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322345fd LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2014 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
9 | under the terms of the GNU Lesser General Public License as published by | |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
11 | (at your option) any later version. | |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
16 | Lesser General Public License for more details. | |
17 | ||
18 | You should have received a copy of the GNU Lesser General Public License | |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. | |
20 | ***/ | |
21 | ||
b5efdb8a | 22 | #include "alloc-util.h" |
58db254a | 23 | #include "dns-domain.h" |
02c2857b | 24 | #include "resolved-dns-answer.h" |
322345fd | 25 | #include "resolved-dns-cache.h" |
7e8e0422 | 26 | #include "resolved-dns-packet.h" |
58db254a | 27 | #include "string-util.h" |
322345fd | 28 | |
6af47493 LP |
29 | /* Never cache more than 4K entries. RFC 1536, Section 5 suggests to |
30 | * leave DNS caches unbounded, but that's crazy. */ | |
d98e5504 | 31 | #define CACHE_MAX 4096 |
cbd4560e | 32 | |
d98e5504 LP |
33 | /* We never keep any item longer than 2h in our cache */ |
34 | #define CACHE_TTL_MAX_USEC (2 * USEC_PER_HOUR) | |
322345fd | 35 | |
623a4c97 LP |
36 | typedef enum DnsCacheItemType DnsCacheItemType; |
37 | typedef struct DnsCacheItem DnsCacheItem; | |
38 | ||
39 | enum DnsCacheItemType { | |
40 | DNS_CACHE_POSITIVE, | |
41 | DNS_CACHE_NODATA, | |
42 | DNS_CACHE_NXDOMAIN, | |
43 | }; | |
44 | ||
45 | struct DnsCacheItem { | |
d2579eec | 46 | DnsCacheItemType type; |
623a4c97 LP |
47 | DnsResourceKey *key; |
48 | DnsResourceRecord *rr; | |
d2579eec | 49 | |
623a4c97 | 50 | usec_t until; |
d2579eec LP |
51 | bool authenticated:1; |
52 | bool shared_owner:1; | |
53 | ||
a4076574 LP |
54 | int owner_family; |
55 | union in_addr_union owner_address; | |
d2579eec LP |
56 | |
57 | unsigned prioq_idx; | |
623a4c97 LP |
58 | LIST_FIELDS(DnsCacheItem, by_key); |
59 | }; | |
60 | ||
322345fd LP |
61 | static void dns_cache_item_free(DnsCacheItem *i) { |
62 | if (!i) | |
63 | return; | |
64 | ||
65 | dns_resource_record_unref(i->rr); | |
7e8e0422 | 66 | dns_resource_key_unref(i->key); |
322345fd LP |
67 | free(i); |
68 | } | |
69 | ||
70 | DEFINE_TRIVIAL_CLEANUP_FUNC(DnsCacheItem*, dns_cache_item_free); | |
71 | ||
39963f11 | 72 | static void dns_cache_item_unlink_and_free(DnsCache *c, DnsCacheItem *i) { |
322345fd LP |
73 | DnsCacheItem *first; |
74 | ||
75 | assert(c); | |
76 | ||
77 | if (!i) | |
78 | return; | |
79 | ||
7e8e0422 LP |
80 | first = hashmap_get(c->by_key, i->key); |
81 | LIST_REMOVE(by_key, first, i); | |
322345fd LP |
82 | |
83 | if (first) | |
7e8e0422 | 84 | assert_se(hashmap_replace(c->by_key, first->key, first) >= 0); |
322345fd | 85 | else |
7e8e0422 | 86 | hashmap_remove(c->by_key, i->key); |
322345fd | 87 | |
7e8e0422 | 88 | prioq_remove(c->by_expiry, i, &i->prioq_idx); |
322345fd LP |
89 | |
90 | dns_cache_item_free(i); | |
91 | } | |
92 | ||
f5bdeb01 LP |
93 | static bool dns_cache_remove_by_rr(DnsCache *c, DnsResourceRecord *rr) { |
94 | DnsCacheItem *first, *i; | |
95 | int r; | |
96 | ||
97 | first = hashmap_get(c->by_key, rr->key); | |
98 | LIST_FOREACH(by_key, i, first) { | |
99 | r = dns_resource_record_equal(i->rr, rr); | |
100 | if (r < 0) | |
101 | return r; | |
102 | if (r > 0) { | |
39963f11 | 103 | dns_cache_item_unlink_and_free(c, i); |
f5bdeb01 LP |
104 | return true; |
105 | } | |
106 | } | |
107 | ||
108 | return false; | |
109 | } | |
110 | ||
2dda578f | 111 | static bool dns_cache_remove_by_key(DnsCache *c, DnsResourceKey *key) { |
1f97052f | 112 | DnsCacheItem *first, *i, *n; |
322345fd LP |
113 | |
114 | assert(c); | |
115 | assert(key); | |
116 | ||
1f97052f LP |
117 | first = hashmap_remove(c->by_key, key); |
118 | if (!first) | |
119 | return false; | |
120 | ||
121 | LIST_FOREACH_SAFE(by_key, i, n, first) { | |
122 | prioq_remove(c->by_expiry, i, &i->prioq_idx); | |
123 | dns_cache_item_free(i); | |
6b34a6c9 TG |
124 | } |
125 | ||
1f97052f | 126 | return true; |
322345fd LP |
127 | } |
128 | ||
ef9a3e3c LP |
129 | void dns_cache_flush(DnsCache *c) { |
130 | DnsResourceKey *key; | |
131 | ||
132 | assert(c); | |
133 | ||
134 | while ((key = hashmap_first_key(c->by_key))) | |
2dda578f | 135 | dns_cache_remove_by_key(c, key); |
ef9a3e3c LP |
136 | |
