[issue664] Second patch for CARP

Baptiste Ritter baptiste.ritter at ulp.u-strasbg.fr
Sat Aug 11 12:33:25 PDT 2007


Thomas Nikolajsen a écrit :
> Please update carp(4) SYNOPSIS to:
> options CARP
> pseudo-device carp
> (not 'device carp').

Done ; the new patch is attached.

Thanks Thomas for keeping a close watch to the patch.

Cheers,

-- 
Baptiste Ritter
diff --git a/etc/protocols b/etc/protocols
index 4399da5..fc04f48 100644
--- a/etc/protocols
+++ b/etc/protocols
@@ -120,7 +120,7 @@ ipcomp	108	IPComp		# IP Payload Compress
 snp	109	SNP		# Sitara Networks Protocol
 compaq-peer	110	Compaq-Peer	# Compaq Peer Protocol
 ipx-in-ip	111	IPX-in-IP	# IPX in IP
-vrrp	112	VRRP		# Virtual Router Redundancy Protocol
+carp	112	CARP	vrrp		# Common Address Redundancy Protocol
 pgm	113	PGM		# PGM Reliable Transport Protocol
 #	114			# any 0-hop protocol
 l2tp	115	L2TP		# Layer Two Tunneling Protocol
diff --git a/sbin/ifconfig/Makefile b/sbin/ifconfig/Makefile
index c6556e6..f15aaa7 100644
--- a/sbin/ifconfig/Makefile
+++ b/sbin/ifconfig/Makefile
@@ -24,7 +24,7 @@ SRCS+=	ifmedia.c		# SIOC[GS]IFMEDIA supp
 SRCS+=	ifvlan.c		# SIOC[GS]ETVLAN support
 SRCS+=	ifieee80211.c		# SIOC[GS]IEEE80211 support
 
-#SRCS+=	ifcarp.c		# SIOC[GS]VH support
+SRCS+=	ifcarp.c		# SIOC[GS]VH support
 #SRCS+=	ifpfsync.c		# pfsync(4) support
 
 SRCS+=	ifbridge.c		# bridge support
diff --git a/sbin/ifconfig/ifcarp.c b/sbin/ifconfig/ifcarp.c
new file mode 100644
index 0000000..2ab73f3
--- /dev/null
+++ b/sbin/ifconfig/ifcarp.c
@@ -0,0 +1,200 @@
+/*	$Id$	*/
+/*	from $FreeBSD: src/sbin/ifconfig/ifcarp.c,v 1.2 2005/02/22 14:07:47 glebius Exp $ */
+/*	from $OpenBSD: ifconfig.c,v 1.82 2003/10/19 05:43:35 mcbride Exp $ */
+
+/*
+ * Copyright (c) 2002 Michael Shalayeff. All rights reserved.
+ * Copyright (c) 2003 Ryan McBride. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/param.h>
+#include <sys/ioctl.h>
+#include <sys/socket.h>
+#include <sys/sockio.h>
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#include <net/ethernet.h>
+#include <net/if.h>
+#include <netinet/ip_carp.h>
+#include <net/route.h>
+
+#include <ctype.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <err.h>
+#include <errno.h>
+
+#include "ifconfig.h"
+
+static const char *carp_states[] = { CARP_STATES };
+
+void carp_status(int s);
+void setcarp_advbase(const char *,int, int, const struct afswtch *rafp);
+void setcarp_advskew(const char *, int, int, const struct afswtch *rafp);
+void setcarp_passwd(const char *, int, int, const struct afswtch *rafp);
+void setcarp_vhid(const char *, int, int, const struct afswtch *rafp);
+
+void
+carp_status(int s)
+{
+	const char *state;
+	struct carpreq carpr;
+
+	memset((char *)&carpr, 0, sizeof(struct carpreq));
+	ifr.ifr_data = (caddr_t)&carpr;
+
+	if (ioctl(s, SIOCGVH, (caddr_t)&ifr) == -1)
+		return;
+
+	if (carpr.carpr_vhid > 0) {
+		if (carpr.carpr_state > CARP_MAXSTATE)
+			state = "<UNKNOWN>";
+		else
+			state = carp_states[carpr.carpr_state];
+
+		printf("\tcarp: %s vhid %d advbase %d advskew %d\n",
+		    state, carpr.carpr_vhid, carpr.carpr_advbase,
+		    carpr.carpr_advskew);
+	}
+
+	return;
+
+}
+
+void
+setcarp_passwd(const char *val, int d, int s, const struct afswtch *afp)
+{
+	struct carpreq carpr;
+
+	memset((char *)&carpr, 0, sizeof(struct carpreq));
+	ifr.ifr_data = (caddr_t)&carpr;
+
+	if (ioctl(s, SIOCGVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCGVH");
+
+	/* XXX Should hash the password into the key here, perhaps? */
+	strlcpy(carpr.carpr_key, val, CARP_KEY_LEN);
+
+	if (ioctl(s, SIOCSVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCSVH");
+
+	return;
+}
+
+void
+setcarp_vhid(const char *val, int d, int s, const struct afswtch *afp)
+{
+	int vhid;
+	struct carpreq carpr;
+
+	vhid = atoi(val);
+
+	if (vhid <= 0)
+		errx(1, "vhid must be greater than 0");
+
+	memset((char *)&carpr, 0, sizeof(struct carpreq));
+	ifr.ifr_data = (caddr_t)&carpr;
+
+	if (ioctl(s, SIOCGVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCGVH");
+
+	carpr.carpr_vhid = vhid;
+
+	if (ioctl(s, SIOCSVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCSVH");
+
+	return;
+}
+
+void
+setcarp_advskew(const char *val, int d, int s, const struct afswtch *afp)
+{
+	int advskew;
+	struct carpreq carpr;
+
+	advskew = atoi(val);
+
+	memset((char *)&carpr, 0, sizeof(struct carpreq));
+	ifr.ifr_data = (caddr_t)&carpr;
+
+	if (ioctl(s, SIOCGVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCGVH");
+
+	carpr.carpr_advskew = advskew;
+
+	if (ioctl(s, SIOCSVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCSVH");
+
+	return;
+}
+
+void
+setcarp_advbase(const char *val, int d, int s, const struct afswtch *afp)
+{
+	int advbase;
+	struct carpreq carpr;
+
+	advbase = atoi(val);
+
+	memset((char *)&carpr, 0, sizeof(struct carpreq));
+	ifr.ifr_data = (caddr_t)&carpr;
+
+	if (ioctl(s, SIOCGVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCGVH");
+
+	carpr.carpr_advbase = advbase;
+
+	if (ioctl(s, SIOCSVH, (caddr_t)&ifr) == -1)
+		err(1, "SIOCSVH");
+
+	return;
+}
+
+static struct cmd carp_cmds[] = {
+	DEF_CMD_ARG("advbase",	setcarp_advbase),
+	DEF_CMD_ARG("advskew",	setcarp_advskew),
+	DEF_CMD_ARG("pass",	setcarp_passwd),
+	DEF_CMD_ARG("vhid",	setcarp_vhid),
+};
+static struct afswtch af_carp = {
+	.af_name	= "af_carp",
+	.af_af		= AF_UNSPEC,
+	.af_other_status = carp_status,
+};
+
+static __constructor void
+carp_ctor(void)
+{
+#define	N(a)	(sizeof(a) / sizeof(a[0]))
+	int i;
+
+	for (i = 0; i < N(carp_cmds);  i++)
+		cmd_register(&carp_cmds[i]);
+	af_register(&af_carp);
+#undef N
+}
diff --git a/sbin/ifconfig/ifconfig.8 b/sbin/ifconfig/ifconfig.8
index c832cc1..e9820fb 100644
--- a/sbin/ifconfig/ifconfig.8
+++ b/sbin/ifconfig/ifconfig.8
@@ -28,8 +28,9 @@
 .\"     From: @(#)ifconfig.8	8.3 (Berkeley) 1/5/94
 .\" $FreeBSD: src/sbin/ifconfig/ifconfig.8,v 1.124 2006/10/10 09:44:08 ru Exp $
 .\" $DragonFly: src/sbin/ifconfig/ifconfig.8,v 1.19 2007/04/09 21:20:37 swildner Exp $
+
 .\"
-.Dd November 19, 2006
+.Dd April 8, 2007
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -1388,6 +1389,31 @@ The
 argument is useless and hence deprecated.
 .El
 .Pp
+The following parameters are specific to
+.Xr carp 4
+interfaces:
+.Bl -tag -width indent
+.It Cm advbase Ar seconds
+Specifies the base of the advertisement interval in seconds.
+The acceptable values are 1 to 255.
+The default value is 1.
+.\" The default value is
+.\" .Dv CARP_DFLTINTV .
+.It Cm advskew Ar interval
+Specifies the skew to add to the base advertisement interval to
+make one host advertise slower than another host.
+It is specified in 1/256 of seconds.
+The acceptable values are 1 to 254.
+The default value is 0.
+.It Cm pass Ar phrase
+Set the authentication key to
+.Ar phrase .
+.It Cm vhid Ar n
+Set the virtual host ID.
+This is a required setting.
+Acceptable values are 1 to 255.
+.El
+.Pp
 The
 .Nm
 utility displays the current configuration for a network interface
@@ -1460,6 +1486,7 @@ requested address is unknown, or the use
 tried to alter an interface's configuration.
 .Sh SEE ALSO
 .Xr netstat 1 ,
+.Xr carp 4 ,
 .Xr ifmedia 4 ,
 .Xr netintro 4 ,
 .Xr polling 4 ,
diff --git a/sbin/ifconfig/ifmedia.c b/sbin/ifconfig/ifmedia.c
index 978c79a..7876715 100644
--- a/sbin/ifconfig/ifmedia.c
+++ b/sbin/ifconfig/ifmedia.c
@@ -175,6 +175,12 @@ media_status(int s)
 			else
 				printf("no carrier");
 			break;
+		case IFM_CARP:
+			if (ifmr.ifm_status & IFM_ACTIVE)
+				printf("master");
+			else
+				printf("backup");
+			break;
 		}
 		putchar('\n');
 	}
diff --git a/share/man/man4/Makefile b/share/man/man4/Makefile
index 4b9fcba..53cf3c8 100644
--- a/share/man/man4/Makefile
+++ b/share/man/man4/Makefile
@@ -34,6 +34,7 @@ MAN=	aac.4 \
 	bridge.4 \
 	bt.4 \
 	cardbus.4 \
+	carp.4 \
 	ccd.4 \
 	cd.4 \
 	ch.4 \
diff --git a/share/man/man4/carp.4 b/share/man/man4/carp.4
new file mode 100644
index 0000000..1a458a8
--- /dev/null
+++ b/share/man/man4/carp.4
@@ -0,0 +1,263 @@
+.\"	$OpenBSD: carp.4,v 1.16 2004/12/07 23:41:35 jmc Exp $
+.\"     $FreeBSD: src/share/man/man4/carp.4,v 1.10 2006/06/07 10:26:51 glebius Exp $
+.\"	$Id$
+.\"
+.\" Copyright (c) 2003, Ryan McBride.  All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\"
+.Dd April 9, 2007
+.Dt CARP 4
+.Os
+.Sh NAME
+.Nm carp
+.Nd Common Address Redundancy Protocol
+.Sh SYNOPSIS
+.Cd "pseudo-device carp"
+.Sh DESCRIPTION
+The
+.Nm
+interface is a pseudo-device that implements and controls the
+CARP protocol.
+CARP allows multiple hosts on the same local network to share a set of IP addresses.
+Its primary purpose is to ensure that these
+addresses are always available, but in some configurations
+.Nm
+can also provide load balancing functionality.
+.Pp
+A
+.Nm
+interface can be created at runtime using the
+.Nm ifconfig Li carp Ns Ar N Cm create
+command or by configuring
+it via
+.Va cloned_interfaces
+in the
+.Pa /etc/rc.conf
+file.
+.Pp
+To use
+.Nm ,
+the administrator needs to configure at minimum a common virtual host ID (VHID)
+and virtual host IP address on each machine which is to take part in the virtual
+group.
+Additional parameters can also be set on a per-interface basis:
+.Cm advbase
+and
+.Cm advskew ,
+which are used to control how frequently the host sends advertisements when it
+is the master for a virtual host, and
+.Cm pass
+which is used to authenticate
+.Nm
+advertisements.
+The
+.Cm advbase
+parameter stands for
+.Dq "advertisement base" .
+It is measured in seconds and specifies the base of the advertisement interval.
+The
+.Cm advskew
+parameter stands for
+.Dq "advertisement skew" .
+It is measured in 1/256 of seconds.
+It is added to the base advertisement interval to make one host advertise
+a bit slower that the other does.
+Both
+.Cm advbase
+and
+.Cm advskew
+are put inside CARP advertisements.
+These configurations can be done using
+.Xr ifconfig 8 ,
+or through the
+.Dv SIOCSVH
+.Xr ioctl 2 .
+.Pp
+Additionally, there are a number of global parameters which can be set using
+.Xr sysctl 8 :
+.Bl -tag -width ".Va net.inet.carp.arpbalance"
+.It Va net.inet.carp.allow
+Accept incoming
+.Nm
+packets.
+Enabled by default.
+.It Va net.inet.carp.preempt
+Allow virtual hosts to preempt each other.
+It is also used to failover
+.Nm
+interfaces as a group.
+When the option is enabled and one of the
+.Nm
+enabled physical interfaces
+goes down,
+.Cm advskew
+is changed to 240 on all
+.Nm
+interfaces.
+See also the first example.
+Disabled by default.
+.It Va net.inet.carp.log
+Value of 0 disables any logging.
+Value of 1 enables logging of bad
+.Nm
+packets.
+Values above 1 enable logging state changes of
+.Nm
+interfaces.
+Default value is 1.
+.It Va net.inet.carp.arpbalance
+Balance local traffic using ARP (see below).
+Disabled by default.
+.It Va net.inet.carp.suppress_preempt
+A read only value showing the status of preemption suppression.
+Preemption can be suppressed if link on an interface is down
+or when
+.Xr pfsync 4
+interface is not synchronized.
+Value of 0 means that preemption is not suppressed, since no
+problems are detected.
+Every problem increments suppression counter.
+.El
+.Sh ARP level load balancing
+The
+.Nm
+has limited abilities for load balancing the incoming connections
+between hosts in Ethernet network.
+For load balancing operation, one needs several CARP interfaces that
+are configured to the same IP address, but to a different VHIDs.
+Once an ARP request is received, the CARP protocol will use a hashing
+function against the source IP address in the ARP request to determine
+which VHID should this request belong to.
+If the corresponding CARP interface is in master state, the ARP request
+will be replied, otherwise it will be ignored.
+See the
+.Sx EXAMPLES
+section for a practical example of load balancing.
+.Pp
+The ARP load balancing has some limitations.
+First, ARP balancing only works on the local network segment.
+It cannot balance traffic that crosses a router, because the
+router itself will always be balanced to the same virtual host.
+Second, ARP load balancing can lead to asymmetric routing
+of incoming and outgoing traffic, and thus combining it with
+.Xr pfsync 4
+is dangerous, because this creates a race condition between
+balanced routers and a host they are serving.
+Imagine an incoming packet creating state on the first router, being
+forwarded to its destination, and destination replying faster
+than the state information is packed and synced with the second router.
+If the reply would be load balanced to second router, it will be
+dropped due to no state.
+.Sh EXAMPLES
+For firewalls and routers with multiple interfaces, it is desirable to
+failover all of the
+.Nm
+interfaces together, when one of the physical interfaces goes down.
+This is achieved by the preempt option.
+Enable it on both host A and B:
+.Pp
+.Dl sysctl net.inet.carp.preempt=1
+.Pp
+Assume that host A is the preferred master and 192.168.1.x/24 is
+configured on one physical interface and 192.168.2.y/24 on another.
+This is the setup for host A:
+.Bd -literal -offset indent
+ifconfig carp0 create
+ifconfig carp0 vhid 1 pass mekmitasdigoat 192.168.1.1/24
+ifconfig carp1 create
+ifconfig carp1 vhid 2 pass mekmitasdigoat 192.168.2.1/24
+.Ed
+.Pp
+The setup for host B is identical, but it has a higher
+.Cm advskew :
+.Bd -literal -offset indent
+ifconfig carp0 create
+ifconfig carp0 vhid 1 advskew 100 pass mekmitasdigoat 192.168.1.1/24
+ifconfig carp1 create
+ifconfig carp1 vhid 2 advskew 100 pass mekmitasdigoat 192.168.2.1/24
+.Ed
+.Pp
+Because of the preempt option, when one of the physical interfaces of
+host A fails,
+.Cm advskew
+is adjusted to 240 on all its
+.Nm
+interfaces.
+This will cause host B to preempt on both interfaces instead of
+just the failed one.
+.Pp
+In order to set up an ARP balanced virtual host, it is necessary to configure
+one virtual host for each physical host which would respond to ARP requests
+and thus handle the traffic.
+In the following example, two virtual hosts are configured on two hosts to
+provide balancing and failover for the IP address 192.168.1.10.
+.Pp
+First the
+.Nm
+interfaces on host A are configured.
+The
+.Cm advskew
+of 100 on the second virtual host means that its advertisements will be sent
+out slightly less frequently.
+.Bd -literal -offset indent
+ifconfig carp0 create
+ifconfig carp0 vhid 1 pass mekmitasdigoat 192.168.1.10/24
+ifconfig carp1 create
+ifconfig carp1 vhid 2 advskew 100 pass mekmitasdigoat 192.168.1.10/24
+.Ed
+.Pp
+The configuration for host B is identical, except the
+.Cm advskew
+is on virtual host 1 rather than virtual host 2.
+.Bd -literal -offset indent
+ifconfig carp0 create
+ifconfig carp0 vhid 1 advskew 100 pass mekmitasdigoat 192.168.1.10/24
+ifconfig carp1 create
+ifconfig carp1 vhid 2 pass mekmitasdigoat 192.168.1.10/24
+.Ed
+.Pp
+Finally, the ARP balancing feature must be enabled on both hosts:
+.Pp
+.Dl sysctl net.inet.carp.arpbalance=1
+.Pp
+When the hosts receive an ARP request for 192.168.1.10, the source IP address
+of the request is used to compute which virtual host should answer the request.
+The host which is master of the selected virtual host will reply to the
+request, the other(s) will ignore it.
+.Pp
+This way, locally connected systems will receive different ARP replies and
+subsequent IP traffic will be balanced among the hosts.
+If one of the hosts fails, the other will take over the virtual MAC address,
+and begin answering ARP requests on its behalf.
+.Sh SEE ALSO
+.Xr inet 4 ,
+.Xr pfsync 4 ,
+.Xr rc.conf 5 ,
+.Xr ifconfig 8 ,
+.Xr sysctl 8
+.Sh HISTORY
+The
+.Nm
+device first appeared in
+.Ox 3.5 .
diff --git a/share/man/man4/pfsync.4 b/share/man/man4/pfsync.4
index 349e56e..f518690 100644
--- a/share/man/man4/pfsync.4
+++ b/share/man/man4/pfsync.4
@@ -24,7 +24,7 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.Dd November 29, 2002
+.Dd April 9, 2007
 .Dt PFSYNC 4
 .Os
 .Sh NAME
@@ -129,8 +129,76 @@ only the necessary information.
 # ifconfig pfsync0 up syncif fxp0 maxupd 64
 # tcpdump -s1500 -evtni pfsync0
 .Ed
+.Sh USING PFSYNC WITH CARP
+.Nm
+and
+.Xr carp 4
+can be used together to provide automatic failover of a pair of firewalls
+configured in parallel.
+One firewall handles all traffic \- if it dies or
+is shut down, the second firewall takes over automatically.
+.Pp
+Both firewalls in this example have three
+.Xr sis 4
+interfaces.
+sis0 is the external interface, on the 10.0.0.0/24 subnet; sis1 is the
+internal interface, on the 192.168.0.0/24 subnet; and sis2 is the
+.Nm
+interface, using the 192.168.254.0/24 subnet.
+A crossover cable connects the two firewalls via their sis2 interfaces.
+On all three interfaces, firewall A uses the .254 address, while firewall B
+uses .253.
+The interfaces are configured as follows (firewall A unless otherwise
+indicated):
+.Pp
+Interfaces configuration in
+.Pa /etc/rc.conf :
+.Bd -literal -offset indent
+network_interfaces="lo0 sis0 sis1 sis2"
+cloned_interfaces="carp0 carp1"
+ifconfig_sis0="10.0.0.254/24"
+ifconfig_sis1="192.168.0.254/24"
+ifconfig_sis2="192.168.254.254/24"
+ifconfig_carp0="vhid 1 pass foo 10.0.0.1/24"
+ifconfig_carp1="vhid 2 pass bar 192.168.0.1/24"
+pfsync_enable="YES"
+pfsync_syncdev="sis2"
+.Ed
+.Pp
+.Xr pf 4
+must also be configured to allow
+.Nm
+and
+.Xr carp 4
+traffic through.
+The following should be added to the top of
+.Pa /etc/pf.conf :
+.Bd -literal -offset indent
+pass quick on { sis2 } proto pfsync
+pass quick on { sis0 sis1 } proto carp keep state
+.Ed
+.Pp
+If it is preferable that one firewall handle the traffic,
+the
+.Ar advskew
+on the backup firewall's
+.Xr carp 4
+interfaces should be set to something higher than
+the primary's.
+For example, if firewall B is the backup, its
+carp1 configuration would look like this:
+.Bd -literal -offset indent
+ifconfig_carp1="vhid 2 pass bar advskew 100 192.168.0.1/24"
+.Ed
+.Pp
+The following must also be added to
+.Pa /etc/sysctl.conf :
+.Bd -literal -offset indent
+net.inet.carp.preempt=1
+.Ed
 .Sh SEE ALSO
 .Xr tcpdump 1 ,
+.Xr carp 4 ,
 .Xr bpf 4 ,
 .Xr inet 4 ,
 .Xr inet6 4 ,
diff --git a/sys/conf/files b/sys/conf/files
index 92cd5b7..5222fe3 100644
--- a/sys/conf/files
+++ b/sys/conf/files
@@ -79,6 +79,7 @@ crypto/des/des_setkey.c			optional ipsec
 crypto/rijndael/rijndael-alg-fst.c	optional ipsec ipsec_esp
 crypto/rijndael/rijndael-api-fst.c	optional ipsec ipsec_esp
 crypto/sha1.c				optional ipsec
+crypto/sha1.c				optional carp
 crypto/sha2/sha2.c			optional ipsec
 ddb/db_access.c				optional ddb
 ddb/db_kld.c				optional ddb
@@ -887,6 +888,7 @@ netinet/in_gif.c		optional gif inet
 netinet/igmp.c			optional inet
 netinet/in.c			optional inet
 netinet/in_cksum.c		optional inet
+netinet/ip_carp.c		optional carp
 netinet/ip_gre.c		optional gre inet
 netinet/ip_id.c			optional inet
 netinet/in_pcb.c		optional inet
diff --git a/sys/conf/options b/sys/conf/options
index 184ec98..bfeaaef 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -264,6 +264,7 @@ BOOTP_COMPAT		opt_bootp.h
 BOOTP_NFSROOT		opt_bootp.h
 BOOTP_NFSV3		opt_bootp.h
 BOOTP_WIRED_TO		opt_bootp.h
+CARP			opt_carp.h
 ETHER_II		opt_ef.h
 ETHER_8023		opt_ef.h
 ETHER_8022		opt_ef.h
diff --git a/sys/config/LINT b/sys/config/LINT
index 58721c7..92bc5ad 100644
--- a/sys/config/LINT
+++ b/sys/config/LINT
@@ -633,6 +633,10 @@ device		pf
 device		pfsync
 device		pflog
 
