xref: /freebsd/contrib/unbound/sldns/parseutil.c (revision 3fc36ee018bb836bd1796067cf4ef8683f166ebc)
1 /*
2  * parseutil.c - parse utilities for string and wire conversion
3  *
4  * (c) NLnet Labs, 2004-2006
5  *
6  * See the file LICENSE for the license
7  */
8 /**
9  * \file
10  *
11  * Utility functions for parsing, base32(DNS variant) and base64 encoding
12  * and decoding, Hex, Time units, Escape codes.
13  */
14 
15 #include "config.h"
16 #include "sldns/parseutil.h"
17 #include <sys/time.h>
18 #include <time.h>
19 #include <ctype.h>
20 
21 sldns_lookup_table *
22 sldns_lookup_by_name(sldns_lookup_table *table, const char *name)
23 {
24         while (table->name != NULL) {
25                 if (strcasecmp(name, table->name) == 0)
26                         return table;
27                 table++;
28         }
29         return NULL;
30 }
31 
32 sldns_lookup_table *
33 sldns_lookup_by_id(sldns_lookup_table *table, int id)
34 {
35         while (table->name != NULL) {
36                 if (table->id == id)
37                         return table;
38                 table++;
39         }
40         return NULL;
41 }
42 
43 /* Number of days per month (except for February in leap years). */
44 static const int mdays[] = {
45 	31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
46 };
47 
48 #define LDNS_MOD(x,y) (((x) % (y) < 0) ? ((x) % (y) + (y)) : ((x) % (y)))
49 #define LDNS_DIV(x,y) (((x) % (y) < 0) ? ((x) / (y) -  1 ) : ((x) / (y)))
50 
51 static int
52 is_leap_year(int year)
53 {
54 	return LDNS_MOD(year,   4) == 0 && (LDNS_MOD(year, 100) != 0
55 	    || LDNS_MOD(year, 400) == 0);
56 }
57 
58 static int
59 leap_days(int y1, int y2)
60 {
61 	--y1;
62 	--y2;
63 	return (LDNS_DIV(y2,   4) - LDNS_DIV(y1,   4)) -
64 	       (LDNS_DIV(y2, 100) - LDNS_DIV(y1, 100)) +
65 	       (LDNS_DIV(y2, 400) - LDNS_DIV(y1, 400));
66 }
67 
68 /*
69  * Code adapted from Python 2.4.1 sources (Lib/calendar.py).
70  */
71 time_t
72 sldns_mktime_from_utc(const struct tm *tm)
73 {
74 	int year = 1900 + tm->tm_year;
75 	time_t days = 365 * ((time_t) year - 1970) + leap_days(1970, year);
76 	time_t hours;
77 	time_t minutes;
78 	time_t seconds;
79 	int i;
80 
81 	for (i = 0; i < tm->tm_mon; ++i) {
82 		days += mdays[i];
83 	}
84 	if (tm->tm_mon > 1 && is_leap_year(year)) {
85 		++days;
86 	}
87 	days += tm->tm_mday - 1;
88 
89 	hours = days * 24 + tm->tm_hour;
90 	minutes = hours * 60 + tm->tm_min;
91 	seconds = minutes * 60 + tm->tm_sec;
92 
93 	return seconds;
94 }
95 
96 #if SIZEOF_TIME_T <= 4
97 
98 static void
99 sldns_year_and_yday_from_days_since_epoch(int64_t days, struct tm *result)
100 {
101 	int year = 1970;
102 	int new_year;
103 
104 	while (days < 0 || days >= (int64_t) (is_leap_year(year) ? 366 : 365)) {
105 		new_year = year + (int) LDNS_DIV(days, 365);
106 		days -= (new_year - year) * 365;
107 		days -= leap_days(year, new_year);
108 		year  = new_year;
109 	}
110 	result->tm_year = year;
111 	result->tm_yday = (int) days;
112 }
113 
114 /* Number of days per month in a leap year. */
115 static const int leap_year_mdays[] = {
116 	31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
117 };
118 
119 static void
120 sldns_mon_and_mday_from_year_and_yday(struct tm *result)
121 {
122 	int idays = result->tm_yday;
123 	const int *mon_lengths = is_leap_year(result->tm_year) ?
