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#ifndef lint
19static const char rcsid[] = "$Id: ns_name.c,v 1.11 2009/01/23 19:59:16 each Exp $";
20#endif
21#include <sys/cdefs.h>
22__FBSDID("$FreeBSD$");
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			l = ((n & 0x3f) << 8) | (*srcp & 0xff);
467			if (l >= eom - msg) {  /*%< Out of range. */
468				errno = EMSGSIZE;
469				return (-1);
470			}
471			srcp = msg + l;
472			checked += 2;
473			/*
474			 * Check for loops in the compressed name;
475			 * if we've looked at the whole message,
476			 * there must be a loop.
477			 */
478			if (checked >= eom - msg) {
479				errno = EMSGSIZE;
480				return (-1);
481			}
482			break;
483
484		default:
485			errno = EMSGSIZE;
486			return (-1);			/*%< flag error */
487		}
488	}
489	*dstp++ = 0;
490	if (dstlen != NULL)
491		*dstlen = dstp - dst;
492	if (len < 0)
493		len = srcp - src;
494	return (len);
495}
496
497/*%
498 *	Pack domain name 'domain' into 'comp_dn'.
499 *
500 * return:
501 *\li	Size of the compressed name, or -1.
502 *
503 * notes:
504 *\li	'dnptrs' is an array of pointers to previous compressed names.
505 *\li	dnptrs[0] is a pointer to the beginning of the message. The array
506 *	ends with NULL.
507 *\li	'lastdnptr' is a pointer to the end of the array pointed to
508 *	by 'dnptrs'.
509 *
510 * Side effects:
511 *\li	The list of pointers in dnptrs is updated for labels inserted into
512 *	the message as we compress the name.  If 'dnptr' is NULL, we don't
513 *	try to compress names. If 'lastdnptr' is NULL, we don't update the
514 *	list.
515 */
516int
517ns_name_pack(const u_char *src, u_char *dst, int dstsiz,
518	     const u_char **dnptrs, const u_char **lastdnptr)
519{
520	u_char *dstp;
521	const u_char **cpp, **lpp, *eob, *msg;
522	const u_char *srcp;
523	int n, l, first = 1;
524
525	srcp = src;
526	dstp = dst;
527	eob = dstp + dstsiz;
528	lpp = cpp = NULL;
529	if (dnptrs != NULL) {
530		if ((msg = *dnptrs++) != NULL) {
531			for (cpp = dnptrs; *cpp != NULL; cpp++)
532				(void)NULL;
533			lpp = cpp;	/*%< end of list to search */
534		}
535	} else
536		msg = NULL;
537
538	/* make sure the domain we are about to add is legal */
539	l = 0;
540	do {
541		int l0;
542
543		n = *srcp;
544		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
545			errno = EMSGSIZE;
546			return (-1);
547		}
548		if ((l0 = labellen(srcp)) < 0) {
549			errno = EINVAL;
550			return (-1);
551		}
552		l += l0 + 1;
553		if (l > MAXCDNAME) {
554			errno = EMSGSIZE;
555			return (-1);
556		}
557		srcp += l0 + 1;
558	} while (n != 0);
559
560	/* from here on we need to reset compression pointer array on error */
561	srcp = src;
562	do {
563		/* Look to see if we can use pointers. */
564		n = *srcp;
565		if (n != 0 && msg != NULL) {
566			l = dn_find(srcp, msg, (const u_char * const *)dnptrs,
567				    (const u_char * const *)lpp);
568			if (l >= 0) {
569				if (dstp + 1 >= eob) {
570					goto cleanup;
571				}
572				*dstp++ = (l >> 8) | NS_CMPRSFLGS;
573				*dstp++ = l % 256;
574				return (dstp - dst);
575			}
576			/* Not found, save it. */
577			if (lastdnptr != NULL && cpp < lastdnptr - 1 &&
578			    (dstp - msg) < 0x4000 && first) {
579				*cpp++ = dstp;
580				*cpp = NULL;
581				first = 0;
582			}
583		}
584		/* copy label to buffer */
585		if ((n & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
586			/* Should not happen. */
587			goto cleanup;
588		}
589		n = labellen(srcp);
590		if (dstp + 1 + n >= eob) {
591			goto cleanup;
592		}
593		memcpy(dstp, srcp, n + 1);
594		srcp += n + 1;
595		dstp += n + 1;
596	} while (n != 0);
597
598	if (dstp > eob) {
599cleanup:
600		if (msg != NULL)
601			*lpp = NULL;
602		errno = EMSGSIZE;
603		return (-1);
604	}
605	return (dstp - dst);
606}
607
608/*%
609 *	Expand compressed domain name to presentation format.
