RFC3484 compliant source address selection

Hello.

David, this is what I promised before.

Please pull the following changesets, which implement
the source address selection algorythm described in RFC3484; e.g.: 

 - avoid using daprecated address
 - prefer address in appropriate scope / on appropriate interface
 - (minimum support of) matching label
 - prefer longest matching address

Changesets are available at:
	git://git.skbuff.net/gitroot/yoshfuji/linux-2.6.14+git+saddrselect-20051107.git

I'd like to give special thanks to Perry Lorier and Ian McDonald.
Thank you again.

===================================================================

HEADLINES
---------
 [IPV6]: Put addr_diff() into common header for future use.
 [IPV6]: Make ipv6_addr_type() more generic so that we can use it for source address selection.
 [IPV6]: RFC3484 compliant source address selection

DIFFSTAT
--------
 include/net/ipv6.h   |   67 +++++++-
 net/ipv6/addrconf.c  |  430 +++++++++++++++++++++++++++++++++-----------------
 net/ipv6/ip6_fib.c   |   54 ------
 net/ipv6/ipv6_syms.c |    2 
 4 files changed, 352 insertions(+), 201 deletions(-)

CHANGELOGS
----------

[IPV6]: Put addr_diff() into common header for future use.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 65ec866..98661fa 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -341,6 +341,54 @@ static inline int ipv6_addr_any(const st
 }
 
 /*
+ * find the first different bit between two addresses
+ * length of address must be a multiple of 32bits
+ */
+static inline int __ipv6_addr_diff(const void *token1, const void *token2, int addrlen)
+{
+	const __u32 *a1 = token1, *a2 = token2;
+	int i;
+
+	addrlen >>= 2;
+
+	for (i = 0; i < addrlen; i++) {
+		__u32 xb = a1[i] ^ a2[i];
+		if (xb) {
+			int j = 31;
+
+			xb = ntohl(xb);
+			while ((xb & (1 << j)) == 0)
+				j--;
+
+			return (i * 32 + 31 - j);
+		}
+	}
+
+	/*
+	 *	we should *never* get to this point since that 
+	 *	would mean the addrs are equal
+	 *
+	 *	However, we do get to it 8) And exacly, when
+	 *	addresses are equal 8)
+	 *
+	 *	ip route add 1111::/128 via ...
+	 *	ip route add 1111::/64 via ...
+	 *	and we are here.
+	 *
+	 *	Ideally, this function should stop comparison
+	 *	at prefix length. It does not, but it is still OK,
+	 *	if returned value is greater than prefix length.
+	 *					--ANK (980803)
+	 */
+	return (addrlen << 5);
+}
+
+static inline int ipv6_addr_diff(const struct in6_addr *a1, const struct in6_addr *a2)
+{
+	return __ipv6_addr_diff(a1, a2, sizeof(struct in6_addr));
+}
+
+/*
  *	Prototypes exported by ipv6
  */
 
diff --git a/net/ipv6/ip6_fib.c b/net/ipv6/ip6_fib.c
index 4fcc5a7..1bf6d9a 100644
--- a/net/ipv6/ip6_fib.c
+++ b/net/ipv6/ip6_fib.c
@@ -127,56 +127,6 @@ static __inline__ int addr_bit_set(void 
 	return htonl(1 << ((~fn_bit)&0x1F)) & addr[fn_bit>>5];
 }
 
