/* IRC extension for TCP NAT alteration. * (C) 2000-2001 by Harald Welte * (C) 2004 Rusty Russell IBM Corporation * based on a copy of RR's ip_nat_ftp.c * * ip_nat_irc.c,v 1.16 2001/12/06 07:42:10 laforge Exp * * 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 #include #include #include #include #include #include #include #include #include #include #include #if 0 #define DEBUGP printk #else #define DEBUGP(format, args...) #endif MODULE_AUTHOR("Harald Welte "); MODULE_DESCRIPTION("IRC (DCC) NAT helper"); MODULE_LICENSE("GPL"); static unsigned int help(struct sk_buff **pskb, enum ip_conntrack_info ctinfo, unsigned int matchoff, unsigned int matchlen, struct ip_conntrack_expect *exp) { u_int16_t port; unsigned int ret; /* "4294967296 65635 " */ char buffer[18]; DEBUGP("IRC_NAT: info (seq %u + %u) in %u\n", expect->seq, exp_irc_info->len, ntohl(tcph->seq)); /* Reply comes from server. */ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; exp->dir = IP_CT_DIR_REPLY; /* When you see the packet, we need to NAT it the same as the * this one. */ exp->expectfn = ip_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++) { exp->tuple.dst.u.tcp.port = htons(port); if (ip_conntrack_expect_related(exp) == 0) break; } if (port == 0) 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. */ sprintf(buffer, "%u %u", ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip), port); DEBUGP("ip_nat_irc: Inserting '%s' == %u.%u.%u.%u, port %u\n", buffer, NIPQUAD(exp->tuple.src.ip), port); ret = ip_nat_mangle_tcp_packet(pskb, exp->master, ctinfo, matchoff, matchlen, buffer, strlen(buffer)); if (ret != NF_ACCEPT) ip_conntrack_unexpect_related(exp); return ret; } static void __exit ip_nat_irc_fini(void) { ip_nat_irc_hook = NULL; /* Make sure noone calls it, meanwhile. */ synchronize_net(); } static int __init ip_nat_irc_init(void) { BUG_ON(ip_nat_irc_hook); ip_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(ip_nat_irc_init); module_exit(ip_nat_irc_fini);