1#if !defined(lint) && !defined(SABER)
2static const char rcsid[] = "$Id: res_findzonecut.c,v 1.10 2005/10/11 00:10:16 marka Exp $";
3#endif /* not lint */
4
5/*
6 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
7 * Copyright (c) 1999 by Internet Software Consortium.
8 *
9 * Permission to use, copy, modify, and distribute this software for any
10 * purpose with or without fee is hereby granted, provided that the above
11 * copyright notice and this permission notice appear in all copies.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
14 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
15 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
16 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
17 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
18 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
19 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
20 */
21
22/* Import. */
23
24#include "port_before.h"
25
26#include <sys/param.h>
27#include <sys/socket.h>
28#include <sys/time.h>
29
30#include <netinet/in.h>
31#include <arpa/inet.h>
32#include <arpa/nameser.h>
33
34#include <errno.h>
35#include <limits.h>
36#include <netdb.h>
37#include <stdarg.h>
38#include <stdio.h>
39#include <stdlib.h>
40#include <string.h>
41
42#include <isc/list.h>
43
44#include "port_after.h"
45
46#include <resolv.h>
47
48/* Data structures. */
49
50typedef struct rr_a {
51	LINK(struct rr_a)	link;
52	union res_sockaddr_union addr;
53} rr_a;
54typedef LIST(rr_a) rrset_a;
55
56typedef struct rr_ns {
57	LINK(struct rr_ns)	link;
58	const char *		name;
59	unsigned int		flags;
60	rrset_a			addrs;
61} rr_ns;
62typedef LIST(rr_ns) rrset_ns;
63
64#define	RR_NS_HAVE_V4		0x01
65#define	RR_NS_HAVE_V6		0x02
66
67/* Forward. */
68
69static int	satisfy(res_state, const char *, rrset_ns *,
70			union res_sockaddr_union *, int);
71static int	add_addrs(res_state, rr_ns *,
72			  union res_sockaddr_union *, int);
73static int	get_soa(res_state, const char *, ns_class, int,
74			char *, size_t, char *, size_t,
75			rrset_ns *);
76static int	get_ns(res_state, const char *, ns_class, int, rrset_ns *);
77static int	get_glue(res_state, ns_class, int, rrset_ns *);
78static int	save_ns(res_state, ns_msg *, ns_sect,
79			const char *, ns_class, int, rrset_ns *);
80static int	save_a(res_state, ns_msg *, ns_sect,
81		       const char *, ns_class, int, rr_ns *);
82static void	free_nsrrset(rrset_ns *);
83static void	free_nsrr(rrset_ns *, rr_ns *);
84static rr_ns *	find_ns(rrset_ns *, const char *);
85static int	do_query(res_state, const char *, ns_class, ns_type,
86			 u_char *, ns_msg *);
87static void	res_dprintf(const char *, ...) ISC_FORMAT_PRINTF(1, 2);
88
89/* Macros. */
90
91#define DPRINTF(x) do {\
92		int save_errno = errno; \
93		if ((statp->options & RES_DEBUG) != 0U) res_dprintf x; \
94		errno = save_errno; \
95	} while (0)
96
97/* Public. */
98
99/*%
100 *	find enclosing zone for a <dname,class>, and some server addresses
101 *
102 * parameters:
103 *\li	res - resolver context to work within (is modified)
104 *\li	dname - domain name whose enclosing zone is desired
105 *\li	class - class of dname (and its enclosing zone)
106 *\li	zname - found zone name
107 *\li	zsize - allocated size of zname
108 *\li	addrs - found server addresses
109 *\li	naddrs - max number of addrs
110 *
111 * return values:
112 *\li	< 0 - an error occurred (check errno)
113 *\li	= 0 - zname is now valid, but addrs[] wasn't changed
114 *\li	> 0 - zname is now valid, and return value is number of addrs[] found
115 *
116 * notes:
117 *\li	this function calls res_nsend() which means it depends on correctly
118 *	functioning recursive nameservers (usually defined in /etc/resolv.conf
119 *	or its local equivilent).
