1/*	$NetBSD: ns_name.c,v 1.1.1.2 2012/09/09 16:08:04 christos Exp $	*/
2
3/*
4 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
5 * Copyright (c) 1996,1999 by Internet Software Consortium.
6 *
7 * Permission to use, copy, modify, and distribute this software for any
8 * purpose with or without fee is hereby granted, provided that the above
9 * copyright notice and this permission notice appear in all copies.
10 *
11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
12 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
13 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
14 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
15 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
16 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
17 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
18 */
19
20#ifndef lint
21static const char rcsid[] = "Id: ns_name.c,v 1.11 2009/01/23 19:59:16 each Exp ";
22#endif
23
24#include "port_before.h"
25
26#include <sys/types.h>
27
28#include <netinet/in.h>
29#include <arpa/nameser.h>
30
31#include <errno.h>
32#include <resolv.h>
33#include <string.h>
34#include <ctype.h>
35#include <stdlib.h>
36#include <limits.h>
37
38#include "port_after.h"
39
40#ifdef SPRINTF_CHAR
41# define SPRINTF(x) strlen(sprintf/**/x)
42#else
43# define SPRINTF(x) ((size_t)sprintf x)
44#endif
45
46#define NS_TYPE_ELT			0x40 /*%< EDNS0 extended label type */
47#define DNS_LABELTYPE_BITSTRING		0x41
48
49/* Data. */
50
51static const char	digits[] = "0123456789";
52
53static const char digitvalue[256] = {
54	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,	/*16*/
55	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*32*/
56	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*48*/
57	 0,  1,  2,  3,  4,  5,  6,  7,  8,  9, -1, -1, -1, -1, -1, -1, /*64*/
58	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*80*/
59	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*96*/
60	-1, 10, 11, 12, 13, 14, 15, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*112*/
61	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*128*/
62	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
63	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
64	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
65	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
66	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
67	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
68	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
69	-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, /*256*/
70};
71
72/* Forward. */
73
74static int		special(int);
75static int		printable(int);
76static int		dn_find(const u_char *, const u_char *,
77				const u_char * const *,
78				const u_char * const *);
79static int		encode_bitsring(const char **, const char *,
80					unsigned char **, unsigned char **,
81					unsigned const char *);
82static int		labellen(const u_char *);
83static int		decode_bitstring(const unsigned char **,
84					 char *, const char *);
85
86/* Public. */
87
88/*%
89 *	Convert an encoded domain name to printable ascii as per RFC1035.
90
91 * return:
92 *\li	Number of bytes written to buffer, or -1 (with errno set)
93 *
94 * notes:
95 *\li	The root is returned as "."
96 *\li	All other domains are returned in non absolute form
97 */
98int
99ns_name_ntop(const u_char *src, char *dst, size_t dstsiz)
100{
101	const u_char *cp;
102	char *dn, *eom;
103	u_char c;
104	u_int n;
105	int l;
106
107	cp = src;
108	dn = dst;
109	eom = dst + dstsiz;
110
111	while ((n = *cp++) != 0) {
112		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
113			/* Some kind of compression pointer. */
114			errno = EMSGSIZE;
115			return (-1);
116		}
117		if (dn != dst) {
118			if (dn >= eom) {
119				errno = EMSGSIZE;
120				return (-1);
121			}
122			*dn++ = '.';
123		}
124		if ((l = labellen(cp - 1)) < 0) {
125			errno = EMSGSIZE; /*%< XXX */
126			return (-1);
127		}
128		if (dn + l >= eom) {
129			errno = EMSGSIZE;
130			return (-1);
131		}
132		if ((n & NS_CMPRSFLGS) == NS_TYPE_ELT) {
133			int m;
134
135			if (n != DNS_LABELTYPE_BITSTRING) {
136				/* XXX: labellen should reject this case */
137				errno = EINVAL;
138				return (-1);
139			}
140			if ((m = decode_bitstring(&cp, dn, eom)) < 0)
141			{
142				errno = EMSGSIZE;
143				return (-1);
144			}
145			dn += m;
146			continue;
147		}
148		for ((void)NULL; l > 0; l--) {
149			c = *cp++;
150			if (special(c)) {
151				if (dn + 1 >= eom) {
152					errno = EMSGSIZE;
153					return (-1);
154				}
155				*dn++ = '\\';
156				*dn++ = (char)c;
157			} else if (!printable(c)) {
158				if (dn + 3 >= eom) {
159					errno = EMSGSIZE;
160					return (-1);
161				}
162				*dn++ = '\\';
163				*dn++ = digits[c / 100];
164				*dn++ = digits[(c % 100) / 10];
165				*dn++ = digits[c % 10];
166			} else {
167				if (dn >= eom) {
168					errno = EMSGSIZE;
169					return (-1);
170				}
171				*dn++ = (char)c;
172			}
173		}
174	}
175	if (dn == dst) {
176		if (dn >= eom) {
177			errno = EMSGSIZE;
178			return (-1);
179		}
180		*dn++ = '.';
181	}
182	if (dn >= eom) {
183		errno = EMSGSIZE;
184		return (-1);
185	}
186	*dn++ = '\0';
187	return (dn - dst);
188}
189
190/*%
191 *	Convert a ascii string into an encoded domain name as per RFC1035.
