WebFund 2014W: Assignment 4

Solutions for this assignment are available here. Also a partial solution with a different approach for jade is here.

In this assignment you are to examine, modify, and answer questions regarding the tinywebserver.js sample node application. The single file of this application is also listed below.

Please submit your answers as a single JavaScript file called "<username>-comp2406-assign4.js" (where username is your MyCarletonOne username), where this file is your modified version of tinywebserver.js. Make sure to include the text "COMP 2406 Assignment 4", your name, student number, and the date in the comments at the very top of the file. If you have trouble submitting your program to cuLearn, add a .txt extension to the file.

Note that if you need additional files to implement the 404 page, you may instead upload a zip file.

Questions

There are six questions below with a total of 20 points. Please answer all questions.

1. [2] Change the application so that it listens to the port specified by the PORT environment variable if it is defined. If no PORT environment variable is defined, the server should listen on port 3000.
2. [2] Change the server to serve files from $HOME/public_html rather than the current directory, where $HOME is the home directory of the current user. Thus if you are logged in as the user student, the server should serve files from /home/student/public_html.
3. [4] Change tinywebserver.js so it returns a simple HTML error page in response to 404 errors (page not found). Please be creative in your choice of error page.
4. [4] Using the jade module, change the server so that files that end in .jade are turned into HTML files before being returned to the client. Make sure jade files can include other jade files in the same directory (e.g., by using extends in the way we have in other programs this semester). Note the MIME type of your response should be text/html.
5. [4] Using the querystring module, make it so that arguments passed in the URL are passed on to the jade file. For example, http://localhost:3000/index.jade?title=MyApp should render index.jade with the value of title being "MyApp".
6. [4] Change the program so that accesses to directories will return the (properly rendered) contents of index.jade if no index.html file exists.

Code

// tinywebserver.js
//
// A modification of Rod Waldhoff's tiny node.js webserver
// original written in coffeescript
// simplified and made more native-ish by Anil Somayaji
// March 19, 2014
//
// original headers of coffeescript version:
//
// A simple static-file web server implemented as a stand-alone
// Node.js/CoffeeScript app.
//---------------------------------------------------------------------
// For more information, see:
// <https://github.com/rodw/tiny-node.js-webserver>
//---------------------------------------------------------------------
// This program is distributed under the "MIT License".
// (See <http://www.opensource.org/licenses/mit-license.php>.)
//---------------------------------------------------------------------
// Copyright (c) 2012 Rodney Waldhoff
//
// Permission is hereby granted, free of charge, to any person
// obtaining a copy of this software and associated documentation
// files (the "Software"), to deal in the Software without restriction,
// including without limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of the Software,
// and to permit persons to whom the Software is furnished to do so,
// subject to the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
// OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
// BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
// ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
// CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
//---------------------------------------------------------------------

var path = require('path');
var http = require('http');
var fs = require('fs');

var MIME_TYPES = {
    'css': 'text/css',
    'gif': 'image/gif',
    'htm': 'text/html',
    'html': 'text/html',
    'ico': 'image/x-icon',
    'jpeg': 'image/jpeg',
    'jpg': 'image/jpeg',
    'js': 'text/javascript',
    'json': 'application/json',
    'png': 'image/png',
    'txt': 'text/text'
};

var options = {
    host: 'localhost',
    port: 8080,
    index: 'index.html',
    docroot: '.'
};

var get_mime = function(filename) {
    var ext, type;
    for (ext in MIME_TYPES) {
        type = MIME_TYPES[ext];
        if (filename.indexOf(ext, filename.length - ext.length) !== -1) {
            return type;
        }
    }
    return null;
};


var respond = function(request, response, status, content, content_type) {
    if (!status) {
        status = 200;
    }

    if (!content_type) {
        content_type = 'text/plain';
    }
    console.log("" + status + "\t" +
                request.method + "\t" + request.url);
    response.writeHead(status, {
        "Content-Type": content_type
    });
    if (content) {
        response.write(content);
    }
    return response.end();
};

var serve_file = function(request, response, requestpath) {
    return fs.readFile(requestpath, function(error, content) {
        if (error != null) {
            console.error("ERROR: Encountered error while processing " +
                          request.method + " of \"" + request.url + 
                          "\".", error);
            return respond(request, response, 500);
        } else {
            return respond(request, response, 200, 
                           content, get_mime(requestpath));
        }
    });
};


var return_index = function(request, response, requestpath)  {

    var exists_callback = function(file_exists) {
        if (file_exists) {
            return serve_file(request, response, requestpath);
        } else {
            return respond(request, response, 404);
        }
    }
    
    if (requestpath.substr(-1) !== '/') {
        requestpath += "/";
    }
    requestpath += options.index;
    return fs.exists(requestpath, exists_callback);
}

var request_handler = function(request, response) {
    var requestpath;

    if (request.url.match(/((\.|%2E|%2e)(\.|%2E|%2e))|(~|%7E|%7e)/) != null) {
        console.warn("WARNING: " + request.method +
                     " of \"" + request.url + 
                     "\" rejected as insecure.");
        return respond(request, response, 403);
    } else {
        requestpath = path.normalize(path.join(options.docroot, request.url));
        return fs.exists(requestpath, function(file_exists) {
            if (file_exists) {
                return fs.stat(requestpath, function(err, stat) {
                    if (err != null) {
                        console.error("ERROR: Encountered error calling" +
                                      "fs.stat on \"" + requestpath + 
                                      "\" while processing " + 
                                      request.method + " of \"" + 
                                      request.url + "\".", err);
                        return respond(request, response, 500);
                    } else {
                        if ((stat != null) && stat.isDirectory()) {
                            return return_index(request, response, requestpath);
                        } else {
                            return serve_file(request, response, requestpath);
                        }
                    }
                });
            } else {
                return respond(request, response, 404);
            }
        });
    }
};

var server = http.createServer(request_handler);

server.listen(options.port, options.host, function() {
    return console.log("Server listening at http://" +
                       options.host + ":" + options.port + "/");
});