120 *
121 *\li	we start by asking for an SOA<dname,class>.  if we get one as an
122 *	answer, that just means <dname,class> is a zone top, which is fine.
123 *	more than likely we'll be told to go pound sand, in the form of a
124 *	negative answer.
125 *
126 *\li	note that we are not prepared to deal with referrals since that would
127 *	only come from authority servers and our correctly functioning local
128 *	recursive server would have followed the referral and got us something
129 *	more definite.
130 *
131 *\li	if the authority section contains an SOA, this SOA should also be the
132 *	closest enclosing zone, since any intermediary zone cuts would've been
133 *	returned as referrals and dealt with by our correctly functioning local
134 *	recursive name server.  but an SOA in the authority section should NOT
135 *	match our dname (since that would have been returned in the answer
136 *	section).  an authority section SOA has to be "above" our dname.
137 *
138 *\li	however, since authority section SOA's were once optional, it's
139 *	possible that we'll have to go hunting for the enclosing SOA by
140 *	ripping labels off the front of our dname -- this is known as "doing
141 *	it the hard way."
142 *
143 *\li	ultimately we want some server addresses, which are ideally the ones
144 *	pertaining to the SOA.MNAME, but only if there is a matching NS RR.
145 *	so the second phase (after we find an SOA) is to go looking for the
146 *	NS RRset for that SOA's zone.
147 *
148 *\li	no answer section processed by this code is allowed to contain CNAME
149 *	or DNAME RR's.  for the SOA query this means we strip a label and
150 *	keep going.  for the NS and A queries this means we just give up.
151 */
152
153int
154res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
155		char *zname, size_t zsize, struct in_addr *addrs, int naddrs)
156{
157	int result, i;
158	union res_sockaddr_union *u;
159
160
161	opts |= RES_IPV4ONLY;
162	opts &= ~RES_IPV6ONLY;
163
164	u = calloc(naddrs, sizeof(*u));
165	if (u == NULL)
166		return(-1);
167
168	result = res_findzonecut2(statp, dname, class, opts, zname, zsize,
169				  u, naddrs);
170
171	for (i = 0; i < result; i++) {
172		addrs[i] = u[i].sin.sin_addr;
173	}
174	free(u);
175	return (result);
176}
177
178int
179res_findzonecut2(res_state statp, const char *dname, ns_class class, int opts,
180		 char *zname, size_t zsize, union res_sockaddr_union *addrs,
181		 int naddrs)
182{
183	char mname[NS_MAXDNAME];
184	u_long save_pfcode;
185	rrset_ns nsrrs;
186	int n;
187
188	DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
189		 dname, p_class(class), (long)zsize, naddrs));
190	save_pfcode = statp->pfcode;
191	statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
192			 RES_PRF_QUES | RES_PRF_ANS |
193			 RES_PRF_AUTH | RES_PRF_ADD;
194	INIT_LIST(nsrrs);
195
196	DPRINTF(("get the soa, and see if it has enough glue"));
197	if ((n = get_soa(statp, dname, class, opts, zname, zsize,
198			 mname, sizeof mname, &nsrrs)) < 0 ||
199	    ((opts & RES_EXHAUSTIVE) == 0 &&
200	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
201		goto done;
202
203	DPRINTF(("get the ns rrset and see if it has enough glue"));
204	if ((n = get_ns(statp, zname, class, opts, &nsrrs)) < 0 ||
205	    ((opts & RES_EXHAUSTIVE) == 0 &&
206	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