-/*
- *	find the first different bit between two addresses
- *	length of address must be a multiple of 32bits
- */
-
-static __inline__ int addr_diff(void *token1, void *token2, int addrlen)
-{
-	__u32 *a1 = token1;
-	__u32 *a2 = token2;
-	int i;
-
-	addrlen >>= 2;
-
-	for (i = 0; i < addrlen; i++) {
-		__u32 xb;
-
-		xb = a1[i] ^ a2[i];
-
-		if (xb) {
-			int j = 31;
-
-			xb = ntohl(xb);
-
-			while ((xb & (1 << j)) == 0)
-				j--;
-
-			return (i * 32 + 31 - j);
-		}
-	}
-
-	/*
-	 *	we should *never* get to this point since that 
-	 *	would mean the addrs are equal
-	 *
-	 *	However, we do get to it 8) And exacly, when
-	 *	addresses are equal 8)
-	 *
-	 *	ip route add 1111::/128 via ...
-	 *	ip route add 1111::/64 via ...
-	 *	and we are here.
-	 *
-	 *	Ideally, this function should stop comparison
-	 *	at prefix length. It does not, but it is still OK,
-	 *	if returned value is greater than prefix length.
-	 *					--ANK (980803)
-	 */
-
-	return addrlen<<5;
-}
-
 static __inline__ struct fib6_node * node_alloc(void)
 {
 	struct fib6_node *fn;
@@ -296,11 +246,11 @@ insert_above:
 
 	/* find 1st bit in difference between the 2 addrs.
 
-	   See comment in addr_diff: bit may be an invalid value,
+	   See comment in __ipv6_addr_diff: bit may be an invalid value,
 	   but if it is >= plen, the value is ignored in any case.
 	 */
 	
-	bit = addr_diff(addr, &key->addr, addrlen);
+	bit = __ipv6_addr_diff(addr, &key->addr, addrlen);
 
 	/* 
 	 *		(intermediate)[in]	
---
[IPV6]: Make ipv6_addr_type() more generic so that we can use it for source address selection.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 98661fa..6addb4d 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -252,12 +252,25 @@ typedef int		(*inet_getfrag_t) (const vo
 					   char *,
 					   unsigned int, unsigned int);
 
-
-extern int		ipv6_addr_type(const struct in6_addr *addr);
+extern int __ipv6_addr_type(const struct in6_addr *addr);
+static inline int ipv6_addr_type(const struct in6_addr *addr)
+{
+	return __ipv6_addr_type(addr) & 0xffff;
+}
 
 static inline int ipv6_addr_scope(const struct in6_addr *addr)
 {
-	return ipv6_addr_type(addr) & IPV6_ADDR_SCOPE_MASK;
+	return __ipv6_addr_type(addr) & IPV6_ADDR_SCOPE_MASK;
+}
+
+static inline int __ipv6_addr_src_scope(int type)
+{
+	return (type == IPV6_ADDR_ANY ? __IPV6_ADDR_SCOPE_INVALID : (type >> 16));
+}
+
+static inline int ipv6_addr_src_scope(const struct in6_addr *addr)
+{
+	return __ipv6_addr_src_scope(__ipv6_addr_type(addr));
 }
 
 static inline int ipv6_addr_cmp(const struct in6_addr *a1, const struct in6_addr *a2)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 2c5f572..ff895da 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -35,6 +35,9 @@
  *	YOSHIFUJI Hideaki @USAGI	:	ARCnet support
  *	YOSHIFUJI Hideaki @USAGI	:	convert /proc/net/if_inet6 to
  *						seq_file.
+ *	YOSHIFUJI Hideaki @USAGI	:	improved source address
+ *						selection; consider scope,
+ *						status etc.
  */
 
 #include <linux/config.h>
@@ -193,46 +196,51 @@ const struct in6_addr in6addr_any = IN6A
 #endif
 const struct in6_addr in6addr_loopback = IN6ADDR_LOOPBACK_INIT;
 
-int ipv6_addr_type(const struct in6_addr *addr)
+#define IPV6_ADDR_SCOPE_TYPE(scope)	((scope) << 16)
+
+static inline unsigned ipv6_addr_scope2type(unsigned scope)
+{
+	switch(scope) {
+	case IPV6_ADDR_SCOPE_NODELOCAL:
+		return (IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_NODELOCAL) |
+			IPV6_ADDR_LOOPBACK);
+	case IPV6_ADDR_SCOPE_LINKLOCAL:
+		return (IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_LINKLOCAL) |
+			IPV6_ADDR_LINKLOCAL);
+	case IPV6_ADDR_SCOPE_SITELOCAL:
+		return (IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_SITELOCAL) |
+			IPV6_ADDR_SITELOCAL);
+	}
+	return IPV6_ADDR_SCOPE_TYPE(scope);
+}
+
+int __ipv6_addr_type(const struct in6_addr *addr)
 {
-	int type;
 	u32 st;
 
 	st = addr->s6_addr32[0];
 
