EDNS fallback when timeout and multiple query rtt backoff.

git-svn-id: file:///svn/unbound/trunk@1272 be551aaa-1e26-0410-a405-d3ace91eadb9

doc/Changelog

@@ -1,3 +1,8 @@
+29 September 2008: Wouter
+	- EDNS lameness detection, if EDNS packets are dropped this is
+	  detected, eventually.
+	- multiple query timeout rtt backoff does not backoff too much.
+
 26 September 2008: Wouter
 	- tests for remote-control.
 	- small memory leak in exception during remote control fixed.

services/cache/infra.c

@@ -208,13 +208,15 @@ new_host_entry(struct infra_cache* infra, struct sockaddr_storage* addr,
 	data->ttl = tm + infra->host_ttl;
 	data->lameness = NULL;
 	data->edns_version = 0;
+	data->edns_lame_known = 0;
 	rtt_init(&data->rtt);
 	return &key->entry;
 }
 
 int 
 infra_host(struct infra_cache* infra, struct sockaddr_storage* addr,
-        socklen_t addrlen, uint32_t timenow, int* edns_vs, int* to)
+        socklen_t addrlen, uint32_t timenow, int* edns_vs, 
+	uint8_t* edns_lame_known, int* to)
 {
 	struct lruhash_entry* e = infra_lookup_host_nottl(infra, addr, 
 		addrlen, 0);
@@ -231,6 +233,7 @@ infra_host(struct infra_cache* infra, struct sockaddr_storage* addr,
 			rtt_init(&data->rtt);
 			/* do not touch lameness, it may be valid still */
 			data->edns_version = 0;
+			data->edns_lame_known = 0;
 		}
 	}
 	if(!e) {
@@ -240,6 +243,7 @@ infra_host(struct infra_cache* infra, struct sockaddr_storage* addr,
 		data = (struct infra_host_data*)e->data;
 		*to = rtt_timeout(&data->rtt);
 		*edns_vs = data->edns_version;
+		*edns_lame_known = data->edns_lame_known;
 		slabhash_insert(infra->hosts, e->hash, e, data, NULL);
 		return 1;
 	}
@@ -247,6 +251,7 @@ infra_host(struct infra_cache* infra, struct sockaddr_storage* addr,
 	data = (struct infra_host_data*)e->data;
 	*to = rtt_timeout(&data->rtt);
 	*edns_vs = data->edns_version;
+	*edns_lame_known = data->edns_lame_known;
 	lock_rw_unlock(&e->lock);
 	return 1;
 }
@@ -438,7 +443,7 @@ infra_update_tcp_works(struct infra_cache* infra,
 int 
 infra_rtt_update(struct infra_cache* infra,
         struct sockaddr_storage* addr, socklen_t addrlen,
-        int roundtrip, uint32_t timenow)
+        int roundtrip, int orig_rtt, uint32_t timenow)
 {
 	struct lruhash_entry* e = infra_lookup_host_nottl(infra, addr, 
 		addrlen, 1);
@@ -454,7 +459,7 @@ infra_rtt_update(struct infra_cache* infra,
 	data = (struct infra_host_data*)e->data;
 	data->ttl = timenow + infra->host_ttl;
 	if(roundtrip == -1)
-		rtt_lost(&data->rtt);
+		rtt_lost(&data->rtt, orig_rtt);
 	else	rtt_update(&data->rtt, roundtrip);
 	if(data->rtt.rto > 0)
 		rto = data->rtt.rto;
@@ -483,6 +488,7 @@ infra_edns_update(struct infra_cache* infra,
 	data = (struct infra_host_data*)e->data;
 	data->ttl = timenow + infra->host_ttl;
 	data->edns_version = edns_version;
+	data->edns_lame_known = 1;
 
 	if(needtoinsert)
 		slabhash_insert(infra->hosts, e->hash, e, e->data, NULL);

services/cache/infra.h

@@ -70,6 +70,10 @@ struct infra_host_data {
 	struct lruhash* lameness;
 	/** edns version that the host supports, -1 means no EDNS */
 	int edns_version;
+	/** if the EDNS lameness is already known or not.
+	 * EDNS lame is when EDNS queries or replies are dropped, 
+	 * and cause a timeout */
+	uint8_t edns_lame_known;
 };
 
