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 $";
3#endif /* not lint */
4
5/*-
6 * SPDX-License-Identifier: ISC
7 *
8 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
9 * Copyright (c) 1999 by Internet Software Consortium.
10 *
11 * Permission to use, copy, modify, and distribute this software for any
12 * purpose with or without fee is hereby granted, provided that the above
13 * copyright notice and this permission notice appear in all copies.
14 *
15 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
16 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
17 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
18 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
19 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
20 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
21 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
22 */
23
24#include <sys/cdefs.h>
25__FBSDID("$FreeBSD$");
26
27/* Import. */
28
29#include "port_before.h"
30
31#include <sys/param.h>
32#include <sys/socket.h>
33#include <sys/time.h>
34
35#include <netinet/in.h>
36#include <arpa/inet.h>
37#include <arpa/nameser.h>
38
39#include <errno.h>
40#include <limits.h>
41#include <netdb.h>
42#include <stdarg.h>
43#include <stdio.h>
44#include <stdlib.h>
45#include <string.h>
46
47#include <isc/list.h>
48
49#include "port_after.h"
50
51#include <resolv.h>
52
53/* Data structures. */
54
55typedef struct rr_a {
56	LINK(struct rr_a)	link;
57	union res_sockaddr_union addr;
58} rr_a;
59typedef LIST(rr_a) rrset_a;
60
61typedef struct rr_ns {
62	LINK(struct rr_ns)	link;
63	const char *		name;
64	unsigned int		flags;
65	rrset_a			addrs;
66} rr_ns;
67typedef LIST(rr_ns) rrset_ns;
68
69#define	RR_NS_HAVE_V4		0x01
70#define	RR_NS_HAVE_V6		0x02
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 *);
92static void	res_dprintf(const char *, ...) ISC_FORMAT_PRINTF(1, 2);
93
94/* Macros. */
95
96#define DPRINTF(x) do {\
97		int save_errno = errno; \
98		if ((statp->options & RES_DEBUG) != 0U) res_dprintf x; \
99		errno = save_errno; \
100	} while (0)
101
102/* Public. */
103
104/*%
105 *	find enclosing zone for a <dname,class>, and some server addresses
106 *
107 * parameters:
108 *\li	res - resolver context to work within (is modified)
109 *\li	dname - domain name whose enclosing zone is desired
110 *\li	class - class of dname (and its enclosing zone)
111 *\li	zname - found zone name
112 *\li	zsize - allocated size of zname
113 *\li	addrs - found server addresses
114 *\li	naddrs - max number of addrs
115 *
116 * return values:
117 *\li	< 0 - an error occurred (check errno)
118 *\li	= 0 - zname is now valid, but addrs[] wasn't changed
119 *\li	> 0 - zname is now valid, and return value is number of addrs[] found
120 *
121 * notes:
122 *\li	this function calls res_nsend() which means it depends on correctly
123 *	functioning recursive nameservers (usually defined in /etc/resolv.conf
124 *	or its local equivalent).
125 *
126 *\li	we start by asking for an SOA<dname,class>.  if we get one as an
127 *	answer, that just means <dname,class> is a zone top, which is fine.
128 *	more than likely we'll be told to go pound sand, in the form of a
129 *	negative answer.
130 *
131 *\li	note that we are not prepared to deal with referrals since that would
132 *	only come from authority servers and our correctly functioning local
133 *	recursive server would have followed the referral and got us something
134 *	more definite.
135 *
136 *\li	if the authority section contains an SOA, this SOA should also be the
137 *	closest enclosing zone, since any intermediary zone cuts would've been
138 *	returned as referrals and dealt with by our correctly functioning local
139 *	recursive name server.  but an SOA in the authority section should NOT
140 *	match our dname (since that would have been returned in the answer
141 *	section).  an authority section SOA has to be "above" our dname.
142 *
143 *\li	however, since authority section SOA's were once optional, it's
144 *	possible that we'll have to go hunting for the enclosing SOA by
145 *	ripping labels off the front of our dname -- this is known as "doing
146 *	it the hard way."