192 *
193 * return:
194 *
195 *\li	-1 if it fails
196 *\li	1 if string was fully qualified
197 *\li	0 is string was not fully qualified
198 *
199 * notes:
200 *\li	Enforces label and domain length limits.
201 */
202int
203ns_name_pton(const char *src, u_char *dst, size_t dstsiz) {
204	return (ns_name_pton2(src, dst, dstsiz, NULL));
205}
206
207/*
208 * ns_name_pton2(src, dst, dstsiz, *dstlen)
209 *	Convert a ascii string into an encoded domain name as per RFC1035.
210 * return:
211 *	-1 if it fails
212 *	1 if string was fully qualified
213 *	0 is string was not fully qualified
214 * side effects:
215 *	fills in *dstlen (if non-NULL)
216 * notes:
217 *	Enforces label and domain length limits.
218 */
219int
220ns_name_pton2(const char *src, u_char *dst, size_t dstsiz, size_t *dstlen) {
221	u_char *label, *bp, *eom;
222	int c, n, escaped, e = 0;
223	char *cp;
224
225	escaped = 0;
226	bp = dst;
227	eom = dst + dstsiz;
228	label = bp++;
229
230	while ((c = *src++) != 0) {
231		if (escaped) {
232			if (c == '[') { /*%< start a bit string label */
233				if ((cp = strchr(src, ']')) == NULL) {
234					errno = EINVAL; /*%< ??? */
235					return (-1);
236				}
237				if ((e = encode_bitsring(&src, cp + 2,
238							 &label, &bp, eom))
239				    != 0) {
240					errno = e;
241					return (-1);
242				}
243				escaped = 0;
244				label = bp++;
245				if ((c = *src++) == 0)
246					goto done;
247				else if (c != '.') {
248					errno = EINVAL;
249					return	(-1);
250				}
251				continue;
252			}
253			else if ((cp = strchr(digits, c)) != NULL) {
254				n = (cp - digits) * 100;
255				if ((c = *src++) == 0 ||
256				    (cp = strchr(digits, c)) == NULL) {
257					errno = EMSGSIZE;
258					return (-1);
259				}
260				n += (cp - digits) * 10;
261				if ((c = *src++) == 0 ||
262				    (cp = strchr(digits, c)) == NULL) {
263					errno = EMSGSIZE;
264					return (-1);
265				}
266				n += (cp - digits);
267				if (n > 255) {
268					errno = EMSGSIZE;
269					return (-1);
270				}
271				c = n;
272			}
273			escaped = 0;
274		} else if (c == '\\') {
275			escaped = 1;
276			continue;
277		} else if (c == '.') {
278			c = (bp - label - 1);
279			if ((c & NS_CMPRSFLGS) != 0) {	/*%< Label too big. */
280				errno = EMSGSIZE;
281				return (-1);
282			}
283			if (label >= eom) {
284				errno = EMSGSIZE;
285				return (-1);
286			}
287			*label = c;
288			/* Fully qualified ? */
289			if (*src == '\0') {
290				if (c != 0) {
291					if (bp >= eom) {
292						errno = EMSGSIZE;
293						return (-1);
294					}
295					*bp++ = '\0';
296				}
297				if ((bp - dst) > MAXCDNAME) {
