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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_conntrack_helper.h>
21#include <net/netfilter/nf_conntrack_expect.h>
22#include <linux/netfilter/nf_conntrack_irc.h>
23
24MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
25MODULE_DESCRIPTION("IRC (DCC) NAT helper");
26MODULE_LICENSE("GPL");
27MODULE_ALIAS("ip_nat_irc");
28
29static unsigned int help(struct sk_buff *skb,
30 enum ip_conntrack_info ctinfo,
31 unsigned int protoff,
32 unsigned int matchoff,
33 unsigned int matchlen,
34 struct nf_conntrack_expect *exp)
35{
36 char buffer[sizeof("4294967296 65635")];
37 u_int16_t port;
38 unsigned int ret;
39
40
41 exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
42 exp->dir = IP_CT_DIR_REPLY;
43 exp->expectfn = nf_nat_follow_master;
44
45
46 for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
47 int ret;
48
49 exp->tuple.dst.u.tcp.port = htons(port);
50 ret = nf_ct_expect_related(exp);
51 if (ret == 0)
52 break;
53 else if (ret != -EBUSY) {
54 port = 0;
55 break;
56 }
57 }
58
59 if (port == 0) {
60 nf_ct_helper_log(skb, exp->master, "all ports in use");
61 return NF_DROP;
62 }
63
64 ret = nf_nat_mangle_tcp_packet(skb, exp->master, ctinfo,
65 protoff, matchoff, matchlen, buffer,
66 strlen(buffer));
67 if (ret != NF_ACCEPT) {
68 nf_ct_helper_log(skb, exp->master, "cannot mangle packet");
69 nf_ct_unexpect_related(exp);
70 }
71 return ret;
72}
73
74static void __exit nf_nat_irc_fini(void)
75{
76 RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
77 synchronize_rcu();
78}
79
80static int __init nf_nat_irc_init(void)
81{
82 BUG_ON(nf_nat_irc_hook != NULL);
83 RCU_INIT_POINTER(nf_nat_irc_hook, help);
84 return 0;
85}
86
87
88static int warn_set(const char *val, struct kernel_param *kp)
89{
90 printk(KERN_INFO KBUILD_MODNAME
91 ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
92 return 0;
93}
94module_param_call(ports, warn_set, NULL, NULL, 0);
95
96module_init(nf_nat_irc_init);
97module_exit(nf_nat_irc_fini);
98