1/*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 1996,1999 by Internet Software Consortium.
4 *
5 * Permission to use, copy, modify, and distribute this software for any
6 * purpose with or without fee is hereby granted, provided that the above
7 * copyright notice and this permission notice appear in all copies.
8 *
9 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
15 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
16 */
17
18#include <sys/types.h>
19
20#include <netinet/in.h>
21#include <arpa/nameser.h>
22
23#include <errno.h>
24#include <resolv.h>
25#include <string.h>
26#include <ctype.h>
27#include <stdlib.h>
28#include <limits.h>
29
30# define SPRINTF(x) ((size_t)sprintf x)
31
32/* Data. */
33
34static const char digits[] = "0123456789";
35
36/* Forward. */
37
38static int special(int);
39static int printable(int);
40static int dn_find(const u_char *, const u_char *,
41 const u_char * const *,
42 const u_char * const *);
43static int labellen(const u_char *);
44
45/* Public. */
46
47/*%
48 * Convert an encoded domain name to printable ascii as per RFC1035.
49
50 * return:
51 *\li Number of bytes written to buffer, or -1 (with errno set)
52 *
53 * notes:
54 *\li The root is returned as "."
55 *\li All other domains are returned in non absolute form
56 */
57int
58ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
59{
60 const u_char *cp;
61 char *dn, *eom;
62 u_char c;
63 u_int n;
64 int l;
65
66 cp = src;
67 dn = dst;
68 eom = dst + dstsiz;
69
70 while ((n = *cp++) != 0) {
71 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
72 /* Some kind of compression pointer. */
73 __set_errno (EMSGSIZE);
74 return (-1);
75 }
76 if (dn != dst) {
77 if (dn >= eom) {
78 __set_errno (EMSGSIZE);
79 return (-1);
80 }
81 *dn++ = '.';
82 }
83 if ((l = labellen(cp - 1)) < 0) {
84 __set_errno (EMSGSIZE);
85 return(-1);
86 }
87 if (dn + l >= eom) {
88 __set_errno (EMSGSIZE);
89 return (-1);
90 }
91 for ((void)NULL; l > 0; l--) {
92 c = *cp++;
93 if (special(c)) {
94 if (dn + 1 >= eom) {
95 __set_errno (EMSGSIZE);
96 return (-1);
97 }
98 *dn++ = '\\';
99 *dn++ = (char)c;
100 } else if (!printable(c)) {
101 if (dn + 3 >= eom) {
102 __set_errno (EMSGSIZE);
103 return (-1);
104 }
105 *dn++ = '\\';
106 *dn++ = digits[c / 100];
107 *dn++ = digits[(c % 100) / 10];
108 *dn++ = digits[c % 10];
109 } else {
110 if (dn >= eom) {
111 __set_errno (EMSGSIZE);
112 return (-1);
113 }
114 *dn++ = (char)c;
115 }
116 }
117 }
118 if (dn == dst) {
119 if (dn >= eom) {
120 __set_errno (EMSGSIZE);
121 return (-1);
122 }
123 *dn++ = '.';
124 }
125 if (dn >= eom) {
126 __set_errno (EMSGSIZE);
127 return (-1);
128 }
129 *dn++ = '\0';
130 return (dn - dst);
131}
132libresolv_hidden_def (ns_name_ntop)
133strong_alias (ns_name_ntop, __ns_name_ntop)
134
135/*%
136 * Convert an ascii string into an encoded domain name as per RFC1035.
137 *
138 * return:
139 *
140 *\li -1 if it fails
141 *\li 1 if string was fully qualified
142 *\li 0 is string was not fully qualified
143 *
144 * notes:
145 *\li Enforces label and domain length limits.
