413 lines
15 KiB
JavaScript
413 lines
15 KiB
JavaScript
// 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 The SafeUrl type and its builders.
|
|
*
|
|
* TODO(xtof): Link to document stating type contract.
|
|
*/
|
|
|
|
goog.provide('goog.html.SafeUrl');
|
|
|
|
goog.require('goog.asserts');
|
|
goog.require('goog.fs.url');
|
|
goog.require('goog.i18n.bidi.Dir');
|
|
goog.require('goog.i18n.bidi.DirectionalString');
|
|
goog.require('goog.string');
|
|
goog.require('goog.string.Const');
|
|
goog.require('goog.string.TypedString');
|
|
|
|
|
|
|
|
/**
|
|
* A string that is safe to use in URL context in DOM APIs and HTML documents.
|
|
*
|
|
* A SafeUrl is a string-like object that carries the security type contract
|
|
* that its value as a string will not cause untrusted script execution
|
|
* when evaluated as a hyperlink URL in a browser.
|
|
*
|
|
* Values of this type are guaranteed to be safe to use in URL/hyperlink
|
|
* contexts, such as, assignment to URL-valued DOM properties, or
|
|
* interpolation into a HTML template in URL context (e.g., inside a href
|
|
* attribute), in the sense that the use will not result in a
|
|
* Cross-Site-Scripting vulnerability.
|
|
*
|
|
* Note that, as documented in {@code goog.html.SafeUrl.unwrap}, this type's
|
|
* contract does not guarantee that instances are safe to interpolate into HTML
|
|
* without appropriate escaping.
|
|
*
|
|
* Note also that this type's contract does not imply any guarantees regarding
|
|
* the resource the URL refers to. In particular, SafeUrls are <b>not</b>
|
|
* safe to use in a context where the referred-to resource is interpreted as
|
|
* trusted code, e.g., as the src of a script tag.
|
|
*
|
|
* Instances of this type must be created via the factory methods
|
|
* ({@code goog.html.SafeUrl.fromConstant}, {@code goog.html.SafeUrl.sanitize}),
|
|
* etc and not by invoking its constructor. The constructor intentionally
|
|
* takes no parameters and the type is immutable; hence only a default instance
|
|
* corresponding to the empty string can be obtained via constructor invocation.
|
|
*
|
|
* @see goog.html.SafeUrl#fromConstant
|
|
* @see goog.html.SafeUrl#from
|
|
* @see goog.html.SafeUrl#sanitize
|
|
* @constructor
|
|
* @final
|
|
* @struct
|
|
* @implements {goog.i18n.bidi.DirectionalString}
|
|
* @implements {goog.string.TypedString}
|
|
*/
|
|
goog.html.SafeUrl = function() {
|
|
/**
|
|
* The contained value of this SafeUrl. The field has a purposely ugly
|
|
* name to make (non-compiled) code that attempts to directly access this
|
|
* field stand out.
|
|
* @private {string}
|
|
*/
|
|
this.privateDoNotAccessOrElseSafeHtmlWrappedValue_ = '';
|
|
|
|
/**
|
|
* A type marker used to implement additional run-time type checking.
|
|
* @see goog.html.SafeUrl#unwrap
|
|
* @const
|
|
* @private
|
|
*/
|
|
this.SAFE_URL_TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ =
|
|
goog.html.SafeUrl.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_;
|
|
};
|
|
|
|
|
|
/**
|
|
* The innocuous string generated by goog.html.SafeUrl.sanitize when passed
|
|
* an unsafe URL.
|
|
*
|
|
* about:invalid is registered in
|
|
* http://www.w3.org/TR/css3-values/#about-invalid.
|
|
* http://tools.ietf.org/html/rfc6694#section-2.2.1 permits about URLs to
|
|
* contain a fragment, which is not to be considered when determining if an
|
|
* about URL is well-known.
|
|
*
|
|
* Using about:invalid seems preferable to using a fixed data URL, since
|
|
* browsers might choose to not report CSP violations on it, as legitimate
|
|
* CSS function calls to attr() can result in this URL being produced. It is
|
|
* also a standard URL which matches exactly the semantics we need:
|
|
* "The about:invalid URI references a non-existent document with a generic
|
|
* error condition. It can be used when a URI is necessary, but the default
|
|
* value shouldn't be resolveable as any type of document".
|
|
*
|
|
* @const {string}
|
|
*/
|
|
goog.html.SafeUrl.INNOCUOUS_STRING = 'about:invalid#zClosurez';
|
|
|
|
|
|
/**
|
|
* @override
|
|
* @const
|
|
*/
|
|
goog.html.SafeUrl.prototype.implementsGoogStringTypedString = true;
|
|
|
|
|
|
/**
|
|
* Returns this SafeUrl's value a string.
