4 This file is part of avahi.
6 avahi is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
11 avahi is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
14 Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with avahi; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
31 #include <avahi-common/malloc.h>
32 #include <avahi-common/error.h>
33 #include <avahi-common/timeval.h>
40 #include "wide-area.h"
42 #define MAX_CACHE_ENTRIES 500
44 typedef struct AvahiWideAreaCacheEntry AvahiWideAreaCacheEntry;
46 struct AvahiWideAreaCacheEntry {
47 AvahiWideAreaLookupEngine *engine;
50 struct timeval timestamp;
51 struct timeval expiry;
53 AvahiTimeEvent *time_event;
55 AVAHI_LLIST_FIELDS(AvahiWideAreaCacheEntry, by_key);
56 AVAHI_LLIST_FIELDS(AvahiWideAreaCacheEntry, cache);
59 struct AvahiWideAreaLookup {
60 AvahiWideAreaLookupEngine *engine;
63 uint32_t id; /* effectively just an uint16_t, but we need it as an index for a hash table */
64 AvahiTimeEvent *time_event;
66 AvahiKey *key, *cname_key;
69 AvahiDnsPacket *packet;
71 AvahiWideAreaLookupCallback callback;
74 AvahiAddress dns_server_used;
76 AVAHI_LLIST_FIELDS(AvahiWideAreaLookup, lookups);
77 AVAHI_LLIST_FIELDS(AvahiWideAreaLookup, by_key);
80 struct AvahiWideAreaLookupEngine {
84 AvahiWatch *watch_ipv4, *watch_ipv6;
89 AVAHI_LLIST_HEAD(AvahiWideAreaCacheEntry, cache);
90 AvahiHashmap *cache_by_key;
91 unsigned cache_n_entries;
94 AVAHI_LLIST_HEAD(AvahiWideAreaLookup, lookups);
95 AvahiHashmap *lookups_by_id;
96 AvahiHashmap *lookups_by_key;
100 AvahiAddress dns_servers[AVAHI_MAX_WIDE_AREA_SERVERS];
101 unsigned n_dns_servers;
102 unsigned current_dns_server;
105 static AvahiWideAreaLookup* find_lookup(AvahiWideAreaLookupEngine *e, uint16_t id) {
106 AvahiWideAreaLookup *l;
111 if (!(l = avahi_hashmap_lookup(e->lookups_by_id, &i)))
122 static int send_to_dns_server(AvahiWideAreaLookupEngine *e, AvahiDnsPacket *p) {
128 if (e->n_dns_servers <= 0)
131 assert(e->current_dns_server < e->n_dns_servers);
133 a = &e->dns_servers[e->current_dns_server];
135 if (a->proto == AVAHI_PROTO_INET) {
140 return avahi_send_dns_packet_ipv4(e->fd_ipv4, AVAHI_IF_UNSPEC, p, &a->data.ipv4, AVAHI_DNS_PORT);
143 assert(a->proto == AVAHI_PROTO_INET6);
148 return avahi_send_dns_packet_ipv6(e->fd_ipv6, AVAHI_IF_UNSPEC, p, &a->data.ipv6, AVAHI_DNS_PORT);
152 static void next_dns_server(AvahiWideAreaLookupEngine *e) {
155 e->current_dns_server++;
157 if (e->current_dns_server >= e->n_dns_servers)
158 e->current_dns_server = 0;
161 static void sender_timeout_callback(AvahiTimeEvent *e, void *userdata) {
162 AvahiWideAreaLookup *l = userdata;
167 /* Try another DNS server after three retries */
168 if (l->n_send >= 3 && avahi_address_cmp(&l->engine->dns_servers[l->engine->current_dns_server], &l->dns_server_used) == 0) {
169 next_dns_server(l->engine);
171 if (avahi_address_cmp(&l->engine->dns_servers[l->engine->current_dns_server], &l->dns_server_used) == 0)
172 /* There is no other DNS server, fail */
176 if (l->n_send >= 6) {
177 avahi_log_warn(__FILE__": Query timed out.");
