1: #if !defined(lint) && !defined(SABER)
2: static const char rcsid[] = "$Id: res_findzonecut.c,v 1.1.1.1 2012/10/09 09:06:54 misho Exp $";
3: #endif /* not lint */
4:
5: /*
6: * Copyright (c) 2009-2010 by Internet Systems Consortium, Inc. ("ISC")
7: * Copyright (c) 2004 by Internet Systems Consortium, Inc. ("ISC")
8: * Copyright (c) 1999-2003 by Internet Software Consortium
9: *
10: * Permission to use, copy, modify, and distribute this software for any
11: * purpose with or without fee is hereby granted, provided that the above
12: * copyright notice and this permission notice appear in all copies.
13: *
14: * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
15: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
16: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR
17: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
18: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
19: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
20: * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
21: *
22: * Internet Systems Consortium, Inc.
23: * 950 Charter Street
24: * Redwood City, CA 94063
25: * <info@isc.org>
26: * https://www.isc.org/
27: */
28:
29: /* Import. */
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:
38: #include <errno.h>
39: #include <limits.h>
40: #include <netdb.h>
41: #include <stdarg.h>
42: #include <stdio.h>
43: #include <stdlib.h>
44: #include <string.h>
45:
46: #include <isc-dhcp/list.h>
47:
48: #include "minires/minires.h"
49: #include "arpa/nameser.h"
50:
51: /* Data structures. */
52:
53: typedef struct rr_a {
54: ISC_LINK(struct rr_a) link;
55: struct in_addr addr;
56: } rr_a;
57: typedef ISC_LIST(rr_a) rrset_a;
58:
59: typedef struct rr_ns {
60: ISC_LINK(struct rr_ns) link;
61: char *name;
62: rrset_a addrs;
63: } rr_ns;
64: typedef ISC_LIST(rr_ns) rrset_ns;
65:
66: /* Forward. */
67:
68: static int satisfy(res_state,
69: const char *, rrset_ns *, struct in_addr *, int);
70: static int add_addrs(res_state, rr_ns *, struct in_addr *, int);
71: static isc_result_t get_soa(res_state, const char *, ns_class,
72: char *, size_t, char *, size_t,
73: rrset_ns *);
74: static isc_result_t get_ns(res_state, const char *, ns_class, rrset_ns *);
75: static isc_result_t get_glue(res_state, ns_class, rrset_ns *);
76: static isc_result_t save_ns(res_state, ns_msg *, ns_sect,
77: const char *, ns_class, rrset_ns *);
78: static isc_result_t save_a(res_state, ns_msg *, ns_sect,
79: const char *, ns_class, rrset_a *);
80: static void free_nsrrset(rrset_ns *);
81: static void free_nsrr(rrset_ns *, rr_ns *);
82: static rr_ns * find_ns(rrset_ns *, const char *);
83: static isc_result_t do_query(res_state, const char *, ns_class, ns_type,
84: double *, ns_msg *, int *);
85:
86: /* Public. */
87:
88: /*
89: * int
90: * res_findzonecut(res, dname, class, zname, zsize, addrs, naddrs)
91: * find enclosing zone for a <dname,class>, and some server addresses
92: * parameters:
93: * res - resolver context to work within (is modified)
94: * dname - domain name whose enclosing zone is desired
95: * class - class of dname (and its enclosing zone)
96: * zname - found zone name
97: * zsize - allocated size of zname
98: * addrs - found server addresses
99: * naddrs - max number of addrs
100: * return values:
101: * < 0 - an error occurred (check errno)
102: * = 0 - zname is now valid, but addrs[] wasn't changed
103: * > 0 - zname is now valid, and return value is number of addrs[] found
104: * notes:
105: * this function calls res_nsend() which means it depends on correctly
106: * functioning recursive nameservers (usually defined in /etc/resolv.conf
107: * or its local equivilent).
108: *
109: * we start by asking for an SOA<dname,class>. if we get one as an
110: * answer, that just means <dname,class> is a zone top, which is fine.