+#CARP
+pseudo-device carp
+options CARP
+
 # The MBUF_STRESS_TEST option enables options which create
 # various random failures / extreme cases related to mbuf
 # functions.  See the mbuf(9) manpage for a list of available
diff --git a/sys/config/VKERNEL b/sys/config/VKERNEL
index 6f2cfb6..151f2c8 100644
--- a/sys/config/VKERNEL
+++ b/sys/config/VKERNEL
@@ -73,6 +73,8 @@ options 	DDB
 options 	DDB_TRACE
 options 	INVARIANTS
 
+options		CARP
+
 # Floating point support - do not disable.
 device		npx0	at nexus?
 
@@ -87,6 +89,8 @@ pseudo-device	md		# Memory "disks"
 pseudo-device	gif		# IPv6 and IPv4 tunneling
 pseudo-device	faith	1	# IPv6-to-IPv4 relaying (translation)
 
+pseudo-device	carp
+
 # The `bpf' pseudo-device enables the Berkeley Packet Filter.
 # Be aware of the administrative consequences of enabling this!
 pseudo-device	bpf		#Berkeley packet filter
@@ -96,3 +100,4 @@ pseudo-device	bpf		#Berkeley packet filt
 device		vn
 device		vkd
 device		vke
+
diff --git a/sys/net/if_ethersubr.c b/sys/net/if_ethersubr.c
index d08ae24..7ed3ca4 100644
--- a/sys/net/if_ethersubr.c
+++ b/sys/net/if_ethersubr.c
@@ -40,6 +40,7 @@
 #include "opt_inet6.h"
 #include "opt_ipx.h"
 #include "opt_netgraph.h"
+#include "opt_carp.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -71,6 +72,10 @@
 #include <netinet6/nd6.h>
 #endif
 
+#ifdef CARP
+#include <netinet/ip_carp.h>
+#endif
+
 #ifdef IPX
 #include <netproto/ipx/ipx.h>
 #include <netproto/ipx/ipx_if.h>
@@ -346,6 +351,12 @@ ether_output(struct ifnet *ifp, struct m
 		}
 	}
 
+#ifdef CARP
+	if (ifp->if_carp && (error = carp_output(ifp, m, dst, NULL)))
+		goto bad;
+#endif
+ 
+
 	/* Handle ng_ether(4) processing, if any */
 	if (ng_ether_output_p != NULL) {
 		if ((error = (*ng_ether_output_p)(ifp, &m)) != 0)
@@ -654,6 +665,20 @@ ether_demux(struct ifnet *ifp, struct et
 	if (rule)	/* packet is passing the second time */
 		goto post_stats;
 
+#ifdef CARP
+	/*
+         * XXX: Okay, we need to call carp_forus() and - if it is for
+         * us jump over code that does the normal check
+         * "ac_enaddr == ether_dhost". The check sequence is a bit
+         * different from OpenBSD, so we jump over as few code as
+         * possible, to catch _all_ sanity checks. This needs
+         * evaluation, to see if the carp ether_dhost values break any
+         * of these checks!
+         */
+	if (ifp->if_carp && carp_forus(ifp->if_carp, eh->ether_dhost))
+		goto pre_stats;
+#endif
+
 	/*
 	 * Discard packet if upper layers shouldn't see it because
 	 * it was unicast to a different Ethernet address.  If the
@@ -666,6 +691,11 @@ ether_demux(struct ifnet *ifp, struct et
 		m_freem(m);
 		return;
 	}
+
+#ifdef CARP
+pre_stats:
+#endif
+
 	/* Discard packet if interface is not up */
 	if (!(ifp->if_flags & IFF_UP)) {
 		m_freem(m);
diff --git a/sys/net/if_media.h b/sys/net/if_media.h
index cac9959..1dec5f6 100644
--- a/sys/net/if_media.h
+++ b/sys/net/if_media.h
@@ -239,6 +239,11 @@ int	ifmedia_baudrate(int);
 #define IFM_ATM_UNASSIGNED	0x00000400	/* unassigned cells */
 
 /*
+ * CARP Common Address Redundancy Protocol
+ */
+#define IFM_CARP        0x000000c0
+
+/*
  * Shared media sub-types
  */
 #define	IFM_AUTO	0		/* Autoselect best media */
@@ -316,6 +321,7 @@ struct ifmedia_description {
 	{ IFM_TOKEN,		"Token ring" },				\
 	{ IFM_FDDI,		"FDDI" },				\
 	{ IFM_IEEE80211,	"IEEE 802.11 Wireless Ethernet" },	\
+	{ IFM_CARP,		"Common Address Redundancy Protocol" }, \
 	{ 0, NULL },							\
 }
 
diff --git a/sys/net/if_types.h b/sys/net/if_types.h
index d2e6742..4039b0d 100644
--- a/sys/net/if_types.h
+++ b/sys/net/if_types.h
@@ -252,4 +252,5 @@
 #define	IFT_STF		0xf3
 #define	IFT_PFLOG	0xf5		/* Packet filter logging */
 #define	IFT_PFSYNC	0xf6		/* Packet filter state syncing */
+#define	IFT_CARP	0xf8		/* Common Address Redundancy Protocol */
 #endif /* !_NET_IF_TYPES_H_ */
diff --git a/sys/net/if_var.h b/sys/net/if_var.h
index 8dc1e40..1436a72 100644
--- a/sys/net/if_var.h
+++ b/sys/net/if_var.h
@@ -81,6 +81,7 @@ struct	rtentry;
 struct	rt_addrinfo;
 struct	socket;
 struct	ether_header;
+struct	carp_if;
 struct	ucred;
 struct	lwkt_serialize;
 
@@ -178,6 +179,7 @@ struct ifnet {
 	int	if_dunit;		/* unit or IF_DUNIT_NONE */
 	struct	ifaddrhead if_addrhead;	/* linked list of addresses per if */
 	int	if_pcount;		/* number of promiscuous listeners */
+	struct	carp_if *if_carp;	/* carp interface structure */
 	struct	bpf_if *if_bpf;		/* packet filter structure */
 	u_short	if_index;		/* numeric abbreviation for this if  */
 	short	if_timer;		/* time 'til if_watchdog called */
diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c
index b5c3410..1b7fc53 100644
--- a/sys/netinet/if_ether.c
+++ b/sys/netinet/if_ether.c
@@ -74,6 +74,7 @@
  */
 
 #include "opt_inet.h"
+#include "opt_carp.h"
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -102,6 +103,10 @@
 #include <net/if_arc.h>
 #include <net/iso88025.h>
 
+#ifdef CARP
+#include <netinet/ip_carp.h>
+#endif
+
 #define SIN(s) ((struct sockaddr_in *)s)
 #define SDL(s) ((struct sockaddr_dl *)s)
 
@@ -143,6 +148,7 @@ SYSCTL_INT(_net_link_ether_inet, OID_AUT
 SYSCTL_INT(_net_link_ether_inet, OID_AUTO, proxyall, CTLFLAG_RW,
 	   &arp_proxyall, 0, "");
 
+void 		arprequest_acces(struct ifnet *ifp, struct in_addr *sip, struct in_addr *tip,  u_char *enaddr);
 static void	arp_rtrequest (int, struct rtentry *, struct rt_addrinfo *);
 static void	arprequest (struct ifnet *,
 			struct in_addr *, struct in_addr *, u_char *);
@@ -736,6 +742,7 @@ in_arpinput(struct mbuf *m)
 #ifdef SMP
 	struct netmsg_arp_update msg;
 #endif
+	u_int8_t *enaddr = NULL;
 	int op;
 	int req_len;
 
@@ -770,6 +777,19 @@ in_arpinput(struct mbuf *m)
 		if (ifp->if_bridge && ia->ia_ifp && 
 		    ifp->if_bridge == ia->ia_ifp->if_bridge)
 			goto match;
+		
+#ifdef CARP
+	/*
+	 * If the interface does not match, but the recieving interface
+	 * is part of carp, we call carp_iamatch to see if this is a
+	 * request for the virtual host ip.
+	 * XXX: This is really ugly!
+	 */
+        	if (ifp->if_carp != NULL &&
+		    carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr) &&
+		    itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
+                        goto match;
+#endif
 	}
 	LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash) {
 		/* Skip all ia's which don't match */
@@ -801,8 +821,10 @@ in_arpinput(struct mbuf *m)
 	return;
 
 match:
+	if (!enaddr)
+		enaddr = (u_int8_t *)IF_LLADDR(ifp);
 	myaddr = ia->ia_addr.sin_addr;
-	if (!bcmp(ar_sha(ah), IF_LLADDR(ifp), ifp->if_addrlen)) {
+	if (!bcmp(ar_sha(ah), enaddr, ifp->if_addrlen)) {
 		m_freem(m);	/* it's from me, ignore it. */
 		return;
 	}
@@ -839,7 +861,7 @@ reply:
 	if (itaddr.s_addr == myaddr.s_addr) {
 		/* I am the target */
 		memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
-		memcpy(ar_sha(ah), IF_LLADDR(ifp), ah->ar_hln);
+		memcpy(ar_sha(ah), enaddr, ah->ar_hln);
 	} else {
 		struct llinfo_arp *la;
 
@@ -873,7 +895,7 @@ reply:
 				return;
 			}
 			memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
-			memcpy(ar_sha(ah), IF_LLADDR(ifp), ah->ar_hln);
+			memcpy(ar_sha(ah), enaddr, ah->ar_hln);
 #ifdef DEBUG_PROXY
 			kprintf("arp: proxying for %s\n", inet_ntoa(itaddr));
 #endif
@@ -1039,6 +1061,16 @@ arp_ifinit(struct ifnet *ifp, struct ifa
 	ifa->ifa_flags |= RTF_CLONING;
 }
 
+void
+arp_ifinit2(struct ifnet *ifp, struct ifaddr *ifa, u_char *enaddr)
+{
+	if (IA_SIN(ifa)->sin_addr.s_addr != INADDR_ANY)
+		arprequest(ifp, &IA_SIN(ifa)->sin_addr, &IA_SIN(ifa)->sin_addr,
+			   enaddr);
+	ifa->ifa_rtrequest = arp_rtrequest;
+	ifa->ifa_flags |= RTF_CLONING;
+}
+
 static void
 arp_init(void)
 {
diff --git a/sys/netinet/if_ether.h b/sys/netinet/if_ether.h
index 6a2a65a..97dce14 100644
--- a/sys/netinet/if_ether.h
+++ b/sys/netinet/if_ether.h
@@ -124,6 +124,7 @@ extern u_char	ether_ipmulticast_max[ETHE
 int	arpresolve (struct ifnet *, struct rtentry *, struct mbuf *,
 			struct sockaddr *, u_char *);
 void	arp_ifinit (struct ifnet *, struct ifaddr *);
+void	arp_ifinit2 (struct ifnet *, struct ifaddr *, u_char *);
 #endif
 
