1/*
2 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
3 * Copyright (c) 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/* Import. */
19
20#include "port_before.h"
21
22#include <sys/param.h>
23#include <sys/socket.h>
24#include <sys/time.h>
25
26#include <netinet/in.h>
27#include <arpa/inet.h>
28#include <arpa/nameser.h>
29
30#include <errno.h>
31#include <limits.h>
32#include <netdb.h>
33#include <stdarg.h>
34#include <stdio.h>
35#include <stdlib.h>
36#include <string.h>
37
38#include <isc/list.h>
39
40#include "port_after.h"
41
42#include <resolv.h>
43
44/* Data structures. */
45
46typedef struct rr_a {
47	LINK(struct rr_a)	link;
48	union res_sockaddr_union addr;
49} rr_a;
50typedef LIST(rr_a) rrset_a;
51
52typedef struct rr_ns {
53	LINK(struct rr_ns)	link;
54	const char *		name;
55	unsigned int		flags;
56	rrset_a			addrs;
57} rr_ns;
58typedef LIST(rr_ns) rrset_ns;
59
60#define	RR_NS_HAVE_V4		0x01
61#define	RR_NS_HAVE_V6		0x02
62
63/* Forward. */
64
65static int	satisfy(res_state, const char *, rrset_ns *,
66			union res_sockaddr_union *, int);
67static int	add_addrs(res_state, rr_ns *,
68			  union res_sockaddr_union *, int);
69static int	get_soa(res_state, const char *, ns_class, int,
70			char *, size_t, char *, size_t,
71			rrset_ns *);
72static int	get_ns(res_state, const char *, ns_class, int, rrset_ns *);
73static int	get_glue(res_state, ns_class, int, rrset_ns *);
74static int	save_ns(res_state, ns_msg *, ns_sect,
75			const char *, ns_class, int, rrset_ns *);
76static int	save_a(res_state, ns_msg *, ns_sect,
77		       const char *, ns_class, int, rr_ns *);
78static void	free_nsrrset(rrset_ns *);
79static void	free_nsrr(rrset_ns *, rr_ns *);
80static rr_ns *	find_ns(rrset_ns *, const char *);
81static int	do_query(res_state, const char *, ns_class, ns_type,
82			 u_char *, ns_msg *);
83static void	res_dprintf(const char *, ...) ISC_FORMAT_PRINTF(1, 2);
84
85/* Macros. */
86
87#define DPRINTF(x) do {\
88		int save_errno = errno; \
89		if ((statp->options & RES_DEBUG) != 0U) res_dprintf x; \
90		errno = save_errno; \
91	} while (0)
92
93/* Public. */
94
95/*%
96 *	find enclosing zone for a <dname,class>, and some server addresses
97 *
98 * parameters:
99 *\li	res - resolver context to work within (is modified)
100 *\li	dname - domain name whose enclosing zone is desired
101 *\li	class - class of dname (and its enclosing zone)
102 *\li	zname - found zone name
103 *\li	zsize - allocated size of zname
104 *\li	addrs - found server addresses
105 *\li	naddrs - max number of addrs
106 *
107 * return values:
108 *\li	< 0 - an error occurred (check errno)
109 *\li	= 0 - zname is now valid, but addrs[] wasn't changed
110 *\li	> 0 - zname is now valid, and return value is number of addrs[] found
111 *
112 * notes:
113 *\li	this function calls res_nsend() which means it depends on correctly
114 *	functioning recursive nameservers (usually defined in /etc/resolv.conf
115 *	or its local equivilent).
116 *
117 *\li	we start by asking for an SOA<dname,class>.  if we get one as an
118 *	answer, that just means <dname,class> is a zone top, which is fine.
119 *	more than likely we'll be told to go pound sand, in the form of a
120 *	negative answer.
121 *
122 *\li	note that we are not prepared to deal with referrals since that would
123 *	only come from authority servers and our correctly functioning local
124 *	recursive server would have followed the referral and got us something
125 *	more definite.
