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>
38 #include "wide-area.h"
40 #define MAX_CACHE_ENTRIES 500
42 typedef struct AvahiWideAreaCacheEntry AvahiWideAreaCacheEntry;
44 struct AvahiWideAreaCacheEntry {
45 AvahiWideAreaLookupEngine *engine;
48 struct timeval timestamp;
49 struct timeval expiry;
51 AvahiTimeEvent *time_event;
53 AVAHI_LLIST_FIELDS(AvahiWideAreaCacheEntry, by_key);
54 AVAHI_LLIST_FIELDS(AvahiWideAreaCacheEntry, cache);
57 struct AvahiWideAreaLookup {
58 AvahiWideAreaLookupEngine *engine;
61 uint32_t id; /* effectively just an uint16_t, but we need it as an index for a hash table */
62 AvahiTimeEvent *time_event;
64 AvahiKey *key, *cname_key;
67 AvahiDnsPacket *packet;
69 AvahiWideAreaLookupCallback callback;
72 AvahiAddress dns_server_used;
74 AVAHI_LLIST_FIELDS(AvahiWideAreaLookup, lookups);
75 AVAHI_LLIST_FIELDS(AvahiWideAreaLookup, by_key);
78 struct AvahiWideAreaLookupEngine {
82 AvahiWatch *watch_ipv4, *watch_ipv6;
87 AVAHI_LLIST_HEAD(AvahiWideAreaCacheEntry, cache);
88 AvahiHashmap *cache_by_key;
89 unsigned cache_n_entries;
92 AVAHI_LLIST_HEAD(AvahiWideAreaLookup, lookups);
93 AvahiHashmap *lookups_by_id;
94 AvahiHashmap *lookups_by_key;
98 AvahiAddress dns_servers[AVAHI_MAX_WIDE_AREA_SERVERS];
99 unsigned n_dns_servers;
100 unsigned current_dns_server;
103 static AvahiWideAreaLookup* find_lookup(AvahiWideAreaLookupEngine *e, uint16_t id) {
104 AvahiWideAreaLookup *l;
109 if (!(l = avahi_hashmap_lookup(e->lookups_by_id, &i)))
120 static int send_to_dns_server(AvahiWideAreaLookupEngine *e, AvahiDnsPacket *p) {
126 if (e->n_dns_servers <= 0)
129 assert(e->current_dns_server < e->n_dns_servers);
131 a = &e->dns_servers[e->current_dns_server];
133 if (a->proto == AVAHI_PROTO_INET) {
138 return avahi_send_dns_packet_ipv4(e->fd_ipv4, AVAHI_IF_UNSPEC, p, &a->data.ipv4, AVAHI_DNS_PORT);
141 assert(a->proto == AVAHI_PROTO_INET6);
146 return avahi_send_dns_packet_ipv6(e->fd_ipv6, AVAHI_IF_UNSPEC, p, &a->data.ipv6, AVAHI_DNS_PORT);
150 static void next_dns_server(AvahiWideAreaLookupEngine *e) {
153 e->current_dns_server++;
155 if (e->current_dns_server >= e->n_dns_servers)
156 e->current_dns_server = 0;
159 static void sender_timeout_callback(AvahiTimeEvent *e, void *userdata) {
160 AvahiWideAreaLookup *l = userdata;
165 /* Try another DNS server after three retries */
166 if (l->n_send >= 3 && avahi_address_cmp(&l->engine->dns_servers[l->engine->current_dns_server], &l->dns_server_used) == 0) {
167 next_dns_server(l->engine);
169 if (avahi_address_cmp(&l->engine->dns_servers[l->engine->current_dns_server], &l->dns_server_used) == 0)
170 /* There is no other DNS server, fail */
174 if (l->n_send >= 6) {
175 avahi_log_warn(__FILE__": Query timed out.");
176 l->callback(l->engine, AVAHI_BROWSER_FAILURE, AVAHI_LOOKUP_CALLBACK_WIDE_AREA, NULL, l->userdata);
177 avahi_wide_area_lookup_free(l);
182 send_to_dns_server(l->engine, l->packet);
185 avahi_time_event_update(e, avahi_elapse_time(&tv, 1000, 0));
188 AvahiWideAreaLookup *avahi_wide_area_lookup_new(
189 AvahiWideAreaLookupEngine *e,
191 AvahiWideAreaLookupCallback callback,
195 AvahiWideAreaLookup *l, *t;
203 l = avahi_new(AvahiWideAreaLookup, 1);
206 l->key = avahi_key_ref(key);
207 l->cname_key = avahi_key_new_cname(l->key);
208 l->callback = callback;
209 l->userdata = userdata;
211 /* If more than 65K wide area quries are issued simultaneously,
212 * this will break. This should be limited by some higher level */
214 for (;; e->next_id++)
215 if (!find_lookup(e, e->next_id))
216 break; /* This ID is not yet used. */
218 l->id = e->next_id++;
