--- /dev/null
+/* $Id$ */
+
+/***
+ This file is part of avahi.
+
+ avahi is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ avahi is distributed in the hope that it will be useful, but WITHOUT
+ ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
+ or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
+ Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public
+ License along with avahi; if not, write to the Free Software
+ Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
+ USA.
+***/
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include "query-sched.h"
+#include "util.h"
+
+#define AVAHI_QUERY_HISTORY_MSEC 100
+#define AVAHI_QUERY_DEFER_MSEC 100
+
+typedef struct AvahiQueryJob AvahiQueryJob;
+typedef struct AvahiKnownAnswer AvahiKnownAnswer;
+
+struct AvahiQueryJob {
+ AvahiQueryScheduler *scheduler;
+ AvahiTimeEvent *time_event;
+
+ gboolean done;
+ GTimeVal delivery;
+
+ AvahiKey *key;
+
+ AVAHI_LLIST_FIELDS(AvahiQueryJob, jobs);
+};
+
+struct AvahiKnownAnswer {
+ AvahiQueryScheduler *scheduler;
+ AvahiRecord *record;
+
+ AVAHI_LLIST_FIELDS(AvahiKnownAnswer, known_answer);
+};
+
+struct AvahiQueryScheduler {
+ AvahiInterface *interface;
+ AvahiTimeEventQueue *time_event_queue;
+
+ AVAHI_LLIST_HEAD(AvahiQueryJob, jobs);
+ AVAHI_LLIST_HEAD(AvahiQueryJob, history);
+ AVAHI_LLIST_HEAD(AvahiKnownAnswer, known_answers);
+};
+
+static AvahiQueryJob* job_new(AvahiQueryScheduler *s, AvahiKey *key, gboolean done) {
+ AvahiQueryJob *qj;
+
+ g_assert(s);
+ g_assert(key);
+
+ qj = g_new(AvahiQueryJob, 1);
+ qj->scheduler = s;
+ qj->key = avahi_key_ref(key);
+ qj->time_event = NULL;
+
+ if ((qj->done = done))
+ AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj);
+ else
+ AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->jobs, qj);
+
+ return qj;
+}
+
+static void job_free(AvahiQueryScheduler *s, AvahiQueryJob *qj) {
+ g_assert(s);
+ g_assert(qj);
+
+ if (qj->time_event)
+ avahi_time_event_queue_remove(s->time_event_queue, qj->time_event);
+
+ if (qj->done)
+ AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->history, qj);
+ else
+ AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->jobs, qj);
+
+ avahi_key_unref(qj->key);
+ g_free(qj);
+}
+
+static void elapse_callback(AvahiTimeEvent *e, gpointer data);
+
+static void job_set_elapse_time(AvahiQueryScheduler *s, AvahiQueryJob *qj, guint msec, guint jitter) {
+ GTimeVal tv;
+
+ g_assert(s);
+ g_assert(qj);
+
+ avahi_elapse_time(&tv, msec, jitter);
+
+ if (qj->time_event)
+ avahi_time_event_queue_update(s->time_event_queue, qj->time_event, &tv);
+ else
+ qj->time_event = avahi_time_event_queue_add(s->time_event_queue, &tv, elapse_callback, qj);
+}
+
+static void job_mark_done(AvahiQueryScheduler *s, AvahiQueryJob *qj) {
+ g_assert(s);
+ g_assert(qj);
+
+ g_assert(!qj->done);
+
+ AVAHI_LLIST_REMOVE(AvahiQueryJob, jobs, s->jobs, qj);
+ AVAHI_LLIST_PREPEND(AvahiQueryJob, jobs, s->history, qj);
+
+ qj->done = TRUE;
+
+ job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0);
+ g_get_current_time(&qj->delivery);
+}
+
