1/*	$NetBSD$	*/
2
3#if !defined(lint) && !defined(SABER)
4static const char rcsid[] = "Id: res_findzonecut.c,v 1.10 2005/10/11 00:10:16 marka Exp";
5#endif /* not lint */
6
7/*
8 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
9 * Copyright (c) 1999 by Internet Software Consortium.
10 *
11 * Permission to use, copy, modify, and distribute this software for any
12 * purpose with or without fee is hereby granted, provided that the above
13 * copyright notice and this permission notice appear in all copies.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
16 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
17 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
18 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
19 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
20 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
21 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 */
23
24/* Import. */
25
26#include "port_before.h"
27
28#include <sys/param.h>
29#include <sys/socket.h>
30#include <sys/time.h>
31
32#include <netinet/in.h>
33#include <arpa/inet.h>
34#include <arpa/nameser.h>
35
36#include <errno.h>
37#include <limits.h>
38#include <netdb.h>
39#include <stdarg.h>
40#include <stdio.h>
41#include <stdlib.h>
42#include <string.h>
43
44#include <isc/list.h>
45
46#include "port_after.h"
47
48#include <resolv.h>
49
50/* Data structures. */
51
52typedef struct rr_a {
53	LINK(struct rr_a)	link;
54	union res_sockaddr_union addr;
55} rr_a;
56typedef LIST(rr_a) rrset_a;
57
58typedef struct rr_ns {
59	LINK(struct rr_ns)	link;
60	const char *		name;
61	unsigned int		flags;
62	rrset_a			addrs;
63} rr_ns;
64typedef LIST(rr_ns) rrset_ns;
65
66#define	RR_NS_HAVE_V4		0x01
67#define	RR_NS_HAVE_V6		0x02
68
69/* Forward. */
70
71static int	satisfy(res_state, const char *, rrset_ns *,
72			union res_sockaddr_union *, int);
73static int	add_addrs(res_state, rr_ns *,
74			  union res_sockaddr_union *, int);
75static int	get_soa(res_state, const char *, ns_class, int,
76			char *, size_t, char *, size_t,
77			rrset_ns *);
78static int	get_ns(res_state, const char *, ns_class, int, rrset_ns *);
79static int	get_glue(res_state, ns_class, int, rrset_ns *);
80static int	save_ns(res_state, ns_msg *, ns_sect,
81			const char *, ns_class, int, rrset_ns *);
82static int	save_a(res_state, ns_msg *, ns_sect,
83		       const char *, ns_class, int, rr_ns *);
84static void	free_nsrrset(rrset_ns *);
85static void	free_nsrr(rrset_ns *, rr_ns *);
86static rr_ns *	find_ns(rrset_ns *, const char *);
87static int	do_query(res_state, const char *, ns_class, ns_type,
88			 u_char *, ns_msg *);
89static void	res_dprintf(const char *, ...) ISC_FORMAT_PRINTF(1, 2);
90
91/* Macros. */
92
93#define DPRINTF(x) do {\
94		int save_errno = errno; \
95		if ((statp->options & RES_DEBUG) != 0U) res_dprintf x; \
96		errno = save_errno; \
97	} while (0)
98
99/* Public. */
100
101/*%
102 *	find enclosing zone for a <dname,class>, and some server addresses
103 *
104 * parameters:
105 *\li	res - resolver context to work within (is modified)
106 *\li	dname - domain name whose enclosing zone is desired
107 *\li	class - class of dname (and its enclosing zone)
108 *\li	zname - found zone name
109 *\li	zsize - allocated size of zname
110 *\li	addrs - found server addresses
111 *\li	naddrs - max number of addrs
112 *
113 * return values:
114 *\li	< 0 - an error occurred (check errno)
115 *\li	= 0 - zname is now valid, but addrs[] wasn't changed
116 *\li	> 0 - zname is now valid, and return value is number of addrs[] found
117 *
118 * notes:
119 *\li	this function calls res_nsend() which means it depends on correctly
120 *	functioning recursive nameservers (usually defined in /etc/resolv.conf
121 *	or its local equivilent).
