316 lines
8.8 KiB
C
316 lines
8.8 KiB
C
/* IRC extension for IP connection tracking, Version 1.21
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* (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
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* based on RR's ip_conntrack_ftp.c
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*
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* ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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**
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* Module load syntax:
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* insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS>
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* max_dcc_channels=n dcc_timeout=secs
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*
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* please give the ports of all IRC servers You wish to connect to.
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* If You don't specify ports, the default will be port 6667.
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* With max_dcc_channels you can define the maximum number of not
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* yet answered DCC channels per IRC session (default 8).
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* With dcc_timeout you can specify how long the system waits for
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* an expected DCC channel (default 300 seconds).
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*
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*/
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#include <linux/config.h>
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#include <linux/module.h>
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#include <linux/netfilter.h>
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#include <linux/ip.h>
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#include <net/checksum.h>
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#include <net/tcp.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#include <linux/netfilter_ipv4/ip_conntrack_irc.h>
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#include <linux/moduleparam.h>
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#define MAX_PORTS 8
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static int ports[MAX_PORTS];
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static int ports_c;
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static int max_dcc_channels = 8;
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static unsigned int dcc_timeout = 300;
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/* This is slow, but it's simple. --RR */
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static char *irc_buffer;
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static DEFINE_SPINLOCK(irc_buffer_lock);
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unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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unsigned int matchoff,
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unsigned int matchlen,
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struct ip_conntrack_expect *exp);
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EXPORT_SYMBOL_GPL(ip_nat_irc_hook);
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MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
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MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
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MODULE_LICENSE("GPL");
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module_param_array(ports, int, &ports_c, 0400);
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MODULE_PARM_DESC(ports, "port numbers of IRC servers");
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module_param(max_dcc_channels, int, 0400);
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MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session");
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module_param(dcc_timeout, int, 0400);
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MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
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static char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };
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#define MINMATCHLEN 5
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#if 0
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#define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \
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__FILE__, __FUNCTION__ , ## args)
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#else
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#define DEBUGP(format, args...)
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#endif
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static int parse_dcc(char *data, char *data_end, u_int32_t *ip,
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u_int16_t *port, char **ad_beg_p, char **ad_end_p)
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/* tries to get the ip_addr and port out of a dcc command
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return value: -1 on failure, 0 on success
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data pointer to first byte of DCC command data
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data_end pointer to last byte of dcc command data
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ip returns parsed ip of dcc command
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port returns parsed port of dcc command
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ad_beg_p returns pointer to first byte of addr data
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ad_end_p returns pointer to last byte of addr data */
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{
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/* at least 12: "AAAAAAAA P\1\n" */
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while (*data++ != ' ')
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if (data > data_end - 12)
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return -1;
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*ad_beg_p = data;
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*ip = simple_strtoul(data, &data, 10);
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/* skip blanks between ip and port */
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while (*data == ' ') {
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if (data >= data_end)
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return -1;
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data++;
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}
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*port = simple_strtoul(data, &data, 10);
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*ad_end_p = data;
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return 0;
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}
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static int help(struct sk_buff **pskb,
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struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
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{
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unsigned int dataoff;
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struct tcphdr _tcph, *th;
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char *data, *data_limit, *ib_ptr;
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int dir = CTINFO2DIR(ctinfo);
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struct ip_conntrack_expect *exp;
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u32 seq;
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u_int32_t dcc_ip;
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u_int16_t dcc_port;
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int i, ret = NF_ACCEPT;
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char *addr_beg_p, *addr_end_p;
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DEBUGP("entered\n");
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/* If packet is coming from IRC server */
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if (dir == IP_CT_DIR_REPLY)
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return NF_ACCEPT;
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/* Until there's been traffic both ways, don't look in packets. */
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if (ctinfo != IP_CT_ESTABLISHED
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&& ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
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DEBUGP("Conntrackinfo = %u\n", ctinfo);
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return NF_ACCEPT;
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}
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/* Not a full tcp header? */
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th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
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sizeof(_tcph), &_tcph);
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if (th == NULL)
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return NF_ACCEPT;
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/* No data? */
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dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4;
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if (dataoff >= (*pskb)->len)
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return NF_ACCEPT;
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spin_lock_bh(&irc_buffer_lock);
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ib_ptr = skb_header_pointer(*pskb, dataoff,
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(*pskb)->len - dataoff, irc_buffer);
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BUG_ON(ib_ptr == NULL);
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data = ib_ptr;
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data_limit = ib_ptr + (*pskb)->len - dataoff;
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/* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
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* 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
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while (data < (data_limit - (19 + MINMATCHLEN))) {
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if (memcmp(data, "\1DCC ", 5)) {
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data++;
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continue;
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}
