1: #if !defined(lint) && !defined(SABER)
2: static const char rcsid[] = "$Id: res_findzonecut.c,v 1.1 2012/02/21 22:30:18 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: int rdlen;
297: ns_rr rr;
298:
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));
303: return rcode;
304: }
305: if (ns_rr_type(rr) == ns_t_cname ||
306: ns_rr_type(rr) == ns_t_dname)
307: break;
308: if (ns_rr_type(rr) != ns_t_soa ||
309: ns_rr_class(rr) != class)
310: continue;
311: t = ns_rr_name(rr);
312: switch (sect) {
313: case ns_s_an:
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;
318: }
319: break;
320: case ns_s_ns:
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",
325: dname, t));
326: return ISC_R_NOTZONE;
327: }
328: break;
329: default:
330: abort();
331: }
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;
336: }
337: strcpy(zname, t);
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,
342: mname, msize) < 0) {
343: DPRINTF(("get_soa: %s failed",
344: "ns_name_uncompress"));
345: return ISC_R_NOMEMORY;
346: }
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"));
351: return rcode;
352: }
353: return ISC_R_SUCCESS;
354: }
355:
356: /* If we're out of labels, then not even "." has an SOA! */
357: if (*dname == '\0')
358: break;
359:
360: /* Find label-terminating "."; top of loop will skip it. */
361: while (*dname != '.') {
362: if (*dname == '\\')
363: if (*++dname == '\0') {
364: return ISC_R_NOSPACE;
365: }
366: dname++;
367: }
368: }
369: DPRINTF(("get_soa: out of labels"));
370: return ISC_R_DESTADDRREQ;
371: }
372:
373: static isc_result_t
374: get_ns(res_state statp, const char *zname, ns_class class, rrset_ns *nsrrsp) {
375: double resp[NS_PACKETSZ / sizeof (double)];
376: ns_msg msg;
377: int n;
378: isc_result_t rcode;
379:
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));
385: return rcode;
386: }
387:
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)));
393: return rcode;
394: }
395:
396: return ISC_R_SUCCESS;
397: }
398:
399: static isc_result_t
400: get_glue(res_state statp, ns_class class, rrset_ns *nsrrsp) {
401: rr_ns *nsrr, *nsrr_n;
402:
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)];
406: ns_msg msg;
407: int n;
408: isc_result_t rcode;
409:
410: nsrr_n = ISC_LIST_NEXT(nsrr, link);
411:
412: if (ISC_LIST_EMPTY(nsrr->addrs)) {
413: rcode = do_query(statp, nsrr->name, class, ns_t_a,
414: resp, &msg, &n);
415: if (rcode != ISC_R_SUCCESS) {
416: DPRINTF(("get_glue: do_query('%s', %s') failed",
417: nsrr->name, p_class(class)));
418: return rcode;
419: }
420: if (n > 0) {
421: DPRINTF((
422: "get_glue: do_query('%s', %s') CNAME or DNAME found",
423: nsrr->name, p_class(class)));
424: }
425: rcode = save_a(statp, &msg, ns_s_an, nsrr->name, class,
426: &nsrr->addrs);
427: if (rcode != ISC_R_SUCCESS) {
428: DPRINTF(("get_glue: save_r('%s', %s) failed",
429: nsrr->name, p_class(class)));
430: return rcode;
431: }
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",
435: nsrr->name));
436: free_nsrr(nsrrsp, nsrr);
437: }
438: }
439: }
440: return ISC_R_SUCCESS;
441: }
442:
443: static isc_result_t
444: save_ns(res_state statp, ns_msg *msg, ns_sect sect,
445: const char *owner, ns_class class,
446: rrset_ns *nsrrsp)
447: {
448: int i;
449: isc_result_t rcode;
450:
451: for (i = 0; i < ns_msg_count(*msg, sect); i++) {
452: char tname[MAXDNAME];
453: const u_char *rdata;
454: rr_ns *nsrr;
455: ns_rr rr;
456: int rdlen;
457:
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));
462: return rcode;
463: }
464: if (ns_rr_type(rr) != ns_t_ns ||
