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 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; either version
8 * 2 of the License, or (at your option) any later version.
11 #include <linux/module.h>
12 #include <linux/moduleparam.h>
13 #include <linux/skbuff.h>
16 #include <linux/tcp.h>
17 #include <linux/netfilter.h>
19 #include <net/netfilter/nf_conntrack.h>
20 #include <net/netfilter/nf_conntrack_expect.h>
21 #include <net/netfilter/nf_conntrack_helper.h>
22 #include <linux/netfilter/nf_conntrack_irc.h>
25 static unsigned short ports[MAX_PORTS];
26 static unsigned int ports_c;
27 static unsigned int max_dcc_channels = 8;
28 static unsigned int dcc_timeout __read_mostly = 300;
29 /* This is slow, but it's simple. --RR */
30 static char *irc_buffer;
31 static DEFINE_SPINLOCK(irc_buffer_lock);
33 unsigned int (*nf_nat_irc_hook)(struct sk_buff *skb,
34 enum ip_conntrack_info ctinfo,
35 unsigned int matchoff,
36 unsigned int matchlen,
37 struct nf_conntrack_expect *exp) __read_mostly;
38 EXPORT_SYMBOL_GPL(nf_nat_irc_hook);
40 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
41 MODULE_DESCRIPTION("IRC (DCC) connection tracking helper");
42 MODULE_LICENSE("GPL");
43 MODULE_ALIAS("ip_conntrack_irc");
45 module_param_array(ports, ushort, &ports_c, 0400);
46 MODULE_PARM_DESC(ports, "port numbers of IRC servers");
47 module_param(max_dcc_channels, uint, 0400);
48 MODULE_PARM_DESC(max_dcc_channels, "max number of expected DCC channels per "
50 module_param(dcc_timeout, uint, 0400);
51 MODULE_PARM_DESC(dcc_timeout, "timeout on for unestablished DCC channels");
53 static const char *dccprotos[] = {
54 "SEND ", "CHAT ", "MOVE ", "TSEND ", "SCHAT "
59 /* tries to get the ip_addr and port out of a dcc command
60 * return value: -1 on failure, 0 on success
61 * data pointer to first byte of DCC command data
62 * data_end pointer to last byte of dcc command data
63 * ip returns parsed ip of dcc command
64 * port returns parsed port of dcc command
65 * ad_beg_p returns pointer to first byte of addr data
66 * ad_end_p returns pointer to last byte of addr data
68 static int parse_dcc(char *data, char *data_end, u_int32_t *ip,
69 u_int16_t *port, char **ad_beg_p, char **ad_end_p)
71 /* at least 12: "AAAAAAAA P\1\n" */
72 while (*data++ != ' ')
73 if (data > data_end - 12)
77 *ip = simple_strtoul(data, &data, 10);
79 /* skip blanks between ip and port */
80 while (*data == ' ') {
86 *port = simple_strtoul(data, &data, 10);
92 static int help(struct sk_buff *skb, unsigned int protoff,
93 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
97 struct tcphdr _tcph, *th;
98 char *data, *data_limit, *ib_ptr;
99 int dir = CTINFO2DIR(ctinfo);
100 struct nf_conntrack_expect *exp;
101 struct nf_conntrack_tuple *tuple;
105 int i, ret = NF_ACCEPT;
106 char *addr_beg_p, *addr_end_p;
107 typeof(nf_nat_irc_hook) nf_nat_irc;
109 /* If packet is coming from IRC server */
110 if (dir == IP_CT_DIR_REPLY)
113 /* Until there's been traffic both ways, don't look in packets. */
114 if (ctinfo != IP_CT_ESTABLISHED &&
115 ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY)
118 /* Not a full tcp header? */
119 th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
124 dataoff = protoff + th->doff*4;
125 if (dataoff >= skb->len)
128 spin_lock_bh(&irc_buffer_lock);
129 ib_ptr = skb_header_pointer(skb, dataoff, skb->len - dataoff,
