* split packet scheduler into three seperate parts

* test against Aplle test suit, most tests pass now
* suppress auxiliary records by known answers
* handle very large records


git-svn-id: file:///home/lennart/svn/public/avahi/trunk@74 941a03a8-eaeb-0310-b9a0-b1bbd8fe43fe

1 files changed, 482 insertions, 0 deletions

diff --git a/avahi-core/response-sched.c b/avahi-core/response-sched.c
new file mode 100644
index 0000000..c4218eb
--- /dev/null
+++ b/avahi-core/response-sched.c
@@ -0,0 +1,482 @@
+/* $Id$ */
+
+/***
+  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 "response-sched.h"
+#include "util.h"
+
+#define AVAHI_RESPONSE_HISTORY_MSEC 700
+#define AVAHI_RESPONSE_DEFER_MSEC 20
+#define AVAHI_RESPONSE_JITTER_MSEC 100
+#define AVAHI_RESPONSE_SUPPRESS_MSEC 700
+
+typedef struct AvahiResponseJob AvahiResponseJob;
+
+typedef enum {
+    AVAHI_SCHEDULED,
+    AVAHI_DONE,
+    AVAHI_SUPPRESSED
+} AvahiResponseJobState;
+
+struct AvahiResponseJob {
+    AvahiResponseScheduler *scheduler;
+    AvahiTimeEvent *time_event;
+    
+    AvahiResponseJobState state;
+    GTimeVal delivery;
+
+    AvahiRecord *record;
+    gboolean flush_cache;
+    AvahiAddress querier;
+    gboolean querier_valid;
+    
+    AVAHI_LLIST_FIELDS(AvahiResponseJob, jobs);
+};
+
+struct AvahiResponseScheduler {
+    AvahiInterface *interface;
+    AvahiTimeEventQueue *time_event_queue;
+
+    AVAHI_LLIST_HEAD(AvahiResponseJob, jobs);
+    AVAHI_LLIST_HEAD(AvahiResponseJob, history);
+    AVAHI_LLIST_HEAD(AvahiResponseJob, suppressed);
+};
+
+static AvahiResponseJob* job_new(AvahiResponseScheduler *s, AvahiRecord *record, AvahiResponseJobState state) {
+    AvahiResponseJob *rj;
+    
+    g_assert(s);
+    g_assert(record);
+
+    rj = g_new(AvahiResponseJob, 1);
+    rj->scheduler = s;
+    rj->record = avahi_record_ref(record);
+    rj->time_event = NULL;
+    rj->flush_cache = FALSE;
+    rj->querier_valid = FALSE;
+    
+    if ((rj->state = state) == AVAHI_SCHEDULED) 
+        AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->jobs, rj);
+    else if (rj->state == AVAHI_DONE)
+        AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->history, rj);
+    else  /* rj->state == AVAHI_SUPPRESSED */
+        AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->suppressed, rj);
+
+    return rj;
+}
+
+static void job_free(AvahiResponseScheduler *s, AvahiResponseJob *rj) {
+    g_assert(s);
+    g_assert(rj);
+
+    if (rj->time_event)
+        avahi_time_event_queue_remove(s->time_event_queue, rj->time_event);
+
+    if (rj->state == AVAHI_SCHEDULED)
+        AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->jobs, rj);
+    else if (rj->state == AVAHI_DONE)
+        AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->history, rj);
+    else /* rj->state == AVAHI_SUPPRESSED */
+        AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->suppressed, rj);
+
+    avahi_record_unref(rj->record);
+    g_free(rj);
+}
+
+static void elapse_callback(AvahiTimeEvent *e, gpointer data);
+
+static void job_set_elapse_time(AvahiResponseScheduler *s, AvahiResponseJob *rj, guint msec, guint jitter) {
+    GTimeVal tv;
+
+    g_assert(s);
+    g_assert(rj);
+
+    avahi_elapse_time(&tv, msec, jitter);
+
+    if (rj->time_event)
+        avahi_time_event_queue_update(s->time_event_queue, rj->time_event, &tv);
+    else
+        rj->time_event = avahi_time_event_queue_add(s->time_event_queue, &tv, elapse_callback, rj);
+}
+
+static void job_mark_done(AvahiResponseScheduler *s, AvahiResponseJob *rj) {
+    g_assert(s);
+    g_assert(rj);
+
+    g_assert(rj->state == AVAHI_SCHEDULED);
+
+    AVAHI_LLIST_REMOVE(AvahiResponseJob, jobs, s->jobs, rj);
