ipv6: Compare addresses only bits up to the prefix length (RFC6724).

Compare bits up to the source address's prefix length only to
allows DNS load balancing to continue to be used as a tie breaker.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 1237d5d037d82750b9aad892446f3f6be620abdf..5fd8ec895c8b71980c2a79cfc48cfc0d672907ac 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -1070,8 +1070,10 @@ static int ipv6_get_saddr_eval(struct net *net,
                break;
        case IPV6_SADDR_RULE_PREFIX:
                /* Rule 8: Use longest matching prefix */
-               score->matchlen = ret = ipv6_addr_diff(&score->ifa->addr,
-                                                      dst->addr);
+               ret = ipv6_addr_diff(&score->ifa->addr, dst->addr);
+               if (ret > score->ifa->prefix_len)
+                       ret = score->ifa->prefix_len;
+               score->matchlen = ret;
                break;
        default:
                ret = 0;