-	if ((st & htonl(0xFF000000)) == htonl(0xFF000000)) {
-		type = IPV6_ADDR_MULTICAST;
-
-		switch((st & htonl(0x00FF0000))) {
-			case __constant_htonl(0x00010000):
-				type |= IPV6_ADDR_LOOPBACK;
-				break;
-
-			case __constant_htonl(0x00020000):
-				type |= IPV6_ADDR_LINKLOCAL;
-				break;
-
-			case __constant_htonl(0x00050000):
-				type |= IPV6_ADDR_SITELOCAL;
-				break;
-		};
-		return type;
-	}
-
-	type = IPV6_ADDR_UNICAST;
-
 	/* Consider all addresses with the first three bits different of
-	   000 and 111 as finished.
+	   000 and 111 as unicasts.
 	 */
 	if ((st & htonl(0xE0000000)) != htonl(0x00000000) &&
 	    (st & htonl(0xE0000000)) != htonl(0xE0000000))
-		return type;
-	
-	if ((st & htonl(0xFFC00000)) == htonl(0xFE800000))
-		return (IPV6_ADDR_LINKLOCAL | type);
+		return (IPV6_ADDR_UNICAST | 
+			IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_GLOBAL));
 
+	if ((st & htonl(0xFF000000)) == htonl(0xFF000000)) {
+		/* multicast */
+		/* addr-select 3.1 */
+		return (IPV6_ADDR_MULTICAST |
+			ipv6_addr_scope2type(IPV6_ADDR_MC_SCOPE(addr)));
+	}
+
+	if ((st & htonl(0xFFC00000)) == htonl(0xFE800000))
+		return (IPV6_ADDR_LINKLOCAL | IPV6_ADDR_UNICAST | 
+			IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_LINKLOCAL));		/* addr-select 3.1 */
 	if ((st & htonl(0xFFC00000)) == htonl(0xFEC00000))
-		return (IPV6_ADDR_SITELOCAL | type);
+		return (IPV6_ADDR_SITELOCAL | IPV6_ADDR_UNICAST |
+			IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_SITELOCAL));		/* addr-select 3.1 */
 
 	if ((addr->s6_addr32[0] | addr->s6_addr32[1]) == 0) {
 		if (addr->s6_addr32[2] == 0) {
@@ -240,24 +248,20 @@ int ipv6_addr_type(const struct in6_addr
 				return IPV6_ADDR_ANY;
 
 			if (addr->s6_addr32[3] == htonl(0x00000001))
-				return (IPV6_ADDR_LOOPBACK | type);
+				return (IPV6_ADDR_LOOPBACK | IPV6_ADDR_UNICAST |
+					IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_LINKLOCAL));	/* addr-select 3.4 */
 
-			return (IPV6_ADDR_COMPATv4 | type);
+			return (IPV6_ADDR_COMPATv4 | IPV6_ADDR_UNICAST |
+				IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_GLOBAL));	/* addr-select 3.3 */
 		}
 
 		if (addr->s6_addr32[2] == htonl(0x0000ffff))
-			return IPV6_ADDR_MAPPED;
+			return (IPV6_ADDR_MAPPED | 
+				IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_GLOBAL));	/* addr-select 3.3 */
 	}
 
