netfilter: nf_reject_ipv4: split nf_send_reset() in smaller functions

That can be reused by the reject bridge expression to build the reject
packet. The new functions are:

* nf_reject_ip_tcphdr_get(): to sanitize and to obtain the TCP header.
* nf_reject_iphdr_put(): to build the IPv4 header.
* nf_reject_ip_tcphdr_put(): to build the TCP header.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 10 insertions, 0 deletions

diff --git a/include/net/netfilter/ipv4/nf_reject.h b/include/net/netfilter/ipv4/nf_reject.h
index e8427193c777..03e928a55229 100644
--- a/include/net/netfilter/ipv4/nf_reject.h
+++ b/include/net/netfilter/ipv4/nf_reject.h
@@ -1,6 +1,8 @@
 #ifndef _IPV4_NF_REJECT_H
 #define _IPV4_NF_REJECT_H
 
+#include <linux/skbuff.h>
+#include <net/ip.h>
 #include <net/icmp.h>
 
 static inline void nf_send_unreach(struct sk_buff *skb_in, int code)
@@ -10,4 +12,12 @@ static inline void nf_send_unreach(struct sk_buff *skb_in, int code)
 
 void nf_send_reset(struct sk_buff *oldskb, int hook);
 
+const struct tcphdr *nf_reject_ip_tcphdr_get(struct sk_buff *oldskb,
+                                             struct tcphdr *_oth, int hook);
+struct iphdr *nf_reject_iphdr_put(struct sk_buff *nskb,
+                                  const struct sk_buff *oldskb,
+                                  __be16 protocol, int ttl);
+void nf_reject_ip_tcphdr_put(struct sk_buff *nskb, const struct sk_buff *oldskb,
+                             const struct tcphdr *oth);
+
 #endif /* _IPV4_NF_REJECT_H */