 #endif
diff --git a/sys/netinet/in.h b/sys/netinet/in.h
index c867488..5cdedfb 100644
--- a/sys/netinet/in.h
+++ b/sys/netinet/in.h
@@ -169,6 +169,7 @@
 #define	IPPROTO_IPCOMP		108		/* payload compression (IPComp) */
 /* 101-254: Partly Unassigned */
 #define	IPPROTO_PIM		103		/* Protocol Independent Mcast */
+#define	IPPROTO_CARP		112		/* CARP */
 #define	IPPROTO_PGM		113		/* PGM */
 #define	IPPROTO_SCTP		132		/* SCTP */
 #define	IPPROTO_PFSYNC		240		/* PFSYNC */
@@ -297,6 +298,7 @@ struct in_addr {
 #define	INADDR_UNSPEC_GROUP	(u_int32_t)0xe0000000	/* 224.0.0.0 */
 #define	INADDR_ALLHOSTS_GROUP	(u_int32_t)0xe0000001	/* 224.0.0.1 */
 #define	INADDR_ALLRTRS_GROUP	(u_int32_t)0xe0000002	/* 224.0.0.2 */
+#define	INADDR_CARP_GROUP       (u_int32_t)0xe0000012   /* 224.0.0.18 */
 #define	INADDR_PFSYNC_GROUP	(u_int32_t)0xe00000f0	/* 224.0.0.240 */
 #define	INADDR_MAX_LOCAL_GROUP	(u_int32_t)0xe00000ff	/* 224.0.0.255 */
 
diff --git a/sys/netinet/in_proto.c b/sys/netinet/in_proto.c
index ab5bfca..5babd61 100644
--- a/sys/netinet/in_proto.c
+++ b/sys/netinet/in_proto.c
@@ -41,6 +41,7 @@
 #include "opt_ipsec.h"
 #include "opt_inet6.h"
 #include "opt_sctp.h"
+#include "opt_carp.h"
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -105,6 +106,10 @@
 
 #include <net/netisr.h>		/* for cpu0_soport */
 
+#ifdef CARP
+#include <netinet/ip_carp.h>
+#endif
+
 extern	struct domain inetdomain;
 static	struct pr_usrreqs nousrreqs;
 
@@ -294,6 +299,16 @@ struct protosw inetsw[] = {
   rip_init,	0,		0,		0,
   &rip_usrreqs
 },
+
+#ifdef CARP
+ { SOCK_RAW,     &inetdomain,    IPPROTO_CARP,   PR_ATOMIC|PR_ADDR,
+  carp_input,   rip_output,       0,      rip_ctloutput,
+  0,
+  0,            0,              0,              0,
+  &rip_usrreqs
+},
+
+#endif
 };
 