146 */
147
148int
149ns_name_pton(const char *src, u_char *dst, size_t dstsiz)
150{
151 u_char *label, *bp, *eom;
152 int c, n, escaped;
153 char *cp;
154
155 escaped = 0;
156 bp = dst;
157 eom = dst + dstsiz;
158 label = bp++;
159
160 while ((c = *src++) != 0) {
161 if (escaped) {
162 if ((cp = strchr(digits, c)) != NULL) {
163 n = (cp - digits) * 100;
164 if ((c = *src++) == 0 ||
165 (cp = strchr(digits, c)) == NULL) {
166 __set_errno (EMSGSIZE);
167 return (-1);
168 }
169 n += (cp - digits) * 10;
170 if ((c = *src++) == 0 ||
171 (cp = strchr(digits, c)) == NULL) {
172 __set_errno (EMSGSIZE);
173 return (-1);
174 }
175 n += (cp - digits);
176 if (n > 255) {
177 __set_errno (EMSGSIZE);
178 return (-1);
179 }
180 c = n;
181 }
182 escaped = 0;
183 } else if (c == '\\') {
184 escaped = 1;
185 continue;
186 } else if (c == '.') {
187 c = (bp - label - 1);
188 if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
189 __set_errno (EMSGSIZE);
190 return (-1);
191 }
192 if (label >= eom) {
193 __set_errno (EMSGSIZE);
194 return (-1);
195 }
196 *label = c;
197 /* Fully qualified ? */
198 if (*src == '\0') {
199 if (c != 0) {
200 if (bp >= eom) {
201 __set_errno (EMSGSIZE);
202 return (-1);
203 }
204 *bp++ = '\0';
205 }
206 if ((bp - dst) > MAXCDNAME) {
207 __set_errno (EMSGSIZE);
208 return (-1);
209 }
210 return (1);
211 }
212 if (c == 0 || *src == '.') {
213 __set_errno (EMSGSIZE);
214 return (-1);
215 }
216 label = bp++;
217 continue;
218 }
219 if (bp >= eom) {
220 __set_errno (EMSGSIZE);
221 return (-1);
222 }
223 *bp++ = (u_char)c;
224 }
225 c = (bp - label - 1);
226 if ((c & NS_CMPRSFLGS) != 0) { /*%< Label too big. */
227 __set_errno (EMSGSIZE);
228 return (-1);
229 }
230 if (label >= eom) {
231 __set_errno (EMSGSIZE);
232 return (-1);
233 }
234 *label = c;
235 if (c != 0) {
236 if (bp >= eom) {
237 __set_errno (EMSGSIZE);
238 return (-1);
239 }
240 *bp++ = 0;
241 }
242 if ((bp - dst) > MAXCDNAME) { /*%< src too big */
243 __set_errno (EMSGSIZE);
244 return (-1);
245 }
246 return (0);
247}
248libresolv_hidden_def (ns_name_pton)
249
250/*%
251 * Convert a network strings labels into all lowercase.
252 *
253 * return:
254 *\li Number of bytes written to buffer, or -1 (with errno set)
255 *
256 * notes:
257 *\li Enforces label and domain length limits.
258 */
259
260int
261ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
262{
263 const u_char *cp;
264 u_char *dn, *eom;
265 u_char c;
266 u_int n;
267 int l;
268
269 cp = src;
270 dn = dst;
271 eom = dst + dstsiz;
272
273 if (dn >= eom) {
274 __set_errno (EMSGSIZE);
275 return (-1);
276 }
277 while ((n = *cp++) != 0) {
278 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
279 /* Some kind of compression pointer. */
280 __set_errno (EMSGSIZE);
281 return (-1);
282 }
283 *dn++ = n;
284 if ((l = labellen(cp - 1)) < 0) {
285 __set_errno (EMSGSIZE);
286 return (-1);
287 }
288 if (dn + l >= eom) {
289 __set_errno (EMSGSIZE);
290 return (-1);
291 }
292 for ((void)NULL; l > 0; l--) {
293 c = *cp++;
294 if (isupper(c))
295 *dn++ = tolower(c);
296 else
297 *dn++ = c;
298 }
299 }
300 *dn++ = '\0';
301 return (dn - dst);
302}
303
304/*%
305 * Unpack a domain name from a message, source may be compressed.
306 *
307 * return:
308 *\li -1 if it fails, or consumed octets if it succeeds.
