[NETFILTER]: Use in-kernel IPSEC structures in iptables ah (by Patrick McHardy).

net/ipv4/netfilter/ipt_ah.c

 /* Kernel module to match AH parameters. */
 #include <linux/module.h>
 #include <linux/skbuff.h>
+#include <linux/ip.h>
 
 #include <linux/netfilter_ipv4/ipt_ah.h>
 #include <linux/netfilter_ipv4/ip_tables.h>
@@ -13,10 +14,6 @@ MODULE_LICENSE("GPL");
 #define duprintf(format, args...)
 #endif
 
-struct ahhdr {
-	__u32   spi;
-};
-
 /* Returns 1 if the spi is matched by the range, 0 otherwise */
 static inline int
 spi_match(u_int32_t min, u_int32_t max, u_int32_t spi, int invert)
@@ -37,7 +34,7 @@ match(const struct sk_buff *skb,
       int offset,
       int *hotdrop)
 {
-	struct ahhdr ah;
+	struct ip_auth_hdr ah;
 	const struct ipt_ah *ahinfo = matchinfo;
 
 	/* Must not be a fragment. */