298					errno = EMSGSIZE;
299					return (-1);
300				}
301				if (dstlen != NULL)
302					*dstlen = (bp - dst);
303				return (1);
304			}
305			if (c == 0 || *src == '.') {
306				errno = EMSGSIZE;
307				return (-1);
308			}
309			label = bp++;
310			continue;
311		}
312		if (bp >= eom) {
313			errno = EMSGSIZE;
314			return (-1);
315		}
316		*bp++ = (u_char)c;
317	}
318	c = (bp - label - 1);
319	if ((c & NS_CMPRSFLGS) != 0) {		/*%< Label too big. */
320		errno = EMSGSIZE;
321		return (-1);
322	}
323  done:
324	if (label >= eom) {
325		errno = EMSGSIZE;
326		return (-1);
327	}
328	*label = c;
329	if (c != 0) {
330		if (bp >= eom) {
331			errno = EMSGSIZE;
332			return (-1);
333		}
334		*bp++ = 0;
335	}
336	if ((bp - dst) > MAXCDNAME) {	/*%< src too big */
337		errno = EMSGSIZE;
338		return (-1);
339	}
340	if (dstlen != NULL)
341		*dstlen = (bp - dst);
342	return (0);
343}
344
345/*%
346 *	Convert a network strings labels into all lowercase.
347 *
348 * return:
349 *\li	Number of bytes written to buffer, or -1 (with errno set)
350 *
351 * notes:
352 *\li	Enforces label and domain length limits.
353 */
354
355int
356ns_name_ntol(const u_char *src, u_char *dst, size_t dstsiz)
357{
358	const u_char *cp;
359	u_char *dn, *eom;
360	u_char c;
361	u_int n;
362	int l;
363
364	cp = src;
365	dn = dst;
366	eom = dst + dstsiz;
367
368	if (dn >= eom) {
369		errno = EMSGSIZE;
370		return (-1);
371	}
372	while ((n = *cp++) != 0) {
373		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
374			/* Some kind of compression pointer. */
375			errno = EMSGSIZE;
376			return (-1);
377		}
378		*dn++ = n;
379		if ((l = labellen(cp - 1)) < 0) {
380			errno = EMSGSIZE;
381			return (-1);
382		}
383		if (dn + l >= eom) {
384			errno = EMSGSIZE;
385			return (-1);
386		}
387		for ((void)NULL; l > 0; l--) {
388			c = *cp++;
389			if (isascii(c) && isupper(c))
390				*dn++ = tolower(c);
391			else
392				*dn++ = c;
393		}
394	}
395	*dn++ = '\0';
396	return (dn - dst);
397}
398
399/*%
400 *	Unpack a domain name from a message, source may be compressed.
401 *
402 * return:
403 *\li	-1 if it fails, or consumed octets if it succeeds.
404 */
405int
406ns_name_unpack(const u_char *msg, const u_char *eom, const u_char *src,
407	       u_char *dst, size_t dstsiz)
408{
409	return (ns_name_unpack2(msg, eom, src, dst, dstsiz, NULL));
410}
411
412/*
413 * ns_name_unpack2(msg, eom, src, dst, dstsiz, *dstlen)
414 *	Unpack a domain name from a message, source may be compressed.
415 * return:
416 *	-1 if it fails, or consumed octets if it succeeds.
417 * side effect:
418 *	fills in *dstlen (if non-NULL).
