[IPV6]: Move nextheader offset to the IP6CB

Move nextheader offset to the IP6CB to make it possible to pass a
packet to ip6_input_finish multiple times and have it skip already
parsed headers. As a nice side effect this gets rid of the manual
hopopts skipping in ip6_input_finish.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ip6_input.c b/net/ipv6/ip6_input.c
index a6026d2..13d7241 100644
--- a/net/ipv6/ip6_input.c
+++ b/net/ipv6/ip6_input.c
@@ -97,6 +97,9 @@
 	if (hdr->version != 6)
 		goto err;
 
+	skb->h.raw = (u8 *)(hdr + 1);
+	IP6CB(skb)->nhoff = offsetof(struct ipv6hdr, nexthdr);
+
 	pkt_len = ntohs(hdr->payload_len);
 
 	/* pkt_len may be zero if Jumbo payload option is present */
@@ -111,8 +114,7 @@
 	}
 
 	if (hdr->nexthdr == NEXTHDR_HOP) {
-		skb->h.raw = (u8*)(hdr+1);
-		if (ipv6_parse_hopopts(skb, offsetof(struct ipv6hdr, nexthdr)) < 0) {
+		if (ipv6_parse_hopopts(skb, IP6CB(skb)->nhoff) < 0) {
 			IP6_INC_STATS_BH(IPSTATS_MIB_INHDRERRORS);
 			return 0;
 		}
@@ -143,26 +145,15 @@
 	int nexthdr;
 	u8 hash;
 
-	skb->h.raw = skb->nh.raw + sizeof(struct ipv6hdr);
-
 	/*
 	 *	Parse extension headers
 	 */
 
-	nexthdr = skb->nh.ipv6h->nexthdr;
-	nhoff = offsetof(struct ipv6hdr, nexthdr);
-
-	/* Skip hop-by-hop options, they are already parsed. */
-	if (nexthdr == NEXTHDR_HOP) {
-		nhoff = sizeof(struct ipv6hdr);
-		nexthdr = skb->h.raw[0];
-		skb->h.raw += (skb->h.raw[1]+1)<<3;
-	}
-
 	rcu_read_lock();
 resubmit:
 	if (!pskb_pull(skb, skb->h.raw - skb->data))
 		goto discard;
+	nhoff = IP6CB(skb)->nhoff;
 	nexthdr = skb->nh.raw[nhoff];
 
 	raw_sk = sk_head(&raw_v6_htable[nexthdr & (MAX_INET_PROTOS - 1)]);
@@ -194,7 +185,7 @@
 		    !xfrm6_policy_check(NULL, XFRM_POLICY_IN, skb)) 
 			goto discard;
 		
-		ret = ipprot->handler(&skb, &nhoff);
+		ret = ipprot->handler(&skb);
 		if (ret > 0)
 			goto resubmit;
 		else if (ret == 0)