svn commit: r225495 - stable/8/sys/net

[Andrew Thompson]

Author: thompsa
Date: Sun Sep 11 23:37:40 2011
New Revision: 225495
URL: http://svn.freebsd.org/changeset/base/225495

Log:
  MFC r225380
  
   On the first loop for generating a bridge MAC address use the local
   hostid, this gives a good chance of keeping the same address over
   reboots. This is intended to help IPV6 and similar which generate
   their addresses from the mac.
  
  PR:		kern/160300
  Submitted by:	mdodd

Modified:
  stable/8/sys/net/if_bridge.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)

Modified: stable/8/sys/net/if_bridge.c
==============================================================================
--- stable/8/sys/net/if_bridge.c	Sun Sep 11 21:38:33 2011	(r225494)
+++ stable/8/sys/net/if_bridge.c	Sun Sep 11 23:37:40 2011	(r225495)
@@ -85,6 +85,7 @@ __FBSDID("$FreeBSD$");
 #include <sys/malloc.h>
 #include <sys/protosw.h>
 #include <sys/systm.h>
+#include <sys/jail.h>
 #include <sys/time.h>
 #include <sys/socket.h> /* for net/if.h */
 #include <sys/sockio.h>
@@ -560,7 +561,8 @@ bridge_clone_create(struct if_clone *ifc
 {
 	struct bridge_softc *sc, *sc2;
 	struct ifnet *bifp, *ifp;
-	int retry;
+	int fb, retry;
+	unsigned long hostid;
 
 	sc = malloc(sizeof(*sc), M_DEVBUF, M_WAITOK|M_ZERO);
 	ifp = sc->sc_ifp = if_alloc(IFT_ETHER);
@@ -593,17 +595,30 @@ bridge_clone_create(struct if_clone *ifc
 	IFQ_SET_READY(&ifp->if_snd);
 
 	/*
-	 * Generate a random ethernet address with a locally administered
-	 * address.
+	 * Generate an ethernet address with a locally administered address.
 	 *
 	 * Since we are using random ethernet addresses for the bridge, it is
 	 * possible that we might have address collisions, so make sure that
 	 * this hardware address isn't already in use on another bridge.
+	 * The first try uses the hostid and falls back to arc4rand().
 	 */
+	fb = 0;
+	getcredhostid(curthread->td_ucred, &hostid);
 	for (retry = 1; retry != 0;) {
-		arc4rand(sc->sc_defaddr, ETHER_ADDR_LEN, 1);
-		sc->sc_defaddr[0] &= ~1;	/* clear multicast bit */
-		sc->sc_defaddr[0] |= 2;		/* set the LAA bit */
+		if (fb || hostid == 0) {
+			arc4rand(sc->sc_defaddr, ETHER_ADDR_LEN, 1);
+			sc->sc_defaddr[0] &= ~1;/* clear multicast bit */
+			sc->sc_defaddr[0] |= 2;	/* set the LAA bit */
+		} else {
+			sc->sc_defaddr[0] = 0x2;
+			sc->sc_defaddr[1] = (hostid >> 24) & 0xff;
+			sc->sc_defaddr[2] = (hostid >> 16) & 0xff;
+			sc->sc_defaddr[3] = (hostid >> 8 ) & 0xff;
+			sc->sc_defaddr[4] =  hostid        & 0xff;
+			sc->sc_defaddr[5] = ifp->if_dunit & 0xff;
+		}
+
+		fb = 1;
 		retry = 0;
 		mtx_lock(&bridge_list_mtx);
 		LIST_FOREACH(sc2, &bridge_list, sc_list) {