1/* -*- c++ -*-
2 SPDX-FileCopyrightText: 2001 Marc Mutz <mutz@kde.org>
3
4 SPDX-License-Identifier: LGPL-2.0-or-later
5*/
6
7#include "kcodecsbase64.h"
8#include "kcodecs_p.h"
9
10#include <QDebug>
11
12#include <cassert>
13
14using namespace KCodecs;
15
16namespace KCodecs
17{
18// codec for base64 as specified in RFC 2045
19// class Base64Codec;
20// class Base64Decoder;
21// class Base64Encoder;
22
23// codec for the B encoding as specified in RFC 2047
24// class Rfc2047BEncodingCodec;
25// class Rfc2047BEncodingEncoder;
26// class Rfc2047BEncodingDecoder;
27
28//@cond PRIVATE
29static const uchar base64DecodeMap[128] = {
30 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64,
31
32 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 64, 62, 64, 64, 64, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 64, 64, 64, 64, 64, 64,
33
34 64, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 64, 64, 64, 64, 64,
35
36 64, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 64, 64, 64, 64, 64};
37
38static const char base64EncodeMap[64] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V',
39 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r',
40 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/'};
41//@endcond
42
43class Base64Decoder : public Decoder
44{
45 uint mStepNo;
46 uchar mOutbits;
47 bool mSawPadding : 1;
48
49protected:
50 friend class Base64Codec;
51 Base64Decoder(Codec::NewlineType newline = Codec::NewlineLF)
52 : Decoder(newline)
53 , mStepNo(0)
54 , mOutbits(0)
55 , mSawPadding(false)
56 {
57 }
58
59public:
60 ~Base64Decoder() override
61 {
62 }
63
64 bool decode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend) override;
65 // ### really needs no finishing???
66 bool finish(char *&dcursor, const char *const dend) override
67 {
68 Q_UNUSED(dcursor);
69 Q_UNUSED(dend);
70 return true;
71 }
72};
73
74class Base64Encoder : public Encoder
75{
76 uint mStepNo;
77 /** number of already written base64-quartets on current line */
78 uint mWrittenPacketsOnThisLine;
79 uchar mNextbits;
80 bool mInsideFinishing : 1;
81
82protected:
83 friend class Rfc2047BEncodingCodec;
84 friend class Rfc2047BEncodingEncoder;
85 friend class Base64Codec;
86 Base64Encoder(Codec::NewlineType newline = Codec::NewlineLF)
87 : Encoder(newline)
88 , mStepNo(0)
89 , mWrittenPacketsOnThisLine(0)
90 , mNextbits(0)
91 , mInsideFinishing(false)
92 {
93 }
94
95 bool generic_finish(char *&dcursor, const char *const dend, bool withLFatEnd);
96
97public:
98 ~Base64Encoder() override
99 {
100 }
101
102 bool encode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend) override;
103
104 bool finish(char *&dcursor, const char *const dend) override;
105
106protected:
107 bool writeBase64(uchar ch, char *&dcursor, const char *const dend)
108 {
109 return write(ch: base64EncodeMap[ch], dcursor, dend);
110 }
111};
112
113class Rfc2047BEncodingEncoder : public Base64Encoder
114{
115protected:
116 friend class Rfc2047BEncodingCodec;
117 Rfc2047BEncodingEncoder(Codec::NewlineType newline = Codec::NewlineLF)
118 : Base64Encoder(newline)
119 {
120 }
121
122public:
123 bool encode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend) override;
124 bool finish(char *&dcursor, const char *const dend) override;
125};
126
127Encoder *Base64Codec::makeEncoder(Codec::NewlineType newline) const
128{
129 return new Base64Encoder(newline);
130}
131
132Decoder *Base64Codec::makeDecoder(Codec::NewlineType newline) const
133{
134 return new Base64Decoder(newline);
135}
136