207		goto done;
208
209	DPRINTF(("get the missing glue and see if it's finally enough"));
210	if ((n = get_glue(statp, class, opts, &nsrrs)) >= 0)
211		n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
212
213 done:
214	DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
215	free_nsrrset(&nsrrs);
216	statp->pfcode = save_pfcode;
217	return (n);
218}
219
220/* Private. */
221
222static int
223satisfy(res_state statp, const char *mname, rrset_ns *nsrrsp,
224	union res_sockaddr_union *addrs, int naddrs)
225{
226	rr_ns *nsrr;
227	int n, x;
228
229	n = 0;
230	nsrr = find_ns(nsrrsp, mname);
231	if (nsrr != NULL) {
232		x = add_addrs(statp, nsrr, addrs, naddrs);
233		addrs += x;
234		naddrs -= x;
235		n += x;
236	}
237	for (nsrr = HEAD(*nsrrsp);
238	     nsrr != NULL && naddrs > 0;
239	     nsrr = NEXT(nsrr, link))
240		if (ns_samename(nsrr->name, mname) != 1) {
241			x = add_addrs(statp, nsrr, addrs, naddrs);
242			addrs += x;
243			naddrs -= x;
244			n += x;
245		}
246	DPRINTF(("satisfy(%s): %d", mname, n));
247	return (n);
248}
249
250static int
251add_addrs(res_state statp, rr_ns *nsrr,
252	  union res_sockaddr_union *addrs, int naddrs)
253{
254	rr_a *arr;
255	int n = 0;
256
257	for (arr = HEAD(nsrr->addrs); arr != NULL; arr = NEXT(arr, link)) {
258		if (naddrs <= 0)
259			return (0);
260		*addrs++ = arr->addr;
261		naddrs--;
262		n++;
263	}
264	DPRINTF(("add_addrs: %d", n));
265	return (n);
266}
267
268static int
269get_soa(res_state statp, const char *dname, ns_class class, int opts,
270	char *zname, size_t zsize, char *mname, size_t msize,
271	rrset_ns *nsrrsp)
272{
273	char tname[NS_MAXDNAME];
274	u_char *resp = NULL;
275	int n, i, ancount, nscount;
276	ns_sect sect;
277	ns_msg msg;
278	u_int rcode;
279
280	/*
281	 * Find closest enclosing SOA, even if it's for the root zone.
282	 */
283
284	/* First canonicalize dname (exactly one unescaped trailing "."). */
285	if (ns_makecanon(dname, tname, sizeof tname) < 0)
286		goto cleanup;
287	dname = tname;
288
289	resp = malloc(NS_MAXMSG);
290	if (resp == NULL)
291		goto cleanup;
292
293	/* Now grovel the subdomains, hunting for an SOA answer or auth. */
294	for (;;) {
295		/* Leading or inter-label '.' are skipped here. */
296		while (*dname == '.')
297			dname++;
298
299		/* Is there an SOA? */
300		n = do_query(statp, dname, class, ns_t_soa, resp, &msg);
301		if (n < 0) {
302			DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
303				 dname, p_class(class), n));
304			goto cleanup;
305		}
306		if (n > 0) {
307			DPRINTF(("get_soa: CNAME or DNAME found"));
308			sect = ns_s_max, n = 0;
309		} else {
310			rcode = ns_msg_getflag(msg, ns_f_rcode);
311			ancount = ns_msg_count(msg, ns_s_an);
312			nscount = ns_msg_count(msg, ns_s_ns);
313			if (ancount > 0 && rcode == ns_r_noerror)
314				sect = ns_s_an, n = ancount;
315			else if (nscount > 0)
316				sect = ns_s_ns, n = nscount;
317			else
318				sect = ns_s_max, n = 0;
319		}
320		for (i = 0; i < n; i++) {
321			const char *t;
322			const u_char *rdata;
323			ns_rr rr;
324
325			if (ns_parserr(&msg, sect, i, &rr) < 0) {
326				DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
327					 p_section(sect, ns_o_query), i));
328				goto cleanup;
329			}
330			if (ns_rr_type(rr) == ns_t_cname ||
331			    ns_rr_type(rr) == ns_t_dname)
332				break;
