1#ifndef __APPLE__
2#if !defined(lint) && !defined(SABER)
3static const char rcsid[] = "$Id: res_findzonecut.c,v 1.1 2006/03/01 19:01:38 majka Exp $";
4#endif /* not lint */
5#endif
6
7/*
8 * Copyright (c) 1999 by Internet Software Consortium.
9 *
10 * Permission to use, copy, modify, and distribute this software for any
11 * purpose with or without fee is hereby granted, provided that the above
12 * copyright notice and this permission notice appear in all copies.
13 *
14 * THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM DISCLAIMS
15 * ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
16 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
17 * CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
18 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
19 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
20 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
21 * SOFTWARE.
22 */
23
24/* Import. */
25
26#ifndef __APPLE__
27#include "port_before.h"
28#endif
29
30#include <sys/param.h>
31#include <sys/socket.h>
32#include <sys/time.h>
33
34#include <netinet/in.h>
35#include <arpa/inet.h>
36#include <arpa/nameser.h>
37
38#include <errno.h>
39#include <limits.h>
40#include <netdb.h>
41#include <stdarg.h>
42#include <stdio.h>
43#include <stdlib.h>
44#include <string.h>
45
46#ifndef __APPLE__
47#include <isc/list.h>
48#include "port_after.h"
49#else
50#include <res_update.h>
51#endif
52
53#include <resolv.h>
54
55/* Data structures. */
56
57typedef struct rr_a {
58	LINK(struct rr_a)	link;
59	union res_sockaddr_union		addr;
60} rr_a;
61typedef LIST(rr_a) rrset_a;
62
63typedef struct rr_ns {
64	LINK(struct rr_ns)	link;
65	const char *		name;
66	int			have_v4;
67	int			have_v6;
68	rrset_a			addrs;
69} rr_ns;
70typedef LIST(rr_ns) rrset_ns;
71
72/* Forward. */
73
74static int	satisfy(res_state, const char *, rrset_ns *,
75			union res_sockaddr_union *, int);
76static int	add_addrs(res_state, rr_ns *,
77			  union res_sockaddr_union *, int);
78static int	get_soa(res_state, const char *, ns_class, int,
79			char *, size_t, char *, size_t,
80			rrset_ns *);
81static int	get_ns(res_state, const char *, ns_class, int, rrset_ns *);
82static int	get_glue(res_state, ns_class, int, rrset_ns *);
83static int	save_ns(res_state, ns_msg *, ns_sect,
84			const char *, ns_class, int, rrset_ns *);
85static int	save_a(res_state, ns_msg *, ns_sect,
86		       const char *, ns_class, int, rr_ns *);
87static void	free_nsrrset(rrset_ns *);
88static void	free_nsrr(rrset_ns *, rr_ns *);
89static rr_ns *	find_ns(rrset_ns *, const char *);
90static int	do_query(res_state, const char *, ns_class, ns_type,
91			 u_char *, ns_msg *);
92#ifndef __APPLE__
93static void	res_dprintf(const char *, ...) ISC_FORMAT_PRINTF(1, 2);
94#else
95static void	res_dprintf(const char *, ...);
96#endif
97
98/* Macros. */
99
100#define DPRINTF(x) do {\
101		int save_errno = errno; \
102		if ((statp->options & RES_DEBUG) != 0) res_dprintf x; \
103		errno = save_errno; \
104	} while (0)
105
106/* Public. */
107
108/*
109 * int
110 * res_findzonecut(res, dname, class, zname, zsize, addrs, naddrs)
111 *	find enclosing zone for a <dname,class>, and some server addresses
112 * parameters:
113 *	res - resolver context to work within (is modified)
114 *	dname - domain name whose enclosing zone is desired
115 *	class - class of dname (and its enclosing zone)
116 *	zname - found zone name
117 *	zsize - allocated size of zname
118 *	addrs - found server addresses
119 *	naddrs - max number of addrs
120 * return values:
121 *	< 0 - an error occurred (check errno)
122 *	= 0 - zname is now valid, but addrs[] wasn't changed
123 *	> 0 - zname is now valid, and return value is number of addrs[] found
124 * notes:
125 *	this function calls res_nsend() which means it depends on correctly
126 *	functioning recursive nameservers (usually defined in /etc/resolv.conf
127 *	or its local equivilent).