124 					leap_year_mdays : mdays;
125 
126 	result->tm_mon = 0;
127 	while  (idays >= mon_lengths[result->tm_mon]) {
128 		idays -= mon_lengths[result->tm_mon++];
129 	}
130 	result->tm_mday = idays + 1;
131 }
132 
133 static void
134 sldns_wday_from_year_and_yday(struct tm *result)
135 {
136 	result->tm_wday = 4 /* 1-1-1970 was a thursday */
137 			+ LDNS_MOD((result->tm_year - 1970), 7) * LDNS_MOD(365, 7)
138 			+ leap_days(1970, result->tm_year)
139 			+ result->tm_yday;
140 	result->tm_wday = LDNS_MOD(result->tm_wday, 7);
141 	if (result->tm_wday < 0) {
142 		result->tm_wday += 7;
143 	}
144 }
145 
146 static struct tm *
147 sldns_gmtime64_r(int64_t clock, struct tm *result)
148 {
149 	result->tm_isdst = 0;
150 	result->tm_sec   = (int) LDNS_MOD(clock, 60);
151 	clock            =       LDNS_DIV(clock, 60);
152 	result->tm_min   = (int) LDNS_MOD(clock, 60);
153 	clock            =       LDNS_DIV(clock, 60);
154 	result->tm_hour  = (int) LDNS_MOD(clock, 24);
155 	clock            =       LDNS_DIV(clock, 24);
156 
157 	sldns_year_and_yday_from_days_since_epoch(clock, result);
158 	sldns_mon_and_mday_from_year_and_yday(result);
159 	sldns_wday_from_year_and_yday(result);
160 	result->tm_year -= 1900;
161 
162 	return result;
163 }
164 
165 #endif /* SIZEOF_TIME_T <= 4 */
166 
167 static int64_t
168 sldns_serial_arithmitics_time(int32_t time, time_t now)
169 {
170 	int32_t offset = time - (int32_t) now;
171 	return (int64_t) now + offset;
172 }
173 
174 struct tm *
175 sldns_serial_arithmitics_gmtime_r(int32_t time, time_t now, struct tm *result)
176 {
177 #if SIZEOF_TIME_T <= 4
178 	int64_t secs_since_epoch = sldns_serial_arithmitics_time(time, now);
179 	return  sldns_gmtime64_r(secs_since_epoch, result);
180 #else
181 	time_t  secs_since_epoch = sldns_serial_arithmitics_time(time, now);
182 	return  gmtime_r(&secs_since_epoch, result);
183 #endif
184 }
185 
186 int
187 sldns_hexdigit_to_int(char ch)
188 {
189 	switch (ch) {
190 	case '0': return 0;
191 	case '1': return 1;
192 	case '2': return 2;
193 	case '3': return 3;
194 	case '4': return 4;
195 	case '5': return 5;
196 	case '6': return 6;
197 	case '7': return 7;
198 	case '8': return 8;
199 	case '9': return 9;
200 	case 'a': case 'A': return 10;
201 	case 'b': case 'B': return 11;
202 	case 'c': case 'C': return 12;
203 	case 'd': case 'D': return 13;
204 	case 'e': case 'E': return 14;
205 	case 'f': case 'F': return 15;
206 	default:
207 		return -1;
208 	}
209 }
210 
211 uint32_t
212 sldns_str2period(const char *nptr, const char **endptr)
213 {
214 	int sign = 0;
215 	uint32_t i = 0;
216 	uint32_t seconds = 0;
217 
218 	for(*endptr = nptr; **endptr; (*endptr)++) {
219 		switch (**endptr) {
220 			case ' ':
221 			case '\t':
222 				break;
223 			case '-':
224 				if(sign == 0) {
225 					sign = -1;
226 				} else {
227 					return seconds;
228 				}
229 				break;
230 			case '+':
231 				if(sign == 0) {
232 					sign = 1;
233 				} else {
234 					return seconds;
235 				}
236 				break;
237 			case 's':
238 			case 'S':
239 				seconds += i;
240 				i = 0;
241 				break;
242 			case 'm':
243 			case 'M':
244 				seconds += i * 60;
245 				i = 0;
246 				break;
247 			case 'h':
248 			case 'H':
249 				seconds += i * 60 * 60;
250 				i = 0;
251 				break;
252 			case 'd':
253 			case 'D':
254 				seconds += i * 60 * 60 * 24;
255 				i = 0;
256 				break;
257 			case 'w':
258 			case 'W':