 /**
@@ -166,11 +170,14 @@ struct infra_host_data* infra_lookup_host(struct infra_cache* infra,
  * @param addrlen: length of addr.
  * @param timenow: what time it is now.
  * @param edns_vs: edns version it supports, is returned.
+ * @param edns_lame_known: if EDNS lame (EDNS is dropped in transit) has
+ * 	already been probed, is returned.
  * @param to: timeout to use, is returned.
  * @return: 0 on error.
  */
 int infra_host(struct infra_cache* infra, struct sockaddr_storage* addr, 
-	socklen_t addrlen, uint32_t timenow, int* edns_vs, int* to);
+	socklen_t addrlen, uint32_t timenow, int* edns_vs, 
+	uint8_t* edns_lame_known, int* to);
 
 /**
  * Check for lameness of this server for a particular zone.
@@ -213,12 +220,14 @@ int infra_set_lame(struct infra_cache* infra,
  * @param addrlen: length of addr.
  * @param roundtrip: estimate of roundtrip time in milliseconds or -1 for 
  * 	timeout.
+ * @param orig_rtt: original rtt for the query that timed out (roundtrip==-1).
+ * 	ignored if roundtrip != -1.
  * @param timenow: what time it is now.
  * @return: 0 on error. new rto otherwise.
  */
 int infra_rtt_update(struct infra_cache* infra,
         struct sockaddr_storage* addr, socklen_t addrlen,
-	int roundtrip, uint32_t timenow);
+	int roundtrip, int orig_rtt, uint32_t timenow);
 
 /**
  * Update information for the host, store that a TCP transaction works.

services/outside_network.c

@@ -1084,7 +1084,8 @@ serviced_delete(struct serviced_query* sq)
 	if(sq->pending) {
 		/* clear up the pending query */
 		if(sq->status == serviced_query_UDP_EDNS ||
-			sq->status == serviced_query_UDP) {
+			sq->status == serviced_query_UDP ||
+			sq->status == serviced_query_PROBE_EDNS) {
 			struct pending* p = (struct pending*)sq->pending;
 			if(p->pc)
 				portcomm_loweruse(sq->outnet, p->pc);
@@ -1184,18 +1185,30 @@ static int
 serviced_udp_send(struct serviced_query* sq, ldns_buffer* buff)
 {
 	int rtt, vs;
+	uint8_t edns_lame_known;
 	uint32_t now = *sq->outnet->now_secs;
 