333			if (ns_rr_type(rr) != ns_t_soa ||
334			    ns_rr_class(rr) != class)
335				continue;
336			t = ns_rr_name(rr);
337			switch (sect) {
338			case ns_s_an:
339				if (ns_samedomain(dname, t) == 0) {
340					DPRINTF(
341				    ("get_soa: ns_samedomain('%s', '%s') == 0",
342						dname, t)
343						);
344					errno = EPROTOTYPE;
345					goto cleanup;
346				}
347				break;
348			case ns_s_ns:
349				if (ns_samename(dname, t) == 1 ||
350				    ns_samedomain(dname, t) == 0) {
351					DPRINTF(
352		       ("get_soa: ns_samename() || !ns_samedomain('%s', '%s')",
353						dname, t)
354						);
355					errno = EPROTOTYPE;
356					goto cleanup;
357				}
358				break;
359			default:
360				abort();
361			}
362			if (strlen(t) + 1 > zsize) {
363				DPRINTF(("get_soa: zname(%lu) too small (%lu)",
364					 (unsigned long)zsize,
365					 (unsigned long)strlen(t) + 1));
366				errno = EMSGSIZE;
367				goto cleanup;
368			}
369			strcpy(zname, t);
370			rdata = ns_rr_rdata(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					);
375				goto cleanup;
376			}
377			if (save_ns(statp, &msg, ns_s_ns,
378				    zname, class, opts, nsrrsp) < 0) {
379				DPRINTF(("get_soa: save_ns failed"));
380				goto cleanup;
381			}
382			free(resp);
383			return (0);
384		}
385
386		/* If we're out of labels, then not even "." has an SOA! */
387		if (*dname == '\0')
388			break;
389
390		/* Find label-terminating "."; top of loop will skip it. */
391		while (*dname != '.') {
392			if (*dname == '\\')
393				if (*++dname == '\0') {
394					errno = EMSGSIZE;
395					goto cleanup;
396				}
397			dname++;
398		}
399	}
400	DPRINTF(("get_soa: out of labels"));
401	errno = EDESTADDRREQ;
402 cleanup:
403	if (resp != NULL)
404		free(resp);
405	return (-1);
406}
407
408static int
409get_ns(res_state statp, const char *zname, ns_class class, int opts,
410      rrset_ns *nsrrsp)
411{
412	u_char *resp;
413	ns_msg msg;
414	int n;
415
416	resp = malloc(NS_MAXMSG);
417	if (resp == NULL)
418		return (-1);
419
420	/* Go and get the NS RRs for this zone. */
421	n = do_query(statp, zname, class, ns_t_ns, resp, &msg);
422	if (n != 0) {
423		DPRINTF(("get_ns: do_query('%s', %s) failed (%d)",
424			 zname, p_class(class), n));
425		free(resp);
426		return (-1);
427	}
428
429	/* Remember the NS RRs and associated A RRs that came back. */
430	if (save_ns(statp, &msg, ns_s_an, zname, class, opts, nsrrsp) < 0) {
431		DPRINTF(("get_ns save_ns('%s', %s) failed",
432			 zname, p_class(class)));
433		free(resp);
434		return (-1);
435	}
436
437	free(resp);
438	return (0);
439}
440
441static int
442get_glue(res_state statp, ns_class class, int opts, rrset_ns *nsrrsp) {
443	rr_ns *nsrr, *nsrr_n;
444	u_char *resp;
445
446	resp = malloc(NS_MAXMSG);
447	if (resp == NULL)
448		return(-1);
449
450	/* Go and get the A RRs for each empty NS RR on our list. */
451	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
452		ns_msg msg;
453		int n;
454
455		nsrr_n = NEXT(nsrr, link);
456
457		if ((nsrr->flags & RR_NS_HAVE_V4) == 0) {
458			n = do_query(statp, nsrr->name, class, ns_t_a,
459				     resp, &msg);
460			if (n < 0) {
461				DPRINTF(
462				       ("get_glue: do_query('%s', %s') failed",
463					nsrr->name, p_class(class)));
464				goto cleanup;
465			}
466			if (n > 0) {
467				DPRINTF((
468			"get_glue: do_query('%s', %s') CNAME or DNAME found",
