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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-16 18:20:36 -0400
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /net/ipv4/ip_forward.c
Linux-2.6.12-rc2v2.6.12-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 @@
1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * The IP forwarding functionality.
7 *
8 * Version: $Id: ip_forward.c,v 1.48 2000/12/13 18:31:48 davem Exp $
9 *
10 * Authors: see ip.c
11 *
12 * Fixes:
13 * Many : Split from ip.c , see ip_input.c for
14 * history.
15 * Dave Gregorich : NULL ip_rt_put fix for multicast
16 * routing.
17 * Jos Vos : Add call_out_firewall before sending,
18 * use output device for accounting.
19 * Jos Vos : Call forward firewall after routing
20 * (always use output device).
21 * Mike McLagan : Routing by source
22 */
23
24#include <linux/config.h>
25#include <linux/types.h>
26#include <linux/mm.h>
27#include <linux/sched.h>
28#include <linux/skbuff.h>
29#include <linux/ip.h>
30#include <linux/icmp.h>
31#include <linux/netdevice.h>
32#include <net/sock.h>
33#include <net/ip.h>
34#include <net/tcp.h>
35#include <net/udp.h>
36#include <net/icmp.h>
37#include <linux/tcp.h>
38#include <linux/udp.h>
39#include <linux/netfilter_ipv4.h>
40#include <net/checksum.h>
41#include <linux/route.h>
42#include <net/route.h>
43#include <net/xfrm.h>
44
45static inline int ip_forward_finish(struct sk_buff *skb)
46{
47 struct ip_options * opt = &(IPCB(skb)->opt);
48
49 IP_INC_STATS_BH(IPSTATS_MIB_OUTFORWDATAGRAMS);
50
51 if (unlikely(opt->optlen))
52 ip_forward_options(skb);
53
54 return dst_output(skb);
55}
56
57int ip_forward(struct sk_buff *skb)
58{
59 struct iphdr *iph; /* Our header */
60 struct rtable *rt; /* Route we use */
61 struct ip_options * opt = &(IPCB(skb)->opt);
62
63 if (!xfrm4_policy_check(NULL, XFRM_POLICY_FWD, skb))
64 goto drop;
65
66 if (IPCB(skb)->opt.router_alert && ip_call_ra_chain(skb))
67 return NET_RX_SUCCESS;
68
69 if (skb->pkt_type != PACKET_HOST)
70 goto drop;
71
72 skb->ip_summed = CHECKSUM_NONE;
73
74 /*
75 * According to the RFC, we must first decrease the TTL field. If
76 * that reaches zero, we must reply an ICMP control message telling
77 * that the packet's lifetime expired.
78 */
79
80 iph = skb->nh.iph;
81
82 if (iph->ttl <= 1)
83 goto too_many_hops;
84
85 if (!xfrm4_route_forward(skb))
86 goto drop;
87
88 iph = skb->nh.iph;
89 rt = (struct rtable*)skb->dst;
90
91 if (opt->is_strictroute && rt->rt_dst != rt->rt_gateway)
92 goto sr_failed;
93
94 /* We are about to mangle packet. Copy it! */
95 if (skb_cow(skb, LL_RESERVED_SPACE(rt->u.dst.dev)+rt->u.dst.header_len))
96 goto drop;
97 iph = skb->nh.iph;
98
99 /* Decrease ttl after skb cow done */
100 ip_decrease_ttl(iph);
101
102 /*
103 * We now generate an ICMP HOST REDIRECT giving the route
104 * we calculated.
105 */
106 if (rt->rt_flags&RTCF_DOREDIRECT && !opt->srr)
107 ip_rt_send_redirect(skb);
108
109 skb->priority = rt_tos2priority(iph->tos);
110
111 return NF_HOOK(PF_INET, NF_IP_FORWARD, skb, skb->dev, rt->u.dst.dev,
112 ip_forward_finish);
113
114sr_failed:
115 /*
116 * Strict routing permits no gatewaying
117 */
118 icmp_send(skb, ICMP_DEST_UNREACH, ICMP_SR_FAILED, 0);
119 goto drop;
120
121too_many_hops:
122 /* Tell the sender its packet died... */
123 icmp_send(skb, ICMP_TIME_EXCEEDED, ICMP_EXC_TTL, 0);
124drop:
125 kfree_skb(skb);
126 return NET_RX_DROP;
127}