// Copyright 2013 The Closure Library Authors. All Rights Reserved.
//
// 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.
/**
* @fileoverview Type-safe wrappers for unsafe DOM APIs.
*
* This file provides type-safe wrappers for DOM APIs that can result in
* cross-site scripting (XSS) vulnerabilities, if the API is supplied with
* untrusted (attacker-controlled) input. Instead of plain strings, the type
* safe wrappers consume values of types from the goog.html package whose
* contract promises that values are safe to use in the corresponding context.
*
* Hence, a program that exclusively uses the wrappers in this file (i.e., whose
* only reference to security-sensitive raw DOM APIs are in this file) is
* guaranteed to be free of XSS due to incorrect use of such DOM APIs (modulo
* correctness of code that produces values of the respective goog.html types,
* and absent code that violates type safety).
*
* For example, assigning to an element's .innerHTML property a string that is
* derived (even partially) from untrusted input typically results in an XSS
* vulnerability. The type-safe wrapper goog.html.setInnerHtml consumes a value
* of type goog.html.SafeHtml, whose contract states that using its values in a
* HTML context will not result in XSS. Hence a program that is free of direct
* assignments to any element's innerHTML property (with the exception of the
* assignment to .innerHTML in this file) is guaranteed to be free of XSS due to
* assignment of untrusted strings to the innerHTML property.
*/
goog.provide('goog.dom.safe');
goog.provide('goog.dom.safe.InsertAdjacentHtmlPosition');
goog.require('goog.asserts');
goog.require('goog.html.SafeHtml');
goog.require('goog.html.SafeUrl');
goog.require('goog.html.TrustedResourceUrl');
goog.require('goog.string');
goog.require('goog.string.Const');
/** @enum {string} */
goog.dom.safe.InsertAdjacentHtmlPosition = {
AFTERBEGIN: 'afterbegin',
AFTEREND: 'afterend',
BEFOREBEGIN: 'beforebegin',
BEFOREEND: 'beforeend'
};
/**
* Inserts known-safe HTML into a Node, at the specified position.
* @param {!Node} node The node on which to call insertAdjacentHTML.
* @param {!goog.dom.safe.InsertAdjacentHtmlPosition} position Position where
* to insert the HTML.
* @param {!goog.html.SafeHtml} html The known-safe HTML to insert.
*/
goog.dom.safe.insertAdjacentHtml = function(node, position, html) {
node.insertAdjacentHTML(position, goog.html.SafeHtml.unwrap(html));
};
/**
* Assigns known-safe HTML to an element's innerHTML property.
* @param {!Element} elem The element whose innerHTML is to be assigned to.
* @param {!goog.html.SafeHtml} html The known-safe HTML to assign.
*/
goog.dom.safe.setInnerHtml = function(elem, html) {
elem.innerHTML = goog.html.SafeHtml.unwrap(html);
};
/**
* Assigns known-safe HTML to an element's outerHTML property.
* @param {!Element} elem The element whose outerHTML is to be assigned to.
* @param {!goog.html.SafeHtml} html The known-safe HTML to assign.
*/
goog.dom.safe.setOuterHtml = function(elem, html) {
elem.outerHTML = goog.html.SafeHtml.unwrap(html);
};
/**
* Writes known-safe HTML to a document.
* @param {!Document} doc The document to be written to.
* @param {!goog.html.SafeHtml} html The known-safe HTML to assign.
*/
goog.dom.safe.documentWrite = function(doc, html) {
doc.write(goog.html.SafeHtml.unwrap(html));
};
/**
* Safely assigns a URL to an anchor element's href property.
*
* If url is of type goog.html.SafeUrl, its value is unwrapped and assigned to
* anchor's href property. If url is of type string however, it is first
* sanitized using goog.html.SafeUrl.sanitize.
*
* Example usage:
* goog.dom.safe.setAnchorHref(anchorEl, url);
* which is a safe alternative to
* anchorEl.href = url;
* The latter can result in XSS vulnerabilities if url is a
* user-/attacker-controlled value.
*
* @param {!HTMLAnchorElement} anchor The anchor element whose href property
* is to be assigned to.
* @param {string|!goog.html.SafeUrl} url The URL to assign.