419 */
420int
421ns_name_unpack2(const u_char *msg, const u_char *eom, const u_char *src,
422		u_char *dst, size_t dstsiz, size_t *dstlen)
423{
424	const u_char *srcp, *dstlim;
425	u_char *dstp;
426	int n, len, checked, l;
427
428	len = -1;
429	checked = 0;
430	dstp = dst;
431	srcp = src;
432	dstlim = dst + dstsiz;
433	if (srcp < msg || srcp >= eom) {
434		errno = EMSGSIZE;
435		return (-1);
436	}
437	/* Fetch next label in domain name. */
438	while ((n = *srcp++) != 0) {
439		/* Check for indirection. */
440		switch (n & NS_CMPRSFLGS) {
441		case 0:
442		case NS_TYPE_ELT:
443			/* Limit checks. */
444			if ((l = labellen(srcp - 1)) < 0) {
445				errno = EMSGSIZE;
446				return (-1);
447			}
448			if (dstp + l + 1 >= dstlim || srcp + l >= eom) {
449				errno = EMSGSIZE;
450				return (-1);
451			}
452			checked += l + 1;
453			*dstp++ = n;
454			memcpy(dstp, srcp, l);
455			dstp += l;
456			srcp += l;
457			break;
458
459		case NS_CMPRSFLGS:
460			if (srcp >= eom) {
461				errno = EMSGSIZE;
462				return (-1);
463			}
464			if (len < 0)
465				len = srcp - src + 1;
466
467			n = ((n & 0x3f) << 8) | (*srcp & 0xff);
468			if (n >= eom - msg) {  /*%< Out of range. */
469				errno = EMSGSIZE;
470				return (-1);
471			}
472			srcp = msg + n;
473			checked += 2;
474			/*
475			 * Check for loops in the compressed name;
476			 * if we've looked at the whole message,
477			 * there must be a loop.
478			 */
479			if (checked >= eom - msg) {
480				errno = EMSGSIZE;
481				return (-1);
482			}
483			break;
484
485		default:
486			errno = EMSGSIZE;
487			return (-1);			/*%< flag error */
488		}
489	}
490	*dstp++ = 0;
491	if (dstlen != NULL)
492		*dstlen = dstp - dst;
493	if (len < 0)
494		len = srcp - src;
495	return (len);
496}
497
498/*%
499 *	Pack domain name 'domain' into 'comp_dn'.
500 *
501 * return:
502 *\li	Size of the compressed name, or -1.
503 *
504 * notes:
505 *\li	'dnptrs' is an array of pointers to previous compressed names.
506 *\li	dnptrs[0] is a pointer to the beginning of the message. The array
507 *	ends with NULL.
508 *\li	'lastdnptr' is a pointer to the end of the array pointed to
509 *	by 'dnptrs'.
510 *
511 * Side effects:
512 *\li	The list of pointers in dnptrs is updated for labels inserted into
513 *	the message as we compress the name.  If 'dnptr' is NULL, we don't
514 *	try to compress names. If 'lastdnptr' is NULL, we don't update the
515 *	list.
516 */
517int
518ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
519	     const u_char **dnptrs, const u_char **lastdnptr)
520{
521	u_char *dstp;
522	const u_char **cpp, **lpp, *eob, *msg;
523	const u_char *srcp;
524	int n, l, first = 1;
525
526	srcp = src;
527	dstp = dst;
528	eob = dstp + dstsiz;
529	lpp = cpp = NULL;
530	if (dnptrs != NULL) {
531		if ((msg = *dnptrs++) != NULL) {
532			for (cpp = dnptrs; *cpp != NULL; cpp++)
533				(void)NULL;
534			lpp = cpp;	/*%< end of list to search */
535		}
536	} else
537		msg = NULL;
538
539	/* make sure the domain we are about to add is legal */
540	l = 0;
541	do {
542		int l0;
543
544		n = *srcp;
545		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
546			errno = EMSGSIZE;
547			return (-1);
548		}
549		if ((l0 = labellen(srcp)) < 0) {
550			errno = EINVAL;
551			return (-1);
552		}
553		l += l0 + 1;
554		if (l > MAXCDNAME) {
555			errno = EMSGSIZE;
556			return (-1);
557		}
558		srcp += l0 + 1;
559	} while (n != 0);
560
561	/* from here on we need to reset compression pointer array on error */
562	srcp = src;
563	do {
564		/* Look to see if we can use pointers. */
565		n = *srcp;
566		if (n != 0 && msg != NULL) {
567			l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
568				    (const u_char * const *)lpp);
569			if (l >= 0) {
570				if (dstp + 1 >= eob) {
571					goto cleanup;
572				}
573				*dstp++ = (l >> 8) | NS_CMPRSFLGS;
574				*dstp++ = l % 256;
575				return (dstp - dst);
576			}
577			/* Not found, save it. */
578			if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
579			    (dstp - msg) < 0x4000 && first) {
580				*cpp++ = dstp;
581				*cpp = NULL;
582				first = 0;
583			}
584		}
585		/* copy label to buffer */
586		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
587			/* Should not happen. */
588			goto cleanup;
589		}
590		n = labellen(srcp);
591		if (dstp + 1 + n >= eob) {
592			goto cleanup;
593		}
594		memcpy(dstp, srcp, n + 1);
595		srcp += n + 1;
596		dstp += n + 1;
597	} while (n != 0);
598
599	if (dstp > eob) {
600cleanup:
601		if (msg != NULL)
602			*lpp = NULL;
603		errno = EMSGSIZE;
604		return (-1);
605	}
606	return (dstp - dst);
607}
608
609/*%
610 *	Expand compressed domain name to presentation format.
