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- /* IRC extension for TCP NAT alteration.
- *
- * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
- * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
- * based on a copy of RR's ip_nat_ftp.c
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
- #include <linux/module.h>
- #include <linux/moduleparam.h>
- #include <linux/tcp.h>
- #include <linux/kernel.h>
- #include <net/netfilter/nf_nat.h>
- #include <net/netfilter/nf_nat_helper.h>
- #include <net/netfilter/nf_conntrack_helper.h>
- #include <net/netfilter/nf_conntrack_expect.h>
- #include <linux/netfilter/nf_conntrack_irc.h>
- MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
- MODULE_DESCRIPTION("IRC (DCC) NAT helper");
- MODULE_LICENSE("GPL");
- MODULE_ALIAS("ip_nat_irc");
- static unsigned int help(struct sk_buff *skb,
- enum ip_conntrack_info ctinfo,
- unsigned int protoff,
- unsigned int matchoff,
- unsigned int matchlen,
- struct nf_conntrack_expect *exp)
- {
- char buffer[sizeof("4294967296 65635")];
- struct nf_conn *ct = exp->master;
- union nf_inet_addr newaddr;
- u_int16_t port;
- unsigned int ret;
- /* Reply comes from server. */
- newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3;
- exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
- exp->dir = IP_CT_DIR_REPLY;
- exp->expectfn = nf_nat_follow_master;
- /* Try to get same port: if not, try to change it. */
- for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
- int ret;
- exp->tuple.dst.u.tcp.port = htons(port);
- ret = nf_ct_expect_related(exp);
- if (ret == 0)
- break;
- else if (ret != -EBUSY) {
- port = 0;
- break;
- }
- }
- if (port == 0) {
- nf_ct_helper_log(skb, ct, "all ports in use");
- return NF_DROP;
- }
- /* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
- * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
- * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
- * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
- * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
- *
- * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
- * 255.255.255.255==4294967296, 10 digits)
- * P: bound port (min 1 d, max 5d (65635))
- * F: filename (min 1 d )
- * S: size (min 1 d )
- * 0x01, \n: terminators
- */
- /* AAA = "us", ie. where server normally talks to. */
- snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port);
- pr_debug("nf_nat_irc: inserting '%s' == %pI4, port %u\n",
- buffer, &newaddr.ip, port);
- ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
- matchlen, buffer, strlen(buffer));
- if (ret != NF_ACCEPT) {
- nf_ct_helper_log(skb, ct, "cannot mangle packet");
- nf_ct_unexpect_related(exp);
- }
- return ret;
- }
- static void __exit nf_nat_irc_fini(void)
- {
- RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
- synchronize_rcu();
- }
- static int __init nf_nat_irc_init(void)
- {
- BUG_ON(nf_nat_irc_hook != NULL);
- RCU_INIT_POINTER(nf_nat_irc_hook, help);
- return 0;
- }
- /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
- static int warn_set(const char *val, struct kernel_param *kp)
- {
- printk(KERN_INFO KBUILD_MODNAME
- ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
- return 0;
- }
- module_param_call(ports, warn_set, NULL, NULL, 0);
- module_init(nf_nat_irc_init);
- module_exit(nf_nat_irc_fini);
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