aboutsummaryrefslogtreecommitdiff
path: root/socks.c
blob: 82872743221c9d44a7be562cdf4d80cb1245ffca (plain) (blame)
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
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single TCP/UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  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 (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/*
 * 2004-01-30: Added Socks5 proxy support, see RFC 1928
 *   (Christof Meerwald, http://cmeerw.org)
 *
 * 2010-10-10: Added Socks5 plain text authentication support (RFC 1929)
 *   (Pierre Bourdon <delroth@gmail.com>)
 */

#include "syshead.h"

#ifdef ENABLE_SOCKS

#include "common.h"
#include "misc.h"
#include "win32.h"
#include "socket.h"
#include "fdmisc.h"
#include "misc.h"
#include "proxy.h"

#include "memdbg.h"

#define UP_TYPE_SOCKS		"SOCKS Proxy"

void
socks_adjust_frame_parameters (struct frame *frame, int proto)
{
  if (proto == PROTO_UDPv4)
    frame_add_to_extra_link (frame, 10);
}

struct socks_proxy_info *
socks_proxy_new (const char *server,
		 int port,
		 const char *authfile,
		 bool retry,
		 struct auto_proxy_info *auto_proxy_info)
{
  struct socks_proxy_info *p;

  if (auto_proxy_info)
    {
      if (!server)
	{
	  if (!auto_proxy_info->socks.server)
	    return NULL;

	  server = auto_proxy_info->socks.server;
	  port = auto_proxy_info->socks.port;
	}
    }

  ALLOC_OBJ_CLEAR (p, struct socks_proxy_info);

  ASSERT (server);
  ASSERT (legal_ipv4_port (port));

  strncpynt (p->server, server, sizeof (p->server));
  p->port = port;

  if (authfile)
    strncpynt (p->authfile, authfile, sizeof (p->authfile));
  else
    p->authfile[0] = 0;

  p->retry = retry;
  p->defined = true;

  return p;
}

void
socks_proxy_close (struct socks_proxy_info *sp)
{
  free (sp);
}

static bool
socks_username_password_auth (struct socks_proxy_info *p,
                              socket_descriptor_t sd,
                              volatile int *signal_received)
{
  char to_send[516];
  char buf[2];
  int len = 0;
  const int timeout_sec = 5;
  struct user_pass creds;
  ssize_t size;

  creds.defined = 0;
  get_user_pass (&creds, p->authfile, UP_TYPE_SOCKS, GET_USER_PASS_MANAGEMENT);

  if( !creds.username || (strlen(creds.username) > 255)
      || !creds.password || (strlen(creds.password) > 255) ) {
          msg (M_NONFATAL,
               "SOCKS username and/or password exceeds 255 characters.  "
               "Authentication not possible.");
          return false;
  }
  openvpn_snprintf (to_send, sizeof (to_send), "\x01%c%s%c%s", (int) strlen(creds.username),
            creds.username, (int) strlen(creds.password), creds.password);
  size = send (sd, to_send, strlen(to_send), MSG_NOSIGNAL);

  if (size != strlen (to_send))
    {
      msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_username_password_auth: TCP port write failed on send()");
      return false;
    }

  while (len < 2)
    {
      int status;
      ssize_t size;
      fd_set reads;
      struct timeval tv;
      char c;

      FD_ZERO (&reads);
      FD_SET (sd, &reads);
      tv.tv_sec = timeout_sec;
      tv.tv_usec = 0;

      status = select (sd + 1, &reads, NULL, NULL, &tv);

      get_signal (signal_received);
      if (*signal_received)
	return false;

      /* timeout? */
      if (status == 0)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_username_password_auth: TCP port read timeout expired");
	  return false;
	}

      /* error */
      if (status < 0)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_username_password_auth: TCP port read failed on select()");
	  return false;
	}

      /* read single char */
      size = recv(sd, &c, 1, MSG_NOSIGNAL);

      /* error? */
      if (size != 1)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_username_password_auth: TCP port read failed on recv()");
	  return false;
	}