128 *
129 *	we start by asking for an SOA<dname,class>.  if we get one as an
130 *	answer, that just means <dname,class> is a zone top, which is fine.
131 *	more than likely we'll be told to go pound sand, in the form of a
132 *	negative answer.
133 *
134 *	note that we are not prepared to deal with referrals since that would
135 *	only come from authority servers and our correctly functioning local
136 *	recursive server would have followed the referral and got us something
137 *	more definite.
138 *
139 *	if the authority section contains an SOA, this SOA should also be the
140 *	closest enclosing zone, since any intermediary zone cuts would've been
141 *	returned as referrals and dealt with by our correctly functioning local
142 *	recursive name server.  but an SOA in the authority section should NOT
143 *	match our dname (since that would have been returned in the answer
144 *	section).  an authority section SOA has to be "above" our dname.
145 *
146 *	however, since authority section SOA's were once optional, it's
147 *	possible that we'll have to go hunting for the enclosing SOA by
148 *	ripping labels off the front of our dname -- this is known as "doing
149 *	it the hard way."
150 *
151 *	ultimately we want some server addresses, which are ideally the ones
152 *	pertaining to the SOA.MNAME, but only if there is a matching NS RR.
153 *	so the second phase (after we find an SOA) is to go looking for the
154 *	NS RRset for that SOA's zone.
155 *
156 *	no answer section processed by this code is allowed to contain CNAME
157 *	or DNAME RR's.  for the SOA query this means we strip a label and
158 *	keep going.  for the NS and A queries this means we just give up.
159 */
160
161int
162res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
163		char *zname, size_t zsize, struct in_addr *addrs, int naddrs) {
164	int result, i;
165	union res_sockaddr_union *u;
166
167
168	opts |= RES_IPV4ONLY;
169	opts &= ~RES_IPV6ONLY;
170
171	u = calloc(naddrs, sizeof(*u));
172	if (u == NULL)
173		return(-1);
174
175	result = res_findzonecut2(statp, dname, class, opts, zname, zsize,
176				  u, naddrs);
177
178	for (i = 0; i < result; i++) {
179		addrs[i] = u[i].sin.sin_addr;
180	}
181	free(u);
182	return (result);
183}
184
185int
186res_findzonecut2(res_state statp, const char *dname, ns_class class, int opts,
187		 char *zname, size_t zsize, union res_sockaddr_union *addrs,
188		 int naddrs)
189{
190	char mname[NS_MAXDNAME];
191	u_long save_pfcode;
192	rrset_ns nsrrs;
193	int n;
194
195	DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
196		 dname, p_class(class), (long)zsize, naddrs));
197	save_pfcode = statp->pfcode;
198	statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
199			 RES_PRF_QUES | RES_PRF_ANS |
200			 RES_PRF_AUTH | RES_PRF_ADD;
201	INIT_LIST(nsrrs);
202
203	DPRINTF(("get the soa, and see if it has enough glue"));
204	if ((n = get_soa(statp, dname, class, opts, zname, zsize,
205			 mname, sizeof mname, &nsrrs)) < 0 ||
206	    ((opts & RES_EXHAUSTIVE) == 0 &&
207	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
208		goto done;
209
210	DPRINTF(("get the ns rrset and see if it has enough glue"));
211	if ((n = get_ns(statp, zname, class, opts, &nsrrs)) < 0 ||
212	    ((opts & RES_EXHAUSTIVE) == 0 &&
