/* IRC extension for IP connection tracking, Version 1.21 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org> * based on RR's ip_conntrack_ftp.c	 * * ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 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. ** *	Module load syntax: * 	insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS> *			    max_dcc_channels=n dcc_timeout=secs *	 * 	please give the ports of all IRC servers You wish to connect to. *	If You don't specify ports, the default will be port 6667. *	With max_dcc_channels you can define the maximum number of not *	yet answered DCC channels per IRC session (default 8). *	With dcc_timeout you can specify how long the system waits for  *	an expected DCC channel (default 300 seconds). * */#include <linux/config.h>#include <linux/module.h>#include <linux/netfilter.h>#include <linux/ip.h>#include <net/checksum.h>#include <net/tcp.h>#include <linux/netfilter_ipv4/lockhelp.h>#include <linux/netfilter_ipv4/ip_conntrack_helper.h>#include <linux/netfilter_ipv4/ip_conntrack_irc.h>#define MAX_PORTS 8static int ports[MAX_PORTS];static int ports_c;static int max_dcc_channels = 8;static unsigned int dcc_timeout = 300;/* This is slow, but it's simple. --RR */static char irc_buffer[65536];MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");MODULE_LICENSE("GPL");MODULE_PARM(ports, "1-" __MODULE_STRING(MAX_PORTS) "i");MODULE_PARM_DESC(ports, "port numbers of IRC servers");MODULE_PARM(max_dcc_channels, "i");MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session");MODULE_PARM(dcc_timeout, "i");MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");static char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };#define MINMATCHLEN	5DECLARE_LOCK(ip_irc_lock);struct module *ip_conntrack_irc = THIS_MODULE;#if 0#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \                                       __FILE__, __FUNCTION__ , ## args)#else#define DEBUGP(format, args...)#endifint parse_dcc(char *data, char *data_end, u_int32_t * ip, u_int16_t * port,	      char **ad_beg_p, char **ad_end_p)/* tries to get the ip_addr and port out of a dcc command   return value: -1 on failure, 0 on success 	data		pointer to first byte of DCC command data	data_end	pointer to last byte of dcc command data	ip		returns parsed ip of dcc command	port		returns parsed port of dcc command	ad_beg_p	returns pointer to first byte of addr data	ad_end_p	returns pointer to last byte of addr data */{	/* at least 12: "AAAAAAAA P\1\n" */	while (*data++ != ' ')		if (data > data_end - 12)			return -1;	*ad_beg_p = data;	*ip = simple_strtoul(data, &data, 10);	/* skip blanks between ip and port */	while (*data == ' ') {		if (data >= data_end) 			return -1;		data++;	}	*port = simple_strtoul(data, &data, 10);	*ad_end_p = data;	return 0;}static int help(struct sk_buff *skb,		struct ip_conntrack *ct, enum ip_conntrack_info ctinfo){	unsigned int dataoff;	struct tcphdr tcph;	char *data, *data_limit;	int dir = CTINFO2DIR(ctinfo);	struct ip_conntrack_expect *exp;	struct ip_ct_irc_expect *exp_irc_info = NULL;	u_int32_t dcc_ip;	u_int16_t dcc_port;	int i;	char *addr_beg_p, *addr_end_p;	DEBUGP("entered\n");	/* If packet is coming from IRC server */	if (dir == IP_CT_DIR_REPLY)		return NF_ACCEPT;	/* Until there's been traffic both ways, don't look in packets. */	if (ctinfo != IP_CT_ESTABLISHED	    && ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {		DEBUGP("Conntrackinfo = %u\n", ctinfo);		return NF_ACCEPT;	}	/* Not a full tcp header? */	if (skb_copy_bits(skb, skb->nh.iph->ihl*4, &tcph, sizeof(tcph)) != 0)		return NF_ACCEPT;	/* No data? */	dataoff = skb->nh.iph->ihl*4 + tcph.doff*4;	if (dataoff >= skb->len)		return NF_ACCEPT;	LOCK_BH(&ip_irc_lock);	skb_copy_bits(skb, dataoff, irc_buffer, skb->len - dataoff);	data = irc_buffer;	data_limit = irc_buffer + skb->len - dataoff;	/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24	 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */	while (data < (data_limit - (19 + MINMATCHLEN))) {		if (memcmp(data, "\1DCC ", 5)) {			