126 *
127 *\li	if the authority section contains an SOA, this SOA should also be the
128 *	closest enclosing zone, since any intermediary zone cuts would've been
129 *	returned as referrals and dealt with by our correctly functioning local
130 *	recursive name server.  but an SOA in the authority section should NOT
131 *	match our dname (since that would have been returned in the answer
132 *	section).  an authority section SOA has to be "above" our dname.
133 *
134 *\li	however, since authority section SOA's were once optional, it's
135 *	possible that we'll have to go hunting for the enclosing SOA by
136 *	ripping labels off the front of our dname -- this is known as "doing
137 *	it the hard way."
138 *
139 *\li	ultimately we want some server addresses, which are ideally the ones
140 *	pertaining to the SOA.MNAME, but only if there is a matching NS RR.
141 *	so the second phase (after we find an SOA) is to go looking for the
142 *	NS RRset for that SOA's zone.
143 *
144 *\li	no answer section processed by this code is allowed to contain CNAME
145 *	or DNAME RR's.  for the SOA query this means we strip a label and
146 *	keep going.  for the NS and A queries this means we just give up.
147 */
148
149int
150res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
151		char *zname, size_t zsize, struct in_addr *addrs, int naddrs)
152{
153	int result, i;
154	union res_sockaddr_union *u;
155
156
157	opts |= RES_IPV4ONLY;
158	opts &= ~RES_IPV6ONLY;
159
160	u = calloc(naddrs, sizeof(*u));
161	if (u == NULL)
162		return(-1);
163
164	result = res_findzonecut2(statp, dname, class, opts, zname, zsize,
165				  u, naddrs);
166
167	for (i = 0; i < result; i++) {
168		addrs[i] = u[i].sin.sin_addr;
169	}
170	free(u);
171	return (result);
172}
173
174int
175res_findzonecut2(res_state statp, const char *dname, ns_class class, int opts,
176		 char *zname, size_t zsize, union res_sockaddr_union *addrs,
177		 int naddrs)
178{
179	char mname[NS_MAXDNAME];
180	u_long save_pfcode;
181	rrset_ns nsrrs;
182	int n;
183
184	DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
185		 dname, p_class(class), (long)zsize, naddrs));
186	save_pfcode = statp->pfcode;
187	statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
188			 RES_PRF_QUES | RES_PRF_ANS |
189			 RES_PRF_AUTH | RES_PRF_ADD;
190	INIT_LIST(nsrrs);
191
192	DPRINTF(("get the soa, and see if it has enough glue"));
193	if ((n = get_soa(statp, dname, class, opts, zname, zsize,
194			 mname, sizeof mname, &nsrrs)) < 0 ||
195	    ((opts & RES_EXHAUSTIVE) == 0 &&
196	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
197		goto done;
198
199	DPRINTF(("get the ns rrset and see if it has enough glue"));
200	if ((n = get_ns(statp, zname, class, opts, &nsrrs)) < 0 ||
201	    ((opts & RES_EXHAUSTIVE) == 0 &&
202	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
203		goto done;
204
205	DPRINTF(("get the missing glue and see if it's finally enough"));
206	if ((n = get_glue(statp, class, opts, &nsrrs)) >= 0)
207		n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
208
209 done:
210	DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
211	free_nsrrset(&nsrrs);
212	statp->pfcode = save_pfcode;
213	return (n);
214}
215
216/* Private. */
217
218static int
