1 #if !defined(lint) && !defined(SABER)
2 static const char rcsid[] = "$Id: res_findzonecut.c,v 1.14.2.4 2004/06/10 17:59:43 dhankins Exp $";
6 * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
7 * Copyright (c) 1999-2003 by Internet Software Consortium
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.
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.
21 * Internet Systems Consortium, Inc.
23 * Redwood City, CA 94063
30 #include <sys/param.h>
31 #include <sys/socket.h>
34 #include <netinet/in.h>
35 #include <arpa/inet.h>
45 #include <isc-dhcp/list.h>
47 #include "minires/minires.h"
48 #include "arpa/nameser.h"
50 /* Data structures. */
53 ISC_LINK(struct rr_a) link;
56 typedef ISC_LIST(rr_a) rrset_a;
58 typedef struct rr_ns {
59 ISC_LINK(struct rr_ns) link;
63 typedef ISC_LIST(rr_ns) rrset_ns;
67 static int satisfy(res_state,
68 const char *, rrset_ns *, struct in_addr *, int);
69 static int add_addrs(res_state, rr_ns *, struct in_addr *, int);
70 static ns_rcode get_soa(res_state, const char *, ns_class,
71 char *, size_t, char *, size_t,
73 static isc_result_t get_ns(res_state, const char *, ns_class, rrset_ns *);
74 static isc_result_t get_glue(res_state, ns_class, rrset_ns *);
75 static isc_result_t save_ns(res_state, ns_msg *, ns_sect,
76 const char *, ns_class, rrset_ns *);
77 static isc_result_t save_a(res_state, ns_msg *, ns_sect,
78 const char *, ns_class, rrset_a *);
79 static void free_nsrrset(rrset_ns *);
80 static void free_nsrr(rrset_ns *, rr_ns *);
81 static rr_ns * find_ns(rrset_ns *, const char *);
82 static isc_result_t do_query(res_state, const char *, ns_class, ns_type,
83 double *, ns_msg *, int *);
89 * res_findzonecut(res, dname, class, zname, zsize, addrs, naddrs)
90 * find enclosing zone for a <dname,class>, and some server addresses
92 * res - resolver context to work within (is modified)
93 * dname - domain name whose enclosing zone is desired
94 * class - class of dname (and its enclosing zone)
95 * zname - found zone name
96 * zsize - allocated size of zname
97 * addrs - found server addresses
98 * naddrs - max number of addrs
100 * < 0 - an error occurred (check errno)
101 * = 0 - zname is now valid, but addrs[] wasn't changed
102 * > 0 - zname is now valid, and return value is number of addrs[] found
104 * this function calls res_nsend() which means it depends on correctly
105 * functioning recursive nameservers (usually defined in /etc/resolv.conf
106 * or its local equivilent).
108 * we start by asking for an SOA<dname,class>. if we get one as an
109 * answer, that just means <dname,class> is a zone top, which is fine.
110 * more than likely we'll be told to go pound sand, in the form of a
113 * note that we are not prepared to deal with referrals since that would
114 * only come from authority servers and our correctly functioning local
115 * recursive server would have followed the referral and got us something
118 * if the authority section contains an SOA, this SOA should also be the
119 * closest enclosing zone, since any intermediary zone cuts would've been
120 * returned as referrals and dealt with by our correctly functioning local
121 * recursive name server. but an SOA in the authority section should NOT
122 * match our dname (since that would have been returned in the answer
123 * section). an authority section SOA has to be "above" our dname.
125 * we cannot fail to find an SOA in this way. ultimately we'll return
126 * a zname indicating the root zone if that's the closest enclosing zone.
127 * however, since authority section SOA's were once optional, it's
128 * possible that we'll have to go hunting for the enclosing SOA by
129 * ripping labels off the front of our dname -- this is known as "doing
132 * ultimately we want some server addresses, which are ideally the ones
133 * pertaining to the SOA.MNAME, but only if there is a matching NS RR.
134 * so the second phase (after we find an SOA) is to go looking for the
135 * NS RRset for that SOA's zone.
137 * no answer section processed by this code is allowed to contain CNAME
138 * or DNAME RR's. for the SOA query this means we strip a label and
139 * keep going. for the NS and A queries this means we just give up.
