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1   /*****************************************************************
2    * Licensed to the Apache Software Foundation (ASF) under one   *
3    * or more contributor license agreements.  See the NOTICE file *
4    * distributed with this work for additional information        *
5    * regarding copyright ownership.  The ASF licenses this file   *
6    * to you under the Apache License, Version 2.0 (the            *
7    * "License"); you may not use this file except in compliance   *
8    * with the License.  You may obtain a copy of the License at   *
9    *                                                              *
10   *   http://www.apache.org/licenses/LICENSE-2.0                 *
11   *                                                              *
12   * Unless required by applicable law or agreed to in writing,   *
13   * software distributed under the License is distributed on an  *
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY       *
15   * KIND, either express or implied.  See the License for the    *
16   * specific language governing permissions and limitations      *
17   * under the License.                                           *
18   ****************************************************************/
19  
20  package org.apache.james.smtpserver;
21  
22  import org.apache.james.util.mail.dsn.DSNStatus;
23  
24  /***
25    * Default command handler for handling unknown commands
26    */
27  public class UnknownCmdHandler implements CommandHandler {
28  
29      /***
30       * The name of the command handled by the command handler
31       */
32      public static final String UNKNOWN_COMMAND = "UNKNOWN";
33  
34      /***
35       * Handler method called upon receipt of an unrecognized command.
36       * Returns an error response and logs the command.
37       *
38       * @see org.apache.james.smtpserver.CommandHandler#onCommand(SMTPSession)
39      **/
40      public void onCommand(SMTPSession session) {
41  
42          //If there was message failure, don't consider it as an unknown command
43          if (session.getState().get(SMTPSession.MESG_FAILED) != null) {
44              return;
45          }
46  
47          session.getResponseBuffer().append("500 "+DSNStatus.getStatus(DSNStatus.PERMANENT, DSNStatus.DELIVERY_INVALID_CMD))
48                        .append(" Command ")
49                        .append(session.getCommandName())
50                        .append(" unrecognized.");
51          String responseString = session.clearResponseBuffer();
52  
53          session.writeResponse(responseString);
54      }
55  
56  }