1 /* IRC extension for IP connection tracking, Version 1.21
2 * (C) 2000-2002 by Harald Welte <laforge@gnumonks.org>
3 * based on RR's ip_conntrack_ftp.c
5 * ip_conntrack_irc.c,v 1.21 2002/02/05 14:49:26 laforge Exp
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 * insmod ip_conntrack_irc.o ports=port1,port2,...port<MAX_PORTS>
14 * max_dcc_channels=n dcc_timeout=secs
16 * please give the ports of all IRC servers You wish to connect to.
17 * If You don't specify ports, the default will be port 6667.
18 * With max_dcc_channels you can define the maximum number of not
19 * yet answered DCC channels per IRC session (default 8).
20 * With dcc_timeout you can specify how long the system waits for
21 * an expected DCC channel (default 300 seconds).
25 #include <linux/module.h>
26 #include <linux/netfilter.h>
28 #include <net/checksum.h>
31 #include <linux/netfilter_ipv4/ip_conntrack_helper.h>
32 #include <linux/netfilter_ipv4/ip_conntrack_irc.h>
33 #include <linux/moduleparam.h>
36 static unsigned short ports[MAX_PORTS];
38 static unsigned int max_dcc_channels = 8;
39 static unsigned int dcc_timeout = 300;
40 /* This is slow, but it's simple. --RR */
41 static char *irc_buffer;
42 static DEFINE_SPINLOCK(irc_buffer_lock);
44 unsigned int (*ip_nat_irc_hook)(struct sk_buff **pskb,
45 enum ip_conntrack_info ctinfo,
46 unsigned int matchoff,
47 unsigned int matchlen,
48 struct ip_conntrack_expect *exp);
49 EXPORT_SYMBOL_GPL(ip_nat_irc_hook);
51 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
52 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
53 MODULE_LICENSE("GPL");
54 module_param_array(ports, ushort, &ports_c, 0400);
55 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
56 module_param(max_dcc_channels, uint, 0400);
57 MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per IRC session");
58 module_param(dcc_timeout, uint, 0400);
59 MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
61 static const char *dccprotos[] = { "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT " };
65 #define DEBUGP(format, args...) printk(KERN_DEBUG "%s:%s:" format, \
66 __FILE__, __FUNCTION__ , ## args)
68 #define DEBUGP(format, args...)
71 static int parse_dcc(char *data, char *data_end, u_int32_t *ip,
72 u_int16_t *port, char **ad_beg_p, char **ad_end_p)
73 /* tries to get the ip_addr and port out of a dcc command
74 return value: -1 on failure, 0 on success
75 data pointer to first byte of DCC command data
76 data_end pointer to last byte of dcc command data
77 ip returns parsed ip of dcc command
78 port returns parsed port of dcc command
79 ad_beg_p returns pointer to first byte of addr data
80 ad_end_p returns pointer to last byte of addr data */
83 /* at least 12: "AAAAAAAA P\1\n" */
84 while (*data++ != ' ')
85 if (data > data_end - 12)
89 *ip = simple_strtoul(data, &data, 10);
91 /* skip blanks between ip and port */
92 while (*data == ' ') {
98 *port = simple_strtoul(data, &data, 10);
104 static int help(struct sk_buff **pskb,
105 struct ip_conntrack *ct, enum ip_conntrack_info ctinfo)
107 unsigned int dataoff;
108 struct tcphdr _tcph, *th;
109 char *data, *data_limit, *ib_ptr;
110 int dir = CTINFO2DIR(ctinfo);
111 struct ip_conntrack_expect *exp;
115 int i, ret = NF_ACCEPT;
116 char *addr_beg_p, *addr_end_p;
120 /* If packet is coming from IRC server */
121 if (dir == IP_CT_DIR_REPLY)
124 /* Until there's been traffic both ways, don't look in packets. */
125 if (ctinfo != IP_CT_ESTABLISHED
126 && ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
127 DEBUGP("Conntrackinfo = %u\n", ctinfo);
131 /* Not a full tcp header? */
132 th = skb_header_pointer(*pskb, (*pskb)->nh.iph->ihl*4,
133 sizeof(_tcph), &_tcph);
138 dataoff = (*pskb)->nh.iph->ihl*4 + th->doff*4;
139 if (dataoff >= (*pskb)->len)
142 spin_lock_bh(&irc_buffer_lock);
143 ib_ptr = skb_header_pointer(*pskb, dataoff,
144 (*pskb)->len - dataoff, irc_buffer);