259 				seconds += i * 60 * 60 * 24 * 7;
260 				i = 0;
261 				break;
262 			case '0':
263 			case '1':
264 			case '2':
265 			case '3':
266 			case '4':
267 			case '5':
268 			case '6':
269 			case '7':
270 			case '8':
271 			case '9':
272 				i *= 10;
273 				i += (**endptr - '0');
274 				break;
275 			default:
276 				seconds += i;
277 				/* disregard signedness */
278 				return seconds;
279 		}
280 	}
281 	seconds += i;
282 	/* disregard signedness */
283 	return seconds;
284 }
285 
286 int
287 sldns_parse_escape(uint8_t *ch_p, const char** str_p)
288 {
289 	uint16_t val;
290 
291 	if ((*str_p)[0] && isdigit((unsigned char)(*str_p)[0]) &&
292 	    (*str_p)[1] && isdigit((unsigned char)(*str_p)[1]) &&
293 	    (*str_p)[2] && isdigit((unsigned char)(*str_p)[2])) {
294 
295 		val = (uint16_t)(((*str_p)[0] - '0') * 100 +
296 				 ((*str_p)[1] - '0') *  10 +
297 				 ((*str_p)[2] - '0'));
298 
299 		if (val > 255) {
300 			goto error;
301 		}
302 		*ch_p = (uint8_t)val;
303 		*str_p += 3;
304 		return 1;
305 
306 	} else if ((*str_p)[0] && !isdigit((unsigned char)(*str_p)[0])) {
307 
308 		*ch_p = (uint8_t)*(*str_p)++;
309 		return 1;
310 	}
311 error:
312 	*str_p = NULL;
313 	return 0; /* LDNS_WIREPARSE_ERR_SYNTAX_BAD_ESCAPE */
314 }
315 
316 /** parse one character, with escape codes */
317 int
318 sldns_parse_char(uint8_t *ch_p, const char** str_p)
319 {
320 	switch (**str_p) {
321 
322 	case '\0':	return 0;
323 
324 	case '\\':	*str_p += 1;
325 			return sldns_parse_escape(ch_p, str_p);
326 
327 	default:	*ch_p = (uint8_t)*(*str_p)++;
328 			return 1;
329 	}
330 }
331 
332 size_t sldns_b32_ntop_calculate_size(size_t src_data_length)
333 {
334 	return src_data_length == 0 ? 0 : ((src_data_length - 1) / 5 + 1) * 8;
335 }
336 
337 size_t sldns_b32_ntop_calculate_size_no_padding(size_t src_data_length)
338 {
339 	return ((src_data_length + 3) * 8 / 5) - 4;
340 }
341 
342 static int
343 sldns_b32_ntop_base(const uint8_t* src, size_t src_sz, char* dst, size_t dst_sz,
344 	int extended_hex, int add_padding)
345 {
346 	size_t ret_sz;
347 	const char* b32 = extended_hex ?  "0123456789abcdefghijklmnopqrstuv"
348 					: "abcdefghijklmnopqrstuvwxyz234567";
349 
350 	size_t c = 0; /* c is used to carry partial base32 character over
351 		       * byte boundaries for sizes with a remainder.
352 		       * (i.e. src_sz % 5 != 0)
353 		       */
354 
355 	ret_sz = add_padding ? sldns_b32_ntop_calculate_size(src_sz)
356 			     : sldns_b32_ntop_calculate_size_no_padding(src_sz);
357 
358 	/* Do we have enough space? */
359 	if (dst_sz < ret_sz + 1)
360 		return -1;
361 
362 	/* We know the size; terminate the string */
363 	dst[ret_sz] = '\0';
364 
365 	/* First process all chunks of five */
366 	while (src_sz >= 5) {
367 		/* 00000... ........ ........ ........ ........ */
368 		dst[0] = b32[(src[0]       ) >> 3];
369 
370 		/* .....111 11...... ........ ........ ........ */
371 		dst[1] = b32[(src[0] & 0x07) << 2 | src[1] >> 6];
372 
373 		/* ........ ..22222. ........ ........ ........ */
374 		dst[2] = b32[(src[1] & 0x3e) >> 1];
375 
376 		/* ........ .......3 3333.... ........ ........ */
377 		dst[3] = b32[(src[1] & 0x01) << 4 | src[2] >> 4];
378 
379 		/* ........ ........ ....4444 4....... ........ */
380 		dst[4] = b32[(src[2] & 0x0f) << 1 | src[3] >> 7];
381 
382 		/* ........ ........ ........ .55555.. ........ */
383 		dst[5] = b32[(src[3] & 0x7c) >> 2];
