext(req, res, next) {
    const reqUrl = url.parse(req.url, true);
    const filePath = reqUrl.pathname.substring(1);

    const readStream = fs.createReadStream(filePath, { start: 0, end: 2 });
    readStream.on("error", function (err) {
      next();
    });

    readStream.on("data", function (chunk) {
      if (chunk.equals(gzipHeader)) {
        res.header("Content-Encoding", "gzip");
      }
      next();
    });
  }

  const knownTilesetFormats = [
    /\.b3dm/,
    /\.pnts/,
    /\.i3dm/,
    /\.cmpt/,
    /\.glb/,
    /\.geom/,
    /\.vctr/,
    /tileset.*\.json$/,
  ];
  app.get(knownTilesetFormats, checkGzipAndNext);

  app.use(express.static(__dirname));

  function getRemoteUrlFromParam(req) {
    let remoteUrl = req.params[0];
    if (remoteUrl) {
      // add http:// to the URL if no protocol is present
      if (!/^https?:\/\//.test(remoteUrl)) {
        remoteUrl = `http://${remoteUrl}`;
      }
      remoteUrl = url.parse(remoteUrl);
      // copy query string
      remoteUrl.search = url.parse(req.url).search;
    }
    return remoteUrl;
  }

  const dontProxyHeaderRegex = /^(?:Host|Proxy-Connection|Connection|Keep-Alive|Transfer-Encoding|TE|Trailer|Proxy-Authorization|Proxy-Authenticate|Upgrade)$/i;

  function filterHeaders(req, headers) {
    const result = {};
    // filter out headers that are listed in the regex above
    Object.keys(headers).forEach(function (name) {
      if (!dontProxyHeaderRegex.test(name)) {
        result[name] = headers[name];
      }
    });
    return result;
  }

  const upstreamProxy = argv["upstream-proxy"];
  const bypassUpstreamProxyHosts = {};
  if (argv["bypass-upstream-proxy-hosts"]) {
    argv["bypass-upstream-proxy-hosts"].split(",").forEach(function (host) {
      bypassUpstreamProxyHosts[host.toLowerCase()] = true;
    });
  }

  app.get("/proxy/*", function (req, res, next) {
    // look for request like http://localhost:8080/proxy/http://example.com/file?query=1
    let remoteUrl = getRemoteUrlFromParam(req);
    if (!remoteUrl) {
      // look for request like http://localhost:8080/proxy/?http%3A%2F%2Fexample.com%2Ffile%3Fquery%3D1
      remoteUrl = Object.keys(req.query)[0];
      if (remoteUrl) {
        remoteUrl = url.parse(remoteUrl);
      }
    }

    if (!remoteUrl) {
      return res.status(400).send("No url specified.");
    }

    if (!remoteUrl.protocol) {
      remoteUrl.protocol = "http:";
    }

    let proxy;
    if (upstreamProxy && !(remoteUrl.host in bypassUpstreamProxyHosts)) {
      proxy = upstreamProxy;
    }

    // encoding : null means "body" passed to the callback will be raw bytes

    request.get(
      {
        url: url.format(remoteUrl),
        headers: filterHeaders(req, req.headers),
        encoding: null,
        proxy: proxy,
      },
      function (error, response, body) {
        let code = 500;

        if (response) {
          code = response.statusCode;
          res.header(filterHeaders(req, response.headers));
        }

        res.status(code).send(body);
      }
    );
  });

  const server = app.listen(
    argv.port,
    argv.public ? undefined : "localhost",
    function () {
      if (argv.public) {
        console.log(
          "Cesium development server running publicly.  Connect to http://localhost:%d/",
          server.address().port
        );
      } else {
        console.log(
          "Cesium development server running locally.  Connect to http://localhost:%d/",
          server.address().port
        );
      }
    }
  );

  server.on("error", function (e) {
    if (e.code === "EADDRINUSE") {
      console.log(
        "Error: Port %d is already in use, select a different port.",
        argv.port
      );
      console.log("Example: node server.cjs --port %d", argv.port + 1);
    } else if (e.code === "EACCES") {
      console.log(
        "Error: This process does not have permission to listen on port %d.",
        argv.port
      );
      if (argv.port < 1024) {
        console.log("Try a port number higher than 1024.");
      }
    }
    console.log(e);
    process.exit(1);
  });

  server.on("close", function () {
    console.log("Cesium development server stopped.");
  });

  let isFirstSig = true;
  process.on("SIGINT", function () {
    if (isFirstSig) {
      console.log("Cesium development server shutting down.");
      server.close(function () {
        process.exit(0);
      });
      isFirstSig = false;
    } else {
      console.log("Cesium development server force kill.");
      process.exit(1);
    }
  });
})();