1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
|
/*
* IP_MASQ_IRC irc masquerading module
*
*
* Version: @(#)ip_masq_irc.c 0.01 03/20/96
*
* Author: Juan Jose Ciarlante
*
*
* Fixes:
* - set NO_DADDR flag in ip_masq_new().
*
* FIXME:
* - detect also previous "PRIVMSG" string ?.
*
* 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 <linux/config.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/system.h>
#include <linux/skbuff.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/init.h>
#include <net/protocol.h>
#include <net/tcp.h>
#include <net/ip_masq.h>
#define DEBUG_CONFIG_IP_MASQ_IRC 0
static int
masq_irc_init_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
{
MOD_INC_USE_COUNT;
return 0;
}
static int
masq_irc_done_1 (struct ip_masq_app *mapp, struct ip_masq *ms)
{
MOD_DEC_USE_COUNT;
return 0;
}
int
masq_irc_out (struct ip_masq_app *mapp, struct ip_masq *ms, struct sk_buff **skb_p, __u32 maddr)
{
struct sk_buff *skb;
struct iphdr *iph;
struct tcphdr *th;
char *data, *data_limit;
__u32 s_addr;
__u16 s_port;
struct ip_masq *n_ms;
char buf[20]; /* "m_addr m_port" (dec base)*/
unsigned buf_len;
int diff;
int xtra_args = 0; /* extra int args wanted after addr */
char *dcc_p, *addr_beg_p, *addr_end_p;
skb = *skb_p;
iph = skb->nh.iph;
th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
data = (char *)&th[1];
/*
* Hunt irc DCC string, the _shortest_:
*
* strlen("DCC CHAT chat AAAAAAAA P\x01\n")=26
* strlen("DCC SEND F AAAAAAAA P S\x01\n")=25
* AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits)
* P: bound port (min 1 d )
* F: filename (min 1 d )
* S: size (min 1 d )
* 0x01, \n: terminators
*/
data_limit = skb->h.raw + skb->len;
while (data < (data_limit - 25) )
{
if (memcmp(data,"DCC ",4)) {
data ++;
continue;
}
dcc_p = data;
data += 4; /* point to DCC cmd */
if (memcmp(data, "CHAT ", 5) == 0 ||
memcmp(data, "SEND ", 5) == 0)
{
/*
* extra arg (file_size) req. for "SEND"
*/
if (*data == 'S') xtra_args++;
data += 5;
}
else
continue;
/*
* skip next string.
*/
while( *data++ != ' ')
/*
* must still parse, at least, "AAAAAAAA P\x01\n",
* 12 bytes left.
*/
if (data > (data_limit-12)) return 0;
addr_beg_p = data;
/*
* client bound address in dec base
*/
s_addr = simple_strtoul(data,&data,10);
if (*data++ !=' ')
continue;
/*
* client bound port in dec base
*/
s_port = simple_strtoul(data,&data,10);
addr_end_p = data;
/*
* should check args consistency?
*/
while(xtra_args) {
if (*data != ' ')
break;
data++;
simple_strtoul(data,&data,10);
xtra_args--;
}
if (xtra_args != 0) continue;
/*
* terminators.
*/
if (data[0] != 0x01)
continue;
if (data[1]!='\r' && data[1]!='\n')
continue;
/*
* Now create an masquerade entry for it
* must set NO_DPORT and NO_DADDR because
* connection is requested by another client.
*/
n_ms = ip_masq_new(maddr, IPPROTO_TCP,
htonl(s_addr),htons(s_port),
0, 0,
IP_MASQ_F_NO_DPORT|IP_MASQ_F_NO_DADDR
);
if (n_ms==NULL)
return 0;
ip_masq_set_expire(n_ms, ip_masq_expire->tcp_fin_timeout);
/*
* Replace the old "address port" with the new one
*/
buf_len = sprintf(buf,"%lu %u",
ntohl(n_ms->maddr),ntohs(n_ms->mport));
/*
* Calculate required delta-offset to keep TCP happy
*/
diff = buf_len - (addr_end_p-addr_beg_p);
#if DEBUG_CONFIG_IP_MASQ_IRC
*addr_beg_p = '\0';
printk("masq_irc_out(): '%s' %X:%X detected (diff=%d)\n", dcc_p, s_addr,s_port, diff);
#endif
/*
* No shift.
*/
if (diff==0)
{
/*
* simple case, just copy.
*/
memcpy(addr_beg_p,buf,buf_len);
return 0;
}
*skb_p = ip_masq_skb_replace(skb, GFP_ATOMIC,
addr_beg_p, addr_end_p-addr_beg_p,
buf, buf_len);
return diff;
}
return 0;
}
/*
* Main irc object
* You need 1 object per port in case you need
* to offer also other used irc ports (6665,6666,etc),
* they will share methods but they need own space for
* data.
*/
struct ip_masq_app ip_masq_irc = {
NULL, /* next */
"irc", /* name */
0, /* type */
0, /* n_attach */
masq_irc_init_1, /* init_1 */
masq_irc_done_1, /* done_1 */
masq_irc_out, /* pkt_out */
NULL /* pkt_in */
};
/*
* ip_masq_irc initialization
*/
__initfunc(int ip_masq_irc_init(void))
{
return register_ip_masq_app(&ip_masq_irc, IPPROTO_TCP, 6667);
}
/*
* ip_masq_irc fin.
*/
int ip_masq_irc_done(void)
{
return unregister_ip_masq_app(&ip_masq_irc);
}
#ifdef MODULE
EXPORT_NO_SYMBOLS;
int init_module(void)
{
if (ip_masq_irc_init() != 0)
return -EIO;
return 0;
}
void cleanup_module(void)
{
if (ip_masq_irc_done() != 0)
printk(KERN_INFO "ip_masq_irc: can't remove module");
}
#endif /* MODULE */
|
