1 /*
2 * services/cache/dns.c - Cache services for DNS using msg and rrset caches.
3 *
4 * Copyright (c) 2007, NLnet Labs. All rights reserved.
5 *
6 * This software is open source.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 *
12 * Redistributions of source code must retain the above copyright notice,
13 * this list of conditions and the following disclaimer.
14 *
15 * Redistributions in binary form must reproduce the above copyright notice,
16 * this list of conditions and the following disclaimer in the documentation
17 * and/or other materials provided with the distribution.
18 *
19 * Neither the name of the NLNET LABS nor the names of its contributors may
20 * be used to endorse or promote products derived from this software without
21 * specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
24 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
25 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
26 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
27 * HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
28 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED
29 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
30 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
31 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
32 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35
36 /**
37 * \file
38 *
39 * This file contains the DNS cache.
40 */
41 #include "config.h"
42 #include "iterator/iter_delegpt.h"
43 #include "validator/val_nsec.h"
44 #include "services/cache/dns.h"
45 #include "services/cache/rrset.h"
46 #include "util/data/msgreply.h"
47 #include "util/data/packed_rrset.h"
48 #include "util/data/dname.h"
49 #include "util/module.h"
50 #include "util/net_help.h"
51 #include "util/regional.h"
52 #include "util/config_file.h"
53 #include "sldns/sbuffer.h"
54
55 /** store rrsets in the rrset cache.
56 * @param env: module environment with caches.
57 * @param rep: contains list of rrsets to store.
58 * @param now: current time.
59 * @param leeway: during prefetch how much leeway to update TTLs.
60 * This makes rrsets (other than type NS) timeout sooner so they get
61 * updated with a new full TTL.
62 * Type NS does not get this, because it must not be refreshed from the
63 * child domain, but keep counting down properly.
64 * @param pside: if from parentside discovered NS, so that its NS is okay
65 * in a prefetch situation to be updated (without becoming sticky).
66 * @param qrep: update rrsets here if cache is better
67 * @param region: for qrep allocs.
68 */
69 static void
store_rrsets(struct module_env * env,struct reply_info * rep,time_t now,time_t leeway,int pside,struct reply_info * qrep,struct regional * region)70 store_rrsets(struct module_env* env, struct reply_info* rep, time_t now,
71 time_t leeway, int pside, struct reply_info* qrep,
72 struct regional* region)
73 {
74 size_t i;
75 /* see if rrset already exists in cache, if not insert it. */
76 for(i=0; i<rep->rrset_count; i++) {
77 rep->ref[i].key = rep->rrsets[i];
78 rep->ref[i].id = rep->rrsets[i]->id;
79 /* update ref if it was in the cache */
80 switch(rrset_cache_update(env->rrset_cache, &rep->ref[i],
81 env->alloc, now + ((ntohs(rep->ref[i].key->rk.type)==
82 LDNS_RR_TYPE_NS && !pside)?0:leeway))) {
83 case 0: /* ref unchanged, item inserted */
84 break;
85 case 2: /* ref updated, cache is superior */
86 if(region) {
87 struct ub_packed_rrset_key* ck;
88 lock_rw_rdlock(&rep->ref[i].key->entry.lock);
89 /* if deleted rrset, do not copy it */
90 if(rep->ref[i].key->id == 0)
91 ck = NULL;
92 else ck = packed_rrset_copy_region(
93 rep->ref[i].key, region, now);
94 lock_rw_unlock(&rep->ref[i].key->entry.lock);
95 if(ck) {
96 /* use cached copy if memory allows */
97 qrep->rrsets[i] = ck;
98 }
99 }
100 /* no break: also copy key item */
101 case 1: /* ref updated, item inserted */
102 rep->rrsets[i] = rep->ref[i].key;
103 }
104 }
105 }
106
107 void