|
|
*
|
|
* IMPORTANT: In code where it is security relevant that an object's type is
|
|
* indeed {@code SafeUrl}, use {@code goog.html.SafeUrl.unwrap} instead of this
|
|
* method. If in doubt, assume that it's security relevant. In particular, note
|
|
* that goog.html functions which return a goog.html type do not guarantee that
|
|
* the returned instance is of the right type. For example:
|
|
*
|
|
* <pre>
|
|
* var fakeSafeHtml = new String('fake');
|
|
* fakeSafeHtml.__proto__ = goog.html.SafeHtml.prototype;
|
|
* var newSafeHtml = goog.html.SafeHtml.htmlEscape(fakeSafeHtml);
|
|
* // newSafeHtml is just an alias for fakeSafeHtml, it's passed through by
|
|
* // goog.html.SafeHtml.htmlEscape() as fakeSafeHtml instanceof
|
|
* // goog.html.SafeHtml.
|
|
* </pre>
|
|
*
|
|
* IMPORTANT: The guarantees of the SafeUrl type contract only extend to the
|
|
* behavior of browsers when interpreting URLs. Values of SafeUrl objects MUST
|
|
* be appropriately escaped before embedding in a HTML document. Note that the
|
|
* required escaping is context-sensitive (e.g. a different escaping is
|
|
* required for embedding a URL in a style property within a style
|
|
* attribute, as opposed to embedding in a href attribute).
|
|
*
|
|
* @see goog.html.SafeUrl#unwrap
|
|
* @override
|
|
*/
|
|
goog.html.SafeUrl.prototype.getTypedStringValue = function() {
|
|
return this.privateDoNotAccessOrElseSafeHtmlWrappedValue_;
|
|
};
|
|
|
|
|
|
/**
|
|
* @override
|
|
* @const
|
|
*/
|
|
goog.html.SafeUrl.prototype.implementsGoogI18nBidiDirectionalString = true;
|
|
|
|
|
|
/**
|
|
* Returns this URLs directionality, which is always {@code LTR}.
|
|
* @override
|
|
*/
|
|
goog.html.SafeUrl.prototype.getDirection = function() {
|
|
return goog.i18n.bidi.Dir.LTR;
|
|
};
|
|
|
|
|
|
if (goog.DEBUG) {
|
|
/**
|
|
* Returns a debug string-representation of this value.
|
|
*
|
|
* To obtain the actual string value wrapped in a SafeUrl, use
|
|
* {@code goog.html.SafeUrl.unwrap}.
|
|
*
|
|
* @see goog.html.SafeUrl#unwrap
|
|
* @override
|
|
*/
|
|
goog.html.SafeUrl.prototype.toString = function() {
|
|
return 'SafeUrl{' + this.privateDoNotAccessOrElseSafeHtmlWrappedValue_ +
|
|
'}';
|
|
};
|
|
}
|
|
|
|
|
|
/**
|
|
* Performs a runtime check that the provided object is indeed a SafeUrl
|
|
* object, and returns its value.
|
|
*
|
|
* IMPORTANT: The guarantees of the SafeUrl type contract only extend to the
|
|
* behavior of browsers when interpreting URLs. Values of SafeUrl objects MUST
|
|
* be appropriately escaped before embedding in a HTML document. Note that the
|
|
* required escaping is context-sensitive (e.g. a different escaping is
|
|
* required for embedding a URL in a style property within a style
|
|
* attribute, as opposed to embedding in a href attribute).
|
|
*
|
|
* @param {!goog.html.SafeUrl} safeUrl The object to extract from.
|
|
* @return {string} The SafeUrl object's contained string, unless the run-time
|
|
* type check fails. In that case, {@code unwrap} returns an innocuous
|
|
* string, or, if assertions are enabled, throws
|
|
* {@code goog.asserts.AssertionError}.
|
|
*/
|
|
goog.html.SafeUrl.unwrap = function(safeUrl) {
|
|
// Perform additional Run-time type-checking to ensure that safeUrl is indeed
|
|
// an instance of the expected type. This provides some additional protection
|
|
// against security bugs due to application code that disables type checks.
|
|
// Specifically, the following checks are performed:
|
|
// 1. The object is an instance of the expected type.
|
|
// 2. The object is not an instance of a subclass.
|
|
// 3. The object carries a type marker for the expected type. "Faking" an
|
|
// object requires a reference to the type marker, which has names intended
|
|
// to stand out in code reviews.