611 *
612 * return:
613 *\li	Number of bytes read out of `src', or -1 (with errno set).
614 *
615 * note:
616 *\li	Root domain returns as "." not "".
617 */
618int
619ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
620		   char *dst, size_t dstsiz)
621{
622	u_char tmp[NS_MAXCDNAME];
623	int n;
624
625	if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
626		return (-1);
627	if (ns_name_ntop(tmp, dst, dstsiz) == -1)
628		return (-1);
629	return (n);
630}
631
632/*%
633 *	Compress a domain name into wire format, using compression pointers.
634 *
635 * return:
636 *\li	Number of bytes consumed in `dst' or -1 (with errno set).
637 *
638 * notes:
639 *\li	'dnptrs' is an array of pointers to previous compressed names.
640 *\li	dnptrs[0] is a pointer to the beginning of the message.
641 *\li	The list ends with NULL.  'lastdnptr' is a pointer to the end of the
642 *	array pointed to by 'dnptrs'. Side effect is to update the list of
643 *	pointers for labels inserted into the message as we compress the name.
644 *\li	If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
645 *	is NULL, we don't update the list.
646 */
647int
648ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
649		 const u_char **dnptrs, const u_char **lastdnptr)
650{
651	u_char tmp[NS_MAXCDNAME];
652
653	if (ns_name_pton(src, tmp, sizeof tmp) == -1)
654		return (-1);
655	return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
656}
657
658/*%
659 * Reset dnptrs so that there are no active references to pointers at or
660 * after src.
661 */
662void
663ns_name_rollback(const u_char *src, const u_char **dnptrs,
664		 const u_char **lastdnptr)
665{
666	while (dnptrs < lastdnptr && *dnptrs != NULL) {
667		if (*dnptrs >= src) {
668			*dnptrs = NULL;
669			break;
670		}
671		dnptrs++;
672	}
673}
674
675/*%
676 *	Advance *ptrptr to skip over the compressed name it points at.
677 *
678 * return:
679 *\li	0 on success, -1 (with errno set) on failure.
680 */
681int
682ns_name_skip(const u_char **ptrptr, const u_char *eom)
683{
684	const u_char *cp;
685	u_int n;
686	int l;
687
688	cp = *ptrptr;
689	while (cp < eom && (n = *cp++) != 0) {
690		/* Check for indirection. */
691		switch (n & NS_CMPRSFLGS) {
692		case 0:			/*%< normal case, n == len */
693			cp += n;
694			continue;
695		case NS_TYPE_ELT: /*%< EDNS0 extended label */
696			if ((l = labellen(cp - 1)) < 0) {
697				errno = EMSGSIZE; /*%< XXX */
698				return (-1);
699			}
700			cp += l;
701			continue;
702		case NS_CMPRSFLGS:	/*%< indirection */
703			cp++;
704			break;
705		default:		/*%< illegal type */
706			errno = EMSGSIZE;
707			return (-1);
708		}
709		break;
710	}
711	if (cp > eom) {
712		errno = EMSGSIZE;
713		return (-1);
714	}
715	*ptrptr = cp;
716	return (0);
717}
718
719/* Find the number of octets an nname takes up, including the root label.
720 * (This is basically ns_name_skip() without compression-pointer support.)
721 * ((NOTE: can only return zero if passed-in namesiz argument is zero.))
