"Fossies" - the Fresh Open Source Software Archive 
Member "tin-2.4.2/src/rfc2045.c" (8 Dec 2017, 15193 Bytes) of package /linux/misc/tin-2.4.2.tar.xz:
As a special service "Fossies" has tried to format the requested source page into HTML format using (guessed) C and C++ source code syntax highlighting (style:
standard) with prefixed line numbers and
code folding option.
Alternatively you can here
view or
download the uninterpreted source code file.
For more information about "rfc2045.c" see the
Fossies "Dox" file reference documentation and the latest
Fossies "Diffs" side-by-side code changes report:
2.4.1_vs_2.4.2.
1 /*
2 * Project : tin - a Usenet reader
3 * Module : rfc2045.c
4 * Author : Chris Blum <chris@resolution.de>
5 * Created : 1995-09-01
6 * Updated : 2017-02-17
7 * Notes : RFC 2045/2047 encoding
8 *
9 * Copyright (c) 1995-2018 Chris Blum <chris@resolution.de>
10 * All rights reserved.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. The name of the author may not be used to endorse or promote
21 * products derived from this software without specific prior written
22 * permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS
25 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
26 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
28 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
30 * GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
31 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
32 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
33 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
34 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
35 */
36
37
38 #ifndef TIN_H
39 # include "tin.h"
40 #endif /* !TIN_H */
41
42 /*
43 * local prototypes
44 */
45 static int put_rest(char **rest, char **line, size_t *max_line_len, const int offset);
46 static unsigned char bin2hex(unsigned int x);
47 static void set_rest(char **rest, const char *ptr);
48
49
50 static unsigned char
51 bin2hex(
52 unsigned int x)
53 {
54 if (x < 10)
55 return x + '0';
56 return x - 10 + 'A';
57 }
58
59
60 #define HI4BITS(c) ((unsigned char) (*EIGHT_BIT(c) >> 4))
61 #define LO4BITS(c) ((unsigned char) (*c & 0xf))
62
63 /*
64 * A MIME replacement for fputs. e can be 'b' for base64, 'q' for
65 * quoted-printable, or 8 (default) for 8bit. Long lines get broken in
66 * encoding modes. If line is the null pointer, flush internal buffers.
67 * NOTE: Use only with text encodings, because line feed characters (0x0A)
68 * will be encoded as CRLF line endings when using base64! This will
69 * certainly break any binary format ...
70 */
71 void
72 rfc1521_encode(
73 char *line,
74 FILE *f,
75 int e)
76 {
77 int i;
78 static char *b = NULL; /* they must be static for base64 */
79 static char buffer[80];
80 static int bits = 0;
81 static int xpos = 0;
82 static unsigned long pattern = 0;
83
84 if (e == 'b') {
85 if (!b) {
86 b = buffer;
87 *buffer = '\0';
88 }
89 if (!line) { /* flush */
90 if (bits) {
91 if (xpos >= 73) {
92 *b++ = '\n';
93 *b = '\0';
94 fputs(buffer, f);
95 b = buffer;
96 xpos = 0;
97 }
98 pattern <<= 24 - bits;
99 for (i = 0; i < 4; i++) {
100 if (bits >= 0) {
101 *b++ = base64_alphabet[(pattern & 0xfc0000) >> 18];
102 pattern <<= 6;
103 bits -= 6;
104 } else
105 *b++ = '=';
106 xpos++;
107 }
108 pattern = 0;
109 bits = 0;
110 }
111 if (xpos) {
112 *b = '\0';
113 fputs(buffer, f);
114 xpos = 0;
115 }
116 b = NULL;
117 } else {
118 char *line_crlf = line;
119 size_t len = strlen(line);
120 char tmpbuf[2050]; /* FIXME: this is sizeof(buffer)+2 from rfc15211522_encode() */
121
122 /*
123 * base64 requires CRLF line endings in text types
124 * convert LF to CRLF if not CRLF already (Windows?)
