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1   /*
2    * Copyright 2014 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    *   https://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  package io.netty.handler.codec.http.websocketx;
17  
18  import io.netty.buffer.ByteBuf;
19  import io.netty.channel.ChannelFutureListener;
20  import io.netty.channel.ChannelHandlerContext;
21  import io.netty.channel.ChannelInboundHandlerAdapter;
22  
23  /**
24   *
25   */
26  public class Utf8FrameValidator extends ChannelInboundHandlerAdapter {
27  
28      private final boolean closeOnProtocolViolation;
29  
30      private int fragmentedFramesCount;
31      private Utf8Validator utf8Validator;
32  
33      public Utf8FrameValidator() {
34          this(true);
35      }
36  
37      public Utf8FrameValidator(boolean closeOnProtocolViolation) {
38          this.closeOnProtocolViolation = closeOnProtocolViolation;
39      }
40  
41      @Override
42      public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
43          if (msg instanceof WebSocketFrame) {
44              WebSocketFrame frame = (WebSocketFrame) msg;
45  
46              try {
47                  // Processing for possible fragmented messages for text and binary
48                  // frames
49                  if (((WebSocketFrame) msg).isFinalFragment()) {
50                      // Final frame of the sequence. Apparently ping frames are
51                      // allowed in the middle of a fragmented message
52                      if (!(frame instanceof PingWebSocketFrame)) {
53                          fragmentedFramesCount = 0;
54  
55                          // Check text for UTF8 correctness
56                          if ((frame instanceof TextWebSocketFrame) ||
57                                  (utf8Validator != null && utf8Validator.isChecking())) {
58                              // Check UTF-8 correctness for this payload
59                              checkUTF8String(frame.content());
60  
61                              // This does a second check to make sure UTF-8
62                              // correctness for entire text message
63                              utf8Validator.finish();
64                          }
65                      }
66                  } else {
67                      // Not final frame so we can expect more frames in the
68                      // fragmented sequence
69                      if (fragmentedFramesCount == 0) {
70                          // First text or binary frame for a fragmented set
71                          if (frame instanceof TextWebSocketFrame) {
72                              checkUTF8String(frame.content());
73                          }
74                      } else {
75                          // Subsequent frames - only check if init frame is text
76                          if (utf8Validator != null && utf8Validator.isChecking()) {
77                              checkUTF8String(frame.content());
78                          }
79                      }
80  
81                      // Increment counter
82                      fragmentedFramesCount++;
83                  }
84              } catch (CorruptedWebSocketFrameException e) {
85                  protocolViolation(ctx, frame, e);
86              }
87          }
88  
89          super.channelRead(ctx, msg);
90      }
91  
92      private void checkUTF8String(ByteBuf buffer) {
93          if (utf8Validator == null) {
94              utf8Validator = new Utf8Validator();
95          }
96          utf8Validator.check(buffer);
97      }
98  
99      private void protocolViolation(ChannelHandlerContext ctx, WebSocketFrame frame,
100                                    CorruptedWebSocketFrameException ex) {
101         frame.release();
102         if (closeOnProtocolViolation && ctx.channel().isOpen()) {
103             WebSocketCloseStatus closeStatus = ex.closeStatus();
104             String reasonText = ex.getMessage();
105             if (reasonText == null) {
106                 reasonText = closeStatus.reasonText();
107             }
108 
109             CloseWebSocketFrame closeFrame = new CloseWebSocketFrame(closeStatus.code(), reasonText);
110             ctx.writeAndFlush(closeFrame).addListener(ChannelFutureListener.CLOSE);
111         }
112 
113         throw ex;
114     }
115 
116     @Override
117     public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
118         super.exceptionCaught(ctx, cause);
119     }
120 }