722 */
723ssize_t
724ns_name_length(ns_nname_ct nname, size_t namesiz) {
725	ns_nname_ct orig = nname;
726	u_int n;
727
728	while (namesiz-- > 0 && (n = *nname++) != 0) {
729		if ((n & NS_CMPRSFLGS) != 0) {
730			errno = EISDIR;
731			return (-1);
732		}
733		if (n > namesiz) {
734			errno = EMSGSIZE;
735			return (-1);
736		}
737		nname += n;
738		namesiz -= n;
739	}
740	return (nname - orig);
741}
742
743/* Compare two nname's for equality.  Return -1 on error (setting errno).
744 */
745int
746ns_name_eq(ns_nname_ct a, size_t as, ns_nname_ct b, size_t bs) {
747	ns_nname_ct ae = a + as, be = b + bs;
748	int ac, bc;
749
750	while (ac = *a, bc = *b, ac != 0 && bc != 0) {
751		if ((ac & NS_CMPRSFLGS) != 0 || (bc & NS_CMPRSFLGS) != 0) {
752			errno = EISDIR;
753			return (-1);
754		}
755		if (a + ac >= ae || b + bc >= be) {
756			errno = EMSGSIZE;
757			return (-1);
758		}
759		if (ac != bc || strncasecmp((const char *) ++a,
760					    (const char *) ++b, ac) != 0)
761			return (0);
762		a += ac, b += bc;
763	}
764	return (ac == 0 && bc == 0);
765}
766
767/* Is domain "A" owned by (at or below) domain "B"?
768 */
769int
770ns_name_owned(ns_namemap_ct a, int an, ns_namemap_ct b, int bn) {
771	/* If A is shorter, it cannot be owned by B. */
772	if (an < bn)
773		return (0);
774
775	/* If they are unequal before the length of the shorter, A cannot... */
776	while (bn > 0) {
777		if (a->len != b->len ||
778		    strncasecmp((const char *) a->base,
779				(const char *) b->base, a->len) != 0)
780			return (0);
781		a++, an--;
782		b++, bn--;
783	}
784
785	/* A might be longer or not, but either way, B owns it. */
786	return (1);
787}
788
789/* Build an array of <base,len> tuples from an nname, top-down order.
790 * Return the number of tuples (labels) thus discovered.
791 */
792int
793ns_name_map(ns_nname_ct nname, size_t namelen, ns_namemap_t map, int mapsize) {
794	u_int n;
795	int l;
796
797	n = *nname++;
798	namelen--;
799
800	/* Root zone? */
801	if (n == 0) {
802		/* Extra data follows name? */
803		if (namelen > 0) {
804			errno = EMSGSIZE;
805			return (-1);
806		}
807		return (0);
808	}
809
810	/* Compression pointer? */
811	if ((n & NS_CMPRSFLGS) != 0) {
812		errno = EISDIR;
813		return (-1);
814	}
815
816	/* Label too long? */
817	if (n > namelen) {
818		errno = EMSGSIZE;
819		return (-1);
820	}
821
822	/* Recurse to get rest of name done first. */
823	l = ns_name_map(nname + n, namelen - n, map, mapsize);
824	if (l < 0)
825		return (-1);
826
827	/* Too many labels? */
828	if (l >= mapsize) {
829		errno = ENAMETOOLONG;
830		return (-1);
831	}
832
833	/* We're on our way back up-stack, store current map data. */
834	map[l].base = nname;
835	map[l].len = n;
836	return (l + 1);
837}
838
839/* Count the labels in a domain name.  Root counts, so COM. has two.  This
840 * is to make the result comparable to the result of ns_name_map().
841 */
842int
843ns_name_labels(ns_nname_ct nname, size_t namesiz) {
844	int ret = 0;
845	u_int n;
846
847	while (namesiz-- > 0 && (n = *nname++) != 0) {
848		if ((n & NS_CMPRSFLGS) != 0) {
849			errno = EISDIR;
850			return (-1);
851		}
852		if (n > namesiz) {
853			errno = EMSGSIZE;
854			return (-1);
855		}
856		nname += n;
857		namesiz -= n;
858		ret++;
859	}
860	return (ret + 1);
861}
862
863/* Private. */
864
865/*%
866 *	Thinking in noninternationalized USASCII (per the DNS spec),
867 *	is this characted special ("in need of quoting") ?