-	st &= htonl(0xFF000000);
-	if (st == 0)
-		return IPV6_ADDR_RESERVED;
-	st &= htonl(0xFE000000);
-	if (st == htonl(0x02000000))
-		return IPV6_ADDR_RESERVED;	/* for NSAP */
-	if (st == htonl(0x04000000))
-		return IPV6_ADDR_RESERVED;	/* for IPX */
-	return type;
+	return (IPV6_ADDR_RESERVED | 
+		IPV6_ADDR_SCOPE_TYPE(IPV6_ADDR_SCOPE_GLOBAL));	/* addr-select 3.4 */
 }
 
 static void addrconf_del_timer(struct inet6_ifaddr *ifp)
diff --git a/net/ipv6/ipv6_syms.c b/net/ipv6/ipv6_syms.c
index 37a4a99..1648278 100644
--- a/net/ipv6/ipv6_syms.c
+++ b/net/ipv6/ipv6_syms.c
@@ -7,7 +7,7 @@
 #include <net/ip6_route.h>
 #include <net/xfrm.h>
 
-EXPORT_SYMBOL(ipv6_addr_type);
+EXPORT_SYMBOL(__ipv6_addr_type);
 EXPORT_SYMBOL(icmpv6_send);
 EXPORT_SYMBOL(icmpv6_statistics);
 EXPORT_SYMBOL(icmpv6_err_convert);
---
[IPV6]: RFC3484 compliant source address selection

Choose more appropriate source address; e.g.
 - outgoing interface
 - non-deprecated
 - scope
 - matching label

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index ff895da..a34d150 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -809,138 +809,274 @@ out:
 #endif
 
 /*
- *	Choose an appropriate source address
- *	should do:
- *	i)	get an address with an appropriate scope
- *	ii)	see if there is a specific route for the destination and use
- *		an address of the attached interface 
- *	iii)	don't use deprecated addresses
+ *	Choose an appropriate source address (RFC3484)
  */
-static int inline ipv6_saddr_pref(const struct inet6_ifaddr *ifp, u8 invpref)
+struct ipv6_saddr_score {
+	int		addr_type;
+	unsigned int	attrs;
+	int		matchlen;
+	unsigned int	scope;
+	unsigned int	rule;
+};
+
+#define IPV6_SADDR_SCORE_LOCAL		0x0001
+#define IPV6_SADDR_SCORE_PREFERRED	0x0004
+#define IPV6_SADDR_SCORE_HOA		0x0008
+#define IPV6_SADDR_SCORE_OIF		0x0010
+#define IPV6_SADDR_SCORE_LABEL		0x0020
+#define IPV6_SADDR_SCORE_PRIVACY	0x0040
+
+static int inline ipv6_saddr_preferred(int type)
 {
-	int pref;
-	pref = ifp->flags&IFA_F_DEPRECATED ? 0 : 2;
-#ifdef CONFIG_IPV6_PRIVACY
-	pref |= (ifp->flags^invpref)&IFA_F_TEMPORARY ? 0 : 1;
-#endif
-	return pref;
+	if (type & (IPV6_ADDR_MAPPED|IPV6_ADDR_COMPATv4|
+		    IPV6_ADDR_LOOPBACK|IPV6_ADDR_RESERVED))
+		return 1;
+	return 0;
 }
 
-#ifdef CONFIG_IPV6_PRIVACY
-#define IPV6_GET_SADDR_MAXSCORE(score)	((score) == 3)
-#else
-#define IPV6_GET_SADDR_MAXSCORE(score)	(score)
-#endif
+/* static matching label */
+static int inline ipv6_saddr_label(const struct in6_addr *addr, int type)
+{
+ /*
+  * 	prefix (longest match)	label
+  * 	-----------------------------
+  * 	::1/128			0
+  * 	::/0			1
+  * 	2002::/16		2
+  * 	::/96			3
+  * 	::ffff:0:0/96		4
+  */
+	if (type & IPV6_ADDR_LOOPBACK)
+		return 0;
+	else if (type & IPV6_ADDR_COMPATv4)
+		return 3;
+	else if (type & IPV6_ADDR_MAPPED)
+		return 4;
+	else if (addr->s6_addr16[0] == htons(0x2002))
+		return 2;
+	return 1;
+}
 