610 *
611 * return:
612 *\li	Number of bytes read out of `src', or -1 (with errno set).
613 *
614 * note:
615 *\li	Root domain returns as "." not "".
616 */
617int
618ns_name_uncompress(const u_char *msg, const u_char *eom, const u_char *src,
619		   char *dst, size_t dstsiz)
620{
621	u_char tmp[NS_MAXCDNAME];
622	int n;
623
624	if ((n = ns_name_unpack(msg, eom, src, tmp, sizeof tmp)) == -1)
625		return (-1);
626	if (ns_name_ntop(tmp, dst, dstsiz) == -1)
627		return (-1);
628	return (n);
629}
630
631/*%
632 *	Compress a domain name into wire format, using compression pointers.
633 *
634 * return:
635 *\li	Number of bytes consumed in `dst' or -1 (with errno set).
636 *
637 * notes:
638 *\li	'dnptrs' is an array of pointers to previous compressed names.
639 *\li	dnptrs[0] is a pointer to the beginning of the message.
640 *\li	The list ends with NULL.  'lastdnptr' is a pointer to the end of the
641 *	array pointed to by 'dnptrs'. Side effect is to update the list of
642 *	pointers for labels inserted into the message as we compress the name.
643 *\li	If 'dnptr' is NULL, we don't try to compress names. If 'lastdnptr'
644 *	is NULL, we don't update the list.
645 */
646int
647ns_name_compress(const char *src, u_char *dst, size_t dstsiz,
648		 const u_char **dnptrs, const u_char **lastdnptr)
649{
650	u_char tmp[NS_MAXCDNAME];
651
652	if (ns_name_pton(src, tmp, sizeof tmp) == -1)
653		return (-1);
654	return (ns_name_pack(tmp, dst, dstsiz, dnptrs, lastdnptr));
655}
656
657/*%
658 * Reset dnptrs so that there are no active references to pointers at or
659 * after src.
660 */
661void
662ns_name_rollback(const u_char *src, const u_char **dnptrs,
663		 const u_char **lastdnptr)
664{
665	while (dnptrs < lastdnptr && *dnptrs != NULL) {
666		if (*dnptrs >= src) {
667			*dnptrs = NULL;
668			break;
669		}
670		dnptrs++;
671	}
672}
673
674/*%
675 *	Advance *ptrptr to skip over the compressed name it points at.
676 *
677 * return:
678 *\li	0 on success, -1 (with errno set) on failure.
679 */
680int
681ns_name_skip(const u_char **ptrptr, const u_char *eom)
682{
683	const u_char *cp;
684	u_int n;
685	int l;
686
687	cp = *ptrptr;
688	while (cp < eom && (n = *cp++) != 0) {
689		/* Check for indirection. */
690		switch (n & NS_CMPRSFLGS) {
691		case 0:			/*%< normal case, n == len */
692			cp += n;
693			continue;
694		case NS_TYPE_ELT: /*%< EDNS0 extended label */
695			if ((l = labellen(cp - 1)) < 0) {
696				errno = EMSGSIZE; /*%< XXX */
697				return (-1);
698			}
699			cp += l;
700			continue;
701		case NS_CMPRSFLGS:	/*%< indirection */
702			cp++;
703			break;
704		default:		/*%< illegal type */
705			errno = EMSGSIZE;
706			return (-1);
707		}
708		break;
709	}
710	if (cp > eom) {
711		errno = EMSGSIZE;
712		return (-1);
713	}
714	*ptrptr = cp;
715	return (0);
716}
717
718/* Find the number of octets an nname takes up, including the root label.
719 * (This is basically ns_name_skip() without compression-pointer support.)
720 * ((NOTE: can only return zero if passed-in namesiz argument is zero.))
721 */
722ssize_t
723ns_name_length(ns_nname_ct nname, size_t namesiz) {
724	ns_nname_ct orig = nname;
725	u_int n;
726
727	while (namesiz-- > 0 && (n = *nname++) != 0) {
728		if ((n & NS_CMPRSFLGS) != 0) {
729			errno = EISDIR;
730			return (-1);
731		}
732		if (n > namesiz) {
733			errno = EMSGSIZE;
734			return (-1);
735		}
736		nname += n;
737		namesiz -= n;
738	}
739	return (nname - orig);
740}
741
742/* Compare two nname's for equality.  Return -1 on error (setting errno).
