From: Vincent Bernat <vincent@bernat.ch>
Date: Mon, 23 Sep 2019 19:35:14 +0000 (+0200)
Subject: netlink: ignore IFLA_LINK if we previously received IFLA_LINK_NETNSID
X-Git-Tag: 1.0.5~43
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=5a85fbc934334c629a0d4cce5a8983e442f5a0df;p=thirdparty%2Flldpd.git

netlink: ignore IFLA_LINK if we previously received IFLA_LINK_NETNSID

Starting from 5.2 (commit feadc4b6cf42), IFLA_LINK appear after
IFLA_LINK_NETNSID. Handle this case correctly.
---

diff --git a/src/daemon/netlink.c b/src/daemon/netlink.c
index c89e1490..c2136877 100644
--- a/src/daemon/netlink.c
+++ b/src/daemon/netlink.c
@@ -283,13 +283,18 @@ netlink_parse_link(struct nlmsghdr *msg,
 			break;
 		case IFLA_LINK:
 			/* Index of "lower" interface */
-			iff->lower_idx = *(int*)RTA_DATA(attribute);
-			log_debug("netlink", "attribute IFLA_LINK for %s: %d",
-			    iff->name ? iff->name : "(unknown)", iff->lower_idx);
+			if (iff->lower_idx == -1) {
+				iff->lower_idx = *(int*)RTA_DATA(attribute);
+				log_debug("netlink", "attribute IFLA_LINK for %s: %d",
+				    iff->name ? iff->name : "(unknown)", iff->lower_idx);
+			} else {
+				log_debug("netlink", "attribute IFLA_LINK for %s: %d (ignored)",
+				    iff->name ? iff->name : "(unknown)", iff->lower_idx);
+			}
 			break;
 		case IFLA_LINK_NETNSID:
 			/* Is the lower interface into another namesapce? */
-			iff->lower_idx = -1;
+			iff->lower_idx = -2;
 			log_debug("netlink", "attribute IFLA_LINK_NETNSID received for %s",
 			    iff->name ? iff->name : "(unknown)");
 			break;
@@ -321,6 +326,8 @@ netlink_parse_link(struct nlmsghdr *msg,
 		 * and we don't want to miss it. */
 		iff->flags &= ~IFF_SLAVE;
 	}
+	if (iff->lower_idx == -2)
+		iff->lower_idx = -1;
 
 	if (ifi->ifi_family == AF_BRIDGE && msg->nlmsg_type == RTM_DELLINK && iff->upper_idx != -1) {
 		log_debug("netlink", "removal of %s from bridge %d",
@@ -688,8 +695,11 @@ end:
 						if (iface2->lower_idx == iface1->index) {
 							iface1->lower = NULL;
 							log_debug("netlink",
-							    "link loop detected between %s and %s",
-							    iface1->name, iface2->name);
+							    "link loop detected between %s(%d) and %s(%d)",
+							    iface1->name,
+							    iface1->index,
+							    iface2->name,
+							    iface2->index);
 						} else {
 							log_debug("netlink",
 							    "lower interface for %s is %s",