220 /* We keep the packet around in case we need to repeat our query */
221 l->packet = avahi_dns_packet_new(0);
223 avahi_dns_packet_set_field(l->packet, AVAHI_DNS_FIELD_ID, (uint16_t) l->id);
224 avahi_dns_packet_set_field(l->packet, AVAHI_DNS_FIELD_FLAGS, AVAHI_DNS_FLAGS(0, 0, 0, 0, 1, 0, 0, 0, 0, 0));
226 p = avahi_dns_packet_append_key(l->packet, key, 0);
229 avahi_dns_packet_set_field(l->packet, AVAHI_DNS_FIELD_QDCOUNT, 1);
231 if (send_to_dns_server(e, l->packet) < 0) {
232 avahi_log_error(__FILE__": Failed to send packet.");
233 avahi_dns_packet_free(l->packet);
234 avahi_key_unref(l->key);
236 avahi_key_unref(l->cname_key);
243 l->time_event = avahi_time_event_new(e->server->time_event_queue, avahi_elapse_time(&tv, 500, 0), sender_timeout_callback, l);
245 avahi_hashmap_insert(e->lookups_by_id, &l->id, l);
247 t = avahi_hashmap_lookup(e->lookups_by_key, l->key);
248 AVAHI_LLIST_PREPEND(AvahiWideAreaLookup, by_key, t, l);
249 avahi_hashmap_replace(e->lookups_by_key, avahi_key_ref(l->key), t);
251 AVAHI_LLIST_PREPEND(AvahiWideAreaLookup, lookups, e->lookups, l);
256 static void lookup_stop(AvahiWideAreaLookup *l) {
262 avahi_time_event_free(l->time_event);
263 l->time_event = NULL;
267 static void lookup_destroy(AvahiWideAreaLookup *l) {
268 AvahiWideAreaLookup *t;
273 t = avahi_hashmap_lookup(l->engine->lookups_by_key, l->key);
274 AVAHI_LLIST_REMOVE(AvahiWideAreaLookup, by_key, t, l);
276 avahi_hashmap_replace(l->engine->lookups_by_key, avahi_key_ref(l->key), t);
278 avahi_hashmap_remove(l->engine->lookups_by_key, l->key);
280 AVAHI_LLIST_REMOVE(AvahiWideAreaLookup, lookups, l->engine->lookups, l);
282 avahi_hashmap_remove(l->engine->lookups_by_id, &l->id);
283 avahi_dns_packet_free(l->packet);
286 avahi_key_unref(l->key);
289 avahi_key_unref(l->cname_key);
294 void avahi_wide_area_lookup_free(AvahiWideAreaLookup *l) {
301 l->engine->cleanup_dead = 1;
305 void avahi_wide_area_cleanup(AvahiWideAreaLookupEngine *e) {
306 AvahiWideAreaLookup *l, *n;
309 while (e->cleanup_dead) {
312 for (l = e->lookups; l; l = n) {
321 static void cache_entry_free(AvahiWideAreaCacheEntry *c) {
322 AvahiWideAreaCacheEntry *t;
326 avahi_time_event_free(c->time_event);
328 AVAHI_LLIST_REMOVE(AvahiWideAreaCacheEntry, cache, c->engine->cache, c);
330 t = avahi_hashmap_lookup(c->engine->cache_by_key, c->record->key);
331 AVAHI_LLIST_REMOVE(AvahiWideAreaCacheEntry, by_key, t, c);
333 avahi_hashmap_replace(c->engine->cache_by_key, avahi_key_ref(c->record->key), t);
335 avahi_hashmap_remove(c->engine->cache_by_key, c->record->key);
337 c->engine->cache_n_entries --;
339 avahi_record_unref(c->record);
343 static void expiry_event(AvahiTimeEvent *te, void *userdata) {
344 AvahiWideAreaCacheEntry *e = userdata;
352 static AvahiWideAreaCacheEntry* find_record_in_cache(AvahiWideAreaLookupEngine *e, AvahiRecord *r) {
353 AvahiWideAreaCacheEntry *c;
358 for (c = avahi_hashmap_lookup(e->cache_by_key, r->key); c; c = c->by_key_next)
359 if (avahi_record_equal_no_ttl(r, c->record))
365 static void run_callbacks(AvahiWideAreaLookupEngine *e, AvahiRecord *r) {
366 AvahiWideAreaLookup *l;
371 for (l = avahi_hashmap_lookup(e->lookups_by_key, r->key); l; l = l->by_key_next) {
372 if (l->dead || !l->callback)
375 l->callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_CALLBACK_WIDE_AREA, r, l->userdata);
378 if (r->key->clazz == AVAHI_DNS_CLASS_IN && r->key->type == AVAHI_DNS_TYPE_CNAME) {
379 /* It's a CNAME record, so we have to scan the all lookups to see if one matches */
381 for (l = e->lookups; l; l = l->lookups_next) {