213	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
214		goto done;
215
216	DPRINTF(("get the missing glue and see if it's finally enough"));
217	if ((n = get_glue(statp, class, opts, &nsrrs)) >= 0)
218		n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
219
220 done:
221	DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
222	free_nsrrset(&nsrrs);
223	statp->pfcode = save_pfcode;
224	return (n);
225}
226
227/* Private. */
228
229static int
230satisfy(res_state statp, const char *mname, rrset_ns *nsrrsp,
231	union res_sockaddr_union *addrs, int naddrs)
232{
233	rr_ns *nsrr;
234	int n, x;
235
236	n = 0;
237	nsrr = find_ns(nsrrsp, mname);
238	if (nsrr != NULL) {
239		x = add_addrs(statp, nsrr, addrs, naddrs);
240		addrs += x;
241		naddrs -= x;
242		n += x;
243	}
244	for (nsrr = HEAD(*nsrrsp);
245	     nsrr != NULL && naddrs > 0;
246	     nsrr = NEXT(nsrr, link))
247		if (ns_samename(nsrr->name, mname) != 1) {
248			x = add_addrs(statp, nsrr, addrs, naddrs);
249			addrs += x;
250			naddrs -= x;
251			n += x;
252		}
253	DPRINTF(("satisfy(%s): %d", mname, n));
254	return (n);
255}
256
257static int
258add_addrs(res_state statp, rr_ns *nsrr,
259	  union res_sockaddr_union *addrs, int naddrs)
260{
261	rr_a *arr;
262	int n = 0;
263
264	for (arr = HEAD(nsrr->addrs); arr != NULL; arr = NEXT(arr, link)) {
265		if (naddrs <= 0)
266			return (0);
267		*addrs++ = arr->addr;
268		naddrs--;
269		n++;
270	}
271	DPRINTF(("add_addrs: %d", n));
272	return (n);
273}
274
275static int
276get_soa(res_state statp, const char *dname, ns_class class, int opts,
277	char *zname, size_t zsize, char *mname, size_t msize,
278	rrset_ns *nsrrsp)
279{
280	char tname[NS_MAXDNAME];
281	u_char resp[NS_PACKETSZ];
282	int n, i, ancount, nscount;
283	ns_sect sect;
284	ns_msg msg;
285	u_int rcode;
286
287	/*
288	 * Find closest enclosing SOA, even if it's for the root zone.
289	 */
290
291	/* First canonicalize dname (exactly one unescaped trailing "."). */
292	if (ns_makecanon(dname, tname, sizeof tname) < 0)
293		return (-1);
294	dname = tname;
295
296	/* Now grovel the subdomains, hunting for an SOA answer or auth. */
297	for (;;) {
298		/* Leading or inter-label '.' are skipped here. */
299		while (*dname == '.')
300			dname++;
301
302		/* Is there an SOA? */
303		n = do_query(statp, dname, class, ns_t_soa, resp, &msg);
304		if (n < 0) {
305			DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
306				 dname, p_class(class), n));
307			return (-1);
308		}
309		if (n > 0) {
310			DPRINTF(("get_soa: CNAME or DNAME found"));
311			sect = ns_s_max, n = 0;
312		} else {
313			rcode = ns_msg_getflag(msg, ns_f_rcode);
314			ancount = ns_msg_count(msg, ns_s_an);
315			nscount = ns_msg_count(msg, ns_s_ns);
316			if (ancount > 0 && rcode == ns_r_noerror)
317				sect = ns_s_an, n = ancount;
318			else if (nscount > 0)
319				sect = ns_s_ns, n = nscount;
320			else
321				sect = ns_s_max, n = 0;
322		}
323		for (i = 0; i < n; i++) {
324			const char *t;
325			const u_char *rdata;
326			int rdlen;
327			ns_rr rr;
328
329			if (ns_parserr(&msg, sect, i, &rr) < 0) {
330				DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
331					 p_section(sect, ns_o_query), i));
332				return (-1);
333			}
334			if (ns_rr_type(rr) == ns_t_cname ||