dns_cache_store_msg(struct module_env * env,struct query_info * qinfo,hashvalue_t hash,struct reply_info * rep,time_t leeway,int pside,struct reply_info * qrep,struct regional * region)108 dns_cache_store_msg(struct module_env* env, struct query_info* qinfo,
109 hashvalue_t hash, struct reply_info* rep, time_t leeway, int pside,
110 struct reply_info* qrep, struct regional* region)
111 {
112 struct msgreply_entry* e;
113 time_t ttl = rep->ttl;
114 size_t i;
115
116 /* store RRsets */
117 for(i=0; i<rep->rrset_count; i++) {
118 rep->ref[i].key = rep->rrsets[i];
119 rep->ref[i].id = rep->rrsets[i]->id;
120 }
121
122 /* there was a reply_info_sortref(rep) here but it seems to be
123 * unnecessary, because the cache gets locked per rrset. */
124 reply_info_set_ttls(rep, *env->now);
125 store_rrsets(env, rep, *env->now, leeway, pside, qrep, region);
126 if(ttl == 0) {
127 /* we do not store the message, but we did store the RRs,
128 * which could be useful for delegation information */
129 verbose(VERB_ALGO, "TTL 0: dropped msg from cache");
130 free(rep);
131 return;
132 }
133
134 /* store msg in the cache */
135 reply_info_sortref(rep);
136 if(!(e = query_info_entrysetup(qinfo, rep, hash))) {
137 log_err("store_msg: malloc failed");
138 return;
139 }
140 slabhash_insert(env->msg_cache, hash, &e->entry, rep, env->alloc);
141 }
142
143 /** find closest NS or DNAME and returns the rrset (locked) */
144 static struct ub_packed_rrset_key*
find_closest_of_type(struct module_env * env,uint8_t * qname,size_t qnamelen,uint16_t qclass,time_t now,uint16_t searchtype,int stripfront)145 find_closest_of_type(struct module_env* env, uint8_t* qname, size_t qnamelen,
146 uint16_t qclass, time_t now, uint16_t searchtype, int stripfront)
147 {
148 struct ub_packed_rrset_key *rrset;
149 uint8_t lablen;
150
151 if(stripfront) {
152 /* strip off so that DNAMEs have strict subdomain match */
153 lablen = *qname;
154 qname += lablen + 1;
155 qnamelen -= lablen + 1;
156 }
157
158 /* snip off front part of qname until the type is found */
159 while(qnamelen > 0) {
160 if((rrset = rrset_cache_lookup(env->rrset_cache, qname,
161 qnamelen, searchtype, qclass, 0, now, 0)))
162 return rrset;
163
164 /* snip off front label */
165 lablen = *qname;
166 qname += lablen + 1;
167 qnamelen -= lablen + 1;
168 }
169 return NULL;
170 }
171
172 /** add addr to additional section */
173 static void
addr_to_additional(struct ub_packed_rrset_key * rrset,struct regional * region,struct dns_msg * msg,time_t now)174 addr_to_additional(struct ub_packed_rrset_key* rrset, struct regional* region,
175 struct dns_msg* msg, time_t now)
176 {
177 if((msg->rep->rrsets[msg->rep->rrset_count] =
178 packed_rrset_copy_region(rrset, region, now))) {
179 msg->rep->ar_numrrsets++;
180 msg->rep->rrset_count++;
181 }
182 }
183
184 /** lookup message in message cache */
185 static struct msgreply_entry*
msg_cache_lookup(struct module_env * env,uint8_t * qname,size_t qnamelen,uint16_t qtype,uint16_t qclass,uint16_t flags,time_t now,int wr)186 msg_cache_lookup(struct module_env* env, uint8_t* qname, size_t qnamelen,
187 uint16_t qtype, uint16_t qclass, uint16_t flags, time_t now, int wr)
188 {
189 struct lruhash_entry* e;
190 struct query_info k;
191 hashvalue_t h;
192
193 k.qname = qname;
194 k.qname_len = qnamelen;
195 k.qtype = qtype;
196 k.qclass = qclass;
197 h = query_info_hash(&k, flags);
198 e = slabhash_lookup(env->msg_cache, h, &k, wr);
199
200 if(!e) return NULL;
201 if( now > ((struct reply_info*)e->data)->ttl ) {
202 lock_rw_unlock(&e->lock);
203 return NULL;
204 }
205 return (struct msgreply_entry*)e->key;
206 }
207
208 /** find and add A and AAAA records for nameservers in delegpt */
209 static int
find_add_addrs(struct module_env * env,uint16_t qclass,struct regional * region,struct delegpt * dp,time_t now,struct dns_msg ** msg)210 find_add_addrs(struct module_env* env, uint16_t qclass,
211 struct regional* region, struct delegpt* dp, time_t now,
212 struct dns_msg** msg)
213 {
214 struct delegpt_ns* ns;
215 struct msgreply_entry* neg;
216 struct ub_packed_rrset_key* akey;
