webserver.mjs

/*
 * Copyright 2014 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* eslint-disable no-var */

import fs from "fs";
import http from "http";
import path from "path";

var mimeTypes = {
  ".css": "text/css",
  ".html": "text/html",
  ".js": "application/javascript",
  ".mjs": "application/javascript",
  ".json": "application/json",
  ".svg": "image/svg+xml",
  ".pdf": "application/pdf",
  ".xhtml": "application/xhtml+xml",
  ".gif": "image/gif",
  ".ico": "image/x-icon",
  ".png": "image/png",
  ".log": "text/plain",
  ".bcmap": "application/octet-stream",
  ".ftl": "text/plain",
};

var defaultMimeType = "application/octet-stream";

function WebServer() {
  this.root = ".";
  this.host = "localhost";
  this.port = 0;
  this.server = null;
  this.verbose = false;
  this.cacheExpirationTime = 0;
  this.disableRangeRequests = false;
  this.hooks = {
    GET: [crossOriginHandler],
    POST: [],
  };
}
WebServer.prototype = {
  start(callback) {
    this._ensureNonZeroPort();
    this.server = http.createServer(this._handler.bind(this));
    this.server.listen(this.port, this.host, callback);
    console.log(
      "Server running at http://" + this.host + ":" + this.port + "/"
    );
  },
  stop(callback) {
    this.server.close(callback);
    this.server = null;
  },
  _ensureNonZeroPort() {
    if (!this.port) {
      // If port is 0, a random port will be chosen instead. Do not set a host
      // name to make sure that the port is synchronously set by .listen().
      var server = http.createServer().listen(0);
      var address = server.address();
      // .address().port being available synchronously is merely an
      // implementation detail. So we are defensive here and fall back to some
      // fixed port when the address is not available yet.
      this.port = address ? address.port : 8000;
      server.close();
    }
  },
  _handler(req, res) {
    var url = req.url.replaceAll("//", "/");
    var urlParts = /([^?]*)((?:\?(.*))?)/.exec(url);
    try {
      // Guard against directory traversal attacks such as
      // `/../../../../../../../etc/passwd`, which let you make GET requests
      // for files outside of `this.root`.
      var pathPart = path.normalize(decodeURI(urlParts[1]));
      // path.normalize returns a path on the basis of the current platform.
      // Windows paths cause issues in statFile and serverDirectoryIndex.
      // Converting to unix path would avoid platform checks in said functions.
      pathPart = pathPart.replaceAll("\\", "/");
    } catch {
      // If the URI cannot be decoded, a `URIError` is thrown. This happens for
      // malformed URIs such as `http://localhost:8888/%s%s` and should be
      // handled as a bad request.
      res.writeHead(400);
      res.end("Bad request", "utf8");
      return;
    }
    var queryPart = urlParts[3];
    var verbose = this.verbose;

    var methodHooks = this.hooks[req.method];
    if (!methodHooks) {
      res.writeHead(405);
      res.end("Unsupported request method", "utf8");
      return;
    }
    var handled = methodHooks.some(function (hook) {
      return hook(req, res);
    });
    if (handled) {
      return;
    }

    if (pathPart === "/favicon.ico") {
      fs.realpath(
        path.join(this.root, "test/resources/favicon.ico"),
        checkFile
      );
      return;
    }

    var disableRangeRequests = this.disableRangeRequests;
    var cacheExpirationTime = this.cacheExpirationTime;

    var filePath;
    fs.realpath(path.join(this.root, pathPart), checkFile);

    function checkFile(err, file) {
      if (err) {
        res.writeHead(404);
        res.end();
        if (verbose) {
          console.error(url + ": not found");
        }
        return;
      }
      filePath = file;
      fs.stat(filePath, statFile);
    }

    var fileSize;

    function statFile(err, stats) {
      if (err) {
        res.writeHead(500);
        res.end();
        return;
      }

      fileSize = stats.size;
      var isDir = stats.isDirectory();
      if (isDir && !/\/$/.test(pathPart)) {
        res.setHeader("Location", pathPart + "/" + urlParts[2]);
        res.writeHead(301);
        res.end("Redirected", "utf8");
        return;
      }
      if (isDir) {
        serveDirectoryIndex(filePath);
        return;
      }

      var range = req.headers.range;
      if (range && !disableRangeRequests) {
        var rangesMatches = /^bytes=(\d+)-(\d+)?/.exec(range);
        if (!rangesMatches) {
          res.writeHead(501);
          res.end("Bad range", "utf8");
          if (verbose) {
            console.error(url + ': bad range: "' + range + '"');
          }
          return;
        }
        var start = +rangesMatches[1];
        var end = +rangesMatches[2];
        if (verbose) {
          console.log(url + ": range " + start + " - " + end);
        }
        serveRequestedFileRange(
          filePath,
          start,
          isNaN(end) ? fileSize : end + 1
        );
        return;
      }
      if (verbose) {
        console.log(url);
      }
      serveRequestedFile(filePath);
    }