335			    ns_rr_type(rr) == ns_t_dname)
336				break;
337			if (ns_rr_type(rr) != ns_t_soa ||
338			    ns_rr_class(rr) != class)
339				continue;
340			t = ns_rr_name(rr);
341			switch (sect) {
342			case ns_s_an:
343				if (ns_samedomain(dname, t) == 0) {
344					DPRINTF(("get_soa: ns_samedomain('%s', '%s') == 0",
345						 dname, t));
346					errno = EPROTOTYPE;
347					return (-1);
348				}
349				break;
350			case ns_s_ns:
351				if (ns_samename(dname, t) == 1 ||
352				    ns_samedomain(dname, t) == 0) {
353					DPRINTF(("get_soa: ns_samename() || !ns_samedomain('%s', '%s')",
354						 dname, t));
355					errno = EPROTOTYPE;
356					return (-1);
357				}
358				break;
359			default:
360				abort();
361			}
362			if (strlen(t) + 1 > zsize) {
363				DPRINTF(("get_soa: zname(%d) too small (%d)",
364					 zsize, strlen(t) + 1));
365				errno = EMSGSIZE;
366				return (-1);
367			}
368			strcpy(zname, t);
369			rdata = ns_rr_rdata(rr);
370			rdlen = ns_rr_rdlen(rr);
371			if (ns_name_uncompress(resp, ns_msg_end(msg), rdata,
372					       mname, msize) < 0) {
373				DPRINTF(("get_soa: ns_name_uncompress failed"));
374				return (-1);
375			}
376			if (save_ns(statp, &msg, ns_s_ns,
377				    zname, class, opts, nsrrsp) < 0) {
378				DPRINTF(("get_soa: save_ns failed"));
379				return (-1);
380			}
381			return (0);
382		}
383
384		/* If we're out of labels, then not even "." has an SOA! */
385		if (*dname == '\0')
386			break;
387
388		/* Find label-terminating "."; top of loop will skip it. */
389		while (*dname != '.') {
390			if (*dname == '\\')
391				if (*++dname == '\0') {
392					errno = EMSGSIZE;
393					return (-1);
394				}
395			dname++;
396		}
397	}
398	DPRINTF(("get_soa: out of labels"));
399	errno = EDESTADDRREQ;
400	return (-1);
401}
402
403static int
404get_ns(res_state statp, const char *zname, ns_class class, int opts,
405      rrset_ns *nsrrsp)
406{
407	u_char resp[NS_PACKETSZ];
408	ns_msg msg;
409	int n;
410
411	/* Go and get the NS RRs for this zone. */
412	n = do_query(statp, zname, class, ns_t_ns, resp, &msg);
413	if (n != 0) {
414		DPRINTF(("get_ns: do_query('%s', %s) failed (%d)",
415			 zname, p_class(class), n));
416		return (-1);
417	}
418
419	/* Remember the NS RRs and associated A RRs that came back. */
420	if (save_ns(statp, &msg, ns_s_an, zname, class, opts, nsrrsp) < 0) {
421		DPRINTF(("get_ns save_ns('%s', %s) failed",
422			 zname, p_class(class)));
423		return (-1);
424	}
425
426	return (0);
427}
428
429static int
430get_glue(res_state statp, ns_class class, int opts, rrset_ns *nsrrsp) {
431	rr_ns *nsrr, *nsrr_n;
432
433	/* Go and get the A RRs for each empty NS RR on our list. */
434	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
435		u_char resp[NS_PACKETSZ];
436		ns_msg msg;
437		int n;
438
439		nsrr_n = NEXT(nsrr, link);
440
441		if (!nsrr->have_v4) {
442			n = do_query(statp, nsrr->name, class, ns_t_a,
443				     resp, &msg);
444			if (n < 0) {
445				DPRINTF(("get_glue: do_query('%s', %s') failed",
446					 nsrr->name, p_class(class)));
447				return (-1);
448			}
449			if (n > 0) {
450				DPRINTF((
451			"get_glue: do_query('%s', %s') CNAME or DNAME found",
452					 nsrr->name, p_class(class)));
453			}
454			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
