1/* -*- c++ -*-
2 kmime_codec_base64.h
3
4 KMime, the KDE Internet mail/usenet news message library.
5 Copyright (c) 2001-2002 Marc Mutz <mutz@kde.org>
6
7 This library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Library General Public
9 License as published by the Free Software Foundation; either
10 version 2 of the License, or (at your option) any later version.
11
12 This library is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15 Library General Public License for more details.
16
17 You should have received a copy of the GNU Library General Public License
18 along with this library; see the file COPYING.LIB. If not, write to
19 the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA.
21*/
22/**
23 @file
24 This file is part of the API for handling @ref MIME data and
25 defines the @ref Base64 and @ref RFC2047B @ref Codec classes.
26
27 @brief
28 Defines the Base64Codec and Rfc2047BEncodingCodec classes.
29
30 @authors Marc Mutz \<mutz@kde.org\>
31
32 @glossary @anchor Base64 @anchor base64 @b base64:
33 a binary to text encoding scheme based on @ref RFC1421.
34
35 @glossary @anchor RFC1421 @anchor rfc1421 @b RFC @b 1421:
36 RFC that defines the <a href="http://tools.ietf.org/html/rfc1421">
37 Privacy Enhancement for Internet Electronic Mail: Part I:
38 Message Encryption and Authentication Procedures</a>.
39
40 @glossary @anchor RFC2045 @anchor rfc2045 @b RFC @b 2045:
41 RFC that defines the <a href="http://tools.ietf.org/html/rfc2045">
42 MIME Part One: Format of Internet Message Bodies</a>.
43
44 @glossary @anchor RFC2047 @anchor rfc2047 @b RFC @b 2047:
45 RFC that defines the <a href="http://tools.ietf.org/html/rfc2047">
46 MIME Part Three: Message Header Extensions for Non-ASCII Text</a>.
47
48 @glossary @anchor RFC2047B @anchor rfc2047b @b RFC @b 2047B:
49 Section 4.1 of @ref RFC2047.
50*/
51
52#ifndef __KMIME_CODEC_BASE64__
53#define __KMIME_CODEC_BASE64__
54
55#include "kmime_codecs.h"
56
57namespace KMime {
58
59/**
60 @brief
61 A class representing the @ref codec for @ref Base64 as specified in
62 @ref RFC2045
63*/
64class KMIME_EXPORT Base64Codec : public Codec
65{
66 protected:
67 friend class Codec;
68 /**
69 Constructs a Base64 codec.
70 */
71 Base64Codec() : Codec() {}
72
73 public:
74 /**
75 Destroys the codec.
76 */
77 virtual ~Base64Codec() {}
78
79 /**
80 @copydoc
81 Codec::name()
82 */
83 const char *name() const
84 { return "base64"; }
85
86 /**
87 @copydoc
88 Codec::maxEncodedSizeFor()
89 */
90 int maxEncodedSizeFor( int insize, bool withCRLF=false ) const
91 {
92 // first, the total number of 4-char packets will be:
93 int totalNumPackets = ( insize + 2 ) / 3;
94 // now, after every 76/4'th packet there needs to be a linebreak:
95 int numLineBreaks = totalNumPackets / ( 76 / 4 );
96 // and at the very end, too:
97 ++numLineBreaks;
98 // putting it all together, we have:
99 return 4 * totalNumPackets + ( withCRLF ? 2 : 1 ) * numLineBreaks;
100 }
101
102 /**
103 @copydoc
104 Codec::maxDecodedSizeFor()
105 */
106 int maxDecodedSizeFor( int insize, bool withCRLF=false ) const
107 {
108 // assuming all characters are part of the base64 stream (which
109 // does almost never hold due to required linebreaking; but
110 // additional non-base64 chars don't affect the output size), each
111 // 4-tupel of them becomes a 3-tupel in the decoded octet
112 // stream. So:
113 int result = ( ( insize + 3 ) / 4 ) * 3;
114 // but all of them may be \n, so
115 if ( withCRLF ) {
116 result *= 2; // :-o
117 }
118
119 return result;
120 }
121
122 /**
123 @copydoc
124 Codec::makeEncoder()
125 */
126 Encoder *makeEncoder( bool withCRLF=false ) const;
127
128 /**
129 @copydoc
130 Codec::makeDecoder()
131 */
132 Decoder *makeDecoder( bool withCRLF=false ) const;
133};
134
135/**
136 @brief
137 A class representing the @ref codec for the B encoding as specified
138 in @ref RFC2047B.
139*/
140class KMIME_EXPORT Rfc2047BEncodingCodec : public Base64Codec
141{
142 protected:
143 friend class Codec;
144 /**
145 Constructs a RFC2047B codec.
146 */
147 Rfc2047BEncodingCodec() : Base64Codec() {}
148
149 public:
150 /**
151 Destroys the codec.
152 */
153 virtual ~Rfc2047BEncodingCodec() {}
154
155 /**
156 @copydoc
157 Codec::name()
158 */
159 const char *name() const
160 { return "b"; }
161
162 /**
163 @copydoc
164 Codec::maxEncodedSizeFor()
165 */
166 int maxEncodedSizeFor( int insize, bool withCRLF=false ) const
167 {
168 Q_UNUSED( withCRLF );
169 // Each (begun) 3-octet triple becomes a 4 char quartet, so:
170 return ( ( insize + 2 ) / 3 ) * 4;
171 }
172
173 /**
174 @copydoc
175 Codec::maxDecodedSizeFor()
176 */
177 int maxDecodedSizeFor( int insize, bool withCRLF=false ) const
178 {
179 Q_UNUSED( withCRLF );
180 // Each 4-char quartet becomes a 3-octet triple, the last one
181 // possibly even less. So:
182 return ( ( insize + 3 ) / 4 ) * 3;
183 }
184
185 /**
186 @copydoc
187 Codec::makeEncoder()
188 */
189 Encoder *makeEncoder( bool withCRLF=false ) const;
190};
191
192} // namespace KMime
193
194#endif // __KMIME_CODEC_BASE64__
195