[NETFILTER] ip6tables: remove duplicate code

Some IPv6 matches have very similar loops to find IPv6 extension header
and we can unify them. This patch introduces ipv6_find_hdr() to do it.
I just checked that it can find the target headers in the packet which has
dst,hbh,rt,frag,ah,esp headers.

Signed-off-by: Yasuyuki Kozakai <yasuyuki.kozakai@toshiba.co.jp>
Signed-off-by: Harald Welte <laforge@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 76 deletions

diff --git a/net/ipv6/netfilter/ip6t_ah.c b/net/ipv6/netfilter/ip6t_ah.c
index d5b94f142bb..dde37793d20 100644
--- a/net/ipv6/netfilter/ip6t_ah.c
+++ b/net/ipv6/netfilter/ip6t_ah.c
@@ -48,92 +48,21 @@ match(const struct sk_buff *skb,
       unsigned int protoff,
       int *hotdrop)
 {
-	struct ip_auth_hdr *ah = NULL, _ah;
+	struct ip_auth_hdr *ah, _ah;
 	const struct ip6t_ah *ahinfo = matchinfo;
-	unsigned int temp;
-	int len;
-	u8 nexthdr;
 	unsigned int ptr;
 	unsigned int hdrlen = 0;
 
-	/*DEBUGP("IPv6 AH entered\n");*/
-	/* if (opt->auth == 0) return 0;
-	* It does not filled on output */
-
-	/* type of the 1st exthdr */
-	nexthdr = skb->nh.ipv6h->nexthdr;
-	/* pointer to the 1st exthdr */
-	ptr = sizeof(struct ipv6hdr);
-	/* available length */
-	len = skb->len - ptr;
-	temp = 0;
-
-	while (ip6t_ext_hdr(nexthdr)) {
-		struct ipv6_opt_hdr _hdr, *hp;
-
-		DEBUGP("ipv6_ah header iteration \n");
-
-		/* Is there enough space for the next ext header? */
-		if (len < sizeof(struct ipv6_opt_hdr))
-			return 0;
-		/* No more exthdr -> evaluate */
-		if (nexthdr == NEXTHDR_NONE)
-			break;
-		/* ESP -> evaluate */
-		if (nexthdr == NEXTHDR_ESP)
-			break;
-
-		hp = skb_header_pointer(skb, ptr, sizeof(_hdr), &_hdr);
-		BUG_ON(hp == NULL);
-
-		/* Calculate the header length */
-		if (nexthdr == NEXTHDR_FRAGMENT)
-			hdrlen = 8;
-		else if (nexthdr == NEXTHDR_AUTH)
-			hdrlen = (hp->hdrlen+2)<<2;
-		else
-			hdrlen = ipv6_optlen(hp);
-
-		/* AH -> evaluate */
-		if (nexthdr == NEXTHDR_AUTH) {
-			temp |= MASK_AH;
-			break;
-		}
-
-		
-		/* set the flag */
-		switch (nexthdr) {
-		case NEXTHDR_HOP:
-		case NEXTHDR_ROUTING:
-		case NEXTHDR_FRAGMENT:
-		case NEXTHDR_AUTH:
-		case NEXTHDR_DEST:
-			break;
-		default:
-			DEBUGP("ipv6_ah match: unknown nextheader %u\n",nexthdr);
-			return 0;
-		}
-
-		nexthdr = hp->nexthdr;
-		len -= hdrlen;
-		ptr += hdrlen;
-		if (ptr > skb->len) {
-			DEBUGP("ipv6_ah: new pointer too large! \n");
-			break;
-		}
-	}
-
-	/* AH header not found */
-	if (temp != MASK_AH)
+	if (ipv6_find_hdr(skb, &ptr, NEXTHDR_AUTH) < 0)
 		return 0;
 
-	if (len < sizeof(struct ip_auth_hdr)){
+	ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
+	if (ah == NULL) {
 		*hotdrop = 1;
 		return 0;
 	}
 
-	ah = skb_header_pointer(skb, ptr, sizeof(_ah), &_ah);
-	BUG_ON(ah == NULL);
+	hdrlen = (ah->hdrlen + 2) << 2;
 
 	DEBUGP("IPv6 AH LEN %u %u ", hdrlen, ah->hdrlen);
 	DEBUGP("RES %04X ", ah->reserved);