* @see goog.html.SafeUrl#sanitize
*/
goog.dom.safe.setAnchorHref = function(anchor, url) {
/** @type {!goog.html.SafeUrl} */
var safeUrl;
if (url instanceof goog.html.SafeUrl) {
safeUrl = url;
} else {
safeUrl = goog.html.SafeUrl.sanitize(url);
}
anchor.href = goog.html.SafeUrl.unwrap(safeUrl);
};
/**
* Safely assigns a URL to an embed element's src property.
*
* Example usage:
* goog.dom.safe.setEmbedSrc(embedEl, url);
* which is a safe alternative to
* embedEl.src = url;
* The latter can result in loading untrusted code unless it is ensured that
* the URL refers to a trustworthy resource.
*
* @param {!HTMLEmbedElement} embed The embed element whose src property
* is to be assigned to.
* @param {!goog.html.TrustedResourceUrl} url The URL to assign.
*/
goog.dom.safe.setEmbedSrc = function(embed, url) {
embed.src = goog.html.TrustedResourceUrl.unwrap(url);
};
/**
* Safely assigns a URL to a frame element's src property.
*
* Example usage:
* goog.dom.safe.setFrameSrc(frameEl, url);
* which is a safe alternative to
* frameEl.src = url;
* The latter can result in loading untrusted code unless it is ensured that
* the URL refers to a trustworthy resource.
*
* @param {!HTMLFrameElement} frame The frame element whose src property
* is to be assigned to.
* @param {!goog.html.TrustedResourceUrl} url The URL to assign.
*/
goog.dom.safe.setFrameSrc = function(frame, url) {
frame.src = goog.html.TrustedResourceUrl.unwrap(url);
};
/**
* Safely assigns a URL to an iframe element's src property.
*
* Example usage:
* goog.dom.safe.setIframeSrc(iframeEl, url);
* which is a safe alternative to
* iframeEl.src = url;
* The latter can result in loading untrusted code unless it is ensured that
* the URL refers to a trustworthy resource.
*
* @param {!HTMLIFrameElement} iframe The iframe element whose src property
* is to be assigned to.
* @param {!goog.html.TrustedResourceUrl} url The URL to assign.
*/
goog.dom.safe.setIframeSrc = function(iframe, url) {
iframe.src = goog.html.TrustedResourceUrl.unwrap(url);
};
/**
* Safely sets a link element's href and rel properties. Whether or not
* the URL assigned to href has to be a goog.html.TrustedResourceUrl
* depends on the value of the rel property. If rel contains "stylesheet"
* then a TrustedResourceUrl is required.
*
* Example usage:
* goog.dom.safe.setLinkHrefAndRel(linkEl, url, 'stylesheet');
* which is a safe alternative to
* linkEl.rel = 'stylesheet';
* linkEl.href = url;
* The latter can result in loading untrusted code unless it is ensured that
* the URL refers to a trustworthy resource.
*
* @param {!HTMLLinkElement} link The link element whose href property
* is to be assigned to.
* @param {string|!goog.html.SafeUrl|!goog.html.TrustedResourceUrl} url The URL
* to assign to the href property. Must be a TrustedResourceUrl if the
* value assigned to rel contains "stylesheet". A string value is
* sanitized with goog.html.SafeUrl.sanitize.
* @param {string} rel The value to assign to the rel property.
* @throws {Error} if rel contains "stylesheet" and url is not a
* TrustedResourceUrl
* @see goog.html.SafeUrl#sanitize
*/
goog.dom.safe.setLinkHrefAndRel = function(link, url, rel) {
link.rel = rel;
if (goog.string.caseInsensitiveContains(rel, 'stylesheet')) {
goog.asserts.assert(
url instanceof goog.html.TrustedResourceUrl,
'URL must be TrustedResourceUrl because "rel" contains "stylesheet"');
link.href = goog.html.TrustedResourceUrl.unwrap(url);
} else if (url instanceof goog.html.TrustedResourceUrl) {
link.href = goog.html.TrustedResourceUrl.unwrap(url);
} else if (url instanceof goog.html.SafeUrl) {
link.href = goog.html.SafeUrl.unwrap(url);
} else { // string
// SafeUrl.sanitize must return legitimate SafeUrl when passed a string.
link.href = goog.html.SafeUrl.sanitize(url).getTypedStringValue();
}
};
/**
* Safely assigns a URL to an object element's data property.