137 | assert(hashmap_size(c->by_key) == 0); | |
138 | assert(prioq_size(c->by_expiry) == 0); | |
139 | ||
140 | c->by_key = hashmap_free(c->by_key); | |
141 | c->by_expiry = prioq_free(c->by_expiry); | |
142 | } | |
143 | ||
322345fd LP |
144 | static void dns_cache_make_space(DnsCache *c, unsigned add) { |
145 | assert(c); | |
146 | ||
147 | if (add <= 0) | |
148 | return; | |
149 | ||
150 | /* Makes space for n new entries. Note that we actually allow | |
151 | * the cache to grow beyond CACHE_MAX, but only when we shall | |
152 | * add more RRs to the cache than CACHE_MAX at once. In that | |
153 | * case the cache will be emptied completely otherwise. */ | |
154 | ||
155 | for (;;) { | |
faa133f3 | 156 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; |
322345fd LP |
157 | DnsCacheItem *i; |
158 | ||
7e8e0422 | 159 | if (prioq_size(c->by_expiry) <= 0) |
322345fd LP |
160 | break; |
161 | ||
7e8e0422 | 162 | if (prioq_size(c->by_expiry) + add < CACHE_MAX) |
322345fd LP |
163 | break; |
164 | ||
7e8e0422 | 165 | i = prioq_peek(c->by_expiry); |
cbd4560e LP |
166 | assert(i); |
167 | ||
faa133f3 | 168 | /* Take an extra reference to the key so that it |
cbd4560e | 169 | * doesn't go away in the middle of the remove call */ |
7e8e0422 | 170 | key = dns_resource_key_ref(i->key); |
2dda578f | 171 | dns_cache_remove_by_key(c, key); |
322345fd LP |
172 | } |
173 | } | |
174 | ||
175 | void dns_cache_prune(DnsCache *c) { | |
176 | usec_t t = 0; | |
177 | ||
178 | assert(c); | |
179 | ||
180 | /* Remove all entries that are past their TTL */ | |
181 | ||
182 | for (;;) { | |
183 | DnsCacheItem *i; | |
322345fd | 184 | |
7e8e0422 | 185 | i = prioq_peek(c->by_expiry); |
322345fd LP |
186 | if (!i) |
187 | break; | |
188 | ||
322345fd | 189 | if (t <= 0) |
240b589b | 190 | t = now(clock_boottime_or_monotonic()); |
322345fd | 191 | |
7e8e0422 | 192 | if (i->until > t) |
322345fd LP |
193 | break; |
194 | ||
d2579eec LP |
195 | /* Depending whether this is an mDNS shared entry |
196 | * either remove only this one RR or the whole | |
197 | * RRset */ | |
198 | if (i->shared_owner) | |
39963f11 | 199 | dns_cache_item_unlink_and_free(c, i); |
d2579eec LP |
200 | else { |
201 | _cleanup_(dns_resource_key_unrefp) DnsResourceKey *key = NULL; | |
202 | ||
203 | /* Take an extra reference to the key so that it | |
204 | * doesn't go away in the middle of the remove call */ | |
205 | key = dns_resource_key_ref(i->key); | |
2dda578f | 206 | dns_cache_remove_by_key(c, key); |
d2579eec | 207 | } |
322345fd LP |
208 | } |
209 | } | |
210 | ||
211 | static int dns_cache_item_prioq_compare_func(const void *a, const void *b) { | |
322345fd LP |
212 | const DnsCacheItem *x = a, *y = b; |
213 | ||
7e8e0422 | 214 | if (x->until < y->until) |
322345fd | 215 | return -1; |
7e8e0422 | 216 | if (x->until > y->until) |
322345fd LP |
217 | return 1; |
218 | return 0; | |
219 | } | |
220 | ||
623a4c97 | 221 | static int dns_cache_init(DnsCache *c) { |
7e8e0422 LP |
222 | int r; |
223 | ||
623a4c97 LP |
224 | assert(c); |
225 | ||
7e8e0422 LP |
226 | r = prioq_ensure_allocated(&c->by_expiry, dns_cache_item_prioq_compare_func); |
227 | if (r < 0) | |
228 | return r; | |
229 | ||
d5099efc | 230 | r = hashmap_ensure_allocated(&c->by_key, &dns_resource_key_hash_ops); |
7e8e0422 LP |
231 | if (r < 0) |
232 | return r; | |
233 | ||
234 | return r; | |
235 | } | |
236 | ||
237 | static int dns_cache_link_item(DnsCache *c, DnsCacheItem *i) { | |
238 | DnsCacheItem *first; | |
239 | int r; | |
240 | ||
322345fd LP |
241 | assert(c); |
242 | assert(i); | |
322345fd | 243 | |
7e8e0422 LP |
244 | r = prioq_put(c->by_expiry, i, &i->prioq_idx); |
245 | if (r < 0) | |
246 | return r; | |
322345fd | 247 | |
7e8e0422 LP |
248 | first = hashmap_get(c->by_key, i->key); |
249 | if (first) { | |
250 | LIST_PREPEND(by_key, first, i); | |
251 | assert_se(hashmap_replace(c->by_key, first->key, first) >= 0); | |
252 | } else { | |
253 | r = hashmap_put(c->by_key, i->key, i); | |
254 | if (r < 0) { | |
255 | prioq_remove(c->by_expiry, i, &i->prioq_idx); | |
256 | return r; | |
257 | } | |
322345fd LP |
258 | } |
259 | ||
7e8e0422 | 260 | return 0; |
322345fd LP |
261 | } |
262 | ||
faa133f3 LP |
263 | static DnsCacheItem* dns_cache_get(DnsCache *c, DnsResourceRecord *rr) { |
264 | DnsCacheItem *i; | |
265 | ||
266 | assert(c); | |
267 | assert(rr); | |
268 | ||
7e8e0422 | 269 | LIST_FOREACH(by_key, i, hashmap_get(c->by_key, rr->key)) |