111: * more than likely we'll be told to go pound sand, in the form of a
112: * negative answer.
113: *
114: * note that we are not prepared to deal with referrals since that would
115: * only come from authority servers and our correctly functioning local
116: * recursive server would have followed the referral and got us something
117: * more definite.
118: *
119: * if the authority section contains an SOA, this SOA should also be the
120: * closest enclosing zone, since any intermediary zone cuts would've been
121: * returned as referrals and dealt with by our correctly functioning local
122: * recursive name server. but an SOA in the authority section should NOT
123: * match our dname (since that would have been returned in the answer
124: * section). an authority section SOA has to be "above" our dname.
125: *
126: * we cannot fail to find an SOA in this way. ultimately we'll return
127: * a zname indicating the root zone if that's the closest enclosing zone.
128: * however, since authority section SOA's were once optional, it's
129: * possible that we'll have to go hunting for the enclosing SOA by
130: * ripping labels off the front of our dname -- this is known as "doing
131: * it the hard way."
132: *
133: * ultimately we want some server addresses, which are ideally the ones
134: * pertaining to the SOA.MNAME, but only if there is a matching NS RR.
135: * so the second phase (after we find an SOA) is to go looking for the
136: * NS RRset for that SOA's zone.
137: *
138: * no answer section processed by this code is allowed to contain CNAME
139: * or DNAME RR's. for the SOA query this means we strip a label and
140: * keep going. for the NS and A queries this means we just give up.
141: */
142:
143: isc_result_t
144: res_findzonecut(res_state statp, const char *dname, ns_class class, int opts,
145: char *zname, size_t zsize, struct in_addr *addrs, int naddrs,
146: int *count, void *zcookie)
147: {
148: char mname[NS_MAXDNAME];
149: u_long save_pfcode;
150: rrset_ns nsrrs;
151: int n = 0;
152: isc_result_t rcode;
153:
154: DPRINTF(("START dname='%s' class=%s, zsize=%ld, naddrs=%d",
155: dname, p_class(class), (long)zsize, naddrs));
156: save_pfcode = statp->pfcode;
157: statp->pfcode |= RES_PRF_HEAD2 | RES_PRF_HEAD1 | RES_PRF_HEADX |
158: RES_PRF_QUES | RES_PRF_ANS |
159: RES_PRF_AUTH | RES_PRF_ADD;
160: ISC_LIST_INIT(nsrrs);
161:
162: DPRINTF (("look for a predefined zone statement"));
163: rcode = find_cached_zone (dname, class, zname, zsize,
164: addrs, naddrs, &n, zcookie);
165: if (rcode == ISC_R_SUCCESS)
166: goto done;
167:
168: DPRINTF(("get the soa, and see if it has enough glue"));
169: if ((rcode = get_soa(statp, dname, class, zname, zsize,
170: mname, sizeof mname, &nsrrs)) != ISC_R_SUCCESS ||
171: ((opts & RES_EXHAUSTIVE) == 0 &&
