H5P.JSXGraph/jsxgraph.js at main · jsxgraph/H5P.JSXGraph · GitHub

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var H5P = H5P || {};

H5P.JSXGraph = (function ($) {
  //   var $ = H5P.jQuery;
  //   this.$ = $(this);
  var useMathJax = true;

  var depurify = function (str) {
    return str.replace(/&#039;/g, "'").
      replace(/&quot;/g, '"').
      replace(/&lt;/g, '<').
      replace(/&gt;/g, '>').
      replace(/&amp;/g, '&');
  };

  /**
   * Remove unwanted code
   *
   * @param {String} str
   * @returns {String} purified string
   */
  var sanitizeJS = function(str) {
    return str.
      replace(/<script.*<\/script>/ig, '').
      replace(/<embed.*>/ig, '').
      replace(/<iframe.*>/ig, '').
      replace(/<link.*>/ig, '').
      replace(/<object.*>/ig, '').
      replace(/onclick/ig, '').
      replace(/javascript:/ig, '').
      replace(/document\.cookie/g, '').
      replace(/document\.write/g, '').
      replace(/charAt\(/g, '').
      replace(/fromCharCode\(/g, '').
      replace(/new Function\(/g, '').
      replace(/\s+eval\(/g, '');
  };

//   var jsEscape = function (str) {
//     return String(str).replace(/[^\w. ]/gi, function(c){
//        return '\\u'+('0000'+c.charCodeAt(0).toString(16)).slice(-4);
//     });
//   };

  /**
   * CSS properties for the style attribute of the JSXGraph div.
   * @param  {Object} options
   * @returns {String} String of CSS properties.
   */
  var getCSSForJXG = function (options) {
    var txt = '',
      res, w, h;

    if (false /*options.advanced.showFixedSize*/) {
      txt += 'width:' + options.advanced.width + '; ';
      txt += 'height:' + options.advanced.height + '; ';
    }
    else {
      // Use the new CSS property aspect-ratio.
      //txt += 'max-width:' + options.advanced.maxWidth + '; ';
      // txt += 'aspect-ratio:' + options.advanced.aspectRatio + '; ';
      // txt += 'margin: 0 auto;'
      // Use the old aspect-ratio hack.
      res = options.advanced.aspectRatio.match(/\w*(\d+)\w*\/\w*(\d+)\w*/);
      w = parseFloat(res[1]);
      h = parseFloat(res[2]);
      txt += 'height:0; padding-bottom:' + (100 * h / w) + '%;'
    }
    return txt;
  };

  /**
   * Compose the HTML head of the iframe
   * @param {String} libPath Path for JSXGraph js and CSS files
   * @param {String} csp String containing the content security policy
   * @param {String} secureJS Additional security
   * @returns {String} HTML text of the head part of the iframe
   */
  var getHead = function(libPath, csp, secureJS) {
    var headTxt = '<head><meta http-equiv="Content-Security-Policy" content="' + csp + '">';

    /**
     * Add JavaScript libraries and CSS files to the iFrame
     */
    if (useMathJax) {
        headTxt +=
        '<script src="' + libPath + '3rdparty/mathjax/es5/tex-chtml.js" type="text/javascript"></script>';
    }

    headTxt +=
      '<script src="' + libPath + 'jsxgraphcore.js" type="text/javascript"></script>' +
      '<link rel="stylesheet" href="' + libPath + 'h5p-jsxgraph.css" type="text/css">' +
      '<link rel="stylesheet" href="' + libPath + 'jsxgraph.css" type="text/css">';

    headTxt += secureJS;
    headTxt += '</head>';

    return headTxt;
  };

  /**
   * Build string consisting of the body of the iframe.
   * @param {String} divId
   * @param {Object} options
   * @returns
   */
  var getBody = function(divId, options) {
    var bodyTxt, outerPre, outerPost;

    // Set class on container to identify it as a JSXGraph construction.
    if (true /*!options.advanced.showFixedSize*/) {
      // Use the old aspect-ratio hack
      outerPre = '<div style="max-width:' + options.advanced.maxWidth + ';';
      outerPre += 'margin: 0 auto;';
      outerPre += '">'
      outerPost = '</div>';
    }
    else {
      outerPre = '';
      outerPost = '';
    }

    bodyTxt = '<body>' +
      // First text field
      '<div id="pre" class="h5p-jsxgraph-comment-post">' +
        options.commentPre +
      '</div>' +

      // JSXGraph div
      outerPre +
        '<div id="' + divId + '" class="jxgbox" ' +
        'style="' + getCSSForJXG(options) + '"' +
        '></div>' +
      outerPost +
      '' +

