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13#include <linux/module.h>
14#include <linux/moduleparam.h>
15#include <linux/tcp.h>
16#include <linux/kernel.h>
17
18#include <net/netfilter/nf_nat.h>
19#include <net/netfilter/nf_nat_helper.h>
20#include <net/netfilter/nf_nat_rule.h>
21#include <net/netfilter/nf_conntrack_helper.h>
22#include <net/netfilter/nf_conntrack_expect.h>
23#include <linux/netfilter/nf_conntrack_irc.h>
24
25MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
26MODULE_DESCRIPTION("IRC (DCC) NAT helper");
27MODULE_LICENSE("GPL");
28MODULE_ALIAS("ip_nat_irc");
29
30static unsigned int help(struct sk_buff *skb,
31 enum ip_conntrack_info ctinfo,
32 unsigned int matchoff,
33 unsigned int matchlen,
34 struct nf_conntrack_expect *exp)
35{
36 char buffer[sizeof("4294967296 65635")];
37 u_int32_t ip;
38 u_int16_t port;
39 unsigned int ret;
40
41
42 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
43 exp->dir = IP_CT_DIR_REPLY;
44 exp->expectfn = nf_nat_follow_master;
45
46
47 for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
48 int ret;
49
50 exp->tuple.dst.u.tcp.port = htons(port);
51 ret = nf_ct_expect_related(exp);
52 if (ret == 0)
53 break;
54 else if (ret != -EBUSY) {
55 port = 0;
56 break;
57 }
58 }
59
60 if (port == 0)
61 return NF_DROP;
62
63 ip = ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip);
64 sprintf(buffer, "%u %u", ip, port);
65 pr_debug("nf_nat_irc: inserting '%s' == %pI4, port %u\n",
66 buffer, &ip, port);
67
68 ret = nf_nat_mangle_tcp_packet(skb, exp->master, ctinfo,
69 matchoff, matchlen, buffer,
70 strlen(buffer));
71 if (ret != NF_ACCEPT)
72 nf_ct_unexpect_related(exp);
73 return ret;
74}
75
76static void __exit nf_nat_irc_fini(void)
77{
78 rcu_assign_pointer(nf_nat_irc_hook, NULL);
79 synchronize_rcu();
80}
81
82static int __init nf_nat_irc_init(void)
83{
84 BUG_ON(nf_nat_irc_hook != NULL);
85 rcu_assign_pointer(nf_nat_irc_hook, help);
86 return 0;
87}
88
89
90static int warn_set(const char *val, struct kernel_param *kp)
91{
92 printk(KERN_INFO KBUILD_MODNAME
93 ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
94 return 0;
95}
96module_param_call(ports, warn_set, NULL, NULL, 0);
97
98module_init(nf_nat_irc_init);
99module_exit(nf_nat_irc_fini);
100