172: (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
173: goto done;
174:
175: DPRINTF(("get the ns rrset and see if it has enough glue"));
176: if ((rcode = get_ns(statp, zname, class, &nsrrs)) != ISC_R_SUCCESS ||
177: ((opts & RES_EXHAUSTIVE) == 0 &&
178: (n = satisfy(statp, mname, &nsrrs, addrs, naddrs)) > 0))
179: goto done;
180:
181: DPRINTF(("get the missing glue and see if it's finally enough"));
182: if ((rcode = get_glue(statp, class, &nsrrs)) == ISC_R_SUCCESS)
183: n = satisfy(statp, mname, &nsrrs, addrs, naddrs);
184:
185: /* If we found the zone, cache it. */
186: if (n > 0)
187: cache_found_zone (class, zname, addrs, n);
188: done:
189: DPRINTF(("FINISH n=%d (%s)", n, (n < 0) ? strerror(errno) : "OK"));
190: free_nsrrset(&nsrrs);
191: statp->pfcode = save_pfcode;
192: if (count)
193: *count = n;
194: return rcode;
195: }
196:
197: /* Private. */
198:
199: static int
200: satisfy(res_state statp,
201: const char *mname, rrset_ns *nsrrsp, struct in_addr *addrs, int naddrs)
202: {
203: rr_ns *nsrr;
204: int n, x;
205:
206: n = 0;
207: nsrr = find_ns(nsrrsp, mname);
208: if (nsrr != NULL) {
209: x = add_addrs(statp, nsrr, addrs, naddrs);
210: addrs += x;
211: naddrs -= x;
212: n += x;
213: }
214: for (nsrr = ISC_LIST_HEAD(*nsrrsp);
215: nsrr != NULL && naddrs > 0;
216: nsrr = ISC_LIST_NEXT(nsrr, link))
217: if (ns_samename(nsrr->name, mname) != 1) {
218: x = add_addrs(statp, nsrr, addrs, naddrs);
219: addrs += x;
220: naddrs -= x;
221: n += x;
222: }
223: DPRINTF(("satisfy(%s): %d", mname, n));
224: return (n);
225: }
226:
227: static int
228: add_addrs(res_state statp, rr_ns *nsrr, struct in_addr *addrs, int naddrs) {
229: rr_a *arr;
230: int n = 0;
231:
232: for (arr = ISC_LIST_HEAD(nsrr->addrs);
233: arr != NULL; arr = ISC_LIST_NEXT(arr, link)) {
234: if (naddrs <= 0)
235: return (0);
236: *addrs++ = arr->addr;
237: naddrs--;
238: n++;
239: }
240: DPRINTF(("add_addrs: %d", n));
241: return (n);
242: }
243:
244: static isc_result_t
245: get_soa(res_state statp, const char *dname, ns_class class,
246: char *zname, size_t zsize, char *mname, size_t msize,
247: rrset_ns *nsrrsp)
248: {
249: char tname[NS_MAXDNAME];
250: double resp[NS_PACKETSZ / sizeof (double)];
251: int n, i, ancount, nscount;
252: ns_sect sect;
253: ns_msg msg;
254: isc_result_t rcode;
255:
256: /*
257: * Find closest enclosing SOA, even if it's for the root zone.
258: */
259:
260: /* First canonicalize dname (exactly one unescaped trailing "."). */
261: rcode = ns_makecanon(dname, tname, sizeof tname);
262: if (rcode != ISC_R_SUCCESS)
263: return rcode;
264: dname = tname;
265:
266: /* Now grovel the subdomains, hunting for an SOA answer or auth. */
267: for (;;) {
268: /* Leading or inter-label '.' are skipped here. */
269: while (*dname == '.')