data++;			continue;		}		data += 5;		/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */		DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n",			NIPQUAD(iph->saddr), ntohs(tcph.source),			NIPQUAD(iph->daddr), ntohs(tcph.dest));		for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {			if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {				/* no match */				continue;			}			DEBUGP("DCC %s detected\n", dccprotos[i]);			data += strlen(dccprotos[i]);			/* we have at least 			 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid			 * data left (== 14/13 bytes) */			if (parse_dcc((char *)data, data_limit, &dcc_ip,				       &dcc_port, &addr_beg_p, &addr_end_p)) {				/* unable to parse */				DEBUGP("unable to parse dcc command\n");				continue;			}			DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n",				HIPQUAD(dcc_ip), dcc_port);			/* dcc_ip can be the internal OR external (NAT'ed) IP			 * Tiago Sousa <mirage@kaotik.org> */			if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)			    && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) {				if (net_ratelimit())					printk(KERN_WARNING						"Forged DCC command from "						"%u.%u.%u.%u: %u.%u.%u.%u:%u\n",				NIPQUAD(ct->tuplehash[dir].tuple.src.ip),						HIPQUAD(dcc_ip), dcc_port);				continue;			}			exp = ip_conntrack_expect_alloc();			if (exp == NULL)				goto out;			exp_irc_info = &exp->help.exp_irc_info;			/* save position of address in dcc string,			 * necessary for NAT */			DEBUGP("tcph->seq = %u\n", tcph.seq);			exp->seq = ntohl(tcph.seq) + (addr_beg_p - irc_buffer);			exp_irc_info->len = (addr_end_p - addr_beg_p);			exp_irc_info->port = dcc_port;			DEBUGP("wrote info seq=%u (ofs=%u), len=%d\n",				exp->seq, (addr_end_p - _data), exp_irc_info->len);			exp->tuple = ((struct ip_conntrack_tuple)				{ { 0, { 0 } },				  { ct->tuplehash[dir].tuple.src.ip, { .tcp = { htons(dcc_port) } },				    IPPROTO_TCP }});			exp->mask = ((struct ip_conntrack_tuple)				{ { 0, { 0 } },				  { 0xFFFFFFFF, { .tcp = { 0xFFFF } }, 0xFFFF }});			exp->expectfn = NULL;			DEBUGP("expect_related %u.%u.%u.%u:%u-%u.%u.%u.%u:%u\n",				NIPQUAD(exp->tuple.src.ip),				ntohs(exp->tuple.src.u.tcp.port),				NIPQUAD(exp->tuple.dst.ip),				ntohs(exp->tuple.dst.u.tcp.port));			ip_conntrack_expect_related(exp, ct);			goto out;		} /* for .. NUM_DCCPROTO */	} /* while data < ... */ out:	UNLOCK_BH(&ip_irc_lock);	return NF_ACCEPT;}static struct ip_conntrack_helper irc_helpers[MAX_PORTS];static char irc_names[MAX_PORTS][10];static void fini(void);static int __init init(void){	int i, ret;	struct ip_conntrack_helper *hlpr;	char *tmpname;	if (max_dcc_channels < 1) {		printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");		return -EBUSY;	}	if (dcc_timeout < 0) {		printk("ip_conntrack_irc: dcc_timeout must be a positive integer\n");		return -EBUSY;	}		/* If no port given, default to standard irc port */	if (ports[0] == 0)		ports[0] = IRC_PORT;	for (i = 0; (i < MAX_PORTS) && ports[i]; i++) {		hlpr = &irc_helpers[i];		hlpr->tuple.src.u.tcp.port = htons(ports[i]);		hlpr->tuple.dst.protonum = IPPROTO_TCP;		hlpr->mask.src.u.tcp.port = 0xFFFF;		hlpr->mask.dst.protonum = 0xFFFF;		hlpr->max_expected = max_dcc_channels;		hlpr->timeout = dcc_timeout;		hlpr->flags = IP_CT_HELPER_F_REUSE_EXPECT;		hlpr->me = ip_conntrack_irc;		hlpr->help = help;		tmpname = &irc_names[i][0];		if (ports[i] == IRC_PORT)			sprintf(tmpname, "irc");		else			sprintf(tmpname, "irc-%d", i);		hlpr->name = tmpname;		DEBUGP("port #%d: %d\n", i, ports[i]);		ret = ip_conntrack_helper_register(hlpr);		if (ret) {			printk("ip_conntrack_irc: ERROR registering port %d\n",				ports[i]);			fini();			return -EBUSY;		}		ports_c++;	}	return 0;}/* This function is intentionally _NOT_ defined as __exit, because  * it is needed by the init function */static void fini(void){	int i;	for (i = 0; i < ports_c; i++) {		DEBUGP("unregistering port %d\n",		       ports[i]);		ip_conntrack_helper_unregister(&irc_helpers[i]);	}}PROVIDES_CONNTRACK(irc);EXPORT_SYMBOL(ip_irc_lock);module_init(init);module_exit(fini);