384 
385 		/* ........ ........ ........ ......66 666..... */
386 		dst[6] = b32[(src[3] & 0x03) << 3 | src[4] >> 5];
387 
388 		/* ........ ........ ........ ........ ...77777 */
389 		dst[7] = b32[(src[4] & 0x1f)     ];
390 
391 		src_sz -= 5;
392 		src    += 5;
393 		dst    += 8;
394 	}
395 	/* Process what remains */
396 	switch (src_sz) {
397 	case 4: /* ........ ........ ........ ......66 666..... */
398 		dst[6] = b32[(src[3] & 0x03) << 3];
399 
400 		/* ........ ........ ........ .55555.. ........ */
401 		dst[5] = b32[(src[3] & 0x7c) >> 2];
402 
403 		/* ........ ........ ....4444 4....... ........ */
404 			 c =  src[3]         >> 7 ;
405 	case 3: dst[4] = b32[(src[2] & 0x0f) << 1 | c];
406 
407 		/* ........ .......3 3333.... ........ ........ */
408 			 c =  src[2]         >> 4 ;
409 	case 2:	dst[3] = b32[(src[1] & 0x01) << 4 | c];
410 
411 		/* ........ ..22222. ........ ........ ........ */
412 		dst[2] = b32[(src[1] & 0x3e) >> 1];
413 
414 		/* .....111 11...... ........ ........ ........ */
415 			 c =  src[1]         >> 6 ;
416 	case 1:	dst[1] = b32[(src[0] & 0x07) << 2 | c];
417 
418 		/* 00000... ........ ........ ........ ........ */
419 		dst[0] = b32[ src[0]         >> 3];
420 	}
421 	/* Add padding */
422 	if (add_padding) {
423 		switch (src_sz) {
424 			case 1: dst[2] = '=';
425 				dst[3] = '=';
426 			case 2: dst[4] = '=';
427 			case 3: dst[5] = '=';
428 				dst[6] = '=';
429 			case 4: dst[7] = '=';
430 		}
431 	}
432 	return (int)ret_sz;
433 }
434 
435 int
436 sldns_b32_ntop(const uint8_t* src, size_t src_sz, char* dst, size_t dst_sz)
437 {
438 	return sldns_b32_ntop_base(src, src_sz, dst, dst_sz, 0, 1);
439 }
440 
441 int
442 sldns_b32_ntop_extended_hex(const uint8_t* src, size_t src_sz,
443 		char* dst, size_t dst_sz)
444 {
445 	return sldns_b32_ntop_base(src, src_sz, dst, dst_sz, 1, 1);
446 }
447 
448 size_t sldns_b32_pton_calculate_size(size_t src_text_length)
449 {
450 	return src_text_length * 5 / 8;
451 }
452 
453 static int
454 sldns_b32_pton_base(const char* src, size_t src_sz, uint8_t* dst, size_t dst_sz,
455 	int extended_hex, int check_padding)
456 {
457 	size_t i = 0;
458 	char ch = '\0';
459 	uint8_t buf[8];
460 	uint8_t* start = dst;
461 
462 	while (src_sz) {
463 		/* Collect 8 characters in buf (if possible) */
464 		for (i = 0; i < 8; i++) {
465 
466 			do {
467 				ch = *src++;
468 				--src_sz;
469 
470 			} while (isspace((unsigned char)ch) && src_sz > 0);
471 
472 			if (ch == '=' || ch == '\0')
473 				break;
474 
475 			else if (extended_hex)
476 
477 				if (ch >= '0' && ch <= '9')
478 					buf[i] = (uint8_t)ch - '0';
479 				else if (ch >= 'a' && ch <= 'v')
480 					buf[i] = (uint8_t)ch - 'a' + 10;
481 				else if (ch >= 'A' && ch <= 'V')
482 					buf[i] = (uint8_t)ch - 'A' + 10;
483 				else
484 					return -1;
485 
486 			else if (ch >= 'a' && ch <= 'z')
487 				buf[i] = (uint8_t)ch - 'a';
488 			else if (ch >= 'A' && ch <= 'Z')
489 				buf[i] = (uint8_t)ch - 'A';
490 			else if (ch >= '2' && ch <= '7')
491 				buf[i] = (uint8_t)ch - '2' + 26;
492 			else
493 				return -1;
494 		}
495 		/* Less that 8 characters. We're done. */
496 		if (i < 8)
497 			break;
498 
499 		/* Enough space available at the destination? */
500 		if (dst_sz < 5)
501 			return -1;
502 
503 		/* 00000... ........ ........ ........ ........ */
504 		/* .....111 11...... ........ ........ ........ */
505 		dst[0] = buf[0] << 3 | buf[1] >> 2;