743 */
744int
745ns_name_eq(ns_nname_ct a, size_t as, ns_nname_ct b, size_t bs) {
746	ns_nname_ct ae = a + as, be = b + bs;
747	int ac, bc;
748
749	while (ac = *a, bc = *b, ac != 0 && bc != 0) {
750		if ((ac & NS_CMPRSFLGS) != 0 || (bc & NS_CMPRSFLGS) != 0) {
751			errno = EISDIR;
752			return (-1);
753		}
754		if (a + ac >= ae || b + bc >= be) {
755			errno = EMSGSIZE;
756			return (-1);
757		}
758		if (ac != bc || strncasecmp((const char *) ++a,
759					    (const char *) ++b, ac) != 0)
760			return (0);
761		a += ac, b += bc;
762	}
763	return (ac == 0 && bc == 0);
764}
765
766/* Is domain "A" owned by (at or below) domain "B"?
767 */
768int
769ns_name_owned(ns_namemap_ct a, int an, ns_namemap_ct b, int bn) {
770	/* If A is shorter, it cannot be owned by B. */
771	if (an < bn)
772		return (0);
773
774	/* If they are unequal before the length of the shorter, A cannot... */
775	while (bn > 0) {
776		if (a->len != b->len ||
777		    strncasecmp((const char *) a->base,
778				(const char *) b->base, a->len) != 0)
779			return (0);
780		a++, an--;
781		b++, bn--;
782	}
783
784	/* A might be longer or not, but either way, B owns it. */
785	return (1);
786}
787
788/* Build an array of <base,len> tuples from an nname, top-down order.
789 * Return the number of tuples (labels) thus discovered.
790 */
791int
792ns_name_map(ns_nname_ct nname, size_t namelen, ns_namemap_t map, int mapsize) {
793	u_int n;
794	int l;
795
796	n = *nname++;
797	namelen--;
798
799	/* Root zone? */
800	if (n == 0) {
801		/* Extra data follows name? */
802		if (namelen > 0) {
803			errno = EMSGSIZE;
804			return (-1);
805		}
806		return (0);
807	}
808
809	/* Compression pointer? */
810	if ((n & NS_CMPRSFLGS) != 0) {
811		errno = EISDIR;
812		return (-1);
813	}
814
815	/* Label too long? */
816	if (n > namelen) {
817		errno = EMSGSIZE;
818		return (-1);
819	}
820
821	/* Recurse to get rest of name done first. */
822	l = ns_name_map(nname + n, namelen - n, map, mapsize);
823	if (l < 0)
824		return (-1);
825
826	/* Too many labels? */
827	if (l >= mapsize) {
828		errno = ENAMETOOLONG;
829		return (-1);
830	}
831
832	/* We're on our way back up-stack, store current map data. */
833	map[l].base = nname;
834	map[l].len = n;
835	return (l + 1);
836}
837
838/* Count the labels in a domain name.  Root counts, so COM. has two.  This
839 * is to make the result comparable to the result of ns_name_map().
840 */
841int
842ns_name_labels(ns_nname_ct nname, size_t namesiz) {
843	int ret = 0;
844	u_int n;
845
846	while (namesiz-- > 0 && (n = *nname++) != 0) {
847		if ((n & NS_CMPRSFLGS) != 0) {
848			errno = EISDIR;
849			return (-1);
850		}
851		if (n > namesiz) {
852			errno = EMSGSIZE;
853			return (-1);
854		}
855		nname += n;
856		namesiz -= n;
857		ret++;
858	}
859	return (ret + 1);
860}
861
862/* Private. */
863
864/*%
865 *	Thinking in noninternationalized USASCII (per the DNS spec),
866 *	is this characted special ("in need of quoting") ?
867 *
868 * return:
869 *\li	boolean.
