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1da177e4 LT |
1 | /* IRC extension for TCP NAT alteration. |
2 | * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org> | |
3 | * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation | |
4 | * based on a copy of RR's ip_nat_ftp.c | |
5 | * | |
6 | * ip_nat_irc.c,v 1.16 2001/12/06 07:42:10 laforge Exp | |
7 | * | |
8 | * This program is free software; you can redistribute it and/or | |
9 | * modify it under the terms of the GNU General Public License | |
10 | * as published by the Free Software Foundation; either version | |
11 | * 2 of the License, or (at your option) any later version. | |
12 | */ | |
13 | ||
14 | #include <linux/module.h> | |
15 | #include <linux/netfilter_ipv4.h> | |
16 | #include <linux/ip.h> | |
17 | #include <linux/tcp.h> | |
18 | #include <linux/kernel.h> | |
19 | #include <net/tcp.h> | |
20 | #include <linux/netfilter_ipv4/ip_nat.h> | |
21 | #include <linux/netfilter_ipv4/ip_nat_helper.h> | |
22 | #include <linux/netfilter_ipv4/ip_nat_rule.h> | |
23 | #include <linux/netfilter_ipv4/ip_conntrack_irc.h> | |
24 | #include <linux/netfilter_ipv4/ip_conntrack_helper.h> | |
25 | #include <linux/moduleparam.h> | |
26 | ||
27 | #if 0 | |
28 | #define DEBUGP printk | |
29 | #else | |
30 | #define DEBUGP(format, args...) | |
31 | #endif | |
32 | ||
33 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); | |
34 | MODULE_DESCRIPTION("IRC (DCC) NAT helper"); | |
35 | MODULE_LICENSE("GPL"); | |
36 | ||
37 | static unsigned int help(struct sk_buff **pskb, | |
38 | enum ip_conntrack_info ctinfo, | |
39 | unsigned int matchoff, | |
40 | unsigned int matchlen, | |
41 | struct ip_conntrack_expect *exp) | |
42 | { | |
43 | u_int16_t port; | |
44 | unsigned int ret; | |
45 | ||
46 | /* "4294967296 65635 " */ | |
47 | char buffer[18]; | |
48 | ||
49 | DEBUGP("IRC_NAT: info (seq %u + %u) in %u\n", | |
50 | expect->seq, exp_irc_info->len, | |
51 | ntohl(tcph->seq)); | |
52 | ||
53 | /* Reply comes from server. */ | |
54 | exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; | |
55 | exp->dir = IP_CT_DIR_REPLY; | |
56 | ||
57 | /* When you see the packet, we need to NAT it the same as the | |
58 | * this one. */ | |
59 | exp->expectfn = ip_nat_follow_master; | |
60 | ||
61 | /* Try to get same port: if not, try to change it. */ | |
62 | for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) { | |
63 | exp->tuple.dst.u.tcp.port = htons(port); | |
64 | if (ip_conntrack_expect_related(exp) == 0) | |
65 | break; | |
66 | } | |
67 | ||
4acdbdbe | 68 | if (port == 0) |
1da177e4 | 69 | return NF_DROP; |
1da177e4 LT |
70 | |
71 | /* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27 | |
72 | * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28 | |
73 | * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26 | |
74 | * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26 | |
75 | * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27 | |
76 | * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits, | |
77 | * 255.255.255.255==4294967296, 10 digits) | |
78 | * P: bound port (min 1 d, max 5d (65635)) | |
79 | * F: filename (min 1 d ) | |
80 | * S: size (min 1 d ) | |
81 | * 0x01, \n: terminators | |
82 | */ | |
83 | ||
84 | /* AAA = "us", ie. where server normally talks to. */ | |
85 | sprintf(buffer, "%u %u", | |
86 | ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip), | |
87 | port); | |
88 | DEBUGP("ip_nat_irc: Inserting '%s' == %u.%u.%u.%u, port %u\n", | |
89 | buffer, NIPQUAD(exp->tuple.src.ip), port); | |
90 | ||
91 | ret = ip_nat_mangle_tcp_packet(pskb, exp->master, ctinfo, | |
92 | matchoff, matchlen, buffer, | |
93 | strlen(buffer)); | |
94 | if (ret != NF_ACCEPT) | |
95 | ip_conntrack_unexpect_related(exp); | |
96 | return ret; | |
97 | } | |
98 | ||
65b4b4e8 | 99 | static void __exit ip_nat_irc_fini(void) |
1da177e4 LT |
100 | { |
101 | ip_nat_irc_hook = NULL; | |
102 | /* Make sure noone calls it, meanwhile. */ | |
103 | synchronize_net(); | |
104 | } | |
105 | ||
65b4b4e8 | 106 | static int __init ip_nat_irc_init(void) |
1da177e4 LT |
107 | { |
108 | BUG_ON(ip_nat_irc_hook); | |
109 | ip_nat_irc_hook = help; | |
110 | return 0; | |
111 | } | |
112 | ||
113 | /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */ | |
114 | static int warn_set(const char *val, struct kernel_param *kp) | |
115 | { | |
367cb704 | 116 | printk(KERN_INFO KBUILD_MODNAME |
1da177e4 LT |
117 | ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n"); |
118 | return 0; | |
119 | } | |
120 | module_param_call(ports, warn_set, NULL, NULL, 0); | |
121 | ||
65b4b4e8 AM |
122 | module_init(ip_nat_irc_init); |
123 | module_exit(ip_nat_irc_fini); |