      // JavaScript code
      '<script type="text/javascript">' +
        sanitizeJS(depurify(options.code).replace(/BOARDID/g, "'" + divId + "'")) +
      '</script>' +

      // Second text field
      '<div id="post" class="h5p-jsxgraph-comment-post">'
        + options.commentPost +
      '</div>';

    bodyTxt += '</body>';

    return bodyTxt;
  };

  /**
   * Constructor function.
   */
  function C(options, id) {
    // Extend defaults with provided options

    this.options = $.extend(true, {}, {
      resizeSupported: true, // Unused?
      commentPre: 'BEFORE',
      commentPost: 'AFTER',
      advanced: {
        divId: '',
        // showFixedSize: true,
        width: '500px',
        height: '900px',
        maxWidth: '100%',
        aspectRatio: '1/1'
      },
      code: ''
    }, options);

    // Keep provided id.
    this.id = id;
  };

  /**
   * Attach function called by H5P framework to insert H5P content into
   * page
   *
   * @param {jQuery} $container
   */
  C.prototype.attach = function ($container) {
    var divId, csp, libPath, secureJS,
      doc, sandbox,
      options = this.options;

    /**
     * divId is the Id of the JSXGraph div
     */
    if (options.divId !== undefined && options.divId !== '') {
      // Take the supplied Id for the JSXGraph div.
      divId = options.divId;
    }
    else {
      // Choose random Id for the JSXGraph div.
      divId = 'jxg' + Math.random();
    }

    // libPath = "/sites/default/files/h5p/development/H5P.JSXGraph/";
    libPath = H5P.getLibraryPath('H5P.JSXGraph');
    // libPath = libPath.replace('libraries', 'development');
    libPath += '/';

    /**
     * Security: Add Content-Security-Policy to the head of the iframe
     *
     * Iframe can only connect to the hosting server.
     *
     */
    csp = 'navigate-to \'none\'; ' +
          'connect-src \'none\'; ' +
          'prefetch-src  \'none\'; ' +
          'worker-src  \'none\'; ' +
          'font-src    \'self\'; ' +
          'img-src     \'self\'; ' +
          'default-src \'self\'; ' +
          'style-src   \'unsafe-inline\' \'self\' ;' +
          'object-src  \'none\'; ' +
          'form-action \'none\'; ' +
          'frame-src   \'self\'; ' +
          'script-src  \'unsafe-inline\' \'self\';';

    /**
     * Additional security measure:
     * Block XHR and Websockets by disabling the objects
     * This should be redundant because of Content-Security-Policy.
     */
    secureJS = '<script type="text/javascript">' +
     'XMLHttpRequest = {};' +
     'WebSocket = {};' +
     'document.write = function() {};' + // It seems better to disable it instead of removing it from the code as above
     '</script>';

    /**
     * Attribute sandbox for the iframe.
     * See https://cloud.google.com/blog/products/data-analytics/iframe-sandbox-tutorial,
     * https://developer.mozilla.org/en-US/docs/Web/HTML/Element/iframe
     *
     * Allowed are:
     *   allow-same-origin	Allows the iframe content to be treated as being from the same origin
     *   allow-scripts	Allows to run scripts

     * Blocked are:
     *   allow-forms:	Allows form submission
     *   allow-modals: Allows to open modal windows
     *   allow-orientation-lock:	Allows to lock the screen orientation
     *   allow-pointer-lock:	Allows to use the Pointer Lock API
     *   allow-popups: Allows popups
     *   allow-popups-to-escape-sandbox:	Allows popups to open new windows without inheriting the sandboxing
     *   allow-presentation:	Allows to start a presentation session
     *   allow-top-navigation:	Allows the iframe content to navigate its top-level browsing context
     *   allow-top-navigation-by-user-: Allows the iframeactivation content to navigate its top-level browsing context, but only if initiated by user
     */
    sandbox = ' sandbox="allow-same-origin allow-scripts" ';

    if (false) {
      // Use H5P iframe
      $container.append(getHead(libPath, csp, secureJS) + getBody(divId, options));
    }
    else {
      // Create iframe from scratch
      $iframe = $('<iframe src="about:blank" scrolling="auto" frameborder="0"' + sandbox +  'class="h5p-iframe-content h5p-iframe-wrapper" />');

      $container.html('');
      $container.append($iframe);
      doc = $iframe.contents()[0];

      doc.open('text/html', 'replace');
      doc.writeln(getHead(libPath, csp, secureJS));
      doc.writeln(getBody(divId, options));
      doc.close();

      $iframe.css({ width: '100%', height: this.options.advanced.height});
    }
    $container.addClass("h5p-jsxgraph");
  };

  return C;
})(H5P.jQuery);