From: Olivier Houchard <ohouchard@haproxy.com>
Date: Mon, 8 Jan 2018 15:28:57 +0000 (+0100)
Subject: MINOR: dns: Handle SRV record weight correctly.
X-Git-Tag: v1.9-dev1~523
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=2ec2db9725fb54a76c726c5b8cc502071c575d28;p=thirdparty%2Fhaproxy.git

MINOR: dns: Handle SRV record weight correctly.

A SRV record weight can range from 0 to 65535, while haproxy weight goes
from 0 to 256, so we have to divide it by 256 before handing it to haproxy.
Also, a SRV record with a weight of 0 doesn't mean the server shouldn't be
used, so use a minimum weight of 1.

This should probably be backported to 1.8.
---

diff --git a/include/types/dns.h b/include/types/dns.h
index b1f068a613..9b1d08df7f 100644
--- a/include/types/dns.h
+++ b/include/types/dns.h
@@ -143,7 +143,7 @@ struct dns_answer_item {
 	int16_t         class;                     /* query class */
 	int32_t         ttl;                       /* response TTL */
 	int16_t         priority;                  /* SRV type priority */
-	int16_t         weight;                    /* SRV type weight */
+	uint16_t        weight;                    /* SRV type weight */
 	int16_t         port;                      /* SRV type port */
 	int16_t         data_len;                  /* number of bytes in target below */
 	struct sockaddr address;                   /* IPv4 or IPv6, network format */
diff --git a/src/dns.c b/src/dns.c
index fceef2e480..a957710edb 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -522,10 +522,16 @@ static void dns_check_dns_response(struct dns_resolution *res)
 				if (srv->srvrq == srvrq && srv->svc_port == item->port &&
 				    item->data_len == srv->hostname_dn_len &&
 				    !memcmp(srv->hostname_dn, item->target, item->data_len)) {
-					if (srv->uweight != item->weight) {
+					int ha_weight;
+
+					/* Make sure weight is at least 1, so
+					 * that the server will be used.
+					 */
+					ha_weight = item->weight / 256 + 1;
+					if (srv->uweight != ha_weight) {
 						char weight[9];
 
-						snprintf(weight, sizeof(weight), "%d", item->weight);
+						snprintf(weight, sizeof(weight), "%d", ha_weight);
 						server_parse_weight_change_request(srv, weight);
 					}
 					HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
@@ -547,6 +553,7 @@ static void dns_check_dns_response(struct dns_resolution *res)
 			if (srv) {
 				const char *msg = NULL;
 				char weight[9];
+				int ha_weight;
 				char hostname[DNS_MAX_NAME_SIZE];
 
 				if (dns_dn_label_to_str(item->target, item->data_len+1,
@@ -563,7 +570,13 @@ static void dns_check_dns_response(struct dns_resolution *res)
 				if ((srv->check.state & CHK_ST_CONFIGURED) &&
 				    !(srv->flags & SRV_F_CHECKPORT))
 					srv->check.port = item->port;
-				snprintf(weight, sizeof(weight), "%d", item->weight);
+
+				/* Make sure weight is at least 1, so
+				 * that the server will be used.
+				 */
+				ha_weight = item->weight / 256 + 1;
+
+				snprintf(weight, sizeof(weight), "%d", ha_weight);
 				server_parse_weight_change_request(srv, weight);
 				HA_SPIN_UNLOCK(SERVER_LOCK, &srv->lock);
 			}