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
|
/*
* stunnel Universal SSL tunnel
* Copyright (c) 1998-2001 Michal Trojnara <Michal.Trojnara@mirt.net>
* All Rights Reserved
*
* 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*
* In addition, as a special exception, Michal Trojnara gives
* permission to link the code of this program with the OpenSSL
* library (or with modified versions of OpenSSL that use the same
* license as OpenSSL), and distribute linked combinations including
* the two. You must obey the GNU General Public License in all
* respects for all of the code used other than OpenSSL. If you modify
* this file, you may extend this exception to your version of the
* file, but you are not obligated to do so. If you do not wish to
* do so, delete this exception statement from your version.
*/
#include "common.h"
#include "prototypes.h"
#include "client.h"
/* protocol-specific function prototypes */
static int smb_client(CLI *);
static int smb_server(CLI *);
static int smtp_client(CLI *);
static int smtp_server(CLI *);
static int pop3_client(CLI *);
static int pop3_server(CLI *);
static int nntp_client(CLI *);
static int nntp_server(CLI *);
static int telnet_client(CLI *);
static int telnet_server(CLI *);
static int RFC2487(int);
int negotiate(char *protocol, int client, CLI *c) {
if(!protocol)
return 0; /* No protocol negotiations */
if(!c)
return 0; /* No client present */
log(LOG_DEBUG, "Negotiations for %s(%s side) started", protocol,
client ? "client" : "server");
if(!strcmp(protocol, "smb")) {
if(client)
return smb_client(c);
else
return smb_server(c);
}
if(!strcmp(protocol, "smtp")) {
if(client)
return smtp_client(c);
else
return smtp_server(c);
}
if(!strcmp(protocol, "pop3")) {
if(client)
return pop3_client(c);
else
return pop3_server(c);
}
if(!strcmp(protocol, "nntp")) {
if(client)
return nntp_client(c);
else
return nntp_server(c);
}
if(!strcmp(protocol, "telnet")) {
if(client)
return telnet_client(c);
else
return telnet_server(c);
}
log(LOG_ERR, "Protocol %s not supported in %s mode",
protocol, client ? "client" : "server");
return -1;
}
static int smb_client(CLI *c) {
log(LOG_ERR, "Protocol not supported");
return -1;
}
static int smb_server(CLI *c) {
log(LOG_ERR, "Protocol not supported");
return -1;
}
static int smtp_client(CLI *c) {
char line[STRLEN];
do { /* Copy multiline greeting */
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
if(fdprintf(c->local_wfd, "%s", line)<0)
return -1;
} while(strncmp(line,"220-",4)==0);
if(fdprintf(c->remote_fd, "EHLO localhost")<0) /* Send an EHLO command */
return -1;
do { /* Skip multiline reply */
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
} while(strncmp(line,"250-",4)==0);
if(strncmp(line,"250 ",4)!=0) { /* Error */
log(LOG_ERR, "Remote server is not RFC 1425 compliant");
return -1;
}
if(fdprintf(c->remote_fd, "STARTTLS")<0) /* Send STARTTLS command */
return -1;
do { /* Skip multiline reply */
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
} while(strncmp(line,"220-",4)==0);
if(strncmp(line,"220 ",4)!=0) { /* Error */
log(LOG_ERR, "Remote server is not RFC 2487 compliant");
return -1;
}
return 0;
}
static int smtp_server(CLI *c) {
char line[STRLEN];
if(RFC2487(c->local_rfd)==0)
return 0; /* Return if RFC 2487 is not used */
if(fdscanf(c->remote_fd, "220%[^\n]", line)!=1) {
log(LOG_ERR, "Unknown server welcome");
return -1;
}
if(fdprintf(c->local_wfd, "220%s + stunnel", line)<0)
return -1;
if(fdscanf(c->local_rfd, "EHLO %[^\n]", line)!=1) {
log(LOG_ERR, "Unknown client EHLO");
return -1;
}
if(fdprintf(c->local_wfd, "250-%s Welcome", line)<0)
return -1;
if(fdprintf(c->local_wfd, "250 STARTTLS")<0)
return -1;
if(fdscanf(c->local_rfd, "STARTTLS", line)<0) {
log(LOG_ERR, "STARTTLS expected");
return -1;
}
if(fdprintf(c->local_wfd, "220 Go ahead", line)<0)
return -1;
return 0;
}
static int pop3_client(CLI *c) {
char line[STRLEN];
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
if(strncmp(line,"+OK ",4)) {
log(LOG_ERR, "Unknown server welcome");
return -1;
}
if(fdprintf(c->local_wfd, "%s", line)<0)
return -1;
if(fdprintf(c->remote_fd, "STLS")<0)
return -1;
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
if(strncmp(line,"+OK ",4)) {
log(LOG_ERR, "Server does not support TLS");
return -1;
}
return 0;
}
static int pop3_server(CLI *c) {
char line[STRLEN];
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
if(fdprintf(c->local_wfd, "%s + stunnel", line)<0)
return -1;
if(fdscanf(c->local_rfd, "%[^\n]", line)<0)
return -1;
if(!strncmp(line, "CAPA", 4)) { /* Client wants RFC 2449 extensions */
if(fdprintf(c->local_wfd, "-ERR Stunnel does not support capabilities")<0)
return -1;
if(fdscanf(c->local_rfd, "%[^\n]", line)<0)
return -1;
}
if(strncmp(line, "STLS", 4)) {
log(LOG_ERR, "Client does not want TLS");
return -1;
}
if(fdprintf(c->local_wfd, "+OK Stunnel starts TLS negotiation")<0)
return -1;
return 0;
}
static int nntp_client(CLI *c) {
char line[STRLEN];
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
if(strncmp(line,"200 ",4) && strncmp(line,"201 ",4)) {
log(LOG_ERR, "Unknown server welcome");
return -1;
}
if(fdprintf(c->local_wfd, "%s", line)<0)
return -1;
if(fdprintf(c->remote_fd, "STARTTLS")<0)
return -1;
if(fdscanf(c->remote_fd, "%[^\n]", line)<0)
return -1;
if(strncmp(line,"382 ",4)) {
log(LOG_ERR, "Server does not support TLS");
return -1;
}
return 0;
}
static int nntp_server(CLI *c) {
log(LOG_ERR, "Protocol not supported in server mode");
return -1;
}
static int telnet_client(CLI *c) {
log(LOG_ERR, "Protocol not supported");
return -1;
}
static int telnet_server(CLI *c) {
log(LOG_ERR, "Protocol not supported");
return -1;
}
static int RFC2487(int fd) {
fd_set fdsRead;
struct timeval timeout;
FD_ZERO(&fdsRead);
FD_SET(fd, &fdsRead);
timeout.tv_sec=timeout.tv_usec=0; /* don't wait */
switch(select(fd+1, &fdsRead, NULL, NULL, &timeout)) {
case 0: /* fd not ready to read */
log(LOG_DEBUG, "RFC 2487 detected");
return 1;
case 1: /* fd ready to read */
log(LOG_DEBUG, "RFC 2487 not detected");
return 0;
}
sockerror("RFC2487 (select)");
return -1;
}
/* End of protocol.c */
|