147 *
148 *\li	ultimately we want some server addresses, which are ideally the ones
149 *	pertaining to the SOA.MNAME, but only if there is a matching NS RR.
150 *	so the second phase (after we find an SOA) is to go looking for the
151 *	NS RRset for that SOA's zone.
152 *
153 *\li	no answer section processed by this code is allowed to contain CNAME
154 *	or DNAME RR's.  for the SOA query this means we strip a label and
155 *	keep going.  for the NS and A queries this means we just give up.
156 */
157
158#ifndef _LIBC
159int
160res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
161		char *zname, size_t zsize, struct in_addr *addrs, int naddrs)
162{
163	int result, i;
164	union res_sockaddr_union *u;
165
166
167	opts |= RES_IPV4ONLY;
168	opts &= ~RES_IPV6ONLY;
169
170	u = calloc(naddrs, sizeof(*u));
171	if (u == NULL)
172		return(-1);
173
174	result = res_findzonecut2(statp, dname, class, opts, zname, zsize,
175				  u, naddrs);
176
177	for (i = 0; i < result; i++) {
178		addrs[i] = u[i].sin.sin_addr;
179	}
180	free(u);
181	return (result);
182}
183#endif
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 = NULL;
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		goto cleanup;
294	dname = tname;
295
296	resp = malloc(NS_MAXMSG);
297	if (resp == NULL)
298		goto cleanup;
299
300	/* Now grovel the subdomains, hunting for an SOA answer or auth. */
301	for (;;) {
302		/* Leading or inter-label '.' are skipped here. */
303		while (*dname == '.')
304			dname++;
305
306		/* Is there an SOA? */
307		n = do_query(statp, dname, class, ns_t_soa, resp, &msg);
308		if (n < 0) {
309			DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
310				 dname, p_class(class), n));
311			goto cleanup;
312		}
313		if (n > 0) {
314			DPRINTF(("get_soa: CNAME or DNAME found"));
315			sect = ns_s_max, n = 0;
316		} else {
317			rcode = ns_msg_getflag(msg, ns_f_rcode);
318			ancount = ns_msg_count(msg, ns_s_an);
319			nscount = ns_msg_count(msg, ns_s_ns);
320			if (ancount > 0 && rcode == ns_r_noerror)
321				sect = ns_s_an, n = ancount;
322			else if (nscount > 0)
323				sect = ns_s_ns, n = nscount;
324			else
325				sect = ns_s_max, n = 0;
326		}
327		for (i = 0; i < n; i++) {
328			const char *t;
329			const u_char *rdata;
330			ns_rr rr;
331
332			if (ns_parserr(&msg, sect, i, &rr) < 0) {
333				DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
334					 p_section(sect, ns_o_query), i));
335				goto cleanup;
336			}
337			if (ns_rr_type(rr) == ns_t_cname ||
338			    ns_rr_type(rr) == ns_t_dname)
339				break;
340			if (ns_rr_type(rr) != ns_t_soa ||
341			    ns_rr_class(rr) != class)
342				continue;
343			t = ns_rr_name(rr);
344			switch (sect) {
345			case ns_s_an:
346				if (ns_samedomain(dname, t) == 0) {
347					DPRINTF(
348				    ("get_soa: ns_samedomain('%s', '%s') == 0",
349						dname, t)
350						);
351					errno = EPROTOTYPE;
352					goto cleanup;
353				}
354				break;
355			case ns_s_ns:
356				if (ns_samename(dname, t) == 1 ||
357				    ns_samedomain(dname, t) == 0) {
358					DPRINTF(
359		       ("get_soa: ns_samename() || !ns_samedomain('%s', '%s')",
360						dname, t)
361						);
362					errno = EPROTOTYPE;