868 *
869 * return:
870 *\li	boolean.
871 */
872static int
873special(int ch) {
874	switch (ch) {
875	case 0x22: /*%< '"' */
876	case 0x2E: /*%< '.' */
877	case 0x3B: /*%< ';' */
878	case 0x5C: /*%< '\\' */
879	case 0x28: /*%< '(' */
880	case 0x29: /*%< ')' */
881	/* Special modifiers in zone files. */
882	case 0x40: /*%< '@' */
883	case 0x24: /*%< '$' */
884		return (1);
885	default:
886		return (0);
887	}
888}
889
890/*%
891 *	Thinking in noninternationalized USASCII (per the DNS spec),
892 *	is this character visible and not a space when printed ?
893 *
894 * return:
895 *\li	boolean.
896 */
897static int
898printable(int ch) {
899	return (ch > 0x20 && ch < 0x7f);
900}
901
902/*%
903 *	Thinking in noninternationalized USASCII (per the DNS spec),
904 *	convert this character to lower case if it's upper case.
905 */
906static int
907mklower(int ch) {
908	if (ch >= 0x41 && ch <= 0x5A)
909		return (ch + 0x20);
910	return (ch);
911}
912
913/*%
914 *	Search for the counted-label name in an array of compressed names.
915 *
916 * return:
917 *\li	offset from msg if found, or -1.
918 *
919 * notes:
920 *\li	dnptrs is the pointer to the first name on the list,
921 *\li	not the pointer to the start of the message.
922 */
923static int
924dn_find(const u_char *domain, const u_char *msg,
925	const u_char * const *dnptrs,
926	const u_char * const *lastdnptr)
927{
928	const u_char *dn, *cp, *sp;
929	const u_char * const *cpp;
930	u_int n;
931
932	for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
933		sp = *cpp;
934		/*
935		 * terminate search on:
936		 * root label
937		 * compression pointer
938		 * unusable offset
939		 */
940		while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
941		       (sp - msg) < 0x4000) {
942			dn = domain;
943			cp = sp;
944			while ((n = *cp++) != 0) {
945				/*
946				 * check for indirection
947				 */
948				switch (n & NS_CMPRSFLGS) {
949				case 0:		/*%< normal case, n == len */
950					n = labellen(cp - 1); /*%< XXX */
951					if (n != *dn++)
952						goto next;
953
954					for ((void)NULL; n > 0; n--)
955						if (mklower(*dn++) !=
956						    mklower(*cp++))
957							goto next;
958					/* Is next root for both ? */
959					if (*dn == '\0' && *cp == '\0')
960						return (sp - msg);
961					if (*dn)
962						continue;
963					goto next;
964				case NS_CMPRSFLGS:	/*%< indirection */
965					cp = msg + (((n & 0x3f) << 8) | *cp);
966					break;
967
968				default:	/*%< illegal type */
969					errno = EMSGSIZE;
970					return (-1);
971				}
972			}
973 next: ;
974			sp += *sp + 1;
975		}
976	}
977	errno = ENOENT;
978	return (-1);
979}
980
981static int
982decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
983{
984	const unsigned char *cp = *cpp;
985	char *beg = dn, tc;
986	int b, blen, plen, i;
987
988	if ((blen = (*cp & 0xff)) == 0)
989		blen = 256;
990	plen = (blen + 3) / 4;
991	plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
992	if (dn + plen >= eom)
993		return (-1);
994
995	cp++;
996	i = SPRINTF((dn, "\\[x"));
997	if (i < 0)
998		return (-1);
999	dn += i;
1000	for (b = blen; b > 7; b -= 8, cp++) {
1001		i = SPRINTF((dn, "%02x", *cp & 0xff));
1002		if (i < 0)
1003			return (-1);
1004		dn += i;
1005	}
1006	if (b > 4) {
1007		tc = *cp++;
1008		i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
1009		if (i < 0)
1010			return (-1);
1011		dn += i;
1012	} else if (b > 0) {
1013		tc = *cp++;
1014		i = SPRINTF((dn, "%1x",
1015			       ((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