455				   opts, nsrr) < 0) {
456				DPRINTF(("get_glue: save_r('%s', %s) failed",
457					 nsrr->name, p_class(class)));
458				return (-1);
459			}
460		}
461
462		if (!nsrr->have_v6) {
463			n = do_query(statp, nsrr->name, class, ns_t_aaaa,
464				     resp, &msg);
465			if (n < 0) {
466				DPRINTF(("get_glue: do_query('%s', %s') failed",
467					 nsrr->name, p_class(class)));
468				return (-1);
469			}
470			if (n > 0) {
471				DPRINTF((
472			"get_glue: do_query('%s', %s') CNAME or DNAME found",
473					 nsrr->name, p_class(class)));
474			}
475			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
476				   opts, nsrr) < 0) {
477				DPRINTF(("get_glue: save_r('%s', %s) failed",
478					 nsrr->name, p_class(class)));
479				return (-1);
480			}
481		}
482
483		/* If it's still empty, it's just chaff. */
484		if (EMPTY(nsrr->addrs)) {
485			DPRINTF(("get_glue: removing empty '%s' NS",
486				 nsrr->name));
487			free_nsrr(nsrrsp, nsrr);
488		}
489	}
490	return (0);
491}
492
493static int
494save_ns(res_state statp, ns_msg *msg, ns_sect sect,
495	const char *owner, ns_class class, int opts,
496	rrset_ns *nsrrsp)
497{
498	int i;
499
500	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
501		char tname[NS_MAXDNAME];
502		const u_char *rdata;
503		rr_ns *nsrr;
504		ns_rr rr;
505		int rdlen;
506
507		if (ns_parserr(msg, sect, i, &rr) < 0) {
508			DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
509				 p_section(sect, ns_o_query), i));
510			return (-1);
511		}
512		if (ns_rr_type(rr) != ns_t_ns ||
513		    ns_rr_class(rr) != class ||
514		    ns_samename(ns_rr_name(rr), owner) != 1)
515			continue;
516		nsrr = find_ns(nsrrsp, ns_rr_name(rr));
517		if (nsrr == NULL) {
518			nsrr = malloc(sizeof *nsrr);
519			if (nsrr == NULL) {
520				DPRINTF(("save_ns: malloc failed"));
521				return (-1);
522			}
523			rdata = ns_rr_rdata(rr);
524			rdlen = ns_rr_rdlen(rr);
525			if (ns_name_uncompress(ns_msg_base(*msg),
526					       ns_msg_end(*msg), rdata,
527					       tname, sizeof tname) < 0) {
528				DPRINTF(("save_ns: ns_name_uncompress failed"));
529				free(nsrr);
530				return (-1);
531			}
532			nsrr->name = strdup(tname);
533			if (nsrr->name == NULL) {
534				DPRINTF(("save_ns: strdup failed"));
535				free(nsrr);
536				return (-1);
537			}
538			INIT_LINK(nsrr, link);
539			INIT_LIST(nsrr->addrs);
540			nsrr->have_v4 = 0;
541			nsrr->have_v6 = 0;
542			APPEND(*nsrrsp, nsrr, link);
543		}
544		if (save_a(statp, msg, ns_s_ar,
545			   nsrr->name, class, opts, nsrr) < 0) {
546			DPRINTF(("save_ns: save_r('%s', %s) failed",
547				 nsrr->name, p_class(class)));
548			return (-1);
549		}
550	}
551	return (0);
552}
553
554static int
555save_a(res_state statp, ns_msg *msg, ns_sect sect,
556       const char *owner, ns_class class, int opts,
557       rr_ns *nsrr)
558{
559	int i;
560
561	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
562		ns_rr rr;
563		rr_a *arr;
564
565		if (ns_parserr(msg, sect, i, &rr) < 0) {
566			DPRINTF(("save_a: ns_parserr(%s, %d) failed",
567				 p_section(sect, ns_o_query), i));
568			return (-1);
569		}
570		if ((ns_rr_type(rr) != ns_t_a && ns_rr_type(rr) != ns_t_aaaa) ||
571		    ns_rr_class(rr) != class ||
572		    ns_samename(ns_rr_name(rr), owner) != 1 ||
573		    ns_rr_rdlen(rr) != NS_INADDRSZ)