122 *
123 *\li	we start by asking for an SOA<dname,class>.  if we get one as an
124 *	answer, that just means <dname,class> is a zone top, which is fine.
125 *	more than likely we'll be told to go pound sand, in the form of a
126 *	negative answer.
127 *
128 *\li	note that we are not prepared to deal with referrals since that would
129 *	only come from authority servers and our correctly functioning local
130 *	recursive server would have followed the referral and got us something
131 *	more definite.
132 *
133 *\li	if the authority section contains an SOA, this SOA should also be the
134 *	closest enclosing zone, since any intermediary zone cuts would've been
135 *	returned as referrals and dealt with by our correctly functioning local
136 *	recursive name server.  but an SOA in the authority section should NOT
137 *	match our dname (since that would have been returned in the answer
138 *	section).  an authority section SOA has to be "above" our dname.
139 *
140 *\li	however, since authority section SOA's were once optional, it's
141 *	possible that we'll have to go hunting for the enclosing SOA by
142 *	ripping labels off the front of our dname -- this is known as "doing
143 *	it the hard way."
144 *
145 *\li	ultimately we want some server addresses, which are ideally the ones
146 *	pertaining to the SOA.MNAME, but only if there is a matching NS RR.
147 *	so the second phase (after we find an SOA) is to go looking for the
148 *	NS RRset for that SOA's zone.
149 *
150 *\li	no answer section processed by this code is allowed to contain CNAME
151 *	or DNAME RR's.  for the SOA query this means we strip a label and
152 *	keep going.  for the NS and A queries this means we just give up.
153 */
154
155int
156res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
157		char *zname, size_t zsize, struct in_addr *addrs, int naddrs)
158{
159	int result, i;
160	union res_sockaddr_union *u;
161
162
163	opts |= RES_IPV4ONLY;
164	opts &= ~RES_IPV6ONLY;
165
166	u = calloc(naddrs, sizeof(*u));
167	if (u == NULL)
168		return(-1);
169
170	result = res_findzonecut2(statp, dname, class, opts, zname, zsize,
171				  u, naddrs);
172
173	for (i = 0; i < result; i++) {
174		addrs[i] = u[i].sin.sin_addr;
175	}
176	free(u);
177	return (result);
178}
179
180int
181res_findzonecut2(res_state statp, const char *dname, ns_class class, int opts,
182		 char *zname, size_t zsize, union res_sockaddr_union *addrs,
183		 int naddrs)
184{
185	char mname[NS_MAXDNAME];
186	u_long save_pfcode;
187	rrset_ns nsrrs;
188	int n;
189
190	DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
191		 dname, p_class(class), (long)zsize, naddrs));
192	save_pfcode = statp->pfcode;
193	statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
194			 RES_PRF_QUES | RES_PRF_ANS |
195			 RES_PRF_AUTH | RES_PRF_ADD;
196	INIT_LIST(nsrrs);
197
198	DPRINTF(("get the soa, and see if it has enough glue"));
199	if ((n = get_soa(statp, dname, class, opts, zname, zsize,
200			 mname, sizeof mname, &nsrrs)) < 0 ||
201	    ((opts & RES_EXHAUSTIVE) == 0 &&
202	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
203		goto done;
204
205	DPRINTF(("get the ns rrset and see if it has enough glue"));
206	if ((n = get_ns(statp, zname, class, opts, &nsrrs)) < 0 ||
207	    ((opts & RES_EXHAUSTIVE) == 0 &&
208	     (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
