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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 15:20:36 -0700
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /net/ipv4/ip_forward.c
Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
Diffstat (limited to 'net/ipv4/ip_forward.c')
-rw-r--r--net/ipv4/ip_forward.c127
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;
+}

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