+AvahiQueryScheduler *avahi_query_scheduler_new(AvahiInterface *i) {
+ AvahiQueryScheduler *s;
+ g_assert(i);
+
+ s = g_new(AvahiQueryScheduler, 1);
+ s->interface = i;
+ s->time_event_queue = i->monitor->server->time_event_queue;
+
+ AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->jobs);
+ AVAHI_LLIST_HEAD_INIT(AvahiQueryJob, s->history);
+ AVAHI_LLIST_HEAD_INIT(AvahiKnownAnswer, s->known_answers);
+
+ return s;
+}
+
+void avahi_query_scheduler_free(AvahiQueryScheduler *s) {
+ g_assert(s);
+
+ g_assert(!s->known_answers);
+ avahi_query_scheduler_clear(s);
+ g_free(s);
+}
+
+void avahi_query_scheduler_clear(AvahiQueryScheduler *s) {
+ g_assert(s);
+
+ while (s->jobs)
+ job_free(s, s->jobs);
+ while (s->history)
+ job_free(s, s->history);
+}
+
+static gpointer known_answer_walk_callback(AvahiCache *c, AvahiKey *pattern, AvahiCacheEntry *e, gpointer userdata) {
+ AvahiQueryScheduler *s = userdata;
+ AvahiKnownAnswer *ka;
+
+ g_assert(c);
+ g_assert(pattern);
+ g_assert(e);
+ g_assert(s);
+
+ if (avahi_cache_entry_half_ttl(c, e))
+ return NULL;
+
+ ka = g_new0(AvahiKnownAnswer, 1);
+ ka->scheduler = s;
+ ka->record = avahi_record_ref(e->record);
+
+ AVAHI_LLIST_PREPEND(AvahiKnownAnswer, known_answer, s->known_answers, ka);
+ return NULL;
+}
+
+static gboolean packet_add_query_job(AvahiQueryScheduler *s, AvahiDnsPacket *p, AvahiQueryJob *qj) {
+ g_assert(s);
+ g_assert(p);
+ g_assert(qj);
+
+ if (!avahi_dns_packet_append_key(p, qj->key, FALSE))
+ return FALSE;
+
+ /* Add all matching known answers to the list */
+ avahi_cache_walk(s->interface->cache, qj->key, known_answer_walk_callback, s);
+
+ job_mark_done(s, qj);
+
+ return TRUE;
+}
+
+static void append_known_answers_and_send(AvahiQueryScheduler *s, AvahiDnsPacket *p) {
+ AvahiKnownAnswer *ka;
+ guint n;
+ g_assert(s);
+ g_assert(p);
+
+ n = 0;
+
+ while ((ka = s->known_answers)) {
+ gboolean too_large = FALSE;
+
+ while (!avahi_dns_packet_append_record(p, ka->record, FALSE, 0)) {
+
+ if (avahi_dns_packet_is_empty(p)) {
+ /* The record is too large to fit into one packet, so
+ there's no point in sending it. Better is letting
+ the owner of the record send it as a response. This
+ has the advantage of a cache refresh. */
+
+ too_large = TRUE;
+ break;
+ }
+
+ avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_FLAGS, avahi_dns_packet_get_field(p, AVAHI_DNS_FIELD_FLAGS) | AVAHI_DNS_FLAG_TC);
+ avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n);
+ avahi_interface_send_packet(s->interface, p);
+ avahi_dns_packet_free(p);
+
+ p = avahi_dns_packet_new_query(s->interface->hardware->mtu);
+ n = 0;
+ }
+
+ AVAHI_LLIST_REMOVE(AvahiKnownAnswer, known_answer, s->known_answers, ka);
+ avahi_record_unref(ka->record);
+ g_free(ka);
+
+ if (!too_large)
+ n++;
+ }
+
+ avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_ANCOUNT, n);
+ avahi_interface_send_packet(s->interface, p);
+ avahi_dns_packet_free(p);
+}
+
+static void elapse_callback(AvahiTimeEvent *e, gpointer data) {
+ AvahiQueryJob *qj = data;
+ AvahiQueryScheduler *s;
+ AvahiDnsPacket *p;
+ guint n;
+ gboolean b;
+