131 BUG_ON(ib_ptr == NULL);
134 data_limit = ib_ptr + skb->len - dataoff;
136 /* strlen("\1DCC SENT t AAAAAAAA P\1\n")=24
137 * 5+MINMATCHLEN+strlen("t AAAAAAAA P\1\n")=14 */
138 while (data < data_limit - (19 + MINMATCHLEN)) {
139 if (memcmp(data, "\1DCC ", 5)) {
144 /* we have at least (19+MINMATCHLEN)-5 bytes valid data left */
147 pr_debug("DCC found in master %u.%u.%u.%u:%u %u.%u.%u.%u:%u\n",
148 NIPQUAD(iph->saddr), ntohs(th->source),
149 NIPQUAD(iph->daddr), ntohs(th->dest));
151 for (i = 0; i < ARRAY_SIZE(dccprotos); i++) {
152 if (memcmp(data, dccprotos[i], strlen(dccprotos[i]))) {
156 data += strlen(dccprotos[i]);
157 pr_debug("DCC %s detected\n", dccprotos[i]);
160 * (19+MINMATCHLEN)-5-dccprotos[i].matchlen bytes valid
161 * data left (== 14/13 bytes) */
162 if (parse_dcc((char *)data, data_limit, &dcc_ip,
163 &dcc_port, &addr_beg_p, &addr_end_p)) {
164 pr_debug("unable to parse dcc command\n");
167 pr_debug("DCC bound ip/port: %u.%u.%u.%u:%u\n",
168 HIPQUAD(dcc_ip), dcc_port);
170 /* dcc_ip can be the internal OR external (NAT'ed) IP */
171 tuple = &ct->tuplehash[dir].tuple;
172 if (tuple->src.u3.ip != htonl(dcc_ip) &&
173 tuple->dst.u3.ip != htonl(dcc_ip)) {
176 "Forged DCC command from "
177 "%u.%u.%u.%u: %u.%u.%u.%u:%u\n",
178 NIPQUAD(tuple->src.u3.ip),
179 HIPQUAD(dcc_ip), dcc_port);
183 exp = nf_ct_expect_alloc(ct);
188 tuple = &ct->tuplehash[!dir].tuple;
189 port = htons(dcc_port);
190 nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT,
192 NULL, &tuple->dst.u3,
193 IPPROTO_TCP, NULL, &port);
195 nf_nat_irc = rcu_dereference(nf_nat_irc_hook);
196 if (nf_nat_irc && ct->status & IPS_NAT_MASK)
197 ret = nf_nat_irc(skb, ctinfo,
199 addr_end_p - addr_beg_p,
201 else if (nf_ct_expect_related(exp) != 0)
203 nf_ct_expect_put(exp);
208 spin_unlock_bh(&irc_buffer_lock);
212 static struct nf_conntrack_helper irc[MAX_PORTS] __read_mostly;
213 static char irc_names[MAX_PORTS][sizeof("irc-65535")] __read_mostly;
214 static struct nf_conntrack_expect_policy irc_exp_policy;
216 static void nf_conntrack_irc_fini(void);
218 static int __init nf_conntrack_irc_init(void)
223 if (max_dcc_channels < 1) {
224 printk("nf_ct_irc: max_dcc_channels must not be zero\n");
228 irc_exp_policy.max_expected = max_dcc_channels;
229 irc_exp_policy.timeout = dcc_timeout;
231 irc_buffer = kmalloc(65536, GFP_KERNEL);
235 /* If no port given, default to standard irc port */
237 ports[ports_c++] = IRC_PORT;
239 for (i = 0; i < ports_c; i++) {
240 irc[i].tuple.src.l3num = AF_INET;
241 irc[i].tuple.src.u.tcp.port = htons(ports[i]);
242 irc[i].tuple.dst.protonum = IPPROTO_TCP;
243 irc[i].expect_policy = &irc_exp_policy;
244 irc[i].me = THIS_MODULE;
247 tmpname = &irc_names[i][0];
248 if (ports[i] == IRC_PORT)
249 sprintf(tmpname, "irc");
251 sprintf(tmpname, "irc-%u", i);
252 irc[i].name = tmpname;
254 ret = nf_conntrack_helper_register(&irc[i]);
256 printk("nf_ct_irc: failed to register helper "
257 "for pf: %u port: %u\n",
258 irc[i].tuple.src.l3num, ports[i]);
259 nf_conntrack_irc_fini();
266 /* This function is intentionally _NOT_ defined as __exit, because
267 * it is needed by the init function */
268 static void nf_conntrack_irc_fini(void)
272 for (i = 0; i < ports_c; i++)
273 nf_conntrack_helper_unregister(&irc[i]);
277 module_init(nf_conntrack_irc_init);
278 module_exit(nf_conntrack_irc_fini);