net: ipv6: Introduce ip6_sk_dst_hoplimit.

This replaces 6 identical code snippets with a call to a new
static inline function.

Signed-off-by: Lorenzo Colitti <lorenzo@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index d640925..5b40ad2 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -583,6 +583,11 @@
 	return (a->s6_addr32[0] & htonl(0xfffffff0)) == htonl(0x20010010);
 }
 
+static inline bool ipv6_addr_is_multicast(const struct in6_addr *addr)
+{
+	return (addr->s6_addr32[0] & htonl(0xFF000000)) == htonl(0xFF000000);
+}
+
 static inline void ipv6_addr_set_v4mapped(const __be32 addr,
 					  struct in6_addr *v4mapped)
 {
@@ -664,6 +669,20 @@
 
 int ip6_dst_hoplimit(struct dst_entry *dst);
 
+static inline int ip6_sk_dst_hoplimit(struct ipv6_pinfo *np, struct flowi6 *fl6,
+				      struct dst_entry *dst)
+{
+	int hlimit;
+
+	if (ipv6_addr_is_multicast(&fl6->daddr))
+		hlimit = np->mcast_hops;
+	else
+		hlimit = np->hop_limit;
+	if (hlimit < 0)
+		hlimit = ip6_dst_hoplimit(dst);
+	return hlimit;
+}
+
 /*
  *	Header manipulation
  */