+/* Multipath route selection:
+ * Hash based function using packet header and flowlabel.
+ * Adapted from fib_info_hashfn()
+ */
+static int rt6_info_hash_nhsfn(unsigned int candidate_count,
+ const struct flowi6 *fl6)
+{
+ unsigned int val = fl6->flowi6_proto;
+
+ val ^= (__force u32)fl6->daddr.s6_addr32[0];
+ val ^= (__force u32)fl6->daddr.s6_addr32[1];
+ val ^= (__force u32)fl6->daddr.s6_addr32[2];
+ val ^= (__force u32)fl6->daddr.s6_addr32[3];
+
+ val ^= (__force u32)fl6->saddr.s6_addr32[0];
+ val ^= (__force u32)fl6->saddr.s6_addr32[1];
+ val ^= (__force u32)fl6->saddr.s6_addr32[2];
+ val ^= (__force u32)fl6->saddr.s6_addr32[3];
+
+ /* Work only if this not encapsulated */
+ switch (fl6->flowi6_proto) {
+ case IPPROTO_UDP:
+ case IPPROTO_TCP:
+ case IPPROTO_SCTP:
+ val ^= (__force u16)fl6->fl6_sport;
+ val ^= (__force u16)fl6->fl6_dport;
+ break;
+
+ case IPPROTO_ICMPV6:
+ val ^= (__force u16)fl6->fl6_icmp_type;
+ val ^= (__force u16)fl6->fl6_icmp_code;
+ break;
+ }
+ /* RFC6438 recommands to use flowlabel */
+ val ^= (__force u32)fl6->flowlabel;
+
+ /* Perhaps, we need to tune, this function? */
+ val = val ^ (val >> 7) ^ (val >> 12);
+ return val % candidate_count;
+}
+
+static struct rt6_info *rt6_multipath_select(struct rt6_info *match,
+ struct flowi6 *fl6)
+{
+ struct rt6_info *sibling, *next_sibling;
+ int route_choosen;
+
+ route_choosen = rt6_info_hash_nhsfn(match->rt6i_nsiblings + 1, fl6);
+ /* Don't change the route, if route_choosen == 0
+ * (siblings does not include ourself)
+ */
+ if (route_choosen)
+ list_for_each_entry_safe(sibling, next_sibling,
+ &match->rt6i_siblings, rt6i_siblings) {
+ route_choosen--;
+ if (route_choosen == 0) {
+ match = sibling;
+ break;
+ }
+ }
+ return match;
+}
+