309 */
310int
311ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
312 u_char *dst, size_t dstsiz)
313{
314 const u_char *srcp, *dstlim;
315 u_char *dstp;
316 int n, len, checked, l;
317
318 len = -1;
319 checked = 0;
320 dstp = dst;
321 srcp = src;
322 dstlim = dst + dstsiz;
323 if (srcp < msg || srcp >= eom) {
324 __set_errno (EMSGSIZE);
325 return (-1);
326 }
327 /* Fetch next label in domain name. */
328 while ((n = *srcp++) != 0) {
329 /* Check for indirection. */
330 switch (n & NS_CMPRSFLGS) {
331 case 0:
332 /* Limit checks. */
333 if ((l = labellen(srcp - 1)) < 0) {
334 __set_errno (EMSGSIZE);
335 return(-1);
336 }
337 if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
338 __set_errno (EMSGSIZE);
339 return (-1);
340 }
341 checked += l + 1;
342 *dstp++ = n;
343 memcpy(dstp, srcp, l);
344 dstp += l;
345 srcp += l;
346 break;
347
348 case NS_CMPRSFLGS:
349 if (srcp >= eom) {
350 __set_errno (EMSGSIZE);
351 return (-1);
352 }
353 if (len < 0)
354 len = srcp - src + 1;
355 srcp = msg + (((n & 0x3f) << 8) | (*srcp & 0xff));
356 if (srcp < msg || srcp >= eom) { /*%< Out of range. */
357 __set_errno (EMSGSIZE);
358 return (-1);
359 }
360 checked += 2;
361 /*
362 * Check for loops in the compressed name;
363 * if we've looked at the whole message,
364 * there must be a loop.
365 */
366 if (checked >= eom - msg) {
367 __set_errno (EMSGSIZE);
368 return (-1);
369 }
370 break;
371
372 default:
373 __set_errno (EMSGSIZE);
374 return (-1); /*%< flag error */
375 }
376 }
377 *dstp = '\0';
378 if (len < 0)
379 len = srcp - src;
380 return (len);
381}
382libresolv_hidden_def (ns_name_unpack)
383strong_alias (ns_name_unpack, __ns_name_unpack)
384
385/*%
386 * Pack domain name 'domain' into 'comp_dn'.
387 *
388 * return:
389 *\li Size of the compressed name, or -1.
390 *
391 * notes:
392 *\li 'dnptrs' is an array of pointers to previous compressed names.
393 *\li dnptrs[0] is a pointer to the beginning of the message. The array
394 * ends with NULL.
395 *\li 'lastdnptr' is a pointer to the end of the array pointed to
396 * by 'dnptrs'.
397 *
398 * Side effects:
399 *\li The list of pointers in dnptrs is updated for labels inserted into
400 * the message as we compress the name. If 'dnptr' is NULL, we don't
401 * try to compress names. If 'lastdnptr' is NULL, we don't update the
402 * list.