219satisfy(res_state statp, const char *mname, rrset_ns *nsrrsp,
220	union res_sockaddr_union *addrs, int naddrs)
221{
222	rr_ns *nsrr;
223	int n, x;
224
225	n = 0;
226	nsrr = find_ns(nsrrsp, mname);
227	if (nsrr != NULL) {
228		x = add_addrs(statp, nsrr, addrs, naddrs);
229		addrs += x;
230		naddrs -= x;
231		n += x;
232	}
233	for (nsrr = HEAD(*nsrrsp);
234	     nsrr != NULL && naddrs > 0;
235	     nsrr = NEXT(nsrr, link))
236		if (ns_samename(nsrr->name, mname) != 1) {
237			x = add_addrs(statp, nsrr, addrs, naddrs);
238			addrs += x;
239			naddrs -= x;
240			n += x;
241		}
242	DPRINTF(("satisfy(%s): %d", mname, n));
243	return (n);
244}
245
246static int
247add_addrs(res_state statp, rr_ns *nsrr,
248	  union res_sockaddr_union *addrs, int naddrs)
249{
250	rr_a *arr;
251	int n = 0;
252
253	for (arr = HEAD(nsrr->addrs); arr != NULL; arr = NEXT(arr, link)) {
254		if (naddrs <= 0)
255			return (0);
256		*addrs++ = arr->addr;
257		naddrs--;
258		n++;
259	}
260	DPRINTF(("add_addrs: %d", n));
261	return (n);
262}
263
264static int
265get_soa(res_state statp, const char *dname, ns_class class, int opts,
266	char *zname, size_t zsize, char *mname, size_t msize,
267	rrset_ns *nsrrsp)
268{
269	char tname[NS_MAXDNAME];
270	u_char *resp = NULL;
271	int n, i, ancount, nscount;
272	ns_sect sect;
273	ns_msg msg;
274	u_int rcode;
275
276	/*
277	 * Find closest enclosing SOA, even if it's for the root zone.
278	 */
279
280	/* First canonicalize dname (exactly one unescaped trailing "."). */
281	if (ns_makecanon(dname, tname, sizeof tname) < 0)
282		goto cleanup;
283	dname = tname;
284
285	resp = malloc(NS_MAXMSG);
286	if (resp == NULL)
287		goto cleanup;
288
289	/* Now grovel the subdomains, hunting for an SOA answer or auth. */
290	for (;;) {
291		/* Leading or inter-label '.' are skipped here. */
292		while (*dname == '.')
293			dname++;
294
295		/* Is there an SOA? */
296		n = do_query(statp, dname, class, ns_t_soa, resp, &msg);
297		if (n < 0) {
298			DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
299				 dname, p_class(class), n));
300			goto cleanup;
301		}
302		if (n > 0) {
303			DPRINTF(("get_soa: CNAME or DNAME found"));
304			sect = ns_s_max, n = 0;
305		} else {
306			rcode = ns_msg_getflag(msg, ns_f_rcode);
307			ancount = ns_msg_count(msg, ns_s_an);
308			nscount = ns_msg_count(msg, ns_s_ns);
309			if (ancount > 0 && rcode == ns_r_noerror)
310				sect = ns_s_an, n = ancount;
311			else if (nscount > 0)
312				sect = ns_s_ns, n = nscount;
313			else
314				sect = ns_s_max, n = 0;
315		}
316		for (i = 0; i < n; i++) {
317			const char *t;
318			const u_char *rdata;
319			ns_rr rr;
320
321			if (ns_parserr(&msg, sect, i, &rr) < 0) {
322				DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
323					 p_section(sect, ns_o_query), i));
324				goto cleanup;
325			}
326			if (ns_rr_type(rr) == ns_t_cname ||
327			    ns_rr_type(rr) == ns_t_dname)
328				break;
329			if (ns_rr_type(rr) != ns_t_soa ||
330			    ns_rr_class(rr) != class)
331				continue;
332			t = ns_rr_name(rr);
333			switch (sect) {
334			case ns_s_an:
335				if (ns_samedomain(dname, t) == 0) {
336					DPRINTF(
337				    ("get_soa: ns_samedomain('%s', '%s') == 0",
338						dname, t)
339						);
340					errno = EPROTOTYPE;
341					goto cleanup;
342				}
