com.google.gwt.safehtml.shared.SafeUri Maven / Gradle / Ivy
/*
* Copyright 2011 Google Inc.
*
* 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.
*/
package com.google.gwt.safehtml.shared;
/**
* An object that implements this interface encapsulates a URI that is
* guaranteed to be safe to use (with respect to potential Cross-Site-Scripting
* vulnerabilities) in a URL context, for example in a URL-typed attribute in an
* HTML document.
*
*
* Note on usage: SafeUri should be used to ensure user input is not executed in
* the browser. SafeUri should not be used to sanitize input before sending it
* to the server: The server cannot rely on the type contract of SafeUri values
* received from clients, because a malicious client could provide maliciously
* crafted serialized forms of implementations of this type that violate the
* type contract.
*
*
* All implementing classes must maintain the class invariant (by design and
* implementation and/or convention of use), that invoking {@link #asString()}
* on any instance will return a string that is safe to assign to a URL-typed
* DOM or CSS property in a browser (or to use similarly in a "URL context"), in
* the sense that doing so must not cause unintended execution of script in the
* browser.
*
*
* In determining safety of a URL both the value itself as well as its
* provenance matter. An arbitrary URI, including e.g. a
* javascript: URI, can be deemed safe in the sense of this type's
* contract if it is entirely under the program's control (e.g., a string
* literal, {@see UriUtils#fromSafeConstant}).
*
*
* All implementations must implement equals() and hashCode() to behave
* consistently with the result of asString().equals() and asString.hashCode().
*
*
* Implementations must not return {@code null} from {@link #asString()}.
*
* @see UriUtils
*/
public interface SafeUri {
/**
* Returns this object's contained URI as a string.
*
*
* Based on this class' contract, the returned value will be non-null and a
* string that is safe to use in a URL context.
*
* @return the contents as a String
*/
String asString();
/**
* Compares this string to the specified object. Must be equal to
* asString().equals().
*
* @param anObject the object to compare to
*/
boolean equals(Object anObject);
/**
* Returns a hash code for this string. Must be equal to
* asString().hashCode().
*/
int hashCode();
}