net: ipv6: mcast: minor: use defines for rfc3810/8.1 lengths

Instead of hard-coding length values, use a define to make it clear
where those lengths come from.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 6 insertions, 3 deletions

diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c
index 33f98d9ac376..98ead2b1a669 100644
--- a/net/ipv6/mcast.c
+++ b/net/ipv6/mcast.c
@@ -107,9 +107,12 @@ static int ip6_mc_add_src(struct inet6_dev *idev, const struct in6_addr *pmca,
 static int ip6_mc_leave_src(struct sock *sk, struct ipv6_mc_socklist *iml,
                             struct inet6_dev *idev);
 
-
 #define MLD_QRV_DEFAULT         2
 
+/* RFC3810, 8.1 Query Version Distinctions */
+#define MLD_V1_QUERY_LEN        24
+#define MLD_V2_QUERY_LEN_MIN    28
+
 #define MLD_V1_SEEN(idev) (dev_net((idev)->dev)->ipv6.devconf_all->force_mld_version == 1 || \
                 (idev)->cnf.force_mld_version == 1 || \
                 ((idev)->mc_v1_seen && \
@@ -1146,7 +1149,7 @@ int igmp6_event_query(struct sk_buff *skb)
             !(group_type&IPV6_ADDR_MULTICAST))
                 return -EINVAL;
 
-        if (len == 24) {
+        if (len == MLD_V1_QUERY_LEN) {
                 int switchback;
                 /* MLDv1 router present */
 
@@ -1160,7 +1163,7 @@ int igmp6_event_query(struct sk_buff *skb)
                         __in6_dev_put(idev);
                 /* clear deleted report items */
                 mld_clear_delrec(idev);
-        } else if (len >= 28) {
+        } else if (len >= MLD_V2_QUERY_LEN_MIN) {
                 int srcs_offset = sizeof(struct mld2_query) -
                                   sizeof(struct icmp6hdr);
                 if (!pskb_may_pull(skb, srcs_offset))