343				break;
344			case ns_s_ns:
345				if (ns_samename(dname, t) == 1 ||
346				    ns_samedomain(dname, t) == 0) {
347					DPRINTF(
348		       ("get_soa: ns_samename() || !ns_samedomain('%s', '%s')",
349						dname, t)
350						);
351					errno = EPROTOTYPE;
352					goto cleanup;
353				}
354				break;
355			default:
356				abort();
357			}
358			if (strlen(t) + 1 > zsize) {
359				DPRINTF(("get_soa: zname(%lu) too small (%lu)",
360					 (unsigned long)zsize,
361					 (unsigned long)strlen(t) + 1));
362				errno = EMSGSIZE;
363				goto cleanup;
364			}
365			strcpy(zname, t);
366			rdata = ns_rr_rdata(rr);
367			if (ns_name_uncompress(resp, ns_msg_end(msg), rdata,
368					       mname, msize) < 0) {
369				DPRINTF(("get_soa: ns_name_uncompress failed")
370					);
371				goto cleanup;
372			}
373			if (save_ns(statp, &msg, ns_s_ns,
374				    zname, class, opts, nsrrsp) < 0) {
375				DPRINTF(("get_soa: save_ns failed"));
376				goto cleanup;
377			}
378			free(resp);
379			return (0);
380		}
381
382		/* If we're out of labels, then not even "." has an SOA! */
383		if (*dname == '\0')
384			break;
385
386		/* Find label-terminating "."; top of loop will skip it. */
387		while (*dname != '.') {
388			if (*dname == '\\')
389				if (*++dname == '\0') {
390					errno = EMSGSIZE;
391					goto cleanup;
392				}
393			dname++;
394		}
395	}
396	DPRINTF(("get_soa: out of labels"));
397	errno = EDESTADDRREQ;
398 cleanup:
399	if (resp != NULL)
400		free(resp);
401	return (-1);
402}
403
404static int
405get_ns(res_state statp, const char *zname, ns_class class, int opts,
406      rrset_ns *nsrrsp)
407{
408	u_char *resp;
409	ns_msg msg;
410	int n;
411
412	resp = malloc(NS_MAXMSG);
413	if (resp == NULL)
414		return (-1);
415
416	/* Go and get the NS RRs for this zone. */
417	n = do_query(statp, zname, class, ns_t_ns, resp, &msg);
418	if (n != 0) {
419		DPRINTF(("get_ns: do_query('%s', %s) failed (%d)",
420			 zname, p_class(class), n));
421		free(resp);
422		return (-1);
423	}
424
425	/* Remember the NS RRs and associated A RRs that came back. */
426	if (save_ns(statp, &msg, ns_s_an, zname, class, opts, nsrrsp) < 0) {
427		DPRINTF(("get_ns save_ns('%s', %s) failed",
428			 zname, p_class(class)));
429		free(resp);
430		return (-1);
431	}
432
433	free(resp);
434	return (0);
435}
436
437static int
438get_glue(res_state statp, ns_class class, int opts, rrset_ns *nsrrsp) {
439	rr_ns *nsrr, *nsrr_n;
440	u_char *resp;
441
442	resp = malloc(NS_MAXMSG);
443	if (resp == NULL)
444		return(-1);
445
446	/* Go and get the A RRs for each empty NS RR on our list. */
447	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
448		ns_msg msg;
449		int n;
450
451		nsrr_n = NEXT(nsrr, link);
452
453		if ((nsrr->flags & RR_NS_HAVE_V4) == 0) {
454			n = do_query(statp, nsrr->name, class, ns_t_a,
455				     resp, &msg);
456			if (n < 0) {
457				DPRINTF(
458				       ("get_glue: do_query('%s', %s') failed",
459					nsrr->name, p_class(class)));
460				goto cleanup;
461			}
462			if (n > 0) {
463				DPRINTF((
464			"get_glue: do_query('%s', %s') CNAME or DNAME found",
465					 nsrr->name, p_class(class)));
466			}
467			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
468				   opts, nsrr) < 0) {
469				DPRINTF(("get_glue: save_r('%s', %s) failed",
