[NET]: Move netfilter checksum helpers to net/core/utils.c

This allows to get rid of the CONFIG_NETFILTER dependency of NET_ACT_NAT.
This patch redefines the old names to keep the noise low, the next patch
converts all users.

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

1 files changed, 25 insertions, 0 deletions

diff --git a/include/net/checksum.h b/include/net/checksum.h
index 124246172a88..07602b7fa218 100644
--- a/include/net/checksum.h
+++ b/include/net/checksum.h
@@ -93,4 +93,29 @@ static inline __wsum csum_unfold(__sum16 n)
 }
 
 #define CSUM_MANGLED_0 ((__force __sum16)0xffff)
+
+static inline void csum_replace4(__sum16 *sum, __be32 from, __be32 to)
+{
+        __be32 diff[] = { ~from, to };
+
+        *sum = csum_fold(csum_partial((char *)diff, sizeof(diff), ~csum_unfold(*sum)));
+}
+
+static inline void csum_replace2(__sum16 *sum, __be16 from, __be16 to)
+{
+        csum_replace4(sum, (__force __be32)from, (__force __be32)to);
+}
+
+struct sk_buff;
+extern void inet_proto_csum_replace4(__sum16 *sum, struct sk_buff *skb,
+                                     __be32 from, __be32 to, int pseudohdr);
+
+static inline void inet_proto_csum_replace2(__sum16 *sum, struct sk_buff *skb,
+                                            __be16 from, __be16 to,
+                                            int pseudohdr)
+{
+        inet_proto_csum_replace4(sum, skb, (__force __be32)from,
+                                 (__force __be32)to, pseudohdr);
+}
+
 #endif