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 "response-sched.h"
32 /* Local packets are supressed this long after sending them */
33 #define AVAHI_RESPONSE_HISTORY_MSEC 500
35 /* Local packets are deferred this long before sending them */
36 #define AVAHI_RESPONSE_DEFER_MSEC 20
38 /* Additional jitter for deferred packets */
39 #define AVAHI_RESPONSE_JITTER_MSEC 100
41 /* Remote packets can suppress local traffic as long as this value */
42 #define AVAHI_RESPONSE_SUPPRESS_MSEC 700
44 typedef struct AvahiResponseJob AvahiResponseJob;
50 } AvahiResponseJobState;
52 struct AvahiResponseJob {
53 AvahiResponseScheduler *scheduler;
54 AvahiTimeEvent *time_event;
56 AvahiResponseJobState state;
57 struct timeval delivery;
64 AVAHI_LLIST_FIELDS(AvahiResponseJob, jobs);
67 struct AvahiResponseScheduler {
68 AvahiInterface *interface;
69 AvahiTimeEventQueue *time_event_queue;
71 AVAHI_LLIST_HEAD(AvahiResponseJob, jobs);
72 AVAHI_LLIST_HEAD(AvahiResponseJob, history);
73 AVAHI_LLIST_HEAD(AvahiResponseJob, suppressed);
76 static AvahiResponseJob* job_new(AvahiResponseScheduler *s, AvahiRecord *record, AvahiResponseJobState state) {
82 if (!(rj = avahi_new(AvahiResponseJob, 1))) {
83 avahi_log_error(__FILE__": Out of memory");
88 rj->record = avahi_record_ref(record);
89 rj->time_event = NULL;
91 rj->querier_valid = 0;
93 if ((rj->state = state) == AVAHI_SCHEDULED)
94 AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->jobs, rj);
95 else if (rj->state == AVAHI_DONE)
96 AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->history, rj);
97 else /* rj->state == AVAHI_SUPPRESSED */
98 AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->suppressed, rj);
103 static void job_free(AvahiResponseScheduler *s, AvahiResponseJob *rj) {
108 avahi_time_event_free(rj->time_event);
110 if (rj->state == AVAHI_SCHEDULED)
111 AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->jobs, rj);
112 else if (rj->state == AVAHI_DONE)
113 AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->history, rj);
114 else /* rj->state == AVAHI_SUPPRESSED */
115 AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->suppressed, rj);
117 avahi_record_unref(rj->record);
121 static void elapse_callback(AvahiTimeEvent *e, void* data);
123 static void job_set_elapse_time(AvahiResponseScheduler *s, AvahiResponseJob *rj, unsigned msec, unsigned jitter) {
129 avahi_elapse_time(&tv, msec, jitter);
132 avahi_time_event_update(rj->time_event, &tv);
134 rj->time_event = avahi_time_event_new(s->time_event_queue, &tv, elapse_callback, rj);
137 static void job_mark_done(AvahiResponseScheduler *s, AvahiResponseJob *rj) {
141 assert(rj->state == AVAHI_SCHEDULED);
143 AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->jobs, rj);
144 AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->history, rj);
146 rj->state = AVAHI_DONE;
148 job_set_elapse_time(s, rj, AVAHI_RESPONSE_HISTORY_MSEC, 0);
150 gettimeofday(&rj->delivery, NULL);
153 AvahiResponseScheduler *avahi_response_scheduler_new(AvahiInterface *i) {
154 AvahiResponseScheduler *s;
157 if (!(s = avahi_new(AvahiResponseScheduler, 1))) {
158 avahi_log_error(__FILE__": Out of memory");
163 s->time_event_queue = i->monitor->server->time_event_queue;
165 AVAHI_LLIST_HEAD_INIT(AvahiResponseJob, s->jobs);
166 AVAHI_LLIST_HEAD_INIT(AvahiResponseJob, s->history);
167 AVAHI_LLIST_HEAD_INIT(AvahiResponseJob, s->suppressed);
172 void avahi_response_scheduler_free(AvahiResponseScheduler *s) {
175 avahi_response_scheduler_clear(s);
179 void avahi_response_scheduler_clear(AvahiResponseScheduler *s) {
183 job_free(s, s->jobs);
185 job_free(s, s->history);
186 while (s->suppressed)
187 job_free(s, s->suppressed);
190 static void enumerate_aux_records_callback(AvahiServer *s, AvahiRecord *r, int flush_cache, void* userdata) {
191 AvahiResponseJob *rj = userdata;