270: dname++;
271:
272: /* Is there an SOA? */
273: rcode = do_query(statp, dname, class, ns_t_soa,
274: resp, &msg, &n);
275: if (rcode != ISC_R_SUCCESS) {
276: DPRINTF(("get_soa: do_query('%s', %s) failed (%d)",
277: dname, p_class(class), n));
278: return rcode;
279: }
280: if (n > 0) {
281: DPRINTF(("get_soa: CNAME or DNAME found"));
282: sect = ns_s_max, n = 0;
283: } else {
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;
290: else
291: sect = ns_s_max, n = 0;
292: }
293: for (i = 0; i < n; i++) {
294: const char *t;
295: const u_char *rdata;
296: ns_rr rr;
297:
298: rcode = ns_parserr(&msg, sect, i, &rr) < 0;
299: if (rcode != ISC_R_SUCCESS) {
300: DPRINTF(("get_soa: ns_parserr(%s, %d) failed",
301: p_section(sect, ns_o_query), i));
302: return rcode;
303: }
304: if (ns_rr_type(rr) == ns_t_cname ||
305: ns_rr_type(rr) == ns_t_dname)
306: break;
307: if (ns_rr_type(rr) != ns_t_soa ||
308: ns_rr_class(rr) != class)
309: continue;
310: t = ns_rr_name(rr);
311: switch (sect) {
312: case ns_s_an:
313: if (ns_samedomain(dname, t) == 0) {
314: DPRINTF(("get_soa: %s'%s', '%s') == 0",
315: "ns_samedomain(", dname, t));
316: return ISC_R_NOTZONE;
317: }
318: break;
319: case ns_s_ns:
320: if (ns_samename(dname, t) == 1 ||
321: ns_samedomain(dname, t) == 0) {
322: DPRINTF(("get_soa: %smain('%s', '%s')",
323: "ns_samename() || !ns_samedo",
324: dname, t));
325: return ISC_R_NOTZONE;
326: }
327: break;
328: default:
329: abort();
330: }
331: if (strlen(t) + 1 > zsize) {
332: DPRINTF(("get_soa: zname(%d) too small (%d)",
333: zsize, strlen(t) + 1));
334: return ISC_R_NOSPACE;
335: }
336: strcpy(zname, t);
337: rdata = ns_rr_rdata(rr);
338: /* ns_rr_rdlen(rr); */
339: if (ns_name_uncompress((u_char *)resp,
340: ns_msg_end(msg), rdata,
341: mname, msize) < 0) {
342: DPRINTF(("get_soa: %s failed",
343: "ns_name_uncompress"));
344: return ISC_R_NOMEMORY;
345: }
346: rcode = save_ns(statp, &msg,
347: ns_s_ns, zname, class, nsrrsp);
348: if (rcode != ISC_R_SUCCESS) {
349: DPRINTF(("get_soa: save_ns failed"));
350: return rcode;
351: }
352: return ISC_R_SUCCESS;
353: }
354:
355: /* If we're out of labels, then not even "." has an SOA! */
356: if (*dname == '\0')
357: break;
358:
359: /* Find label-terminating "."; top of loop will skip it. */
360: while (*dname != '.') {
361: if (*dname == '\\')
362: if (*++dname == '\0') {
363: return ISC_R_NOSPACE;
364: }
365: dname++;
366: }
367: }
368: DPRINTF(("get_soa: out of labels"));
369: return ISC_R_DESTADDRREQ;
370: }
371:
372: static isc_result_t
373: get_ns(res_state statp, const char *zname, ns_class class, rrset_ns *nsrrsp) {
374: double resp[NS_PACKETSZ / sizeof (double)];
375: ns_msg msg;
376: int n;
377: isc_result_t rcode;
378:
379: /* Go and get the NS RRs for this zone. */
380: rcode = do_query(statp, zname, class, ns_t_ns, resp, &msg, &n);
381: if (rcode != ISC_R_SUCCESS) {
382: DPRINTF(("get_ns: do_query('zname', %s) failed (%d)",
383: zname, p_class(class), rcode));
384: return rcode;
385: }
386:
387: /* Remember the NS RRs and associated A RRs that came back. */
388: rcode = save_ns(statp, &msg, ns_s_an, zname, class, nsrrsp);