    function escapeHTML(untrusted) {
      // Escape untrusted input so that it can safely be used in a HTML response
      // in HTML and in HTML attributes.
      return untrusted
        .replaceAll("&", "&")
        .replaceAll("<", "&lt;")
        .replaceAll(">", "&gt;")
        .replaceAll('"', "&quot;")
        .replaceAll("'", "&#39;");
    }

    function serveDirectoryIndex(dir) {
      res.setHeader("Content-Type", "text/html");
      res.writeHead(200);

      if (queryPart === "frame") {
        res.end(
          "<html><frameset cols=*,200><frame name=pdf>" +
            '<frame src="' +
            encodeURI(pathPart) +
            '?side"></frameset></html>',
          "utf8"
        );
        return;
      }
      var all = queryPart === "all";
      fs.readdir(dir, function (err, files) {
        if (err) {
          res.end();
          return;
        }
        res.write(
          '<html><head><meta charset="utf-8"></head><body>' +
            "<h1>PDFs of " +
            pathPart +
            "</h1>\n"
        );
        if (pathPart !== "/") {
          res.write('<a href="..">..</a><br>\n');
        }
        files.forEach(function (file) {
          var stat;
          var item = pathPart + file;
          var href = "";
          var label = "";
          var extraAttributes = "";
          try {
            stat = fs.statSync(path.join(dir, file));
          } catch (e) {
            href = encodeURI(item);
            label = file + " (" + e + ")";
            extraAttributes = ' style="color:red"';
          }
          if (stat) {
            if (stat.isDirectory()) {
              href = encodeURI(item);
              label = file;
            } else if (path.extname(file).toLowerCase() === ".pdf") {
              href = "/web/viewer.html?file=" + encodeURIComponent(item);
              label = file;
              extraAttributes = ' target="pdf"';
            } else if (all) {
              href = encodeURI(item);
              label = file;
            }
          }
          if (label) {
            res.write(
              '<a href="' +
                escapeHTML(href) +
                '"' +
                extraAttributes +
                ">" +
                escapeHTML(label) +
                "</a><br>\n"
            );
          }
        });
        if (files.length === 0) {
          res.write("<p>no files found</p>\n");
        }
        if (!all && queryPart !== "side") {
          res.write(
            "<hr><p>(only PDF files are shown, " +
              '<a href="?all">show all</a>)</p>\n'
          );
        }
        res.end("</body></html>");
      });
    }

    function serveRequestedFile(reqFilePath) {
      var stream = fs.createReadStream(reqFilePath, { flags: "rs" });

      stream.on("error", function (error) {
        res.writeHead(500);
        res.end();
      });

      var ext = path.extname(reqFilePath).toLowerCase();
      var contentType = mimeTypes[ext] || defaultMimeType;

      if (!disableRangeRequests) {
        res.setHeader("Accept-Ranges", "bytes");
      }
      res.setHeader("Content-Type", contentType);
      res.setHeader("Content-Length", fileSize);
      if (cacheExpirationTime > 0) {
        var expireTime = new Date();
        expireTime.setSeconds(expireTime.getSeconds() + cacheExpirationTime);
        res.setHeader("Expires", expireTime.toUTCString());
      }
      res.writeHead(200);

      stream.pipe(res);
    }

    function serveRequestedFileRange(reqFilePath, start, end) {
      var stream = fs.createReadStream(reqFilePath, {
        flags: "rs",
        start,
        end: end - 1,
      });

      stream.on("error", function (error) {
        res.writeHead(500);
        res.end();
      });

      var ext = path.extname(reqFilePath).toLowerCase();
      var contentType = mimeTypes[ext] || defaultMimeType;

      res.setHeader("Accept-Ranges", "bytes");
      res.setHeader("Content-Type", contentType);
      res.setHeader("Content-Length", end - start);
      res.setHeader(
        "Content-Range",
        "bytes " + start + "-" + (end - 1) + "/" + fileSize
      );
      res.writeHead(206);

      stream.pipe(res);
    }
  },
};

// This supports the "Cross-origin" test in test/unit/api_spec.js
// It is here instead of test.js so that when the test will still complete as
// expected if the user does "gulp server" and then visits
// http://localhost:8888/test/unit/unit_test.html?spec=Cross-origin
function crossOriginHandler(req, res) {
  if (req.url === "/test/pdfs/basicapi.pdf?cors=withCredentials") {
    res.setHeader("Access-Control-Allow-Origin", req.headers.origin);
    res.setHeader("Access-Control-Allow-Credentials", "true");
  }
  if (req.url === "/test/pdfs/basicapi.pdf?cors=withoutCredentials") {
    res.setHeader("Access-Control-Allow-Origin", req.headers.origin);
  }
}

export { WebServer };