470					 nsrr->name, p_class(class)));
471				goto cleanup;
472			}
473		}
474
475		if ((nsrr->flags & RR_NS_HAVE_V6) == 0) {
476			n = do_query(statp, nsrr->name, class, ns_t_aaaa,
477				     resp, &msg);
478			if (n < 0) {
479				DPRINTF(
480				       ("get_glue: do_query('%s', %s') failed",
481					nsrr->name, p_class(class)));
482				goto cleanup;
483			}
484			if (n > 0) {
485				DPRINTF((
486			"get_glue: do_query('%s', %s') CNAME or DNAME found",
487					 nsrr->name, p_class(class)));
488			}
489			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
490				   opts, nsrr) < 0) {
491				DPRINTF(("get_glue: save_r('%s', %s) failed",
492					 nsrr->name, p_class(class)));
493				goto cleanup;
494			}
495		}
496
497		/* If it's still empty, it's just chaff. */
498		if (EMPTY(nsrr->addrs)) {
499			DPRINTF(("get_glue: removing empty '%s' NS",
500				 nsrr->name));
501			free_nsrr(nsrrsp, nsrr);
502		}
503	}
504	free(resp);
505	return (0);
506
507 cleanup:
508	free(resp);
509	return (-1);
510}
511
512static int
513save_ns(res_state statp, ns_msg *msg, ns_sect sect,
514	const char *owner, ns_class class, int opts,
515	rrset_ns *nsrrsp)
516{
517	int i;
518
519	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
520		char tname[MAXDNAME];
521		const u_char *rdata;
522		rr_ns *nsrr;
523		ns_rr rr;
524
525		if (ns_parserr(msg, sect, i, &rr) < 0) {
526			DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
527				 p_section(sect, ns_o_query), i));
528			return (-1);
529		}
530		if (ns_rr_type(rr) != ns_t_ns ||
531		    ns_rr_class(rr) != class ||
532		    ns_samename(ns_rr_name(rr), owner) != 1)
533			continue;
534		nsrr = find_ns(nsrrsp, ns_rr_name(rr));
535		if (nsrr == NULL) {
536			nsrr = malloc(sizeof *nsrr);
537			if (nsrr == NULL) {
538				DPRINTF(("save_ns: malloc failed"));
539				return (-1);
540			}
541			rdata = ns_rr_rdata(rr);
542			if (ns_name_uncompress(ns_msg_base(*msg),
543					       ns_msg_end(*msg), rdata,
544					       tname, sizeof tname) < 0) {
545				DPRINTF(("save_ns: ns_name_uncompress failed")
546					);
547				free(nsrr);
548				return (-1);
549			}
550			nsrr->name = strdup(tname);
551			if (nsrr->name == NULL) {
552				DPRINTF(("save_ns: strdup failed"));
553				free(nsrr);
554				return (-1);
555			}
556			INIT_LINK(nsrr, link);
557			INIT_LIST(nsrr->addrs);
558			nsrr->flags = 0;
559			APPEND(*nsrrsp, nsrr, link);
560		}
561		if (save_a(statp, msg, ns_s_ar,
562			   nsrr->name, class, opts, nsrr) < 0) {
563			DPRINTF(("save_ns: save_r('%s', %s) failed",
564				 nsrr->name, p_class(class)));
565			return (-1);
566		}
567	}
568	return (0);
569}
570
571static int
572save_a(res_state statp, ns_msg *msg, ns_sect sect,
573       const char *owner, ns_class class, int opts,
574       rr_ns *nsrr)
575{
576	int i;
577
578	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
579		ns_rr rr;
580		rr_a *arr;
581
582		if (ns_parserr(msg, sect, i, &rr) < 0) {
583			DPRINTF(("save_a: ns_parserr(%s, %d) failed",
584				 p_section(sect, ns_o_query), i));
585			return (-1);
586		}
587		if ((ns_rr_type(rr) != ns_t_a &&
588		     ns_rr_type(rr) != ns_t_aaaa) ||
589		    ns_rr_class(rr) != class ||
590		    ns_samename(ns_rr_name(rr), owner) != 1 ||