178 avahi_server_set_errno(l->engine->server, AVAHI_ERR_TIMEOUT);
179 l->callback(l->engine, AVAHI_BROWSER_FAILURE, AVAHI_LOOKUP_RESULT_WIDE_AREA, NULL, l->userdata);
180 avahi_wide_area_lookup_free(l);
185 send_to_dns_server(l->engine, l->packet);
188 avahi_time_event_update(e, avahi_elapse_time(&tv, 1000, 0));
191 AvahiWideAreaLookup *avahi_wide_area_lookup_new(
192 AvahiWideAreaLookupEngine *e,
194 AvahiWideAreaLookupCallback callback,
198 AvahiWideAreaLookup *l, *t;
206 l = avahi_new(AvahiWideAreaLookup, 1);
209 l->key = avahi_key_ref(key);
210 l->cname_key = avahi_key_new_cname(l->key);
211 l->callback = callback;
212 l->userdata = userdata;
214 /* If more than 65K wide area quries are issued simultaneously,
215 * this will break. This should be limited by some higher level */
217 for (;; e->next_id++)
218 if (!find_lookup(e, e->next_id))
219 break; /* This ID is not yet used. */
221 l->id = e->next_id++;
223 /* We keep the packet around in case we need to repeat our query */
224 l->packet = avahi_dns_packet_new(0);
226 avahi_dns_packet_set_field(l->packet, AVAHI_DNS_FIELD_ID, (uint16_t) l->id);
227 avahi_dns_packet_set_field(l->packet, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 1, 0, 0, 0, 0, 0));
229 p = avahi_dns_packet_append_key(l->packet, key, 0);
232 avahi_dns_packet_set_field(l->packet, AVAHI_DNS_FIELD_QDCOUNT, 1);
234 if (send_to_dns_server(e, l->packet) < 0) {
235 avahi_log_error(__FILE__": Failed to send packet.");
236 avahi_dns_packet_free(l->packet);
237 avahi_key_unref(l->key);
239 avahi_key_unref(l->cname_key);
246 l->time_event = avahi_time_event_new(e->server->time_event_queue, avahi_elapse_time(&tv, 500, 0), sender_timeout_callback, l);
248 avahi_hashmap_insert(e->lookups_by_id, &l->id, l);
250 t = avahi_hashmap_lookup(e->lookups_by_key, l->key);
251 AVAHI_LLIST_PREPEND(AvahiWideAreaLookup, by_key, t, l);
252 avahi_hashmap_replace(e->lookups_by_key, avahi_key_ref(l->key), t);
254 AVAHI_LLIST_PREPEND(AvahiWideAreaLookup, lookups, e->lookups, l);
259 static void lookup_stop(AvahiWideAreaLookup *l) {
265 avahi_time_event_free(l->time_event);
266 l->time_event = NULL;
270 static void lookup_destroy(AvahiWideAreaLookup *l) {
271 AvahiWideAreaLookup *t;
276 t = avahi_hashmap_lookup(l->engine->lookups_by_key, l->key);
277 AVAHI_LLIST_REMOVE(AvahiWideAreaLookup, by_key, t, l);
279 avahi_hashmap_replace(l->engine->lookups_by_key, avahi_key_ref(l->key), t);
281 avahi_hashmap_remove(l->engine->lookups_by_key, l->key);
283 AVAHI_LLIST_REMOVE(AvahiWideAreaLookup, lookups, l->engine->lookups, l);
285 avahi_hashmap_remove(l->engine->lookups_by_id, &l->id);
286 avahi_dns_packet_free(l->packet);
289 avahi_key_unref(l->key);
292 avahi_key_unref(l->cname_key);
297 void avahi_wide_area_lookup_free(AvahiWideAreaLookup *l) {
304 l->engine->cleanup_dead = 1;
308 void avahi_wide_area_cleanup(AvahiWideAreaLookupEngine *e) {
309 AvahiWideAreaLookup *l, *n;
312 while (e->cleanup_dead) {
315 for (l = e->lookups; l; l = n) {
324 static void cache_entry_free(AvahiWideAreaCacheEntry *c) {
325 AvahiWideAreaCacheEntry *t;
329 avahi_time_event_free(c->time_event);