196 avahi_response_scheduler_post(rj->scheduler, r, flush_cache, rj->querier_valid ? &rj->querier : NULL, 0);
199 static int packet_add_response_job(AvahiResponseScheduler *s, AvahiDnsPacket *p, AvahiResponseJob *rj) {
204 /* Try to add this record to the packet */
205 if (!avahi_dns_packet_append_record(p, rj->record, rj->flush_cache, 0))
208 /* Ok, this record will definitely be sent, so schedule the
209 * auxilliary packets, too */
210 avahi_server_enumerate_aux_records(s->interface->monitor->server, s->interface, rj->record, enumerate_aux_records_callback, rj);
211 job_mark_done(s, rj);
216 static void send_response_packet(AvahiResponseScheduler *s, AvahiResponseJob *rj) {
223 if (!(p = avahi_dns_packet_new_response(s->interface->hardware->mtu, 1)))
227 /* Put it in the packet. */
228 if (packet_add_response_job(s, p, rj)) {
230 /* Try to fill up packet with more responses, if available */
233 if (!packet_add_response_job(s, p, s->jobs))
242 avahi_dns_packet_free(p);
244 /* OK, the packet was too small, so create one that fits */
245 size = avahi_record_get_estimate_size(rj->record) + AVAHI_DNS_PACKET_HEADER_SIZE;
247 if (size > AVAHI_DNS_PACKET_SIZE_MAX)
248 size = AVAHI_DNS_PACKET_SIZE_MAX;
250 if (!(p = avahi_dns_packet_new_response(size, 1)))
253 if (!packet_add_response_job(s, p, rj)) {
254 avahi_dns_packet_free(p);
256 avahi_log_warn("Record too large, cannot send");
257 job_mark_done(s, rj);
262 avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n);
263 avahi_interface_send_packet(s->interface, p);
264 avahi_dns_packet_free(p);
267 static void elapse_callback(AvahiTimeEvent *e, void* data) {
268 AvahiResponseJob *rj = data;
272 if (rj->state == AVAHI_DONE || rj->state == AVAHI_SUPPRESSED)
273 job_free(rj->scheduler, rj); /* Lets drop this entry */
275 send_response_packet(rj->scheduler, rj);
278 static AvahiResponseJob* find_scheduled_job(AvahiResponseScheduler *s, AvahiRecord *record) {
279 AvahiResponseJob *rj;
284 for (rj = s->jobs; rj; rj = rj->jobs_next) {
285 assert(rj->state == AVAHI_SCHEDULED);
287 if (avahi_record_equal_no_ttl(rj->record, record))
294 static AvahiResponseJob* find_history_job(AvahiResponseScheduler *s, AvahiRecord *record) {
295 AvahiResponseJob *rj;
300 for (rj = s->history; rj; rj = rj->jobs_next) {
301 assert(rj->state == AVAHI_DONE);
303 if (avahi_record_equal_no_ttl(rj->record, record)) {
304 /* Check whether this entry is outdated */
306 /* avahi_log_debug("history age: %u", (unsigned) (avahi_age(&rj->delivery)/1000)); */
308 if (avahi_age(&rj->delivery)/1000 > AVAHI_RESPONSE_HISTORY_MSEC) {
309 /* it is outdated, so let's remove it */
321 static AvahiResponseJob* find_suppressed_job(AvahiResponseScheduler *s, AvahiRecord *record, const AvahiAddress *querier) {
322 AvahiResponseJob *rj;
328 for (rj = s->suppressed; rj; rj = rj->jobs_next) {
329 assert(rj->state == AVAHI_SUPPRESSED);
330 assert(rj->querier_valid);
332 if (avahi_record_equal_no_ttl(rj->record, record) &&
333 avahi_address_cmp(&rj->querier, querier) == 0) {
334 /* Check whether this entry is outdated */
336 if (avahi_age(&rj->delivery) > AVAHI_RESPONSE_SUPPRESS_MSEC*1000) {
337 /* it is outdated, so let's remove it */
349 int avahi_response_scheduler_post(AvahiResponseScheduler *s, AvahiRecord *record, int flush_cache, const AvahiAddress *querier, int immediately) {
350 AvahiResponseJob *rj;
357 assert(!avahi_key_is_pattern(record->key));
359 /* t = avahi_record_to_string(record); */
360 /* avahi_log_debug("post %i %s", immediately, t); */
363 /* Check whether this response is suppressed */
365 (rj = find_suppressed_job(s, record, querier)) &&
366 avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) &&
367 rj->record->ttl >= record->ttl/2) {
369 /* avahi_log_debug("Response suppressed by known answer suppression."); */
373 /* Check if we already sent this response recently */