3ef77d04 | 270 | if (i->rr && dns_resource_record_equal(i->rr, rr) > 0) |
faa133f3 LP |
271 | return i; |
272 | ||
273 | return NULL; | |
274 | } | |
275 | ||
d3760be0 | 276 | static usec_t calculate_until(DnsResourceRecord *rr, uint32_t nsec_ttl, usec_t timestamp, bool use_soa_minimum) { |
b211dc7e LP |
277 | uint32_t ttl; |
278 | usec_t u; | |
ee3d6aff LP |
279 | |
280 | assert(rr); | |
281 | ||
d3760be0 | 282 | ttl = MIN(rr->ttl, nsec_ttl); |
b211dc7e LP |
283 | if (rr->key->type == DNS_TYPE_SOA && use_soa_minimum) { |
284 | /* If this is a SOA RR, and it is requested, clamp to | |
285 | * the SOA's minimum field. This is used when we do | |
286 | * negative caching, to determine the TTL for the | |
287 | * negative caching entry. See RFC 2308, Section | |
288 | * 5. */ | |
ee3d6aff | 289 | |
b211dc7e LP |
290 | if (ttl > rr->soa.minimum) |
291 | ttl = rr->soa.minimum; | |
292 | } | |
293 | ||
294 | u = ttl * USEC_PER_SEC; | |
295 | if (u > CACHE_TTL_MAX_USEC) | |
296 | u = CACHE_TTL_MAX_USEC; | |
ee3d6aff LP |
297 | |
298 | if (rr->expiry != USEC_INFINITY) { | |
299 | usec_t left; | |
300 | ||
b211dc7e LP |
301 | /* Make use of the DNSSEC RRSIG expiry info, if we |
302 | * have it */ | |
ee3d6aff LP |
303 | |
304 | left = LESS_BY(rr->expiry, now(CLOCK_REALTIME)); | |
b211dc7e LP |
305 | if (u > left) |
306 | u = left; | |
ee3d6aff LP |
307 | } |
308 | ||
b211dc7e | 309 | return timestamp + u; |
ee3d6aff LP |
310 | } |
311 | ||
d2579eec LP |
312 | static void dns_cache_item_update_positive( |
313 | DnsCache *c, | |
314 | DnsCacheItem *i, | |
315 | DnsResourceRecord *rr, | |
316 | bool authenticated, | |
317 | bool shared_owner, | |
318 | usec_t timestamp, | |
319 | int owner_family, | |
320 | const union in_addr_union *owner_address) { | |
321 | ||
7e8e0422 LP |
322 | assert(c); |
323 | assert(i); | |
324 | assert(rr); | |
d2579eec | 325 | assert(owner_address); |
7e8e0422 LP |
326 | |
327 | i->type = DNS_CACHE_POSITIVE; | |
328 | ||
ece174c5 | 329 | if (!i->by_key_prev) |
7e8e0422 LP |
330 | /* We are the first item in the list, we need to |
331 | * update the key used in the hashmap */ | |
332 | ||
333 | assert_se(hashmap_replace(c->by_key, rr->key, i) >= 0); | |
7e8e0422 LP |
334 | |
335 | dns_resource_record_ref(rr); | |
336 | dns_resource_record_unref(i->rr); | |
337 | i->rr = rr; | |
338 | ||
339 | dns_resource_key_unref(i->key); | |
340 | i->key = dns_resource_key_ref(rr->key); | |
341 | ||
d3760be0 | 342 | i->until = calculate_until(rr, (uint32_t) -1, timestamp, false); |
d2579eec LP |
343 | i->authenticated = authenticated; |
344 | i->shared_owner = shared_owner; | |
345 | ||
346 | i->owner_family = owner_family; | |
347 | i->owner_address = *owner_address; | |
7e8e0422 LP |
348 | |
349 | prioq_reshuffle(c->by_expiry, i, &i->prioq_idx); | |
350 | } | |
351 | ||
a4076574 LP |
352 | static int dns_cache_put_positive( |
353 | DnsCache *c, | |
354 | DnsResourceRecord *rr, | |
931851e8 | 355 | bool authenticated, |
d2579eec | 356 | bool shared_owner, |
a4076574 LP |
357 | usec_t timestamp, |
358 | int owner_family, | |
359 | const union in_addr_union *owner_address) { | |
360 | ||
322345fd | 361 | _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL; |
6b34a6c9 | 362 | _cleanup_free_ char *key_str = NULL; |
7e8e0422 | 363 | DnsCacheItem *existing; |
a257f9d4 | 364 | int r, k; |
322345fd LP |
365 | |
366 | assert(c); | |
367 | assert(rr); | |
a4076574 | 368 | assert(owner_address); |
322345fd | 369 | |
222148b6 LP |
370 | /* Never cache pseudo RRs */ |
371 | if (dns_class_is_pseudo(rr->key->class)) | |
372 | return 0; | |
373 | if (dns_type_is_pseudo(rr->key->type)) | |
374 | return 0; | |
375 | ||
f5bdeb01 | 376 | /* New TTL is 0? Delete this specific entry... */ |
322345fd | 377 | if (rr->ttl <= 0) { |
f5bdeb01 | 378 | k = dns_cache_remove_by_rr(c, rr); |
6b34a6c9 | 379 | |
a257f9d4 TG |
380 | if (log_get_max_level() >= LOG_DEBUG) { |
381 | r = dns_resource_key_to_string(rr->key, &key_str); | |
382 | if (r < 0) | |
383 | return r; | |
384 | ||
385 | if (k > 0) | |
386 | log_debug("Removed zero TTL entry from cache: %s", key_str); | |
387 | else | |
388 | log_debug("Not caching zero TTL cache entry: %s", key_str); | |
389 | } | |
6b34a6c9 | 390 | |
322345fd LP |
391 | return 0; |
392 | } | |
393 | ||
d2579eec | 394 | /* Entry exists already? Update TTL, timestamp and owner*/ |
322345fd LP |