125 */
126 if ((len > 0) && (line[len - 1] == '\n') &&
127 ((len == 1) || (line[len - 2] != '\r'))) {
128 STRCPY(tmpbuf, line);
129 line_crlf = tmpbuf;
130 line_crlf[len - 1] = '\r';
131 line_crlf[len] = '\n';
132 line_crlf[len + 1] = '\0';
133 }
134
135 while (*line_crlf) {
136 pattern <<= 8;
137 pattern |= *EIGHT_BIT(line_crlf)++;
138 bits += 8;
139 if (bits >= 24) {
140 if (xpos >= 73) {
141 *b++ = '\n';
142 *b = '\0';
143 b = buffer;
144 xpos = 0;
145 fputs(buffer, f);
146 }
147 for (i = 0; i < 4; i++) {
148 *b++ = base64_alphabet[(pattern >> (bits - 6)) & 0x3f];
149 xpos++;
150 bits -= 6;
151 }
152 pattern = 0;
153 }
154 }
155 }
156 } else if (e == 'q') {
157 if (!line) {
158 /*
159 * we don't really flush anything in qp mode, just set
160 * xpos to 0 in case the last line wasn't terminated by
161 * \n.
162 */
163 xpos = 0;
164 b = NULL;
165 return;
166 }
167 b = buffer;
168 while (*line) {
169 if (isspace((unsigned char) *line) && *line != '\n') {
170 char *l = line + 1;
171
172 while (*l) {
173 if (!isspace((unsigned char) *l)) { /* it's not trailing whitespace, no encoding needed */
174 *b++ = *line++;
175 xpos++;
176 break;
177 }
178 l++;
179 }
180 if (!*l) { /* trailing whitespace must be encoded */
181 *b++ = '=';
182 *b++ = bin2hex(HI4BITS(line));
183 *b++ = bin2hex(LO4BITS(line));
184 xpos += 3;
185 line++;
186 }
187 } else if ((!is_EIGHT_BIT(line) && *line != '=')
188 || (*line == '\n')) {
189 *b++ = *line++;
190 xpos++;
191 if (*(line - 1) == '\n')
192 break;
193 } else {
194 *b++ = '=';
195 *b++ = bin2hex(HI4BITS(line));
196 *b++ = bin2hex(LO4BITS(line));
197 xpos += 3;
198 line++;
199 }
200 if (xpos > 72 && *line != '\n') { /* 72 +3 [worst case] + equal sign = 76 :-) */
201 *b++ = '='; /* break long lines with a 'soft line break' */
202 *b++ = '\n';
203 *b++ = '\0';
204 fputs(buffer, f);
205 b = buffer;
206 xpos = 0;
207 }
208 }
209 *b = '\0';
210 if (b != buffer)
211 fputs(buffer, f);
212 if (b != buffer && b[-1] == '\n')
213 xpos = 0;
214 } else if (line)
215 fputs(line, f);
216 }
217
218
219 /*
220 * Set everything in ptr as the rest of a physical line to be processed
221 * later.
222 */
223 static void
224 set_rest(
225 char **rest,
226 const char *ptr)
227 {
228 char *old_rest = *rest;
229
230 if (ptr == NULL || strlen(ptr) == 0) {
231 FreeAndNull(*rest);
232 return;
233 }
234 *rest = my_strdup(ptr);
235 FreeIfNeeded(old_rest);
236 }
237
238
239 /*
240 * Copy things that were left over from the last decoding into the new line.
241 * If there's a newline in the rest, copy everything up to and including that
242 * newline into the expected buffer, adjust rest and return. If there's no
243 * newline in the rest, copy all of it to the expected buffer and return.
244 *
245 * Side effects: resizes line if necessary, adjusts max_line_len
246 * accordingly.
247 *
248 * This function returns the number of characters written to the line buffer.
249 */
250 static int
251 put_rest(
252 char **rest,
253 char **line,
254 size_t *max_line_len,
255 const int offset)
256 {
257 char *my_rest = *rest;
258 char *ptr;
259 char c;
260 int put_chars = offset;
261
262 if ((ptr = my_rest) == NULL)
263 return put_chars;
264 if (strlen(my_rest) == 0) {
265 FreeAndNull(*rest);
266 return put_chars;
267 }
268
269 while ((c = *ptr++) && (c != '\n')) {
270 if ((c == '\r') && (*ptr == '\n'))
271 continue; /* step over CRLF */
272 /*
273 * Resize line if necessary. Keep in mind that we add LF and \0 later.
274 */
275 if (put_chars >= (int) *max_line_len - 2) {
276 if (*max_line_len == 0)
277 *max_line_len = LEN;
278 else
279 *max_line_len <<= 1;
280 *line = my_realloc(*line, *max_line_len);
281 }
282 (*line)[put_chars++] = c;
283 }
284 if (c == '\n') {
285 /* Look for CRLF spread over two lines. */
286 if (put_chars && (*line)[put_chars -1] == '\r')
287 --put_chars;
288 /*
289 * FIXME: Adding a newline may be not correct. At least it may
290 * be not what the author of that article intended.