363					goto cleanup;
364				}
365				break;
366			default:
367				abort();
368			}
369			if (strlen(t) + 1 > zsize) {
370				DPRINTF(("get_soa: zname(%lu) too small (%lu)",
371					 (unsigned long)zsize,
372					 (unsigned long)strlen(t) + 1));
373				errno = EMSGSIZE;
374				goto cleanup;
375			}
376			strcpy(zname, t);
377			rdata = ns_rr_rdata(rr);
378			if (ns_name_uncompress(resp, ns_msg_end(msg), rdata,
379					       mname, msize) < 0) {
380				DPRINTF(("get_soa: ns_name_uncompress failed")
381					);
382				goto cleanup;
383			}
384			if (save_ns(statp, &msg, ns_s_ns,
385				    zname, class, opts, nsrrsp) < 0) {
386				DPRINTF(("get_soa: save_ns failed"));
387				goto cleanup;
388			}
389			free(resp);
390			return (0);
391		}
392
393		/* If we're out of labels, then not even "." has an SOA! */
394		if (*dname == '\0')
395			break;
396
397		/* Find label-terminating "."; top of loop will skip it. */
398		while (*dname != '.') {
399			if (*dname == '\\')
400				if (*++dname == '\0') {
401					errno = EMSGSIZE;
402					goto cleanup;
403				}
404			dname++;
405		}
406	}
407	DPRINTF(("get_soa: out of labels"));
408	errno = EDESTADDRREQ;
409 cleanup:
410	if (resp != NULL)
411		free(resp);
412	return (-1);
413}
414
415static int
416get_ns(res_state statp, const char *zname, ns_class class, int opts,
417      rrset_ns *nsrrsp)
418{
419	u_char *resp;
420	ns_msg msg;
421	int n;
422
423	resp = malloc(NS_MAXMSG);
424	if (resp == NULL)
425		return (-1);
426
427	/* Go and get the NS RRs for this zone. */
428	n = do_query(statp, zname, class, ns_t_ns, resp, &msg);
429	if (n != 0) {
430		DPRINTF(("get_ns: do_query('%s', %s) failed (%d)",
431			 zname, p_class(class), n));
432		free(resp);
433		return (-1);
434	}
435
436	/* Remember the NS RRs and associated A RRs that came back. */
437	if (save_ns(statp, &msg, ns_s_an, zname, class, opts, nsrrsp) < 0) {
438		DPRINTF(("get_ns save_ns('%s', %s) failed",
439			 zname, p_class(class)));
440		free(resp);
441		return (-1);
442	}
443
444	free(resp);
445	return (0);
446}
447
448static int
449get_glue(res_state statp, ns_class class, int opts, rrset_ns *nsrrsp) {
450	rr_ns *nsrr, *nsrr_n;
451	u_char *resp;
452
453	resp = malloc(NS_MAXMSG);
454	if (resp == NULL)
455		return(-1);
456
457	/* Go and get the A RRs for each empty NS RR on our list. */
458	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
459		ns_msg msg;
460		int n;
461
462		nsrr_n = NEXT(nsrr, link);
463
464		if ((nsrr->flags & RR_NS_HAVE_V4) == 0) {
465			n = do_query(statp, nsrr->name, class, ns_t_a,
466				     resp, &msg);
467			if (n < 0) {
468				DPRINTF(
469				       ("get_glue: do_query('%s', %s') failed",
470					nsrr->name, p_class(class)));
471				goto cleanup;
472			}
473			if (n > 0) {
474				DPRINTF((
475			"get_glue: do_query('%s', %s') CNAME or DNAME found",
476					 nsrr->name, p_class(class)));
477			}
478			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
479				   opts, nsrr) < 0) {
480				DPRINTF(("get_glue: save_r('%s', %s) failed",
481					 nsrr->name, p_class(class)));
482				goto cleanup;
483			}
484		}
485
486		if ((nsrr->flags & RR_NS_HAVE_V6) == 0) {
