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1   /*
2    * Copyright 2012 The Netty Project
3    *
4    * The Netty Project licenses this file to you under the Apache License,
5    * version 2.0 (the "License"); you may not use this file except in compliance
6    * with the License. You may obtain a copy of the License at:
7    *
8    *   http://www.apache.org/licenses/LICENSE-2.0
9    *
10   * Unless required by applicable law or agreed to in writing, software
11   * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
12   * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
13   * License for the specific language governing permissions and limitations
14   * under the License.
15   */
16  /*
17   * Adaptation of http://bjoern.hoehrmann.de/utf-8/decoder/dfa/
18   *
19   * Copyright (c) 2008-2009 Bjoern Hoehrmann <[email protected]>
20   *
21   * Permission is hereby granted, free of charge, to any person obtaining a copy of this software
22   * and associated documentation files (the "Software"), to deal in the Software without restriction,
23   * including without limitation the rights to use, copy, modify, merge, publish, distribute,
24   * sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is
25   * furnished to do so, subject to the following conditions:
26   *
27   * The above copyright notice and this permission notice shall be included in all copies or
28   * substantial portions of the Software.
29   *
30   * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING
31   * BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
32   * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
33   * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
34   * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
35   */
36  package io.netty.handler.codec.http.websocketx;
37  
38  import io.netty.buffer.ByteBuf;
39  import io.netty.handler.codec.CorruptedFrameException;
40  import io.netty.util.ByteProcessor;
41  
42  /**
43   * Checks UTF8 bytes for validity
44   */
45  final class Utf8Validator implements ByteProcessor {
46      private static final int UTF8_ACCEPT = 0;
47      private static final int UTF8_REJECT = 12;
48  
49      private static final byte[] TYPES = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
50              0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
51              0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
52              0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
53              0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1,
54              1, 1, 1, 1, 1, 1, 1, 1, 1, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 7, 7, 7, 7,
55              7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 8,
56              8, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
57              2, 2, 10, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 3, 3, 11, 6, 6, 6, 5, 8, 8, 8, 8, 8,
58              8, 8, 8, 8, 8, 8 };
59  
60      private static final byte[] STATES = { 0, 12, 24, 36, 60, 96, 84, 12, 12, 12, 48, 72, 12, 12,
61              12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 12, 0, 12, 12, 12, 12, 12, 0, 12, 0, 12, 12,
62              12, 24, 12, 12, 12, 12, 12, 24, 12, 24, 12, 12, 12, 12, 12, 12, 12, 12, 12, 24, 12, 12,
63              12, 12, 12, 24, 12, 12, 12, 12, 12, 12, 12, 24, 12, 12, 12, 12, 12, 12, 12, 12, 12, 36,
64              12, 36, 12, 12, 12, 36, 12, 12, 12, 12, 12, 36, 12, 36, 12, 12, 12, 36, 12, 12, 12, 12,
65              12, 12, 12, 12, 12, 12 };
66  
67      @SuppressWarnings("RedundantFieldInitialization")
68      private int state = UTF8_ACCEPT;
69      private int codep;
70      private boolean checking;
71  
72      public void check(ByteBuf buffer) {
73          checking = true;
74          buffer.forEachByte(this);
75      }
76  
77      public void finish() {
78          checking = false;
79          codep = 0;
80          if (state != UTF8_ACCEPT) {
81              state = UTF8_ACCEPT;
82              throw new CorruptedFrameException("bytes are not UTF-8");
83          }
84      }
85  
86      @Override
87      public boolean process(byte b) throws Exception {
88          byte type = TYPES[b & 0xFF];
89  
90          codep = state != UTF8_ACCEPT ? b & 0x3f | codep << 6 : 0xff >> type & b;
91  
92          state = STATES[state + type];
93  
94          if (state == UTF8_REJECT) {
95              checking = false;
96              throw new CorruptedFrameException("bytes are not UTF-8");
97          }
98          return true;
99      }
100 
101     public boolean isChecking() {
102         return checking;
103     }
104 }