403 */
404int
405ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
406 const u_char **dnptrs, const u_char **lastdnptr)
407{
408 u_char *dstp;
409 const u_char **cpp, **lpp, *eob, *msg;
410 const u_char *srcp;
411 int n, l, first = 1;
412
413 srcp = src;
414 dstp = dst;
415 eob = dstp + dstsiz;
416 lpp = cpp = NULL;
417 if (dnptrs != NULL) {
418 if ((msg = *dnptrs++) != NULL) {
419 for (cpp = dnptrs; *cpp != NULL; cpp++)
420 (void)NULL;
421 lpp = cpp; /*%< end of list to search */
422 }
423 } else
424 msg = NULL;
425
426 /* make sure the domain we are about to add is legal */
427 l = 0;
428 do {
429 int l0;
430
431 n = *srcp;
432 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
433 __set_errno (EMSGSIZE);
434 return (-1);
435 }
436 if ((l0 = labellen(srcp)) < 0) {
437 __set_errno (EINVAL);
438 return(-1);
439 }
440 l += l0 + 1;
441 if (l > MAXCDNAME) {
442 __set_errno (EMSGSIZE);
443 return (-1);
444 }
445 srcp += l0 + 1;
446 } while (n != 0);
447
448 /* from here on we need to reset compression pointer array on error */
449 srcp = src;
450 do {
451 /* Look to see if we can use pointers. */
452 n = *srcp;
453 if (n != 0 && msg != NULL) {
454 l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
455 (const u_char * const *)lpp);
456 if (l >= 0) {
457 if (dstp + 1 >= eob) {
458 goto cleanup;
459 }
460 *dstp++ = (l >> 8) | NS_CMPRSFLGS;
461 *dstp++ = l % 256;
462 return (dstp - dst);
463 }
464 /* Not found, save it. */
465 if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
466 (dstp - msg) < 0x4000 && first) {
467 *cpp++ = dstp;
468 *cpp = NULL;
469 first = 0;
470 }
471 }
472 /* copy label to buffer */
473 if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
474 /* Should not happen. */
475 goto cleanup;
476 }
477 n = labellen(srcp);
478 if (dstp + 1 + n >= eob) {
479 goto cleanup;
480 }
481 memcpy(dstp, srcp, n + 1);
482 srcp += n + 1;
483 dstp += n + 1;
484 } while (n != 0);
485
486 if (dstp > eob) {
487cleanup:
488 if (msg != NULL)
489 *lpp = NULL;
490 __set_errno (EMSGSIZE);
491 return (-1);
492 }
493 return (dstp - dst);
494}
495libresolv_hidden_def (ns_name_pack)
496
497/*%
498 * Expand compressed domain name to presentation format.
499 *
500 * return:
501 *\li Number of bytes read out of `src', or -1 (with errno set).
502 *
503 * note:
504 *\li Root domain returns as "." not "".
505 */
506int
507ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
508 char *dst, size_t dstsiz)
509{
510 u_char tmp[NS_MAXCDNAME];
511 int n;
512
513 if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
514 return (-1);
515 if (ns_name_ntop(tmp, dst, dstsiz) == -1)
516 return (-1);
517 return (n);
518}
519libresolv_hidden_def (ns_name_uncompress)
520
521/*%
522 * Compress a domain name into wire format, using compression pointers.
523 *
524 * return:
525 *\li Number of bytes consumed in `dst' or -1 (with errno set).
526 *
527 * notes:
528 *\li 'dnptrs' is an array of pointers to previous compressed names.
529 *\li dnptrs[0] is a pointer to the beginning of the message.
530 *\li The list ends with NULL. 'lastdnptr' is a pointer to the end of the
531 * array pointed to by 'dnptrs'. Side effect is to update the list of
532 * pointers for labels inserted into the message as we compress the name.
533 *\li If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
534 * is NULL, we don't update the list.
535 */
536int
537ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
538 const u_char **dnptrs, const u_char **lastdnptr)
539{
540 u_char tmp[NS_MAXCDNAME];
541
542 if (ns_name_pton(src, tmp, sizeof tmp) == -1)
543 return (-1);
544 return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
545}
546libresolv_hidden_def (ns_name_compress)
547
548/*%
549 * Reset dnptrs so that there are no active references to pointers at or
550 * after src.
551 */
552void
553ns_name_rollback(const u_char *src, const u_char **dnptrs,
554 const u_char **lastdnptr)
555{
556 while (dnptrs < lastdnptr && *dnptrs != NULL) {
557 if (*dnptrs >= src) {
558 *dnptrs = NULL;
559 break;
560 }
561 dnptrs++;
562 }
563}
564
565/*%
566 * Advance *ptrptr to skip over the compressed name it points at.
567 *
568 * return:
569 *\li 0 on success, -1 (with errno set) on failure.
