| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you 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 org.apache.myfaces.util; |
| |
| import java.io.FilterWriter; |
| import java.io.IOException; |
| import java.io.Writer; |
| |
| /** |
| * There are unicodes outside the ranges defined in the |
| * <a href="https://www.w3.org/TR/REC-xml/#charsets">XML 1.0 specification</a> that break XML parsers |
| * and therefore must be filtered out when writing partial responses. Otherwise this may lead to |
| * Denial of Service attacks. |
| * @see https://issues.apache.org/jira/browse/MYFACES-4266 |
| */ |
| public class IllegalXmlCharacterFilterWriter extends FilterWriter |
| { |
| private static final char BLANK_CHAR = ' '; |
| |
| public IllegalXmlCharacterFilterWriter(Writer out) |
| { |
| super(out); |
| } |
| |
| @Override |
| public void write(int c) throws IOException |
| { |
| if (isInvalidChar(c)) |
| { |
| super.write((int) BLANK_CHAR); |
| } |
| else |
| { |
| super.write(c); |
| } |
| } |
| |
| @Override |
| public void write(char[] cbuf, int off, int len) throws IOException |
| { |
| super.write(encodeCharArray(cbuf, off, len), off, len); |
| } |
| |
| @Override |
| public void write(String str, int off, int len) throws IOException |
| { |
| super.write(encodeString(str, off, len), off, len); |
| } |
| |
| private static String encodeString(String str, int off, int len) |
| { |
| if (str == null) |
| { |
| return null; |
| } |
| |
| int to = off + len; |
| boolean surrogateResolved = false; |
| char c; |
| int codePoint; |
| char cNext; |
| |
| char[] encoded = null; |
| for (int i = off; i < to; i++) |
| { |
| if (surrogateResolved == true) |
| { |
| surrogateResolved = false; |
| continue; |
| } |
| |
| c = str.charAt(i); |
| codePoint = c; |
| |
| if (Character.isHighSurrogate(c) && i + 1 < to) |
| { |
| cNext = str.charAt(i + 1); |
| if (Character.isLowSurrogate(cNext)) |
| { |
| codePoint = Character.toCodePoint(c, cNext); |
| surrogateResolved = true; |
| } |
| } |
| |
| // try to resolve surrogate, this is required e.g. for emojis |
| if ((!surrogateResolved && Character.isSurrogate(c)) || isInvalidChar(codePoint)) |
| { |
| if (encoded == null) |
| { |
| encoded = str.toCharArray(); |
| } |
| encoded[i] = BLANK_CHAR; |
| |
| if (surrogateResolved) |
| { |
| encoded[i + 1] = BLANK_CHAR; |
| } |
| } |
| } |
| |
| if (encoded != null) |
| { |
| return String.valueOf(encoded); |
| } |
| |
| return str; |
| } |
| |
| private static char[] encodeCharArray(char[] cbuf, int off, int len) |
| { |
| if (cbuf == null) |
| { |
| return null; |
| } |
| |
| int to = off + len; |
| |
| boolean surrogateResolved = false; |
| char c; |
| int codePoint; |
| char cNext; |
| |
| for (int i = off; i < to; i++) |
| { |
| if (surrogateResolved == true) |
| { |
| surrogateResolved = false; |
| continue; |
| } |
| |
| c = cbuf[i]; |
| codePoint = c; |
| |
| // try to resolve surrogate, this is required e.g. for emojis |
| if (Character.isHighSurrogate(c) && i + 1 < to) |
| { |
| cNext = cbuf[i + 1]; |
| if (Character.isLowSurrogate(cNext)) |
| { |
| codePoint = Character.toCodePoint(c, cNext); |
| surrogateResolved = true; |
| } |
| } |
| |
| if ((!surrogateResolved && Character.isSurrogate(c)) || isInvalidChar(codePoint)) |
| { |
| cbuf[i] = BLANK_CHAR; |
| |
| if (surrogateResolved) |
| { |
| cbuf[i + 1] = BLANK_CHAR; |
| } |
| } |
| } |
| return cbuf; |
| } |
| |
| private static boolean isInvalidChar(int codePoint) |
| { |
| if (codePoint == 1113088) |
| { |
| return true; |
| } |
| |
| if (codePoint == 0x9 || codePoint == 0xA || codePoint == 0xD) |
| { |
| return false; |
| } |
| if (codePoint >= 0x20 && codePoint <= 0xD7FF) |
| { |
| return false; |
| } |
| if (codePoint >= 0xE000 && codePoint <= 0xFFFD) |
| { |
| return false; |
| } |
| if (codePoint >= 0x10000 && codePoint <= 0x10FFFF) |
| { |
| return false; |
| } |
| |
| return true; |
| } |
| } |