389: if (rcode != ISC_R_SUCCESS) {
390: DPRINTF(("get_ns save_ns('%s', %s) failed",
391: zname, p_class(class)));
392: return rcode;
393: }
394:
395: return ISC_R_SUCCESS;
396: }
397:
398: static isc_result_t
399: get_glue(res_state statp, ns_class class, rrset_ns *nsrrsp) {
400: rr_ns *nsrr, *nsrr_n;
401:
402: /* Go and get the A RRs for each empty NS RR on our list. */
403: for (nsrr = ISC_LIST_HEAD(*nsrrsp); nsrr != NULL; nsrr = nsrr_n) {
404: double resp[NS_PACKETSZ / sizeof (double)];
405: ns_msg msg;
406: int n;
407: isc_result_t rcode;
408:
409: nsrr_n = ISC_LIST_NEXT(nsrr, link);
410:
411: if (ISC_LIST_EMPTY(nsrr->addrs)) {
412: rcode = do_query(statp, nsrr->name, class, ns_t_a,
413: resp, &msg, &n);
414: if (rcode != ISC_R_SUCCESS) {
415: DPRINTF(("get_glue: do_query('%s', %s') failed",
416: nsrr->name, p_class(class)));
417: return rcode;
418: }
419: if (n > 0) {
420: DPRINTF((
421: "get_glue: do_query('%s', %s') CNAME or DNAME found",
422: nsrr->name, p_class(class)));
423: }
424: rcode = save_a(statp, &msg, ns_s_an, nsrr->name, class,
425: &nsrr->addrs);
426: if (rcode != ISC_R_SUCCESS) {
427: DPRINTF(("get_glue: save_r('%s', %s) failed",
428: nsrr->name, p_class(class)));
429: return rcode;
430: }
431: /* If it's still empty, it's just chaff. */
432: if (ISC_LIST_EMPTY(nsrr->addrs)) {
433: DPRINTF(("get_glue: removing empty '%s' NS",
434: nsrr->name));
435: free_nsrr(nsrrsp, nsrr);
436: }
437: }
438: }
439: return ISC_R_SUCCESS;
440: }
441:
442: static isc_result_t
443: save_ns(res_state statp, ns_msg *msg, ns_sect sect,
444: const char *owner, ns_class class,
445: rrset_ns *nsrrsp)
446: {
447: int i;
448: isc_result_t rcode;
449:
450: for (i = 0; i < ns_msg_count(*msg, sect); i++) {
451: char tname[MAXDNAME];
452: const u_char *rdata;
453: rr_ns *nsrr;
454: ns_rr rr;
455:
456: rcode = ns_parserr(msg, sect, i, &rr);
457: if (rcode != ISC_R_SUCCESS) {
458: DPRINTF(("save_ns: ns_parserr(%s, %d) failed",
459: p_section(sect, ns_o_query), i));
460: return rcode;
461: }
462: if (ns_rr_type(rr) != ns_t_ns ||
463: ns_rr_class(rr) != class ||
464: ns_samename(ns_rr_name(rr), owner) != 1)
465: continue;
466: nsrr = find_ns(nsrrsp, ns_rr_name(rr));
467: if (nsrr == NULL) {
468: nsrr = malloc(sizeof *nsrr);
469: if (nsrr == NULL) {
470: DPRINTF(("save_ns: malloc failed"));
471: return ISC_R_NOMEMORY;
472: }
473: rdata = ns_rr_rdata(rr);
474: /* ns_rr_rdlen(rr); */
475: if (ns_name_uncompress(ns_msg_base(*msg),
476: ns_msg_end(*msg), rdata,
477: tname, sizeof tname) < 0) {
478: DPRINTF(("save_ns: ns_name_uncompress failed"));
479: free(nsrr);
480: return ISC_R_NOMEMORY;
481: }
482: nsrr->name = strdup(tname);
483: if (nsrr->name == NULL) {
484: DPRINTF(("save_ns: strdup failed"));
485: free(nsrr);
486: return ISC_R_NOMEMORY;
487: }
488: ISC_LIST_INIT(nsrr->addrs);
489: ISC_LIST_APPEND(*nsrrsp, nsrr, link);
490: }
491: rcode = save_a(statp, msg, ns_s_ar,
492: nsrr->name, class, &nsrr->addrs);
493: if (rcode != ISC_R_SUCCESS) {
494: DPRINTF(("save_ns: save_r('%s', %s) failed",
495: nsrr->name, p_class(class)));
496: return rcode;
497: }
498: }
499: return ISC_R_SUCCESS;