-int ipv6_dev_get_saddr(struct net_device *dev,
+int ipv6_dev_get_saddr(struct net_device *daddr_dev,
 		       struct in6_addr *daddr, struct in6_addr *saddr)
 {
-	struct inet6_ifaddr *ifp = NULL;
-	struct inet6_ifaddr *match = NULL;
-	struct inet6_dev *idev;
-	int scope;
-	int err;
-	int hiscore = -1, score;
+	struct ipv6_saddr_score hiscore;
+	struct inet6_ifaddr *ifa_result = NULL;
+	int daddr_type = __ipv6_addr_type(daddr);
+	int daddr_scope = __ipv6_addr_src_scope(daddr_type);
+	u32 daddr_label = ipv6_saddr_label(daddr, daddr_type);
+	struct net_device *dev;
 
-	scope = ipv6_addr_scope(daddr);
+	memset(&hiscore, 0, sizeof(hiscore));
 
-	/*
-	 *	known dev
-	 *	search dev and walk through dev addresses
-	 */
+	read_lock(&dev_base_lock);
+	read_lock(&addrconf_lock);
 
-	if (dev) {
-		if (dev->flags & IFF_LOOPBACK)
-			scope = IFA_HOST;
+	for (dev = dev_base; dev; dev=dev->next) {
+		struct inet6_dev *idev;
+		struct inet6_ifaddr *ifa;
+
+		/* Rule 0: Candidate Source Address (section 4)
+		 *  - multicast and link-local destination address,
+		 *    the set of candidate source address MUST only
+		 *    include addresses assigned to interfaces
+		 *    belonging to the same link as the outgoing
+		 *    interface.
+		 * (- For site-local destination addresses, the
+		 *    set of candidate source addresses MUST only
+		 *    include addresses assigned to interfaces
+		 *    belonging to the same site as the outgoing
+		 *    interface.)
+		 */
+		if ((daddr_type & IPV6_ADDR_MULTICAST ||
+		     daddr_scope <= IPV6_ADDR_SCOPE_LINKLOCAL) &&
+		    daddr_dev && dev != daddr_dev)
+			continue;
 
-		read_lock(&addrconf_lock);
 		idev = __in6_dev_get(dev);
-		if (idev) {
-			read_lock_bh(&idev->lock);
-			for (ifp=idev->addr_list; ifp; ifp=ifp->if_next) {
-				if (ifp->scope == scope) {
-					if (ifp->flags&IFA_F_TENTATIVE)
-						continue;
-#ifdef CONFIG_IPV6_PRIVACY
-					score = ipv6_saddr_pref(ifp, idev->cnf.use_tempaddr > 1 ? IFA_F_TEMPORARY : 0);
-#else
-					score = ipv6_saddr_pref(ifp, 0);
-#endif
-					if (score <= hiscore)
-						continue;
+		if (!idev)
+			continue;
 
-					if (match)
-						in6_ifa_put(match);
-					match = ifp;
-					hiscore = score;
-					in6_ifa_hold(ifp);
+		read_lock_bh(&idev->lock);
+		for (ifa = idev->addr_list; ifa; ifa = ifa->if_next) {
+			struct ipv6_saddr_score score;
 