|
|
if (safeUrl instanceof goog.html.SafeUrl &&
|
|
safeUrl.constructor === goog.html.SafeUrl &&
|
|
safeUrl.SAFE_URL_TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ ===
|
|
goog.html.SafeUrl.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_) {
|
|
return safeUrl.privateDoNotAccessOrElseSafeHtmlWrappedValue_;
|
|
} else {
|
|
goog.asserts.fail('expected object of type SafeUrl, got \'' +
|
|
safeUrl + '\' of type ' + goog.typeOf(safeUrl));
|
|
return 'type_error:SafeUrl';
|
|
}
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a SafeUrl object from a compile-time constant string.
|
|
*
|
|
* Compile-time constant strings are inherently program-controlled and hence
|
|
* trusted.
|
|
*
|
|
* @param {!goog.string.Const} url A compile-time-constant string from which to
|
|
* create a SafeUrl.
|
|
* @return {!goog.html.SafeUrl} A SafeUrl object initialized to {@code url}.
|
|
*/
|
|
goog.html.SafeUrl.fromConstant = function(url) {
|
|
return goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse(
|
|
goog.string.Const.unwrap(url));
|
|
};
|
|
|
|
|
|
/**
|
|
* A pattern that matches Blob or data types that can have SafeUrls created
|
|
* from URL.createObjectURL(blob) or via a data: URI. Only matches image and
|
|
* video types, currently.
|
|
* @const
|
|
* @private
|
|
*/
|
|
goog.html.SAFE_MIME_TYPE_PATTERN_ =
|
|
/^(?:image\/(?:bmp|gif|jpeg|jpg|png|tiff|webp)|video\/(?:mpeg|mp4|ogg|webm))$/i;
|
|
|
|
|
|
/**
|
|
* Creates a SafeUrl wrapping a blob URL for the given {@code blob}.
|
|
*
|
|
* The blob URL is created with {@code URL.createObjectURL}. If the MIME type
|
|
* for {@code blob} is not of a known safe image or video MIME type, then the
|
|
* SafeUrl will wrap {@link #INNOCUOUS_STRING}.
|
|
*
|
|
* @see http://www.w3.org/TR/FileAPI/#url
|
|
* @param {!Blob} blob
|
|
* @return {!goog.html.SafeUrl} The blob URL, or an innocuous string wrapped
|
|
* as a SafeUrl.
|
|
*/
|
|
goog.html.SafeUrl.fromBlob = function(blob) {
|
|
var url = goog.html.SAFE_MIME_TYPE_PATTERN_.test(blob.type) ?
|
|
goog.fs.url.createObjectUrl(blob) :
|
|
goog.html.SafeUrl.INNOCUOUS_STRING;
|
|
return goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse(url);
|
|
};
|
|
|
|
|
|
/**
|
|
* Matches a base-64 data URL, with the first match group being the MIME type.
|
|
* @const
|
|
* @private
|
|
*/
|
|
goog.html.DATA_URL_PATTERN_ = /^data:([^;,]*);base64,[a-z0-9+\/]+=*$/i;
|
|
|
|
|
|
/**
|
|
* Creates a SafeUrl wrapping a data: URL, after validating it matches a
|
|
* known-safe image or video MIME type.
|
|
*
|
|
* @param {string} dataUrl A valid base64 data URL with one of the whitelisted
|
|
* image or video MIME types.
|
|
* @return {!goog.html.SafeUrl} A matching safe URL, or {@link INNOCUOUS_STRING}
|
|
* wrapped as a SafeUrl if it does not pass.
|
|
*/
|
|
goog.html.SafeUrl.fromDataUrl = function(dataUrl) {
|
|
// There's a slight risk here that a browser sniffs the content type if it
|
|
// doesn't know the MIME type and executes HTML within the data: URL. For this
|
|
// to cause XSS it would also have to execute the HTML in the same origin
|
|
// of the page with the link. It seems unlikely that both of these will
|
|
// happen, particularly in not really old IEs.
|
|
var match = dataUrl.match(goog.html.DATA_URL_PATTERN_);
|
|
var valid = match && goog.html.SAFE_MIME_TYPE_PATTERN_.test(match[1]);
|
|
return goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse(
|
|
valid ? dataUrl : goog.html.SafeUrl.INNOCUOUS_STRING);
|
|
};
|
|
|
|
|
|
/**
|
|
* Creates a SafeUrl wrapping a tel: URL.
|
|
*
|
|
* @param {string} telUrl A tel URL.
|
|
* @return {!goog.html.SafeUrl} A matching safe URL, or {@link INNOCUOUS_STRING}
|
|
* wrapped as a SafeUrl if it does not pass.
|
|
*/
|
|
goog.html.SafeUrl.fromTelUrl = function(telUrl) {
|
|
// There's a risk that a tel: URL could immediately place a call once
|
|
// clicked, without requiring user confirmation. For that reason it is
|
|
// handled in this separate function.