209		goto done;
210
211	DPRINTF(("get the missing glue and see if it's finally enough"));
212	if ((n = get_glue(statp, class, opts, &nsrrs)) >= 0)
213		n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
214
215 done:
216	DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
217	free_nsrrset(&nsrrs);
218	statp->pfcode = save_pfcode;
219	return (n);
220}
221
222/* Private. */
223
224static int
225satisfy(res_state statp, const char *mname, rrset_ns *nsrrsp,
226	union res_sockaddr_union *addrs, int naddrs)
227{
228	rr_ns *nsrr;
229	int n, x;
230
231	n = 0;
232	nsrr = find_ns(nsrrsp, mname);
233	if (nsrr != NULL) {
234		x = add_addrs(statp, nsrr, addrs, naddrs);
235		addrs += x;
236		naddrs -= x;
237		n += x;
238	}
239	for (nsrr = HEAD(*nsrrsp);
240	     nsrr != NULL && naddrs > 0;
241	     nsrr = NEXT(nsrr, link))
242		if (ns_samename(nsrr->name, mname) != 1) {
243			x = add_addrs(statp, nsrr, addrs, naddrs);
244			addrs += x;
245			naddrs -= x;
246			n += x;
247		}
248	DPRINTF(("satisfy(%s): %d", mname, n));
249	return (n);
250}
251
252static int
253add_addrs(res_state statp, rr_ns *nsrr,
254	  union res_sockaddr_union *addrs, int naddrs)
255{
256	rr_a *arr;
257	int n = 0;
258
259	for (arr = HEAD(nsrr->addrs); arr != NULL; arr = NEXT(arr, link)) {
260		if (naddrs <= 0)
261			return (0);
262		*addrs++ = arr->addr;
263		naddrs--;
264		n++;
265	}
266	DPRINTF(("add_addrs: %d", n));
267	return (n);
268}
269
270static int
271get_soa(res_state statp, const char *dname, ns_class class, int opts,
272	char *zname, size_t zsize, char *mname, size_t msize,
273	rrset_ns *nsrrsp)
274{
275	char tname[NS_MAXDNAME];
276	u_char *resp = NULL;
277	int n, i, ancount, nscount;
278	ns_sect sect;
279	ns_msg msg;
280	u_int rcode;
281
282	/*
283	 * Find closest enclosing SOA, even if it's for the root zone.
284	 */
285
286	/* First canonicalize dname (exactly one unescaped trailing "."). */
287	if (ns_makecanon(dname, tname, sizeof tname) < 0)
288		goto cleanup;
289	dname = tname;
290
291	resp = malloc(NS_MAXMSG);
292	if (resp == NULL)
293		goto cleanup;
294
295	/* Now grovel the subdomains, hunting for an SOA answer or auth. */
296	for (;;) {
297		/* Leading or inter-label '.' are skipped here. */
298		while (*dname == '.')
299			dname++;
300
301		/* Is there an SOA? */
302		n = do_query(statp, dname, class, ns_t_soa, resp, &msg);
303		if (n < 0) {
304			DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
305				 dname, p_class(class), n));
306			goto cleanup;
307		}
308		if (n > 0) {
309			DPRINTF(("get_soa: CNAME or DNAME found"));
310			sect = ns_s_max, n = 0;
311		} else {
312			rcode = ns_msg_getflag(msg, ns_f_rcode);
313			ancount = ns_msg_count(msg, ns_s_an);
314			nscount = ns_msg_count(msg, ns_s_ns);
315			if (ancount > 0 && rcode == ns_r_noerror)
316				sect = ns_s_an, n = ancount;
317			else if (nscount > 0)
318				sect = ns_s_ns, n = nscount;
319			else
320				sect = ns_s_max, n = 0;
321		}
322		for (i = 0; i < n; i++) {
323			const char *t;
324			const u_char *rdata;
325			ns_rr rr;
326
327			if (ns_parserr(&msg, sect, i, &rr) < 0) {
328				DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
329					 p_section(sect, ns_o_query), i));
330				goto cleanup;
331			}
332			if (ns_rr_type(rr) == ns_t_cname ||
333			    ns_rr_type(rr) == ns_t_dname)
334				break;
335			if (ns_rr_type(rr) != ns_t_soa ||