137Encoder *Rfc2047BEncodingCodec::makeEncoder(Codec::NewlineType newline) const
138{
139 return new Rfc2047BEncodingEncoder(newline);
140}
141
142/********************************************************/
143/********************************************************/
144/********************************************************/
145
146bool Base64Decoder::decode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend)
147{
148 while (dcursor != dend && scursor != send) {
149 uchar ch = *scursor++;
150 uchar value;
151
152 // try converting ch to a 6-bit value:
153 if (ch < 128) {
154 value = base64DecodeMap[ch];
155 } else {
156 value = 64;
157 }
158
159 // ch isn't of the base64 alphabet, check for other significant chars:
160 if (value >= 64) {
161 if (ch == '=') {
162 // padding:
163 if (mStepNo == 0 || mStepNo == 1) {
164 if (!mSawPadding) {
165 // malformed
166 // qWarning() << "Base64Decoder: unexpected padding"
167 // "character in input stream";
168 }
169 mSawPadding = true;
170 break;
171 } else if (mStepNo == 2) {
172 // ok, there should be another one
173 } else if (mStepNo == 3) {
174 // ok, end of encoded stream
175 mSawPadding = true;
176 break;
177 }
178 mSawPadding = true;
179 mStepNo = (mStepNo + 1) % 4;
180 continue;
181 } else {
182 // non-base64 alphabet
183 continue;
184 }
185 }
186
187 if (mSawPadding) {
188 // qWarning() << "Base64Decoder: Embedded padding character"
189 // "encountered!";
190 return true;
191 }
192
193 // add the new bits to the output stream and flush full octets:
194 switch (mStepNo) {
195 case 0:
196 mOutbits = value << 2;
197 break;
198 case 1:
199 *dcursor++ = (char)(mOutbits | value >> 4);
200 mOutbits = value << 4;
201 break;
202 case 2:
203 *dcursor++ = (char)(mOutbits | value >> 2);
204 mOutbits = value << 6;
205 break;
206 case 3:
207 *dcursor++ = (char)(mOutbits | value);
208 mOutbits = 0;
209 break;
210 default:
211 assert(0);
212 }
213 mStepNo = (mStepNo + 1) % 4;
214 }
215
216 // return false when caller should call us again:
217 return scursor == send;
218} // Base64Decoder::decode()
219
220bool Base64Encoder::encode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend)
221{
222 const uint maxPacketsPerLine = 76 / 4;
223
224 // detect when the caller doesn't adhere to our rules:
225 if (mInsideFinishing) {
226 return true;
227 }
228
229 while (scursor != send && dcursor != dend) {
230 // properly empty the output buffer before starting something new:
231 // ### fixme: we can optimize this away, since the buffer isn't
232 // written to anyway (most of the time)
233 if (d->outputBufferCursor && !flushOutputBuffer(dcursor, dend)) {
234 return scursor == send;
235 }
236
237 uchar ch = *scursor++;
238 // mNextbits // (part of) value of next sextet
239
240 // check for line length;
241 if (mStepNo == 0 && mWrittenPacketsOnThisLine >= maxPacketsPerLine) {
242 writeCRLF(dcursor, dend);
243 mWrittenPacketsOnThisLine = 0;
244 }
245
246 // depending on mStepNo, extract value and mNextbits from the
247 // octet stream:
248 switch (mStepNo) {
249 case 0:
250 assert(mNextbits == 0);
251 writeBase64(ch: ch >> 2, dcursor, dend); // top-most 6 bits -> output
252 mNextbits = (ch & 0x3) << 4; // 0..1 bits -> 4..5 in mNextbits
253 break;
254 case 1:
255 assert((mNextbits & ~0x30) == 0);
256 writeBase64(ch: mNextbits | ch >> 4, dcursor, dend); // 4..7 bits -> 0..3 in value
257 mNextbits = (ch & 0xf) << 2; // 0..3 bits -> 2..5 in mNextbits
258 break;
259 case 2:
260 assert((mNextbits & ~0x3C) == 0);
261 writeBase64(ch: mNextbits | ch >> 6, dcursor, dend); // 6..7 bits -> 0..1 in value