*
* Example usage:
* goog.dom.safe.setObjectData(objectEl, url);
* which is a safe alternative to
* objectEl.data = url;
* The latter can result in loading untrusted code unless setit is ensured that
* the URL refers to a trustworthy resource.
*
* @param {!HTMLObjectElement} object The object element whose data property
* is to be assigned to.
* @param {!goog.html.TrustedResourceUrl} url The URL to assign.
*/
goog.dom.safe.setObjectData = function(object, url) {
object.data = goog.html.TrustedResourceUrl.unwrap(url);
};
/**
* Safely assigns a URL to an iframe element's src property.
*
* Example usage:
* goog.dom.safe.setScriptSrc(scriptEl, url);
* which is a safe alternative to
* scriptEl.src = url;
* The latter can result in loading untrusted code unless it is ensured that
* the URL refers to a trustworthy resource.
*
* @param {!HTMLScriptElement} script The script element whose src property
* is to be assigned to.
* @param {!goog.html.TrustedResourceUrl} url The URL to assign.
*/
goog.dom.safe.setScriptSrc = function(script, url) {
script.src = goog.html.TrustedResourceUrl.unwrap(url);
};
/**
* Safely assigns a URL to a Location object's href property.
*
* If url is of type goog.html.SafeUrl, its value is unwrapped and assigned to
* loc's href property. If url is of type string however, it is first sanitized
* using goog.html.SafeUrl.sanitize.
*
* Example usage:
* goog.dom.safe.setLocationHref(document.location, redirectUrl);
* which is a safe alternative to
* document.location.href = redirectUrl;
* The latter can result in XSS vulnerabilities if redirectUrl is a
* user-/attacker-controlled value.
*
* @param {!Location} loc The Location object whose href property is to be
* assigned to.
* @param {string|!goog.html.SafeUrl} url The URL to assign.
* @see goog.html.SafeUrl#sanitize
*/
goog.dom.safe.setLocationHref = function(loc, url) {
/** @type {!goog.html.SafeUrl} */
var safeUrl;
if (url instanceof goog.html.SafeUrl) {
safeUrl = url;
} else {
safeUrl = goog.html.SafeUrl.sanitize(url);
}
loc.href = goog.html.SafeUrl.unwrap(safeUrl);
};
/**
* Safely opens a URL in a new window (via window.open).
*
* If url is of type goog.html.SafeUrl, its value is unwrapped and passed in to
* window.open. If url is of type string however, it is first sanitized
* using goog.html.SafeUrl.sanitize.
*
* Note that this function does not prevent leakages via the referer that is
* sent by window.open. It is advised to only use this to open 1st party URLs.
*
* Example usage:
* goog.dom.safe.openInWindow(url);
* which is a safe alternative to
* window.open(url);
* The latter can result in XSS vulnerabilities if redirectUrl is a
* user-/attacker-controlled value.
*
* @param {string|!goog.html.SafeUrl} url The URL to open.
* @param {Window=} opt_openerWin Window of which to call the .open() method.
* Defaults to the global window.
* @param {!goog.string.Const=} opt_name Name of the window to open in. Can be
* _top, etc as allowed by window.open().
* @param {string=} opt_specs Comma-separated list of specifications, same as
* in window.open().
* @param {boolean=} opt_replace Whether to replace the current entry in browser
* history, same as in window.open().
* @return {Window} Window the url was opened in.
*/
goog.dom.safe.openInWindow = function(
url, opt_openerWin, opt_name, opt_specs, opt_replace) {
/** @type {!goog.html.SafeUrl} */
var safeUrl;
if (url instanceof goog.html.SafeUrl) {
safeUrl = url;
} else {
safeUrl = goog.html.SafeUrl.sanitize(url);
}
var win = opt_openerWin || window;
return win.open(goog.html.SafeUrl.unwrap(safeUrl),
// If opt_name is undefined, simply passing that in to open() causes IE to
// reuse the current window instead of opening a new one. Thus we pass ''
// in instead, which according to spec opens a new window. See
// https://html.spec.whatwg.org/multipage/browsers.html#dom-open .
opt_name ? goog.string.Const.unwrap(opt_name) : '',
opt_specs, opt_replace);
};
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