217 for(ns = dp->nslist; ns; ns = ns->next) {
218 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
219 ns->namelen, LDNS_RR_TYPE_A, qclass, 0, now, 0);
220 if(akey) {
221 if(!delegpt_add_rrset_A(dp, region, akey, 0)) {
222 lock_rw_unlock(&akey->entry.lock);
223 return 0;
224 }
225 if(msg)
226 addr_to_additional(akey, region, *msg, now);
227 lock_rw_unlock(&akey->entry.lock);
228 } else {
229 /* BIT_CD on false because delegpt lookup does
230 * not use dns64 translation */
231 neg = msg_cache_lookup(env, ns->name, ns->namelen,
232 LDNS_RR_TYPE_A, qclass, 0, now, 0);
233 if(neg) {
234 delegpt_add_neg_msg(dp, neg);
235 lock_rw_unlock(&neg->entry.lock);
236 }
237 }
238 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
239 ns->namelen, LDNS_RR_TYPE_AAAA, qclass, 0, now, 0);
240 if(akey) {
241 if(!delegpt_add_rrset_AAAA(dp, region, akey, 0)) {
242 lock_rw_unlock(&akey->entry.lock);
243 return 0;
244 }
245 if(msg)
246 addr_to_additional(akey, region, *msg, now);
247 lock_rw_unlock(&akey->entry.lock);
248 } else {
249 /* BIT_CD on false because delegpt lookup does
250 * not use dns64 translation */
251 neg = msg_cache_lookup(env, ns->name, ns->namelen,
252 LDNS_RR_TYPE_AAAA, qclass, 0, now, 0);
253 if(neg) {
254 delegpt_add_neg_msg(dp, neg);
255 lock_rw_unlock(&neg->entry.lock);
256 }
257 }
258 }
259 return 1;
260 }
261
262 /** find and add A and AAAA records for missing nameservers in delegpt */
263 int
cache_fill_missing(struct module_env * env,uint16_t qclass,struct regional * region,struct delegpt * dp)264 cache_fill_missing(struct module_env* env, uint16_t qclass,
265 struct regional* region, struct delegpt* dp)
266 {
267 struct delegpt_ns* ns;
268 struct msgreply_entry* neg;
269 struct ub_packed_rrset_key* akey;
270 time_t now = *env->now;
271 for(ns = dp->nslist; ns; ns = ns->next) {
272 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
273 ns->namelen, LDNS_RR_TYPE_A, qclass, 0, now, 0);
274 if(akey) {
275 if(!delegpt_add_rrset_A(dp, region, akey, ns->lame)) {
276 lock_rw_unlock(&akey->entry.lock);
277 return 0;
278 }
279 log_nametypeclass(VERB_ALGO, "found in cache",
280 ns->name, LDNS_RR_TYPE_A, qclass);
281 lock_rw_unlock(&akey->entry.lock);
282 } else {
283 /* BIT_CD on false because delegpt lookup does
284 * not use dns64 translation */
285 neg = msg_cache_lookup(env, ns->name, ns->namelen,
286 LDNS_RR_TYPE_A, qclass, 0, now, 0);
287 if(neg) {
288 delegpt_add_neg_msg(dp, neg);
289 lock_rw_unlock(&neg->entry.lock);
290 }
291 }
292 akey = rrset_cache_lookup(env->rrset_cache, ns->name,
293 ns->namelen, LDNS_RR_TYPE_AAAA, qclass, 0, now, 0);
294 if(akey) {
295 if(!delegpt_add_rrset_AAAA(dp, region, akey, ns->lame)) {
296 lock_rw_unlock(&akey->entry.lock);
297 return 0;
298 }
299 log_nametypeclass(VERB_ALGO, "found in cache",
300 ns->name, LDNS_RR_TYPE_AAAA, qclass);
301 lock_rw_unlock(&akey->entry.lock);
302 } else {
303 /* BIT_CD on false because delegpt lookup does
304 * not use dns64 translation */
305 neg = msg_cache_lookup(env, ns->name, ns->namelen,
306 LDNS_RR_TYPE_AAAA, qclass, 0, now, 0);
307 if(neg) {
308 delegpt_add_neg_msg(dp, neg);
309 lock_rw_unlock(&neg->entry.lock);
310 }
311 }
312 }
313 return 1;
314 }
315
316 /** find and add DS or NSEC to delegation msg */
317 static void
find_add_ds(struct module_env * env,struct regional * region,struct dns_msg * msg,struct delegpt * dp,time_t now)318 find_add_ds(struct module_env* env, struct regional* region,
319 struct dns_msg* msg, struct delegpt* dp, time_t now)
320 {
321 /* Lookup the DS or NSEC at the delegation point. */
322 struct ub_packed_rrset_key* rrset = rrset_cache_lookup(
323 env->rrset_cache, dp->name, dp->namelen, LDNS_RR_TYPE_DS,
324 msg->qinfo.qclass, 0, now, 0);
325 if(!rrset) {
326 /* NOTE: this won't work for alternate NSEC schemes
327 * (opt-in, NSEC3) */
328 rrset = rrset_cache_lookup(env->rrset_cache, dp->name,
329 dp->namelen, LDNS_RR_TYPE_NSEC, msg->qinfo.qclass,
330 0, now, 0);
331 /* Note: the PACKED_RRSET_NSEC_AT_APEX flag is not used.