395 | existing = dns_cache_get(c, rr); |
396 | if (existing) { | |
d2579eec LP |
397 | dns_cache_item_update_positive( |
398 | c, | |
399 | existing, | |
400 | rr, | |
401 | authenticated, | |
402 | shared_owner, | |
403 | timestamp, | |
404 | owner_family, | |
405 | owner_address); | |
322345fd LP |
406 | return 0; |
407 | } | |
408 | ||
409 | /* Otherwise, add the new RR */ | |
623a4c97 | 410 | r = dns_cache_init(c); |
322345fd LP |
411 | if (r < 0) |
412 | return r; | |
413 | ||
7e8e0422 LP |
414 | dns_cache_make_space(c, 1); |
415 | ||
416 | i = new0(DnsCacheItem, 1); | |
417 | if (!i) | |
418 | return -ENOMEM; | |
419 | ||
420 | i->type = DNS_CACHE_POSITIVE; | |
421 | i->key = dns_resource_key_ref(rr->key); | |
422 | i->rr = dns_resource_record_ref(rr); | |
d3760be0 | 423 | i->until = calculate_until(rr, (uint32_t) -1, timestamp, false); |
d2579eec LP |
424 | i->authenticated = authenticated; |
425 | i->shared_owner = shared_owner; | |
a4076574 LP |
426 | i->owner_family = owner_family; |
427 | i->owner_address = *owner_address; | |
d2579eec | 428 | i->prioq_idx = PRIOQ_IDX_NULL; |
7e8e0422 LP |
429 | |
430 | r = dns_cache_link_item(c, i); | |
431 | if (r < 0) | |
432 | return r; | |
433 | ||
a257f9d4 TG |
434 | if (log_get_max_level() >= LOG_DEBUG) { |
435 | r = dns_resource_key_to_string(i->key, &key_str); | |
436 | if (r < 0) | |
437 | return r; | |
6b34a6c9 | 438 | |
d2579eec | 439 | log_debug("Added positive cache entry for %s", key_str); |
a257f9d4 | 440 | } |
6b34a6c9 | 441 | |
7e8e0422 LP |
442 | i = NULL; |
443 | return 0; | |
444 | } | |
445 | ||
a4076574 LP |
446 | static int dns_cache_put_negative( |
447 | DnsCache *c, | |
448 | DnsResourceKey *key, | |
449 | int rcode, | |
931851e8 | 450 | bool authenticated, |
d3760be0 | 451 | uint32_t nsec_ttl, |
a4076574 | 452 | usec_t timestamp, |
b211dc7e | 453 | DnsResourceRecord *soa, |
a4076574 LP |
454 | int owner_family, |
455 | const union in_addr_union *owner_address) { | |
456 | ||
7e8e0422 | 457 | _cleanup_(dns_cache_item_freep) DnsCacheItem *i = NULL; |
6b34a6c9 | 458 | _cleanup_free_ char *key_str = NULL; |
7e8e0422 LP |
459 | int r; |
460 | ||
461 | assert(c); | |
462 | assert(key); | |
b211dc7e | 463 | assert(soa); |
a4076574 | 464 | assert(owner_address); |
7e8e0422 | 465 | |
98b6be77 LP |
466 | /* Never cache pseudo RR keys. DNS_TYPE_ANY is particularly |
467 | * important to filter out as we use this as a pseudo-type for | |
468 | * NXDOMAIN entries */ | |
222148b6 | 469 | if (dns_class_is_pseudo(key->class)) |
ddf16339 | 470 | return 0; |
c33be4a6 | 471 | if (dns_type_is_pseudo(key->type)) |
ddf16339 | 472 | return 0; |
222148b6 | 473 | |
d3760be0 | 474 | if (nsec_ttl <= 0 || soa->soa.minimum <= 0 || soa->ttl <= 0) { |
a257f9d4 TG |
475 | if (log_get_max_level() >= LOG_DEBUG) { |
476 | r = dns_resource_key_to_string(key, &key_str); | |
477 | if (r < 0) | |
478 | return r; | |
6b34a6c9 | 479 | |
d3760be0 | 480 | log_debug("Not caching negative entry with zero SOA/NSEC/NSEC3 TTL: %s", key_str); |
a257f9d4 | 481 | } |
6b34a6c9 | 482 | |
95dd6257 | 483 | return 0; |
6b34a6c9 | 484 | } |
ddf16339 | 485 | |
7e8e0422 LP |
486 | if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN)) |
487 | return 0; | |
488 | ||
623a4c97 | 489 | r = dns_cache_init(c); |
322345fd LP |
490 | if (r < 0) |
491 | return r; | |
492 | ||
493 | dns_cache_make_space(c, 1); | |
494 | ||
495 | i = new0(DnsCacheItem, 1); | |
496 | if (!i) | |
497 | return -ENOMEM; | |
498 | ||
7e8e0422 | 499 | i->type = rcode == DNS_RCODE_SUCCESS ? DNS_CACHE_NODATA : DNS_CACHE_NXDOMAIN; |
d3760be0 | 500 | i->until = calculate_until(soa, nsec_ttl, timestamp, true); |
d2579eec | 501 | i->authenticated = authenticated; |
a4076574 LP |
502 | i->owner_family = owner_family; |
503 | i->owner_address = *owner_address; | |
d2579eec | 504 | i->prioq_idx = PRIOQ_IDX_NULL; |
322345fd | 505 | |
71e13669 TG |
506 | if (i->type == DNS_CACHE_NXDOMAIN) { |
507 | /* NXDOMAIN entries should apply equally to all types, so we use ANY as | |
508 | * a pseudo type for this purpose here. */ | |
509 | i->key = dns_resource_key_new(key->class, DNS_TYPE_ANY, DNS_RESOURCE_KEY_NAME(key)); | |
510 | if (!i->key) | |
511 | return -ENOMEM; | |
a5444ca9 LP |
512 | |
513 | /* Make sure to remove any previous entry for this | |
514 | * specific ANY key. (For non-ANY keys the cache data | |
515 | * is already cleared by the caller.) Note that we | |