+    AVAHI_LLIST_PREPEND(AvahiResponseJob, jobs, s->history, rj);
+
+    rj->state = AVAHI_DONE;
+
+    job_set_elapse_time(s, rj, AVAHI_RESPONSE_HISTORY_MSEC, 0);
+
+    g_get_current_time(&rj->delivery);
+}
+
+AvahiResponseScheduler *avahi_response_scheduler_new(AvahiInterface *i) {
+    AvahiResponseScheduler *s;
+    g_assert(i);
+
+    s = g_new(AvahiResponseScheduler, 1);
+    s->interface = i;
+    s->time_event_queue = i->monitor->server->time_event_queue;
+    
+    AVAHI_LLIST_HEAD_INIT(AvahiResponseJob, s->jobs);
+    AVAHI_LLIST_HEAD_INIT(AvahiResponseJob, s->history);
+    AVAHI_LLIST_HEAD_INIT(AvahiResponseJob, s->suppressed);
+
+    return s;
+}
+
+void avahi_response_scheduler_free(AvahiResponseScheduler *s) {
+    g_assert(s);
+
+    avahi_response_scheduler_clear(s);
+    g_free(s);
+}
+
+void avahi_response_scheduler_clear(AvahiResponseScheduler *s) {
+    g_assert(s);
+    
+    while (s->jobs)
+        job_free(s, s->jobs);
+    while (s->history)
+        job_free(s, s->history);
+    while (s->suppressed)
+        job_free(s, s->suppressed);
+}
+
+static void enumerate_aux_records_callback(AvahiServer *s, AvahiRecord *r, gboolean flush_cache, gpointer userdata) {
+    AvahiResponseJob *rj = userdata;
+    
+    g_assert(r);
+    g_assert(rj);
+
+    avahi_response_scheduler_post(rj->scheduler, r, flush_cache, rj->querier_valid ? &rj->querier : NULL, FALSE);
+}
+
+static gboolean packet_add_response_job(AvahiResponseScheduler *s, AvahiDnsPacket *p, AvahiResponseJob *rj) {
+    g_assert(s);
+    g_assert(p);
+    g_assert(rj);
+
+    /* Try to add this record to the packet */
+    if (!avahi_dns_packet_append_record(p, rj->record, rj->flush_cache, 0))
+        return FALSE;
+
+    /* Ok, this record will definitely be sent, so schedule the
+     * auxilliary packets, too */
+    avahi_server_enumerate_aux_records(s->interface->monitor->server, s->interface, rj->record, enumerate_aux_records_callback, rj);
+    job_mark_done(s, rj);
+    
+    return TRUE;
+}
+
+static void send_response_packet(AvahiResponseScheduler *s, AvahiResponseJob *rj) {
+    AvahiDnsPacket *p;
+    guint n;
+
+    g_assert(s);
+    g_assert(rj);
+
+    p = avahi_dns_packet_new_response(s->interface->hardware->mtu, TRUE);
+    n = 1;
+
+    /* Put it in the packet. */
+    if (packet_add_response_job(s, p, rj)) {
+
+        /* Try to fill up packet with more responses, if available */
+        while (s->jobs) {
+            
+            if (!packet_add_response_job(s, p, s->jobs))
+                break;
+            
+            n++;
+        }
+        
+    } else {
+        guint size;
+        
+        avahi_dns_packet_free(p);
+
+        /* OK, the packet was too small, so create one that fits */
+        size = avahi_record_get_estimate_size(rj->record) + AVAHI_DNS_PACKET_HEADER_SIZE;
+
+        if (size > AVAHI_DNS_PACKET_MAX_SIZE)
+            size = AVAHI_DNS_PACKET_MAX_SIZE;
+        
+        p = avahi_dns_packet_new_response(size, TRUE);
+
+        if (!packet_add_response_job(s, p, rj)) {
+            avahi_dns_packet_free(p);
+
+            g_warning("Record too large, cannot send");
+            job_mark_done(s, rj);
+            return;
+        }
+    }
+
+    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) {
+    AvahiResponseJob *rj = data;
+
+    g_assert(rj);
+
+    if (rj->state == AVAHI_DONE || rj->state == AVAHI_SUPPRESSED) 
+        job_free(rj->scheduler, rj);         /* Lets drop this entry */
+    else
+        send_response_packet(rj->scheduler, rj);
+}
+
+static AvahiResponseJob* find_scheduled_job(AvahiResponseScheduler *s, AvahiRecord *record) {