332 * since this is a referral, we need the NSEC at the parent
333 * side of the zone cut, not the NSEC at apex side. */
334 if(rrset && nsec_has_type(rrset, LDNS_RR_TYPE_DS)) {
335 lock_rw_unlock(&rrset->entry.lock);
336 rrset = NULL; /* discard wrong NSEC */
337 }
338 }
339 if(rrset) {
340 /* add it to auth section. This is the second rrset. */
341 if((msg->rep->rrsets[msg->rep->rrset_count] =
342 packed_rrset_copy_region(rrset, region, now))) {
343 msg->rep->ns_numrrsets++;
344 msg->rep->rrset_count++;
345 }
346 lock_rw_unlock(&rrset->entry.lock);
347 }
348 }
349
350 struct dns_msg*
dns_msg_create(uint8_t * qname,size_t qnamelen,uint16_t qtype,uint16_t qclass,struct regional * region,size_t capacity)351 dns_msg_create(uint8_t* qname, size_t qnamelen, uint16_t qtype,
352 uint16_t qclass, struct regional* region, size_t capacity)
353 {
354 struct dns_msg* msg = (struct dns_msg*)regional_alloc(region,
355 sizeof(struct dns_msg));
356 if(!msg)
357 return NULL;
358 msg->qinfo.qname = regional_alloc_init(region, qname, qnamelen);
359 if(!msg->qinfo.qname)
360 return NULL;
361 msg->qinfo.qname_len = qnamelen;
362 msg->qinfo.qtype = qtype;
363 msg->qinfo.qclass = qclass;
364 /* non-packed reply_info, because it needs to grow the array */
365 msg->rep = (struct reply_info*)regional_alloc_zero(region,
366 sizeof(struct reply_info)-sizeof(struct rrset_ref));
367 if(!msg->rep)
368 return NULL;
369 if(capacity > RR_COUNT_MAX)
370 return NULL; /* integer overflow protection */
371 msg->rep->flags = BIT_QR; /* with QR, no AA */
372 msg->rep->qdcount = 1;
373 msg->rep->rrsets = (struct ub_packed_rrset_key**)
374 regional_alloc(region,
375 capacity*sizeof(struct ub_packed_rrset_key*));
376 if(!msg->rep->rrsets)
377 return NULL;
378 return msg;
379 }
380
381 int
dns_msg_authadd(struct dns_msg * msg,struct regional * region,struct ub_packed_rrset_key * rrset,time_t now)382 dns_msg_authadd(struct dns_msg* msg, struct regional* region,
383 struct ub_packed_rrset_key* rrset, time_t now)
384 {
385 if(!(msg->rep->rrsets[msg->rep->rrset_count++] =
386 packed_rrset_copy_region(rrset, region, now)))
387 return 0;
388 msg->rep->ns_numrrsets++;
389 return 1;
390 }
391
392 /** add rrset to answer section */
393 static int
dns_msg_ansadd(struct dns_msg * msg,struct regional * region,struct ub_packed_rrset_key * rrset,time_t now)394 dns_msg_ansadd(struct dns_msg* msg, struct regional* region,
395 struct ub_packed_rrset_key* rrset, time_t now)
396 {
397 if(!(msg->rep->rrsets[msg->rep->rrset_count++] =
398 packed_rrset_copy_region(rrset, region, now)))
399 return 0;
400 msg->rep->an_numrrsets++;
401 return 1;
402 }
403
404 struct delegpt*
dns_cache_find_delegation(struct module_env * env,uint8_t * qname,size_t qnamelen,uint16_t qtype,uint16_t qclass,struct regional * region,struct dns_msg ** msg,time_t now)405 dns_cache_find_delegation(struct module_env* env, uint8_t* qname,
406 size_t qnamelen, uint16_t qtype, uint16_t qclass,
407 struct regional* region, struct dns_msg** msg, time_t now)
408 {
409 /* try to find closest NS rrset */
410 struct ub_packed_rrset_key* nskey;
411 struct packed_rrset_data* nsdata;
412 struct delegpt* dp;
413
414 nskey = find_closest_of_type(env, qname, qnamelen, qclass, now,
415 LDNS_RR_TYPE_NS, 0);
416 if(!nskey) /* hope the caller has hints to prime or something */
417 return NULL;
418 nsdata = (struct packed_rrset_data*)nskey->entry.data;
419 /* got the NS key, create delegation point */
420 dp = delegpt_create(region);
421 if(!dp || !delegpt_set_name(dp, region, nskey->rk.dname)) {
422 lock_rw_unlock(&nskey->entry.lock);
423 log_err("find_delegation: out of memory");
424 return NULL;
425 }
426 /* create referral message */
427 if(msg) {
428 /* allocate the array to as much as we could need:
429 * NS rrset + DS/NSEC rrset +
430 * A rrset for every NS RR
431 * AAAA rrset for every NS RR
432 */
433 *msg = dns_msg_create(qname, qnamelen, qtype, qclass, region,
434 2 + nsdata->count*2);
435 if(!*msg || !dns_msg_authadd(*msg, region, nskey, now)) {
436 lock_rw_unlock(&nskey->entry.lock);
437 log_err("find_delegation: out of memory");
438 return NULL;
439 }
440 }
441 if(!delegpt_rrset_add_ns(dp, region, nskey, 0))
442 log_err("find_delegation: addns out of memory");
443 lock_rw_unlock(&nskey->entry.lock); /* first unlock before next lookup*/
