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
26 #include <avahi-common/timeval.h>
27 #include <avahi-common/malloc.h>
29 #include "query-sched.h"
32 #define AVAHI_QUERY_HISTORY_MSEC 100
33 #define AVAHI_QUERY_DEFER_MSEC 100
35 typedef struct AvahiQueryJob AvahiQueryJob;
36 typedef struct AvahiKnownAnswer AvahiKnownAnswer;
38 struct AvahiQueryJob {
39 AvahiQueryScheduler *scheduler;
40 AvahiTimeEvent *time_event;
43 struct timeval delivery;
47 AVAHI_LLIST_FIELDS(AvahiQueryJob, jobs);
50 struct AvahiKnownAnswer {
51 AvahiQueryScheduler *scheduler;
54 AVAHI_LLIST_FIELDS(AvahiKnownAnswer, known_answer);
57 struct AvahiQueryScheduler {
58 AvahiInterface *interface;
59 AvahiTimeEventQueue *time_event_queue;
61 AVAHI_LLIST_HEAD(AvahiQueryJob, jobs);
62 AVAHI_LLIST_HEAD(AvahiQueryJob, history);
63 AVAHI_LLIST_HEAD(AvahiKnownAnswer, known_answers);
66 static AvahiQueryJob* job_new(AvahiQueryScheduler *s, AvahiKey *key, int done) {
72 if (!(qj = avahi_new(AvahiQueryJob, 1))) {
73 avahi_log_error(__FILE__": Out of memory");
78 qj->key = avahi_key_ref(key);
79 qj->time_event = NULL;
81 if ((qj->done = done))
82 AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj);
84 AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->jobs, qj);
89 static void job_free(AvahiQueryScheduler *s, AvahiQueryJob *qj) {
94 avahi_time_event_free(qj->time_event);
97 AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->history, qj);
99 AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->jobs, qj);
101 avahi_key_unref(qj->key);
105 static void elapse_callback(AvahiTimeEvent *e, void* data);
107 static void job_set_elapse_time(AvahiQueryScheduler *s, AvahiQueryJob *qj, unsigned msec, unsigned jitter) {
113 avahi_elapse_time(&tv, msec, jitter);
116 avahi_time_event_update(qj->time_event, &tv);
118 qj->time_event = avahi_time_event_new(s->time_event_queue, &tv, elapse_callback, qj);
121 static void job_mark_done(AvahiQueryScheduler *s, AvahiQueryJob *qj) {
127 AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->jobs, qj);
128 AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj);
132 job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0);
133 gettimeofday(&qj->delivery, NULL);
136 AvahiQueryScheduler *avahi_query_scheduler_new(AvahiInterface *i) {
137 AvahiQueryScheduler *s;
140 if (!(s = avahi_new(AvahiQueryScheduler, 1))) {
141 avahi_log_error(__FILE__": Out of memory");
142 return NULL; /* OOM */
146 s->time_event_queue = i->monitor->server->time_event_queue;
148 AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->jobs);
149 AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->history);
150 AVAHI_LLIST_HEAD_INIT(AvahiKnownAnswer, s->known_answers);
155 void avahi_query_scheduler_free(AvahiQueryScheduler *s) {
158 assert(!s->known_answers);
159 avahi_query_scheduler_clear(s);
163 void avahi_query_scheduler_clear(AvahiQueryScheduler *s) {
167 job_free(s, s->jobs);
169 job_free(s, s->history);
172 static void* known_answer_walk_callback(AvahiCache *c, AvahiKey *pattern, AvahiCacheEntry *e, void* userdata) {
173 AvahiQueryScheduler *s = userdata;
174 AvahiKnownAnswer *ka;
181 if (avahi_cache_entry_half_ttl(c, e))
184 if (!(ka = avahi_new0(AvahiKnownAnswer, 1))) {
185 avahi_log_error(__FILE__": Out of memory");
190 ka->record = avahi_record_ref(e->record);
192 AVAHI_LLIST_PREPEND(AvahiKnownAnswer, known_answer, s->known_answers, ka);
196 static int packet_add_query_job(AvahiQueryScheduler *s, AvahiDnsPacket *p, AvahiQueryJob *qj) {
201 if (!avahi_dns_packet_append_key(p, qj->key, 0))
204 /* Add all matching known answers to the list */