291 * Unfortunately, a newline is expected at the end of a line by
292 * some other code in cook.c and even those functions invoking
293 * this one rely on it.
294 */
295 (*line)[put_chars++] = '\n';
296 set_rest(rest, ptr);
297 } else /* c == 0 */
298 /* rest is now empty */
299 FreeAndNull(*rest);
300
301 (*line)[put_chars] = '\0'; /* don't count the termining NULL! */
302 return put_chars;
303 }
304
305
306 /*
307 * Read a logical base64 encoded line into the specified line buffer.
308 * Logical lines can be split over several physical base64 encoded lines and
309 * a single physical base64 encoded line can contain several logical lines.
310 * This function keeps track of all these cases and always copies only one
311 * decoded line to the line buffer.
312 *
313 * Side effects: resizes line if necessary, adjusts max_line_len
314 * accordingly.
315 *
316 * This function returns the number of physical lines read or a negative
317 * value on error.
318 */
319 int
320 read_decoded_base64_line(
321 FILE *file,
322 char **line,
323 size_t *max_line_len,
324 const int max_lines_to_read,
325 char **rest)
326 {
327 char *buf2; /* holds the entire decoded line */
328 char *buf; /* holds the entire encoded line */
329 int count;
330 int lines_read = 0;
331 int put_chars;
332
333 /*
334 * First of all, catch everything that is left over from the last decoding.
335 * If there's a newline in that rest, copy everything up to and including
336 * that newline in the expected buffer, adjust rest and return. If there's
337 * no newline in the rest, copy all of it (modulo length of the buffer) to
338 * the expected buffer and continue as if there was no rest.
339 */
340 put_chars = put_rest(rest, line, max_line_len, 0);
341 if (put_chars && ((*line)[put_chars - 1] == '\n'))
342 return 0; /* we didn't read any new lines but filled the line */
343
344 /*
345 * At this point, either there was no rest or there was no newline in the
346 * rest. In any case, we need to read further encoded lines and decode
347 * them until we find a newline or there are no more (encoded or physical)
348 * lines in this part of the posting. To be sure, now allocate memory for
349 * the output if it wasn't already done.
350 */
351 if (*max_line_len == 0) {
352 *max_line_len = LEN;
353 *line = my_malloc(*max_line_len);
354 }
355
356 /*
357 * max_lines_to_read==0 occurs at end of an encoded part and if there was
358 * no trailing newline in the encoded text. So we put one there and exit.
359 * FIXME: Adding a newline may be not correct. At least it may be not
360 * what the author of that article intended. Unfortunately, a newline is
361 * expected at the end of a line by some other code in cook.c.
362 */
363 if (max_lines_to_read <= 0) {
364 if (put_chars) {
365 (*line)[put_chars++] = '\n';
366 (*line)[put_chars] = '\0';
367 }
368 return max_lines_to_read;
369 }
370 /*
371 * Ok, now read a new line from the original article.
372 */
373 do {
374 if ((buf = tin_fgets(file, FALSE)) == NULL) {
375 /*
376 * Premature end of file (or file error), leave loop. To prevent
377 * re-invoking of this function, set the numbers of read lines to
378 * the expected maximum that should be read at most.
379 *
380 * FIXME: Adding a newline may be not correct. At least it may be
381 * not what the author of that article intended. Unfortunately, a
382 * newline is expected at the end of a line by some other code in
383 * cook.c.
384 */
385 if (put_chars > (int) *max_line_len - 2) {
386 *max_line_len <<= 1;
387 *line = my_realloc(*line, *max_line_len);
388 }
389 (*line)[put_chars++] = '\n';
390 (*line)[put_chars] = '\0';
391 return max_lines_to_read;
392 }
393 lines_read++;
394 buf2 = my_malloc(strlen(buf) + 1); /* decoded string is always shorter than encoded string, so this is safe */
395 count = mmdecode(buf, 'b', '\0', buf2);
396 buf2[count] = '\0';
397 FreeIfNeeded(*rest);
398 *rest = buf2;
399 put_chars = put_rest(rest, line, max_line_len, put_chars);
400 if (put_chars && ((*line)[put_chars - 1] == '\n')) /* end of logical line reached */
401 return lines_read;
402 } while (lines_read < max_lines_to_read);
403 /*
404 * FIXME: Adding a newline may be not correct. At least it may be
405 * not what the author of that article intended. Unfortunately, a
406 * newline is expected at the end of a line by some other code in
407 * cook.c.
