1 files changed, 127 insertions, 0 deletions
diff --git a/net/ipv4/ip_forward.c b/net/ipv4/ip_forward.c
new file mode 100644
index 000000000000..77094aac6c28
--- /dev/null
+++ b/net/ipv4/ip_forward.c
@@ -0,0 +1,127 @@
+/*
+ * INET		An implementation of the TCP/IP protocol suite for the LINUX
+ *		operating system.  INET is implemented using the  BSD Socket
+ *		interface as the means of communication with the user level.
+ *
+ *		The IP forwarding functionality.
+ *		
+ * Version:	$Id: ip_forward.c,v 1.48 2000/12/13 18:31:48 davem Exp $
+ *
+ * Authors:	see ip.c
+ *
+ * Fixes:
+ *		Many		:	Split from ip.c , see ip_input.c for 
+ *					history.
+ *		Dave Gregorich	:	NULL ip_rt_put fix for multicast 
+ *					routing.
+ *		Jos Vos		:	Add call_out_firewall before sending,
+ *					use output device for accounting.
+ *		Jos Vos		:	Call forward firewall after routing
+ *					(always use output device).
+ *		Mike McLagan	:	Routing by source
+ */
+
+#include <linux/config.h>
+#include <linux/types.h>
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/skbuff.h>
+#include <linux/ip.h>
+#include <linux/icmp.h>
+#include <linux/netdevice.h>
+#include <net/sock.h>
+#include <net/ip.h>
+#include <net/tcp.h>
+#include <net/udp.h>
+#include <net/icmp.h>
+#include <linux/tcp.h>
+#include <linux/udp.h>
+#include <linux/netfilter_ipv4.h>
+#include <net/checksum.h>
+#include <linux/route.h>
+#include <net/route.h>
+#include <net/xfrm.h>
+
+static inline int ip_forward_finish(struct sk_buff *skb)
+{
+	struct ip_options * opt	= &(IPCB(skb)->opt);
+
+	IP_INC_STATS_BH(IPSTATS_MIB_OUTFORWDATAGRAMS);
+
+	if (unlikely(opt->optlen))
+		ip_forward_options(skb);
+
+	return dst_output(skb);
+}
+
+int ip_forward(struct sk_buff *skb)
+{
+	struct iphdr *iph;	/* Our header */
+	struct rtable *rt;	/* Route we use */
+	struct ip_options * opt	= &(IPCB(skb)->opt);
+
+	if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
+		goto drop;
+
+	if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb))
+		return NET_RX_SUCCESS;
+
+	if (skb->pkt_type != PACKET_HOST)
+		goto drop;
+
+	skb->ip_summed = CHECKSUM_NONE;
+	
+	/*
+	 *	According to the RFC, we must first decrease the TTL field. If
+	 *	that reaches zero, we must reply an ICMP control message telling
+	 *	that the packet's lifetime expired.
+	 */
+
+	iph = skb->nh.iph;
+
+	if (iph->ttl <= 1)
+                goto too_many_hops;
+
+	if (!xfrm4_route_forward(skb))
+		goto drop;
+
+	iph = skb->nh.iph;
+	rt = (struct rtable*)skb->dst;
+
+	if (opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
+		goto sr_failed;
+
+	/* We are about to mangle packet. Copy it! */
+	if (skb_cow(skb, LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len))
+		goto drop;
+	iph = skb->nh.iph;
+
+	/* Decrease ttl after skb cow done */
+	ip_decrease_ttl(iph);
+
+	/*
+	 *	We now generate an ICMP HOST REDIRECT giving the route
+	 *	we calculated.
+	 */
+	if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr)
+		ip_rt_send_redirect(skb);
+
+	skb->priority = rt_tos2priority(iph->tos);
+
+	return NF_HOOK(PF_INET, NF_IP_FORWARD, skb, skb->dev, rt->u.dst.dev,
+		       ip_forward_finish);
+
+sr_failed:
+        /*
+	 *	Strict routing permits no gatewaying
+	 */
+         icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0);
+         goto drop;
+
+too_many_hops:
+        /* Tell the sender its packet died... */
+        icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
+drop:
+	kfree_skb(skb);
+	return NET_RX_DROP;
+}