 struct domain inetdomain = {
@@ -332,3 +347,6 @@ SYSCTL_NODE(_net_inet, IPPROTO_DIVERT,	d
 #ifdef PIM
 SYSCTL_NODE(_net_inet, IPPROTO_PIM,    pim,    CTLFLAG_RW, 0,  "PIM");
 #endif
+#ifdef CARP
+SYSCTL_NODE(_net_inet, IPPROTO_CARP,    carp,    CTLFLAG_RW, 0,  "CARP");
+#endif
diff --git a/sys/netinet/ip_carp.c b/sys/netinet/ip_carp.c
new file mode 100644
index 0000000..00a40c4
--- /dev/null
+++ b/sys/netinet/ip_carp.c
@@ -0,0 +1,2215 @@
+/*	$Id$	*/
+/* 	from $FreeBSD: src/sys/netinet/ip_carp.c,v 1.48 2007/02/02 09:39:09 glebius Exp $ */
+
+/*
+ * Copyright (c) 2002 Michael Shalayeff. All rights reserved.
+ * Copyright (c) 2003 Ryan McBride. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include "opt_carp.h"
+/*#include "opt_bpf.h"*/
+#include "opt_inet.h"
+#include "opt_inet6.h"
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/conf.h>
+#include <sys/kernel.h>
+#include <machine/limits.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/module.h>
+#include <sys/time.h>
+#include <sys/proc.h>
+#include <sys/sysctl.h>
+#include <sys/syslog.h>
+#include <sys/signalvar.h>
+#include <sys/filio.h>
+#include <sys/sockio.h>
+#include <sys/in_cksum.h>
+#include <sys/socket.h>
+#include <sys/vnode.h>
+
+#include <machine/stdarg.h>
+
+#include <net/bpf.h>
+#include <net/ethernet.h>
+#include <net/iso88025.h>
+#include <net/if.h>
+#include <net/if_dl.h>
+#include <net/if_types.h>
+#include <net/route.h>
+
+#ifdef INET
+#include <netinet/in.h>
+#include <netinet/in_var.h>
+#include <netinet/in_systm.h>
+#include <netinet/ip.h>
+#include <netinet/ip_var.h>
+#include <netinet/if_ether.h>
+#include <netinet/if_fddi.h>
+#endif
+
+#ifdef INET6
+#include <netinet/icmp6.h>
+#include <netinet/ip6.h>
+#include <netinet6/ip6_var.h>
+#include <netinet6/scope6_var.h>
+#include <netinet6/nd6.h>
+#endif
+
+#include <crypto/sha1.h>
+#include <netinet/ip_carp.h>
+#include <sys/lock.h>
+
+#define	CARP_IFNAME	"carp"
+static MALLOC_DEFINE(M_CARP, "CARP", "CARP interfaces");
+static MALLOC_DEFINE(M_IFNET, "IFNET", "IFNET CARP?");
+SYSCTL_DECL(_net_inet_carp);
+
+struct carp_softc {
+	struct ifnet	 	*sc_ifp;	/* Interface clue */
+	struct ifnet		*sc_carpdev;	/* Pointer to parent interface */
+	struct in_ifaddr 	*sc_ia;		/* primary iface address */
+	struct ip_moptions 	 sc_imo;
+#ifdef INET6
+	struct in6_ifaddr 	*sc_ia6;	/* primary iface address v6 */
+	struct ip6_moptions 	 sc_im6o;
+#endif /* INET6 */
+	TAILQ_ENTRY(carp_softc)	 sc_list;
+
+	enum { INIT = 0, BACKUP, MASTER }	sc_state;
+
+	int			 sc_flags_backup;
+	int			 sc_suppress;
+
+	int			 sc_sendad_errors;
+#define	CARP_SENDAD_MAX_ERRORS	3
+	int			 sc_sendad_success;
+#define	CARP_SENDAD_MIN_SUCCESS 3
+
+	int			 sc_vhid;
+	int			 sc_advskew;
+	int			 sc_naddrs;
+	int			 sc_naddrs6;
+	int			 sc_advbase;	/* seconds */
+	int			 sc_init_counter;
+	u_int64_t		 sc_counter;
+
+	/* authentication */
+#define CARP_HMAC_PAD	64
+	unsigned char sc_key[CARP_KEY_LEN];
+	unsigned char sc_pad[CARP_HMAC_PAD];
+	SHA1_CTX sc_sha1;
+
+	struct callout		 sc_ad_tmo;	/* advertisement timeout */
+	struct callout		 sc_md_tmo;	/* master down timeout */
+	struct callout 		 sc_md6_tmo;	/* master down timeout */
+	
+	LIST_ENTRY(carp_softc)	 sc_next;	/* Interface clue */
+};
+#define	SC2IFP(sc)	((sc)->sc_ifp)
+
+int carp_suppress_preempt = 0;
+int carp_opts[CARPCTL_MAXID] = { 0, 1, 0, 1, 0, 0 };	/* XXX for now */
+SYSCTL_INT(_net_inet_carp, CARPCTL_ALLOW, allow, CTLFLAG_RW,
+    &carp_opts[CARPCTL_ALLOW], 0, "Accept incoming CARP packets");
+SYSCTL_INT(_net_inet_carp, CARPCTL_PREEMPT, preempt, CTLFLAG_RW,
+    &carp_opts[CARPCTL_PREEMPT], 0, "high-priority backup preemption mode");
+SYSCTL_INT(_net_inet_carp, CARPCTL_LOG, log, CTLFLAG_RW,
+    &carp_opts[CARPCTL_LOG], 0, "log bad carp packets");
+SYSCTL_INT(_net_inet_carp, CARPCTL_ARPBALANCE, arpbalance, CTLFLAG_RW,
+    &carp_opts[CARPCTL_ARPBALANCE], 0, "balance arp responses");
+SYSCTL_INT(_net_inet_carp, OID_AUTO, suppress_preempt, CTLFLAG_RD,
+    &carp_suppress_preempt, 0, "Preemption is suppressed");
+
+struct carpstats carpstats;
+SYSCTL_STRUCT(_net_inet_carp, CARPCTL_STATS, stats, CTLFLAG_RW,
+    &carpstats, carpstats,
+    "CARP statistics (struct carpstats, netinet/ip_carp.h)");
+
+struct carp_if {
+	TAILQ_HEAD(, carp_softc) vhif_vrs;
+	int vhif_nvrs;
+
+	struct ifnet 	*vhif_ifp;
+	struct lock	vhif_lock;
+};
+
+/* Get carp_if from softc. Valid after carp_set_addr{,6}. */
+#define	SC2CIF(sc)		((struct carp_if *)(sc)->sc_carpdev->if_carp)
+
+#define	CARP_LOCK_INIT(cif)	lockinit(&(cif)->vhif_lock, "carp_if", 0,  LK_NOWAIT);
+#define	CARP_LOCK_DESTROY(cif)	;
+#define	CARP_LOCK_ASSERT(cif)	;
+#define	CARP_LOCK(cif)		lockmgr(&(cif)->vhif_lock, LK_EXCLUSIVE);
+#define	CARP_UNLOCK(cif)	lockmgr(&(cif)->vhif_lock, LK_RELEASE);
+
+#define	CARP_SCLOCK(sc)		lockmgr(&SC2CIF(sc)->vhif_lock, LK_EXCLUSIVE);
+#define	CARP_SCUNLOCK(sc)	lockmgr(&SC2CIF(sc)->vhif_lock, LK_RELEASE);
+#define	CARP_SCLOCK_ASSERT(sc)	;
+
+#define	CARP_LOG(...)	do {				\
+	if (carp_opts[CARPCTL_LOG] > 0)			\
+		log(LOG_INFO, __VA_ARGS__);		\
+} while (0)
+
+#define	CARP_DEBUG(...)	do {				\
+	if (carp_opts[CARPCTL_LOG] > 1)			\
+		log(LOG_DEBUG, __VA_ARGS__);		\
+} while (0)
+
+static void	carp_hmac_prepare(struct carp_softc *);
+static void	carp_hmac_generate(struct carp_softc *, u_int32_t *,
+		    unsigned char *);
+static int	carp_hmac_verify(struct carp_softc *, u_int32_t *,
+		    unsigned char *);
+static void	carp_setroute(struct carp_softc *, int);
+static void	carp_input_c(struct mbuf *, struct carp_header *, sa_family_t);
+static int 	carp_clone_create(struct if_clone *, int);
+static void 	carp_clone_destroy(struct ifnet *);
+static void	carpdetach(struct carp_softc *, int);
+static int	carp_prepare_ad(struct mbuf *, struct carp_softc *,
+		    struct carp_header *);
+static void	carp_send_ad_all(void);
+static void	carp_send_ad(void *);
+static void	carp_send_ad_locked(struct carp_softc *);
+static void	carp_send_arp(struct carp_softc *);
+static void	carp_master_down(void *);
+static void	carp_master_down_locked(struct carp_softc *);
+static int	carp_ioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
+static int	carp_looutput(struct ifnet *, struct mbuf *, struct sockaddr *,
+		    struct rtentry *);
+static void	carp_start(struct ifnet *);
+static void	carp_setrun(struct carp_softc *, sa_family_t);
+static void	carp_set_state(struct carp_softc *, int);
+static int	carp_addrcount(struct carp_if *, struct in_ifaddr *, int);
+enum	{ CARP_COUNT_MASTER, CARP_COUNT_RUNNING };
+
+static void	carp_multicast_cleanup(struct carp_softc *);
+static int	carp_set_addr(struct carp_softc *, struct sockaddr_in *);
+static int	carp_del_addr(struct carp_softc *, struct sockaddr_in *);
+static void	carp_carpdev_state_locked(struct carp_if *);
+static void	carp_sc_state_locked(struct carp_softc *);
+#ifdef INET6
+static void	carp_send_na(struct carp_softc *);
+static int	carp_set_addr6(struct carp_softc *, struct sockaddr_in6 *);
+static int	carp_del_addr6(struct carp_softc *, struct sockaddr_in6 *);
+static void	carp_multicast6_cleanup(struct carp_softc *);
+#endif
+
+static LIST_HEAD(, carp_softc) carpif_list;
+
+struct if_clone carp_cloner = IF_CLONE_INITIALIZER(CARP_IFNAME, carp_clone_create, carp_clone_destroy, 0, IF_MAXUNIT);
+
+static eventhandler_tag if_detach_event_tag;
+
+static __inline u_int16_t
+carp_cksum(struct mbuf *m, int len)
+{
+	return (in_cksum(m, len));
+}
+
+static void
+carp_hmac_prepare(struct carp_softc *sc)
+{
+	u_int8_t version = CARP_VERSION, type = CARP_ADVERTISEMENT;
+	u_int8_t vhid = sc->sc_vhid & 0xff;
+	struct ifaddr *ifa;
+	int i;
+#ifdef INET6
+	struct in6_addr in6;
+#endif
+
+	if (sc->sc_carpdev)
+		CARP_SCLOCK(sc);
+
+	/* XXX: possible race here */
+
+	/* compute ipad from key */
+	bzero(sc->sc_pad, sizeof(sc->sc_pad));
+	bcopy(sc->sc_key, sc->sc_pad, sizeof(sc->sc_key));
+	for (i = 0; i < sizeof(sc->sc_pad); i++)
+		sc->sc_pad[i] ^= 0x36;
+
+	/* precompute first part of inner hash */
+	SHA1Init(&sc->sc_sha1);
+	SHA1Update(&sc->sc_sha1, sc->sc_pad, sizeof(sc->sc_pad));
+	SHA1Update(&sc->sc_sha1, (void *)&version, sizeof(version));
+	SHA1Update(&sc->sc_sha1, (void *)&type, sizeof(type));
+	SHA1Update(&sc->sc_sha1, (void *)&vhid, sizeof(vhid));
+#ifdef INET
+	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
+		if (ifa->ifa_addr->sa_family == AF_INET)
+			SHA1Update(&sc->sc_sha1,
+			    (void *)&ifatoia(ifa)->ia_addr.sin_addr.s_addr,
+			    sizeof(struct in_addr));
+	}
+#endif /* INET */
+#ifdef INET6
+	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
+		if (ifa->ifa_addr->sa_family == AF_INET6) {
+			in6 = ifatoia6(ifa)->ia_addr.sin6_addr;
+			in6_clearscope(&in6);
+			SHA1Update(&sc->sc_sha1, (void *)&in6, sizeof(in6));
+		}
+	}
+#endif /* INET6 */
+
+	/* convert ipad to opad */
+	for (i = 0; i < sizeof(sc->sc_pad); i++)
+		sc->sc_pad[i] ^= 0x36 ^ 0x5c;
+
+	if (sc->sc_carpdev)
+		CARP_SCUNLOCK(sc);
+}
+
+static void
+carp_hmac_generate(struct carp_softc *sc, u_int32_t counter[2],
+    unsigned char md[20])
+{
+	SHA1_CTX sha1ctx;
+
+	/* fetch first half of inner hash */
+	bcopy(&sc->sc_sha1, &sha1ctx, sizeof(sha1ctx));
+
+	SHA1Update(&sha1ctx, (void *)counter, sizeof(sc->sc_counter));
+	SHA1Final(md, &sha1ctx);
+
+	/* outer hash */
+	SHA1Init(&sha1ctx);
+	SHA1Update(&sha1ctx, sc->sc_pad, sizeof(sc->sc_pad));
+	SHA1Update(&sha1ctx, md, 20);
+	SHA1Final(md, &sha1ctx);
+}
+
+static int
+carp_hmac_verify(struct carp_softc *sc, u_int32_t counter[2],
+    unsigned char md[20])
+{
+	unsigned char md2[20];
+
+	CARP_SCLOCK_ASSERT(sc);
+
+	carp_hmac_generate(sc, counter, md2);
+
+	return (bcmp(md, md2, sizeof(md2)));
+}
+
+static void
+carp_setroute(struct carp_softc *sc, int cmd)
+{
+	struct ifaddr *ifa;
+
+	if (sc->sc_carpdev)
+		CARP_SCLOCK_ASSERT(sc);
+
+	crit_enter();
+	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
+		if (ifa->ifa_addr->sa_family == AF_INET &&
+		    sc->sc_carpdev != NULL) {
+			int count = carp_addrcount(
+			    (struct carp_if *)sc->sc_carpdev->if_carp,
+			    ifatoia(ifa), CARP_COUNT_MASTER);
+
+			if ((cmd == RTM_ADD && count == 1) ||
+			    (cmd == RTM_DELETE && count == 0))
+				rtinit(ifa, cmd, RTF_UP | RTF_HOST);
+		}
+#ifdef INET6
+		if (ifa->ifa_addr->sa_family == AF_INET6) {
+			if (cmd == RTM_ADD)
+				in6_ifaddloop(ifa);
+			else
+				in6_ifremloop(ifa);
+		}
+#endif /* INET6 */
+	}
+	crit_exit();
+
+}
+
+static int
+carp_clone_create(struct if_clone *ifc, int unit)
+{
+
+	struct carp_softc *sc;
+	struct ifnet *ifp;
+	
+        MALLOC(sc, struct carp_softc *, sizeof(*sc), M_CARP, M_WAITOK|M_ZERO); 
+	ifp = SC2IFP(sc) = kmalloc(sizeof(struct ifnet), M_IFNET, M_WAITOK|M_ZERO); 
+
+	if (ifp == NULL) {
+		FREE(sc, M_CARP);
+		return (ENOSPC);
+	}
+		
+	sc->sc_flags_backup = 0;
+	sc->sc_suppress = 0;
+	sc->sc_advbase = CARP_DFLTINTV;
+	sc->sc_vhid = -1;	/* required setting */
+	sc->sc_advskew = 0;
+	sc->sc_init_counter = 1;
+	sc->sc_naddrs = sc->sc_naddrs6 = 0; /* M_ZERO? */
+
+#ifdef INET6
+	sc->sc_im6o.im6o_multicast_hlim = CARP_DFLTTL;
+#endif
+
+/*	sc->sc_imo.imo_membership = kmalloc((sizeof(struct in_multi) * IP_MAX_MEMBERSHIPS), M_CARP,M_WAITOK);*/
+/*
+	sc->sc_imo.imo_max_memberships = IP_MAX_MEMBERSHIPS;
+	sc->sc_imo.imo_multicast_vif = -1;
+*/
+	callout_init(&sc->sc_ad_tmo);
+	callout_init(&sc->sc_md_tmo);
+	callout_init(&sc->sc_md6_tmo);
+
+	ifp->if_softc = sc;
+        if_initname(ifp, CARP_IFNAME, unit);	
+	ifp->if_mtu = ETHERMTU;
+	ifp->if_flags = IFF_LOOPBACK;
+	ifp->if_ioctl = carp_ioctl;
+	ifp->if_output = carp_looutput;
+	ifp->if_start = carp_start;
+	ifp->if_type = IFT_CARP;
+	ifp->if_snd.ifq_maxlen = ifqmaxlen;
+	ifp->if_hdrlen = 0;
+	if_attach(ifp, NULL);
+	bpfattach(ifp, DLT_NULL, sizeof(u_int));
+
+	crit_enter();
+	LIST_INSERT_HEAD(&carpif_list, sc, sc_next);
+	crit_exit();
+
+	return (0);
+}
+
+static void
+carp_clone_destroy(struct ifnet *ifp)
+{
+	struct carp_softc *sc = ifp->if_softc;
+
+	if (sc->sc_carpdev)
+		CARP_SCLOCK(sc);
+	carpdetach(sc, 1);	/* Returns unlocked. */
+
+	crit_enter();
+	LIST_REMOVE(sc, sc_next);
+	crit_exit();
+	bpfdetach(ifp);
+	if_detach(ifp);
+/*	if_free_type(ifp, IFT_ETHER);*/
+/*	kfree(sc->sc_imo.imo_membership, M_CARP); */
+	kfree(sc, M_CARP);
+}
+
+/*
+ * This function can be called on CARP interface destroy path,
+ * and in case of the removal of the underlying interface as
+ * well. We differentiate these two cases. In the latter case
+ * we do not cleanup our multicast memberships, since they
+ * are already freed. Also, in the latter case we do not
+ * release the lock on return, because the function will be
+ * called once more, for another CARP instance on the same
+ * interface.
+ */
+static void
+carpdetach(struct carp_softc *sc, int unlock)
+{
+	struct carp_if *cif;
+
+	callout_stop(&sc->sc_ad_tmo);
+	callout_stop(&sc->sc_md_tmo);
+	callout_stop(&sc->sc_md6_tmo);
+
+	if (sc->sc_suppress)
+		carp_suppress_preempt--;
+	sc->sc_suppress = 0;
+
+	if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS)
+		carp_suppress_preempt--;
+	sc->sc_sendad_errors = 0;
+
+	carp_set_state(sc, INIT);
+	SC2IFP(sc)->if_flags &= ~IFF_UP;
+	carp_setrun(sc, 0);
+	if (unlock)
+		carp_multicast_cleanup(sc);
+#ifdef INET6
+	carp_multicast6_cleanup(sc);
+#endif
+
+	if (sc->sc_carpdev != NULL) {
+		cif = (struct carp_if *)sc->sc_carpdev->if_carp;
+		CARP_LOCK_ASSERT(cif);
+		TAILQ_REMOVE(&cif->vhif_vrs, sc, sc_list);
+		if (!--cif->vhif_nvrs) {
+			ifpromisc(sc->sc_carpdev, 0);
+			sc->sc_carpdev->if_carp = NULL;
+			CARP_LOCK_DESTROY(cif);
+			FREE(cif, M_IFADDR);
+		} else if (unlock)
+			CARP_UNLOCK(cif);
+		sc->sc_carpdev = NULL;
+	}
+}
+
+/* Detach an interface from the carp. */
+static void
+carp_ifdetach(void *arg __unused, struct ifnet *ifp)
+{
+	struct carp_if *cif = (struct carp_if *)ifp->if_carp;
+	struct carp_softc *sc, *nextsc;
+
+	if (cif == NULL)
+		return;
+
+	/*
+	 * XXX: At the end of for() cycle the lock will be destroyed.
+	 */
+	CARP_LOCK(cif);
+	for (sc = TAILQ_FIRST(&cif->vhif_vrs); sc; sc = nextsc) {
+		nextsc = TAILQ_NEXT(sc, sc_list);
+		carpdetach(sc, 0);
+	}
+	CARP_UNLOCK(cif);
+}
+
+/*
+ * process input packet.
+ * we have rearranged checks order compared to the rfc,
+ * but it seems more efficient this way or not possible otherwise.
+ */
+void
+carp_input(struct mbuf *m, int hlen)
+{
+	struct ip *ip = mtod(m, struct ip *);
+	struct carp_header *ch;
+	int iplen, len;
+
+	carpstats.carps_ipackets++;
+
+	if (!carp_opts[CARPCTL_ALLOW]) {
+		m_freem(m);
+		return;
+	}
+
+	/* check if received on a valid carp interface */
+	if (m->m_pkthdr.rcvif->if_carp == NULL) {
+		carpstats.carps_badif++;
+		CARP_LOG("carp_input: packet received on non-carp "
+		    "interface: %s\n",
+		    m->m_pkthdr.rcvif->if_xname);
+		m_freem(m);
+		return;
+	}
+
+	/* verify that the IP TTL is 255.  */
+	if (ip->ip_ttl != CARP_DFLTTL) {
+		carpstats.carps_badttl++;
+		CARP_LOG("carp_input: received ttl %d != 255i on %s\n",
+		    ip->ip_ttl,
+		    m->m_pkthdr.rcvif->if_xname);
+		m_freem(m);
+		return;
+	}
+
+	iplen = ip->ip_hl << 2;
+
+	if (m->m_pkthdr.len < iplen + sizeof(*ch)) {
+		carpstats.carps_badlen++;
+		CARP_LOG("carp_input: received len %zd < "
+		    "sizeof(struct carp_header)\n",
+		    m->m_len - sizeof(struct ip));
+		m_freem(m);
+		return;
+	}
+
+	if (iplen + sizeof(*ch) < m->m_len) {
+		if ((m = m_pullup(m, iplen + sizeof(*ch))) == NULL) {
+			carpstats.carps_hdrops++;
+			CARP_LOG("carp_input: pullup failed\n");
+			return;
+		}
+		ip = mtod(m, struct ip *);
+	}
+	ch = (struct carp_header *)((char *)ip + iplen);
+
+	/*
+	 * verify that the received packet length is
+	 * equal to the CARP header
+	 */
+	len = iplen + sizeof(*ch);
+	if (len > m->m_pkthdr.len) {
+		carpstats.carps_badlen++;
+		CARP_LOG("carp_input: packet too short %d on %s\n",
+		    m->m_pkthdr.len,
+		    m->m_pkthdr.rcvif->if_xname);
+		m_freem(m);
+		return;
+	}
+
+	if ((m = m_pullup(m, len)) == NULL) {
+		carpstats.carps_hdrops++;
+		return;
+	}
+	ip = mtod(m, struct ip *);
+	ch = (struct carp_header *)((char *)ip + iplen);
+
+	/* verify the CARP checksum */
+	m->m_data += iplen;
+	if (carp_cksum(m, len - iplen)) {
+		carpstats.carps_badsum++;
+		CARP_LOG("carp_input: checksum failed on %s\n",
+		    m->m_pkthdr.rcvif->if_xname);
+		m_freem(m);
+		return;
+	}
+	m->m_data -= iplen;
+
+	carp_input_c(m, ch, AF_INET);
+}
+
+#ifdef INET6
+int
+carp6_input(struct mbuf **mp, int *offp, int proto)
+{
+	struct mbuf *m = *mp;
+	struct ip6_hdr *ip6 = mtod(m, struct ip6_hdr *);
+	struct carp_header *ch;
+	u_int len;
+
+	carpstats.carps_ipackets6++;
+
+	if (!carp_opts[CARPCTL_ALLOW]) {
+		m_freem(m);
+		return (IPPROTO_DONE);
+	}
+
+	/* check if received on a valid carp interface */
+	if (m->m_pkthdr.rcvif->if_carp == NULL) {
+		carpstats.carps_badif++;
+		CARP_LOG("carp6_input: packet received on non-carp "
+		    "interface: %s\n",
+		    m->m_pkthdr.rcvif->if_xname);
+		m_freem(m);
+		return (IPPROTO_DONE);
+	}
+
+	/* verify that the IP TTL is 255 */
+	if (ip6->ip6_hlim != CARP_DFLTTL) {
+		carpstats.carps_badttl++;
+		CARP_LOG("carp6_input: received ttl %d != 255 on %s\n",
+		    ip6->ip6_hlim,
+		    m->m_pkthdr.rcvif->if_xname);
+		m_freem(m);
+		return (IPPROTO_DONE);
+	}
+
+	/* verify that we have a complete carp packet */
+	len = m->m_len;
+	IP6_EXTHDR_GET(ch, struct carp_header *, m, *offp, sizeof(*ch));
+	if (ch == NULL) {
+		carpstats.carps_badlen++;
+		CARP_LOG("carp6_input: packet size %u too small\n", len);
+		return (IPPROTO_DONE);
+	}
+
+
+	/* verify the CARP checksum */
+	m->m_data += *offp;
+	if (carp_cksum(m, sizeof(*ch))) {
+		carpstats.carps_badsum++;
+		CARP_LOG("carp6_input: checksum failed, on %s\n",
+		    m->m_ROTO_DONE);
+	}
+	m->m_data -= *offp;
+
+	carp_input_c(m, ch, AF_INET6);
+	return (IPPROTO_DONE);
+}
+#endif /* INET6 */
+
+static void
+carp_input_c(struct mbuf *m, struct carp_header *ch, sa_family_t af)
+{
+	struct ifnet *ifp = m->m_pkthdr.rcvif;
+	struct carp_softc *sc;
+	u_int64_t tmp_counter;
+	struct timeval sc_tv, ch_tv;
+
+	/* verify that the VHID is valid on the receiving interface */
+	CARP_LOCK(ifp->if_carp);
+	TAILQ_FOREACH(sc, &((struct carp_if *)ifp->if_carp)->vhif_vrs, sc_list)
+		if (sc->sc_vhid == ch->carp_vhid)
+			break;
+
+	if (!sc || !((SC2IFP(sc)->if_flags & IFF_UP) && (SC2IFP(sc)->if_flags & IFF_RUNNING))) {
+		carpstats.carps_badvhid++;
+		CARP_UNLOCK(ifp->if_carp);
+		m_freem(m);
+		return;
+	}
+
+	getmicrotime(&SC2IFP(sc)->if_lastchange);
+	SC2IFP(sc)->if_ipackets++;
+	SC2IFP(sc)->if_ibytes += m->m_pkthdr.len;
+
+	if (SC2IFP(sc)->if_bpf) {
+		struct ip *ip = mtod(m, struct ip *);
+
+		/* BPF wants net byte order */
+		ip->ip_len = htons(ip->ip_len + (ip->ip_hl << 2));
+		ip->ip_off = htons(ip->ip_off);
+		bpf_mtap(SC2IFP(sc)->if_bpf, m);
+	}
+
+	/* verify the CARP version. */
+	if (ch->carp_version != CARP_VERSION) {
+		carpstats.carps_badver++;
+		SC2IFP(sc)->if_ierrors++;
+		CARP_UNLOCK(ifp->if_carp);
+		CARP_LOG("%s; invalid version %d\n",
+		    SC2IFP(sc)->if_xname,
+		    ch->carp_version);
+		m_freem(m);
+		return;
+	}
+
+	/* verify the hash */
+	if (carp_hmac_verify(sc, ch->carp_counter, ch->carp_md)) {
+		carpstats.carps_badauth++;
+		SC2IFP(sc)->if_ierrors++;
+		CARP_UNLOCK(ifp->if_carp);
+		CARP_LOG("%s: incorrect hash\n", SC2IFP(sc)->if_xname);
+		m_freem(m);
+		return;
+	}
+
+	tmp_counter = ntohl(ch->carp_counter[0]);
+	tmp_counter = tmp_counter<<32;
+	tmp_counter += ntohl(ch->carp_counter[1]);
+
+	/* XXX Replay protection goes here */
+
+	sc->sc_init_counter = 0;
+	sc->sc_counter = tmp_counter;
+
+	sc_tv.tv_sec = sc->sc_advbase;
+	if (carp_suppress_preempt && sc->sc_advskew <  240)
+		sc_tv.tv_usec = 240 * 1000000 / 256;
+	else
+		sc_tv.tv_usec = sc->sc_advskew * 1000000 / 256;
+	ch_tv.tv_sec = ch->carp_advbase;
+	ch_tv.tv_usec = ch->carp_advskew * 1000000 / 256;
+
+	switch (sc->sc_state) {
+	case INIT:
+		break;
+	case MASTER:
+		/*
+		 * If we receive an advertisement from a master who's going to
+		 * be more frequent than us, go into BACKUP state.
+		 */
+		if (timevalcmp(&sc_tv, &ch_tv, >) ||
+		    timevalcmp(&sc_tv, &ch_tv, ==)) {
+			callout_stop(&sc->sc_ad_tmo);
+			CARP_DEBUG("%s: MASTER -> BACKUP "
+			   "(more frequent advertisement received)\n",
+			   SC2IFP(sc)->if_xname);
+			carp_set_state(sc, BACKUP);
+			carp_setrun(sc, 0);
+			carp_setroute(sc, RTM_DELETE);
+		}
+		break;
+	case BACKUP:
+		/*
+		 * If we're pre-empting masters who advertise slower than us,
+		 * and this one claims to be slower, treat him as down.
+		 */
+		if (carp_opts[CARPCTL_PREEMPT] &&
+		    timevalcmp(&sc_tv, &ch_tv, <)) {
+			CARP_DEBUG("%s: BACKUP -> MASTER "