143 res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
144 char *zname, size_t zsize, struct in_addr *addrs, int naddrs,
145 int *count, void *zcookie)
147 char mname[NS_MAXDNAME];
153 DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
154 dname, p_class(class), (long)zsize, naddrs));
155 save_pfcode = statp->pfcode;
156 statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
157 RES_PRF_QUES | RES_PRF_ANS |
158 RES_PRF_AUTH | RES_PRF_ADD;
159 ISC_LIST_INIT(nsrrs);
161 DPRINTF (("look for a predefined zone statement"));
162 rcode = find_cached_zone (dname, class, zname, zsize,
163 addrs, naddrs, &n, zcookie);
164 if (rcode == ISC_R_SUCCESS)
167 DPRINTF(("get the soa, and see if it has enough glue"));
168 if ((rcode = get_soa(statp, dname, class, zname, zsize,
169 mname, sizeof mname, &nsrrs)) != ISC_R_SUCCESS ||
170 ((opts & RES_EXHAUSTIVE) == 0 &&
171 (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
174 DPRINTF(("get the ns rrset and see if it has enough glue"));
175 if ((rcode = get_ns(statp, zname, class, &nsrrs)) != ISC_R_SUCCESS ||
176 ((opts & RES_EXHAUSTIVE) == 0 &&
177 (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
180 DPRINTF(("get the missing glue and see if it's finally enough"));
181 if ((rcode = get_glue(statp, class, &nsrrs)) == ISC_R_SUCCESS)
182 n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
184 /* If we found the zone, cache it. */
186 cache_found_zone (class, zname, addrs, n);
188 DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
189 free_nsrrset(&nsrrs);
190 statp->pfcode = save_pfcode;
199 satisfy(res_state statp,
200 const char *mname, rrset_ns *nsrrsp, struct in_addr *addrs, int naddrs)
206 nsrr = find_ns(nsrrsp, mname);
208 x = add_addrs(statp, nsrr, addrs, naddrs);
213 for (nsrr = ISC_LIST_HEAD(*nsrrsp);
214 nsrr != NULL && naddrs > 0;
215 nsrr = ISC_LIST_NEXT(nsrr, link))
216 if (ns_samename(nsrr->name, mname) != 1) {
217 x = add_addrs(statp, nsrr, addrs, naddrs);
222 DPRINTF(("satisfy(%s): %d", mname, n));
227 add_addrs(res_state statp, rr_ns *nsrr, struct in_addr *addrs, int naddrs) {
231 for (arr = ISC_LIST_HEAD(nsrr->addrs);
232 arr != NULL; arr = ISC_LIST_NEXT(arr, link)) {
235 *addrs++ = arr->addr;
239 DPRINTF(("add_addrs: %d", n));
244 get_soa(res_state statp, const char *dname, ns_class class,
245 char *zname, size_t zsize, char *mname, size_t msize,
248 char tname[NS_MAXDNAME];
249 double resp[NS_PACKETSZ / sizeof (double)];
250 int n, i, ancount, nscount;
257 * Find closest enclosing SOA, even if it's for the root zone.
260 /* First canonicalize dname (exactly one unescaped trailing "."). */
261 status = ns_makecanon(dname, tname, sizeof tname);
262 if (status != ISC_R_SUCCESS)
266 /* Now grovel the subdomains, hunting for an SOA answer or auth. */
268 /* Leading or inter-label '.' are skipped here. */
269 while (*dname == '.')