+    AvahiResponseJob *rj;
+
+    g_assert(s);
+    g_assert(record);
+
+    for (rj = s->jobs; rj; rj = rj->jobs_next) {
+        g_assert(rj->state == AVAHI_SCHEDULED);
+    
+        if (avahi_record_equal_no_ttl(rj->record, record))
+            return rj;
+    }
+
+    return NULL;
+}
+
+static AvahiResponseJob* find_history_job(AvahiResponseScheduler *s, AvahiRecord *record) {
+    AvahiResponseJob *rj;
+    
+    g_assert(s);
+    g_assert(record);
+
+    for (rj = s->history; rj; rj = rj->jobs_next) {
+        g_assert(rj->state == AVAHI_DONE);
+
+        if (avahi_record_equal_no_ttl(rj->record, record)) {
+            /* Check whether this entry is outdated */
+
+            if (avahi_age(&rj->delivery) > AVAHI_RESPONSE_HISTORY_MSEC*1000) {
+                /* it is outdated, so let's remove it */
+                job_free(s, rj);
+                return NULL;
+            }
+                
+            return rj;
+        }
+    }
+
+    return NULL;
+}
+
+static AvahiResponseJob* find_suppressed_job(AvahiResponseScheduler *s, AvahiRecord *record, const AvahiAddress *querier) {
+    AvahiResponseJob *rj;
+    
+    g_assert(s);
+    g_assert(record);
+    g_assert(querier);
+
+    for (rj = s->suppressed; rj; rj = rj->jobs_next) {
+        g_assert(rj->state == AVAHI_SUPPRESSED);
+        g_assert(rj->querier_valid);
+        
+        if (avahi_record_equal_no_ttl(rj->record, record) &&
+            avahi_address_cmp(&rj->querier, querier) == 0) {
+            /* Check whether this entry is outdated */
+
+            if (avahi_age(&rj->delivery) > AVAHI_RESPONSE_SUPPRESS_MSEC*1000) {
+                /* it is outdated, so let's remove it */
+                job_free(s, rj);
+                return NULL;
+            }
+
+            return rj;
+        }
+    }
+
+    return NULL;
+}
+
+gboolean avahi_response_scheduler_post(AvahiResponseScheduler *s, AvahiRecord *record, gboolean flush_cache, const AvahiAddress *querier, gboolean immediately) {
+    AvahiResponseJob *rj;
+    GTimeVal tv;
+    
+    g_assert(s);
+    g_assert(record);
+
+    g_assert(!avahi_key_is_pattern(record->key));
+
+    /* Check whether this response is suppressed */
+    if (querier &&
+        (rj = find_suppressed_job(s, record, querier)) &&
+        avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) &&
+        rj->record->ttl >= record->ttl/2) {
+
+        g_message("Response suppressed by known answer suppression.");
+        return FALSE;
+    }
+
+    /* Check if we already sent this response recently */
+    if ((rj = find_history_job(s, record))) {
+
+        if (avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) &&
+            rj->record->ttl >= record->ttl/2 &&
+            (rj->flush_cache || !flush_cache)) {
+            g_message("Response suppressed by local duplicate suppression (history)");
+            return FALSE;
+        }
+
+        /* Outdated ... */
+        job_free(s, rj);
+    }
+
+    avahi_elapse_time(&tv, immediately ? 0 : AVAHI_RESPONSE_DEFER_MSEC, immediately ? 0 : AVAHI_RESPONSE_JITTER_MSEC);
+         
+    if ((rj = find_scheduled_job(s, record))) {
+        g_message("Response suppressed by local duplicate suppression (scheduled)");
+
+        /* Update a little ... */
+
+        /* Update the time if the new is prior to the old */
+        if (avahi_timeval_compare(&tv, &rj->delivery) < 0) {
+            rj->delivery = tv;
+            avahi_time_event_queue_update(s->time_event_queue, rj->time_event, &rj->delivery);
+        }
+
+        /* Update the flush cache bit */
+        if (flush_cache)
+            rj->flush_cache = TRUE;
+
+        /* Update the querier field */