444 /* find and add DS/NSEC (if any) */
445 if(msg)
446 find_add_ds(env, region, *msg, dp, now);
447 /* find and add A entries */
448 if(!find_add_addrs(env, qclass, region, dp, now, msg))
449 log_err("find_delegation: addrs out of memory");
450 return dp;
451 }
452
453 /** allocate dns_msg from query_info and reply_info */
454 static struct dns_msg*
gen_dns_msg(struct regional * region,struct query_info * q,size_t num)455 gen_dns_msg(struct regional* region, struct query_info* q, size_t num)
456 {
457 struct dns_msg* msg = (struct dns_msg*)regional_alloc(region,
458 sizeof(struct dns_msg));
459 if(!msg)
460 return NULL;
461 memcpy(&msg->qinfo, q, sizeof(struct query_info));
462 msg->qinfo.qname = regional_alloc_init(region, q->qname, q->qname_len);
463 if(!msg->qinfo.qname)
464 return NULL;
465 /* allocate replyinfo struct and rrset key array separately */
466 msg->rep = (struct reply_info*)regional_alloc(region,
467 sizeof(struct reply_info) - sizeof(struct rrset_ref));
468 if(!msg->rep)
469 return NULL;
470 if(num > RR_COUNT_MAX)
471 return NULL; /* integer overflow protection */
472 msg->rep->rrsets = (struct ub_packed_rrset_key**)
473 regional_alloc(region,
474 num * sizeof(struct ub_packed_rrset_key*));
475 if(!msg->rep->rrsets)
476 return NULL;
477 return msg;
478 }
479
480 /** generate dns_msg from cached message */
481 static struct dns_msg*
tomsg(struct module_env * env,struct query_info * q,struct reply_info * r,struct regional * region,time_t now,struct regional * scratch)482 tomsg(struct module_env* env, struct query_info* q, struct reply_info* r,
483 struct regional* region, time_t now, struct regional* scratch)
484 {
485 struct dns_msg* msg;
486 size_t i;
487 if(now > r->ttl)
488 return NULL;
489 msg = gen_dns_msg(region, q, r->rrset_count);
490 if(!msg)
491 return NULL;
492 msg->rep->flags = r->flags;
493 msg->rep->qdcount = r->qdcount;
494 msg->rep->ttl = r->ttl - now;
495 if(r->prefetch_ttl > now)
496 msg->rep->prefetch_ttl = r->prefetch_ttl - now;
497 else msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(msg->rep->ttl);
498 msg->rep->security = r->security;
499 msg->rep->an_numrrsets = r->an_numrrsets;
500 msg->rep->ns_numrrsets = r->ns_numrrsets;
501 msg->rep->ar_numrrsets = r->ar_numrrsets;
502 msg->rep->rrset_count = r->rrset_count;
503 msg->rep->authoritative = r->authoritative;
504 if(!rrset_array_lock(r->ref, r->rrset_count, now))
505 return NULL;
506 if(r->an_numrrsets > 0 && (r->rrsets[0]->rk.type == htons(
507 LDNS_RR_TYPE_CNAME) || r->rrsets[0]->rk.type == htons(
508 LDNS_RR_TYPE_DNAME)) && !reply_check_cname_chain(q, r)) {
509 /* cname chain is now invalid, reconstruct msg */
510 rrset_array_unlock(r->ref, r->rrset_count);
511 return NULL;
512 }
513 if(r->security == sec_status_secure && !reply_all_rrsets_secure(r)) {
514 /* message rrsets have changed status, revalidate */
515 rrset_array_unlock(r->ref, r->rrset_count);
516 return NULL;
517 }
518 for(i=0; i<msg->rep->rrset_count; i++) {
519 msg->rep->rrsets[i] = packed_rrset_copy_region(r->rrsets[i],
520 region, now);
521 if(!msg->rep->rrsets[i]) {
522 rrset_array_unlock(r->ref, r->rrset_count);
523 return NULL;
524 }
525 }
526 rrset_array_unlock_touch(env->rrset_cache, scratch, r->ref,
527 r->rrset_count);
528 return msg;
529 }
530
531 /** synthesize RRset-only response from cached RRset item */
532 static struct dns_msg*
rrset_msg(struct ub_packed_rrset_key * rrset,struct regional * region,time_t now,struct query_info * q)533 rrset_msg(struct ub_packed_rrset_key* rrset, struct regional* region,
534 time_t now, struct query_info* q)
535 {
536 struct dns_msg* msg;
537 struct packed_rrset_data* d = (struct packed_rrset_data*)
538 rrset->entry.data;
539 if(now > d->ttl)
540 return NULL;
541 msg = gen_dns_msg(region, q, 1); /* only the CNAME (or other) RRset */
542 if(!msg)
543 return NULL;
544 msg->rep->flags = BIT_QR; /* reply, no AA, no error */
545 msg->rep->authoritative = 0; /* reply stored in cache can't be authoritative */
546 msg->rep->qdcount = 1;
547 msg->rep->ttl = d->ttl - now;
548 msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(msg->rep->ttl);
549 msg->rep->security = sec_status_unchecked;
550 msg->rep->an_numrrsets = 1;
551 msg->rep->ns_numrrsets = 0;
552 msg->rep->ar_numrrsets = 0;
553 msg->rep->rrset_count = 1;