374 if ((rj = find_history_job(s, record))) {
376 if (avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) &&
377 rj->record->ttl >= record->ttl/2 &&
378 (rj->flush_cache || !flush_cache)) {
379 /* avahi_log_debug("Response suppressed by local duplicate suppression (history)"); */
387 avahi_elapse_time(&tv, immediately ? 0 : AVAHI_RESPONSE_DEFER_MSEC, immediately ? 0 : AVAHI_RESPONSE_JITTER_MSEC);
389 if ((rj = find_scheduled_job(s, record))) {
390 /* avahi_log_debug("Response suppressed by local duplicate suppression (scheduled)"); */
392 /* Update a little ... */
394 /* Update the time if the new is prior to the old */
395 if (avahi_timeval_compare(&tv, &rj->delivery) < 0) {
397 avahi_time_event_update(rj->time_event, &rj->delivery);
400 /* Update the flush cache bit */
404 /* Update the querier field */
405 if (!querier || (rj->querier_valid && avahi_address_cmp(querier, &rj->querier) != 0))
406 rj->querier_valid = 0;
408 /* Update record data (just for the TTL) */
409 avahi_record_unref(rj->record);
410 rj->record = avahi_record_ref(record);
414 /* avahi_log_debug("Accepted new response job."); */
416 /* Create a new job and schedule it */
417 if (!(rj = job_new(s, record, AVAHI_SCHEDULED)))
421 rj->time_event = avahi_time_event_new(s->time_event_queue, &rj->delivery, elapse_callback, rj);
422 rj->flush_cache = flush_cache;
424 if ((rj->querier_valid = !!querier))
425 rj->querier = *querier;
431 void avahi_response_scheduler_incoming(AvahiResponseScheduler *s, AvahiRecord *record, int flush_cache) {
432 AvahiResponseJob *rj;
435 /* This function is called whenever an incoming response was
436 * receieved. We drop scheduled responses which match here. The
437 * keyword is "DUPLICATE ANSWER SUPPRESION". */
439 if ((rj = find_scheduled_job(s, record))) {
441 if ((!rj->flush_cache || flush_cache) && /* flush cache bit was set correctly */
442 avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) && /* both goodbye packets, or both not */
443 record->ttl >= rj->record->ttl/2) { /* sensible TTL */
445 /* A matching entry was found, so let's mark it done */
446 /* avahi_log_debug("Response suppressed by distributed duplicate suppression"); */
447 job_mark_done(s, rj);
453 if ((rj = find_history_job(s, record))) {
454 /* Found a history job, let's update it */
455 avahi_record_unref(rj->record);
456 rj->record = avahi_record_ref(record);
458 /* Found no existing history job, so let's create a new one */
459 if (!(rj = job_new(s, record, AVAHI_DONE)))
462 rj->flush_cache = flush_cache;
463 rj->querier_valid = 0;
465 gettimeofday(&rj->delivery, NULL);
466 job_set_elapse_time(s, rj, AVAHI_RESPONSE_HISTORY_MSEC, 0);
469 void avahi_response_scheduler_suppress(AvahiResponseScheduler *s, AvahiRecord *record, const AvahiAddress *querier) {
470 AvahiResponseJob *rj;
476 if ((rj = find_scheduled_job(s, record))) {
478 if (rj->querier_valid && avahi_address_cmp(querier, &rj->querier) == 0 && /* same originator */
479 avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) && /* both goodbye packets, or both not */
480 record->ttl >= rj->record->ttl/2) { /* sensible TTL */
482 /* A matching entry was found, so let's drop it */
483 /* avahi_log_debug("Known answer suppression active!"); */
488 if ((rj = find_suppressed_job(s, record, querier))) {
490 /* Let's update the old entry */
491 avahi_record_unref(rj->record);
492 rj->record = avahi_record_ref(record);
496 /* Create a new entry */
497 if (!(rj = job_new(s, record, AVAHI_SUPPRESSED)))
499 rj->querier_valid = 1;
500 rj->querier = *querier;
503 gettimeofday(&rj->delivery, NULL);
504 job_set_elapse_time(s, rj, AVAHI_RESPONSE_SUPPRESS_MSEC, 0);
507 void avahi_response_scheduler_force(AvahiResponseScheduler *s) {
510 /* Send all scheduled responses immediately */
512 send_response_packet(s, s->jobs);