516 | * don't bother removing positive or NODATA cache | |
517 | * items in this case, because it would either be slow | |
518 | * or require explicit indexing by name */ | |
519 | dns_cache_remove_by_key(c, key); | |
71e13669 TG |
520 | } else |
521 | i->key = dns_resource_key_ref(key); | |
522 | ||
7e8e0422 | 523 | r = dns_cache_link_item(c, i); |
322345fd LP |
524 | if (r < 0) |
525 | return r; | |
526 | ||
a257f9d4 TG |
527 | if (log_get_max_level() >= LOG_DEBUG) { |
528 | r = dns_resource_key_to_string(i->key, &key_str); | |
529 | if (r < 0) | |
530 | return r; | |
6b34a6c9 | 531 | |
a257f9d4 TG |
532 | log_debug("Added %s cache entry for %s", i->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN", key_str); |
533 | } | |
6b34a6c9 | 534 | |
322345fd | 535 | i = NULL; |
322345fd LP |
536 | return 0; |
537 | } | |
538 | ||
d2579eec LP |
539 | static void dns_cache_remove_previous( |
540 | DnsCache *c, | |
541 | DnsResourceKey *key, | |
542 | DnsAnswer *answer) { | |
543 | ||
544 | DnsResourceRecord *rr; | |
545 | DnsAnswerFlags flags; | |
546 | ||
547 | assert(c); | |
548 | ||
549 | /* First, if we were passed a key (i.e. on LLMNR/DNS, but | |
550 | * not on mDNS), delete all matching old RRs, so that we only | |
551 | * keep complete by_key in place. */ | |
552 | if (key) | |
2dda578f | 553 | dns_cache_remove_by_key(c, key); |
d2579eec LP |
554 | |
555 | /* Second, flush all entries matching the answer, unless this | |
556 | * is an RR that is explicitly marked to be "shared" between | |
557 | * peers (i.e. mDNS RRs without the flush-cache bit set). */ | |
558 | DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) { | |
559 | if ((flags & DNS_ANSWER_CACHEABLE) == 0) | |
560 | continue; | |
561 | ||
562 | if (flags & DNS_ANSWER_SHARED_OWNER) | |
563 | continue; | |
564 | ||
2dda578f | 565 | dns_cache_remove_by_key(c, rr->key); |
d2579eec LP |
566 | } |
567 | } | |
568 | ||
a4076574 LP |
569 | int dns_cache_put( |
570 | DnsCache *c, | |
8e427d9b | 571 | DnsResourceKey *key, |
a4076574 LP |
572 | int rcode, |
573 | DnsAnswer *answer, | |
931851e8 | 574 | bool authenticated, |
d3760be0 | 575 | uint32_t nsec_ttl, |
a4076574 LP |
576 | usec_t timestamp, |
577 | int owner_family, | |
578 | const union in_addr_union *owner_address) { | |
579 | ||
02c2857b | 580 | DnsResourceRecord *soa = NULL, *rr; |
105e1512 LP |
581 | DnsAnswerFlags flags; |
582 | unsigned cache_keys; | |
322345fd LP |
583 | int r; |
584 | ||
585 | assert(c); | |
d2579eec | 586 | assert(owner_address); |
322345fd | 587 | |
d2579eec | 588 | dns_cache_remove_previous(c, key, answer); |
0ec7c46e | 589 | |
ea207b63 | 590 | if (dns_answer_size(answer) <= 0) { |
a257f9d4 TG |
591 | if (log_get_max_level() >= LOG_DEBUG) { |
592 | _cleanup_free_ char *key_str = NULL; | |
c3cb6dc2 | 593 | |
a257f9d4 TG |
594 | r = dns_resource_key_to_string(key, &key_str); |
595 | if (r < 0) | |
596 | return r; | |
c3cb6dc2 | 597 | |
a257f9d4 TG |
598 | log_debug("Not caching negative entry without a SOA record: %s", key_str); |
599 | } | |
c3cb6dc2 | 600 | |
0ec7c46e | 601 | return 0; |
c3cb6dc2 | 602 | } |
0ec7c46e | 603 | |
7e8e0422 LP |
604 | /* We only care for positive replies and NXDOMAINs, on all |
605 | * other replies we will simply flush the respective entries, | |
606 | * and that's it */ | |
7e8e0422 LP |
607 | if (!IN_SET(rcode, DNS_RCODE_SUCCESS, DNS_RCODE_NXDOMAIN)) |
608 | return 0; | |
609 | ||
ea207b63 | 610 | cache_keys = dns_answer_size(answer); |
8e427d9b TG |
611 | if (key) |
612 | cache_keys ++; | |
eff91ee0 | 613 | |
7e8e0422 | 614 | /* Make some space for our new entries */ |
eff91ee0 | 615 | dns_cache_make_space(c, cache_keys); |
322345fd | 616 | |
7e8e0422 | 617 | if (timestamp <= 0) |
240b589b | 618 | timestamp = now(clock_boottime_or_monotonic()); |
322345fd | 619 | |
7e8e0422 | 620 | /* Second, add in positive entries for all contained RRs */ |
105e1512 LP |
621 | DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) { |
622 | if ((flags & DNS_ANSWER_CACHEABLE) == 0) | |
623 | continue; | |
624 | ||
d2579eec LP |
625 | r = dns_cache_put_positive( |
626 | c, | |
627 | rr, | |
628 | flags & DNS_ANSWER_AUTHENTICATED, | |
629 | flags & DNS_ANSWER_SHARED_OWNER, | |
630 | timestamp, | |
631 | owner_family, owner_address); | |
7e8e0422 LP |
632 | if (r < 0) |
633 | goto fail; | |
634 | } | |
635 | ||
d2579eec | 636 | if (!key) /* mDNS doesn't know negative caching, really */ |
