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[PATCH net-next 7/7] ipv6: Store Router Alert option in IP6CB directly.

From: YOSHIFUJI Hideaki <hidden>
Date: 2013-01-13 15:02:47
Subsystem: networking [general], networking [ipv4/ipv6], the rest · Maintainers: "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, David Ahern, Ido Schimmel, Linus Torvalds

Router Alert option is very small and we can store the value
itself in the skb.

Signed-off-by: YOSHIFUJI Hideaki <redacted>
---
 include/linux/ipv6.h      |    3 ++-
 include/uapi/linux/ipv6.h |    2 ++
 net/ipv6/exthdrs.c        |    3 ++-
 net/ipv6/ip6_input.c      |    5 ++---
 4 files changed, 8 insertions(+), 5 deletions(-)
diff --git a/include/linux/ipv6.h b/include/linux/ipv6.h
index 304a9f4..e971e37 100644
--- a/include/linux/ipv6.h
+++ b/include/linux/ipv6.h
@@ -84,7 +84,7 @@ static inline struct ipv6hdr *ipipv6_hdr(const struct sk_buff *skb)
 
 struct inet6_skb_parm {
 	int			iif;
-	__u16			ra;
+	__be16			ra;
 	__u16			hop;
 	__u16			dst0;
 	__u16			srcrt;
@@ -100,6 +100,7 @@ struct inet6_skb_parm {
 #define IP6SKB_XFRM_TRANSFORMED	1
 #define IP6SKB_FORWARDED	2
 #define IP6SKB_REROUTED		4
+#define IP6SKB_ROUTERALERT	8
 };
 
 #define IP6CB(skb)	((struct inet6_skb_parm*)((skb)->cb))
diff --git a/include/uapi/linux/ipv6.h b/include/uapi/linux/ipv6.h
index 5a2991c..4bda4cf 100644
--- a/include/uapi/linux/ipv6.h
+++ b/include/uapi/linux/ipv6.h
@@ -63,6 +63,8 @@ struct ipv6_opt_hdr {
 #define ipv6_destopt_hdr ipv6_opt_hdr
 #define ipv6_hopopt_hdr  ipv6_opt_hdr
 
+/* Router Alert option values (RFC2711) */
+#define IPV6_OPT_ROUTERALERT_MLD	0x0000	/* MLD(RFC2710) */
 
 /*
  *	routing header type 0 (used in cmsghdr struct)
diff --git a/net/ipv6/exthdrs.c b/net/ipv6/exthdrs.c
index 473f628..07a7d65 100644
--- a/net/ipv6/exthdrs.c
+++ b/net/ipv6/exthdrs.c
@@ -553,7 +553,8 @@ static bool ipv6_hop_ra(struct sk_buff *skb, int optoff)
 	const unsigned char *nh = skb_network_header(skb);
 
 	if (nh[optoff + 1] == 2) {
-		IP6CB(skb)->ra = optoff;
+		IP6CB(skb)->flags |= IP6SKB_ROUTERALERT;
+		memcpy(&IP6CB(skb)->ra, nh + optoff + 2, sizeof(IP6CB(skb)->ra));
 		return true;
 	}
 	LIMIT_NETDEBUG(KERN_DEBUG "ipv6_hop_ra: wrong RA length %d\n",
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index 2ccd35e..4ac5bf3 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -280,9 +280,8 @@ int ip6_mc_input(struct sk_buff *skb)
 		struct inet6_skb_parm *opt = IP6CB(skb);
 
 		/* Check for MLD */
-		if (unlikely(opt->ra)) {
+		if (unlikely(opt->flags & IP6SKB_ROUTERALERT)) {
 			/* Check if this is a mld message */
-			u8 *ptr = skb_network_header(skb) + opt->ra;
 			u8 nexthdr = hdr->nexthdr;
 			__be16 frag_off;
 			int offset;
@@ -290,7 +289,7 @@ int ip6_mc_input(struct sk_buff *skb)
 			/* Check if the value of Router Alert
 			 * is for MLD (0x0000).
 			 */
-			if ((ptr[2] | ptr[3]) == 0) {
+			if (opt->ra == htons(IPV6_OPT_ROUTERALERT_MLD)) {
 				deliver = false;
 
 				if (!ipv6_ext_hdr(nexthdr)) {
-- 
1.7.9.5
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