554 msg->rep->rrsets[0] = packed_rrset_copy_region(rrset, region, now);
555 if(!msg->rep->rrsets[0]) /* copy CNAME */
556 return NULL;
557 return msg;
558 }
559
560 /** synthesize DNAME+CNAME response from cached DNAME item */
561 static struct dns_msg*
synth_dname_msg(struct ub_packed_rrset_key * rrset,struct regional * region,time_t now,struct query_info * q)562 synth_dname_msg(struct ub_packed_rrset_key* rrset, struct regional* region,
563 time_t now, struct query_info* q)
564 {
565 struct dns_msg* msg;
566 struct ub_packed_rrset_key* ck;
567 struct packed_rrset_data* newd, *d = (struct packed_rrset_data*)
568 rrset->entry.data;
569 uint8_t* newname, *dtarg = NULL;
570 size_t newlen, dtarglen;
571 if(now > d->ttl)
572 return NULL;
573 /* only allow validated (with DNSSEC) DNAMEs used from cache
574 * for insecure DNAMEs, query again. */
575 if(d->security != sec_status_secure)
576 return NULL;
577 msg = gen_dns_msg(region, q, 2); /* DNAME + CNAME RRset */
578 if(!msg)
579 return NULL;
580 msg->rep->flags = BIT_QR; /* reply, no AA, no error */
581 msg->rep->authoritative = 0; /* reply stored in cache can't be authoritative */
582 msg->rep->qdcount = 1;
583 msg->rep->ttl = d->ttl - now;
584 msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(msg->rep->ttl);
585 msg->rep->security = sec_status_unchecked;
586 msg->rep->an_numrrsets = 1;
587 msg->rep->ns_numrrsets = 0;
588 msg->rep->ar_numrrsets = 0;
589 msg->rep->rrset_count = 1;
590 msg->rep->rrsets[0] = packed_rrset_copy_region(rrset, region, now);
591 if(!msg->rep->rrsets[0]) /* copy DNAME */
592 return NULL;
593 /* synth CNAME rrset */
594 get_cname_target(rrset, &dtarg, &dtarglen);
595 if(!dtarg)
596 return NULL;
597 newlen = q->qname_len + dtarglen - rrset->rk.dname_len;
598 if(newlen > LDNS_MAX_DOMAINLEN) {
599 msg->rep->flags |= LDNS_RCODE_YXDOMAIN;
600 return msg;
601 }
602 newname = (uint8_t*)regional_alloc(region, newlen);
603 if(!newname)
604 return NULL;
605 /* new name is concatenation of qname front (without DNAME owner)
606 * and DNAME target name */
607 memcpy(newname, q->qname, q->qname_len-rrset->rk.dname_len);
608 memmove(newname+(q->qname_len-rrset->rk.dname_len), dtarg, dtarglen);
609 /* create rest of CNAME rrset */
610 ck = (struct ub_packed_rrset_key*)regional_alloc(region,
611 sizeof(struct ub_packed_rrset_key));
612 if(!ck)
613 return NULL;
614 memset(&ck->entry, 0, sizeof(ck->entry));
615 msg->rep->rrsets[1] = ck;
616 ck->entry.key = ck;
617 ck->rk.type = htons(LDNS_RR_TYPE_CNAME);
618 ck->rk.rrset_class = rrset->rk.rrset_class;
619 ck->rk.flags = 0;
620 ck->rk.dname = regional_alloc_init(region, q->qname, q->qname_len);
621 if(!ck->rk.dname)
622 return NULL;
623 ck->rk.dname_len = q->qname_len;
624 ck->entry.hash = rrset_key_hash(&ck->rk);
625 newd = (struct packed_rrset_data*)regional_alloc_zero(region,
626 sizeof(struct packed_rrset_data) + sizeof(size_t) +
627 sizeof(uint8_t*) + sizeof(time_t) + sizeof(uint16_t)
628 + newlen);
629 if(!newd)
630 return NULL;
631 ck->entry.data = newd;
632 newd->ttl = 0; /* 0 for synthesized CNAME TTL */
633 newd->count = 1;
634 newd->rrsig_count = 0;
635 newd->trust = rrset_trust_ans_noAA;
636 newd->rr_len = (size_t*)((uint8_t*)newd +
637 sizeof(struct packed_rrset_data));
638 newd->rr_len[0] = newlen + sizeof(uint16_t);
639 packed_rrset_ptr_fixup(newd);
640 newd->rr_ttl[0] = newd->ttl;
641 msg->rep->ttl = newd->ttl;
642 msg->rep->prefetch_ttl = PREFETCH_TTL_CALC(newd->ttl);
643 sldns_write_uint16(newd->rr_data[0], newlen);
644 memmove(newd->rr_data[0] + sizeof(uint16_t), newname, newlen);
645 msg->rep->an_numrrsets ++;
646 msg->rep->rrset_count ++;
647 return msg;
648 }
649
650 /** Fill TYPE_ANY response with some data from cache */
651 static struct dns_msg*
fill_any(struct module_env * env,uint8_t * qname,size_t qnamelen,uint16_t qtype,uint16_t qclass,struct regional * region)652 fill_any(struct module_env* env,
653 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
654 struct regional* region)
655 {
656 time_t now = *env->now;
657 struct dns_msg* msg = NULL;
658 uint16_t lookup[] = {LDNS_RR_TYPE_A, LDNS_RR_TYPE_AAAA,
659 LDNS_RR_TYPE_MX, LDNS_RR_TYPE_SOA, LDNS_RR_TYPE_NS,
660 LDNS_RR_TYPE_DNAME, 0};
661 int i, num=6; /* number of RR types to look up */
662 log_assert(lookup[num] == 0);
