we used to use the lowest (so it is deterministic) mac address in the

system for the bridge ID for stp. That worksfine unless you have
two bridges in the system that talkto the same neighboring systems
(switches), because the two bridges on the openbsd system would have the
same ID.
fix by only looking at interfaces part of the bridge and using the lowest
mac address of these. works fine because stpcan only be enabled on
IFT_ETHER interfaces so there is always at least one and we re-evaluate
every time an interface is added or deleted from the bridge.
diff was rotting in my tree for at least a year, I have no idea what
triggered it really.
ok reyk mk djm

1 files changed, 10 insertions, 12 deletions

diff --git a/sys/net/bridgestp.c b/sys/net/bridgestp.c
index 7d0f11b8fb5..e05e1be468a 100644
--- a/sys/net/bridgestp.c
+++ b/sys/net/bridgestp.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: bridgestp.c,v 1.32 2008/05/21 21:10:50 mk Exp $	*/
+/*	$OpenBSD: bridgestp.c,v 1.33 2008/06/13 19:08:19 henning Exp $	*/
 
 /*
  * Copyright (c) 2000 Jason L. Wright (jason@thought.net)
@@ -1871,7 +1871,7 @@ void
 bstp_initialization(struct bstp_state *bs)
 {
 	struct bstp_port *bp;
-	struct ifnet *ifp, *mif;
+	struct ifnet *mif = NULL;
 	u_char *e_addr;
 
 	if (LIST_EMPTY(&bs->bs_bplist)) {
@@ -1879,25 +1879,23 @@ bstp_initialization(struct bstp_state *bs)
 		return;
 	}
 
-	mif = NULL;
 	/*
 	 * Search through the Ethernet interfaces and find the one
-	 * with the lowest value. The adapter which we take the MAC
-	 * address from does not need to be part of the bridge, it just
-	 * needs to be a unique value. It is not possible for mif to be
+	 * with the lowest value.
+	 * Make sure we take the address from an interface that is
+	 * part of the bridge to make sure two bridges on the system
+	 * will not use the same one. It is not possible for mif to be
 	 * null, at this point we have at least one STP port and hence
 	 * at least one NIC.
 	 */
-	TAILQ_FOREACH(ifp, &ifnet, if_list) {
-		if (ifp->if_type != IFT_ETHER)
-			continue;
+	LIST_FOREACH(bp, &bs->bs_bplist, bp_next) {
 		if (mif == NULL) {
-			mif = ifp;
+			mif = bp->bp_ifp;
 			continue;
 		}
-		if (bstp_addr_cmp(LLADDR(ifp->if_sadl),
+		if (bstp_addr_cmp(LLADDR(bp->bp_ifp->if_sadl),
 		    LLADDR(mif->if_sadl)) < 0) {
-			mif = ifp;
+			mif = bp->bp_ifp;
 			continue;
 		}
 	}