[IPV4]: Add ip_local_out

Most callers of the LOCAL_OUT chain will set the IP packet length and
header checksum before doing so.  They also share the same output
function dst_output.

This patch creates a new function called ip_local_out which does all
of that and converts the appropriate users over to it.

Apart from removing duplicate code, it will also help in merging the
IPsec output path once the same thing is done for IPv6.

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

1 files changed, 25 insertions, 14 deletions

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index bc9e57550e8..03b9b060027 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -91,6 +91,28 @@ __inline__ void ip_send_check(struct iphdr *iph)
 	iph->check = ip_fast_csum((unsigned char *)iph, iph->ihl);
 }
 
+int __ip_local_out(struct sk_buff *skb)
+{
+	struct iphdr *iph = ip_hdr(skb);
+
+	iph->tot_len = htons(skb->len);
+	ip_send_check(iph);
+	return nf_hook(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, skb->dst->dev,
+		       dst_output);
+}
+
+int ip_local_out(struct sk_buff *skb)
+{
+	int err;
+
+	err = __ip_local_out(skb);
+	if (likely(err == 1))
+		err = dst_output(skb);
+
+	return err;
+}
+EXPORT_SYMBOL_GPL(ip_local_out);
+
 /* dev_loopback_xmit for use with netfilter. */
 static int ip_dev_loopback_xmit(struct sk_buff *newskb)
 {
@@ -138,20 +160,17 @@ int ip_build_and_send_pkt(struct sk_buff *skb, struct sock *sk,
 	iph->daddr    = rt->rt_dst;
 	iph->saddr    = rt->rt_src;
 	iph->protocol = sk->sk_protocol;
-	iph->tot_len  = htons(skb->len);
 	ip_select_ident(iph, &rt->u.dst, sk);
 
 	if (opt && opt->optlen) {
 		iph->ihl += opt->optlen>>2;
 		ip_options_build(skb, opt, daddr, rt, 0);
 	}
-	ip_send_check(iph);
 
 	skb->priority = sk->sk_priority;
 
 	/* Send it out. */
-	return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
-		       dst_output);
+	return ip_local_out(skb);
 }
 
 EXPORT_SYMBOL_GPL(ip_build_and_send_pkt);
@@ -347,7 +366,6 @@ packet_routed:
 	skb_reset_network_header(skb);
 	iph = ip_hdr(skb);
 	*((__be16 *)iph) = htons((4 << 12) | (5 << 8) | (inet->tos & 0xff));
-	iph->tot_len = htons(skb->len);
 	if (ip_dont_fragment(sk, &rt->u.dst) && !ipfragok)
 		iph->frag_off = htons(IP_DF);
 	else
@@ -366,13 +384,9 @@ packet_routed:
 	ip_select_ident_more(iph, &rt->u.dst, sk,
 			     (skb_shinfo(skb)->gso_segs ?: 1) - 1);
 
-	/* Add an IP checksum. */
-	ip_send_check(iph);
-
 	skb->priority = sk->sk_priority;
 
-	return NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL, rt->u.dst.dev,
-		       dst_output);
+	return ip_local_out(skb);
 
 no_route:
 	IP_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
@@ -1262,14 +1276,12 @@ int ip_push_pending_frames(struct sock *sk)
 		ip_options_build(skb, opt, inet->cork.addr, rt, 0);
 	}
 	iph->tos = inet->tos;
-	iph->tot_len = htons(skb->len);
 	iph->frag_off = df;
 	ip_select_ident(iph, &rt->u.dst, sk);
 	iph->ttl = ttl;
 	iph->protocol = sk->sk_protocol;
 	iph->saddr = rt->rt_src;
 	iph->daddr = rt->rt_dst;
-	ip_send_check(iph);
 
 	skb->priority = sk->sk_priority;
 	skb->dst = dst_clone(&rt->u.dst);
@@ -1279,8 +1291,7 @@ int ip_push_pending_frames(struct sock *sk)
 			skb_transport_header(skb))->type);
 
 	/* Netfilter gets whole the not fragmented skb. */
-	err = NF_HOOK(PF_INET, NF_IP_LOCAL_OUT, skb, NULL,
-		      skb->dst->dev, dst_output);
+	err = ip_local_out(skb);
 	if (err) {
 		if (err > 0)
 			err = inet->recverr ? net_xmit_errno(err) : 0;