469					 nsrr->name, p_class(class)));
470			}
471			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
472				   opts, nsrr) < 0) {
473				DPRINTF(("get_glue: save_r('%s', %s) failed",
474					 nsrr->name, p_class(class)));
475				goto cleanup;
476			}
477		}
478
479		if ((nsrr->flags & RR_NS_HAVE_V6) == 0) {
480			n = do_query(statp, nsrr->name, class, ns_t_aaaa,
481				     resp, &msg);
482			if (n < 0) {
483				DPRINTF(
484				       ("get_glue: do_query('%s', %s') failed",
485					nsrr->name, p_class(class)));
486				goto cleanup;
487			}
488			if (n > 0) {
489				DPRINTF((
490			"get_glue: do_query('%s', %s') CNAME or DNAME found",
491					 nsrr->name, p_class(class)));
492			}
493			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
494				   opts, nsrr) < 0) {
495				DPRINTF(("get_glue: save_r('%s', %s) failed",
496					 nsrr->name, p_class(class)));
497				goto cleanup;
498			}
499		}
500
501		/* If it's still empty, it's just chaff. */
502		if (EMPTY(nsrr->addrs)) {
503			DPRINTF(("get_glue: removing empty '%s' NS",
504				 nsrr->name));
505			free_nsrr(nsrrsp, nsrr);
506		}
507	}
508	free(resp);
509	return (0);
510
511 cleanup:
512	free(resp);
513	return (-1);
514}
515
516static int
517save_ns(res_state statp, ns_msg *msg, ns_sect sect,
518	const char *owner, ns_class class, int opts,
519	rrset_ns *nsrrsp)
520{
521	int i;
522
523	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
524		char tname[MAXDNAME];
525		const u_char *rdata;
526		rr_ns *nsrr;
527		ns_rr rr;
528
529		if (ns_parserr(msg, sect, i, &rr) < 0) {
530			DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
531				 p_section(sect, ns_o_query), i));
532			return (-1);
533		}
534		if (ns_rr_type(rr) != ns_t_ns ||
535		    ns_rr_class(rr) != class ||
536		    ns_samename(ns_rr_name(rr), owner) != 1)
537			continue;
538		nsrr = find_ns(nsrrsp, ns_rr_name(rr));
539		if (nsrr == NULL) {
540			nsrr = malloc(sizeof *nsrr);
541			if (nsrr == NULL) {
542				DPRINTF(("save_ns: malloc failed"));
543				return (-1);
544			}
545			rdata = ns_rr_rdata(rr);
546			if (ns_name_uncompress(ns_msg_base(*msg),
547					       ns_msg_end(*msg), rdata,
548					       tname, sizeof tname) < 0) {
549				DPRINTF(("save_ns: ns_name_uncompress failed")
550					);
551				free(nsrr);
552				return (-1);
553			}
554			nsrr->name = strdup(tname);
555			if (nsrr->name == NULL) {
556				DPRINTF(("save_ns: strdup failed"));
557				free(nsrr);
558				return (-1);
559			}
560			INIT_LINK(nsrr, link);
561			INIT_LIST(nsrr->addrs);
562			nsrr->flags = 0;
563			APPEND(*nsrrsp, nsrr, link);
564		}
565		if (save_a(statp, msg, ns_s_ar,
566			   nsrr->name, class, opts, nsrr) < 0) {
567			DPRINTF(("save_ns: save_r('%s', %s) failed",
568				 nsrr->name, p_class(class)));
569			return (-1);
570		}
571	}
572	return (0);
573}
574
575static int
576save_a(res_state statp, ns_msg *msg, ns_sect sect,
577       const char *owner, ns_class class, int opts,
578       rr_ns *nsrr)
579{
580	int i;
581
582	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
583		ns_rr rr;
584		rr_a *arr;
585
586		if (ns_parserr(msg, sect, i, &rr) < 0) {
587			DPRINTF(("save_a: ns_parserr(%s, %d) failed",
588				 p_section(sect, ns_o_query), i));
589			return (-1);
590		}
591		if ((ns_rr_type(rr) != ns_t_a &&
592		     ns_rr_type(rr) != ns_t_aaaa) ||
593		    ns_rr_class(rr) != class ||
