Merge pull request #18334 from FRRouting/mergify/bp/stable/10.1/pr-18315

pimd: Fix PIM6 MLD VRF support (use recvmsg() pktinfo) (backport #18315)

1 files changed, 15 insertions, 12 deletions

diff --git a/pimd/pim6_mld.c b/pimd/pim6_mld.c
index a39d182990..e258a52dc5 100644
--- a/pimd/pim6_mld.c
+++ b/pimd/pim6_mld.c
@@ -1665,18 +1665,6 @@ static void gm_t_recv(struct event *t)
 		goto out_free;
 	}
 
-	struct interface *ifp;
-
-	ifp = if_lookup_by_index(pkt_src->sin6_scope_id, pim->vrf->vrf_id);
-	if (!ifp || !ifp->info)
-		goto out_free;
-
-	struct pim_interface *pim_ifp = ifp->info;
-	struct gm_if *gm_ifp = pim_ifp->mld;
-
-	if (!gm_ifp)
-		goto out_free;
-
 	for (cmsg = CMSG_FIRSTHDR(mh); cmsg; cmsg = CMSG_NXTHDR(mh, cmsg)) {
 		if (cmsg->cmsg_level != SOL_IPV6)
 			continue;
@@ -1695,6 +1683,21 @@ static void gm_t_recv(struct event *t)
 		}
 	}
 
+	/* Prefer pktinfo as that also works in case of VRF */
+	ifindex_t ifindex = pktinfo ? pktinfo->ipi6_ifindex
+	                            : pkt_src->sin6_scope_id;
+	struct interface *ifp;
+
+	ifp = if_lookup_by_index(ifindex, pim->vrf->vrf_id);
+	if (!ifp || !ifp->info)
+		goto out_free;
+
+	struct pim_interface *pim_ifp = ifp->info;
+	struct gm_if *gm_ifp = pim_ifp->mld;
+
+	if (!gm_ifp)
+		goto out_free;
+
 	if (!pktinfo || !hoplimit) {
 		zlog_err(log_ifp(
 			"BUG: packet without IPV6_PKTINFO or IPV6_HOPLIMIT"));