500: }
501:
502: static isc_result_t
503: save_a(res_state statp, ns_msg *msg, ns_sect sect,
504: const char *owner, ns_class class,
505: rrset_a *arrsp)
506: {
507: int i;
508: isc_result_t rcode;
509:
510: for (i = 0; i < ns_msg_count(*msg, sect); i++) {
511: ns_rr rr;
512: rr_a *arr;
513:
514: rcode = ns_parserr(msg, sect, i, &rr);
515: if (rcode != ISC_R_SUCCESS) {
516: DPRINTF(("save_a: ns_parserr(%s, %d) failed",
517: p_section(sect, ns_o_query), i));
518: return rcode;
519: }
520: if (ns_rr_type(rr) != ns_t_a ||
521: ns_rr_class(rr) != class ||
522: ns_samename(ns_rr_name(rr), owner) != 1 ||
523: ns_rr_rdlen(rr) != NS_INADDRSZ)
524: continue;
525: arr = malloc(sizeof *arr);
526: if (arr == NULL) {
527: DPRINTF(("save_a: malloc failed"));
528: return ISC_R_NOMEMORY;
529: }
530: memcpy(&arr->addr, ns_rr_rdata(rr), NS_INADDRSZ);
531: ISC_LIST_APPEND(*arrsp, arr, link);
532: }
533: return ISC_R_SUCCESS;
534: }
535:
536: static void
537: free_nsrrset(rrset_ns *nsrrsp) {
538: rr_ns *nsrr;
539:
540: while ((nsrr = ISC_LIST_HEAD(*nsrrsp)) != NULL)
541: free_nsrr(nsrrsp, nsrr);
542: }
543:
544: static void
545: free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
546: rr_a *arr;
547:
548: while ((arr = ISC_LIST_HEAD(nsrr->addrs)) != NULL) {
549: ISC_LIST_UNLINK(nsrr->addrs, arr, link);
550: free(arr);
551: }
552: free((char *)nsrr->name);
553: ISC_LIST_UNLINK(*nsrrsp, nsrr, link);
554: free(nsrr);
555: }
556:
557: static rr_ns *
558: find_ns(rrset_ns *nsrrsp, const char *dname) {
559: rr_ns *nsrr;
560:
561: for (nsrr = ISC_LIST_HEAD(*nsrrsp);
562: nsrr != NULL; nsrr = ISC_LIST_NEXT(nsrr, link))
563: if (ns_samename(nsrr->name, dname) == 1)
564: return (nsrr);
565: return (NULL);
566: }
567:
568: static isc_result_t
569: do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
570: double *resp, ns_msg *msg, int *alias_count)
571: {
572: double req[NS_PACKETSZ / sizeof (double)];
573: int i;
574: unsigned n;
575: isc_result_t status;
576:
577: status = res_nmkquery(statp, ns_o_query, dname, class, qtype,
578: NULL, 0, NULL, req, NS_PACKETSZ, &n);
579: if (status != ISC_R_SUCCESS) {
580: DPRINTF(("do_query: res_nmkquery failed"));
581: return status;
582: }
583: status = res_nsend(statp, req, n, resp, NS_PACKETSZ, &n);
584: if (status != ISC_R_SUCCESS) {
585: DPRINTF(("do_query: res_nsend failed"));
586: return status;
587: }
588: if (n == 0) {
589: DPRINTF(("do_query: res_nsend returned 0"));
590: return ISC_R_NOTFOUND;
591: }
592: if (ns_initparse((u_char *)resp, n, msg) < 0) {
593: DPRINTF(("do_query: ns_initparse failed"));
594: return ISC_R_NOSPACE;
595: }
596: n = 0;
597: for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
598: ns_rr rr;
599:
600: status = ns_parserr(msg, ns_s_an, i, &rr);
601: if (status != ISC_R_SUCCESS) {
602: DPRINTF(("do_query: ns_parserr failed"));
603: return status;
604: }
605: n += (ns_rr_class(rr) == class &&
606: (ns_rr_type(rr) == ns_t_cname ||
607: ns_rr_type(rr) == ns_t_dname));
608: }
609: if (alias_count)
610: *alias_count = n;
611: return ISC_R_SUCCESS;
612: }
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