663
664 for(i=0; i<num; i++) {
665 /* look up this RR for inclusion in type ANY response */
666 struct ub_packed_rrset_key* rrset = rrset_cache_lookup(
667 env->rrset_cache, qname, qnamelen, lookup[i],
668 qclass, 0, now, 0);
669 struct packed_rrset_data *d;
670 if(!rrset)
671 continue;
672
673 /* only if rrset from answer section */
674 d = (struct packed_rrset_data*)rrset->entry.data;
675 if(d->trust == rrset_trust_add_noAA ||
676 d->trust == rrset_trust_auth_noAA ||
677 d->trust == rrset_trust_add_AA ||
678 d->trust == rrset_trust_auth_AA) {
679 lock_rw_unlock(&rrset->entry.lock);
680 continue;
681 }
682
683 /* create msg if none */
684 if(!msg) {
685 msg = dns_msg_create(qname, qnamelen, qtype, qclass,
686 region, (size_t)(num-i));
687 if(!msg) {
688 lock_rw_unlock(&rrset->entry.lock);
689 return NULL;
690 }
691 }
692
693 /* add RRset to response */
694 if(!dns_msg_ansadd(msg, region, rrset, now)) {
695 lock_rw_unlock(&rrset->entry.lock);
696 return NULL;
697 }
698 lock_rw_unlock(&rrset->entry.lock);
699 }
700 return msg;
701 }
702
703 struct dns_msg*
dns_cache_lookup(struct module_env * env,uint8_t * qname,size_t qnamelen,uint16_t qtype,uint16_t qclass,uint16_t flags,struct regional * region,struct regional * scratch)704 dns_cache_lookup(struct module_env* env,
705 uint8_t* qname, size_t qnamelen, uint16_t qtype, uint16_t qclass,
706 uint16_t flags, struct regional* region, struct regional* scratch)
707 {
708 struct lruhash_entry* e;
709 struct query_info k;
710 hashvalue_t h;
711 time_t now = *env->now;
712 struct ub_packed_rrset_key* rrset;
713
714 /* lookup first, this has both NXdomains and ANSWER responses */
715 k.qname = qname;
716 k.qname_len = qnamelen;
717 k.qtype = qtype;
718 k.qclass = qclass;
719 h = query_info_hash(&k, flags);
720 e = slabhash_lookup(env->msg_cache, h, &k, 0);
721 if(e) {
722 struct msgreply_entry* key = (struct msgreply_entry*)e->key;
723 struct reply_info* data = (struct reply_info*)e->data;
724 struct dns_msg* msg = tomsg(env, &key->key, data, region, now,
725 scratch);
726 if(msg) {
727 lock_rw_unlock(&e->lock);
728 return msg;
729 }
730 /* could be msg==NULL; due to TTL or not all rrsets available */
731 lock_rw_unlock(&e->lock);
732 }
733
734 /* see if a DNAME exists. Checked for first, to enforce that DNAMEs
735 * are more important, the CNAME is resynthesized and thus
736 * consistent with the DNAME */
737 if( (rrset=find_closest_of_type(env, qname, qnamelen, qclass, now,
738 LDNS_RR_TYPE_DNAME, 1))) {
739 /* synthesize a DNAME+CNAME message based on this */
740 struct dns_msg* msg = synth_dname_msg(rrset, region, now, &k);
741 if(msg) {
742 lock_rw_unlock(&rrset->entry.lock);
743 return msg;
744 }
745 lock_rw_unlock(&rrset->entry.lock);
746 }
747
748 /* see if we have CNAME for this domain,
749 * but not for DS records (which are part of the parent) */
750 if( qtype != LDNS_RR_TYPE_DS &&
751 (rrset=rrset_cache_lookup(env->rrset_cache, qname, qnamelen,
752 LDNS_RR_TYPE_CNAME, qclass, 0, now, 0))) {
753 struct dns_msg* msg = rrset_msg(rrset, region, now, &k);
754 if(msg) {
755 lock_rw_unlock(&rrset->entry.lock);
756 return msg;
757 }
758 lock_rw_unlock(&rrset->entry.lock);
759 }
760
761 /* construct DS, DNSKEY, DLV messages from rrset cache. */
762 if((qtype == LDNS_RR_TYPE_DS || qtype == LDNS_RR_TYPE_DNSKEY ||
763 qtype == LDNS_RR_TYPE_DLV) &&
764 (rrset=rrset_cache_lookup(env->rrset_cache, qname, qnamelen,
765 qtype, qclass, 0, now, 0))) {
766 /* if the rrset is from the additional section, and the
767 * signatures have fallen off, then do not synthesize a msg
768 * instead, allow a full query for signed results to happen.
769 * Forego all rrset data from additional section, because
770 * some signatures may not be present and cause validation
771 * failure.
772 */
773 struct packed_rrset_data *d = (struct packed_rrset_data*)
774 rrset->entry.data;
775 if(d->trust != rrset_trust_add_noAA &&
776 d->trust != rrset_trust_add_AA &&
777 (qtype == LDNS_RR_TYPE_DS ||
778 (d->trust != rrset_trust_auth_noAA
779 && d->trust != rrset_trust_auth_AA) )) {
780 struct dns_msg* msg = rrset_msg(rrset, region, now, &k);
781 if(msg) {
782 lock_rw_unlock(&rrset->entry.lock);
783 return msg;
784 }
785 }
786 lock_rw_unlock(&rrset->entry.lock);
787 }
788
789 /* stop downwards cache search on NXDOMAIN.
