mcs/class/System.Web/System.Web.Mail/Base64AttachmentEncoder.cs

   1 //
   2 // System.Web.Mail.Base64AttachmentEncoder.cs
   3 //
   4 // Author(s):
   5 //   Per Arneng <pt99par@student.bth.se>
   6 //
   7 //
   8
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29 using System;
  30 using System.IO;
  31 using System.Text;
  32 using System.Security.Cryptography;
  33
  34 namespace System.Web.Mail {
  35
  36     // a class that handles Base64 encoding for attachments
  37     internal class Base64AttachmentEncoder : IAttachmentEncoder {
  38
  39         // reads bytes from a stream and writes the encoded
  40         // as base64 encoded characters. ( 60 chars on each row)
  41         public void EncodeStream(  Stream ins , Stream outs ) {
  42
  43             if( ( ins == null ) || ( outs == null ) )
  44                 throw new ArgumentNullException( "The input and output streams may not " +
  45                                                  "be null.");
  46
  47             ICryptoTransform base64 = new ToBase64Transform();
  48
  49             // the buffers
  50             byte[] plainText = new byte[ base64.InputBlockSize ];
  51             byte[] cipherText = new byte[ base64.OutputBlockSize ];
  52
  53             int readLength = 0;
  54             int trLength = 0;
  55             int count = 0;
  56             byte[] newln = new byte[] { 13 , 10 }; //CR LF with mail
  57
  58             // read through the stream until there
  59             // are no more bytes left
  60             while( true ) {
  61
  62                 // read some bytes
  63                 readLength = ins.Read( plainText , 0 , plainText.Length );
  64
  65                 // break when there is no more data
  66                 if( readLength < 1 ) break;
  67
  68                 // transfrom and write the blocks. If the block size
  69                 // is less than the InputBlockSize then write the final block
  70                 if( readLength == plainText.Length ) {
  71
  72                     trLength = base64.TransformBlock( plainText , 0 ,
  73                                                       plainText.Length ,
  74                                                       cipherText , 0 );
  75
  76                     // write the data
  77                     outs.Write( cipherText , 0 , cipherText.Length );
  78
  79
  80                     // do this to output lines that
  81                     // are 60 chars long
  82                     count += cipherText.Length;
  83                     if( count == 60 ) {
  84                         outs.Write( newln , 0 , newln.Length );
  85                         count = 0;
  86                     }
  87
  88                 } else {
  89
  90                     // convert the final blocks of bytes and write them
  91                     cipherText = base64.TransformFinalBlock( plainText , 0 , readLength );
  92                     outs.Write( cipherText , 0 , cipherText.Length );
  93
  94                 }
  95
  96             }
  97
  98             outs.Write( newln , 0 , newln.Length );
  99         }
 100
 101
 102     }
 103
 104
 105
 106 }