262 writeBase64(ch: ch & 0x3F, dcursor, dend); // 0..5 bits -> output
263 mNextbits = 0;
264 mWrittenPacketsOnThisLine++;
265 break;
266 default:
267 assert(0);
268 }
269 mStepNo = (mStepNo + 1) % 3;
270 }
271
272 if (d->outputBufferCursor) {
273 flushOutputBuffer(dcursor, dend);
274 }
275
276 return scursor == send;
277}
278
279bool Rfc2047BEncodingEncoder::encode(const char *&scursor, const char *const send, char *&dcursor, const char *const dend)
280{
281 // detect when the caller doesn't adhere to our rules:
282 if (mInsideFinishing) {
283 return true;
284 }
285
286 while (scursor != send && dcursor != dend) {
287 // properly empty the output buffer before starting something new:
288 // ### fixme: we can optimize this away, since the buffer isn't
289 // written to anyway (most of the time)
290 if (d->outputBufferCursor && !flushOutputBuffer(dcursor, dend)) {
291 return scursor == send;
292 }
293
294 uchar ch = *scursor++;
295 // mNextbits // (part of) value of next sextet
296
297 // depending on mStepNo, extract value and mNextbits from the
298 // octet stream:
299 switch (mStepNo) {
300 case 0:
301 assert(mNextbits == 0);
302 writeBase64(ch: ch >> 2, dcursor, dend); // top-most 6 bits -> output
303 mNextbits = (ch & 0x3) << 4; // 0..1 bits -> 4..5 in mNextbits
304 break;
305 case 1:
306 assert((mNextbits & ~0x30) == 0);
307 writeBase64(ch: mNextbits | ch >> 4, dcursor, dend); // 4..7 bits -> 0..3 in value
308 mNextbits = (ch & 0xf) << 2; // 0..3 bits -> 2..5 in mNextbits
309 break;
310 case 2:
311 assert((mNextbits & ~0x3C) == 0);
312 writeBase64(ch: mNextbits | ch >> 6, dcursor, dend); // 6..7 bits -> 0..1 in value
313 writeBase64(ch: ch & 0x3F, dcursor, dend); // 0..5 bits -> output
314 mNextbits = 0;
315 break;
316 default:
317 assert(0);
318 }
319 mStepNo = (mStepNo + 1) % 3;
320 }
321
322 if (d->outputBufferCursor) {
323 flushOutputBuffer(dcursor, dend);
324 }
325
326 return scursor == send;
327}
328
329bool Base64Encoder::finish(char *&dcursor, const char *const dend)
330{
331 return generic_finish(dcursor, dend, withLFatEnd: true);
332}
333
334bool Rfc2047BEncodingEncoder::finish(char *&dcursor, const char *const dend)
335{
336 return generic_finish(dcursor, dend, withLFatEnd: false);
337}
338
339bool Base64Encoder::generic_finish(char *&dcursor, const char *const dend, bool withLFatEnd)
340{
341 if (mInsideFinishing) {
342 return flushOutputBuffer(dcursor, dend);
343 }
344
345 if (d->outputBufferCursor && !flushOutputBuffer(dcursor, dend)) {
346 return false;
347 }
348
349 mInsideFinishing = true;
350
351 //
352 // writing out the last mNextbits...
353 //
354 switch (mStepNo) {
355 case 1: // 2 mNextbits waiting to be written. Needs two padding chars:
356 case 2: // 4 or 6 mNextbits waiting to be written. Completes a block
357 writeBase64(ch: mNextbits, dcursor, dend);
358 mNextbits = 0;
359 break;
360 case 0: // no padding, nothing to be written, except possibly the CRLF
361 assert(mNextbits == 0);
362 break;
363 default:
364 assert(0);
365 }
366
367 //
368 // adding padding...
369 //
370 switch (mStepNo) {
371 case 1:
372 write(ch: '=', dcursor, dend);
373 Q_FALLTHROUGH();
374 // fall through:
375 case 2:
376 write(ch: '=', dcursor, dend);
377 Q_FALLTHROUGH();
378 // fall through:
379 case 0: // completed a quartet - add CRLF
380 if (withLFatEnd) {
381 writeCRLF(dcursor, dend);
382 }
383 return flushOutputBuffer(dcursor, dend);
384 default:
385 assert(0);
386 }
387 return true; // asserts get compiled out
388}
389
390} // namespace KCodecs
391

source code of kcodecs/src/kcodecsbase64.cpp