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/*
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
*
* Copyright (c) 2010-2013 Oracle and/or its affiliates. All rights reserved.
*
* The contents of this file are subject to the terms of either the GNU
* General Public License Version 2 only ("GPL") or the Common Development
* and Distribution License("CDDL") (collectively, the "License"). You
* may not use this file except in compliance with the License. You can
* obtain a copy of the License at
* https://glassfish.dev.java.net/public/CDDL+GPL_1_1.html
* or packager/legal/LICENSE.txt. See the License for the specific
* language governing permissions and limitations under the License.
*
* When distributing the software, include this License Header Notice in each
* file and include the License file at packager/legal/LICENSE.txt.
*
* GPL Classpath Exception:
* Oracle designates this particular file as subject to the "Classpath"
* exception as provided by Oracle in the GPL Version 2 section of the License
* file that accompanied this code.
*
* Modifications:
* If applicable, add the following below the License Header, with the fields
* enclosed by brackets [] replaced by your own identifying information:
* "Portions Copyright [year] [name of copyright owner]"
*
* Contributor(s):
* If you wish your version of this file to be governed by only the CDDL or
* only the GPL Version 2, indicate your decision by adding "[Contributor]
* elects to include this software in this distribution under the [CDDL or GPL
* Version 2] license." If you don't indicate a single choice of license, a
* recipient has the option to distribute your version of this file under
* either the CDDL, the GPL Version 2 or to extend the choice of license to
* its licensees as provided above. However, if you add GPL Version 2 code
* and therefore, elected the GPL Version 2 license, then the option applies
* only if the new code is made subject to such option by the copyright
* holder.
*/
package org.glassfish.web.util;
/**
* This class encodes HTML display content for preventing XSS.
*/
public class HtmlEntityEncoder {
/**
* xssStrings:
* " => 34, % => 37, & => 38, ' => 39, ( => 40,
* ) => 41, + => 43, ; => 59, < => 60, > => 62
*/
private static String[] xssStrings = { //34-62
""", null,
null, "%", "&", "'", "(",
")", null, "+", null, null,
null, null, null, null, null,
null, null, null, null, null,
null, null, null, ";", "<",
null, ">"
};
private static final int START = 34;
private static final char DEFAULT_CHAR = ' ';
public static String encodeXSS(Object obj) {
if (obj == null) {
return null;
} else {
return encodeXSS(obj.toString());
}
}
/**
* Encode
* a) the following visible characters:
* " => 34, % => 37, & => 38, ' => 39, ( => 40,
* ) => 41, + => 43,
* ; => 59, < => 60,
* > => 62,
* b) ignore control characters
* c) ignore undefined characters
*/
public static String encodeXSS(String s) {
if (s == null) {
return null;
}
int len = s.length();
if (len == 0) {
return s;
}
StringBuilder sb = null;
for (int i = 0; i < len; i++) {
char c = s.charAt(i);
int ind =(int)c - START;
if (ind > -1 && ind < xssStrings.length && xssStrings[ind] != null) {
if (sb == null) {
sb = new StringBuilder(len);
sb.append(s.substring(0, i));
}
sb.append(xssStrings[ind]);
} else if (32 <= c && c <= 126 || 128 <= c && c <= 255 || c == 9
|| Character.isWhitespace(c)) {
if (sb != null) {
sb.append(c);
}
} else if (Character.isISOControl(c)) { // skip
if (sb == null) {
sb = new StringBuilder(len);
sb.append(s.substring(0, i));
}
sb.append(DEFAULT_CHAR);
} else if (Character.isHighSurrogate(c)) {
boolean valid = false;
if (i + 1 < len) {
char nextC = s.charAt(i + 1);
if (Character.isLowSurrogate(nextC)) {
valid = true;
if (sb != null) {
sb.append(c);
sb.append(nextC);
}
}
}
if (!valid) {
if (sb == null) {
sb = new StringBuilder(len);
sb.append(s.substring(0, i));
}
sb.append(DEFAULT_CHAR);
}
i++; // a pair
} else if (Character.isDefined(c)) {
if (sb != null) {
sb.append(c);
}
} else { // skip
if (sb == null) {
sb = new StringBuilder(len);
sb.append(s.substring(0, i));
}
sb.append(DEFAULT_CHAR);
}
}
if (sb != null) {
return sb.toString();
} else {
return s;
}
}
}