From: Michał Kępień <michal@isc.org>
Date: Tue, 8 Jan 2019 10:17:39 +0000 (+0100)
Subject: Refactor code sending a query to the next server upon a timeout
X-Git-Tag: v9.13.6~71^2~2
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=c108fc5c6e318184f32dae306baa57ef3ad545c0;p=thirdparty%2Fbind9.git

Refactor code sending a query to the next server upon a timeout

When a query times out and another server is available for querying
within the same lookup, the timeout handler - connect_timeout() - is
responsible for sending the query to the next server.  Extract the
relevant part of connect_timeout() to a separate function in order to
improve code readability.
---

diff --git a/bin/dig/dighost.c b/bin/dig/dighost.c
index 400fcaf34fe..2f980ab4744 100644
--- a/bin/dig/dighost.c
+++ b/bin/dig/dighost.c
@@ -2880,6 +2880,36 @@ send_udp(dig_query_t *query) {
 	sendcount++;
 }
 
+/*%
+ * If there are more servers available for querying within 'lookup', initiate a
+ * TCP or UDP query to the next available server and return true; otherwise,
+ * return false.
+ */
+static bool
+try_next_server(dig_lookup_t *lookup) {
+	dig_query_t *current_query, *next_query;
+
+	current_query = lookup->current_query;
+	if (current_query == NULL || !ISC_LINK_LINKED(current_query, link)) {
+		return (false);
+	}
+
+	next_query = ISC_LIST_NEXT(current_query, link);
+	if (next_query == NULL) {
+		return (false);
+	}
+
+	debug("trying next server...");
+
+	if (lookup->tcp_mode) {
+		send_tcp_connect(next_query);
+	} else {
+		send_udp(next_query);
+	}
+
+	return (true);
+}
+
 /*%
  * IO timeout handler, used for both connect and recv timeouts.  If
  * retries are still allowed, either resend the UDP packet or queue a
@@ -2888,7 +2918,7 @@ send_udp(dig_query_t *query) {
 static void
 connect_timeout(isc_task_t *task, isc_event_t *event) {
 	dig_lookup_t *l = NULL;
-	dig_query_t *query = NULL, *cq;
+	dig_query_t *query = NULL;
 
 	UNUSED(task);
 	REQUIRE(event->ev_type == ISC_TIMEREVENT_IDLE);
@@ -2908,18 +2938,12 @@ connect_timeout(isc_task_t *task, isc_event_t *event) {
 		return;
 	}
 
-	if ((query != NULL) && (query->lookup->current_query != NULL) &&
-	    ISC_LINK_LINKED(query->lookup->current_query, link) &&
-	    (ISC_LIST_NEXT(query->lookup->current_query, link) != NULL)) {
-		debug("trying next server...");
-		cq = query->lookup->current_query;
-		if (!l->tcp_mode)
-			send_udp(ISC_LIST_NEXT(cq, link));
-		else {
-			if (query->sock != NULL)
+	if (try_next_server(l)) {
+		if (l->tcp_mode) {
+			if (query->sock != NULL) {
 				isc_socket_cancel(query->sock, NULL,
 						  ISC_SOCKCANCEL_ALL);
-			send_tcp_connect(ISC_LIST_NEXT(cq, link));
+			}
 		}
 		UNLOCK_LOOKUP;
 		return;