336			    ns_rr_class(rr) != class)
337				continue;
338			t = ns_rr_name(rr);
339			switch (sect) {
340			case ns_s_an:
341				if (ns_samedomain(dname, t) == 0) {
342					DPRINTF(
343				    ("get_soa: ns_samedomain('%s', '%s') == 0",
344						dname, t)
345						);
346					errno = EPROTOTYPE;
347					goto cleanup;
348				}
349				break;
350			case ns_s_ns:
351				if (ns_samename(dname, t) == 1 ||
352				    ns_samedomain(dname, t) == 0) {
353					DPRINTF(
354		       ("get_soa: ns_samename() || !ns_samedomain('%s', '%s')",
355						dname, t)
356						);
357					errno = EPROTOTYPE;
358					goto cleanup;
359				}
360				break;
361			default:
362				abort();
363			}
364			if (strlen(t) + 1 > zsize) {
365				DPRINTF(("get_soa: zname(%lu) too small (%lu)",
366					 (unsigned long)zsize,
367					 (unsigned long)strlen(t) + 1));
368				errno = EMSGSIZE;
369				goto cleanup;
370			}
371			strcpy(zname, t);
372			rdata = ns_rr_rdata(rr);
373			if (ns_name_uncompress(resp, ns_msg_end(msg), rdata,
374					       mname, msize) < 0) {
375				DPRINTF(("get_soa: ns_name_uncompress failed")
376					);
377				goto cleanup;
378			}
379			if (save_ns(statp, &msg, ns_s_ns,
380				    zname, class, opts, nsrrsp) < 0) {
381				DPRINTF(("get_soa: save_ns failed"));
382				goto cleanup;
383			}
384			free(resp);
385			return (0);
386		}
387
388		/* If we're out of labels, then not even "." has an SOA! */
389		if (*dname == '\0')
390			break;
391
392		/* Find label-terminating "."; top of loop will skip it. */
393		while (*dname != '.') {
394			if (*dname == '\\')
395				if (*++dname == '\0') {
396					errno = EMSGSIZE;
397					goto cleanup;
398				}
399			dname++;
400		}
401	}
402	DPRINTF(("get_soa: out of labels"));
403	errno = EDESTADDRREQ;
404 cleanup:
405	if (resp != NULL)
406		free(resp);
407	return (-1);
408}
409
410static int
411get_ns(res_state statp, const char *zname, ns_class class, int opts,
412      rrset_ns *nsrrsp)
413{
414	u_char *resp;
415	ns_msg msg;
416	int n;
417
418	resp = malloc(NS_MAXMSG);
419	if (resp == NULL)
420		return (-1);
421
422	/* Go and get the NS RRs for this zone. */
423	n = do_query(statp, zname, class, ns_t_ns, resp, &msg);
424	if (n != 0) {
425		DPRINTF(("get_ns: do_query('%s', %s) failed (%d)",
426			 zname, p_class(class), n));
427		free(resp);
428		return (-1);
429	}
430
431	/* Remember the NS RRs and associated A RRs that came back. */
432	if (save_ns(statp, &msg, ns_s_an, zname, class, opts, nsrrsp) < 0) {
433		DPRINTF(("get_ns save_ns('%s', %s) failed",
434			 zname, p_class(class)));
435		free(resp);
436		return (-1);
437	}
438
439	free(resp);
440	return (0);
441}
442
443static int
444get_glue(res_state statp, ns_class class, int opts, rrset_ns *nsrrsp) {
445	rr_ns *nsrr, *nsrr_n;
446	u_char *resp;
447
448	resp = malloc(NS_MAXMSG);
449	if (resp == NULL)
450		return(-1);
451
452	/* Go and get the A RRs for each empty NS RR on our list. */
453	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
454		ns_msg msg;
455		int n;
456
457		nsrr_n = NEXT(nsrr, link);
458
459		if ((nsrr->flags & RR_NS_HAVE_V4) == 0) {
460			n = do_query(statp, nsrr->name, class, ns_t_a,
461				     resp, &msg);
462			if (n < 0) {
463				DPRINTF(
464				       ("get_glue: do_query('%s', %s') failed",
465					nsrr->name, p_class(class)));
466				goto cleanup;
467			}
468			if (n > 0) {
469				DPRINTF((