      /* store char in buffer */
      buf[len++] = c;
    }

  /* VER = 5, SUCCESS = 0 --> auth success */
  if (buf[0] != 5 && buf[1] != 0)
  {
    msg (D_LINK_ERRORS, "socks_username_password_auth: server refused the authentication");
    return false;
  }

  return true;
}

static bool
socks_handshake (struct socks_proxy_info *p,
                 socket_descriptor_t sd,
                 volatile int *signal_received)
{
  char buf[2];
  int len = 0;
  const int timeout_sec = 5;

  /* VER = 5, NMETHODS = 2, METHODS = [0 (no auth), 2 (plain login)] */
  const ssize_t size = send (sd, "\x05\x02\x00\x02", 4, MSG_NOSIGNAL);
  if (size != 4)
    {
      msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port write failed on send()");
      return false;
    }

  while (len < 2)
    {
      int status;
      ssize_t size;
      fd_set reads;
      struct timeval tv;
      char c;

      FD_ZERO (&reads);
      FD_SET (sd, &reads);
      tv.tv_sec = timeout_sec;
      tv.tv_usec = 0;

      status = select (sd + 1, &reads, NULL, NULL, &tv);

      get_signal (signal_received);
      if (*signal_received)
	return false;

      /* timeout? */
      if (status == 0)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port read timeout expired");
	  return false;
	}

      /* error */
      if (status < 0)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port read failed on select()");
	  return false;
	}

      /* read single char */
      size = recv(sd, &c, 1, MSG_NOSIGNAL);

      /* error? */
      if (size != 1)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "socks_handshake: TCP port read failed on recv()");
	  return false;
	}

      /* store char in buffer */
      buf[len++] = c;
    }

  /* VER == 5 */
  if (buf[0] != '\x05')
    {
      msg (D_LINK_ERRORS, "socks_handshake: Socks proxy returned bad status");
      return false;
    }

  /* select the appropriate authentication method */
  switch (buf[1])
    {
    case 0: /* no authentication */
      break;

    case 2: /* login/password */
      if (!p->authfile[0])
      {
	msg(D_LINK_ERRORS, "socks_handshake: server asked for username/login auth but we were "
	                   "not provided any credentials");
	return false;
      }

      if (!socks_username_password_auth(p, sd, signal_received))
	return false;

      break;

    default: /* unknown auth method */
      msg(D_LINK_ERRORS, "socks_handshake: unknown SOCKS auth method");
      return false;
    }

  return true;
}

static bool
recv_socks_reply (socket_descriptor_t sd,
		  struct openvpn_sockaddr *addr,
		  volatile int *signal_received)
{
  char atyp = '\0';
  int alen = 0;
  int len = 0;
  char buf[22];
  const int timeout_sec = 5;

  if (addr != NULL)
    {
      addr->sa.sin_family = AF_INET;
      addr->sa.sin_addr.s_addr = htonl (INADDR_ANY);
      addr->sa.sin_port = htons (0);
    }

  while (len < 4 + alen + 2)
    {
      int status;
      ssize_t size;
      fd_set reads;
      struct timeval tv;
      char c;

      FD_ZERO (&reads);
      FD_SET (sd, &reads);
      tv.tv_sec = timeout_sec;
      tv.tv_usec = 0;

      status = select (sd + 1, &reads, NULL, NULL, &tv);

      get_signal (signal_received);
      if (*signal_received)
	return false;

      /* timeout? */
      if (status == 0)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_socks_reply: TCP port read timeout expired");
	  return false;
	}

      /* error */
      if (status < 0)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_socks_reply: TCP port read failed on select()");
	  return false;
	}

      /* read single char */
      size = recv(sd, &c, 1, MSG_NOSIGNAL);

      /* error? */
      if (size != 1)
	{
	  msg (D_LINK_ERRORS | M_ERRNO_SOCK, "recv_socks_reply: TCP port read failed on recv()");
	  return false;
	}

      if (len == 3)
	atyp = c;

      if (len == 4)
	{
	  switch (atyp)
	    {
	    case '\x01':	/* IP V4 */
	      alen = 4;
	      break;

	    case '\x03':	/* DOMAINNAME */
	      alen = (unsigned char) c;
	      break;

	    case '\x04':	/* IP V6 */
	      alen = 16;
	      break;

	    default:
	      msg (D_LINK_ERRORS, "recv_socks_reply: Socks proxy returned bad address type");
	      return false;
	    }
	}

