lib.js

//   Copyright 2012 Patrick Wang (kk1fff)
//
//   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.

// Node.js libraries.
var http = require("http");
var url  = require("url");
var path = require("path");
var fs   = require("fs");

// Depended libraries.
var mime = require("mime");

exports.getServeFunction = function(baseDir, setting) {
  if (!setting) {
    setting = {};
  }

  // Configurations
  var logFormat    = ["client_ip", "req_method", "req_path", "req_host",
                      "resp_code", "actual_path", "error"];
  var defaultFile  = ["index.html", "index.htm"];
  var cacheAllowed = false;
  var cacheSecond  = 3600;
  var serverPort = 8080;

  // ---------------------------------------------------------------------------

  var logOutputFunc = console.log;

  var logger = function(log) {
    if (log instanceof Object) {
      var out = "";
      for (var i = 0; i < logFormat.length; i++) {
        if (log.hasOwnProperty(logFormat[i])) {
          out += (log[logFormat[i]] + " ");
        }
      }
      logOutputFunc(out);
    } else {
      logOutputFunc(log);
    }
  };

  var sendError404 = function(resp, log, error) {
    resp.statusCode = 404;
    resp.end();

    error = error || "Error: 404";

    log['resp_code'] = 404;
    log['error'] = error;
    logger(log);
  };

  var tryDefaultFile = function(p, serveFileFunc, req, resp, log, count) {
    count = count || 0;

    if (count < defaultFile.length) {
      fs.stat(p + "/" + defaultFile[count], function(err, stats) {
        if (stats === undefined || stats === null || !stats.isFile()) {
          // Still not found.
          tryDefaultFile(p, serveFileFunc, req, resp, log, count + 1);
        } else {
          // Found.
          serveFileFunc(p + "/" + defaultFile[count], req, resp, log);
        }
      });
    } else {
      // Finally, not found.
      sendError404(resp, log, "Found directionary, but not any default file");
    }
  };

  var buildFileResponseHeader = function(filePath, resp) {
    resp.setHeader('Content-Type', mime.lookup(filePath));

    if (cacheAllowed) {
      resp.setHeader('Cache-Control', 'max-age=' + cacheSecond);
    } else {
      resp.setHeader('Cache-Control', 'no-cache');    
    }
  }

  var serveFile = function(filePath, req, resp, log) {
    var fileStream = fs.createReadStream(filePath, {
      "flags" : "r",
    });

    buildFileResponseHeader(filePath, resp);
    resp.statusCode = log['resp_code'] = 200;
    fileStream.on("data", function(d) {
      resp.write(d);
    });
    fileStream.on("end", function() {
      resp.end();
    });
    logger(log);
  };

  // Build setting -------------------------------

  if (setting.hasOwnProperty("port")) {
    serverPort = setting['port'];
  }

  if (setting.hasOwnProperty("cache_allowed")) {
    cacheAllowed = !!setting['cache_allowed'];
  }

  if (setting.hasOwnProperty("cache_second")
      && typeof setting['cache_second'] == 'number') {
    cacheSecond = setting['cache_second'];
  }

  if (setting.hasOwnProperty("mime")) {
    mime.define(setting['mime']);
  }

  return function(req, resp) {
    var u = url.parse(req.url);
    var filePath = path.resolve(baseDir, u.pathname.slice(1));

    var log = {
      "req_path"    : u.pathname,
      "actual_path" : filePath
    };

    // Restrict in working directory.
    var relative = path.relative(baseDir, filePath);
    if (relative.length >= 2 && relative.slice(0, 2) == "..") {
      sendError404(resp, log, "Illegal path");
      return;
    }

    // Check target file. Exist, is a directory or not exist.
    fs.stat(filePath, function (err, stats) {
      if (stats === null || stats === undefined) {
        sendError404(resp, log, "Path not found");
      } else {
        if (stats.isFile()) {
          // Serve file
          serveFile(filePath, req, resp, log);
        } else if (stats.isDirectory()) {
          // Try default file
          tryDefaultFile(filePath, serveFile, req, resp, log);
        }
      }
    });
  };
};