487			n = do_query(statp, nsrr->name, class, ns_t_aaaa,
488				     resp, &msg);
489			if (n < 0) {
490				DPRINTF(
491				       ("get_glue: do_query('%s', %s') failed",
492					nsrr->name, p_class(class)));
493				goto cleanup;
494			}
495			if (n > 0) {
496				DPRINTF((
497			"get_glue: do_query('%s', %s') CNAME or DNAME found",
498					 nsrr->name, p_class(class)));
499			}
500			if (save_a(statp, &msg, ns_s_an, nsrr->name, class,
501				   opts, nsrr) < 0) {
502				DPRINTF(("get_glue: save_r('%s', %s) failed",
503					 nsrr->name, p_class(class)));
504				goto cleanup;
505			}
506		}
507
508		/* If it's still empty, it's just chaff. */
509		if (EMPTY(nsrr->addrs)) {
510			DPRINTF(("get_glue: removing empty '%s' NS",
511				 nsrr->name));
512			free_nsrr(nsrrsp, nsrr);
513		}
514	}
515	free(resp);
516	return (0);
517
518 cleanup:
519	free(resp);
520	return (-1);
521}
522
523static int
524save_ns(res_state statp, ns_msg *msg, ns_sect sect,
525	const char *owner, ns_class class, int opts,
526	rrset_ns *nsrrsp)
527{
528	int i;
529
530	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
531		char tname[MAXDNAME];
532		const u_char *rdata;
533		rr_ns *nsrr;
534		ns_rr rr;
535
536		if (ns_parserr(msg, sect, i, &rr) < 0) {
537			DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
538				 p_section(sect, ns_o_query), i));
539			return (-1);
540		}
541		if (ns_rr_type(rr) != ns_t_ns ||
542		    ns_rr_class(rr) != class ||
543		    ns_samename(ns_rr_name(rr), owner) != 1)
544			continue;
545		nsrr = find_ns(nsrrsp, ns_rr_name(rr));
546		if (nsrr == NULL) {
547			nsrr = malloc(sizeof *nsrr);
548			if (nsrr == NULL) {
549				DPRINTF(("save_ns: malloc failed"));
550				return (-1);
551			}
552			rdata = ns_rr_rdata(rr);
553			if (ns_name_uncompress(ns_msg_base(*msg),
554					       ns_msg_end(*msg), rdata,
555					       tname, sizeof tname) < 0) {
556				DPRINTF(("save_ns: ns_name_uncompress failed")
557					);
558				free(nsrr);
559				return (-1);
560			}
561			nsrr->name = strdup(tname);
562			if (nsrr->name == NULL) {
563				DPRINTF(("save_ns: strdup failed"));
564				free(nsrr);
565				return (-1);
566			}
567			INIT_LINK(nsrr, link);
568			INIT_LIST(nsrr->addrs);
569			nsrr->flags = 0;
570			APPEND(*nsrrsp, nsrr, link);
571		}
572		if (save_a(statp, msg, ns_s_ar,
573			   nsrr->name, class, opts, nsrr) < 0) {
574			DPRINTF(("save_ns: save_r('%s', %s) failed",
575				 nsrr->name, p_class(class)));
576			return (-1);
577		}
578	}
579	return (0);
580}
581
582static int
583save_a(res_state statp, ns_msg *msg, ns_sect sect,
584       const char *owner, ns_class class, int opts,
585       rr_ns *nsrr)
586{
587	int i;
588
589	for (i = 0; i < ns_msg_count(*msg, sect); i++) {
590		ns_rr rr;
591		rr_a *arr;
592
593		if (ns_parserr(msg, sect, i, &rr) < 0) {
594			DPRINTF(("save_a: ns_parserr(%s, %d) failed",
595				 p_section(sect, ns_o_query), i));
596			return (-1);
597		}
598		if ((ns_rr_type(rr) != ns_t_a &&
599		     ns_rr_type(rr) != ns_t_aaaa) ||
600		    ns_rr_class(rr) != class ||
601		    ns_samename(ns_rr_name(rr), owner) != 1 ||
602		    ns_rr_rdlen(rr) != NS_INADDRSZ)
603			continue;
604		if ((opts & RES_IPV6ONLY) != 0 && ns_rr_type(rr) != ns_t_aaaa)