384 if (l->dead || !l->callback)
387 if ((key = avahi_key_new_cname(l->key))) {
388 if (avahi_key_equal(r->key, key))
389 l->callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_CALLBACK_WIDE_AREA, r, l->userdata);
391 avahi_key_unref(key);
397 static void add_to_cache(AvahiWideAreaLookupEngine *e, AvahiRecord *r) {
398 AvahiWideAreaCacheEntry *c;
404 if ((c = find_record_in_cache(e, r))) {
407 /* Update the existing entry */
408 avahi_record_unref(c->record);
410 AvahiWideAreaCacheEntry *t;
414 /* Enforce cache size */
415 if (e->cache_n_entries >= MAX_CACHE_ENTRIES)
416 /* Eventually we should improve the caching algorithm here */
419 c = avahi_new(AvahiWideAreaCacheEntry, 1);
421 c->time_event = NULL;
423 AVAHI_LLIST_PREPEND(AvahiWideAreaCacheEntry, cache, e->cache, c);
425 /* Add the new entry to the cache entry hash table */
426 t = avahi_hashmap_lookup(e->cache_by_key, r->key);
427 AVAHI_LLIST_PREPEND(AvahiWideAreaCacheEntry, by_key, t, c);
428 avahi_hashmap_replace(e->cache_by_key, avahi_key_ref(r->key), t);
430 e->cache_n_entries ++;
433 c->record = avahi_record_ref(r);
435 gettimeofday(&c->timestamp, NULL);
436 c->expiry = c->timestamp;
437 avahi_timeval_add(&c->expiry, r->ttl * 1000000);
440 avahi_time_event_update(c->time_event, &c->expiry);
442 c->time_event = avahi_time_event_new(e->server->time_event_queue, &c->expiry, expiry_event, c);
450 static void handle_packet(AvahiWideAreaLookupEngine *e, AvahiDnsPacket *p, AvahiAddress *a) {
451 AvahiWideAreaLookup *l = NULL;
457 if (avahi_dns_packet_check_valid(p) < 0 || avahi_dns_packet_is_query(p)) {
458 avahi_log_warn(__FILE__": Ignoring invalid response for wide area datagram.");
462 /* avahi_log_debug(__FILE__": Recieving unicast packet %u", avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID)); */
464 if (!(l = find_lookup(e, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ID)))) {
465 /* avahi_log_warn(__FILE__": Got response for query we didn't send."); */
470 if ((r = avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) & 15) != 0) {
471 /* avahi_log_debug(__FILE__": Response failed for wide area datagram: %i", r); */
473 /* Tell the user about the failure */
475 l->callback(e, r == 3 ? AVAHI_BROWSER_NOT_FOUND : AVAHI_BROWSER_FAILURE, AVAHI_LOOKUP_CALLBACK_WIDE_AREA, NULL, l->userdata);
479 /* Skip over the question */
480 for (i = (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_QDCOUNT); i > 0; i--) {
483 if (!(k = avahi_dns_packet_consume_key(p, NULL))) {
484 avahi_log_warn(__FILE__": Wide area response packet too short.");
491 for (i = (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ANCOUNT) +
492 (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_NSCOUNT) +
493 (int) avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_ARCOUNT); i > 0; i--) {
497 if (!(rr = avahi_dns_packet_consume_record(p, NULL))) {
498 avahi_log_warn(__FILE__": Wide area response packet too short (2).");
504 avahi_record_unref(rr);
507 /** Inform the user that this is the last reply */
508 if (l->callback && !l->dead)
509 l->callback(e, AVAHI_BROWSER_ALL_FOR_NOW, AVAHI_LOOKUP_CALLBACK_WIDE_AREA, NULL, l->userdata);
516 static void socket_event(AvahiWatch *w, int fd, AvahiWatchEvent events, void *userdata) {
517 AvahiWideAreaLookupEngine *e = userdata;
519 AvahiDnsPacket *p = NULL;
521 if (fd == e->fd_ipv4) {
522 struct sockaddr_in sa;
524 if ((p = avahi_recv_dns_packet_ipv4(e->fd_ipv4, &sa, NULL, NULL, NULL)))
525 avahi_address_from_sockaddr((struct sockaddr*) &sa, &a);
527 } else if (fd == e->fd_ipv6) {
528 struct sockaddr_in6 sa6;