506 
507 		/* .....111 11...... ........ ........ ........ */
508 		/* ........ ..22222. ........ ........ ........ */
509 		/* ........ .......3 3333.... ........ ........ */
510 		dst[1] = buf[1] << 6 | buf[2] << 1 | buf[3] >> 4;
511 
512 		/* ........ .......3 3333.... ........ ........ */
513 		/* ........ ........ ....4444 4....... ........ */
514 		dst[2] = buf[3] << 4 | buf[4] >> 1;
515 
516 		/* ........ ........ ....4444 4....... ........ */
517 		/* ........ ........ ........ .55555.. ........ */
518 		/* ........ ........ ........ ......66 666..... */
519 		dst[3] = buf[4] << 7 | buf[5] << 2 | buf[6] >> 3;
520 
521 		/* ........ ........ ........ ......66 666..... */
522 		/* ........ ........ ........ ........ ...77777 */
523 		dst[4] = buf[6] << 5 | buf[7];
524 
525 		dst += 5;
526 		dst_sz -= 5;
527 	}
528 	/* Not ending on a eight byte boundary? */
529 	if (i > 0 && i < 8) {
530 
531 		/* Enough space available at the destination? */
532 		if (dst_sz < (i + 1) / 2)
533 			return -1;
534 
535 		switch (i) {
536 		case 7: /* ........ ........ ........ ......66 666..... */
537 			/* ........ ........ ........ .55555.. ........ */
538 			/* ........ ........ ....4444 4....... ........ */
539 			dst[3] = buf[4] << 7 | buf[5] << 2 | buf[6] >> 3;
540 
541 		case 5: /* ........ ........ ....4444 4....... ........ */
542 			/* ........ .......3 3333.... ........ ........ */
543 			dst[2] = buf[3] << 4 | buf[4] >> 1;
544 
545 		case 4: /* ........ .......3 3333.... ........ ........ */
546 			/* ........ ..22222. ........ ........ ........ */
547 			/* .....111 11...... ........ ........ ........ */
548 			dst[1] = buf[1] << 6 | buf[2] << 1 | buf[3] >> 4;
549 
550 		case 2: /* .....111 11...... ........ ........ ........ */
551 			/* 00000... ........ ........ ........ ........ */
552 			dst[0] = buf[0] << 3 | buf[1] >> 2;
553 
554 			break;
555 
556 		default:
557 			return -1;
558 		}
559 		dst += (i + 1) / 2;
560 
561 		if (check_padding) {
562 			/* Check remaining padding characters */
563 			if (ch != '=')
564 				return -1;
565 
566 			/* One down, 8 - i - 1 more to come... */
567 			for (i = 8 - i - 1; i > 0; i--) {
568 
569 				do {
570 					if (src_sz == 0)
571 						return -1;
572 					ch = *src++;
573 					src_sz--;
574 
575 				} while (isspace((unsigned char)ch));
576 
577 				if (ch != '=')
578 					return -1;
579 			}
580 		}
581 	}
582 	return dst - start;
583 }
584 
585 int
586 sldns_b32_pton(const char* src, size_t src_sz, uint8_t* dst, size_t dst_sz)
587 {
588 	return sldns_b32_pton_base(src, src_sz, dst, dst_sz, 0, 1);
589 }
590 
591 int
592 sldns_b32_pton_extended_hex(const char* src, size_t src_sz,
593 		uint8_t* dst, size_t dst_sz)
594 {
595 	return sldns_b32_pton_base(src, src_sz, dst, dst_sz, 1, 1);
596 }
597 
598 size_t sldns_b64_ntop_calculate_size(size_t srcsize)
599 {
600 	return ((((srcsize + 2) / 3) * 4) + 1);
601 }
602 
603 /* RFC 1521, section 5.2.
604  *
605  * The encoding process represents 24-bit groups of input bits as output
606  * strings of 4 encoded characters. Proceeding from left to right, a
607  * 24-bit input group is formed by concatenating 3 8-bit input groups.
608  * These 24 bits are then treated as 4 concatenated 6-bit groups, each
609  * of which is translated into a single digit in the base64 alphabet.
610  *
611  * This routine does not insert spaces or linebreaks after 76 characters.