eff91ee0 DM |
637 | return 0; |
638 | ||
8e427d9b | 639 | /* Third, add in negative entries if the key has no RR */ |
105e1512 | 640 | r = dns_answer_match_key(answer, key, NULL); |
8e427d9b TG |
641 | if (r < 0) |
642 | goto fail; | |
643 | if (r > 0) | |
644 | return 0; | |
7e8e0422 | 645 | |
5d27351f TG |
646 | /* But not if it has a matching CNAME/DNAME (the negative |
647 | * caching will be done on the canonical name, not on the | |
648 | * alias) */ | |
105e1512 | 649 | r = dns_answer_find_cname_or_dname(answer, key, NULL, NULL); |
5d27351f TG |
650 | if (r < 0) |
651 | goto fail; | |
652 | if (r > 0) | |
653 | return 0; | |
654 | ||
547973de LP |
655 | /* See https://tools.ietf.org/html/rfc2308, which say that a |
656 | * matching SOA record in the packet is used to to enable | |
657 | * negative caching. */ | |
fd009cd8 | 658 | r = dns_answer_find_soa(answer, key, &soa, &flags); |
8e427d9b TG |
659 | if (r < 0) |
660 | goto fail; | |
661 | if (r == 0) | |
662 | return 0; | |
7e8e0422 | 663 | |
fd009cd8 LP |
664 | /* Refuse using the SOA data if it is unsigned, but the key is |
665 | * signed */ | |
666 | if (authenticated && (flags & DNS_ANSWER_AUTHENTICATED) == 0) | |
667 | return 0; | |
668 | ||
d2579eec LP |
669 | r = dns_cache_put_negative( |
670 | c, | |
671 | key, | |
672 | rcode, | |
673 | authenticated, | |
d3760be0 | 674 | nsec_ttl, |
d2579eec | 675 | timestamp, |
b211dc7e | 676 | soa, |
d2579eec | 677 | owner_family, owner_address); |
8e427d9b TG |
678 | if (r < 0) |
679 | goto fail; | |
322345fd LP |
680 | |
681 | return 0; | |
682 | ||
683 | fail: | |
684 | /* Adding all RRs failed. Let's clean up what we already | |
685 | * added, just in case */ | |
686 | ||
8e427d9b | 687 | if (key) |
2dda578f | 688 | dns_cache_remove_by_key(c, key); |
eff91ee0 | 689 | |
105e1512 LP |
690 | DNS_ANSWER_FOREACH_FLAGS(rr, flags, answer) { |
691 | if ((flags & DNS_ANSWER_CACHEABLE) == 0) | |
692 | continue; | |
693 | ||
2dda578f | 694 | dns_cache_remove_by_key(c, rr->key); |
105e1512 | 695 | } |
322345fd LP |
696 | |
697 | return r; | |
698 | } | |
699 | ||
37da8931 | 700 | static DnsCacheItem *dns_cache_get_by_key_follow_cname_dname_nsec(DnsCache *c, DnsResourceKey *k) { |
58db254a LP |
701 | DnsCacheItem *i; |
702 | const char *n; | |
703 | int r; | |
5643c00a TG |
704 | |
705 | assert(c); | |
706 | assert(k); | |
707 | ||
58db254a LP |
708 | /* If we hit some OOM error, or suchlike, we don't care too |
709 | * much, after all this is just a cache */ | |
710 | ||
5643c00a | 711 | i = hashmap_get(c->by_key, k); |
d7ce6c94 | 712 | if (i) |
37da8931 LP |
713 | return i; |
714 | ||
715 | n = DNS_RESOURCE_KEY_NAME(k); | |
716 | ||
71e13669 TG |
717 | /* Check if we have an NXDOMAIN cache item for the name, notice that we use |
718 | * the pseudo-type ANY for NXDOMAIN cache items. */ | |
719 | i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_ANY, n)); | |
720 | if (i && i->type == DNS_CACHE_NXDOMAIN) | |
721 | return i; | |
722 | ||
d3c7e913 | 723 | if (dns_type_may_redirect(k->type)) { |
d7ce6c94 TG |
724 | /* Check if we have a CNAME record instead */ |
725 | i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_CNAME, n)); | |
726 | if (i) | |
727 | return i; | |
5643c00a | 728 | |
d7ce6c94 TG |
729 | /* OK, let's look for cached DNAME records. */ |
730 | for (;;) { | |
d7ce6c94 TG |
731 | if (isempty(n)) |
732 | return NULL; | |
733 | ||
734 | i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_DNAME, n)); | |
735 | if (i) | |
736 | return i; | |
58db254a | 737 | |
d7ce6c94 | 738 | /* Jump one label ahead */ |
950b692b | 739 | r = dns_name_parent(&n); |
d7ce6c94 TG |
740 | if (r <= 0) |
741 | return NULL; | |
742 | } | |
743 | } | |
5643c00a | 744 | |
950b692b | 745 | if (k->type != DNS_TYPE_NSEC) { |
d7ce6c94 TG |
746 | /* Check if we have an NSEC record instead for the name. */ |
747 | i = hashmap_get(c->by_key, &DNS_RESOURCE_KEY_CONST(k->class, DNS_TYPE_NSEC, n)); | |
58db254a LP |
748 | if (i) |
749 | return i; | |
58db254a LP |
750 | } |
751 | ||
752 | return NULL; | |
5643c00a TG |
753 | } |
754 | ||
931851e8 | 755 | int dns_cache_lookup(DnsCache *c, DnsResourceKey *key, int *rcode, DnsAnswer **ret, bool *authenticated) { |
faa133f3 | 756 | _cleanup_(dns_answer_unrefp) DnsAnswer *answer = NULL; |
f52e61da | 757 | unsigned n = 0; |
322345fd | 758 | int r; |
7e8e0422 | 759 | bool nxdomain = false; |
