1 /* IRC extension for TCP NAT alteration.
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
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.
13 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15 #include <linux/module.h>
16 #include <linux/moduleparam.h>
17 #include <linux/tcp.h>
18 #include <linux/kernel.h>
20 #include <net/netfilter/nf_nat.h>
21 #include <net/netfilter/nf_nat_helper.h>
22 #include <net/netfilter/nf_conntrack_helper.h>
23 #include <net/netfilter/nf_conntrack_expect.h>
24 #include <linux/netfilter/nf_conntrack_irc.h>
26 #define NAT_HELPER_NAME "irc"
28 MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
29 MODULE_DESCRIPTION("IRC (DCC) NAT helper");
30 MODULE_LICENSE("GPL");
31 MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME);
33 static struct nf_conntrack_nat_helper nat_helper_irc =
34 NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME);
36 static unsigned int help(struct sk_buff *skb,
37 enum ip_conntrack_info ctinfo,
39 unsigned int matchoff,
40 unsigned int matchlen,
41 struct nf_conntrack_expect *exp)
43 char buffer[sizeof("4294967296 65635")];
44 struct nf_conn *ct = exp->master;
45 union nf_inet_addr newaddr;
48 /* Reply comes from server. */
49 newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3;
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;
55 /* Try to get same port: if not, try to change it. */
56 for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
59 exp->tuple.dst.u.tcp.port = htons(port);
60 ret = nf_ct_expect_related(exp);
63 else if (ret != -EBUSY) {
70 nf_ct_helper_log(skb, ct, "all ports in use");
74 /* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
75 * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
76 * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
77 * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
78 * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
80 * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
81 * 255.255.255.255==4294967296, 10 digits)
82 * P: bound port (min 1 d, max 5d (65635))
83 * F: filename (min 1 d )
85 * 0x01, \n: terminators
87 /* AAA = "us", ie. where server normally talks to. */
88 snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port);
89 pr_debug("inserting '%s' == %pI4, port %u\n",
90 buffer, &newaddr.ip, port);
92 if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
93 matchlen, buffer, strlen(buffer))) {
94 nf_ct_helper_log(skb, ct, "cannot mangle packet");
95 nf_ct_unexpect_related(exp);
102 static void __exit nf_nat_irc_fini(void)
104 nf_nat_helper_unregister(&nat_helper_irc);
105 RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
109 static int __init nf_nat_irc_init(void)
111 BUG_ON(nf_nat_irc_hook != NULL);
112 nf_nat_helper_register(&nat_helper_irc);
113 RCU_INIT_POINTER(nf_nat_irc_hook, help);
117 /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
118 static int warn_set(const char *val, const struct kernel_param *kp)
120 pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
123 module_param_call(ports, warn_set, NULL, NULL, 0);
125 module_init(nf_nat_irc_init);
126 module_exit(nf_nat_irc_fini);