[SLOF] [PATCH 2/6] net-snk: Fix the check for link-local addresses when receiving RAs

[Thomas Huth]

The code that checks whether the router advertisments contain only
a link-local address has a bug: It must check the full first 10 bits
of the address, not only the first 9 bits. Otherwise, site-local
addresses (which start with 0xFEC0...) are also recognized as
link-local, which is wrong, of course.
Fix it by also introducing a proper wrapper functions for link-local
addresses (which will be used in a later patch, too).

Signed-off-by: Thomas Huth <thuth at redhat.com>
---
 clients/net-snk/app/netlib/icmpv6.c | 4 ++--
 clients/net-snk/app/netlib/ipv6.h   | 7 +++++++
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/clients/net-snk/app/netlib/icmpv6.c b/clients/net-snk/app/netlib/icmpv6.c
index be6cc11..940b834 100644
--- a/clients/net-snk/app/netlib/icmpv6.c
+++ b/clients/net-snk/app/netlib/icmpv6.c
@@ -78,8 +78,8 @@ handle_prefixoption (uint8_t *option)
 	prefix_option = (struct option_prefix *) option;
 	memcpy( &(prefix.addr), &(prefix_option->prefix.addr), IPV6_ADDR_LENGTH);
 
-	/* Link-local adresses in RAs are nonsense                  */
-	if ( (IPV6_LL_PREFIX & (prefix_option->prefix.part.prefix)) == IPV6_LL_PREFIX )
+	/* Link-local adresses in RAs are nonsense */
+	if (ip6_is_linklocal(&prefix))
 		return;
 
 	if (prefix_option->preferred_lifetime > prefix_option->valid_lifetime)
diff --git a/clients/net-snk/app/netlib/ipv6.h b/clients/net-snk/app/netlib/ipv6.h
index b496364..963a1b0 100644
--- a/clients/net-snk/app/netlib/ipv6.h
+++ b/clients/net-snk/app/netlib/ipv6.h
@@ -26,6 +26,7 @@
 
 #define IPV6_ADDR_LENGTH	 16 /* Size of IPv6 adress in bytes */
 #define IPV6_LL_PREFIX		 0xFE80000000000000ULL
+#define IPV6_LL_PREFIX_MASK	 0xFFC0000000000000ULL
 #define IPV6_SOLIC_NODE_PREFIX   0xFF02000000000000ULL
 #define IPV6_SOLIC_NODE_IFACE_ID 0x00000001FF000000ULL
 
@@ -179,6 +180,12 @@ void * ip6_prefix2addr (ip6_addr_t prefix);
 /* Compare IPv6 adresses */
 int8_t ip6_cmp( ip6_addr_t *ip_1, ip6_addr_t *ip_2 );
 
+/* Check if it is a link-local address */
+static inline int ip6_is_linklocal(ip6_addr_t *ip)
+{
+	return (ip->part.prefix & IPV6_LL_PREFIX_MASK) == IPV6_LL_PREFIX;
+}
+
 /* Check if prefix is already in our list */
 int8_t unknown_prefix (ip6_addr_t *ip);
 
-- 
1.8.3.1