331 AVAHI_LLIST_REMOVE(AvahiWideAreaCacheEntry, cache, c->engine->cache, c);
333 t = avahi_hashmap_lookup(c->engine->cache_by_key, c->record->key);
334 AVAHI_LLIST_REMOVE(AvahiWideAreaCacheEntry, by_key, t, c);
336 avahi_hashmap_replace(c->engine->cache_by_key, avahi_key_ref(c->record->key), t);
338 avahi_hashmap_remove(c->engine->cache_by_key, c->record->key);
340 c->engine->cache_n_entries --;
342 avahi_record_unref(c->record);
346 static void expiry_event(AvahiTimeEvent *te, void *userdata) {
347 AvahiWideAreaCacheEntry *e = userdata;
355 static AvahiWideAreaCacheEntry* find_record_in_cache(AvahiWideAreaLookupEngine *e, AvahiRecord *r) {
356 AvahiWideAreaCacheEntry *c;
361 for (c = avahi_hashmap_lookup(e->cache_by_key, r->key); c; c = c->by_key_next)
362 if (avahi_record_equal_no_ttl(r, c->record))
368 static void run_callbacks(AvahiWideAreaLookupEngine *e, AvahiRecord *r) {
369 AvahiWideAreaLookup *l;
374 for (l = avahi_hashmap_lookup(e->lookups_by_key, r->key); l; l = l->by_key_next) {
375 if (l->dead || !l->callback)
378 l->callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_RESULT_WIDE_AREA, r, l->userdata);
381 if (r->key->clazz == AVAHI_DNS_CLASS_IN && r->key->type == AVAHI_DNS_TYPE_CNAME) {
382 /* It's a CNAME record, so we have to scan the all lookups to see if one matches */
384 for (l = e->lookups; l; l = l->lookups_next) {
387 if (l->dead || !l->callback)
390 if ((key = avahi_key_new_cname(l->key))) {
391 if (avahi_key_equal(r->key, key))
392 l->callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_RESULT_WIDE_AREA, r, l->userdata);
394 avahi_key_unref(key);
400 static void add_to_cache(AvahiWideAreaLookupEngine *e, AvahiRecord *r) {
401 AvahiWideAreaCacheEntry *c;
407 if ((c = find_record_in_cache(e, r))) {
410 /* Update the existing entry */
411 avahi_record_unref(c->record);
413 AvahiWideAreaCacheEntry *t;
417 /* Enforce cache size */
418 if (e->cache_n_entries >= MAX_CACHE_ENTRIES)
419 /* Eventually we should improve the caching algorithm here */
422 c = avahi_new(AvahiWideAreaCacheEntry, 1);
424 c->time_event = NULL;
426 AVAHI_LLIST_PREPEND(AvahiWideAreaCacheEntry, cache, e->cache, c);
428 /* Add the new entry to the cache entry hash table */
429 t = avahi_hashmap_lookup(e->cache_by_key, r->key);
430 AVAHI_LLIST_PREPEND(AvahiWideAreaCacheEntry, by_key, t, c);
431 avahi_hashmap_replace(e->cache_by_key, avahi_key_ref(r->key), t);
433 e->cache_n_entries ++;
436 c->record = avahi_record_ref(r);
438 gettimeofday(&c->timestamp, NULL);
439 c->expiry = c->timestamp;
440 avahi_timeval_add(&c->expiry, r->ttl * 1000000);
443 avahi_time_event_update(c->time_event, &c->expiry);
445 c->time_event = avahi_time_event_new(e->server->time_event_queue, &c->expiry, expiry_event, c);
453 static int map_dns_error(uint16_t error) {
454 static const int table[16] = {
456 AVAHI_ERR_DNS_FORMERR,
457 AVAHI_ERR_DNS_SERVFAIL,
458 AVAHI_ERR_DNS_NXDOMAIN,
459 AVAHI_ERR_DNS_NOTIMP,
460 AVAHI_ERR_DNS_REFUSED,
461 AVAHI_ERR_DNS_YXDOMAIN,
462 AVAHI_ERR_DNS_YXRRSET,
463 AVAHI_ERR_DNS_NXRRSET,
464 AVAHI_ERR_DNS_NOTAUTH,
465 AVAHI_ERR_DNS_NOTZONE,