 	if(!infra_host(sq->outnet->infra, &sq->addr, sq->addrlen, now, &vs,
-		&rtt))
+		&edns_lame_known, &rtt))
 		return 0;
 	if(sq->status == serviced_initial) {
-		if(vs != -1)
+		if(edns_lame_known == 0 && rtt > 5000) {
+			/* perform EDNS lame probe - check if server is
+			 * EDNS lame (EDNS queries to it are dropped) */
+			verbose(VERB_ALGO, "serviced query: send probe to see "
+				" if use of EDNS causes timeouts");
+			rtt /= 10;
+			sq->status = serviced_query_PROBE_EDNS;
+		} else if(vs != -1) {
 			sq->status = serviced_query_UDP_EDNS;
-		else 	sq->status = serviced_query_UDP;
+		} else { 	
+			sq->status = serviced_query_UDP; 
+		}
 	}
 	serviced_encode(sq, buff, sq->status == serviced_query_UDP_EDNS);
 	sq->last_sent_time = *sq->outnet->now_tv;
+	sq->last_rtt = rtt;
+	sq->edns_lame_known = (int)edns_lame_known;
 	verbose(VERB_ALGO, "serviced query UDP timeout=%d msec", rtt);
 	sq->pending = pending_udp_query(sq->outnet, buff, &sq->addr, 
 		sq->addrlen, rtt, serviced_udp_callback, sq);
@@ -1392,9 +1405,17 @@ serviced_udp_callback(struct comm_point* c, void* arg, int error,
 	sq->pending = NULL; /* removed after callback */
 	if(error == NETEVENT_TIMEOUT) {
 		int rto = 0;
+		if(sq->status == serviced_query_PROBE_EDNS) {
+			/* non-EDNS probe failed; not an EDNS lame server */
+			if(!infra_edns_update(outnet->infra, &sq->addr, 
+				sq->addrlen, 0, (uint32_t)now.tv_sec)) {
+				log_err("Out of memory caching edns works");
+			}
+			sq->status = serviced_query_UDP_EDNS;
+		}
 		sq->retry++;
 		if(!(rto=infra_rtt_update(outnet->infra, &sq->addr, sq->addrlen,
-			-1, (uint32_t)now.tv_sec)))
+			-1, sq->last_rtt, (uint32_t)now.tv_sec)))
 			log_err("out of memory in UDP exponential backoff");
 		if(sq->retry < OUTBOUND_UDP_RETRY) {
 			log_name_addr(VERB_ALGO, "retry query", sq->qbuf+10,
@@ -1439,6 +1460,25 @@ serviced_udp_callback(struct comm_point* c, void* arg, int error,
 		return 0;
 	}
 	/* yay! an answer */
+	if(sq->status == serviced_query_PROBE_EDNS) {
+		/* probe without EDNS succeeds, so we conclude that this
+		 * host likely has EDNS packets dropped */
+		log_addr(VERB_OPS, "timeouts, concluded that connection to "
+			"host drops EDNS packets", &sq->addr, sq->addrlen);
+		if(!infra_edns_update(outnet->infra, &sq->addr, sq->addrlen,
+			-1, (uint32_t)now.tv_sec)) {
+			log_err("Out of memory caching no edns for host");
+		}
+		sq->status = serviced_query_UDP;
+	} else if(sq->status == serviced_query_UDP_EDNS && 
+		!sq->edns_lame_known) {
+		/* now we know that edns queries received answers store that */
+		if(!infra_edns_update(outnet->infra, &sq->addr, sq->addrlen, 
+			0, (uint32_t)now.tv_sec)) {
+			log_err("Out of memory caching edns works");
+		}
+		sq->edns_lame_known = 1;
+	}
 	if(now.tv_sec > sq->last_sent_time.tv_sec ||
 		(now.tv_sec == sq->last_sent_time.tv_sec &&
 		now.tv_usec > sq->last_sent_time.tv_usec)) {
@@ -1448,7 +1488,7 @@ serviced_udp_callback(struct comm_point* c, void* arg, int error,
 		verbose(VERB_ALGO, "measured roundtrip at %d msec", roundtime);
 		log_assert(roundtime >= 0);
 		if(!infra_rtt_update(outnet->infra, &sq->addr, sq->addrlen, 
-			roundtime, (uint32_t)now.tv_sec))
+			roundtime, sq->last_rtt, (uint32_t)now.tv_sec))
 			log_err("out of memory noting rtt.");
 	}
 	serviced_callbacks(sq, error, c, rep);
@@ -1631,7 +1671,8 @@ serviced_get_mem(struct serviced_query* sq)
 	for(sb = sq->cblist; sb; sb = sb->next)
 		s += sizeof(*sb);
 	if(sq->status == serviced_query_UDP_EDNS ||
-		sq->status == serviced_query_UDP) {
+		sq->status == serviced_query_UDP ||
+		sq->status == serviced_query_PROBE_EDNS) {
 		s += sizeof(struct pending);
 		s += comm_timer_get_mem(NULL);
 	} else {