+ g_assert(qj);
+ s = qj->scheduler;
+
+ if (qj->done) {
+ /* Lets remove it from the history */
+ job_free(s, qj);
+ return;
+ }
+
+ g_assert(!s->known_answers);
+
+ p = avahi_dns_packet_new_query(s->interface->hardware->mtu);
+ b = packet_add_query_job(s, p, qj);
+ g_assert(b); /* An query must always fit in */
+ n = 1;
+
+ /* Try to fill up packet with more queries, if available */
+ while (s->jobs) {
+
+ if (!packet_add_query_job(s, p, s->jobs))
+ break;
+
+ n++;
+ }
+
+ avahi_dns_packet_set_field(p, AVAHI_DNS_FIELD_QDCOUNT, n);
+
+ /* Now add known answers */
+ append_known_answers_and_send(s, p);
+}
+
+static AvahiQueryJob* find_scheduled_job(AvahiQueryScheduler *s, AvahiKey *key) {
+ AvahiQueryJob *qj;
+
+ g_assert(s);
+ g_assert(key);
+
+ for (qj = s->jobs; qj; qj = qj->jobs_next) {
+ g_assert(!qj->done);
+
+ if (avahi_key_equal(qj->key, key))
+ return qj;
+ }
+
+ return NULL;
+}
+
+static AvahiQueryJob* find_history_job(AvahiQueryScheduler *s, AvahiKey *key) {
+ AvahiQueryJob *qj;
+
+ g_assert(s);
+ g_assert(key);
+
+ for (qj = s->history; qj; qj = qj->jobs_next) {
+ g_assert(qj->done);
+
+ if (avahi_key_equal(qj->key, key)) {
+ /* Check whether this entry is outdated */
+
+ if (avahi_age(&qj->delivery) > AVAHI_QUERY_HISTORY_MSEC*1000) {
+ /* it is outdated, so let's remove it */
+ job_free(s, qj);
+ return NULL;
+ }
+
+ return qj;
+ }
+ }
+
+ return NULL;
+}
+
+gboolean avahi_query_scheduler_post(AvahiQueryScheduler *s, AvahiKey *key, gboolean immediately) {
+ GTimeVal tv;
+ AvahiQueryJob *qj;
+
+ g_assert(s);
+ g_assert(key);
+
+ if ((qj = find_history_job(s, key))) {
+ g_message("Query suppressed by local duplicate suppression (history)");
+ return FALSE;
+ }
+
+ avahi_elapse_time(&tv, immediately ? 0 : AVAHI_QUERY_DEFER_MSEC, 0);
+
+ if ((qj = find_scheduled_job(s, key))) {
+ /* Duplicate questions suppression */
+
+ g_message("Query suppressed by local duplicate suppression (scheduled)");
+
+ if (avahi_timeval_compare(&tv, &qj->delivery) < 0) {
+ /* If the new entry should be scheduled earlier,
+ * update the old entry */
+ qj->delivery = tv;
+ avahi_time_event_queue_update(s->time_event_queue, qj->time_event, &qj->delivery);
+ }
+
+ return TRUE;
+ } else {
+ g_message("Accepted new query job.\n");
+
+ qj = job_new(s, key, FALSE);
+ qj->delivery = tv;
+ qj->time_event = avahi_time_event_queue_add(s->time_event_queue, &qj->delivery, elapse_callback, qj);
+
+ return TRUE;
+ }
+}
+
+void avahi_query_scheduler_incoming(AvahiQueryScheduler *s, AvahiKey *key) {
+ AvahiQueryJob *qj;
+
+ g_assert(s);
+ g_assert(key);
+
+ /* This function is called whenever an incoming query was
+ * receieved. We drop scheduled queries that match. The keyword is
+ * "DUPLICATE QUESTION SUPPRESION". */
+
+ if ((qj = find_scheduled_job(s, key))) {
+ g_message("Query suppressed by distributed duplicate suppression");
+ job_mark_done(s, qj);
+ return;
+ }
+
+ qj = job_new(s, key, TRUE);
+ g_get_current_time(&qj->delivery);
+ job_set_elapse_time(s, qj, AVAHI_QUERY_HISTORY_MSEC, 0);
+}
+
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