594		    ns_samename(ns_rr_name(rr), owner) != 1 ||
595		    ns_rr_rdlen(rr) != NS_INADDRSZ)
596			continue;
597		if ((opts & RES_IPV6ONLY) != 0 && ns_rr_type(rr) != ns_t_aaaa)
598			continue;
599		if ((opts & RES_IPV4ONLY) != 0 && ns_rr_type(rr) != ns_t_a)
600			continue;
601		arr = malloc(sizeof *arr);
602		if (arr == NULL) {
603			DPRINTF(("save_a: malloc failed"));
604			return (-1);
605		}
606		INIT_LINK(arr, link);
607		memset(&arr->addr, 0, sizeof(arr->addr));
608		switch (ns_rr_type(rr)) {
609		case ns_t_a:
610			arr->addr.sin.sin_family = AF_INET;
611#ifdef HAVE_SA_LEN
612			arr->addr.sin.sin_len = sizeof(arr->addr.sin);
613#endif
614			memcpy(&arr->addr.sin.sin_addr, ns_rr_rdata(rr),
615			       NS_INADDRSZ);
616			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
617			nsrr->flags |= RR_NS_HAVE_V4;
618			break;
619		case ns_t_aaaa:
620			arr->addr.sin6.sin6_family = AF_INET6;
621#ifdef HAVE_SA_LEN
622			arr->addr.sin6.sin6_len = sizeof(arr->addr.sin6);
623#endif
624			memcpy(&arr->addr.sin6.sin6_addr, ns_rr_rdata(rr), 16);
625			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
626			nsrr->flags |= RR_NS_HAVE_V6;
627			break;
628		default:
629			abort();
630		}
631		APPEND(nsrr->addrs, arr, link);
632	}
633	return (0);
634}
635
636static void
637free_nsrrset(rrset_ns *nsrrsp) {
638	rr_ns *nsrr;
639
640	while ((nsrr = HEAD(*nsrrsp)) != NULL)
641		free_nsrr(nsrrsp, nsrr);
642}
643
644static void
645free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
646	rr_a *arr;
647	char *tmp;
648
649	while ((arr = HEAD(nsrr->addrs)) != NULL) {
650		UNLINK(nsrr->addrs, arr, link);
651		free(arr);
652	}
653	DE_CONST(nsrr->name, tmp);
654	free(tmp);
655	UNLINK(*nsrrsp, nsrr, link);
656	free(nsrr);
657}
658
659static rr_ns *
660find_ns(rrset_ns *nsrrsp, const char *dname) {
661	rr_ns *nsrr;
662
663	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = NEXT(nsrr, link))
664		if (ns_samename(nsrr->name, dname) == 1)
665			return (nsrr);
666	return (NULL);
667}
668
669static int
670do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
671	 u_char *resp, ns_msg *msg)
672{
673	u_char req[NS_PACKETSZ];
674	int i, n;
675
676	n = res_nmkquery(statp, ns_o_query, dname, class, qtype,
677			 NULL, 0, NULL, req, NS_PACKETSZ);
678	if (n < 0) {
679		DPRINTF(("do_query: res_nmkquery failed"));
680		return (-1);
681	}
682	n = res_nsend(statp, req, n, resp, NS_MAXMSG);
683	if (n < 0) {
684		DPRINTF(("do_query: res_nsend failed"));
685		return (-1);
686	}
687	if (n == 0) {
688		DPRINTF(("do_query: res_nsend returned 0"));
689		errno = EMSGSIZE;
690		return (-1);
691	}
692	if (ns_initparse(resp, n, msg) < 0) {
693		DPRINTF(("do_query: ns_initparse failed"));
694		return (-1);
695	}
696	n = 0;
697	for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
698		ns_rr rr;
699
700		if (ns_parserr(msg, ns_s_an, i, &rr) < 0) {
701			DPRINTF(("do_query: ns_parserr failed"));
702			return (-1);
703		}
704		n += (ns_rr_class(rr) == class &&
705		      (ns_rr_type(rr) == ns_t_cname ||
706		       ns_rr_type(rr) == ns_t_dname));
707	}
708	return (n);
709}
710
711static void
712res_dprintf(const char *fmt, ...) {
713	va_list ap;
714
715	va_start(ap, fmt);
716	fputs(";; res_findzonecut: ", stderr);
717	vfprintf(stderr, fmt, ap);
718	fputc('\n', stderr);
719	va_end(ap);
720}
721
722/*! \file */
723