[IPSEC]: Get rid of ipv6_{auth,esp,comp}_hdr

This patch removes the duplicate ipv6_{auth,esp,comp}_hdr structures since
they're identical to the IPv4 versions.  Duplicating them would only create
problems for ourselves later when we need to add things like extended
sequence numbers.

I've also added transport header type conversion headers for these types
which are now used by the transforms.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/ah.h

@@ -38,4 +38,11 @@ out:
 	return err;
 }
 
+struct ip_auth_hdr;
+
+static inline struct ip_auth_hdr *ip_auth_hdr(const struct sk_buff *skb)
+{
+	return (struct ip_auth_hdr *)skb_transport_header(skb);
+}
+
 #endif

include/net/esp.h

@@ -53,4 +53,11 @@ static inline int esp_mac_digest(struct esp_data *esp, struct sk_buff *skb,
 	return crypto_hash_final(&desc, esp->auth.work_icv);
 }
 
+struct ip_esp_hdr;
+
+static inline struct ip_esp_hdr *ip_esp_hdr(const struct sk_buff *skb)
+{
+	return (struct ip_esp_hdr *)skb_transport_header(skb);
+}
+
 #endif

include/net/ipcomp.h

@@ -1,14 +1,23 @@
 #ifndef _NET_IPCOMP_H
 #define _NET_IPCOMP_H
 
-#include <linux/crypto.h>
 #include <linux/types.h>
 
 #define IPCOMP_SCRATCH_SIZE     65400
 
+struct crypto_comp;
+
 struct ipcomp_data {
 	u16 threshold;
 	struct crypto_comp **tfms;
 };
 
+struct ip_comp_hdr;
+struct sk_buff;
+
+static inline struct ip_comp_hdr *ip_comp_hdr(const struct sk_buff *skb)
+{
+	return (struct ip_comp_hdr *)skb_transport_header(skb);
+}
+
 #endif