470			"get_glue: do_query('%s', %s') CNAME or DNAME found",
471					 nsrr->name, p_class(class)));
472			}
473			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
474				   opts, nsrr) < 0) {
475				DPRINTF(("get_glue: save_r('%s', %s) failed",
476					 nsrr->name, p_class(class)));
477				goto cleanup;
478			}
479		}
480
481		if ((nsrr->flags & RR_NS_HAVE_V6) == 0) {
482			n = do_query(statp, nsrr->name, class, ns_t_aaaa,
483				     resp, &msg);
484			if (n < 0) {
485				DPRINTF(
486				       ("get_glue: do_query('%s', %s') failed",
487					nsrr->name, p_class(class)));
488				goto cleanup;
489			}
490			if (n > 0) {
491				DPRINTF((
492			"get_glue: do_query('%s', %s') CNAME or DNAME found",
493					 nsrr->name, p_class(class)));
494			}
495			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
496				   opts, nsrr) < 0) {
497				DPRINTF(("get_glue: save_r('%s', %s) failed",
498					 nsrr->name, p_class(class)));
499				goto cleanup;
500			}
501		}
502
503		/* If it's still empty, it's just chaff. */
504		if (EMPTY(nsrr->addrs)) {
505			DPRINTF(("get_glue: removing empty '%s' NS",
506				 nsrr->name));
507			free_nsrr(nsrrsp, nsrr);
508		}
509	}
510	free(resp);
511	return (0);
512
513 cleanup:
514	free(resp);
515	return (-1);
516}
517
518static int
519save_ns(res_state statp, ns_msg *msg, ns_sect sect,
520	const char *owner, ns_class class, int opts,
521	rrset_ns *nsrrsp)
522{
523	int i;
524
525	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
526		char tname[MAXDNAME];
527		const u_char *rdata;
528		rr_ns *nsrr;
529		ns_rr rr;
530
531		if (ns_parserr(msg, sect, i, &rr) < 0) {
532			DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
533				 p_section(sect, ns_o_query), i));
534			return (-1);
535		}
536		if (ns_rr_type(rr) != ns_t_ns ||
537		    ns_rr_class(rr) != class ||
538		    ns_samename(ns_rr_name(rr), owner) != 1)
539			continue;
540		nsrr = find_ns(nsrrsp, ns_rr_name(rr));
541		if (nsrr == NULL) {
542			nsrr = malloc(sizeof *nsrr);
543			if (nsrr == NULL) {
544				DPRINTF(("save_ns: malloc failed"));
545				return (-1);
546			}
547			rdata = ns_rr_rdata(rr);
548			if (ns_name_uncompress(ns_msg_base(*msg),
549					       ns_msg_end(*msg), rdata,
550					       tname, sizeof tname) < 0) {
551				DPRINTF(("save_ns: ns_name_uncompress failed")
552					);
553				free(nsrr);
554				return (-1);
555			}
556			nsrr->name = strdup(tname);
557			if (nsrr->name == NULL) {
558				DPRINTF(("save_ns: strdup failed"));
559				free(nsrr);
560				return (-1);
561			}
562			INIT_LINK(nsrr, link);
563			INIT_LIST(nsrr->addrs);
564			nsrr->flags = 0;
565			APPEND(*nsrrsp, nsrr, link);
566		}
567		if (save_a(statp, msg, ns_s_ar,
568			   nsrr->name, class, opts, nsrr) < 0) {
569			DPRINTF(("save_ns: save_r('%s', %s) failed",
570				 nsrr->name, p_class(class)));
571			return (-1);
572		}
573	}
574	return (0);
575}
576
577static int
578save_a(res_state statp, ns_msg *msg, ns_sect sect,
579       const char *owner, ns_class class, int opts,
580       rr_ns *nsrr)
581{
582	int i;
583
584	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
585		ns_rr rr;
586		rr_a *arr;
587
588		if (ns_parserr(msg, sect, i, &rr) < 0) {
589			DPRINTF(("save_a: ns_parserr(%s, %d) failed",
590				 p_section(sect, ns_o_query), i));
591			return (-1);
592		}
593		if ((ns_rr_type(rr) != ns_t_a &&
594		     ns_rr_type(rr) != ns_t_aaaa) ||