f52e61da | 760 | _cleanup_free_ char *key_str = NULL; |
931851e8 LP |
761 | DnsCacheItem *j, *first, *nsec = NULL; |
762 | bool have_authenticated = false, have_non_authenticated = false; | |
322345fd LP |
763 | |
764 | assert(c); | |
f52e61da | 765 | assert(key); |
623a4c97 | 766 | assert(rcode); |
faa133f3 | 767 | assert(ret); |
931851e8 | 768 | assert(authenticated); |
322345fd | 769 | |
f52e61da LP |
770 | if (key->type == DNS_TYPE_ANY || |
771 | key->class == DNS_CLASS_ANY) { | |
322345fd | 772 | |
931851e8 LP |
773 | /* If we have ANY lookups we don't use the cache, so |
774 | * that the caller refreshes via the network. */ | |
322345fd | 775 | |
a257f9d4 TG |
776 | if (log_get_max_level() >= LOG_DEBUG) { |
777 | r = dns_resource_key_to_string(key, &key_str); | |
778 | if (r < 0) | |
779 | return r; | |
6b34a6c9 | 780 | |
a257f9d4 TG |
781 | log_debug("Ignoring cache for ANY lookup: %s", key_str); |
782 | } | |
6b34a6c9 | 783 | |
a150ff5e LP |
784 | c->n_miss++; |
785 | ||
f52e61da LP |
786 | *ret = NULL; |
787 | *rcode = DNS_RCODE_SUCCESS; | |
788 | return 0; | |
789 | } | |
6b34a6c9 | 790 | |
37da8931 | 791 | first = dns_cache_get_by_key_follow_cname_dname_nsec(c, key); |
f52e61da LP |
792 | if (!first) { |
793 | /* If one question cannot be answered we need to refresh */ | |
ddf16339 | 794 | |
a257f9d4 TG |
795 | if (log_get_max_level() >= LOG_DEBUG) { |
796 | r = dns_resource_key_to_string(key, &key_str); | |
797 | if (r < 0) | |
798 | return r; | |
6b34a6c9 | 799 | |
a257f9d4 TG |
800 | log_debug("Cache miss for %s", key_str); |
801 | } | |
6b34a6c9 | 802 | |
a150ff5e LP |
803 | c->n_miss++; |
804 | ||
f52e61da LP |
805 | *ret = NULL; |
806 | *rcode = DNS_RCODE_SUCCESS; | |
807 | return 0; | |
808 | } | |
6b34a6c9 | 809 | |
f52e61da | 810 | LIST_FOREACH(by_key, j, first) { |
37da8931 LP |
811 | if (j->rr) { |
812 | if (j->rr->key->type == DNS_TYPE_NSEC) | |
931851e8 LP |
813 | nsec = j; |
814 | ||
f52e61da | 815 | n++; |
37da8931 | 816 | } else if (j->type == DNS_CACHE_NXDOMAIN) |
f52e61da | 817 | nxdomain = true; |
931851e8 LP |
818 | |
819 | if (j->authenticated) | |
820 | have_authenticated = true; | |
821 | else | |
822 | have_non_authenticated = true; | |
f52e61da | 823 | } |
6b34a6c9 | 824 | |
37da8931 | 825 | if (nsec && key->type != DNS_TYPE_NSEC) { |
a257f9d4 TG |
826 | if (log_get_max_level() >= LOG_DEBUG) { |
827 | r = dns_resource_key_to_string(key, &key_str); | |
828 | if (r < 0) | |
829 | return r; | |
830 | ||
831 | log_debug("NSEC NODATA cache hit for %s", key_str); | |
832 | } | |
37da8931 LP |
833 | |
834 | /* We only found an NSEC record that matches our name. | |
a257f9d4 | 835 | * If it says the type doesn't exist report |
37da8931 LP |
836 | * NODATA. Otherwise report a cache miss. */ |
837 | ||
838 | *ret = NULL; | |
839 | *rcode = DNS_RCODE_SUCCESS; | |
931851e8 | 840 | *authenticated = nsec->authenticated; |
37da8931 | 841 | |
a150ff5e LP |
842 | if (!bitmap_isset(nsec->rr->nsec.types, key->type) && |
843 | !bitmap_isset(nsec->rr->nsec.types, DNS_TYPE_CNAME) && | |
844 | !bitmap_isset(nsec->rr->nsec.types, DNS_TYPE_DNAME)) { | |
845 | c->n_hit++; | |
846 | return 1; | |
847 | } | |
848 | ||
849 | c->n_miss++; | |
850 | return 0; | |
37da8931 LP |
851 | } |
852 | ||
a257f9d4 TG |
853 | if (log_get_max_level() >= LOG_DEBUG) { |
854 | r = dns_resource_key_to_string(key, &key_str); | |
855 | if (r < 0) | |
856 | return r; | |
857 | ||
858 | log_debug("%s cache hit for %s", | |
859 | n > 0 ? "Positive" : | |
860 | nxdomain ? "NXDOMAIN" : "NODATA", | |
861 | key_str); | |
862 | } | |
faa133f3 | 863 | |
7e8e0422 | 864 | if (n <= 0) { |
a150ff5e LP |
865 | c->n_hit++; |
866 | ||
7e8e0422 LP |
867 | *ret = NULL; |
868 | *rcode = nxdomain ? DNS_RCODE_NXDOMAIN : DNS_RCODE_SUCCESS; | |
931851e8 | 869 | *authenticated = have_authenticated && !have_non_authenticated; |
7e8e0422 LP |
870 | return 1; |
871 | } | |
faa133f3 LP |
872 | |
873 | answer = dns_answer_new(n); | |
874 | if (!answer) | |
875 | return -ENOMEM; | |
322345fd | 876 | |
f52e61da LP |
877 | LIST_FOREACH(by_key, j, first) { |
878 | if (!j->rr) | |
879 | continue; | |
880 | ||
eed749cc | 881 | r = dns_answer_add(answer, j->rr, 0, j->authenticated ? DNS_ANSWER_AUTHENTICATED : 0); |
f52e61da LP |
882 | if (r < 0) |
883 | return r; | |
322345fd LP |
884 | } |
885 | ||
a150ff5e LP |
886 | c->n_hit++; |
887 | ||
faa133f3 | 888 | *ret = answer; |
7e8e0422 | 889 | *rcode = DNS_RCODE_SUCCESS; |
