[PATCH] netfilter: remove duplicate code

nf_nat_ipv4_fn() and nf_nat_ipv6_fn() call nf_nat_inet_fn().
Those two functions are already contains routine that gets nf_conn
object and checks the untrackable situation.
So, the following code is duplicated.

ct = nf_ct_get(skb, &ctinfo);
if (!ct)
        return NF_ACCEPT;

Therefore, define a function __nf_nat_inet_fn() that has the same
contents as the nf_nat_inet_fn() except for routine gets and checks
the nf_conn object.
Then, separate the nf_nat_inet_fn() into a routine that gets a
nf_conn object and a routine that calls the __nf_nat_inet_fn().

Signed-off-by: Kangmin Park <redacted>
---
 include/net/netfilter/nf_nat.h |  5 +++++
 net/netfilter/nf_nat_core.c    | 37 ++++++++++++++++++++++------------
 net/netfilter/nf_nat_proto.c   |  4 ++--
 3 files changed, 31 insertions(+), 15 deletions(-)

diff --git a/include/net/netfilter/nf_nat.h b/include/net/netfilter/nf_nat.h
index 987111ae5240..a66f617c5054 100644
--- a/include/net/netfilter/nf_nat.h
+++ b/include/net/netfilter/nf_nat.h

@@ -100,6 +100,11 @@ void nf_nat_ipv6_unregister_fn(struct net *net, const struct nf_hook_ops *ops);
 int nf_nat_inet_register_fn(struct net *net, const struct nf_hook_ops *ops);
 void nf_nat_inet_unregister_fn(struct net *net, const struct nf_hook_ops *ops);

+unsigned int
+__nf_nat_inet_fn(void *priv, struct sk_buff *skb,
+                const struct nf_hook_state *state, struct nf_conn *ct,
+                enum ip_conntrack_info ctinfo);
+
 unsigned int
 nf_nat_inet_fn(void *priv, struct sk_buff *skb,
               const struct nf_hook_state *state);

diff --git a/net/netfilter/nf_nat_core.c b/net/netfilter/nf_nat_core.c
index 7de595ead06a..98ebba2c0f6d 100644
--- a/net/netfilter/nf_nat_core.c
+++ b/net/netfilter/nf_nat_core.c

@@ -682,25 +682,15 @@ unsigned int nf_nat_packet(struct nf_conn *ct,
 }
 EXPORT_SYMBOL_GPL(nf_nat_packet);

 unsigned int
-nf_nat_inet_fn(void *priv, struct sk_buff *skb,
-              const struct nf_hook_state *state)
+__nf_nat_inet_fn(void *priv, struct sk_buff *skb,
+                const struct nf_hook_state *state, struct nf_conn *ct,
+                enum ip_conntrack_info ctinfo)
 {
-       struct nf_conn *ct;
-       enum ip_conntrack_info ctinfo;
        struct nf_conn_nat *nat;
        /* maniptype == SRC for postrouting. */
        enum nf_nat_manip_type maniptype = HOOK2MANIP(state->hook);

-       ct = nf_ct_get(skb, &ctinfo);
-       /* Can't track?  It's not due to stress, or conntrack would
-        * have dropped it.  Hence it's the user's responsibilty to
-        * packet filter it out, or implement conntrack/NAT for that
-        * protocol. 8) --RR
-        */
-       if (!ct)
-               return NF_ACCEPT;
-
        nat = nfct_nat(ct);

        switch (ctinfo) {

@@ -755,6 +745,26 @@ nf_nat_inet_fn(void *priv, struct sk_buff *skb,
        nf_ct_kill_acct(ct, ctinfo, skb);
        return NF_DROP;
 }
+EXPORT_SYMBOL_GPL(__nf_nat_inet_fn);
+
+unsigned int
+nf_nat_inet_fn(void *priv, struct sk_buff *skb,
+              const struct nf_hook_state *state)
+{
+       struct nf_conn *ct;
+       enum ip_conntrack_info ctinfo;
+
+       ct = nf_ct_get(skb, &ctinfo);
+       /* Can't track?  It's not due to stress, or conntrack would
+        * have dropped it.  Hence it's the user's responsibilty to
+        * packet filter it out, or implement conntrack/NAT for that
+        * protocol. 8) --RR
+        */
+       if (!ct)
+               return NF_ACCEPT;
+
+       return __nf_nat_inet_fn(priv, skb, state, ct, ctinfo);
+}
 EXPORT_SYMBOL_GPL(nf_nat_inet_fn);

 struct nf_nat_proto_clean {

diff --git a/net/netfilter/nf_nat_proto.c b/net/netfilter/nf_nat_proto.c
index 48cc60084d28..897859730078 100644
--- a/net/netfilter/nf_nat_proto.c
+++ b/net/netfilter/nf_nat_proto.c

@@ -642,7 +642,7 @@ nf_nat_ipv4_fn(void *priv, struct sk_buff *skb,
                }
        }

-       return nf_nat_inet_fn(priv, skb, state);
+       return __nf_nat_inet_fn(priv, skb, state, ct, ctinfo);
 }

 static unsigned int

@@ -934,7 +934,7 @@ nf_nat_ipv6_fn(void *priv, struct sk_buff *skb,
                }
        }

-       return nf_nat_inet_fn(priv, skb, state);
+       return __nf_nat_inet_fn(priv, skb, state, ct, ctinfo);
 }

 static unsigned int
--

2.26.2