574			continue;
575		if ((opts & RES_IPV6ONLY) != 0 && ns_rr_type(rr) != ns_t_aaaa)
576			continue;
577		if ((opts & RES_IPV4ONLY) != 0 && ns_rr_type(rr) != ns_t_a)
578			continue;
579		arr = malloc(sizeof *arr);
580		if (arr == NULL) {
581			DPRINTF(("save_a: malloc failed"));
582			return (-1);
583		}
584		INIT_LINK(arr, link);
585		memset(&arr->addr, 0, sizeof(arr->addr));
586		switch (ns_rr_type(rr)) {
587		case ns_t_a:
588			arr->addr.sin.sin_family = AF_INET;
589#ifdef HAVE_SA_LEN
590			arr->addr.sin.sin_len = sizeof(arr->addr.sin);
591#endif
592			memcpy(&arr->addr.sin.sin_addr, ns_rr_rdata(rr),
593			       NS_INADDRSZ);
594			arr->addr.sin.sin_port = htons(NS_DEFAULTPORT);
595			nsrr->have_v4 = 1;
596			break;
597		case ns_t_aaaa:
598			arr->addr.sin6.sin6_family = AF_INET6;
599#ifdef HAVE_SA_LEN
600			arr->addr.sin6.sin6_len = sizeof(arr->addr.sin6);
601#endif
602			memcpy(&arr->addr.sin6.sin6_addr, ns_rr_rdata(rr), 16);
603			arr->addr.sin.sin_port = htons(NS_DEFAULTPORT);
604			nsrr->have_v6 = 1;
605			break;
606		default:
607			abort();
608		}
609		APPEND(nsrr->addrs, arr, link);
610	}
611	return (0);
612}
613
614static void
615free_nsrrset(rrset_ns *nsrrsp) {
616	rr_ns *nsrr;
617
618	while ((nsrr = HEAD(*nsrrsp)) != NULL)
619		free_nsrr(nsrrsp, nsrr);
620}
621
622static void
623free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
624	rr_a *arr;
625	char *tmp;
626
627	while ((arr = HEAD(nsrr->addrs)) != NULL) {
628		UNLINK(nsrr->addrs, arr, link);
629		free(arr);
630	}
631#ifdef __APPLE__
632	tmp = (char *)nsrr->name;
633#else
634	DE_CONST(nsrr->name, tmp);
635#endif
636	free(tmp);
637	UNLINK(*nsrrsp, nsrr, link);
638	free(nsrr);
639}
640
641static rr_ns *
642find_ns(rrset_ns *nsrrsp, const char *dname) {
643	rr_ns *nsrr;
644
645	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = NEXT(nsrr, link))
646		if (ns_samename(nsrr->name, dname) == 1)
647			return (nsrr);
648	return (NULL);
649}
650
651static int
652do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
653	 u_char *resp, ns_msg *msg)
654{
655	u_char req[NS_PACKETSZ];
656	int i, n;
657
658	n = res_nmkquery(statp, ns_o_query, dname, class, qtype,
659			 NULL, 0, NULL, req, NS_PACKETSZ);
660	if (n < 0) {
661		DPRINTF(("do_query: res_nmkquery failed"));
662		return (-1);
663	}
664	n = res_nsend(statp, req, n, resp, NS_PACKETSZ);
665	if (n < 0) {
666		DPRINTF(("do_query: res_nsend failed"));
667		return (-1);
668	}
669	if (n == 0) {
670		DPRINTF(("do_query: res_nsend returned 0"));
671		errno = EMSGSIZE;
672		return (-1);
673	}
674	if (ns_initparse(resp, n, msg) < 0) {
675		DPRINTF(("do_query: ns_initparse failed"));
676		return (-1);
677	}
678	n = 0;
679	for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
680		ns_rr rr;
681
682		if (ns_parserr(msg, ns_s_an, i, &rr) < 0) {
683			DPRINTF(("do_query: ns_parserr failed"));
684			return (-1);
685		}
686		n += (ns_rr_class(rr) == class &&
687		      (ns_rr_type(rr) == ns_t_cname ||
688		       ns_rr_type(rr) == ns_t_dname));
689	}
690	return (n);
691}
692
693static void
694res_dprintf(const char *fmt, ...) {
695	va_list ap;
696
697	va_start(ap, fmt);
698	fputs(";; res_findzonecut: ", stderr);
699	vfprintf(stderr, fmt, ap);
700	fputc('\n', stderr);
701	va_end(ap);
702}
703