145 BUG_ON(ib_ptr == NULL);
148 data_limit = ib_ptr + (*pskb)->len - dataoff;
150 /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
151 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
152 while (data < (data_limit - (19 + MINMATCHLEN))) {
153 if (memcmp(data, "\1DCC ", 5)) {
159 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
161 DEBUGP("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u...\n",
162 NIPQUAD(iph->saddr), ntohs(th->source),
163 NIPQUAD(iph->daddr), ntohs(th->dest));
165 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
166 if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
171 DEBUGP("DCC %s detected\n", dccprotos[i]);
172 data += strlen(dccprotos[i]);
174 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
175 * data left (== 14/13 bytes) */
176 if (parse_dcc((char *)data, data_limit, &dcc_ip,
177 &dcc_port, &addr_beg_p, &addr_end_p)) {
178 /* unable to parse */
179 DEBUGP("unable to parse dcc command\n");
182 DEBUGP("DCC bound ip/port: %u.%u.%u.%u:%u\n",
183 HIPQUAD(dcc_ip), dcc_port);
185 /* dcc_ip can be the internal OR external (NAT'ed) IP
186 * Tiago Sousa <mirage@kaotik.org> */
187 if (ct->tuplehash[dir].tuple.src.ip != htonl(dcc_ip)
188 && ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip != htonl(dcc_ip)) {
191 "Forged DCC command from "
192 "%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
193 NIPQUAD(ct->tuplehash[dir].tuple.src.ip),
194 HIPQUAD(dcc_ip), dcc_port);
199 exp = ip_conntrack_expect_alloc(ct);
205 /* save position of address in dcc string,
206 * necessary for NAT */
207 DEBUGP("tcph->seq = %u\n", th->seq);
208 seq = ntohl(th->seq) + (addr_beg_p - ib_ptr);
210 /* We refer to the reverse direction ("!dir")
211 * tuples here, because we're expecting
212 * something in the other * direction.
213 * Doesn't matter unless NAT is happening. */
214 exp->tuple = ((struct ip_conntrack_tuple)
216 { ct->tuplehash[!dir].tuple.dst.ip,
217 { .tcp = { htons(dcc_port) } },
219 exp->mask = ((struct ip_conntrack_tuple)
221 { 0xFFFFFFFF, { .tcp = { 0xFFFF } }, 0xFF }});
222 exp->expectfn = NULL;
225 ret = ip_nat_irc_hook(pskb, ctinfo,
227 addr_end_p - addr_beg_p,
229 else if (ip_conntrack_expect_related(exp) != 0)
231 ip_conntrack_expect_put(exp);
233 } /* for .. NUM_DCCPROTO */
234 } /* while data < ... */
237 spin_unlock_bh(&irc_buffer_lock);
241 static struct ip_conntrack_helper irc_helpers[MAX_PORTS];
242 static char irc_names[MAX_PORTS][sizeof("irc-65535")];
244 static void ip_conntrack_irc_fini(void);
246 static int __init ip_conntrack_irc_init(void)
249 struct ip_conntrack_helper *hlpr;
252 if (max_dcc_channels < 1) {
253 printk("ip_conntrack_irc: max_dcc_channels must be a positive integer\n");
257 irc_buffer = kmalloc(65536, GFP_KERNEL);
261 /* If no port given, default to standard irc port */
263 ports[ports_c++] = IRC_PORT;
265 for (i = 0; i < ports_c; i++) {
266 hlpr = &irc_helpers[i];
267 hlpr->tuple.src.u.tcp.port = htons(ports[i]);
268 hlpr->tuple.dst.protonum = IPPROTO_TCP;
269 hlpr->mask.src.u.tcp.port = 0xFFFF;
270 hlpr->mask.dst.protonum = 0xFF;
271 hlpr->max_expected = max_dcc_channels;
272 hlpr->timeout = dcc_timeout;
273 hlpr->me = THIS_MODULE;
276 tmpname = &irc_names[i][0];
277 if (ports[i] == IRC_PORT)
278 sprintf(tmpname, "irc");
280 sprintf(tmpname, "irc-%d", i);
281 hlpr->name = tmpname;
283 DEBUGP("port #%d: %d\n", i, ports[i]);
285 ret = ip_conntrack_helper_register(hlpr);
288 printk("ip_conntrack_irc: ERROR registering port %d\n",
290 ip_conntrack_irc_fini();
297 /* This function is intentionally _NOT_ defined as __exit, because
298 * it is needed by the init function */
299 static void ip_conntrack_irc_fini(void)
302 for (i = 0; i < ports_c; i++) {
303 DEBUGP("unregistering port %d\n",
305 ip_conntrack_helper_unregister(&irc_helpers[i]);
310 module_init(ip_conntrack_irc_init);
311 module_exit(ip_conntrack_irc_fini);