Add CARP (Common Address Redundancy Protocol), which allows multiple

hosts to share an IP address, providing high availability and load
balancing.

Original work on CARP done by Michael Shalayeff, with many
additions by Marco Pfatschbacher and Ryan McBride.

FreeBSD port done solely by Max Laier.

Patch by:	mlaier
Obtained from:	OpenBSD (mickey, mcbride)

1 files changed, 34 insertions, 5 deletions

diff --git a/sys/netinet/if_ether.c b/sys/netinet/if_ether.c
index 2f1c037..1bc1d06 100644
--- a/sys/netinet/if_ether.c
+++ b/sys/netinet/if_ether.c
@@ -39,6 +39,7 @@
 #include "opt_inet.h"
 #include "opt_bdg.h"
 #include "opt_mac.h"
+#include "opt_carp.h"
 
 #include <sys/param.h>
 #include <sys/kernel.h>
@@ -67,6 +68,10 @@
 #include <net/if_arc.h>
 #include <net/iso88025.h>
 
+#ifdef DEV_CARP
+#include <netinet/ip_carp.h>
+#endif
+
 #define SIN(s) ((struct sockaddr_in *)s)
 #define SDL(s) ((struct sockaddr_dl *)s)
 
@@ -545,6 +550,7 @@ in_arpinput(m)
 	struct sockaddr_dl *sdl;
 	struct sockaddr sa;
 	struct in_addr isaddr, itaddr, myaddr;
+	u_int8_t *enaddr = NULL;
 	int op, rif_len;
 	int req_len;
 
@@ -563,10 +569,18 @@ in_arpinput(m)
 	 * For a bridge, we want to check the address irrespective
 	 * of the receive interface. (This will change slightly
 	 * when we have clusters of interfaces).
+	 * 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!
 	 */
 	LIST_FOREACH(ia, INADDR_HASH(itaddr.s_addr), ia_hash)
-		if ((do_bridge || (ia->ia_ifp == ifp)) &&
-		    itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
+		if ((do_bridge || (ia->ia_ifp == ifp)
+#ifdef DEV_CARP
+		    || (ifp->if_carp
+		    && carp_iamatch(ifp->if_carp, ia, &isaddr, &enaddr))
+#endif
+		    ) && itaddr.s_addr == ia->ia_addr.sin_addr.s_addr)
 			goto match;
 	LIST_FOREACH(ia, INADDR_HASH(isaddr.s_addr), ia_hash)
 		if ((do_bridge || (ia->ia_ifp == ifp)) &&
@@ -587,8 +601,10 @@ in_arpinput(m)
 	if (!do_bridge || (ia = TAILQ_FIRST(&in_ifaddrhead)) == NULL)
 		goto drop;
 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))
 		goto drop;	/* it's from me, ignore it. */
 	if (!bcmp(ar_sha(ah), ifp->if_broadcastaddr, ifp->if_addrlen)) {
 		log(LOG_ERR,
@@ -711,7 +727,7 @@ reply:
 	if (itaddr.s_addr == myaddr.s_addr) {
 		/* I am the target */
 		(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
-		(void)memcpy(ar_sha(ah), IF_LLADDR(ifp), ah->ar_hln);
+		(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
 	} else {
 		la = arplookup(itaddr.s_addr, 0, SIN_PROXY);
 		if (la == NULL) {
@@ -738,7 +754,7 @@ reply:
 				goto drop;
 			}
 			(void)memcpy(ar_tha(ah), ar_sha(ah), ah->ar_hln);
-			(void)memcpy(ar_sha(ah), IF_LLADDR(ifp), ah->ar_hln);
+			(void)memcpy(ar_sha(ah), enaddr, ah->ar_hln);
 			rtfree(rt);
 
 			/*
@@ -880,6 +896,19 @@ arp_ifinit(ifp, ifa)
 	ifa->ifa_flags |= RTF_CLONING;
 }
 
+void
+arp_ifinit2(ifp, ifa, enaddr)
+	struct ifnet *ifp;
+	struct ifaddr *ifa;
+	u_char *enaddr;
+{
+	if (ntohl(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)
 {