From: Grigorii Demidov <grigorii.demidov@nic.cz>
Date: Thu, 7 Sep 2017 12:07:13 +0000 (+0200)
Subject: lib: support of an upper limit for resolution time of single query
X-Git-Tag: v1.4.0~7^2~2
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=aa813a08eb325ca2ec2e65628b826a5d3da45ec4;p=thirdparty%2Fknot-resolver.git

lib: support of an upper limit for resolution time of single query
---

diff --git a/lib/defines.h b/lib/defines.h
index 2621a7ac3..b74a16d33 100644
--- a/lib/defines.h
+++ b/lib/defines.h
@@ -58,6 +58,7 @@ static inline int __attribute__((__cold__)) kr_error(int x) {
 #define KR_CONN_RTT_MAX 3000 /* Timeout for network activity */
 #define KR_CONN_RETRY 250    /* Retry interval for network activity */
 #define KR_ITER_LIMIT 100    /* Built-in iterator limit */
+#define KR_RESOLVE_TIME_LIMIT 10000 /* Upper limit for resolution time of single query, ms */
 #define KR_CNAME_CHAIN_LIMIT 40 /* Built-in maximum CNAME chain length */
 #define KR_TIMEOUT_LIMIT 4   /* Maximum number of retries after timeout. */
 #define KR_QUERY_NSRETRY_LIMIT 4 /* Maximum number of retries per query. */
diff --git a/lib/resolve.c b/lib/resolve.c
index 8a85f8453..cd60412d8 100644
--- a/lib/resolve.c
+++ b/lib/resolve.c
@@ -874,6 +874,15 @@ int kr_resolve_consume(struct kr_request *request, const struct sockaddr *src, k
 
 	/* Different processing for network error */
 	struct kr_query *qry = array_tail(rplan->pending);
+	struct timeval now;
+	gettimeofday(&now, NULL);
+	unsigned resolving_time = time_diff(&qry->creation_time, &now);
+	if (resolving_time > KR_RESOLVE_TIME_LIMIT) {
+		WITH_VERBOSE {
+			VERBOSE_MSG(qry, "query resolution time limit exceeded %i\n", resolving_time);
+		}
+		return KR_STATE_FAIL;
+	}
 	bool tried_tcp = (qry->flags.TCP);
 	if (!packet || packet->size == 0) {
 		if (tried_tcp) {
@@ -891,8 +900,6 @@ int kr_resolve_consume(struct kr_request *request, const struct sockaddr *src, k
 		if (qry->flags.CACHED) {
 			ITERATE_LAYERS(request, qry, consume, packet);
 		} else {
-			struct timeval now;
-			gettimeofday(&now, NULL);
 			/* Fill in source and latency information. */
 			request->upstream.rtt = time_diff(&qry->timestamp, &now);
 			request->upstream.addr = src;
diff --git a/lib/rplan.c b/lib/rplan.c
index b78e41835..9b218c0a8 100644
--- a/lib/rplan.c
+++ b/lib/rplan.c
@@ -154,6 +154,7 @@ static struct kr_query *kr_rplan_push_query(struct kr_rplan *rplan,
 	qry->ns.ctx = rplan->request->ctx;
 	qry->ns.addr[0].ip.sa_family = AF_UNSPEC;
 	gettimeofday(&qry->timestamp, NULL);
+	qry->creation_time = qry->timestamp;
 	kr_zonecut_init(&qry->zone_cut, (const uint8_t *)"", rplan->pool);
 	qry->reorder = qry->flags.REORDER_RR
 		? knot_wire_get_id(rplan->request->answer->wire)
diff --git a/lib/rplan.h b/lib/rplan.h
index af35bd203..6271869ad 100644
--- a/lib/rplan.h
+++ b/lib/rplan.h
@@ -83,6 +83,7 @@ struct kr_query {
 	uint32_t secret;
 	uint16_t fails;
 	uint16_t reorder; /**< Seed to reorder (cached) RRs in answer or zero. */
+	struct timeval creation_time;
 	struct timeval timestamp;
 	struct kr_zonecut zone_cut;
 	struct kr_nsrep ns;