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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.jdkim.canon;
21  
22  import java.io.FilterOutputStream;
23  import java.io.IOException;
24  import java.io.OutputStream;
25  
26  /**
27   * Implements Relaxed canonicalization for the body as defined in RFC4871 -
28   * 3.4.4. The "relaxed" Body Canonicalization Algorithm
29   */
30  public class RelaxedBodyCanonicalizer extends FilterOutputStream {
31  
32      private boolean pendingSpaces;
33  
34      public RelaxedBodyCanonicalizer(OutputStream out) {
35          super(new SimpleBodyCanonicalizer(out));
36          pendingSpaces = false;
37      }
38  
39      public void write(byte[] buffer, int off, int len) throws IOException {
40          int start = off;
41          int end = len + off;
42          for (int k = off; k < end; k++) {
43              if (pendingSpaces) {
44                  if (buffer[k] != ' ' && buffer[k] != '\t') {
45                      if (buffer[k] != '\r')
46                          out.write(' ');
47                      pendingSpaces = false;
48                      len = len - k + start;
49                      start = k;
50                  }
51              } else {
52                  if (buffer[k] == ' ' || buffer[k] == '\t') {
53                      if (k + 1 < end && buffer[k] == ' ' && buffer[k + 1] != ' '
54                              && buffer[k + 1] != '\t' && buffer[k + 1] != '\r') {
55                          // optimization: we skip single spaces
56                          // make sure we optimize only when we are on a space.
57                      } else {
58                          // compute everything from start to end;
59                          out.write(buffer, start, k - start);
60                          pendingSpaces = true;
61                      }
62                  }
63              }
64          }
65          if (!pendingSpaces) {
66              out.write(buffer, start, len);
67          }
68      }
69  
70      public void write(int b) throws IOException {
71          if (pendingSpaces) {
72              if (b != ' ' && b != '\t') {
73                  if (b != '\r')
74                      out.write(' ');
75                  pendingSpaces = false;
76                  out.write(b);
77              }
78          } else {
79              if (b == ' ' || b == '\t') {
80                  pendingSpaces = true;
81              } else {
82                  out.write(b);
83              }
84          }
85      }
86  
87      public void close() throws IOException {
88          complete();
89          super.close();
90      }
91  
92      /**
93       * Called internally to make sure we output the buffered whitespace if any.
94       */
95      private void complete() throws IOException {
96          if (pendingSpaces)
97              out.write(' ');
98      }
99  
100 }