790 * Empty nonterminals are NOERROR, so an NXDOMAIN for foo
791 * means bla.foo also does not exist. The DNSSEC proofs are
792 * the same. We search upwards for NXDOMAINs. */
793 if(env->cfg->harden_below_nxdomain)
794 while(!dname_is_root(k.qname)) {
795 dname_remove_label(&k.qname, &k.qname_len);
796 h = query_info_hash(&k, flags);
797 e = slabhash_lookup(env->msg_cache, h, &k, 0);
798 if(e) {
799 struct reply_info* data = (struct reply_info*)e->data;
800 struct dns_msg* msg;
801 if(FLAGS_GET_RCODE(data->flags) == LDNS_RCODE_NXDOMAIN
802 && data->security == sec_status_secure
803 && (msg=tomsg(env, &k, data, region, now, scratch))){
804 lock_rw_unlock(&e->lock);
805 msg->qinfo.qname=qname;
806 msg->qinfo.qname_len=qnamelen;
807 /* check that DNSSEC really works out */
808 msg->rep->security = sec_status_unchecked;
809 return msg;
810 }
811 lock_rw_unlock(&e->lock);
812 }
813 }
814
815 /* fill common RR types for ANY response to avoid requery */
816 if(qtype == LDNS_RR_TYPE_ANY) {
817 return fill_any(env, qname, qnamelen, qtype, qclass, region);
818 }
819
820 return NULL;
821 }
822
823 int
dns_cache_store(struct module_env * env,struct query_info * msgqinf,struct reply_info * msgrep,int is_referral,time_t leeway,int pside,struct regional * region,uint16_t flags)824 dns_cache_store(struct module_env* env, struct query_info* msgqinf,
825 struct reply_info* msgrep, int is_referral, time_t leeway, int pside,
826 struct regional* region, uint16_t flags)
827 {
828 struct reply_info* rep = NULL;
829 /* alloc, malloc properly (not in region, like msg is) */
830 rep = reply_info_copy(msgrep, env->alloc, NULL);
831 if(!rep)
832 return 0;
833 /* ttl must be relative ;i.e. 0..86400 not time(0)+86400.
834 * the env->now is added to message and RRsets in this routine. */
835 /* the leeway is used to invalidate other rrsets earlier */
836
837 if(is_referral) {
838 /* store rrsets */
839 struct rrset_ref ref;
840 size_t i;
841 for(i=0; i<rep->rrset_count; i++) {
842 packed_rrset_ttl_add((struct packed_rrset_data*)
843 rep->rrsets[i]->entry.data, *env->now);
844 ref.key = rep->rrsets[i];
845 ref.id = rep->rrsets[i]->id;
846 /*ignore ret: it was in the cache, ref updated */
847 /* no leeway for typeNS */
848 (void)rrset_cache_update(env->rrset_cache, &ref,
849 env->alloc, *env->now +
850 ((ntohs(ref.key->rk.type)==LDNS_RR_TYPE_NS
851 && !pside) ? 0:leeway));
852 }
853 free(rep);
854 return 1;
855 } else {
856 /* store msg, and rrsets */
857 struct query_info qinf;
858 hashvalue_t h;
859
860 qinf = *msgqinf;
861 qinf.qname = memdup(msgqinf->qname, msgqinf->qname_len);
862 if(!qinf.qname) {
863 reply_info_parsedelete(rep, env->alloc);
864 return 0;
865 }
866 /* fixup flags to be sensible for a reply based on the cache */
867 /* this module means that RA is available. It is an answer QR.
868 * Not AA from cache. Not CD in cache (depends on client bit). */
869 rep->flags |= (BIT_RA | BIT_QR);
870 rep->flags &= ~(BIT_AA | BIT_CD);
871 h = query_info_hash(&qinf, flags);
872 dns_cache_store_msg(env, &qinf, h, rep, leeway, pside, msgrep,
873 region);
874 /* qname is used inside query_info_entrysetup, and set to
875 * NULL. If it has not been used, free it. free(0) is safe. */
876 free(qinf.qname);
877 }
878 return 1;
879 }
880
881 int
dns_cache_prefetch_adjust(struct module_env * env,struct query_info * qinfo,time_t adjust,uint16_t flags)882 dns_cache_prefetch_adjust(struct module_env* env, struct query_info* qinfo,
883 time_t adjust, uint16_t flags)
884 {
885 struct msgreply_entry* msg;
886 msg = msg_cache_lookup(env, qinfo->qname, qinfo->qname_len,
887 qinfo->qtype, qinfo->qclass, flags, *env->now, 1);
888 if(msg) {
889 struct reply_info* rep = (struct reply_info*)msg->entry.data;
890 if(rep) {
891 rep->prefetch_ttl += adjust;
892 lock_rw_unlock(&msg->entry.lock);
893 return 1;
894 }
895 lock_rw_unlock(&msg->entry.lock);
896 }
897 return 0;
898 }
899