-					if (IPV6_GET_SADDR_MAXSCORE(score)) {
-						read_unlock_bh(&idev->lock);
-						read_unlock(&addrconf_lock);
-						goto out;
-					}
+			score.addr_type = __ipv6_addr_type(&ifa->addr);
+
+			/* Rule 0: Candidate Source Address (section 4)
+			 *  - In any case, anycast addresses, multicast
+			 *    addresses, and the unspecified address MUST
+			 *    NOT be included in a candidate set.
+			 */
+			if (unlikely(score.addr_type == IPV6_ADDR_ANY ||
+				     score.addr_type & IPV6_ADDR_MULTICAST)) {
+				LIMIT_NETDEBUG(KERN_DEBUG
+					       "ADDRCONF: unspecified / multicast address"
+					       "assigned as unicast address on %s",
+					       dev->name);
+				continue;
+			}
+
+			score.attrs = 0;
+			score.matchlen = 0;
+			score.scope = 0;
+			score.rule = 0;
+
+			if (ifa_result == NULL) {
+				/* record it if the first available entry */
+				goto record_it;
+			}
+
+			/* Rule 1: Prefer same address */
+			if (hiscore.rule < 1) {
+				if (ipv6_addr_equal(&ifa_result->addr, daddr))
+					hiscore.attrs |= IPV6_SADDR_SCORE_LOCAL;
+				hiscore.rule++;
+			}
+			if (ipv6_addr_equal(&ifa->addr, daddr)) {
+				score.attrs |= IPV6_SADDR_SCORE_LOCAL;
+				if (!(hiscore.attrs & IPV6_SADDR_SCORE_LOCAL)) {
+					score.rule = 1;
+					goto record_it;
 				}
+			} else {
+				if (hiscore.attrs & IPV6_SADDR_SCORE_LOCAL)
+					continue;
 			}
-			read_unlock_bh(&idev->lock);
-		}
-		read_unlock(&addrconf_lock);
-	}
 
-	if (scope == IFA_LINK)
-		goto out;
+			/* Rule 2: Prefer appropriate scope */
+			if (hiscore.rule < 2) {
+				hiscore.scope = __ipv6_addr_src_scope(hiscore.addr_type);
+				hiscore.rule++;
+			}
+			score.scope = __ipv6_addr_src_scope(score.addr_type);
+			if (hiscore.scope < score.scope) {
+				if (hiscore.scope < daddr_scope) {
+					score.rule = 2;
+					goto record_it;
+				} else
+					continue;
+			} else if (score.scope < hiscore.scope) {
+				if (score.scope < daddr_scope)
+					continue;
+				else {
+					score.rule = 2;
+					goto record_it;
+				}
+			}
 
-	/*
-	 *	dev == NULL or search failed for specified dev
-	 */
+			/* Rule 3: Avoid deprecated address */
+			if (hiscore.rule < 3) {
+				if (ipv6_saddr_preferred(hiscore.addr_type) ||
+				    !(ifa_result->flags & IFA_F_DEPRECATED))
+					hiscore.attrs |= IPV6_SADDR_SCORE_PREFERRED;
+				hiscore.rule++;
+			}
+			if (ipv6_saddr_preferred(score.addr_type) ||
+			    !(ifa->flags & IFA_F_DEPRECATED)) {
+				score.attrs |= IPV6_SADDR_SCORE_PREFERRED;
+				if (!(hiscore.attrs & IPV6_SADDR_SCORE_PREFERRED)) {
+					score.rule = 3;
+					goto record_it;
+				}
+			} else {
+				if (hiscore.attrs & IPV6_SADDR_SCORE_PREFERRED)
+					continue;
+			}
 
-	read_lock(&dev_base_lock);
-	read_lock(&addrconf_lock);
-	for (dev = dev_base; dev; dev=dev->next) {
-		idev = __in6_dev_get(dev);
-		if (idev) {
-			read_lock_bh(&idev->lock);
-			for (ifp=idev->addr_list; ifp; ifp=ifp->if_next) {
-				if (ifp->scope == scope) {
-					if (ifp->flags&IFA_F_TENTATIVE)
-						continue;
-#ifdef CONFIG_IPV6_PRIVACY
-					score = ipv6_saddr_pref(ifp, idev->cnf.use_tempaddr > 1 ? IFA_F_TEMPORARY : 0);
-#else
-					score = ipv6_saddr_pref(ifp, 0);
-#endif
-					if (score <= hiscore)
-						continue;
+			/* Rule 4: Prefer home address -- not implemented yet */
 