870 */
871static int
872special(int ch) {
873	switch (ch) {
874	case 0x22: /*%< '"' */
875	case 0x2E: /*%< '.' */
876	case 0x3B: /*%< ';' */
877	case 0x5C: /*%< '\\' */
878	case 0x28: /*%< '(' */
879	case 0x29: /*%< ')' */
880	/* Special modifiers in zone files. */
881	case 0x40: /*%< '@' */
882	case 0x24: /*%< '$' */
883		return (1);
884	default:
885		return (0);
886	}
887}
888
889/*%
890 *	Thinking in noninternationalized USASCII (per the DNS spec),
891 *	is this character visible and not a space when printed ?
892 *
893 * return:
894 *\li	boolean.
895 */
896static int
897printable(int ch) {
898	return (ch > 0x20 && ch < 0x7f);
899}
900
901/*%
902 *	Thinking in noninternationalized USASCII (per the DNS spec),
903 *	convert this character to lower case if it's upper case.
904 */
905static int
906mklower(int ch) {
907	if (ch >= 0x41 && ch <= 0x5A)
908		return (ch + 0x20);
909	return (ch);
910}
911
912/*%
913 *	Search for the counted-label name in an array of compressed names.
914 *
915 * return:
916 *\li	offset from msg if found, or -1.
917 *
918 * notes:
919 *\li	dnptrs is the pointer to the first name on the list,
920 *\li	not the pointer to the start of the message.
921 */
922static int
923dn_find(const u_char *domain, const u_char *msg,
924	const u_char * const *dnptrs,
925	const u_char * const *lastdnptr)
926{
927	const u_char *dn, *cp, *sp;
928	const u_char * const *cpp;
929	u_int n;
930
931	for (cpp = dnptrs; cpp < lastdnptr; cpp++) {
932		sp = *cpp;
933		/*
934		 * terminate search on:
935		 * root label
936		 * compression pointer
937		 * unusable offset
938		 */
939		while (*sp != 0 && (*sp & NS_CMPRSFLGS) == 0 &&
940		       (sp - msg) < 0x4000) {
941			dn = domain;
942			cp = sp;
943			while ((n = *cp++) != 0) {
944				/*
945				 * check for indirection
946				 */
947				switch (n & NS_CMPRSFLGS) {
948				case 0:		/*%< normal case, n == len */
949					n = labellen(cp - 1); /*%< XXX */
950					if (n != *dn++)
951						goto next;
952
953					for ((void)NULL; n > 0; n--)
954						if (mklower(*dn++) !=
955						    mklower(*cp++))
956							goto next;
957					/* Is next root for both ? */
958					if (*dn == '\0' && *cp == '\0')
959						return (sp - msg);
960					if (*dn)
961						continue;
962					goto next;
963				case NS_CMPRSFLGS:	/*%< indirection */
964					cp = msg + (((n & 0x3f) << 8) | *cp);
965					break;
966
967				default:	/*%< illegal type */
968					errno = EMSGSIZE;
969					return (-1);
970				}
971			}
972 next: ;
973			sp += *sp + 1;
974		}
975	}
976	errno = ENOENT;
977	return (-1);
978}
979
980static int
981decode_bitstring(const unsigned char **cpp, char *dn, const char *eom)
982{
983	const unsigned char *cp = *cpp;
984	char *beg = dn, tc;
985	int b, blen, plen, i;
986
987	if ((blen = (*cp & 0xff)) == 0)
988		blen = 256;
989	plen = (blen + 3) / 4;
990	plen += sizeof("\\[x/]") + (blen > 99 ? 3 : (blen > 9) ? 2 : 1);
991	if (dn + plen >= eom)
992		return (-1);
993
994	cp++;
995	i = SPRINTF((dn, "\\[x"));
996	if (i < 0)
997		return (-1);
998	dn += i;
999	for (b = blen; b > 7; b -= 8, cp++) {
1000		i = SPRINTF((dn, "%02x", *cp & 0xff));
1001		if (i < 0)
1002			return (-1);
1003		dn += i;
1004	}
1005	if (b > 4) {
1006		tc = *cp++;
1007		i = SPRINTF((dn, "%02x", tc & (0xff << (8 - b))));
1008		if (i < 0)
1009			return (-1);
1010		dn += i;
1011	} else if (b > 0) {
1012		tc = *cp++;
1013		i = SPRINTF((dn, "%1x",
1014			       ((tc >> 4) & 0x0f) & (0x0f << (4 - b))));