+			    "(preempting a slower master)\n",
+			    SC2IFP(sc)->if_xname);
+			carp_master_down_locked(sc);
+			break;
+		}
+
+		/*
+		 *  If the master is going to advertise at such a low frequency
+		 *  that he's guaranteed to time out, we'd might as well just
+		 *  treat him as timed out now.
+		 */
+		sc_tv.tv_sec = sc->sc_advbase * 3;
+		if (timevalcmp(&sc_tv, &ch_tv, <)) {
+			CARP_DEBUG("%s: BACKUP -> MASTER "
+			    "(master timed out)\n",
+			    SC2IFP(sc)->if_xname);
+			carp_master_down_locked(sc);
+			break;
+		}
+
+		/*
+		 * Otherwise, we reset the counter and wait for the next
+		 * advertisement.
+		 */
+		carp_setrun(sc, af);
+		break;
+	}
+
+	CARP_UNLOCK(ifp->if_carp);
+
+	m_freem(m);
+	return;
+}
+
+static int
+carp_prepare_ad(struct mbuf *m, struct carp_softc *sc, struct carp_header *ch)
+{
+	struct m_tag *mtag;
+	struct ifnet *ifp = SC2IFP(sc);
+
+	if (sc->sc_init_counter) {
+		/* this could also be seconds since unix epoch */
+		sc->sc_counter = karc4random();
+		sc->sc_counter = sc->sc_counter << 32;
+		sc->sc_counter += karc4random();
+	} else
+		sc->sc_counter++;
+
+	ch->carp_counter[0] = htonl((sc->sc_counter>>32)&0xffffffff);
+	ch->carp_counter[1] = htonl(sc->sc_counter&0xffffffff);
+
+	carp_hmac_generate(sc, ch->carp_counter, ch->carp_md);
+
+	/* Tag packet for carp_output */
+	mtag = m_tag_get(PACKET_TAG_CARP, sizeof(struct ifnet *), M_NOWAIT);
+	if (mtag == NULL) {
+		m_freem(m);
+		SC2IFP(sc)->if_oerrors++;
+		return (ENOMEM);
+	}
+	bcopy(&ifp, (caddr_t)(mtag + 1), sizeof(struct ifnet *));
+	m_tag_prepend(m, mtag);
+
+	return (0);
+}
+
+static void
+carp_send_ad_all(void)
+{
+	struct carp_softc *sc;
+
+	LIST_FOREACH(sc, &carpif_list, sc_next) {
+		if (sc->sc_carpdev == NULL)
+			continue;
+		CARP_SCLOCK(sc);
+		if ((SC2IFP(sc)->if_flags & IFF_UP) && (SC2IFP(sc)->if_flags & IFF_RUNNING) &&
+		     sc->sc_state == MASTER)
+			carp_send_ad_locked(sc);
+		CARP_SCUNLOCK(sc);
+	}
+}
+
+static void
+carp_send_ad(void *v)
+{
+	struct carp_softc *sc = v;
+
+	CARP_SCLOCK(sc);
+	carp_send_ad_locked(sc);
+	CARP_SCUNLOCK(sc);
+}
+
+static void
+carp_send_ad_locked(struct carp_softc *sc)
+{
+	struct carp_header ch;
+	struct timeval tv;
+	struct carp_header *ch_ptr;
+	struct mbuf *m;
+	int len, advbase, advskew;
+
+
+	/* bow out if we've lost our UPness or RUNNINGuiness */
+	if (!((SC2IFP(sc)->if_flags & IFF_UP) && (SC2IFP(sc)->if_flags & IFF_RUNNING))) {
+		advbase = 255;
+		advskew = 255;
+	} else {
+		advbase = sc->sc_advbase;
+		if (!carp_suppress_preempt || sc->sc_advskew > 240)
+			advskew = sc->sc_advskew;
+		else
+			advskew = 240;
+		tv.tv_sec = advbase;
+		tv.tv_usec = advskew * 1000000 / 256;
+	}
+
+	ch.carp_version = CARP_VERSION;
+	ch.carp_type = CARP_ADVERTISEMENT;
+	ch.carp_vhid = sc->sc_vhid;
+	ch.carp_advbase = advbase;
+	ch.carp_advskew = advskew;
+	ch.carp_authlen = 7;	/* XXX DEFINE */
+	ch.carp_pad1 = 0;	/* must be zero */
+	ch.carp_cksum = 0;
+
+#ifdef INET
+	if (sc->sc_ia) {
+		struct ip *ip;
+
+		MGETHDR(m, M_NOWAIT, MT_HEADER);
+		if (m == NULL) {
+			SC2IFP(sc)->if_oerrors++;
+			carpstats.carps_onomem++;
+			/* XXX maybe less ? */
+			if (advbase != 255 || advskew != 255)
+				callout_reset(&sc->sc_ad_tmo, tvtohz_high(&tv),
+				    carp_send_ad, sc);
+			return;
+		}
+		len = sizeof(*ip) + sizeof(ch);
+		m->m_pkthdr.len = len;
+		m->m_pkthdr.rcvif = NULL;
+		m->m_len = len;
+		MH_ALIGN(m, m->m_len);
+		m->m_flags |= M_MCAST;
+		ip = mtod(m, struct ip *);
+		ip->ip_v = IPVERSION;
+		ip->ip_hl = sizeof(*ip) >> 2;
+		ip->ip_tos = IPTOS_LOWDELAY;
+		ip->ip_len = len;
+		ip->ip_id = ip_newid();
+		ip->ip_off = IP_DF;
+		ip->ip_ttl = CARP_DFLTTL;
+		ip->ip_p = IPPROTO_CARP;
+		ip->ip_sum = 0;
+		ip->ip_src.s_addr = sc->sc_ia->ia_addr.sin_addr.s_addr;
+		ip->ip_dst.s_addr = htonl(INADDR_CARP_GROUP);
+
+		ch_ptr = (struct carp_header *)(&ip[1]);
+		bcopy(&ch, ch_ptr, sizeof(ch));
+		if (carp_prepare_ad(m, sc, ch_ptr))
+			return;
+
+		m->m_data += sizeof(*ip);
+		ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip));
+		m->m_data -= sizeof(*ip);
+
+		getmicrotime(&SC2IFP(sc)->if_lastchange);
+		SC2IFP(sc)->if_opackets++;
+		SC2IFP(sc)->if_obytes += len;
+		carpstats.carps_opackets++;
+
+		if (ip_output(m, NULL, NULL, IP_RAWOUTPUT, &sc->sc_imo, NULL)) {
+			SC2IFP(sc)->if_oerrors++;
+			if (sc->sc_sendad_errors < INT_MAX)
+				sc->sc_sendad_errors++;
+			if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS) {
+				carp_suppress_preempt++;
+				if (carp_suppress_preempt == 1) {
+					CARP_SCUNLOCK(sc);
+					carp_send_ad_all();
+					CARP_SCLOCK(sc);
+				}
+			}
+			sc->sc_sendad_success = 0;
+		} else {
+			if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS) {
+				if (++sc->sc_sendad_success >=
+				    CARP_SENDAD_MIN_SUCCESS) {
+					carp_suppress_preempt--;
+					sc->sc_sendad_errors = 0;
+				}
+			} else
+				sc->sc_sendad_errors = 0;
+		}
+	}
+#endif /* INET */
+#ifdef INET6
+	if (sc->sc_ia6) {
+		struct ip6_hdr *ip6;
+
+		MGETHDR(m, M_NOWAIT, MT_HEADER);
+		if (m == NULL) {
+			SC2IFP(sc)->if_oerrors++;
+			carpstats.carps_onomem++;
+			/* XXX maybe less ? */
+			if (advbase != 255 || advskew != 255)
+				callout_reset(&sc->sc_ad_tmo, tvtohz_high(&tv),
+				    carp_send_ad, sc);
+			return;
+		}
+		len = sizeof(*ip6) + sizeof(ch);
+		m->m_pkthdr.len = len;
+		m->m_pkthdr.rcvif = NULL;
+		m->m_len = len;
+		MH_ALIGN(m, m->m_len);
+		m->m_flags |= M_MCAST;
+		ip6 = mtod(m, struct ip6_hdr *);
+		bzero(ip6, sizeof(*ip6));
+		ip6->ip6_vfc |= IPV6_VERSION;
+		ip6->ip6_hlim = CARP_DFLTTL;
+		ip6->ip6_nxt = IPPROTO_CARP;
+		bcopy(&sc->sc_ia6->ia_addr.sin6_addr, &ip6->ip6_src,
+		    sizeof(struct in6_addr));
+		/* set the multicast destination */
+
+		ip6->ip6_dst.s6_addr16[0] = htons(0xff02);
+		ip6->ip6_dst.s6_addr8[15] = 0x12;
+		if (in6_setscope(&ip6->ip6_dst, sc->sc_carpdev, NULL) != 0) {
+			SC2IFP(sc)->if_oerrors++;
+			m_freem(m);
+			CARP_LOG("%s: in6_setscope failed\n", __func__);
+			return;
+		}
+
+		ch_ptr = (struct carp_header *)(&ip6[1]);
+		bcopy(&ch, ch_ptr, sizeof(ch));
+		if (carp_prepare_ad(m, sc, ch_ptr))
+			return;
+
+		m->m_data += sizeof(*ip6);
+		ch_ptr->carp_cksum = carp_cksum(m, len - sizeof(*ip6));
+		m->m_data -= sizeof(*ip6);
+
+		getmicrotime(&SC2IFP(sc)->if_lastchange);
+		SC2IFP(sc)->if_opackets++;
+		SC2IFP(sc)->if_obytes += len;
+		carpstats.carps_opackets6++;
+
+		if (ip6_output(m, NULL, NULL, 0, &sc->sc_im6o, NULL, NULL)) {
+			SC2IFP(sc)->if_oerrors++;
+			if (sc->sc_sendad_errors < INT_MAX)
+				sc->sc_sendad_errors++;
+			if (sc->sc_sendad_errors == CARP_SENDAD_MAX_ERRORS) {
+				carp_suppress_preempt++;
+				if (carp_suppress_preempt == 1) {
+					CARP_SCUNLOCK(sc);
+					carp_send_ad_all();
+					CARP_SCLOCK(sc);
+				}
+			}
+			sc->sc_sendad_success = 0;
+		} else {
+			if (sc->sc_sendad_errors >= CARP_SENDAD_MAX_ERRORS) {
+				if (++sc->sc_sendad_success >=
+				    CARP_SENDAD_MIN_SUCCESS) {
+					carp_suppress_preempt--;
+					sc->sc_sendad_errors = 0;
+				}
+			} else
+				sc->sc_sendad_errors = 0;
+		}
+	}
+#endif /* INET6 */
+
+	if (advbase != 255 || advskew != 255)
+		callout_reset(&sc->sc_ad_tmo, tvtohz_high(&tv),
+		    carp_send_ad, sc);
+
+}
+
+/*
+ * Broadcast a gratuitous ARP request containing
+ * the virtual router MAC address for each IP address
+ * associated with the virtual router.
+ */
+static void
+carp_send_arp(struct carp_softc *sc)
+{
+	struct ifaddr *ifa;
+
+	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
+
+		if (ifa->ifa_addr->sa_family != AF_INET)
+			continue;
+		lwkt_serialize_enter(sc->sc_carpdev->if_serializer);
+	        arp_ifinit2(sc->sc_carpdev, ifa, IF_LLADDR(sc->sc_ifp));	
+		lwkt_serialize_exit(sc->sc_carpdev->if_serializer); 
+
+		DELAY(1000);	/* XXX */
+	}
+}
+
+#ifdef INET6
+static void
+carp_send_na(struct carp_softc *sc)
+{
+	struct ifaddr *ifa;
+	struct in6_addr *in6;
+	static struct in6_addr mcast = IN6ADDR_LINKLOCAL_ALLNODES_INIT;
+
+	TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
+
+		if (ifa->ifa_addr->sa_family != AF_INET6)
+			continue;
+
+		in6 = &ifatoia6(ifa)->ia_addr.sin6_addr;
+		nd6_na_output(sc->sc_carpdev, &mcast, in6,
+		    ND_NA_FLAG_OVERRIDE, 1, NULL);
+		DELAY(1000);	/* XXX */
+	}
+}
+#endif /* INET6 */
+
+static int
+carp_addrcount(struct carp_if *cif, struct in_ifaddr *ia, int type)
+{
+	struct carp_softc *vh;
+	struct ifaddr *ifa;
+	int count = 0;
+
+	CARP_LOCK_ASSERT(cif);
+
+	TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
+		if ((type == CARP_COUNT_RUNNING &&
+		    (SC2IFP(vh)->if_flags & IFF_UP) && (SC2IFP(vh)->if_flags & IFF_RUNNING)) ||
+		    (type == CARP_COUNT_MASTER && vh->sc_state == MASTER)) {
+			TAILQ_FOREACH(ifa, &SC2IFP(vh)->if_addrlist,
+			    ifa_list) {
+				if (ifa->ifa_addr->sa_family == AF_INET &&
+				    ia->ia_addr.sin_addr.s_addr ==
+				    ifatoia(ifa)->ia_addr.sin_addr.s_addr)
+					count++;
+			}
+		}
+	}
+	return (count);
+}
+
+int
+carp_iamatch(void *v, struct in_ifaddr *ia,
+    struct in_addr *isaddr, u_int8_t **enaddr)
+{
+	struct carp_if *cif = v;
+	struct carp_softc *vh;
+	int index, count = 0;
+	struct ifaddr *ifa;
+
+	CARP_LOCK(cif);
+
+	if (carp_opts[CARPCTL_ARPBALANCE]) {
+		/*
+		 * XXX proof of concept implementation.
+		 * We use the source ip to decide which virtual host should
+		 * handle the request. If we're master of that virtual host,
+		 * then we respond, otherwise, just drop the arp packet on
+		 * the floor.
+		 */
+		count = carp_addrcount(cif, ia, CARP_COUNT_RUNNING);
+		if (count == 0) {
+			/* should never reach this */
+			CARP_UNLOCK(cif);
+			return (0);
+		}
+
+		/* this should be a hash, like pf_hash() */
+		index = ntohl(isaddr->s_addr) % count;
+		count = 0;
+
+		TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
+			if ((SC2IFP(vh)->if_flags & IFF_UP) && (SC2IFP(vh)->if_flags & IFF_RUNNING)) {
+				TAILQ_FOREACH(ifa, &SC2IFP(vh)->if_addrlist,
+				    ifa_list) {
+					if (ifa->ifa_addr->sa_family ==
+					    AF_INET &&
+					    ia->ia_addr.sin_addr.s_addr ==
+					    ifatoia(ifa)->ia_addr.sin_addr.s_addr) {
+						if (count == index) {
+							if (vh->sc_state ==
+							    MASTER) {
+								*enaddr = IF_LLADDR(vh->sc_ifp);
+								CARP_UNLOCK(cif);
+								return (1);
+							} else {
+								CARP_UNLOCK(cif);
+								return (0);
+							}
+						}
+						count++;
+					}
+				}
+			}
+		}
+	} else {
+		TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
+			if ((SC2IFP(vh)->if_flags & IFF_UP) && (SC2IFP(vh)->if_flags & IFF_RUNNING) &&
+			    vh->sc_state == MASTER) {
+				*enaddr = IF_LLADDR(vh->sc_ifp);
+				CARP_UNLOCK(cif);
+				return (1);
+			}
+		}
+	}
+	CARP_UNLOCK(cif);
+	return(0);
+}
+
+#ifdef INET6
+struct ifaddr *
+carp_iamatch6(void *v, struct in6_addr *taddr)
+{
+	struct carp_if *cif = v;
+	struct carp_softc *vh;
+	struct ifaddr *ifa;
+
+	CARP_LOCK(cif);
+	TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list) {
+		TAILQ_FOREACH(ifa, &SC2IFP(vh)->if_addrlist, ifa_list) {
+			if (IN6_ARE_ADDR_EQUAL(taddr,
+			    &ifatoia6(ifa)->ia_addr.sin6_addr) &&
+ 			    (SC2IFP(vh)->if_flags & IFF_UP) && (SC2IFP(vh)->if_flags & IFF_RUNNING) &&
+			    vh->sc_state == MASTER) {
+			    	CARP_UNLOCK(cif);
+				return (ifa);
+			}
+		}
+	}
+	CARP_UNLOCK(cif);
+	
+	return (NULL);
+}
+
+void *
+carp_macmatch6(void *v, struct mbuf *m, const struct in6_addr *taddr)
+{
+	struct m_tag *mtag;
+	struct carp_if *cif = v;
+	struct carp_softc *sc;
+	struct ifaddr *ifa;
+
+	CARP_LOCK(cif);
+	TAILQ_FOREACH(sc, &cif->vhif_vrs, sc_list) {
+		TAILQ_FOREACH(ifa, &SC2IFP(sc)->if_addrlist, ifa_list) {
+			if (IN6_ARE_ADDR_EQUAL(taddr,
+			    &ifatoia6(ifa)->ia_addr.sin6_addr) &&
+ 			    (SC2IFP(sc)->if_flags & IFF_UP) && (SC2IFP(sc)->if_flags & IFF_RUNNING)) {
+				struct ifnet *ifp = SC2IFP(sc);
+				mtag = m_tag_get(PACKET_TAG_CARP,
+				    sizeof(struct ifnet *), M_NOWAIT);
+				if (mtag == NULL) {
+					/* better a bit than nothing */
+					CARP_UNLOCK(cif);
+					return (IF_LLADDR(sc->sc_ifp));
+				}
+				bcopy(&ifp, (caddr_t)(mtag + 1),
+				    sizeof(struct ifnet *));
+				m_tag_prepend(m, mtag);
+
+				CARP_UNLOCK(cif);
+				return (IF_LLADDR(sc->sc_ifp));
+			}
+		}
+	}
+	CARP_UNLOCK(cif);
+
+	return (NULL);
+}
+#endif
+
+struct ifnet *
+carp_forus(void *v, void *dhost)
+{
+	struct carp_if *cif = v;
+	struct carp_softc *vh;
+	u_int8_t *ena = dhost;
+	
+	/**
+         * XXX: See here for check on MAC adr is not for virtual use
+         *
+         **/
+
+	if (ena[0] || ena[1] || ena[2] != 0x5e || ena[3] || ena[4] != 1)
+	{
+		return (NULL);
+	}
+
+	CARP_LOCK(cif);
+	TAILQ_FOREACH(vh, &cif->vhif_vrs, sc_list)
+		if ((SC2IFP(vh)->if_flags & IFF_UP) && (SC2IFP(vh)->if_flags & IFF_RUNNING) &&
+		    vh->sc_state == MASTER &&
+		    !bcmp(dhost, IF_LLADDR(vh->sc_ifp), ETHER_ADDR_LEN)) {
+		    	CARP_UNLOCK(cif);
+			return (SC2IFP(vh));
+		}
+
+    	CARP_UNLOCK(cif);
+	return (NULL);
+}
+
+static void
+carp_master_down(void *v)
+{
+	struct carp_softc *sc = v;
+
+	lwkt_serialize_enter(sc->sc_ifp->if_serializer);
+	carp_master_down_locked(sc);
+	lwkt_serialize_exit(sc->sc_ifp->if_serializer);
+}
+
+static void
+carp_master_down_locked(struct carp_softc *sc)
+{
+	if (sc->sc_carpdev)
+		CARP_SCLOCK_ASSERT(sc);
+
+	switch (sc->sc_state) {
+	case INIT:
+		kprintf("%s: master_down event in INIT state\n",
+		    SC2IFP(sc)->if_xname);
+		break;
+	case MASTER:
+		break;
+	case BACKUP:
+		carp_set_state(sc, MASTER);
+		carp_send_ad_locked(sc);
+		carp_send_arp(sc);
+#ifdef INET6
+		carp_send_na(sc);
+#endif /* INET6 */
+		carp_setrun(sc, 0);
+		carp_setroute(sc, RTM_ADD);
+		break;
+	}
+}
+
+/*
+ * When in backup state, af indicates whether to reset the master down timer
+ * for v4 or v6. If it's set to zero, reset the ones which are already pending.
+ */
+static void
+carp_setrun(struct carp_softc *sc, sa_family_t af)
+{
+	struct timeval tv;
+
+	if (sc->sc_carpdev == NULL) {
+		SC2IFP(sc)->if_flags &= ~IFF_RUNNING;
+		carp_set_state(sc, INIT);
+		return;
+	}
+
+	if (SC2IFP(sc)->if_flags & IFF_UP &&
+	    sc->sc_vhid > 0 && (sc->sc_naddrs || sc->sc_naddrs6))
+		SC2IFP(sc)->if_flags |= IFF_RUNNING;
+	else {
+		SC2IFP(sc)->if_flags &= ~IFF_RUNNING;
+		carp_setroute(sc, RTM_DELETE);
+		return;
+	}
+
+	switch (sc->sc_state) {
+	case INIT:
+		if (carp_opts[CARPCTL_PREEMPT] && !carp_suppress_preempt) {
+			carp_send_ad_locked(sc);
+			carp_send_arp(sc);
+#ifdef INET6
+			carp_send_na(sc);
+#endif /* INET6 */
+			CARP_DEBUG("%s: INIT -> MASTER (preempting)\n",
+			    SC2IFP(sc)->if_xname);
+			carp_set_state(sc, MASTER);
+			carp_setroute(sc, RTM_ADD);
+		} else {
+			CARP_DEBUG("%s: INIT -> BACKUP\n", SC2IFP(sc)->if_xname);
+			carp_set_state(sc, BACKUP);
+			carp_setroute(sc, RTM_DELETE);
+			carp_setrun(sc, 0);
+		}
+		break;
+	case BACKUP:
+		callout_stop(&sc->sc_ad_tmo);
+		tv.tv_sec = 3 * sc->sc_advbase;
+		tv.tv_usec = sc->sc_advskew * 1000000 / 256;
+		switch (af) {
+#ifdef INET
+		case AF_INET:
+			callout_reset(&sc->sc_md_tmo, tvtohz_high(&tv),
+			    carp_master_down, sc);
+			break;
+#endif /* INET */
+#ifdef INET6
+		case AF_INET6:
+			callout_reset(&sc->sc_md6_tmo, tvtohz_high(&tv),
+			    carp_master_down, sc);
+			break;
+#endif /* INET6 */
+		default:
+			if (sc->sc_naddrs)
+				callout_reset(&sc->sc_md_tmo, tvtohz_high(&tv),
+				    carp_master_down, sc);
+			if (sc->sc_naddrs6)
+				callout_reset(&sc->sc_md6_tmo, tvtohz_high(&tv),
+				    carp_master_down, sc);
+			break;
+		}
+		break;
+	case MASTER:
+		tv.tv_sec = sc->sc_advbase;
+		tv.tv_usec = sc->sc_advskew * 1000000 / 256;
+		callout_reset(&sc->sc_ad_tmo, tvtohz_high(&tv),
+		    carp_send_ad, sc);
+		break;
+	}
+}
+
+static void
+carp_multicast_cleanup(struct carp_softc *sc)
+{
+	struct ip_moptions *imo = &sc->sc_imo;
+	u_int16_t n = imo->imo_num_memberships;
+
+	/* Clean up our own multicast memberships */
+	while (n-- > 0) {
+		if (imo->imo_membership[n] != NULL) {
+			in_delmulti(imo->imo_membership[n]);
+			imo->imo_membership[n] = NULL;
+		}
+	}
+	imo->imo_num_memberships = 0;
+	imo->imo_multicast_ifp = NULL;
+}
+
+#ifdef INET6
+static void
+carp_multicast6_cleanup(struct carp_softc *sc)
+{
+	struct ip6_moptions *im6o = &sc->sc_im6o;
+
+	while (!LIST_EMPTY(&im6o->im6o_memberships)) {
+		struct in6_multi_mship *imm =
+		    LIST_FIRST(&im6o->im6o_memberships);
+
+		LIST_REMOVE(imm, i6mm_chain);
+		in6_leavegroup(imm);
+	}
+	im6o->im6o_multicast_ifp = NULL;
+}
+#endif
+
+static int
+carp_set_addr(struct carp_softc *sc, struct sockaddr_in *sin)
+{
+	struct ifnet *ifp;
+	struct carp_if *cif;
+	struct in_ifaddr *ia, *ia_if;
+	struct ip_moptions *imo = &sc->sc_imo;
+	struct in_addr addr;
+	u_long iaddr = htonl(sin->sin_addr.s_addr);
+	int own, error;
+	
+	if (sin->sin_addr.s_addr == 0) 
+	{
+		if (!(SC2IFP(sc)->if_flags & IFF_UP))
+		{
+			carp_set_state(sc, INIT);
+		}
+		if (sc->sc_naddrs)
+		{
+			SC2IFP(sc)->if_flags |= IFF_UP;
+		}
+		carp_setrun(sc, 0);
+		return (0);
+	}
+	/* we have to do it by hands to check we won't match on us */
+	ia_if = NULL; own = 0;
+	TAILQ_FOREACH(ia, &in_ifaddrhead, ia_link) {
+		/* and, yeah, we need a multicast-capable iface too */
+		if (ia->ia_ifp != SC2IFP(sc) &&
+		    (ia->ia_ifp->if_flags & IFF_MULTICAST) &&
+		    (iaddr & ia->ia_subnetmask) == ia->ia_subnet) {
+			if (!ia_if)
+				ia_if = ia;
+			if (sin->sin_addr.s_addr ==
+			    ia->ia_addr.sin_addr.s_addr)
+				own++;
+		}
+	}
+	
+	
+	if (!ia_if)
+		return (EADDRNOTAVAIL);
+
+	ia = ia_if;
+	ifp = ia->ia_ifp;
+
+	if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0 ||
+	    (imo->imo_multicast_ifp && imo->imo_multicast_ifp != ifp))
+		return (EADDRNOTAVAIL);
+
+	if (imo->imo_num_memberships == 0) {
+		addr.s_addr = htonl(INADDR_CARP_GROUP);
+		if ((imo->imo_membership[0] = in_addmulti(&addr, ifp)) == NULL)
+			return (ENOBUFS);
+		imo->imo_num_memberships++;
+		imo->imo_multicast_ifp = ifp;
+		imo->imo_multicast_ttl = CARP_DFLTTL;
+		imo->imo_multicast_loop = 0;
+	}
+
+	if (!ifp->if_carp) {
+
+		MALLOC(cif, struct carp_if *, sizeof(*cif), M_CARP,
+		    M_WAITOK|M_ZERO);
+		if (!cif) {
+			error = ENOBUFS;
+			goto cleanup;
+		}
+		if ((error = ifpromisc(ifp, 1))) {
+			FREE(cif, M_CARP);
+			goto cleanup;
+		}
+		
+		CARP_LOCK_INIT(cif);
+		CARP_LOCK(cif);
+		cif->vhif_ifp = ifp;
+		TAILQ_INIT(&cif->vhif_vrs);
+		ifp->if_carp = cif;
+
+	} else {
+		struct carp_softc *vr;
+
+		cif = (struct carp_if *)ifp->if_carp;
+		CARP_LOCK(cif);
+		TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list)
+			if (vr != sc && vr->sc_vhid == sc->sc_vhid) {
+				CARP_UNLOCK(cif);
+				error = EINVAL;
+				goto cleanup;
+			}
+	}
+	sc->sc_ia = ia;
+	sc->sc_carpdev = ifp;
+
+	{ /* XXX prevent endless loop if already in queue */
+	struct carp_softc *vr, *after = NULL;
+	int myself = 0;
+	cif = (struct carp_if *)ifp->if_carp;
+
+	/* XXX: cif should not change, right? So we still hold the lock */
+	CARP_LOCK_ASSERT(cif);
+
+	TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list) {
+		if (vr == sc)
+			myself = 1;
+		if (vr->sc_vhid < sc->sc_vhid)
+			after = vr;
+	}
+
+	if (!myself) {
+		/* We're trying to keep things in order */
+		if (after == NULL) {
+			TAILQ_INSERT_TAIL(&cif->vhif_vrs, sc, sc_list);
+		} else {
+			TAILQ_INSERT_AFTER(&cif->vhif_vrs, after, sc, sc_list);
+		}
+		cif->vhif_nvrs++;
+	}
+	}
+
+	sc->sc_naddrs++;
+	SC2IFP(sc)->if_flags |= IFF_UP;
+	if (own)
+		sc->sc_advskew = 0;
+
+
+	carp_sc_state_locked(sc);
+	carp_setrun(sc, 0);
+
+	CARP_UNLOCK(cif);
+	
+	return (0);
+
+cleanup:
+	in_delmulti(imo->imo_membership[--imo->imo_num_memberships]);
+	return (error);
+
+}
+
+static int
+carp_del_addr(struct carp_softc *sc, struct sockaddr_in *sin)
+{
+	int error = 0;
+
+	if (!--sc->sc_naddrs) {
+		struct carp_if *cif = (struct carp_if *)sc->sc_carpdev->if_carp;
+		struct ip_moptions *imo = &sc->sc_imo;
+
+		CARP_LOCK(cif);
+		callout_stop(&sc->sc_ad_tmo);
+		SC2IFP(sc)->if_flags &= ~IFF_UP;
+		SC2IFP(sc)->if_flags &= ~IFF_RUNNING;
+		sc->sc_vhid = -1;
+		in_delmulti(imo->imo_membership[--imo->imo_num_memberships]);
+		imo->imo_multicast_ifp = NULL;
+		TAILQ_REMOVE(&cif->vhif_vrs, sc, sc_list);
+		if (!--cif->vhif_nvrs) {
+			sc->sc_carpdev->if_carp = NULL;
+			CARP_LOCK_DESTROY(cif);
+			FREE(cif, M_IFADDR);
+		} else {
+			CARP_UNLOCK(cif);
+		}
+	}
+
+	return (error);
+}
+
+#ifdef INET6
+static int
+carp_set_addr6(struct carp_softc *sc, struct sockaddr_in6 *sin6)
+{
+	struct ifnet *ifp;
+	struct carp_if *cif;
+	struct in6_ifaddr *ia, *ia_if;
+	struct ip6_moptions *im6o = &sc->sc_im6o;
+	struct in6_multi_mship *imm;
+	struct in6_addr in6;
+	int own, error;
+
+	if (IN6_IS_ADDR_UNSPECIFIED(&sin6->sin6_addr)) {
