[IPV6] ADDRCONF: Mobile IPv6 Home Address support.

IFA_F_HOMEADDRESS is introduced for Mobile IPv6 Home Addresses on
Mobile Node.

The IFA_F_HOMEADDRESS flag should be set for Mobile IPv6 Home
Addresses for 2 purposes. 1) We need to check this on receipt of
Type 2 Routing Header (RFC3775 Secion 6.4), 2) We prefer Home
Address(es) in source address selection (RFC3484 Section 5 Rule 4).

Signed-off-by: Noriaki TAKAMIYA <takamiya@po.ntts.co.jp>
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/if_addr.h

@@ -39,6 +39,7 @@ enum
 #define IFA_F_TEMPORARY		IFA_F_SECONDARY
 
 #define	IFA_F_NODAD		0x02
+#define	IFA_F_HOMEADDRESS	0x10
 #define IFA_F_DEPRECATED	0x20
 #define IFA_F_TENTATIVE		0x40
 #define IFA_F_PERMANENT		0x80

include/net/addrconf.h

@@ -61,12 +61,8 @@ extern int			addrconf_set_dstaddr(void __user *arg);
 extern int			ipv6_chk_addr(struct in6_addr *addr,
 					      struct net_device *dev,
 					      int strict);
-/* XXX: this is a placeholder till addrconf supports */
 #ifdef CONFIG_IPV6_MIP6
-static inline int ipv6_chk_home_addr(struct in6_addr *addr)
-{
-	return 0;
-}
+extern int			ipv6_chk_home_addr(struct in6_addr *addr);
 #endif
 extern struct inet6_ifaddr *	ipv6_get_ifaddr(struct in6_addr *addr,
 						struct net_device *dev,

net/ipv6/addrconf.c

@@ -1038,9 +1038,27 @@ int ipv6_dev_get_saddr(struct net_device *daddr_dev,
 					continue;
 			}
 
-			/* Rule 4: Prefer home address -- not implemented yet */
+			/* Rule 4: Prefer home address */
+#ifdef CONFIG_IPV6_MIP6
+			if (hiscore.rule < 4) {
+				if (ifa_result->flags & IFA_F_HOMEADDRESS)
+					hiscore.attrs |= IPV6_SADDR_SCORE_HOA;
+				hiscore.rule++;
+			}
+			if (ifa->flags & IFA_F_HOMEADDRESS) {
+				score.attrs |= IPV6_SADDR_SCORE_HOA;
+				if (!(ifa_result->flags & IFA_F_HOMEADDRESS)) {
+					score.rule = 4;
+					goto record_it;
+				}
+			} else {
+				if (hiscore.attrs & IPV6_SADDR_SCORE_HOA)
+					continue;
+			}
+#else
 			if (hiscore.rule < 4)
 				hiscore.rule++;
+#endif
 
 			/* Rule 5: Prefer outgoing interface */
 			if (hiscore.rule < 5) {
@@ -2759,6 +2777,26 @@ void if6_proc_exit(void)
 }
 #endif	/* CONFIG_PROC_FS */
 
+#ifdef CONFIG_IPV6_MIP6
+/* Check if address is a home address configured on any interface. */
+int ipv6_chk_home_addr(struct in6_addr *addr)
+{
+	int ret = 0;
+	struct inet6_ifaddr * ifp;
+	u8 hash = ipv6_addr_hash(addr);
+	read_lock_bh(&addrconf_hash_lock);
+	for (ifp = inet6_addr_lst[hash]; ifp; ifp = ifp->lst_next) {
+		if (ipv6_addr_cmp(&ifp->addr, addr) == 0 &&
+		    (ifp->flags & IFA_F_HOMEADDRESS)) {
+			ret = 1;
+			break;
+		}
+	}
+	read_unlock_bh(&addrconf_hash_lock);
+	return ret;
+}
+#endif
+
 /*
  *	Periodic address status verification
  */
@@ -2930,7 +2968,7 @@ static int inet6_addr_modify(struct inet6_ifaddr *ifp, u8 ifa_flags,
 		prefered_lft = 0x7FFFFFFF/HZ;
 
 	spin_lock_bh(&ifp->lock);
-	ifp->flags = (ifp->flags & ~(IFA_F_DEPRECATED | IFA_F_PERMANENT | IFA_F_NODAD)) | ifa_flags;
+	ifp->flags = (ifp->flags & ~(IFA_F_DEPRECATED | IFA_F_PERMANENT | IFA_F_NODAD | IFA_F_HOMEADDRESS)) | ifa_flags;
 	ifp->tstamp = jiffies;
 	ifp->valid_lft = valid_lft;
 	ifp->prefered_lft = prefered_lft;
@@ -2981,7 +3019,7 @@ inet6_rtm_newaddr(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
 		return -ENODEV;
 
 	/* We ignore other flags so far. */
-	ifa_flags = ifm->ifa_flags & IFA_F_NODAD;
+	ifa_flags = ifm->ifa_flags & (IFA_F_NODAD | IFA_F_HOMEADDRESS);
 
 	ifa = ipv6_get_ifaddr(pfx, dev, 1);
 	if (ifa == NULL) {