1015		if (i < 0)
1016			return (-1);
1017		dn += i;
1018	}
1019	i = SPRINTF((dn, "/%d]", blen));
1020	if (i < 0)
1021		return (-1);
1022	dn += i;
1023
1024	*cpp = cp;
1025	return (dn - beg);
1026}
1027
1028static int
1029encode_bitsring(const char **bp, const char *end, unsigned char **labelp,
1030		unsigned char ** dst, unsigned const char *eom)
1031{
1032	int afterslash = 0;
1033	const char *cp = *bp;
1034	unsigned char *tp;
1035	char c;
1036	const char *beg_blen;
1037	char *end_blen = NULL;
1038	int value = 0, count = 0, tbcount = 0, blen = 0;
1039
1040	beg_blen = end_blen = NULL;
1041
1042	/* a bitstring must contain at least 2 characters */
1043	if (end - cp < 2)
1044		return (EINVAL);
1045
1046	/* XXX: currently, only hex strings are supported */
1047	if (*cp++ != 'x')
1048		return (EINVAL);
1049	if (!isxdigit((*cp) & 0xff)) /*%< reject '\[x/BLEN]' */
1050		return (EINVAL);
1051
1052	for (tp = *dst + 1; cp < end && tp < eom; cp++) {
1053		switch((c = *cp)) {
1054		case ']':	/*%< end of the bitstring */
1055			if (afterslash) {
1056				if (beg_blen == NULL)
1057					return (EINVAL);
1058				blen = (int)strtol(beg_blen, &end_blen, 10);
1059				if (*end_blen != ']')
1060					return (EINVAL);
1061			}
1062			if (count)
1063				*tp++ = ((value << 4) & 0xff);
1064			cp++;	/*%< skip ']' */
1065			goto done;
1066		case '/':
1067			afterslash = 1;
1068			break;
1069		default:
1070			if (afterslash) {
1071				if (!isdigit(c&0xff))
1072					return (EINVAL);
1073				if (beg_blen == NULL) {
1074
1075					if (c == '0') {
1076						/* blen never begings with 0 */
1077						return (EINVAL);
1078					}
1079					beg_blen = cp;
1080				}
1081			} else {
1082				if (!isxdigit(c&0xff))
1083					return (EINVAL);
1084				value <<= 4;
1085				value += digitvalue[(int)c];
1086				count += 4;
1087				tbcount += 4;
1088				if (tbcount > 256)
1089					return (EINVAL);
1090				if (count == 8) {
1091					*tp++ = value;
1092					count = 0;
1093				}
1094			}
1095			break;
1096		}
1097	}
1098  done:
1099	if (cp >= end || tp >= eom)
1100		return (EMSGSIZE);
1101
1102	/*
1103	 * bit length validation:
1104	 * If a <length> is present, the number of digits in the <bit-data>
1105	 * MUST be just sufficient to contain the number of bits specified
1106	 * by the <length>. If there are insignificant bits in a final
1107	 * hexadecimal or octal digit, they MUST be zero.
1108	 * RFC2673, Section 3.2.
1109	 */
1110	if (blen > 0) {
1111		int traillen;
1112
1113		if (((blen + 3) & ~3) != tbcount)
1114			return (EINVAL);
1115		traillen = tbcount - blen; /*%< between 0 and 3 */
1116		if (((value << (8 - traillen)) & 0xff) != 0)
1117			return (EINVAL);
1118	}
1119	else
1120		blen = tbcount;
1121	if (blen == 256)
1122		blen = 0;
1123
1124	/* encode the type and the significant bit fields */
1125	**labelp = DNS_LABELTYPE_BITSTRING;
1126	**dst = blen;
1127
1128	*bp = cp;
1129	*dst = tp;
1130
1131	return (0);
1132}
1133
1134static int
1135labellen(const u_char *lp)
1136{
1137	int bitlen;
1138	u_char l = *lp;
1139
1140	if ((l & NS_CMPRSFLGS) == NS_CMPRSFLGS) {
1141		/* should be avoided by the caller */
1142		return (-1);
1143	}
1144
1145	if ((l & NS_CMPRSFLGS) == NS_TYPE_ELT) {
1146		if (l == DNS_LABELTYPE_BITSTRING) {
1147			if ((bitlen = *(lp + 1)) == 0)
1148				bitlen = 256;
1149			return ((bitlen + 7 ) / 8 + 1);
1150		}
1151		return (-1);	/*%< unknwon ELT */
1152	}
1153	return (l);
1154}
1155
1156/*! \file */
1157