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869f37d8 PM |
1 | /* IRC extension for TCP NAT alteration. |
2 | * | |
3 | * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org> | |
4 | * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation | |
5 | * based on a copy of RR's ip_nat_ftp.c | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | */ | |
12 | ||
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 | ||
25 | #if 0 | |
26 | #define DEBUGP printk | |
27 | #else | |
28 | #define DEBUGP(format, args...) | |
29 | #endif | |
30 | ||
31 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); | |
32 | MODULE_DESCRIPTION("IRC (DCC) NAT helper"); | |
33 | MODULE_LICENSE("GPL"); | |
34 | MODULE_ALIAS("ip_nat_irc"); | |
35 | ||
36 | static unsigned int help(struct sk_buff **pskb, | |
37 | enum ip_conntrack_info ctinfo, | |
38 | unsigned int matchoff, | |
39 | unsigned int matchlen, | |
40 | struct nf_conntrack_expect *exp) | |
41 | { | |
42 | char buffer[sizeof("4294967296 65635")]; | |
43 | u_int32_t ip; | |
44 | u_int16_t port; | |
45 | unsigned int ret; | |
46 | ||
47 | DEBUGP("IRC_NAT: info (seq %u + %u) in %u\n", | |
48 | expect->seq, exp_irc_info->len, ntohl(tcph->seq)); | |
49 | ||
50 | /* Reply comes from server. */ | |
51 | exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; | |
52 | exp->dir = IP_CT_DIR_REPLY; | |
53 | exp->expectfn = nf_nat_follow_master; | |
54 | ||
55 | /* Try to get same port: if not, try to change it. */ | |
56 | for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) { | |
57 | exp->tuple.dst.u.tcp.port = htons(port); | |
58 | if (nf_conntrack_expect_related(exp) == 0) | |
59 | break; | |
60 | } | |
61 | ||
62 | if (port == 0) | |
63 | return NF_DROP; | |
64 | ||
65 | ip = ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3.ip); | |
66 | sprintf(buffer, "%u %u", ip, port); | |
67 | DEBUGP("nf_nat_irc: inserting '%s' == %u.%u.%u.%u, port %u\n", | |
68 | buffer, NIPQUAD(ip), port); | |
69 | ||
70 | ret = nf_nat_mangle_tcp_packet(pskb, exp->master, ctinfo, | |
71 | matchoff, matchlen, buffer, | |
72 | strlen(buffer)); | |
73 | if (ret != NF_ACCEPT) | |
74 | nf_conntrack_unexpect_related(exp); | |
75 | return ret; | |
76 | } | |
77 | ||
78 | static void __exit nf_nat_irc_fini(void) | |
79 | { | |
80 | rcu_assign_pointer(nf_nat_irc_hook, NULL); | |
81 | synchronize_rcu(); | |
82 | } | |
83 | ||
84 | static int __init nf_nat_irc_init(void) | |
85 | { | |
86 | BUG_ON(rcu_dereference(nf_nat_irc_hook)); | |
87 | rcu_assign_pointer(nf_nat_irc_hook, help); | |
88 | return 0; | |
89 | } | |
90 | ||
91 | /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */ | |
92 | static int warn_set(const char *val, struct kernel_param *kp) | |
93 | { | |
94 | printk(KERN_INFO KBUILD_MODNAME | |
95 | ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n"); | |
96 | return 0; | |
97 | } | |
98 | module_param_call(ports, warn_set, NULL, NULL, 0); | |
99 | ||
100 | module_init(nf_nat_irc_init); | |
101 | module_exit(nf_nat_irc_fini); |