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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  package io.netty.example.socksproxy;
17  
18  import io.netty.channel.ChannelHandler;
19  import io.netty.channel.ChannelHandlerContext;
20  import io.netty.channel.SimpleChannelInboundHandler;
21  import io.netty.handler.codec.socksx.SocksMessage;
22  import io.netty.handler.codec.socksx.v4.Socks4CommandRequest;
23  import io.netty.handler.codec.socksx.v4.Socks4CommandType;
24  import io.netty.handler.codec.socksx.v5.DefaultSocks5InitialResponse;
25  import io.netty.handler.codec.socksx.v5.DefaultSocks5PasswordAuthResponse;
26  import io.netty.handler.codec.socksx.v5.Socks5AuthMethod;
27  import io.netty.handler.codec.socksx.v5.Socks5InitialRequest;
28  import io.netty.handler.codec.socksx.v5.Socks5CommandRequest;
29  import io.netty.handler.codec.socksx.v5.Socks5CommandRequestDecoder;
30  import io.netty.handler.codec.socksx.v5.Socks5CommandType;
31  import io.netty.handler.codec.socksx.v5.Socks5PasswordAuthRequest;
32  import io.netty.handler.codec.socksx.v5.Socks5PasswordAuthStatus;
33  
34  @ChannelHandler.Sharable
35  public final class SocksServerHandler extends SimpleChannelInboundHandler<SocksMessage> {
36  
37      public static final SocksServerHandler INSTANCE = new SocksServerHandler();
38  
39      private SocksServerHandler() { }
40  
41      @Override
42      public void channelRead0(ChannelHandlerContext ctx, SocksMessage socksRequest) throws Exception {
43          switch (socksRequest.version()) {
44              case SOCKS4a:
45                  Socks4CommandRequest socksV4CmdRequest = (Socks4CommandRequest) socksRequest;
46                  if (socksV4CmdRequest.type() == Socks4CommandType.CONNECT) {
47                      ctx.pipeline().addLast(new SocksServerConnectHandler());
48                      ctx.pipeline().remove(this);
49                      ctx.fireChannelRead(socksRequest);
50                  } else {
51                      ctx.close();
52                  }
53                  break;
54              case SOCKS5:
55                  if (socksRequest instanceof Socks5InitialRequest) {
56                      // auth support example
57                      //ctx.pipeline().addFirst(new Socks5PasswordAuthRequestDecoder());
58                      //ctx.write(new DefaultSocks5AuthMethodResponse(Socks5AuthMethod.PASSWORD));
59                      ctx.pipeline().addFirst(new Socks5CommandRequestDecoder());
60                      ctx.write(new DefaultSocks5InitialResponse(Socks5AuthMethod.NO_AUTH));
61                  } else if (socksRequest instanceof Socks5PasswordAuthRequest) {
62                      ctx.pipeline().addFirst(new Socks5CommandRequestDecoder());
63                      ctx.write(new DefaultSocks5PasswordAuthResponse(Socks5PasswordAuthStatus.SUCCESS));
64                  } else if (socksRequest instanceof Socks5CommandRequest) {
65                      Socks5CommandRequest socks5CmdRequest = (Socks5CommandRequest) socksRequest;
66                      if (socks5CmdRequest.type() == Socks5CommandType.CONNECT) {
67                          ctx.pipeline().addLast(new SocksServerConnectHandler());
68                          ctx.pipeline().remove(this);
69                          ctx.fireChannelRead(socksRequest);
70                      } else {
71                          ctx.close();
72                      }
73                  } else {
74                      ctx.close();
75                  }
76                  break;
77              case UNKNOWN:
78                  ctx.close();
79                  break;
80          }
81      }
82  
83      @Override
84      public void channelReadComplete(ChannelHandlerContext ctx) {
85          ctx.flush();
86      }
87  
88      @Override
89      public void exceptionCaught(ChannelHandlerContext ctx, Throwable throwable) {
90          throwable.printStackTrace();
91          SocksServerUtils.closeOnFlush(ctx.channel());
92      }
93  }