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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.util;
21  
22  import java.io.FilterOutputStream;
23  import java.io.IOException;
24  import java.io.OutputStream;
25  
26  /***
27   * Adds extra dot if dot occurs in message body at beginning of line (according to RFC1939)
28   * Compare also org.apache.james.smtpserver.SMTPInputStream
29   */
30  public class ExtraDotOutputStream extends FilterOutputStream {
31  
32      /*
33      static public void main(String[] args) throws IOException
34      {
35          String data = ".This is a test\r\nof the thing.\r\nWe should not have much trouble.\r\n.doubled?\r\nor not?\n.doubled\nor not?\r\n\r\n\n\n\r\r\r\n";
36  
37          OutputStream os = new ExtraDotOutputStream(System.out);
38          os.write(data.getBytes());
39      }
40      */
41  
42      /***
43       * Counter for number of last (0A or 0D).
44       */
45      protected int countLast0A0D;
46  
47      /***
48       * Constructor that wraps an OutputStream.
49       *
50       * @param out the OutputStream to be wrapped
51       */
52      public ExtraDotOutputStream(OutputStream out) {
53          super(out);
54          countLast0A0D = 2; // we already assume a CRLF at beginning (otherwise TOP would not work correctly !)
55      }
56  
57      /***
58       * Writes a byte to the stream, adding dots where appropriate.
59       * Also fixes any naked CR or LF to the RFC 2821 mandated CFLF
60       * pairing.
61       *
62       * @param b the byte to write
63       *
64       * @throws IOException if an error occurs writing the byte
65       */
66      public void write(int b) throws IOException {
67          switch (b) {
68              case '.':
69                  if (countLast0A0D == 2) {
70                      // add extra dot (the first of the pair)
71                      out.write('.');
72                  }
73                  countLast0A0D = 0;
74                  break;
75              case '\r':
76                  if (countLast0A0D == 1) out.write('\n'); // two CR in a row, so insert an LF first
77                  countLast0A0D = 1;
78                  break;
79              case '\n':
80                  /* RFC 2821 #2.3.7 mandates that line termination is
81                   * CRLF, and that CR and LF must not be transmitted
82                   * except in that pairing.  If we get a naked LF,
83                   * convert to CRLF.
84                   */
85                  if (countLast0A0D != 1) out.write('\r');
86                  countLast0A0D = 2;
87                  break;
88              default:
89                  // we're  no longer at the start of a line
90                  countLast0A0D = 0;
91                  break;
92          }
93          out.write(b);
94      }
95      
96      /***
97       * Ensure that the stream is CRLF terminated.
98       * 
99       * @throws IOException  if an error occurs writing the byte
100      */
101     public void checkCRLFTerminator() throws IOException {
102         if (countLast0A0D != 2) {
103             write('\n');
104         }
105     }
106 }