BUG/MINOR: dns: trigger a DNS query type change on resolution timeout
After Cedric Jeanneret reported an issue with HAProxy and DNS resolution
when multiple servers are in use, I saw that the implementation of DNS
query type update on resolution timeout was not implemented, even if it
is documented.
backport: 1.6 and above
diff --git a/src/dns.c b/src/dns.c
index 97f9f0a..4603e21 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -1164,6 +1164,7 @@
{
struct dns_resolvers *resolvers = t->context;
struct dns_resolution *resolution, *res_back;
+ int res_preferred_afinet, res_preferred_afinet6;
/* timeout occurs inevitably for the first element of the FIFO queue */
if (LIST_ISEMPTY(&resolvers->curr_resolution)) {
@@ -1193,6 +1194,19 @@
resolution->try -= 1;
+ res_preferred_afinet = resolution->resolver_family_priority == AF_INET && resolution->query_type == DNS_RTYPE_A;
+ res_preferred_afinet6 = resolution->resolver_family_priority == AF_INET6 && resolution->query_type == DNS_RTYPE_AAAA;
+
+ /* let's change the query type if needed */
+ if (res_preferred_afinet6) {
+ /* fallback from AAAA to A */
+ resolution->query_type = DNS_RTYPE_A;
+ }
+ else if (res_preferred_afinet) {
+ /* fallback from A to AAAA */
+ resolution->query_type = DNS_RTYPE_AAAA;
+ }
+
/* resend the DNS query */
dns_send_query(resolution);