591		    ns_rr_rdlen(rr) != NS_INADDRSZ)
592			continue;
593		if ((opts & RES_IPV6ONLY) != 0 && ns_rr_type(rr) != ns_t_aaaa)
594			continue;
595		if ((opts & RES_IPV4ONLY) != 0 && ns_rr_type(rr) != ns_t_a)
596			continue;
597		arr = malloc(sizeof *arr);
598		if (arr == NULL) {
599			DPRINTF(("save_a: malloc failed"));
600			return (-1);
601		}
602		INIT_LINK(arr, link);
603		memset(&arr->addr, 0, sizeof(arr->addr));
604		switch (ns_rr_type(rr)) {
605		case ns_t_a:
606			arr->addr.sin.sin_family = AF_INET;
607#ifdef HAVE_SA_LEN
608			arr->addr.sin.sin_len = sizeof(arr->addr.sin);
609#endif
610			memcpy(&arr->addr.sin.sin_addr, ns_rr_rdata(rr),
611			       NS_INADDRSZ);
612			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
613			nsrr->flags |= RR_NS_HAVE_V4;
614			break;
615		case ns_t_aaaa:
616			arr->addr.sin6.sin6_family = AF_INET6;
617#ifdef HAVE_SA_LEN
618			arr->addr.sin6.sin6_len = sizeof(arr->addr.sin6);
619#endif
620			memcpy(&arr->addr.sin6.sin6_addr, ns_rr_rdata(rr), 16);
621			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
622			nsrr->flags |= RR_NS_HAVE_V6;
623			break;
624		default:
625			abort();
626		}
627		APPEND(nsrr->addrs, arr, link);
628	}
629	return (0);
630}
631
632static void
633free_nsrrset(rrset_ns *nsrrsp) {
634	rr_ns *nsrr;
635
636	while ((nsrr = HEAD(*nsrrsp)) != NULL)
637		free_nsrr(nsrrsp, nsrr);
638}
639
640static void
641free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
642	rr_a *arr;
643	char *tmp;
644
645	while ((arr = HEAD(nsrr->addrs)) != NULL) {
646		UNLINK(nsrr->addrs, arr, link);
647		free(arr);
648	}
649	DE_CONST(nsrr->name, tmp);
650	free(tmp);
651	UNLINK(*nsrrsp, nsrr, link);
652	free(nsrr);
653}
654
655static rr_ns *
656find_ns(rrset_ns *nsrrsp, const char *dname) {
657	rr_ns *nsrr;
658
659	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = NEXT(nsrr, link))
660		if (ns_samename(nsrr->name, dname) == 1)
661			return (nsrr);
662	return (NULL);
663}
664
665static int
666do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
667	 u_char *resp, ns_msg *msg)
668{
669	u_char req[NS_PACKETSZ];
670	int i, n;
671
672	n = res_nmkquery(statp, ns_o_query, dname, class, qtype,
673			 NULL, 0, NULL, req, NS_PACKETSZ);
674	if (n < 0) {
675		DPRINTF(("do_query: res_nmkquery failed"));
676		return (-1);
677	}
678	n = res_nsend(statp, req, n, resp, NS_MAXMSG);
679	if (n < 0) {
680		DPRINTF(("do_query: res_nsend failed"));
681		return (-1);
682	}
683	if (n == 0) {
684		DPRINTF(("do_query: res_nsend returned 0"));
685		errno = EMSGSIZE;
686		return (-1);
687	}
688	if (ns_initparse(resp, n, msg) < 0) {
689		DPRINTF(("do_query: ns_initparse failed"));
690		return (-1);
691	}
692	n = 0;
693	for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
694		ns_rr rr;
695
696		if (ns_parserr(msg, ns_s_an, i, &rr) < 0) {
697			DPRINTF(("do_query: ns_parserr failed"));
698			return (-1);
699		}
700		n += (ns_rr_class(rr) == class &&
701		      (ns_rr_type(rr) == ns_t_cname ||
702		       ns_rr_type(rr) == ns_t_dname));
703	}
704	return (n);
705}
706
707static void
708res_dprintf(const char *fmt, ...) {
709	va_list ap;
710
711	va_start(ap, fmt);
712	fputs(";; res_findzonecut: ", stderr);
713	vfprintf(stderr, fmt, ap);
714	fputc('\n', stderr);
715	va_end(ap);
716}
717
718/*! \file */
719