From: Christopher Faulet <cfaulet@haproxy.com>
Date: Wed, 10 Mar 2021 14:07:27 +0000 (+0100)
Subject: BUG/MINOR; resolvers: Ignore DNS resolution for expired SRV item
X-Git-Tag: v2.4-dev12~25
X-Git-Url: http://git.haproxy.org/?a=commitdiff_plain;h=49531e8471a1c1ae9e1c7a6c1aeeb00713024beb;p=haproxy-2.5.git

BUG/MINOR; resolvers: Ignore DNS resolution for expired SRV item

If no ADD item is found for a SRV item in a SRV response, a DNS resolution
is triggered. When it succeeds, we must be sure the SRV item is still
alive. Otherwise the DNS resolution must be ignored.

This patch depends on the commit "MINOR: resolvers: Move last_seen time of
an ADD into its corresponding SRV item". Both must be backported as far as
2.2.
---

diff --git a/src/server.c b/src/server.c
index f1ba3cf..3b4d41e 100644
--- a/src/server.c
+++ b/src/server.c
@@ -3126,7 +3126,25 @@ int snr_resolution_cb(struct resolv_requester *requester, struct dns_counters *c
 	if (!s)
 		return 1;
 
+	if (s->srvrq) {
+		struct resolv_answer_item *srv_item;
+
+		/* If DNS resolution is disabled ignore it. */
+		if (s->flags & SRV_F_NO_RESOLUTION)
+			return 1;
+
+		/* The server is based on a SRV record, thus, find the
+		 * associated answer record. If not found, it means the SRV item
+		 * has expired and this resolution must be ignored.
+		 */
+		srv_item = find_srvrq_answer_record(requester);
+		if (!srv_item)
+			return 1;
+	}
+
 	resolution = s->resolv_requester->resolution;
+	if (!resolution)
+		return 1;
 
 	/* initializing variables */
 	firstip = NULL;		/* pointer to the first valid response found */
@@ -3191,6 +3209,7 @@ int snr_resolution_cb(struct resolv_requester *requester, struct dns_counters *c
 	srv_update_addr(s, firstip, firstip_sin_family, (char *) chk->area);
 
  update_status:
+
 	snr_update_srv_status(s, has_no_ip);
 	return 1;