465: ns_rr_class(rr) != class ||
466: ns_samename(ns_rr_name(rr), owner) != 1)
467: continue;
468: nsrr = find_ns(nsrrsp, ns_rr_name(rr));
469: if (nsrr == NULL) {
470: nsrr = malloc(sizeof *nsrr);
471: if (nsrr == NULL) {
472: DPRINTF(("save_ns: malloc failed"));
473: return ISC_R_NOMEMORY;
474: }
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"));
481: free(nsrr);
482: return ISC_R_NOMEMORY;
483: }
484: nsrr->name = strdup(tname);
485: if (nsrr->name == NULL) {
486: DPRINTF(("save_ns: strdup failed"));
487: free(nsrr);
488: return ISC_R_NOMEMORY;
489: }
490: ISC_LIST_INIT(nsrr->addrs);
491: ISC_LIST_APPEND(*nsrrsp, nsrr, link);
492: }
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)));
498: return rcode;
499: }
500: }
501: return ISC_R_SUCCESS;
502: }
503:
504: static isc_result_t
505: save_a(res_state statp, ns_msg *msg, ns_sect sect,
506: const char *owner, ns_class class,
507: rrset_a *arrsp)
508: {
509: int i;
510: isc_result_t rcode;
511:
512: for (i = 0; i < ns_msg_count(*msg, sect); i++) {
513: ns_rr rr;
514: rr_a *arr;
515:
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));
520: return rcode;
521: }
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)
526: continue;
527: arr = malloc(sizeof *arr);
528: if (arr == NULL) {
529: DPRINTF(("save_a: malloc failed"));
530: return ISC_R_NOMEMORY;
531: }
532: memcpy(&arr->addr, ns_rr_rdata(rr), NS_INADDRSZ);
533: ISC_LIST_APPEND(*arrsp, arr, link);
534: }
535: return ISC_R_SUCCESS;
536: }
537:
538: static void
539: free_nsrrset(rrset_ns *nsrrsp) {
540: rr_ns *nsrr;
541:
542: while ((nsrr = ISC_LIST_HEAD(*nsrrsp)) != NULL)
543: free_nsrr(nsrrsp, nsrr);
544: }
545:
546: static void
547: free_nsrr(rrset_ns *nsrrsp, rr_ns *nsrr) {
548: rr_a *arr;
549:
550: while ((arr = ISC_LIST_HEAD(nsrr->addrs)) != NULL) {
551: ISC_LIST_UNLINK(nsrr->addrs, arr, link);
552: free(arr);
553: }
554: free((char *)nsrr->name);
555: ISC_LIST_UNLINK(*nsrrsp, nsrr, link);
556: free(nsrr);
557: }
558:
559: static rr_ns *
560: find_ns(rrset_ns *nsrrsp, const char *dname) {
561: rr_ns *nsrr;
562:
563: for (nsrr = ISC_LIST_HEAD(*nsrrsp);
564: nsrr != NULL; nsrr = ISC_LIST_NEXT(nsrr, link))
565: if (ns_samename(nsrr->name, dname) == 1)
566: return (nsrr);
567: return (NULL);
568: }
569:
570: static isc_result_t
571: do_query(res_state statp, const char *dname, ns_class class, ns_type qtype,
572: double *resp, ns_msg *msg, int *alias_count)
573: {
574: double req[NS_PACKETSZ / sizeof (double)];
575: int i;
576: unsigned n;
577: isc_result_t status;
578:
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"));
583: return status;
584: }
585: status = res_nsend(statp, req, n, resp, NS_PACKETSZ, &n);
586: if (status != ISC_R_SUCCESS) {
587: DPRINTF(("do_query: res_nsend failed"));
588: return status;
589: }
590: if (n == 0) {
591: DPRINTF(("do_query: res_nsend returned 0"));
592: return ISC_R_NOTFOUND;
593: }
594: if (ns_initparse((u_char *)resp, n, msg) < 0) {
595: DPRINTF(("do_query: ns_initparse failed"));
596: return ISC_R_NOSPACE;
597: }
598: n = 0;
599: for (i = 0; i < ns_msg_count(*msg, ns_s_an); i++) {
600: ns_rr rr;
601:
602: status = ns_parserr(msg, ns_s_an, i, &rr);
603: if (status != ISC_R_SUCCESS) {
604: DPRINTF(("do_query: ns_parserr failed"));
605: return status;
606: }
607: n += (ns_rr_class(rr) == class &&
608: (ns_rr_type(rr) == ns_t_cname ||
609: ns_rr_type(rr) == ns_t_dname));
610: }
611: if (alias_count)
612: *alias_count = n;
613: return ISC_R_SUCCESS;
614: }
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