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data += 5;
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/* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
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DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n",
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NIPQUAD(iph->saddr), ntohs(th->source),
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NIPQUAD(iph->daddr), ntohs(th->dest));
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for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
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if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
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/* no match */
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continue;
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}
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DEBUGP("DCC %s detected\n", dccprotos[i]);
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data += strlen(dccprotos[i]);
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/* we have at least
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* (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
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* data left (== 14/13 bytes) */
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if (parse_dcc((char *)data, data_limit, &dcc_ip,
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&dcc_port, &addr_beg_p, &addr_end_p)) {
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/* unable to parse */
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DEBUGP("unable to parse dcc command\n");
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continue;
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}
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DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n",
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HIPQUAD(dcc_ip), dcc_port);
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/* dcc_ip can be the internal OR external (NAT'ed) IP
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* Tiago Sousa <mirage@kaotik.org> */
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if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)
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&& ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) {
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if (net_ratelimit())
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printk(KERN_WARNING
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"Forged DCC command from "
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"%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
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NIPQUAD(ct->tuplehash[dir].tuple.src.ip),
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HIPQUAD(dcc_ip), dcc_port);
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continue;
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}
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exp = ip_conntrack_expect_alloc(ct);
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if (exp == NULL) {
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ret = NF_DROP;
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goto out;
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}
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/* save position of address in dcc string,
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* necessary for NAT */
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DEBUGP("tcph->seq = %u\n", th->seq);
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seq = ntohl(th->seq) + (addr_beg_p - ib_ptr);
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/* We refer to the reverse direction ("!dir")
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* tuples here, because we're expecting
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* something in the other * direction.
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* Doesn't matter unless NAT is happening. */
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exp->tuple = ((struct ip_conntrack_tuple)
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{ { 0, { 0 } },
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{ ct->tuplehash[!dir].tuple.dst.ip,
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{ .tcp = { htons(dcc_port) } },
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IPPROTO_TCP }});
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exp->mask = ((struct ip_conntrack_tuple)
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{ { 0, { 0 } },
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{ 0xFFFFFFFF, { .tcp = { 0xFFFF } }, 0xFF }});
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exp->expectfn = NULL;
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if (ip_nat_irc_hook)
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ret = ip_nat_irc_hook(pskb, ctinfo,
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addr_beg_p - ib_ptr,
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addr_end_p - addr_beg_p,
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exp);
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else if (ip_conntrack_expect_related(exp) != 0)
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ret = NF_DROP;
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ip_conntrack_expect_put(exp);
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goto out;
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} /* for .. NUM_DCCPROTO */
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} /* while data < ... */
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out:
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spin_unlock_bh(&irc_buffer_lock);
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return ret;
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}
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static struct ip_conntrack_helper irc_helpers[MAX_PORTS];
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static char irc_names[MAX_PORTS][10];
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static void fini(void);
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static int __init init(void)
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{
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int i, ret;
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struct ip_conntrack_helper *hlpr;
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char *tmpname;
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if (max_dcc_channels < 1) {
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printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");
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return -EBUSY;
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}
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if (dcc_timeout < 0) {
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printk("ip_conntrack_irc: dcc_timeout must be a positive integer\n");
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return -EBUSY;
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}
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irc_buffer = kmalloc(65536, GFP_KERNEL);
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if (!irc_buffer)
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return -ENOMEM;
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/* If no port given, default to standard irc port */
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if (ports_c == 0)
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ports[ports_c++] = IRC_PORT;
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for (i = 0; i < ports_c; i++) {
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hlpr = &irc_helpers[i];
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hlpr->tuple.src.u.tcp.port = htons(ports[i]);
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hlpr->tuple.dst.protonum = IPPROTO_TCP;
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hlpr->mask.src.u.tcp.port = 0xFFFF;
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hlpr->mask.dst.protonum = 0xFF;
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hlpr->max_expected = max_dcc_channels;
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hlpr->timeout = dcc_timeout;
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hlpr->me = THIS_MODULE;
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hlpr->help = help;
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tmpname = &irc_names[i][0];
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if (ports[i] == IRC_PORT)
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sprintf(tmpname, "irc");
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else
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sprintf(tmpname, "irc-%d", i);
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hlpr->name = tmpname;
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DEBUGP("port #%d: %d\n", i, ports[i]);
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ret = ip_conntrack_helper_register(hlpr);
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if (ret) {
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printk("ip_conntrack_irc: ERROR registering port %d\n",
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ports[i]);
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fini();
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return -EBUSY;
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}
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}
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return 0;
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}
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/* This function is intentionally _NOT_ defined as __exit, because
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* it is needed by the init function */
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static void fini(void)
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{
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int i;
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for (i = 0; i < ports_c; i++) {
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DEBUGP("unregistering port %d\n",
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ports[i]);
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ip_conntrack_helper_unregister(&irc_helpers[i]);
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}
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kfree(irc_buffer);
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}
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module_init(init);
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module_exit(fini);
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