1016		if (i < 0)
1017			return (-1);
1018		dn += i;
1019	}
1020	i = SPRINTF((dn, "/%d]", blen));
1021	if (i < 0)
1022		return (-1);
1023	dn += i;
1024
1025	*cpp = cp;
1026	return (dn - beg);
1027}
1028
1029static int
1030encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
1031		unsigned char ** dst, unsigned const char *eom)
1032{
1033	int afterslash = 0;
1034	const char *cp = *bp;
1035	unsigned char *tp;
1036	char c;
1037	const char *beg_blen;
1038	char *end_blen = NULL;
1039	int value = 0, count = 0, tbcount = 0, blen = 0;
1040
1041	beg_blen = end_blen = NULL;
1042
1043	/* a bitstring must contain at least 2 characters */
1044	if (end - cp < 2)
1045		return (EINVAL);
1046
1047	/* XXX: currently, only hex strings are supported */
1048	if (*cp++ != 'x')
1049		return (EINVAL);
1050	if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
1051		return (EINVAL);
1052
1053	for (tp = *dst + 1; cp < end && tp < eom; cp++) {
1054		switch((c = *cp)) {
1055		case ']':	/*%< end of the bitstring */
1056			if (afterslash) {
1057				if (beg_blen == NULL)
1058					return (EINVAL);
1059				blen = (int)strtol(beg_blen, &end_blen, 10);
1060				if (*end_blen != ']')
1061					return (EINVAL);
1062			}
1063			if (count)
1064				*tp++ = ((value << 4) & 0xff);
1065			cp++;	/*%< skip ']' */
1066			goto done;
1067		case '/':
1068			afterslash = 1;
1069			break;
1070		default:
1071			if (afterslash) {
1072				if (!isdigit(c&0xff))
1073					return (EINVAL);
1074				if (beg_blen == NULL) {
1075
1076					if (c == '0') {
1077						/* blen never begings with 0 */
1078						return (EINVAL);
1079					}
1080					beg_blen = cp;
1081				}
1082			} else {
1083				if (!isxdigit(c&0xff))
1084					return (EINVAL);
1085				value <<= 4;
1086				value += digitvalue[(int)c];
1087				count += 4;
1088				tbcount += 4;
1089				if (tbcount > 256)
1090					return (EINVAL);
1091				if (count == 8) {
1092					*tp++ = value;
1093					count = 0;
1094				}
1095			}
1096			break;
1097		}
1098	}
1099  done:
1100	if (cp >= end || tp >= eom)
1101		return (EMSGSIZE);
1102
1103	/*
1104	 * bit length validation:
1105	 * If a <length> is present, the number of digits in the <bit-data>
1106	 * MUST be just sufficient to contain the number of bits specified
1107	 * by the <length>. If there are insignificant bits in a final
1108	 * hexadecimal or octal digit, they MUST be zero.
1109	 * RFC2673, Section 3.2.
1110	 */
1111	if (blen > 0) {
1112		int traillen;
1113
1114		if (((blen + 3) & ~3) != tbcount)
1115			return (EINVAL);
1116		traillen = tbcount - blen; /*%< between 0 and 3 */
1117		if (((value << (8 - traillen)) & 0xff) != 0)
1118			return (EINVAL);
1119	}
1120	else
1121		blen = tbcount;
1122	if (blen == 256)
1123		blen = 0;
1124
1125	/* encode the type and the significant bit fields */
1126	**labelp = DNS_LABELTYPE_BITSTRING;
1127	**dst = blen;
1128
1129	*bp = cp;
1130	*dst = tp;
1131
1132	return (0);
1133}
1134
1135static int
1136labellen(const u_char *lp)
1137{
1138	int bitlen;
1139	u_char l = *lp;
1140
1141	if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
1142		/* should be avoided by the caller */
1143		return (-1);
1144	}
1145
1146	if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
1147		if (l == DNS_LABELTYPE_BITSTRING) {
1148			if ((bitlen = *(lp + 1)) == 0)
1149				bitlen = 256;
1150			return ((bitlen + 7 ) / 8 + 1);
1151		}
1152		return (-1);	/*%< unknwon ELT */
1153	}
1154	return (l);
1155}
1156
1157/*! \file */
1158