| // 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.require('goog.html.SafeHtml'); |
| goog.require('goog.html.SafeUrl'); |
| |
| |
| /** |
| * 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 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); |
| }; |