+        if (!querier || (rj->querier_valid && avahi_address_cmp(querier, &rj->querier) != 0))
+            rj->querier_valid = FALSE;
+
+        /* Update record data (just for the TTL) */
+        avahi_record_unref(rj->record);
+        rj->record = avahi_record_ref(record);
+
+        return TRUE;
+    } else {
+        g_message("Accepted new response job.");
+
+        /* Create a new job and schedule it */
+        rj = job_new(s, record, AVAHI_SCHEDULED);
+        rj->delivery = tv;
+        rj->time_event = avahi_time_event_queue_add(s->time_event_queue, &rj->delivery, elapse_callback, rj);
+        rj->flush_cache = flush_cache;
+
+        if ((rj->querier_valid = !!querier))
+            rj->querier = *querier;
+
+        return TRUE;
+    }
+}
+
+void avahi_response_scheduler_incoming(AvahiResponseScheduler *s, AvahiRecord *record, gboolean flush_cache) {
+    AvahiResponseJob *rj;
+    g_assert(s);
+
+    /* This function is called whenever an incoming response was
+     * receieved. We drop scheduled responses which match here. The
+     * keyword is "DUPLICATE ANSWER SUPPRESION". */
+    
+    if ((rj = find_scheduled_job(s, record))) {
+
+        if ((!rj->flush_cache || flush_cache) &&    /* flush cache bit was set correctly */
+            avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) &&   /* both goodbye packets, or both not */
+            record->ttl >= rj->record->ttl/2) {     /* sensible TTL */
+
+            /* A matching entry was found, so let's mark it done */
+            g_message("Response suppressed by distributed duplicate suppression");
+            job_mark_done(s, rj);
+        }
+
+        return;
+    }
+
+    if ((rj = find_history_job(s, record))) {
+        /* Found a history job, let's update it */
+        avahi_record_unref(rj->record);
+        rj->record = avahi_record_ref(record);
+    } else
+        /* Found no existing history job, so let's create a new one */
+        rj = job_new(s, record, AVAHI_DONE);
+
+    rj->flush_cache = flush_cache;
+    rj->querier_valid = FALSE;
+    
+    g_get_current_time(&rj->delivery);
+    job_set_elapse_time(s, rj, AVAHI_RESPONSE_HISTORY_MSEC, 0);
+}
+
+void avahi_response_scheduler_suppress(AvahiResponseScheduler *s, AvahiRecord *record, const AvahiAddress *querier) {
+    AvahiResponseJob *rj;
+    
+    g_assert(s);
+    g_assert(record);
+    g_assert(querier);
+
+    if ((rj = find_scheduled_job(s, record))) {
+        
+        if (rj->querier_valid && avahi_address_cmp(querier, &rj->querier) == 0 && /* same originator */
+            avahi_record_is_goodbye(record) == avahi_record_is_goodbye(rj->record) && /* both goodbye packets, or both not */
+            record->ttl >= rj->record->ttl/2) {                                  /* sensible TTL */
+
+            /* A matching entry was found, so let's drop it */
+            g_message("Known answer suppression active!");
+            job_free(s, rj);
+        }
+    }
+
+    if ((rj = find_suppressed_job(s, record, querier))) {
+
+        /* Let's update the old entry */
+        avahi_record_unref(rj->record);
+        rj->record = avahi_record_ref(record);
+        
+    } else {
+
+        /* Create a new entry */
+        rj = job_new(s, record, AVAHI_SUPPRESSED);
+        rj->querier_valid = TRUE;
+        rj->querier = *querier;
+    }
+
+    g_get_current_time(&rj->delivery);
+    job_set_elapse_time(s, rj, AVAHI_RESPONSE_SUPPRESS_MSEC, 0);
+}
+
+void avahi_response_scheduler_force(AvahiResponseScheduler *s) {
+    g_assert(s);
+
+    /* Send all scheduled responses immediately */
+    while (s->jobs)
+        send_response_packet(s, s->jobs);
+}