466 AVAHI_ERR_INVALID_DNS_ERROR,
467 AVAHI_ERR_INVALID_DNS_ERROR,
468 AVAHI_ERR_INVALID_DNS_ERROR,
469 AVAHI_ERR_INVALID_DNS_ERROR,
470 AVAHI_ERR_INVALID_DNS_ERROR
478 static void handle_packet(AvahiWideAreaLookupEngine *e, AvahiDnsPacket *p, AvahiAddress *a) {
479 AvahiWideAreaLookup *l = NULL;
482 AvahiBrowserEvent final_event = AVAHI_BROWSER_ALL_FOR_NOW;
487 /* Some superficial validity tests */
488 if (avahi_dns_packet_check_valid(p) < 0 || avahi_dns_packet_is_query(p)) {
489 avahi_log_warn(__FILE__": Ignoring invalid response for wide area datagram.");
493 /* Look for the lookup that issued this query */
494 if (!(l = find_lookup(e, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID))) || l->dead)
497 /* Check whether this a packet indicating a failure */
498 if ((r = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & 15) != 0 ||
499 avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ANCOUNT) == 0) {
501 avahi_server_set_errno(e->server, r == 0 ? AVAHI_ERR_NOT_FOUND : map_dns_error(r));
502 /* Tell the user about the failure */
503 final_event = AVAHI_BROWSER_FAILURE;
505 /* We go on here, since some of the records contained in the
506 reply might be interesting in some way */
509 /* Skip over the question */
510 for (i = (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); i > 0; i--) {
513 if (!(k = avahi_dns_packet_consume_key(p, NULL))) {
514 avahi_log_warn(__FILE__": Wide area response packet too short.");
515 avahi_server_set_errno(e->server, AVAHI_ERR_INVALID_PACKET);
516 final_event = AVAHI_BROWSER_FAILURE;
523 /* Process responses */
524 for (i = (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ANCOUNT) +
525 (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_NSCOUNT) +
526 (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ARCOUNT); i > 0; i--) {
530 if (!(rr = avahi_dns_packet_consume_record(p, NULL))) {
531 avahi_log_warn(__FILE__": Wide area response packet too short (2).");
532 avahi_server_set_errno(e->server, AVAHI_ERR_INVALID_PACKET);
533 final_event = AVAHI_BROWSER_FAILURE;
538 avahi_record_unref(rr);
545 l->callback(e, final_event, AVAHI_LOOKUP_RESULT_WIDE_AREA, NULL, l->userdata);
551 static void socket_event(AvahiWatch *w, int fd, AvahiWatchEvent events, void *userdata) {
552 AvahiWideAreaLookupEngine *e = userdata;
554 AvahiDnsPacket *p = NULL;
556 if (fd == e->fd_ipv4) {
557 struct sockaddr_in sa;
559 if ((p = avahi_recv_dns_packet_ipv4(e->fd_ipv4, &sa, NULL, NULL, NULL)))
560 avahi_address_from_sockaddr((struct sockaddr*) &sa, &a);
562 } else if (fd == e->fd_ipv6) {
563 struct sockaddr_in6 sa6;
565 if ((p = avahi_recv_dns_packet_ipv6(e->fd_ipv6, &sa6, NULL, NULL, NULL)))
566 avahi_address_from_sockaddr((struct sockaddr*) &sa6, &a);
571 handle_packet(e, p, &a);
572 avahi_dns_packet_free(p);
576 AvahiWideAreaLookupEngine *avahi_wide_area_engine_new(AvahiServer *s) {
577 AvahiWideAreaLookupEngine *e;
581 e = avahi_new(AvahiWideAreaLookupEngine, 1);
586 e->fd_ipv4 = avahi_open_unicast_socket_ipv4();
587 e->fd_ipv6 = avahi_open_unicast_socket_ipv6();
589 if (e->fd_ipv4 < 0 && e->fd_ipv6 < 0) {