595		    ns_rr_class(rr) != class ||
596		    ns_samename(ns_rr_name(rr), owner) != 1 ||
597		    ns_rr_rdlen(rr) != NS_INADDRSZ)
598			continue;
599		if ((opts & RES_IPV6ONLY) != 0 && ns_rr_type(rr) != ns_t_aaaa)
600			continue;
601		if ((opts & RES_IPV4ONLY) != 0 && ns_rr_type(rr) != ns_t_a)
602			continue;
603		arr = malloc(sizeof *arr);
604		if (arr == NULL) {
605			DPRINTF(("save_a: malloc failed"));
606			return (-1);
607		}
608		INIT_LINK(arr, link);
609		memset(&arr->addr, 0, sizeof(arr->addr));
610		switch (ns_rr_type(rr)) {
611		case ns_t_a:
612			arr->addr.sin.sin_family = AF_INET;
613#ifdef HAVE_SA_LEN
614			arr->addr.sin.sin_len = sizeof(arr->addr.sin);
615#endif
616			memcpy(&arr->addr.sin.sin_addr, ns_rr_rdata(rr),
617			       NS_INADDRSZ);
618			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
619			nsrr->flags |= RR_NS_HAVE_V4;
620			break;
621		case ns_t_aaaa:
622			arr->addr.sin6.sin6_family = AF_INET6;
623#ifdef HAVE_SA_LEN
624			arr->addr.sin6.sin6_len = sizeof(arr->addr.sin6);
625#endif
626			memcpy(&arr->addr.sin6.sin6_addr, ns_rr_rdata(rr), 16);
627			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
628			nsrr->flags |= RR_NS_HAVE_V6;
629			break;
630		default:
631			abort();
632		}
633		APPEND(nsrr->addrs, arr, link);
634	}
635	return (0);
636}
637
638static void
639free_nsrrset(rrset_ns *nsrrsp) {
640	rr_ns *nsrr;
641
642	while ((nsrr = HEAD(*nsrrsp)) != NULL)
643		free_nsrr(nsrrsp, nsrr);
644}
645
646static void
647free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
648	rr_a *arr;
649	char *tmp;
650
651	while ((arr = HEAD(nsrr->addrs)) != NULL) {
652		UNLINK(nsrr->addrs, arr, link);
653		free(arr);
654	}
655	DE_CONST(nsrr->name, tmp);
656	free(tmp);
657	UNLINK(*nsrrsp, nsrr, link);
658	free(nsrr);
659}
660
661static rr_ns *
662find_ns(rrset_ns *nsrrsp, const char *dname) {
663	rr_ns *nsrr;
664
665	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = NEXT(nsrr, link))
666		if (ns_samename(nsrr->name, dname) == 1)
667			return (nsrr);
668	return (NULL);
669}
670
671static int
672do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
673	 u_char *resp, ns_msg *msg)
674{
675	u_char req[NS_PACKETSZ];
676	int i, n;
677
678	n = res_nmkquery(statp, ns_o_query, dname, class, qtype,
679			 NULL, 0, NULL, req, NS_PACKETSZ);
680	if (n < 0) {
681		DPRINTF(("do_query: res_nmkquery failed"));
682		return (-1);
683	}
684	n = res_nsend(statp, req, n, resp, NS_MAXMSG);
685	if (n < 0) {
686		DPRINTF(("do_query: res_nsend failed"));
687		return (-1);
688	}
689	if (n == 0) {
690		DPRINTF(("do_query: res_nsend returned 0"));
691		errno = EMSGSIZE;
692		return (-1);
693	}
694	if (ns_initparse(resp, n, msg) < 0) {
695		DPRINTF(("do_query: ns_initparse failed"));
696		return (-1);
697	}
698	n = 0;
699	for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
700		ns_rr rr;
701
702		if (ns_parserr(msg, ns_s_an, i, &rr) < 0) {
703			DPRINTF(("do_query: ns_parserr failed"));
704			return (-1);
705		}
706		n += (ns_rr_class(rr) == class &&
707		      (ns_rr_type(rr) == ns_t_cname ||
708		       ns_rr_type(rr) == ns_t_dname));
709	}
710	return (n);
711}
712
713static void
714res_dprintf(const char *fmt, ...) {
715	va_list ap;
716
717	va_start(ap, fmt);
718	fputs(";; res_findzonecut: ", stderr);
719	vfprintf(stderr, fmt, ap);
720	fputc('\n', stderr);
721	va_end(ap);
722}
723
724/*! \file */
725