272 /* Is there an SOA? */
273 rcode = do_query(statp, dname, class, ns_t_soa,
275 if (rcode != ISC_R_SUCCESS) {
276 DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
277 dname, p_class(class), n));
281 DPRINTF(("get_soa: CNAME or DNAME found"));
282 sect = ns_s_max, n = 0;
284 ancount = ns_msg_count(msg, ns_s_an);
285 nscount = ns_msg_count(msg, ns_s_ns);
286 if (ancount > 0 && rcode == ISC_R_SUCCESS)
287 sect = ns_s_an, n = ancount;
288 else if (nscount > 0)
289 sect = ns_s_ns, n = nscount;
291 sect = ns_s_max, n = 0;
293 for (i = 0; i < n; i++) {
299 rcode = ns_parserr(&msg, sect, i, &rr) < 0;
300 if (rcode != ISC_R_SUCCESS) {
301 DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
302 p_section(sect, ns_o_query), i));
305 if (ns_rr_type(rr) == ns_t_cname ||
306 ns_rr_type(rr) == ns_t_dname)
308 if (ns_rr_type(rr) != ns_t_soa ||
309 ns_rr_class(rr) != class)
314 if (ns_samedomain(dname, t) == 0) {
315 DPRINTF(("get_soa: %s'%s', '%s') == 0",
316 "ns_samedomain(", dname, t));
317 return ISC_R_NOTZONE;
321 if (ns_samename(dname, t) == 1 ||
322 ns_samedomain(dname, t) == 0) {
323 DPRINTF(("get_soa: %smain('%s', '%s')",
324 "ns_samename() || !ns_samedo",
326 return ISC_R_NOTZONE;
332 if (strlen(t) + 1 > zsize) {
333 DPRINTF(("get_soa: zname(%d) too small (%d)",
334 zsize, strlen(t) + 1));
335 return ISC_R_NOSPACE;
338 rdata = ns_rr_rdata(rr);
339 rdlen = ns_rr_rdlen(rr);
340 if (ns_name_uncompress((u_char *)resp,
341 ns_msg_end(msg), rdata,
343 DPRINTF(("get_soa: %s failed",
344 "ns_name_uncompress"));
345 return ISC_R_NOMEMORY;
347 rcode = save_ns(statp, &msg,
348 ns_s_ns, zname, class, nsrrsp);
349 if (rcode != ISC_R_SUCCESS) {
350 DPRINTF(("get_soa: save_ns failed"));
353 return ISC_R_SUCCESS;
356 /* If we're out of labels, then not even "." has an SOA! */
360 /* Find label-terminating "."; top of loop will skip it. */
361 while (*dname != '.') {
363 if (*++dname == '\0') {
364 return ISC_R_NOSPACE;
369 DPRINTF(("get_soa: out of labels"));
370 return ISC_R_DESTADDRREQ;
374 get_ns(res_state statp, const char *zname, ns_class class, rrset_ns *nsrrsp) {
375 double resp[NS_PACKETSZ / sizeof (double)];
380 /* Go and get the NS RRs for this zone. */
381 rcode = do_query(statp, zname, class, ns_t_ns, resp, &msg, &n);
382 if (rcode != ISC_R_SUCCESS) {
383 DPRINTF(("get_ns: do_query('zname', %s) failed (%d)",
384 zname, p_class(class), rcode));
388 /* Remember the NS RRs and associated A RRs that came back. */
389 rcode = save_ns(statp, &msg, ns_s_an, zname, class, nsrrsp);
390 if (rcode != ISC_R_SUCCESS) {
391 DPRINTF(("get_ns save_ns('%s', %s) failed",
392 zname, p_class(class)));
396 return ISC_R_SUCCESS;
400 get_glue(res_state statp, ns_class class, rrset_ns *nsrrsp) {
401 rr_ns *nsrr, *nsrr_n;
403 /* Go and get the A RRs for each empty NS RR on our list. */
404 for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
405 double resp[NS_PACKETSZ / sizeof (double)];
410 nsrr_n = ISC_LIST_NEXT(nsrr, link);
412 if (ISC_LIST_EMPTY(nsrr->addrs)) {
413 rcode = do_query(statp, nsrr->name, class, ns_t_a,
415 if (rcode != ISC_R_SUCCESS) {
416 DPRINTF(("get_glue: do_query('%s', %s') failed",
417 nsrr->name, p_class(class)));
422 "get_glue: do_query('%s', %s') CNAME or DNAME found",
423 nsrr->name, p_class(class)));
425 rcode = save_a(statp, &msg, ns_s_an, nsrr->name, class,
427 if (rcode != ISC_R_SUCCESS) {
428 DPRINTF(("get_glue: save_r('%s', %s) failed",
429 nsrr->name, p_class(class)));
432 /* If it's still empty, it's just chaff. */
433 if (ISC_LIST_EMPTY(nsrr->addrs)) {
434 DPRINTF(("get_glue: removing empty '%s' NS",