|
|
if (!goog.string.caseInsensitiveStartsWith(telUrl, 'tel:')) {
|
|
telUrl = goog.html.SafeUrl.INNOCUOUS_STRING;
|
|
}
|
|
return goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse(
|
|
telUrl);
|
|
};
|
|
|
|
|
|
/**
|
|
* A pattern that recognizes a commonly useful subset of URLs that satisfy
|
|
* the SafeUrl contract.
|
|
*
|
|
* This regular expression matches a subset of URLs that will not cause script
|
|
* execution if used in URL context within a HTML document. Specifically, this
|
|
* regular expression matches if (comment from here on and regex copied from
|
|
* Soy's EscapingConventions):
|
|
* (1) Either a protocol in a whitelist (http, https, mailto or ftp).
|
|
* (2) or no protocol. A protocol must be followed by a colon. The below
|
|
* allows that by allowing colons only after one of the characters [/?#].
|
|
* A colon after a hash (#) must be in the fragment.
|
|
* Otherwise, a colon after a (?) must be in a query.
|
|
* Otherwise, a colon after a single solidus (/) must be in a path.
|
|
* Otherwise, a colon after a double solidus (//) must be in the authority
|
|
* (before port).
|
|
*
|
|
* The pattern disallows &, used in HTML entity declarations before
|
|
* one of the characters in [/?#]. This disallows HTML entities used in the
|
|
* protocol name, which should never happen, e.g. "http" for "http".
|
|
* It also disallows HTML entities in the first path part of a relative path,
|
|
* e.g. "foo<bar/baz". Our existing escaping functions should not produce
|
|
* that. More importantly, it disallows masking of a colon,
|
|
* e.g. "javascript:...".
|
|
*
|
|
* @private
|
|
* @const {!RegExp}
|
|
*/
|
|
goog.html.SAFE_URL_PATTERN_ =
|
|
/^(?:(?:https?|mailto|ftp):|[^&:/?#]*(?:[/?#]|$))/i;
|
|
|
|
|
|
/**
|
|
* Creates a SafeUrl object from {@code url}. If {@code url} is a
|
|
* goog.html.SafeUrl then it is simply returned. Otherwise the input string is
|
|
* validated to match a pattern of commonly used safe URLs.
|
|
*
|
|
* {@code url} may be a URL with the http, https, mailto or ftp scheme,
|
|
* or a relative URL (i.e., a URL without a scheme; specifically, a
|
|
* scheme-relative, absolute-path-relative, or path-relative URL).
|
|
*
|
|
* @see http://url.spec.whatwg.org/#concept-relative-url
|
|
* @param {string|!goog.string.TypedString} url The URL to validate.
|
|
* @return {!goog.html.SafeUrl} The validated URL, wrapped as a SafeUrl.
|
|
*/
|
|
goog.html.SafeUrl.sanitize = function(url) {
|
|
if (url instanceof goog.html.SafeUrl) {
|
|
return url;
|
|
} else if (url.implementsGoogStringTypedString) {
|
|
url = url.getTypedStringValue();
|
|
} else {
|
|
url = String(url);
|
|
}
|
|
if (!goog.html.SAFE_URL_PATTERN_.test(url)) {
|
|
url = goog.html.SafeUrl.INNOCUOUS_STRING;
|
|
}
|
|
return goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse(url);
|
|
};
|
|
|
|
|
|
/**
|
|
* Type marker for the SafeUrl type, used to implement additional run-time
|
|
* type checking.
|
|
* @const {!Object}
|
|
* @private
|
|
*/
|
|
goog.html.SafeUrl.TYPE_MARKER_GOOG_HTML_SECURITY_PRIVATE_ = {};
|
|
|
|
|
|
/**
|
|
* Package-internal utility method to create SafeUrl instances.
|
|
*
|
|
* @param {string} url The string to initialize the SafeUrl object with.
|
|
* @return {!goog.html.SafeUrl} The initialized SafeUrl object.
|
|
* @package
|
|
*/
|
|
goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse = function(
|
|
url) {
|
|
var safeUrl = new goog.html.SafeUrl();
|
|
safeUrl.privateDoNotAccessOrElseSafeHtmlWrappedValue_ = url;
|
|
return safeUrl;
|
|
};
|
|
|
|
|
|
/**
|
|
* A SafeUrl corresponding to the special about:blank url.
|
|
* @const {!goog.html.SafeUrl}
|
|
*/
|
|
goog.html.SafeUrl.ABOUT_BLANK =
|
|
goog.html.SafeUrl.createSafeUrlSecurityPrivateDoNotAccessOrElse(
|
|
'about:blank');
|