530 if ((p = avahi_recv_dns_packet_ipv6(e->fd_ipv6, &sa6, NULL, NULL, NULL)))
531 avahi_address_from_sockaddr((struct sockaddr*) &sa6, &a);
536 handle_packet(e, p, &a);
537 avahi_dns_packet_free(p);
541 AvahiWideAreaLookupEngine *avahi_wide_area_engine_new(AvahiServer *s) {
542 AvahiWideAreaLookupEngine *e;
546 e = avahi_new(AvahiWideAreaLookupEngine, 1);
551 e->fd_ipv4 = avahi_open_unicast_socket_ipv4();
552 e->fd_ipv6 = avahi_open_unicast_socket_ipv6();
554 if (e->fd_ipv4 < 0 && e->fd_ipv6 < 0) {
555 avahi_log_error(__FILE__": Failed to create wide area sockets: %s\n", strerror(errno));
569 e->watch_ipv4 = s->poll_api->watch_new(e->server->poll_api, e->fd_ipv4, AVAHI_WATCH_IN, socket_event, e);
571 e->watch_ipv6 = s->poll_api->watch_new(e->server->poll_api, e->fd_ipv6, AVAHI_WATCH_IN, socket_event, e);
573 e->n_dns_servers = e->current_dns_server = 0;
574 e->next_id = (uint16_t) rand();
576 /* Initialize cache */
577 AVAHI_LLIST_HEAD_INIT(AvahiWideAreaCacheEntry, e->cache);
578 e->cache_by_key = avahi_hashmap_new((AvahiHashFunc) avahi_key_hash, (AvahiEqualFunc) avahi_key_equal, (AvahiFreeFunc) avahi_key_unref, NULL);
579 e->cache_n_entries = 0;
581 /* Initialize lookup list */
582 e->lookups_by_id = avahi_hashmap_new((AvahiHashFunc) avahi_int_hash, (AvahiEqualFunc) avahi_int_equal, NULL, NULL);
583 e->lookups_by_key = avahi_hashmap_new((AvahiHashFunc) avahi_key_hash, (AvahiEqualFunc) avahi_key_equal, (AvahiFreeFunc) avahi_key_unref, NULL);
584 AVAHI_LLIST_HEAD_INIT(AvahiWideAreaLookup, e->lookups);
589 void avahi_wide_area_engine_free(AvahiWideAreaLookupEngine *e) {
592 avahi_wide_area_clear_cache(e);
595 lookup_destroy(e->lookups);
597 avahi_hashmap_free(e->cache_by_key);
598 avahi_hashmap_free(e->lookups_by_id);
599 avahi_hashmap_free(e->lookups_by_key);
602 e->server->poll_api->watch_free(e->watch_ipv4);
605 e->server->poll_api->watch_free(e->watch_ipv6);
616 void avahi_wide_area_clear_cache(AvahiWideAreaLookupEngine *e) {
620 cache_entry_free(e->cache);
622 assert(e->cache_n_entries == 0);
626 void avahi_wide_area_set_servers(AvahiWideAreaLookupEngine *e, const AvahiAddress *a, unsigned n) {
631 for (e->n_dns_servers = 0; n > 0 && e->n_dns_servers < AVAHI_MAX_WIDE_AREA_SERVERS; a++, n--)
632 if ((a->proto == AVAHI_PROTO_INET && e->fd_ipv4 >= 0) || (a->proto == AVAHI_PROTO_INET6 && e->fd_ipv6 >= 0))
633 e->dns_servers[e->n_dns_servers++] = *a;
636 e->n_dns_servers = 0;
639 e->current_dns_server = 0;
641 avahi_wide_area_clear_cache(e);
644 void avahi_wide_area_cache_dump(AvahiWideAreaLookupEngine *e, AvahiDumpCallback callback, void* userdata) {
645 AvahiWideAreaCacheEntry *c;
650 callback(";; WIDE AREA CACHE ;;; ", userdata);
652 for (c = e->cache; c; c = c->cache_next) {
653 char *t = avahi_record_to_string(c->record);
654 callback(t, userdata);
659 unsigned avahi_wide_area_scan_cache(AvahiWideAreaLookupEngine *e, AvahiKey *key, AvahiWideAreaLookupCallback callback, void *userdata) {
660 AvahiWideAreaCacheEntry *c;
668 for (c = avahi_hashmap_lookup(e->cache_by_key, key); c; c = c->by_key_next) {
669 callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_CALLBACK_WIDE_AREA|AVAHI_LOOKUP_CALLBACK_CACHED, c->record, userdata);
673 if ((cname_key = avahi_key_new_cname(key))) {
675 for (c = avahi_hashmap_lookup(e->cache_by_key, cname_key); c; c = c->by_key_next) {
676 callback(e, AVAHI_BROWSER_NEW, AVAHI_LOOKUP_CALLBACK_WIDE_AREA|AVAHI_LOOKUP_CALLBACK_CACHED, c->record, userdata);
680 avahi_key_unref(cname_key);
686 int avahi_wide_area_has_servers(AvahiWideAreaLookupEngine *e) {
689 return e->n_dns_servers > 0;