931851e8 | 890 | *authenticated = have_authenticated && !have_non_authenticated; |
faa133f3 LP |
891 | answer = NULL; |
892 | ||
893 | return n; | |
322345fd | 894 | } |
a4076574 LP |
895 | |
896 | int dns_cache_check_conflicts(DnsCache *cache, DnsResourceRecord *rr, int owner_family, const union in_addr_union *owner_address) { | |
897 | DnsCacheItem *i, *first; | |
898 | bool same_owner = true; | |
899 | ||
900 | assert(cache); | |
901 | assert(rr); | |
902 | ||
903 | dns_cache_prune(cache); | |
904 | ||
905 | /* See if there's a cache entry for the same key. If there | |
906 | * isn't there's no conflict */ | |
907 | first = hashmap_get(cache->by_key, rr->key); | |
908 | if (!first) | |
909 | return 0; | |
910 | ||
911 | /* See if the RR key is owned by the same owner, if so, there | |
912 | * isn't a conflict either */ | |
913 | LIST_FOREACH(by_key, i, first) { | |
914 | if (i->owner_family != owner_family || | |
915 | !in_addr_equal(owner_family, &i->owner_address, owner_address)) { | |
916 | same_owner = false; | |
917 | break; | |
918 | } | |
919 | } | |
920 | if (same_owner) | |
921 | return 0; | |
922 | ||
923 | /* See if there's the exact same RR in the cache. If yes, then | |
924 | * there's no conflict. */ | |
925 | if (dns_cache_get(cache, rr)) | |
926 | return 0; | |
927 | ||
928 | /* There's a conflict */ | |
929 | return 1; | |
930 | } | |
4d506d6b | 931 | |
7778dfff DM |
932 | int dns_cache_export_shared_to_packet(DnsCache *cache, DnsPacket *p) { |
933 | unsigned ancount = 0; | |
934 | Iterator iterator; | |
935 | DnsCacheItem *i; | |
936 | int r; | |
937 | ||
938 | assert(cache); | |
261f3673 | 939 | assert(p); |
7778dfff DM |
940 | |
941 | HASHMAP_FOREACH(i, cache->by_key, iterator) { | |
942 | DnsCacheItem *j; | |
943 | ||
944 | LIST_FOREACH(by_key, j, i) { | |
7778dfff DM |
945 | if (!j->rr) |
946 | continue; | |
947 | ||
d2579eec | 948 | if (!j->shared_owner) |
7778dfff DM |
949 | continue; |
950 | ||
951 | r = dns_packet_append_rr(p, j->rr, NULL, NULL); | |
261f3673 DM |
952 | if (r == -EMSGSIZE && p->protocol == DNS_PROTOCOL_MDNS) { |
953 | /* For mDNS, if we're unable to stuff all known answers into the given packet, | |
954 | * allocate a new one, push the RR into that one and link it to the current one. | |
955 | */ | |
956 | ||
957 | DNS_PACKET_HEADER(p)->ancount = htobe16(ancount); | |
958 | ancount = 0; | |
959 | ||
960 | r = dns_packet_new_query(&p->more, p->protocol, 0, true); | |
961 | if (r < 0) | |
962 | return r; | |
963 | ||
964 | /* continue with new packet */ | |
965 | p = p->more; | |
966 | r = dns_packet_append_rr(p, j->rr, NULL, NULL); | |
967 | } | |
968 | ||
7778dfff DM |
969 | if (r < 0) |
970 | return r; | |
971 | ||
972 | ancount ++; | |
973 | } | |
974 | } | |
975 | ||
976 | DNS_PACKET_HEADER(p)->ancount = htobe16(ancount); | |
977 | ||
978 | return 0; | |
979 | } | |
980 | ||
4d506d6b LP |
981 | void dns_cache_dump(DnsCache *cache, FILE *f) { |
982 | Iterator iterator; | |
983 | DnsCacheItem *i; | |
984 | int r; | |
985 | ||
986 | if (!cache) | |
987 | return; | |
988 | ||
989 | if (!f) | |
990 | f = stdout; | |
991 | ||
992 | HASHMAP_FOREACH(i, cache->by_key, iterator) { | |
993 | DnsCacheItem *j; | |
994 | ||
995 | LIST_FOREACH(by_key, j, i) { | |
4d506d6b LP |
996 | |
997 | fputc('\t', f); | |
998 | ||
999 | if (j->rr) { | |
7b50eb2e LP |
1000 | const char *t; |
1001 | t = dns_resource_record_to_string(j->rr); | |
1002 | if (!t) { | |
4d506d6b LP |
1003 | log_oom(); |
1004 | continue; | |
1005 | } | |
1006 | ||
1007 | fputs(t, f); | |
1008 | fputc('\n', f); | |
1009 | } else { | |
7b50eb2e LP |
1010 | _cleanup_free_ char *z = NULL; |
1011 | r = dns_resource_key_to_string(j->key, &z); | |
4d506d6b LP |
1012 | if (r < 0) { |
1013 | log_oom(); | |
1014 | continue; | |
1015 | } | |
1016 | ||
7b50eb2e | 1017 | fputs(z, f); |
4d506d6b LP |
1018 | fputs(" -- ", f); |
1019 | fputs(j->type == DNS_CACHE_NODATA ? "NODATA" : "NXDOMAIN", f); | |
1020 | fputc('\n', f); | |
1021 | } | |
1022 | } | |
1023 | } | |
1024 | } | |
1025 | ||
1026 | bool dns_cache_is_empty(DnsCache *cache) { | |
1027 | if (!cache) | |
1028 | return true; | |
1029 | ||
1030 | return hashmap_isempty(cache->by_key); | |
1031 | } | |
a150ff5e LP |
1032 | |
1033 | unsigned dns_cache_size(DnsCache *cache) { | |
1034 | if (!cache) | |
1035 | return 0; | |
1036 | ||
1037 | return hashmap_size(cache->by_key); | |
1038 | } |