205 avahi_cache_walk(s->interface->cache, qj->key, known_answer_walk_callback, s);
207 job_mark_done(s, qj);
212 static void append_known_answers_and_send(AvahiQueryScheduler *s, AvahiDnsPacket *p) {
213 AvahiKnownAnswer *ka;
220 while ((ka = s->known_answers)) {
223 while (!avahi_dns_packet_append_record(p, ka->record, 0, 0)) {
225 if (avahi_dns_packet_is_empty(p)) {
226 /* The record is too large to fit into one packet, so
227 there's no point in sending it. Better is letting
228 the owner of the record send it as a response. This
229 has the advantage of a cache refresh. */
235 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) | AVAHI_DNS_FLAG_TC);
236 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n);
237 avahi_interface_send_packet(s->interface, p);
238 avahi_dns_packet_free(p);
240 p = avahi_dns_packet_new_query(s->interface->hardware->mtu);
244 AVAHI_LLIST_REMOVE(AvahiKnownAnswer, known_answer, s->known_answers, ka);
245 avahi_record_unref(ka->record);
252 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n);
253 avahi_interface_send_packet(s->interface, p);
254 avahi_dns_packet_free(p);
257 static void elapse_callback(AVAHI_GCC_UNUSED AvahiTimeEvent *e, void* data) {
258 AvahiQueryJob *qj = data;
259 AvahiQueryScheduler *s;
268 /* Lets remove it from the history */
273 assert(!s->known_answers);
275 if (!(p = avahi_dns_packet_new_query(s->interface->hardware->mtu)))
278 b = packet_add_query_job(s, p, qj);
279 assert(b); /* An query must always fit in */
282 /* Try to fill up packet with more queries, if available */
285 if (!packet_add_query_job(s, p, s->jobs))
291 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_QDCOUNT, n);
293 /* Now add known answers */
294 append_known_answers_and_send(s, p);
297 static AvahiQueryJob* find_scheduled_job(AvahiQueryScheduler *s, AvahiKey *key) {
303 for (qj = s->jobs; qj; qj = qj->jobs_next) {
306 if (avahi_key_equal(qj->key, key))
313 static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) {
319 for (qj = s->history; qj; qj = qj->jobs_next) {
322 if (avahi_key_equal(qj->key, key)) {
323 /* Check whether this entry is outdated */
325 if (avahi_age(&qj->delivery) > AVAHI_QUERY_HISTORY_MSEC*1000) {
326 /* it is outdated, so let's remove it */
338 int avahi_query_scheduler_post(AvahiQueryScheduler *s, AvahiKey *key, int immediately) {
345 if ((qj = find_history_job(s, key))) {
346 /* avahi_log_debug("Query suppressed by local duplicate suppression (history)"); */
350 avahi_elapse_time(&tv, immediately ? 0 : AVAHI_QUERY_DEFER_MSEC, 0);
352 if ((qj = find_scheduled_job(s, key))) {
353 /* Duplicate questions suppression */
355 /* avahi_log_debug("Query suppressed by local duplicate suppression (scheduled)"); */
357 if (avahi_timeval_compare(&tv, &qj->delivery) < 0) {
358 /* If the new entry should be scheduled earlier,
359 * update the old entry */
361 avahi_time_event_update(qj->time_event, &qj->delivery);
366 /* avahi_log_debug("Accepted new query job."); */
368 if (!(qj = job_new(s, key, 0)))
372 qj->time_event = avahi_time_event_new(s->time_event_queue, &qj->delivery, elapse_callback, qj);
378 void avahi_query_scheduler_incoming(AvahiQueryScheduler *s, AvahiKey *key) {
384 /* This function is called whenever an incoming query was
385 * receieved. We drop scheduled queries that match. The keyword is
386 * "DUPLICATE QUESTION SUPPRESION". */
388 if ((qj = find_scheduled_job(s, key))) {
389 /* avahi_log_debug("Query suppressed by distributed duplicate suppression"); */
390 job_mark_done(s, qj);
394 if (!(qj = job_new(s, key, 1)))
397 gettimeofday(&qj->delivery, NULL);
398 job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0);