+		if (!(SC2IFP(sc)->if_flags & IFF_UP))
+			carp_set_state(sc, INIT);
+		if (sc->sc_naddrs6)
+			SC2IFP(sc)->if_flags |= IFF_UP;
+		carp_setrun(sc, 0);
+		return (0);
+	}
+
+	/* we have to do it by hands to check we won't match on us */
+	ia_if = NULL; own = 0;
+	for (ia = in6_ifaddr; ia; ia = ia->ia_next) {
+		int i;
+
+		for (i = 0; i < 4; i++) {
+			if ((sin6->sin6_addr.s6_addr32[i] &
+			    ia->ia_prefixmask.sin6_addr.s6_addr32[i]) !=
+			    (ia->ia_addr.sin6_addr.s6_addr32[i] &
+			    ia->ia_prefixmask.sin6_addr.s6_addr32[i]))
+				break;
+		}
+		/* and, yeah, we need a multicast-capable iface too */
+		if (ia->ia_ifp != SC2IFP(sc) &&
+		    (ia->ia_ifp->if_flags & IFF_MULTICAST) &&
+		    (i == 4)) {
+			if (!ia_if)
+				ia_if = ia;
+			if (IN6_ARE_ADDR_EQUAL(&sin6->sin6_addr,
+			    &ia->ia_addr.sin6_addr))
+				own++;
+		}
+	}
+
+	if (!ia_if)
+		return (EADDRNOTAVAIL);
+	ia = ia_if;
+	ifp = ia->ia_ifp;
+
+	if (ifp == NULL || (ifp->if_flags & IFF_MULTICAST) == 0 ||
+	    (im6o->im6o_multicast_ifp && im6o->im6o_multicast_ifp != ifp))
+		return (EADDRNOTAVAIL);
+
+	if (!sc->sc_naddrs6) {
+		im6o->im6o_multicast_ifp = ifp;
+
+		/* join CARP multicast address */
+		bzero(&in6, sizeof(in6));
+		in6.s6_addr16[0] = htons(0xff02);
+		in6.s6_addr8[15] = 0x12;
+		if (in6_setscope(&in6, ifp, NULL) != 0)
+			goto cleanup;
+		if ((imm = in6_joingroup(ifp, &in6, &error)) == NULL)
+			goto cleanup;
+		LIST_INSERT_HEAD(&im6o->im6o_memberships, imm, i6mm_chain);
+
+		/* join solicited multicast address */
+		bzero(&in6, sizeof(in6));
+		in6.s6_addr16[0] = htons(0xff02);
+		in6.s6_addr32[1] = 0;
+		in6.s6_addr32[2] = htonl(1);
+		in6.s6_addr32[3] = sin6->sin6_addr.s6_addr32[3];
+		in6.s6_addr8[12] = 0xff;
+		if (in6_setscope(&in6, ifp, NULL) != 0)
+			goto cleanup;
+		if ((imm = in6_joingroup(ifp, &in6, &error)) == NULL)
+			goto cleanup;
+		LIST_INSERT_HEAD(&im6o->im6o_memberships, imm, i6mm_chain);
+	}
+
+	if (!ifp->if_carp) {
+		MALLOC(cif, struct carp_if *, sizeof(*cif), M_CARP,
+		    M_WAITOK|M_ZERO);
+		if (!cif) {
+			error = ENOBUFS;
+			goto cleanup;
+		}
+		if ((error = ifpromisc(ifp, 1))) {
+			FREE(cif, M_CARP);
+			goto cleanup;
+		}
+
+		CARP_LOCK_INIT(cif);
+		CARP_LOCK(cif);
+		cif->vhif_ifp = ifp;
+		TAILQ_INIT(&cif->vhif_vrs);
+		ifp->if_carp = cif;
+
+	} else {
+		struct carp_softc *vr;
+
+		cif = (struct carp_if *)ifp->if_carp;
+		CARP_LOCK(cif);
+		TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list)
+			if (vr != sc && vr->sc_vhid == sc->sc_vhid) {
+				CARP_UNLOCK(cif);
+				error = EINVAL;
+				goto cleanup;
+			}
+	}
+	sc->sc_ia6 = ia;
+	sc->sc_carpdev = ifp;
+
+	{ /* XXX prevent endless loop if already in queue */
+	struct carp_softc *vr, *after = NULL;
+	int myself = 0;
+	cif = (struct carp_if *)ifp->if_carp;
+	CARP_LOCK_ASSERT(cif);
+
+	TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list) {
+		if (vr == sc)
+			myself = 1;
+		if (vr->sc_vhid < sc->sc_vhid)
+			after = vr;
+	}
+
+	if (!myself) {
+		/* We're trying to keep things in order */
+		if (after == NULL) {
+			TAILQ_INSERT_TAIL(&cif->vhif_vrs, sc, sc_list);
+		} else {
+			TAILQ_INSERT_AFTER(&cif->vhif_vrs, after, sc, sc_list);
+		}
+		cif->vhif_nvrs++;
+	}
+	}
+
+	sc->sc_naddrs6++;
+	SC2IFP(sc)->if_flags |= IFF_UP;
+	if (own)
+		sc->sc_advskew = 0;
+	carp_sc_state_locked(sc);
+	carp_setrun(sc, 0);
+
+	CARP_UNLOCK(cif);
+
+	return (0);
+
+cleanup:
+	/* clean up multicast memberships */
+	if (!sc->sc_naddrs6) {
+		while (!LIST_EMPTY(&im6o->im6o_memberships)) {
+			imm = LIST_FIRST(&im6o->im6o_memberships);
+			LIST_REMOVE(imm, i6mm_chain);
+			in6_leavegroup(imm);
+		}
+	}
+	return (error);
+}
+
+static int
+carp_del_addr6(struct carp_softc *sc, struct sockaddr_in6 *sin6)
+{
+	int error = 0;
+
+	if (!--sc->sc_naddrs6) {
+		struct carp_if *cif = (struct carp_if *)sc->sc_carpdev->if_carp;
+		struct ip6_moptions *im6o = &sc->sc_im6o;
+
+		CARP_LOCK(cif);
+		callout_stop(&sc->sc_ad_tmo);
+		SC2IFP(sc)->if_flags &= ~IFF_UP;
+		SC2IFP(sc)->if_flags &= ~IFF_RUNNING;
+		sc->sc_vhid = -1;
+		while (!LIST_EMPTY(&im6o->im6o_memberships)) {
+			struct in6_multi_mship *imm =
+			    LIST_FIRST(&im6o->im6o_memberships);
+
+			LIST_REMOVE(imm, i6mm_chain);
+			in6_leavegroup(imm);
+		}
+		im6o->im6o_multicast_ifp = NULL;
+		TAILQ_REMOVE(&cif->vhif_vrs, sc, sc_list);
+		if (!--cif->vhif_nvrs) {
+			CARP_LOCK_DESTROY(cif);
+			sc->sc_carpdev->if_carp = NULL;
+			FREE(cif, M_IFADDR);
+		} else
+			CARP_UNLOCK(cif);
+	}
+
+	return (error);
+}
+#endif /* INET6 */
+
+static int
+carp_ioctl(struct ifnet *ifp, u_long cmd, caddr_t addr, struct ucred *creds)
+{
+	struct carp_softc *sc = ifp->if_softc, *vr;
+	struct carpreq carpr;
+	struct ifaddr *ifa;
+	struct ifreq *ifr;
+	struct ifaliasreq *ifra;
+	int locked = 0, error = 0;
+
+	ifa = (struct ifaddr *)addr;
+	ifra = (struct ifaliasreq *)addr;
+	ifr = (struct ifreq *)addr;
+
+
+	switch (cmd) {
+	case SIOCSIFADDR:
+		switch (ifa->ifa_addr->sa_family) {
+#ifdef INET
+		case AF_INET:
+			SC2IFP(sc)->if_flags |= IFF_UP;
+			bcopy(ifa->ifa_addr, ifa->ifa_dstaddr,
+			    sizeof(struct sockaddr));
+			error = carp_set_addr(sc, satosin(ifa->ifa_addr));
+			break;
+#endif /* INET */
+#ifdef INET6
+		case AF_INET6:
+			SC2IFP(sc)->if_flags |= IFF_UP;
+			error = carp_set_addr6(sc, satosin6(ifa->ifa_addr));
+			break;
+#endif /* INET6 */
+		default:
+			error = EAFNOSUPPORT;
+			break;
+		}
+		break;
+
+	case SIOCAIFADDR:
+		switch (ifa->ifa_addr->sa_family) {
+#ifdef INET
+		case AF_INET:
+			SC2IFP(sc)->if_flags |= IFF_UP;
+			bcopy(ifa->ifa_addr, ifa->ifa_dstaddr,
+			    sizeof(struct sockaddr));
+			error = carp_set_addr(sc, satosin(&ifra->ifra_addr));
+			break;
+#endif /* INET */
+#ifdef INET6
+		case AF_INET6:
+			SC2IFP(sc)->if_flags |= IFF_UP;
+			error = carp_set_addr6(sc, satosin6(&ifra->ifra_addr));
+			break;
+#endif /* INET6 */
+		default:
+			error = EAFNOSUPPORT;
+			break;
+		}
+		break;
+
+	case SIOCDIFADDR:
+		switch (ifa->ifa_addr->sa_family) {
+#ifdef INET
+		case AF_INET:
+			error = carp_del_addr(sc, satosin(&ifra->ifra_addr));
+			break;
+#endif /* INET */
+#ifdef INET6
+		case AF_INET6:
+			error = carp_del_addr6(sc, satosin6(&ifra->ifra_addr));
+			break;
+#endif /* INET6 */
+		default:
+			error = EAFNOSUPPORT;
+			break;
+		}
+		break;
+
+	case SIOCSIFFLAGS:
+		if (sc->sc_carpdev) {
+			locked = 1;
+			CARP_SCLOCK(sc);
+		}
+		if (sc->sc_state != INIT && !(ifr->ifr_flags & IFF_UP)) {
+ 			callout_stop(&sc->sc_ad_tmo);
+ 			callout_stop(&sc->sc_md_tmo);
+ 			callout_stop(&sc->sc_md6_tmo);
+			if (sc->sc_state == MASTER)
+				carp_send_ad_locked(sc);
+			carp_set_state(sc, INIT);
+			carp_setrun(sc, 0);
+		} else if (sc->sc_state == INIT && (ifr->ifr_flags & IFF_UP)) {
+			SC2IFP(sc)->if_flags |= IFF_UP;
+			carp_setrun(sc, 0);
+		}
+		break;
+
+	case SIOCSVH:
+		error = suser(curthread);
+		if (error)
+			break;
+		if ((error = copyin(ifr->ifr_data, &carpr, sizeof carpr)))
+			break;
+		error = 1;
+		if (sc->sc_carpdev) {
+			locked = 1;
+			CARP_SCLOCK(sc);
+		}
+		if (sc->sc_state != INIT && carpr.carpr_state != sc->sc_state) {
+			switch (carpr.carpr_state) {
+			case BACKUP:
+				callout_stop(&sc->sc_ad_tmo);
+				carp_set_state(sc, BACKUP);
+				carp_setrun(sc, 0);
+				carp_setroute(sc, RTM_DELETE);
+				break;
+			case MASTER:
+				carp_master_down_locked(sc);
+				break;
+			default:
+				break;
+			}
+		}
+		if (carpr.carpr_vhid > 0) {
+			if (carpr.carpr_vhid > 255) {
+				error = EINVAL;
+				break;
+			}
+			if (sc->sc_carpdev) {
+				struct carp_if *cif;
+				cif = (struct carp_if *)sc->sc_carpdev->if_carp;
+				TAILQ_FOREACH(vr, &cif->vhif_vrs, sc_list)
+					if (vr != sc &&
+					    vr->sc_vhid == carpr.carpr_vhid)
+						return EEXIST;
+			}
+			sc->sc_vhid = carpr.carpr_vhid;
+			IF_LLADDR(sc->sc_ifp)[0] = 0;
+			IF_LLADDR(sc->sc_ifp)[1] = 0;
+			IF_LLADDR(sc->sc_ifp)[2] = 0x5e;
+			IF_LLADDR(sc->sc_ifp)[3] = 0;
+			IF_LLADDR(sc->sc_ifp)[4] = 1;
+			IF_LLADDR(sc->sc_ifp)[5] = sc->sc_vhid;
+			error--;
+		}
+		if (carpr.carpr_advbase > 0 || carpr.carpr_advskew > 0) {
+			if (carpr.carpr_advskew >= 255) {
+				error = EINVAL;
+				break;
+			}
+			if (carpr.carpr_advbase > 255) {
+				error = EINVAL;
+				break;
+			}
+			sc->sc_advbase = carpr.carpr_advbase;
+			sc->sc_advskew = carpr.carpr_advskew;
+			error--;
+		}
+		bcopy(carpr.carpr_key, sc->sc_key, sizeof(sc->sc_key));
+		if (error > 0)
+			error = EINVAL;
+		else {
+			error = 0;
+			carp_setrun(sc, 0);
+		}
+		break;
+
+	case SIOCGVH:
+		/* XXX: lockless read */
+		bzero(&carpr, sizeof(carpr));
+		carpr.carpr_state = sc->sc_state;
+		carpr.carpr_vhid = sc->sc_vhid;
+		carpr.carpr_advbase = sc->sc_advbase;
+		carpr.carpr_advskew = sc->sc_advskew;
+		error = suser(curthread);
+		if (error == 0)
+			bcopy(sc->sc_key, carpr.carpr_key,
+			    sizeof(carpr.carpr_key));
+		error = copyout(&carpr, ifr->ifr_data, sizeof(carpr));
+		break;
+
+	default:
+		error = EINVAL;
+	}
+
+	if (locked)
+		CARP_SCUNLOCK(sc);
+
+	carp_hmac_prepare(sc);
+
+	return (error);
+}
+
+/*
+ * XXX: this is looutput. We should eventually use it from there.
+ */
+static int
+carp_looutput(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
+    struct rtentry *rt)
+{
+	u_int32_t af;
+
+	M_ASSERTPKTHDR(m); /* check if we have the packet header */
+
+	if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
+		m_freem(m);
+		return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
+			rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
+	}
+
+	ifp->if_opackets++;
+	ifp->if_obytes += m->m_pkthdr.len;
+
+	/* BPF writes need to be handled specially. */
+	if (dst->sa_family == AF_UNSPEC) {
+		bcopy(dst->sa_data, &af, sizeof(af));
+		dst->sa_family = af;
+	}
+
+#if 1	/* XXX */
+	switch (dst->sa_family) {
+	case AF_INET:
+	case AF_INET6:
+	case AF_IPX:
+	case AF_APPLETALK:
+		break;
+	default:
+		m_freem(m);
+		return (EAFNOSUPPORT);
+	}
+#endif
+	return(if_simloop(ifp, m, dst->sa_family, 0));
+}
+
+/*
+ * Start output on carp interface. This function should never be called.
+ */
+static void
+carp_start(struct ifnet *ifp)
+{
+#ifdef DEBUG
+	kprintf("%s: start called\n", ifp->if_xname);
+#endif
+}
+
+int
+carp_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *sa,
+    struct rtentry *rt)
+{
+	struct m_tag *mtag;
+	struct carp_softc *sc;
+	struct ifnet *carp_ifp;
+
+	if (!sa)
+		return (0);
+
+	switch (sa->sa_family) {
+#ifdef INET
+	case AF_INET:
+		break;
+#endif /* INET */
+#ifdef INET6
+	case AF_INET6:
+		break;
+#endif /* INET6 */
+	default:
+		return (0);
+	}
+
+	mtag = m_tag_find(m, PACKET_TAG_CARP, NULL);
+	if (mtag == NULL)
+		return (0);
+
+	bcopy(mtag + 1, &carp_ifp, sizeof(struct ifnet *));
+	sc = carp_ifp->if_softc;
+
+	/* Set the source MAC address to Virtual Router MAC Address */
+	switch (ifp->if_type) {
+	case IFT_ETHER:
+	case IFT_L2VLAN: {
+			struct ether_header *eh;
+
+			eh = mtod(m, struct ether_header *);
+			eh->ether_shost[0] = 0;
+			eh->ether_shost[1] = 0;
+			eh->ether_shost[2] = 0x5e;
+			eh->ether_shost[3] = 0;
+			eh->ether_shost[4] = 1;
+			eh->ether_shost[5] = sc->sc_vhid;
+		}
+		break;
+	case IFT_FDDI: {
+			struct fddi_header *fh;
+
+			fh = mtod(m, struct fddi_header *);
+			fh->fddi_shost[0] = 0;
+			fh->fddi_shost[1] = 0;
+			fh->fddi_shost[2] = 0x5e;
+			fh->fddi_shost[3] = 0;
+			fh->fddi_shost[4] = 1;
+			fh->fddi_shost[5] = sc->sc_vhid;
+		}
+		break;
+	case IFT_ISO88025: {
+ 			struct iso88025_header *th;
+ 			th = mtod(m, struct iso88025_header *);
+			th->iso88025_shost[0] = 3;
+			th->iso88025_shost[1] = 0;
+			th->iso88025_shost[2] = 0x40 >> (sc->sc_vhid - 1);
+			th->iso88025_shost[3] = 0x40000 >> (sc->sc_vhid - 1);
+			th->iso88025_shost[4] = 0;
+			th->iso88025_shost[5] = 0;
+		}
+		break;
+	default:
+		kprintf("%s: carp is not supported for this interface type\n",
+		    ifp->if_xname);
+		return (EOPNOTSUPP);
+	}
+
+	return (0);
+
+}
+
+static void
+carp_set_state(struct carp_softc *sc, int state)
+{
+
+	if (sc->sc_carpdev)
+		CARP_SCLOCK_ASSERT(sc);
+
+	if (sc->sc_state == state)
+		return;
+
+	sc->sc_state = state;
+	switch (state) {
+	case BACKUP:
+		SC2IFP(sc)->if_link_state = LINK_STATE_DOWN;
+		break;
+	case MASTER:
+		SC2IFP(sc)->if_link_state = LINK_STATE_UP;
+		break;
+	default:
+		SC2IFP(sc)->if_link_state = LINK_STATE_UNKNOWN;
+		break;
+	}
+	rt_ifmsg(SC2IFP(sc));
+}
+
+void
+carp_carpdev_state(void *v)
+{
+	struct carp_if *cif = v;
+
+	CARP_LOCK(cif);
+	carp_carpdev_state_locked(cif);
+	CARP_UNLOCK(cif);
+}
+
+static void
+carp_carpdev_state_locked(struct carp_if *cif)
+{
+	struct carp_softc *sc;
+
+	TAILQ_FOREACH(sc, &cif->vhif_vrs, sc_list)
+		carp_sc_state_locked(sc);
+}
+
+static void
+carp_sc_state_locked(struct carp_softc *sc)
+{
+	CARP_SCLOCK_ASSERT(sc);
+
+	if ( !(sc->sc_carpdev->if_flags & IFF_UP)) {
+		sc->sc_flags_backup = SC2IFP(sc)->if_flags;
+		SC2IFP(sc)->if_flags &= ~IFF_UP;
+		SC2IFP(sc)->if_flags &= ~IFF_RUNNING;
+		callout_stop(&sc->sc_ad_tmo);
+		callout_stop(&sc->sc_md_tmo);
+		callout_stop(&sc->sc_md6_tmo);
+		carp_set_state(sc, INIT);
+		carp_setrun(sc, 0);
+		if (!sc->sc_suppress) {
+			carp_suppress_preempt++;
+			if (carp_suppress_preempt == 1) {
+				CARP_SCUNLOCK(sc);
+				carp_send_ad_all();
+				CARP_SCLOCK(sc);
+			}
+		}
+		sc->sc_suppress = 1;
+	} else {
+		SC2IFP(sc)->if_flags |= sc->sc_flags_backup;
+		carp_set_state(sc, INIT);
+		carp_setrun(sc, 0);
+		if (sc->sc_suppress)
+			carp_suppress_preempt--;
+		sc->sc_suppress = 0;
+	}
+
+	return;
+}
+
+static int
+carp_modevent(module_t mod, int type, void *data)
+{
+	switch (type) {
+	case MOD_LOAD:
+		if_detach_event_tag = EVENTHANDLER_REGISTER(ifnet_departure_event,
+		    carp_ifdetach, NULL, EVENTHANDLER_PRI_ANY);
+		if (if_detach_event_tag == NULL)
+			return (ENOMEM);
+		
+		LIST_INIT(&carpif_list);
+		if_clone_attach(&carp_cloner);
+		break;
+
+	case MOD_UNLOAD:
+		EVENTHANDLER_DEREGISTER(ifnet_departure_event, if_detach_event_tag);
+		if_clone_detach(&carp_cloner);
+		break;
+
+	default:
+		return (EINVAL);
+	}
+
+	return (0);
+}
+
+static moduledata_t carp_mod = {
+	"carp",
+	carp_modevent,
+	0
+};
+
+DECLARE_MODULE(carp, carp_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
diff --git a/sys/netinet/ip_carp.h b/sys/netinet/ip_carp.h
new file mode 100644
index 0000000..5d3b6d1
--- /dev/null
+++ b/sys/netinet/ip_carp.h
@@ -0,0 +1,167 @@
+/*	$Id$	*/
+/*	from $FreeBSD: src/sys/netinet/ip_carp.h,v 1.3 2006/12/01 18:37:41 imp Exp $	*/
+/*	from $OpenBSD: ip_carp.h,v 1.8 2004/07/29 22:12:15 mcbride Exp $	*/
+
+/*
+ * Copyright (c) 2002 Michael Shalayeff. All rights reserved.
+ * Copyright (c) 2003 Ryan McBride. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR OR HIS RELATIVES BE LIABLE FOR ANY DIRECT,
+ * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF MIND, USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
+ * THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef _IP_CARP_H
+#define	_IP_CARP_H
+
+/*
+ * The CARP header layout is as follows:
+ *
+ *     0                   1                   2                   3
+ *     0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |Version| Type  | VirtualHostID |    AdvSkew    |    Auth Len   |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |   Reserved    |     AdvBase   |          Checksum             |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                         Counter (1)                           |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                         Counter (2)                           |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                        SHA-1 HMAC (1)                         |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                        SHA-1 HMAC (2)                         |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                        SHA-1 HMAC (3)                         |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                        SHA-1 HMAC (4)                         |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *    |                        SHA-1 HMAC (5)                         |
+ *    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+ *
+ */
+
+struct carp_header {
+#if BYTE_ORDER == LITTLE_ENDIAN
+	u_int8_t	carp_type:4,
+			carp_version:4;
+#endif
+#if BYTE_ORDER == BIG_ENDIAN
+	u_int8_t	carp_version:4,
+			carp_type:4;
+#endif
+	u_int8_t	carp_vhid;	/* virtual host id */
+	u_int8_t	carp_advskew;	/* advertisement skew */
+	u_int8_t	carp_authlen;   /* size of counter+md, 32bit chunks */
+	u_int8_t	carp_pad1;	/* reserved */
+	u_int8_t	carp_advbase;	/* advertisement interval */
+	u_int16_t	carp_cksum;
+	u_int32_t	carp_counter[2];
+	unsigned char	carp_md[20];	/* SHA1 HMAC */
+} __packed;
+
+#ifdef CTASSERT
+CTASSERT(sizeof(struct carp_header) == 36);
+#endif
+
+#define	CARP_DFLTTL		255
+
+/* carp_version */
+#define	CARP_VERSION		2
+
+/* carp_type */
+#define	CARP_ADVERTISEMENT	0x01
+
+#define	CARP_KEY_LEN		20	/* a sha1 hash of a passphrase */
+
+/* carp_advbase */
+#define	CARP_DFLTINTV		1
+
+/*
+ * Statistics.
+ */
+struct carpstats {
+	uint64_t	carps_ipackets;		/* total input packets, IPv4 */
+	uint64_t	carps_ipackets6;	/* total input packets, IPv6 */
+	uint64_t	carps_badif;		/* wrong interface */
+	uint64_t	carps_badttl;		/* TTL is not CARP_DFLTTL */
+	uint64_t	carps_hdrops;		/* packets shorter than hdr */
+	uint64_t	carps_badsum;		/* bad checksum */
+	uint64_t	carps_badver;		/* bad (incl unsupp) version */
+	uint64_t	carps_badlen;		/* data length does not match */
+	uint64_t	carps_badauth;		/* bad authentication */
+	uint64_t	carps_badvhid;		/* bad VHID */
+	uint64_t	carps_badaddrs;		/* bad address list */
+
+	uint64_t	carps_opackets;		/* total output packets, IPv4 */
+	uint64_t	carps_opackets6;	/* total output packets, IPv6 */
+	uint64_t	carps_onomem;		/* no memory for an mbuf */
+	uint64_t	carps_ostates;		/* total state updates sent */
+
+	uint64_t	carps_preempt;		/* if enabled, preemptions */
+};
+
+/*
+ * Configuration structure for SIOCSVH SIOCGVH
+ */
+struct carpreq {
+	int		carpr_state;
+#define	CARP_STATES	"INIT", "BACKUP", "MASTER"
+#define	CARP_MAXSTATE	2
+	int		carpr_vhid;
+	int		carpr_advskew;
+	int		carpr_advbase;
+	unsigned char	carpr_key[CARP_KEY_LEN];
+};
+#define	SIOCSVH	_IOWR('i', 245, struct ifreq)
+#define	SIOCGVH	_IOWR('i', 246, struct ifreq)
+
+/*
+ * Names for CARP sysctl objects
+ */
+#define	CARPCTL_ALLOW		1	/* accept incoming CARP packets */
+#define	CARPCTL_PREEMPT		2	/* high-pri backup preemption mode */
+#define	CARPCTL_LOG		3	/* log bad packets */
+#define	CARPCTL_STATS		4	/* statistics (read-only) */
+#define	CARPCTL_ARPBALANCE	5	/* balance arp responses */
+#define	CARPCTL_MAXID		6
+
+#define	CARPCTL_NAMES { \
+	{ 0, 0 }, \
+	{ "allow", CTLTYPE_INT }, \
+	{ "preempt", CTLTYPE_INT }, \
+	{ "log", CTLTYPE_INT }, \
+	{ "stats", CTLTYPE_STRUCT }, \
+	{ "arpbalance", CTLTYPE_INT }, \
+}
+
+#ifdef _KERNEL
+void		 carp_carpdev_state(void *);
+void		 carp_input (struct mbuf *, int);
+int		 carp6_input (struct mbuf **, int *, int);
+int		 carp_output (struct ifnet *, struct mbuf *, struct sockaddr *,
+		     struct rtentry *);
+int		 carp_iamatch (void *, struct in_ifaddr *, struct in_addr *,
+		     u_int8_t **);
+struct ifaddr	*carp_iamatch6(void *, struct in6_addr *);
+void		*carp_macmatch6(void *, struct mbuf *, const struct in6_addr *);
+struct	ifnet	*carp_forus (void *, void *);
+#endif
+#endif /* _IP_CARP_H */
diff --git a/sys/netinet/ip_var.h b/sys/netinet/ip_var.h
index 6c2809f..31da470 100644
--- a/sys/netinet/ip_var.h
+++ b/sys/netinet/ip_var.h
@@ -115,6 +115,7 @@ struct ip_moptions {
 	u_char	imo_multicast_ttl;	/* TTL for outgoing multicasts */
 	u_char	imo_multicast_loop;	/* 1 => hear sends if a member */
 	u_short	imo_num_memberships;	/* no. memberships this socket */
+	u_short imo_max_memberships;    /* max memberships this socket */
 	struct	in_multi *imo_membership[IP_MAX_MEMBERSHIPS];
 	u_long	imo_multicast_vif;	/* vif num outgoing multicasts */
 };
diff --git a/sys/netinet6/in6.c b/sys/netinet6/in6.c
index ae76439..f84087b 100644
--- a/sys/netinet6/in6.c
+++ b/sys/netinet6/in6.c
@@ -231,7 +231,7 @@ done:
  * rely on the cloning mechanism from the corresponding interface route
  * any more.
  */
-static void
+void
 in6_ifaddloop(struct ifaddr *ifa)
 {
 	struct rtentry *rt;
@@ -249,7 +249,7 @@ in6_ifaddloop(struct ifaddr *ifa)
  * Remove loopback rtentry of ownaddr generated by in6_ifaddloop(),
  * if it exists.
  */
-static void
+void
 in6_ifremloop(struct ifaddr *ifa)
 {
 	struct in6_ifaddr *ia;
@@ -1614,6 +1614,39 @@ in6_ifinit(struct ifnet *ifp, struct in6
 	return (error);
 }
 