612  */
613 int sldns_b64_ntop(uint8_t const *src, size_t srclength,
614 	char *target, size_t targsize)
615 {
616 	const char* b64 =
617 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
618 	const char pad64 = '=';
619 	size_t i = 0, o = 0;
620 	if(targsize < sldns_b64_ntop_calculate_size(srclength))
621 		return -1;
622 	/* whole chunks: xxxxxxyy yyyyzzzz zzwwwwww */
623 	while(i+3 <= srclength) {
624 		if(o+4 > targsize) return -1;
625 		target[o] = b64[src[i] >> 2];
626 		target[o+1] = b64[ ((src[i]&0x03)<<4) | (src[i+1]>>4) ];
627 		target[o+2] = b64[ ((src[i+1]&0x0f)<<2) | (src[i+2]>>6) ];
628 		target[o+3] = b64[ (src[i+2]&0x3f) ];
629 		i += 3;
630 		o += 4;
631 	}
632 	/* remainder */
633 	switch(srclength - i) {
634 	case 2:
635 		/* two at end, converted into A B C = */
636 		target[o] = b64[src[i] >> 2];
637 		target[o+1] = b64[ ((src[i]&0x03)<<4) | (src[i+1]>>4) ];
638 		target[o+2] = b64[ ((src[i+1]&0x0f)<<2) ];
639 		target[o+3] = pad64;
640 		/* i += 2; */
641 		o += 4;
642 		break;
643 	case 1:
644 		/* one at end, converted into A B = = */
645 		target[o] = b64[src[i] >> 2];
646 		target[o+1] = b64[ ((src[i]&0x03)<<4) ];
647 		target[o+2] = pad64;
648 		target[o+3] = pad64;
649 		/* i += 1; */
650 		o += 4;
651 		break;
652 	case 0:
653 	default:
654 		/* nothing */
655 		break;
656 	}
657 	/* assert: i == srclength */
658 	if(o+1 > targsize) return -1;
659 	target[o] = 0;
660 	return (int)o;
661 }
662 
663 size_t sldns_b64_pton_calculate_size(size_t srcsize)
664 {
665 	return (((((srcsize + 3) / 4) * 3)) + 1);
666 }
667 
668 int sldns_b64_pton(char const *src, uint8_t *target, size_t targsize)
669 {
670 	const uint8_t pad64 = 64; /* is 64th in the b64 array */
671 	const char* s = src;
672 	uint8_t in[4];
673 	size_t o = 0, incount = 0;
674 
675 	while(*s) {
676 		/* skip any character that is not base64 */
677 		/* conceptually we do:
678 		const char* b64 =      pad'=' is appended to array
679 		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=";
680 		const char* d = strchr(b64, *s++);
681 		and use d-b64;
682 		*/
683 		char d = *s++;
684 		if(d <= 'Z' && d >= 'A')
685 			d -= 'A';
686 		else if(d <= 'z' && d >= 'a')
687 			d = d - 'a' + 26;
688 		else if(d <= '9' && d >= '0')
689 			d = d - '0' + 52;
690 		else if(d == '+')
691 			d = 62;
692 		else if(d == '/')
693 			d = 63;
694 		else if(d == '=')
695 			d = 64;
696 		else	continue;
697 		in[incount++] = (uint8_t)d;
698 		if(incount != 4)
699 			continue;
700 		/* process whole block of 4 characters into 3 output bytes */
701 		if(in[3] == pad64 && in[2] == pad64) { /* A B = = */
702 			if(o+1 > targsize)
703 				return -1;
704 			target[o] = (in[0]<<2) | ((in[1]&0x30)>>4);
705 			o += 1;
706 			break; /* we are done */
707 		} else if(in[3] == pad64) { /* A B C = */
708 			if(o+2 > targsize)
709 				return -1;
710 			target[o] = (in[0]<<2) | ((in[1]&0x30)>>4);
711 			target[o+1]= ((in[1]&0x0f)<<4) | ((in[2]&0x3c)>>2);
712 			o += 2;
713 			break; /* we are done */
714 		} else {
715 			if(o+3 > targsize)
716 				return -1;
717 			/* write xxxxxxyy yyyyzzzz zzwwwwww */
718 			target[o] = (in[0]<<2) | ((in[1]&0x30)>>4);
719 			target[o+1]= ((in[1]&0x0f)<<4) | ((in[2]&0x3c)>>2);
720 			target[o+2]= ((in[2]&0x03)<<6) | in[3];
721 			o += 3;
722 		}
723 		incount = 0;
724 	}
725 	return (int)o;
726 }
727