services/outside_network.h

@@ -294,7 +294,9 @@ struct serviced_query {
 		/** TCP with EDNS sent */
 		serviced_query_TCP_EDNS,
 		/** TCP without EDNS sent */
-		serviced_query_TCP
+		serviced_query_TCP,
+		/** probe to test EDNS lameness (EDNS is dropped) */
+		serviced_query_PROBE_EDNS
 	} 	
 		/** variable with current status */ 
 		status;
@@ -304,6 +306,10 @@ struct serviced_query {
 	int retry;
 	/** time last UDP was sent */
 	struct timeval last_sent_time;
+	/** rtt of last (UDP) message */
+	int last_rtt;
+	/** do we know edns probe status already, for UDP_EDNS queries */
+	int edns_lame_known;
 	/** outside network this is part of */
 	struct outside_network* outnet;
 	/** list of interested parties that need callback on results. */

testcode/ldns-testpkts.c

@@ -112,6 +112,8 @@ static void matchline(char* line, struct entry* e)
 			e->match_ttl = true;
 		} else if(str_keyword(&parse, "DO")) {
 			e->match_do = true;
+		} else if(str_keyword(&parse, "noedns")) {
+			e->match_noedns = true;
 		} else if(str_keyword(&parse, "UDP")) {
 			e->match_transport = transport_udp;
 		} else if(str_keyword(&parse, "TCP")) {
@@ -233,6 +235,7 @@ static struct entry* new_entry()
 	e->match_all = false;
 	e->match_ttl = false;
 	e->match_do = false;
+	e->match_noedns = false;
 	e->match_serial = false;
 	e->ixfr_soa_serial = 0;
 	e->match_transport = transport_any;
@@ -697,6 +700,10 @@ find_match(struct entry* entries, ldns_pkt* query_pkt,
 			verbose(3, "no DO bit set\n");
 			continue;
 		}
+		if(p->match_noedns && ldns_pkt_edns(query_pkt)) {
+			verbose(3, "bad; EDNS OPT present\n");
+			continue;
+		}
 		if(p->match_transport != transport_any && p->match_transport != transport) {
 			verbose(3, "bad transport\n");
 			continue;

testcode/ldns-testpkts.h

@@ -47,6 +47,7 @@
 	; 'all' has to match header byte for byte and all rrs in packet.
 	; 'ttl' used with all, rrs in packet must also have matching TTLs.
 	; 'DO' will match only queries with DO bit set.
+	; 'noedns' matches queries without EDNS OPT records.
 	MATCH [opcode] [qtype] [qname] [serial=<value>] [all] [ttl]
 	MATCH [UDP|TCP] DO
 	MATCH ...
@@ -168,6 +169,8 @@ struct entry {
 	bool match_ttl;
 	/** match DO bit */
 	bool match_do;
+	/** match absence of EDNS OPT record in query */
+	bool match_noedns;
 	/** match query serial with this value. */
 	uint32_t ixfr_soa_serial; 
 	/** match on UDP/TCP */

testcode/unitmain.c

@@ -289,15 +289,15 @@ rtt_test()
 	rtt_init(&r);
 	/* initial value sensible */
 	unit_assert( rtt_timeout(&r) == init );
-	rtt_lost(&r);
+	rtt_lost(&r, init);
 	unit_assert( rtt_timeout(&r) == init*2 );
-	rtt_lost(&r);
+	rtt_lost(&r, init*2);
 	unit_assert( rtt_timeout(&r) == init*4 );
 	rtt_update(&r, 4000);
 	unit_assert( rtt_timeout(&r) >= 2000 );
-	rtt_lost(&r);
+	rtt_lost(&r, rtt_timeout(&r) );
 	for(i=0; i<100; i++) {
-		rtt_lost(&r); 
+		rtt_lost(&r, rtt_timeout(&r) ); 
 		unit_assert( rtt_timeout(&r) > RTT_MIN_TIMEOUT-1);
 		unit_assert( rtt_timeout(&r) < RTT_MAX_TIMEOUT+1);
 	}
@@ -315,6 +315,7 @@ infra_test()
 	struct infra_cache* slab;
 	struct config_file* cfg = config_create();
 	uint32_t now = 0;
+	uint8_t edns_lame;
 	int vs, to;
 	struct infra_host_key* k;
 	struct infra_host_data* d;
@@ -323,25 +324,25 @@ infra_test()
 