+struct in6_multi_mship *
+in6_joingroup(ifp, addr, errorp)
+       struct ifnet *ifp;
+       struct in6_addr *addr;
+       int *errorp;
+{
+       struct in6_multi_mship *imm;
+
+       imm = kmalloc(sizeof(*imm), M_IPMADDR, M_NOWAIT);
+       if (!imm) {
+               *errorp = ENOBUFS;
+               return NULL;
+       }
+       imm->i6mm_maddr = in6_addmulti(addr, ifp, errorp);
+       if (!imm->i6mm_maddr) {
+               /* *errorp is alrady set */
+               kfree(imm, M_IPMADDR);
+               return NULL;
+       }
+       return imm;
+}
+
+int
+in6_leavegroup(imm)
+       struct in6_multi_mship *imm;
+{
+
+       if (imm->i6mm_maddr)
+               in6_delmulti(imm->i6mm_maddr);
+       kfree(imm,  M_IPMADDR);
+       return 0;
+}
+
 /*
  * Add an address to the list of IP6 multicast addresses for a
  * given interface.
diff --git a/sys/netinet6/in6_ifattach.c b/sys/netinet6/in6_ifattach.c
index 1e0bd15..94833c6 100644
--- a/sys/netinet6/in6_ifattach.c
+++ b/sys/netinet6/in6_ifattach.c
@@ -714,6 +714,7 @@ in6_ifattach(struct ifnet *ifp,
 #endif
 	case IFT_PFLOG:
 	case IFT_PFSYNC:
+	case IFT_CARP:
 		return;
 	}
 