570 */
571int
572ns_name_skip(const u_char **ptrptr, const u_char *eom)
573{
574 const u_char *cp;
575 u_int n;
576
577 cp = *ptrptr;
578 while (cp < eom && (n = *cp++) != 0) {
579 /* Check for indirection. */
580 switch (n & NS_CMPRSFLGS) {
581 case 0: /*%< normal case, n == len */
582 cp += n;
583 continue;
584 case NS_CMPRSFLGS: /*%< indirection */
585 cp++;
586 break;
587 default: /*%< illegal type */
588 __set_errno (EMSGSIZE);
589 return (-1);
590 }
591 break;
592 }
593 if (cp > eom) {
594 __set_errno (EMSGSIZE);
595 return (-1);
596 }
597 *ptrptr = cp;
598 return (0);
599}
600libresolv_hidden_def (ns_name_skip)
601
602/* Private. */
603
604/*%
605 * Thinking in noninternationalized USASCII (per the DNS spec),
606 * is this character special ("in need of quoting") ?
607 *
608 * return:
609 *\li boolean.
610 */
611static int
612special(int ch) {
613 switch (ch) {
614 case 0x22: /*%< '"' */
615 case 0x2E: /*%< '.' */
616 case 0x3B: /*%< ';' */
617 case 0x5C: /*%< '\\' */
618 case 0x28: /*%< '(' */
619 case 0x29: /*%< ')' */
620 /* Special modifiers in zone files. */
621 case 0x40: /*%< '@' */
622 case 0x24: /*%< '$' */
623 return (1);
624 default:
625 return (0);
626 }
627}
628
629/*%
630 * Thinking in noninternationalized USASCII (per the DNS spec),
631 * is this character visible and not a space when printed ?
632 *
633 * return:
634 *\li boolean.
635 */
636static int
637printable(int ch) {
638 return (ch > 0x20 && ch < 0x7f);
639}
640
641/*%
642 * Thinking in noninternationalized USASCII (per the DNS spec),
643 * convert this character to lower case if it's upper case.
644 */
645static int
646mklower(int ch) {
647 if (ch >= 0x41 && ch <= 0x5A)
648 return (ch + 0x20);
649 return (ch);
650}
651
652/*%
653 * Search for the counted-label name in an array of compressed names.
654 *
655 * return:
656 *\li offset from msg if found, or -1.
657 *
658 * notes:
659 *\li dnptrs is the pointer to the first name on the list,
660 *\li not the pointer to the start of the message.
661 */
662static int
663dn_find(const u_char *domain, const u_char *msg,
664 const u_char * const *dnptrs,
665 const u_char * const *lastdnptr)
666{
667 const u_char *dn, *cp, *sp;
668 const u_char * const *cpp;
669 u_int n;
670
671 for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
672 sp = *cpp;
673 /*
674 * terminate search on:
675 * root label
676 * compression pointer
677 * unusable offset
678 */
679 while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
680 (sp - msg) < 0x4000) {
681 dn = domain;
682 cp = sp;
683 while ((n = *cp++) != 0) {
684 /*
685 * check for indirection
686 */
687 switch (n & NS_CMPRSFLGS) {
688 case 0: /*%< normal case, n == len */
689 n = labellen(cp - 1); /*%< XXX */
690 if (n != *dn++)
691 goto next;
692
693 for ((void)NULL; n > 0; n--)
694 if (mklower(*dn++) !=
695 mklower(*cp++))
696 goto next;
697 /* Is next root for both ? */
698 if (*dn == '\0' && *cp == '\0')
699 return (sp - msg);
700 if (*dn)
701 continue;
702 goto next;
703 case NS_CMPRSFLGS: /*%< indirection */
704 cp = msg + (((n & 0x3f) << 8) | *cp);
705 break;
706
707 default: /*%< illegal type */
708 __set_errno (EMSGSIZE);
709 return (-1);
710 }
711 }
712 next: ;
713 sp += *sp + 1;
714 }
715 }
716 __set_errno (ENOENT);
717 return (-1);
718}
719
720/* Return the length of the encoded label starting at LP, or -1 for
721 compression references and extended label types. */
722static int
723labellen (const unsigned char *lp)
724{
725 if (*lp <= 63)
726 return *lp;
727 return -1;
728}
729
730/*! \file */
731