590 avahi_log_error(__FILE__": Failed to create wide area sockets: %s", strerror(errno));
604 e->watch_ipv4 = s->poll_api->watch_new(e->server->poll_api, e->fd_ipv4, AVAHI_WATCH_IN, socket_event, e);
606 e->watch_ipv6 = s->poll_api->watch_new(e->server->poll_api, e->fd_ipv6, AVAHI_WATCH_IN, socket_event, e);
608 e->n_dns_servers = e->current_dns_server = 0;
609 e->next_id = (uint16_t) rand();
611 /* Initialize cache */
612 AVAHI_LLIST_HEAD_INIT(AvahiWideAreaCacheEntry, e->cache);
613 e->cache_by_key = avahi_hashmap_new((AvahiHashFunc) avahi_key_hash, (AvahiEqualFunc) avahi_key_equal, (AvahiFreeFunc) avahi_key_unref, NULL);
614 e->cache_n_entries = 0;
616 /* Initialize lookup list */
617 e->lookups_by_id = avahi_hashmap_new((AvahiHashFunc) avahi_int_hash, (AvahiEqualFunc) avahi_int_equal, NULL, NULL);
618 e->lookups_by_key = avahi_hashmap_new((AvahiHashFunc) avahi_key_hash, (AvahiEqualFunc) avahi_key_equal, (AvahiFreeFunc) avahi_key_unref, NULL);
619 AVAHI_LLIST_HEAD_INIT(AvahiWideAreaLookup, e->lookups);
624 void avahi_wide_area_engine_free(AvahiWideAreaLookupEngine *e) {
627 avahi_wide_area_clear_cache(e);
630 lookup_destroy(e->lookups);
632 avahi_hashmap_free(e->cache_by_key);
633 avahi_hashmap_free(e->lookups_by_id);
634 avahi_hashmap_free(e->lookups_by_key);
637 e->server->poll_api->watch_free(e->watch_ipv4);
640 e->server->poll_api->watch_free(e->watch_ipv6);
651 void avahi_wide_area_clear_cache(AvahiWideAreaLookupEngine *e) {
655 cache_entry_free(e->cache);
657 assert(e->cache_n_entries == 0);
660 void avahi_wide_area_set_servers(AvahiWideAreaLookupEngine *e, const AvahiAddress *a, unsigned n) {
664 for (e->n_dns_servers = 0; n > 0 && e->n_dns_servers < AVAHI_MAX_WIDE_AREA_SERVERS; a++, n--)
665 if ((a->proto == AVAHI_PROTO_INET && e->fd_ipv4 >= 0) || (a->proto == AVAHI_PROTO_INET6 && e->fd_ipv6 >= 0))
666 e->dns_servers[e->n_dns_servers++] = *a;
669 e->n_dns_servers = 0;
672 e->current_dns_server = 0;
674 avahi_wide_area_clear_cache(e);
677 void avahi_wide_area_cache_dump(AvahiWideAreaLookupEngine *e, AvahiDumpCallback callback, void* userdata) {
678 AvahiWideAreaCacheEntry *c;
683 callback(";; WIDE AREA CACHE ;;; ", userdata);
685 for (c = e->cache; c; c = c->cache_next) {
686 char *t = avahi_record_to_string(c->record);
687 callback(t, userdata);
692 unsigned avahi_wide_area_scan_cache(AvahiWideAreaLookupEngine *e, AvahiKey *key, AvahiWideAreaLookupCallback callback, void *userdata) {
693 AvahiWideAreaCacheEntry *c;
701 for (c = avahi_hashmap_lookup(e->cache_by_key, key); c; c = c->by_key_next) {
702 callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_RESULT_WIDE_AREA|AVAHI_LOOKUP_RESULT_CACHED, c->record, userdata);
706 if ((cname_key = avahi_key_new_cname(key))) {
708 for (c = avahi_hashmap_lookup(e->cache_by_key, cname_key); c; c = c->by_key_next) {
709 callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_RESULT_WIDE_AREA|AVAHI_LOOKUP_RESULT_CACHED, c->record, userdata);
713 avahi_key_unref(cname_key);
719 int avahi_wide_area_has_servers(AvahiWideAreaLookupEngine *e) {
722 return e->n_dns_servers > 0;