 	slab = infra_create(cfg);
 	unit_assert( infra_host(slab, (struct sockaddr_storage*)&one, 
-		(socklen_t)sizeof(int), now, &vs, &to) );
-	unit_assert( vs == 0 && to == init );
+		(socklen_t)sizeof(int), now, &vs, &edns_lame, &to) );
+	unit_assert( vs == 0 && to == init && edns_lame == 0 );
 
 	unit_assert( infra_rtt_update(slab, (struct sockaddr_storage*)&one,
-		(socklen_t)sizeof(int), -1, now) );
+		(socklen_t)sizeof(int), -1, init, now) );
 	unit_assert( infra_host(slab, (struct sockaddr_storage*)&one, 
-		(socklen_t)sizeof(int), now, &vs, &to) );
-	unit_assert( vs == 0 && to == init*2 );
+		(socklen_t)sizeof(int), now, &vs, &edns_lame, &to) );
+	unit_assert( vs == 0 && to == init*2 && edns_lame == 0 );
 
 	unit_assert( infra_edns_update(slab, (struct sockaddr_storage*)&one,
 		(socklen_t)sizeof(int), -1, now) );
 	unit_assert( infra_host(slab, (struct sockaddr_storage*)&one, 
-		(socklen_t)sizeof(int), now, &vs, &to) );
-	unit_assert( vs == -1 && to == init*2 );
+		(socklen_t)sizeof(int), now, &vs, &edns_lame, &to) );
+	unit_assert( vs == -1 && to == init*2  && edns_lame == 1);
 
 	now += cfg->host_ttl + 10;
 	unit_assert( infra_host(slab, (struct sockaddr_storage*)&one, 
-		(socklen_t)sizeof(int), now, &vs, &to) );
-	unit_assert( vs == 0 && to == init );
+		(socklen_t)sizeof(int), now, &vs, &edns_lame, &to) );
+	unit_assert( vs == 0 && to == init && edns_lame == 0 );
 	
 	unit_assert( infra_set_lame(slab, (struct sockaddr_storage*)&one, 
 		(socklen_t)sizeof(int), zone, zonelen,  now, 0, 

util/rtt.c

@@ -95,10 +95,17 @@ rtt_update(struct rtt_info* rtt, int ms)
 }
 
 void 
-rtt_lost(struct rtt_info* rtt)
+rtt_lost(struct rtt_info* rtt, int orig)
 {
 	/* exponential backoff */
-	rtt->rto *= 2;
-	if(rtt->rto > RTT_MAX_TIMEOUT)
-		rtt->rto = RTT_MAX_TIMEOUT;
+
+	/* the original rto is doubled, not the current one to make sure
+	 * that the values in the cache are not increased by lots of
+	 * queries simultaneously as they time out at the same time */
+	orig *= 2;
+	if(rtt->rto <= orig) {
+		rtt->rto = orig;
+		if(rtt->rto > RTT_MAX_TIMEOUT)
+			rtt->rto = RTT_MAX_TIMEOUT;
+	}
 }

util/rtt.h

@@ -91,7 +91,10 @@ void rtt_update(struct rtt_info* rtt, int ms);
 /**
  * Update the statistics with a new timout expired observation.
  * @param rtt: round trip statistics structure.
+ * @param orig: original rtt time given for the query that timed out.
+ * 	Used to calculate the maximum responsible backed off time that
+ * 	can reasonably be applied.
  */
-void rtt_lost(struct rtt_info* rtt);
+void rtt_lost(struct rtt_info* rtt, int orig);
 
 #endif /* UTIL_RTT_H */