436 free_nsrr(nsrrsp, nsrr);
440 return ISC_R_SUCCESS;
444 save_ns(res_state statp, ns_msg *msg, ns_sect sect,
445 const char *owner, ns_class class,
451 for (i = 0; i < ns_msg_count(*msg, sect); i++) {
452 char tname[MAXDNAME];
458 rcode = ns_parserr(msg, sect, i, &rr);
459 if (rcode != ISC_R_SUCCESS) {
460 DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
461 p_section(sect, ns_o_query), i));
464 if (ns_rr_type(rr) != ns_t_ns ||
465 ns_rr_class(rr) != class ||
466 ns_samename(ns_rr_name(rr), owner) != 1)
468 nsrr = find_ns(nsrrsp, ns_rr_name(rr));
470 nsrr = malloc(sizeof *nsrr);
472 DPRINTF(("save_ns: malloc failed"));
473 return ISC_R_NOMEMORY;
475 rdata = ns_rr_rdata(rr);
476 rdlen = ns_rr_rdlen(rr);
477 if (ns_name_uncompress(ns_msg_base(*msg),
478 ns_msg_end(*msg), rdata,
479 tname, sizeof tname) < 0) {
480 DPRINTF(("save_ns: ns_name_uncompress failed"));
482 return ISC_R_NOMEMORY;
484 nsrr->name = strdup(tname);
485 if (nsrr->name == NULL) {
486 DPRINTF(("save_ns: strdup failed"));
488 return ISC_R_NOMEMORY;
490 ISC_LIST_INIT(nsrr->addrs);
491 ISC_LIST_APPEND(*nsrrsp, nsrr, link);
493 rcode = save_a(statp, msg, ns_s_ar,
494 nsrr->name, class, &nsrr->addrs);
495 if (rcode != ISC_R_SUCCESS) {
496 DPRINTF(("save_ns: save_r('%s', %s) failed",
497 nsrr->name, p_class(class)));
501 return ISC_R_SUCCESS;
505 save_a(res_state statp, ns_msg *msg, ns_sect sect,
506 const char *owner, ns_class class,
512 for (i = 0; i < ns_msg_count(*msg, sect); i++) {
516 rcode = ns_parserr(msg, sect, i, &rr);
517 if (rcode != ISC_R_SUCCESS) {
518 DPRINTF(("save_a: ns_parserr(%s, %d) failed",
519 p_section(sect, ns_o_query), i));
522 if (ns_rr_type(rr) != ns_t_a ||
523 ns_rr_class(rr) != class ||
524 ns_samename(ns_rr_name(rr), owner) != 1 ||
525 ns_rr_rdlen(rr) != NS_INADDRSZ)
527 arr = malloc(sizeof *arr);
529 DPRINTF(("save_a: malloc failed"));
530 return ISC_R_NOMEMORY;
532 memcpy(&arr->addr, ns_rr_rdata(rr), NS_INADDRSZ);
533 ISC_LIST_APPEND(*arrsp, arr, link);
535 return ISC_R_SUCCESS;
539 free_nsrrset(rrset_ns *nsrrsp) {
542 while ((nsrr = ISC_LIST_HEAD(*nsrrsp)) != NULL)
543 free_nsrr(nsrrsp, nsrr);
547 free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
550 while ((arr = ISC_LIST_HEAD(nsrr->addrs)) != NULL) {
551 ISC_LIST_UNLINK(nsrr->addrs, arr, link);
554 free((char *)nsrr->name);
555 ISC_LIST_UNLINK(*nsrrsp, nsrr, link);
560 find_ns(rrset_ns *nsrrsp, const char *dname) {
563 for (nsrr = ISC_LIST_HEAD(*nsrrsp);
564 nsrr != NULL; nsrr = ISC_LIST_NEXT(nsrr, link))
565 if (ns_samename(nsrr->name, dname) == 1)
571 do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
572 double *resp, ns_msg *msg, int *alias_count)
574 double req[NS_PACKETSZ / sizeof (double)];
579 status = res_nmkquery(statp, ns_o_query, dname, class, qtype,
580 NULL, 0, NULL, req, NS_PACKETSZ, &n);
581 if (status != ISC_R_SUCCESS) {
582 DPRINTF(("do_query: res_nmkquery failed"));
585 status = res_nsend(statp, req, n, resp, NS_PACKETSZ, &n);
586 if (status != ISC_R_SUCCESS) {
587 DPRINTF(("do_query: res_nsend failed"));
591 DPRINTF(("do_query: res_nsend returned 0"));
592 return ISC_R_NOTFOUND;
594 if (ns_initparse((u_char *)resp, n, msg) < 0) {
595 DPRINTF(("do_query: ns_initparse failed"));
596 return ISC_R_NOSPACE;
599 for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
602 status = ns_parserr(msg, ns_s_an, i, &rr);
603 if (status != ISC_R_SUCCESS) {
604 DPRINTF(("do_query: ns_parserr failed"));
607 n += (ns_rr_class(rr) == class &&
608 (ns_rr_type(rr) == ns_t_cname ||
609 ns_rr_type(rr) == ns_t_dname));
613 return ISC_R_SUCCESS;