-					if (match)
-						in6_ifa_put(match);
-					match = ifp;
-					hiscore = score;
-					in6_ifa_hold(ifp);
+			/* Rule 5: Prefer outgoing interface */
+			if (hiscore.rule < 5) {
+				if (daddr_dev == NULL ||
+				    daddr_dev == ifa_result->idev->dev)
+					hiscore.attrs |= IPV6_SADDR_SCORE_OIF;
+				hiscore.rule++;
+			}
+			if (daddr_dev == NULL ||
+			    daddr_dev == ifa->idev->dev) {
+				score.attrs |= IPV6_SADDR_SCORE_OIF;
+				if (!(hiscore.attrs & IPV6_SADDR_SCORE_OIF)) {
+					score.rule = 5;
+					goto record_it;
+				}
+			} else {
+				if (hiscore.attrs & IPV6_SADDR_SCORE_OIF)
+					continue;
+			}
 
-					if (IPV6_GET_SADDR_MAXSCORE(score)) {
-						read_unlock_bh(&idev->lock);
-						goto out_unlock_base;
-					}
+			/* Rule 6: Prefer matching label */
+			if (hiscore.rule < 6) {
+				if (ipv6_saddr_label(&ifa_result->addr, hiscore.addr_type) == daddr_label)
+					hiscore.attrs |= IPV6_SADDR_SCORE_LABEL;
+				hiscore.rule++;
+			}
+			if (ipv6_saddr_label(&ifa->addr, score.addr_type) == daddr_label) {
+				score.attrs |= IPV6_SADDR_SCORE_LABEL;
+				if (!(hiscore.attrs & IPV6_SADDR_SCORE_LABEL)) {
+					score.rule = 6;
+					goto record_it;
 				}
+			} else {
+				if (hiscore.attrs & IPV6_SADDR_SCORE_LABEL)
+					continue;
 			}
-			read_unlock_bh(&idev->lock);
+
+			/* Rule 7: Prefer public address
+			 * Note: prefer temprary address if use_tempaddr >= 2
+			 */
+			if (hiscore.rule < 7) {
+				if ((!(ifa_result->flags & IFA_F_TEMPORARY)) ^
+				    (ifa_result->idev->cnf.use_tempaddr >= 2))
+					hiscore.attrs |= IPV6_SADDR_SCORE_PRIVACY;
+				hiscore.rule++;
+			}
+			if ((!(ifa->flags & IFA_F_TEMPORARY)) ^
+			    (ifa->idev->cnf.use_tempaddr >= 2)) {
+				score.attrs |= IPV6_SADDR_SCORE_PRIVACY;
+				if (!(hiscore.attrs & IPV6_SADDR_SCORE_PRIVACY)) {
+					score.rule = 7;
+					goto record_it;
+				}
+			} else {
+				if (hiscore.attrs & IPV6_SADDR_SCORE_PRIVACY)
+					continue;
+			}
+
+			/* Rule 8: Use longest matching prefix */
+			if (hiscore.rule < 8)
+				hiscore.matchlen = ipv6_addr_diff(&ifa_result->addr, daddr);
+			score.rule++;
+			score.matchlen = ipv6_addr_diff(&ifa->addr, daddr);
+			if (score.matchlen > hiscore.matchlen) {
+				score.rule = 8;
+				goto record_it;
+			}
+#if 0
+			else if (score.matchlen < hiscore.matchlen)
+				continue;
+#endif
+
+			/* Final Rule: choose first available one */
+			continue;
+record_it:
+			if (ifa_result)
+				in6_ifa_put(ifa_result);
+			in6_ifa_hold(ifa);
+			ifa_result = ifa;
+			hiscore = score;
 		}
+		read_unlock_bh(&idev->lock);
 	}
-
-out_unlock_base:
 	read_unlock(&addrconf_lock);
 	read_unlock(&dev_base_lock);
 
-out:
-	err = -EADDRNOTAVAIL;
-	if (match) {
-		ipv6_addr_copy(saddr, &match->addr);
-		err = 0;
-		in6_ifa_put(match);
-	}
-
-	return err;
+	if (!ifa_result)
+		return -EADDRNOTAVAIL;
+	
+	ipv6_addr_copy(saddr, &ifa_result->addr);
+	in6_ifa_put(ifa_result);
+	return 0;
 }
 
 
---
-
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