605			continue;
606		if ((opts & RES_IPV4ONLY) != 0 && ns_rr_type(rr) != ns_t_a)
607			continue;
608		arr = malloc(sizeof *arr);
609		if (arr == NULL) {
610			DPRINTF(("save_a: malloc failed"));
611			return (-1);
612		}
613		INIT_LINK(arr, link);
614		memset(&arr->addr, 0, sizeof(arr->addr));
615		switch (ns_rr_type(rr)) {
616		case ns_t_a:
617			arr->addr.sin.sin_family = AF_INET;
618#ifdef HAVE_SA_LEN
619			arr->addr.sin.sin_len = sizeof(arr->addr.sin);
620#endif
621			memcpy(&arr->addr.sin.sin_addr, ns_rr_rdata(rr),
622			       NS_INADDRSZ);
623			arr->addr.sin.sin_port = htons(NAMESERVER_PORT);
624			nsrr->flags |= RR_NS_HAVE_V4;
625			break;
626		case ns_t_aaaa:
627			arr->addr.sin6.sin6_family = AF_INET6;
628#ifdef HAVE_SA_LEN
629			arr->addr.sin6.sin6_len = sizeof(arr->addr.sin6);
630#endif
631			memcpy(&arr->addr.sin6.sin6_addr, ns_rr_rdata(rr), 16);
632			arr->addr.sin6.sin6_port = htons(NAMESERVER_PORT);
633			nsrr->flags |= RR_NS_HAVE_V6;
634			break;
635		default:
636			abort();
637		}
638		APPEND(nsrr->addrs, arr, link);
639	}
640	return (0);
641}
642
643static void
644free_nsrrset(rrset_ns *nsrrsp) {
645	rr_ns *nsrr;
646
647	while ((nsrr = HEAD(*nsrrsp)) != NULL)
648		free_nsrr(nsrrsp, nsrr);
649}
650
651static void
652free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
653	rr_a *arr;
654	char *tmp;
655
656	while ((arr = HEAD(nsrr->addrs)) != NULL) {
657		UNLINK(nsrr->addrs, arr, link);
658		free(arr);
659	}
660	DE_CONST(nsrr->name, tmp);
661	free(tmp);
662	UNLINK(*nsrrsp, nsrr, link);
663	free(nsrr);
664}
665
666static rr_ns *
667find_ns(rrset_ns *nsrrsp, const char *dname) {
668	rr_ns *nsrr;
669
670	for (nsrr = HEAD(*nsrrsp); nsrr != NULL; nsrr = NEXT(nsrr, link))
671		if (ns_samename(nsrr->name, dname) == 1)
672			return (nsrr);
673	return (NULL);
674}
675
676static int
677do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
678	 u_char *resp, ns_msg *msg)
679{
680	u_char req[NS_PACKETSZ];
681	int i, n;
682
683	n = res_nmkquery(statp, ns_o_query, dname, class, qtype,
684			 NULL, 0, NULL, req, NS_PACKETSZ);
685	if (n < 0) {
686		DPRINTF(("do_query: res_nmkquery failed"));
687		return (-1);
688	}
689	n = res_nsend(statp, req, n, resp, NS_MAXMSG);
690	if (n < 0) {
691		DPRINTF(("do_query: res_nsend failed"));
692		return (-1);
693	}
694	if (n == 0) {
695		DPRINTF(("do_query: res_nsend returned 0"));
696		errno = EMSGSIZE;
697		return (-1);
698	}
699	if (ns_initparse(resp, n, msg) < 0) {
700		DPRINTF(("do_query: ns_initparse failed"));
701		return (-1);
702	}
703	n = 0;
704	for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
705		ns_rr rr;
706
707		if (ns_parserr(msg, ns_s_an, i, &rr) < 0) {
708			DPRINTF(("do_query: ns_parserr failed"));
709			return (-1);
710		}
711		n += (ns_rr_class(rr) == class &&
712		      (ns_rr_type(rr) == ns_t_cname ||
713		       ns_rr_type(rr) == ns_t_dname));
714	}
715	return (n);
716}
717
718static void
719res_dprintf(const char *fmt, ...) {
720	va_list ap;
721
722	va_start(ap, fmt);
723	fputs(";; res_findzonecut: ", stderr);
724	vfprintf(stderr, fmt, ap);
725	fputc('\n', stderr);
726	va_end(ap);
727}
728
729/*! \file */
730