diff --git a/sys/netinet6/in6_proto.c b/sys/netinet6/in6_proto.c
index 1434cca..f2b430b 100644
--- a/sys/netinet6/in6_proto.c
+++ b/sys/netinet6/in6_proto.c
@@ -69,6 +69,7 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
+#include "opt_carp.h"
 
 #include <sys/param.h>
 #include <sys/socket.h>
@@ -140,6 +141,11 @@
 
 #include <net/net_osdep.h>
 
+#ifdef CARP
+#include <netinet/ip_carp.h>
+#endif
+
+
 /*
  * TCP/IP protocol family: IP6, ICMP6, UDP, TCP.
  */
@@ -247,6 +253,15 @@ struct ip6protosw inet6sw[] = {
   0,            0,              0,              0,
   &rip6_usrreqs
 },
+#ifdef CARP
+{ SOCK_RAW,    &inet6domain,   IPPROTO_CARP,   PR_ATOMIC|PR_ADDR,
+  carp6_input, rip6_output,    0,              rip6_ctloutput,
+  0,
+  0,            0,              0,              0,
+  &rip6_usrreqs
+},
+#endif /* CARP */
+
 /* raw wildcard */
 { SOCK_RAW,	&inet6domain,	0,		PR_ATOMIC|PR_ADDR,
   rip6_input,	rip6_output,	0,		rip6_ctloutput,
diff --git a/sys/netinet6/in6_var.h b/sys/netinet6/in6_var.h
index 6420634..cbfe2cb 100644
--- a/sys/netinet6/in6_var.h
+++ b/sys/netinet6/in6_var.h
@@ -585,6 +585,9 @@ do { \
 struct	in6_multi *in6_addmulti (struct in6_addr *, struct ifnet *,
 				     int *);
 void	in6_delmulti (struct in6_multi *);
+struct	in6_multi_mship *in6_joingroup(struct ifnet *, struct in6_addr *, int *);
+int	in6_leavegroup(struct in6_multi_mship *);
+
 extern int in6_ifindex2scopeid (int);
 extern int in6_mask2len (struct in6_addr *, u_char *);
 extern void in6_len2mask (struct in6_addr *, int);
@@ -615,6 +618,8 @@ int	in6_prefix_ioctl (struct socket *so,
 int	in6_prefix_add_ifid (int iilen, struct in6_ifaddr *ia);
 void	in6_prefix_remove_ifid (int iilen, struct in6_ifaddr *ia);
 void	in6_purgeprefix (struct ifnet *);
+void	in6_ifremloop(struct ifaddr *);
+void	in6_ifaddloop(struct ifaddr *);
 
 int	in6_is_addr_deprecated (struct sockaddr_in6 *);
 struct inpcb;
diff --git a/sys/netinet6/nd6.c b/sys/netinet6/nd6.c
index 801ec0c..e295fa5 100644
--- a/sys/netinet6/nd6.c
+++ b/sys/netinet6/nd6.c
@@ -1994,6 +1994,9 @@ nd6_need_cache(struct ifnet *ifp)
 #ifdef IFT_IEEE80211
 	case IFT_IEEE80211:
 #endif
+#ifdef IFT_CARP
+	case IFT_CARP:
+#endif
 	case IFT_GIF:		/* XXX need more cases? */
 		return (1);
 	default:
diff --git a/sys/netinet6/nd6_nbr.c b/sys/netinet6/nd6_nbr.c
index 04f051b..4c70301 100644
--- a/sys/netinet6/nd6_nbr.c
+++ b/sys/netinet6/nd6_nbr.c
@@ -34,6 +34,7 @@
 #include "opt_inet.h"
 #include "opt_inet6.h"
 #include "opt_ipsec.h"
+#include "opt_carp.h"
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -71,6 +72,11 @@
 
 #include <net/net_osdep.h>
 
+#ifdef CARP
+#include <netinet/ip_carp.h>
+#endif
+
+
 #define SDL(s) ((struct sockaddr_dl *)s)
 
 struct dadq;
@@ -102,7 +108,7 @@ nd6_ns_input(struct mbuf *m, int off, in
 	struct in6_addr taddr6;
 	struct in6_addr myaddr6;
 	char *lladdr = NULL;
-	struct ifaddr *ifa;
+	struct ifaddr *ifa = NULL;
 	int lladdrlen = 0;
 	int anycast = 0, proxy = 0, tentative = 0;
 	int tlladdr;
@@ -201,7 +207,14 @@ nd6_ns_input(struct mbuf *m, int off, in
 	 * (3) "tentative" address on which DAD is being performed.
 	 */
 	/* (1) and (3) check. */
+#ifdef CARP
+       if (ifp->if_carp)
+               ifa = carp_iamatch6(ifp->if_carp, &taddr6);
+       if (!ifa)
+               ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
+#else
 	ifa = (struct ifaddr *)in6ifa_ifpwithaddr(ifp, &taddr6);
+#endif
 
 	/* (2) check. */
 	if (!ifa) {
@@ -895,9 +908,16 @@ nd6_na_output(struct ifnet *ifp, const s
 		 * lladdr in sdl0.  If we are not proxying (sending NA for
 		 * my address) use lladdr configured for the interface.
 		 */
-		if (sdl0 == NULL)
+		if (sdl0 == NULL) {
+#ifdef CARP
+			if (ifp->if_carp)
+				mac = carp_macmatch6(ifp->if_carp, m, taddr6);
+			if (mac == NULL)
+				mac = nd6_ifptomac(ifp);
+#else
 			mac = nd6_ifptomac(ifp);
-		else if (sdl0->sa_family == AF_LINK) {
+#endif
+		} else if (sdl0->sa_family == AF_LINK) {
 			struct sockaddr_dl *sdl;
 			sdl = (struct sockaddr_dl *)sdl0;
 			if (sdl->sdl_alen == ifp->if_addrlen)
@@ -949,6 +969,9 @@ nd6_ifptomac(struct ifnet *ifp)
 #ifdef IFT_IEEE80211
 	case IFT_IEEE80211:
 #endif
+#ifdef IFT_CARP
+	case IFT_CARP:
+#endif
 		return ((caddr_t)(ifp + 1));
 		break;
 	default:
diff --git a/sys/netinet6/scope6.c b/sys/netinet6/scope6.c
index 96b0891..2957c58 100644
--- a/sys/netinet6/scope6.c
+++ b/sys/netinet6/scope6.c
@@ -296,3 +296,76 @@ scope6_addr2default(struct in6_addr *add
 
 	return (sid_default.s6id_list[in6_addrscope(addr)]);
 }
+
+/*
+ * Determine the appropriate scope zone ID for in6 and ifp.  If ret_id is
+ * non NULL, it is set to the zone ID.  If the zone ID needs to be embedded
+  * in the in6_addr structure, in6 will be modified.
+ */
+int
+in6_setscope(struct in6_addr *in6, struct ifnet *ifp, u_int32_t *ret_id)
+{
+	int scope;
+	u_int32_t zoneid = 0;
+	struct scope6_id *sid;
+
+	lwkt_serialize_enter(ifp->if_serializer);
+
+	sid = SID(ifp);
+
+#ifdef DIAGNOSTIC
+	if (sid == NULL) { /* should not happen */
+		panic("in6_setscope: scope array is NULL");
+		/* NOTREACHED */
+	}
+#endif
+
+	/*
+	 * special case: the loopback address can only belong to a loopback
+	 * interface.
+	 */
+	if (IN6_IS_ADDR_LOOPBACK(in6)) {
+		if (!(ifp->if_flags & IFF_LOOPBACK)) {
+			lwkt_serialize_exit(ifp->if_serializer);
+			return (EINVAL);
+		} else {
+			if (ret_id != NULL)
+				*ret_id = 0; /* there's no ambiguity */
+			lwkt_serialize_exit(ifp->if_serializer);
+			return (0);
+		}
+	}
+
+	scope = in6_addrscope(in6);
+
+	switch (scope) {
+	case IPV6_ADDR_SCOPE_NODELOCAL: /* should be interface index */
+		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_NODELOCAL];
+		break;
+
+	case IPV6_ADDR_SCOPE_LINKLOCAL:
+		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_LINKLOCAL];
+		break;
+
+	case IPV6_ADDR_SCOPE_SITELOCAL:
+		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_SITELOCAL];
+		break;
+
+	case IPV6_ADDR_SCOPE_ORGLOCAL:
+		zoneid = sid->s6id_list[IPV6_ADDR_SCOPE_ORGLOCAL];
+		break;
+
+	default:
+		zoneid = 0;     /* XXX: treat as global. */
+		break;
+	}
+	lwkt_serialize_exit(ifp->if_serializer);
+
+	if (ret_id != NULL)
+		*ret_id = zoneid;
+
+	if (IN6_IS_SCOPE_LINKLOCAL(in6) || IN6_IS_ADDR_MC_NODELOCAL(in6) )
+		in6->s6_addr16[1] = htons(zoneid & 0xffff); /* XXX */
+
+	return (0);
+}
diff --git a/sys/netinet6/scope6_var.h b/sys/netinet6/scope6_var.h
index 57c84c4..62427e3 100644
--- a/sys/netinet6/scope6_var.h
+++ b/sys/netinet6/scope6_var.h
@@ -65,6 +65,7 @@ void	scope6_setdefault (struct ifnet *);
 int	scope6_get_default (struct scope6_id *);
 u_int32_t scope6_in6_addrscope (struct in6_addr *);
 u_int32_t scope6_addr2default (struct in6_addr *);
+int	in6_setscope __P((struct in6_addr *, struct ifnet *, u_int32_t *));
 
 #endif /* _KERNEL */
 
diff --git a/sys/sys/mbuf.h b/sys/sys/mbuf.h
index 6391553..0774545 100644
--- a/sys/sys/mbuf.h
+++ b/sys/sys/mbuf.h
@@ -560,6 +560,7 @@ m_getb(int len, int how, int type, int f
 /* struct ip6aux */
 #define	PACKET_TAG_IPFW_DIVERT			9 /* divert info */
 /* uint16_t */
+#define	PACKET_TAG_CARP                         28 /* CARP info */
 
 /*
  * As a temporary and low impact solution to replace the even uglier
diff --git a/usr.bin/netstat/inet.c b/usr.bin/netstat/inet.c
index 1158082..47e76c7 100644
--- a/usr.bin/net7 @@
 #include <netinet/in.h>
 #include <netinet/in_systm.h>
 #include <netinet/ip.h>
+#include <netinet/ip_carp.h>
 #ifdef INET6
 #include <netinet/ip6.h>
 #endif /* INET6 */
@@ -584,6 +585,50 @@ udp_stats(u_long off __unused, char *nam
 #undef p1a
 }
 
+/* 
+ * Dump CARP statistics structure.
+ */
+void
+carp_stats(u_long off, const char *name, int af1 __unused)
+{
+       struct carpstats carpstat, zerostat;
+       size_t len = sizeof(struct carpstats);
+
+       if (zflag)
+               memset(&zerostat, 0, len);
+       if (sysctlbyname("net.inet.carp.stats", &carpstat, &len,
+           zflag ? &zerostat : NULL, zflag ? len : 0) < 0) {
+               warn("sysctl: net.inet.carp.stats");
+               return;
+       }
+
+       printf("%s:\n", name);
+
+#define p(f, m) if (carpstat.f || sflag <= 1) \
+       printf(m, (unsigned long long)carpstat.f, plural((int)carpstat.f))
+#define p2(f, m) if (carpstat.f || sflag <= 1) \
+       printf(m, (unsigned long long)carpstat.f)
+
+       p(carps_ipackets, "\t%llu packet%s received (IPv4)\n");
+       p(carps_ipackets6, "\t%llu packet%s received (IPv6)\n");
+       p(carps_badttl, "\t\t%llu packet%s discarded for wrong TTL\n");
+       p(carps_hdrops, "\t\t%llu packet%s shorter than header\n");
+       p(carps_badsum, "\t\t%llu discarded for bad checksum%s\n");
+       p(carps_badver, "\t\t%llu discarded packet%s with a bad version\n");
+       p2(carps_badlen, "\t\t%llu discarded because packet too short\n");
+       p2(carps_badauth, "\t\t%llu discarded for bad authentication\n");
+       p2(carps_badvhid, "\t\t%llu discarded for bad vhid\n");
+       p2(carps_badaddrs, "\t\t%llu discarded because of a bad address list\n");
+       p(carps_opackets, "\t%llu packet%s sent (IPv4)\n");
+       p(carps_opackets6, "\t%llu packet%s sent (IPv6)\n");
+       p2(carps_onomem, "\t\t%llu send failed due to mbuf memory error\n");
+#if notyet
+       p(carps_ostates, "\t\t%s state update%s sent\n");
+#endif
+#undef p
+#undef p2
+}
+
 /*
  * Dump IP statistics structure.
  */
diff --git a/usr.bin/netstat/main.c b/usr.bin/netstat/main.c
index b487811..2004d93 100644
--- a/usr.bin/netstat/main.c
+++ b/usr.bin/netstat/main.c
@@ -148,6 +148,8 @@ static struct nlist nl[] = {
 	{ "_rttrash" },
 #define	N_NCPUS		43
 	{ "_ncpus" },
+#define	N_CARPSTAT	44
+	{ "_carpstats" },
 	{ "" },
 };
 
@@ -179,6 +181,8 @@ struct protox {
 	{ -1,		N_IPSECSTAT,	1,	0,
 	  ipsec_stats,	NULL,		"ipsec",	0},
 #endif
+        { -1,           N_CARPSTAT,     1,      0,
+          carp_stats,   NULL,           "carp",         0},
 	{ -1,		-1,		0,	0,
 	  0,		NULL,		0 }
 };
diff --git a/usr.bin/netstat/netstat.h b/usr.bin/netstat/netstat.h
index f0329cd..b7cd79e 100644
--- a/usr.bin/netstat/netstat.h
+++ b/usr.bin/netstat/netstat.h
@@ -73,6 +73,7 @@ void	ip_stats (u_long, char *, int);
 void	icmp_stats (u_long, char *, int);
 void	igmp_stats (u_long, char *, int);
 void	pim_stats (u_long, char *, int);
+void   carp_stats (u_long, const char *, int);
 #ifdef IPSEC
 void	ipsec_stats (u_long, char *, int);
 #endif




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