408 */
409 if (put_chars > (int) *max_line_len - 2) {
410 *max_line_len <<= 1;
411 *line = my_realloc(*line, *max_line_len);
412 }
413 if ((0 == put_chars) || ('\n' != (*line)[put_chars - 1]))
414 (*line)[put_chars++] = '\n';
415 (*line)[put_chars] = '\0';
416 return lines_read;
417 }
418
419
420 /*
421 * Read a logical quoted-printable encoded line into the specified line
422 * buffer. Quoted-printable lines can be split over several physical lines,
423 * so this function collects all affected lines, concatenates and decodes
424 * them.
425 *
426 * Side effects: resizes line if necessary, adjusts max_line_len
427 * accordingly.
428 *
429 * This function returns the number of physical lines read or a negative
430 * value on error.
431 */
432 int
433 read_decoded_qp_line(
434 FILE *file,
435 char **line, /* where to copy the decoded line */
436 size_t *max_line_len, /* (maximum) line length */
437 const int max_lines_to_read) /* don't read more physical lines than told here */
438 {
439 char *buf, *buf2;
440 char *ptr;
441 char c;
442 int buflen = LEN;
443 int count;
444 int lines_read = 0;
445 size_t chars_to_add;
446
447 buf = my_malloc(buflen); /* initial internal line buffer */
448 *buf = '\0';
449 do {
450 if ((buf2 = tin_fgets(file, FALSE)) == NULL) {
451 /*
452 * Premature end of file (or file error, leave loop. To prevent
453 * re-invocation of this function, set the numbers of read lines
454 * to the expected maximum that should be read at most.
455 */
456 lines_read = max_lines_to_read;
457 break;
458 }
459 lines_read++;
460 if ((chars_to_add = strlen(buf2)) == 0) /* Empty line, leave loop. */
461 break;
462
463 /*
464 * Strip trailing white space at the end of the line.
465 * See RFC 2045, section 6.7, #3
466 */
467 c = buf2[chars_to_add - 1];
468 while ((chars_to_add > 0) && ((c == ' ') || (c == '\t') || (c == '\n') || (c == '\r'))) {
469 --chars_to_add;
470 c = (chars_to_add > 0 ? buf2[chars_to_add - 1] : '\0');
471 }
472
473 /*
474 * '=' at the end of a line indicates a soft break meaning
475 * that the following physical line "belongs" to this one.
476 * (See RFC 2045, section 6.7, #5)
477 *
478 * Skip that equal sign now; since c holds this char, the
479 * loop is not left but the next line is read and concatenated
480 * with this one while the '=' is overwritten.
481 */
482 if (c == '=') /* c is 0 when chars_to_add is 0 so this is safe */
483 buf2[--chars_to_add] = '\0';
484
485 /*
486 * Join physical lines to a logical one; keep in mind that a LF is
487 * added afterwards.
488 */
489 if (chars_to_add > buflen - strlen(buf) - 2) {
490 buflen <<= 1;
491 buf = my_realloc(buf, buflen);
492 }
493 strncat(buf, buf2, buflen);
494 } while ((c == '=') && (lines_read < max_lines_to_read));
495 /*
496 * re-add newline and NULL termination at end of line
497 * FIXME: Adding a newline may be not correct. At least it may be not
498 * what the author of that article intended. Unfortunately, a newline is
499 * expected at the end of a line by some other code in cook.c.
500 */
501 strcat(buf, "\n");
502
503 /*
504 * Now decode complete (logical) line from buf to buf2 and copy it to the
505 * buffer where the invoking function expects it. Don't decode directly
506 * to the buffer of the other function to prevent buffer overruns and to
507 * decide if the encoding was ok.
508 */
509 buf2 = my_malloc(strlen(buf) + 1); /* Don't use realloc here, tin_fgets relies on its internal state! */
510 count = mmdecode(buf, 'q', '\0', buf2);
511
512 if (count >= 0) {
513 buf2[count] = '\0';
514 ptr = buf2;
515 } else /* error in encoding: copy raw line */
516 ptr = buf;
517
518 if (*max_line_len < strlen(ptr) + 1) {
519 *max_line_len = strlen(ptr) + 1;
520 *line = my_realloc(*line, *max_line_len);
521 }
522 strncpy(*line, ptr, *max_line_len);
523 (*line)[*max_line_len - 1] = '\0'; /* be sure to terminate string */
524 free(buf);
525 free(buf2);
526 return lines_read;
527 }