      /* store char in buffer */
      if (len < (int)sizeof(buf))
	buf[len] = c;
      ++len;
    }

  /* VER == 5 && REP == 0 (succeeded) */
  if (buf[0] != '\x05' || buf[1] != '\x00')
    {
      msg (D_LINK_ERRORS, "recv_socks_reply: Socks proxy returned bad reply");
      return false;
    }

  /* ATYP == 1 (IP V4 address) */
  if (atyp == '\x01' && addr != NULL)
    {
      memcpy (&addr->sa.sin_addr, buf + 4, sizeof (addr->sa.sin_addr));
      memcpy (&addr->sa.sin_port, buf + 8, sizeof (addr->sa.sin_port));
    }


  return true;
}

void
establish_socks_proxy_passthru (struct socks_proxy_info *p,
			        socket_descriptor_t sd, /* already open to proxy */
			        const char *host,       /* openvpn server remote */
			        const int port,         /* openvpn server port */
			        volatile int *signal_received)
{
  char buf[128];
  size_t len;

  if (!socks_handshake (p, sd, signal_received))
    goto error;

  /* format Socks CONNECT message */
  buf[0] = '\x05';		/* VER = 5 */
  buf[1] = '\x01';		/* CMD = 1 (CONNECT) */
  buf[2] = '\x00';		/* RSV */
  buf[3] = '\x03';		/* ATYP = 3 (DOMAINNAME) */

  len = strlen(host);
  len = (5 + len + 2 > sizeof(buf)) ? (sizeof(buf) - 5 - 2) : len;

  buf[4] = (char) len;
  memcpy(buf + 5, host, len);

  buf[5 + len] = (char) (port >> 8);
  buf[5 + len + 1] = (char) (port & 0xff);

  {
    const ssize_t size = send (sd, buf, 5 + len + 2, MSG_NOSIGNAL);
    if ((int)size != 5 + (int)len + 2)
      {
	msg (D_LINK_ERRORS | M_ERRNO_SOCK, "establish_socks_proxy_passthru: TCP port write failed on send()");
	goto error;
      }
  }

  /* receive reply from Socks proxy and discard */
  if (!recv_socks_reply (sd, NULL, signal_received))
    goto error;

  return;

 error:
  /* on error, should we exit or restart? */
  if (!*signal_received)
    *signal_received = (p->retry ? SIGUSR1 : SIGTERM); /* SOFT-SIGUSR1 -- socks error */
  return;
}

void
establish_socks_proxy_udpassoc (struct socks_proxy_info *p,
			        socket_descriptor_t ctrl_sd, /* already open to proxy */
				socket_descriptor_t udp_sd,
				struct openvpn_sockaddr *relay_addr,
			        volatile int *signal_received)
{
  if (!socks_handshake (p, ctrl_sd, signal_received))
    goto error;

  {
    /* send Socks UDP ASSOCIATE message */
    /* VER = 5, CMD = 3 (UDP ASSOCIATE), RSV = 0, ATYP = 1 (IP V4),
       BND.ADDR = 0, BND.PORT = 0 */
    const ssize_t size = send (ctrl_sd,
			       "\x05\x03\x00\x01\x00\x00\x00\x00\x00\x00",
			       10, MSG_NOSIGNAL);
    if (size != 10)
      {
	msg (D_LINK_ERRORS | M_ERRNO_SOCK, "establish_socks_proxy_passthru: TCP port write failed on send()");
	goto error;
      }
  }

  /* receive reply from Socks proxy */
  CLEAR (*relay_addr);
  if (!recv_socks_reply (ctrl_sd, relay_addr, signal_received))
    goto error;

  return;

 error:
  /* on error, should we exit or restart? */
  if (!*signal_received)
    *signal_received = (p->retry ? SIGUSR1 : SIGTERM); /* SOFT-SIGUSR1 -- socks error */
  return;
}

/*
 * Remove the 10 byte socks5 header from an incoming
 * UDP packet, setting *from to the source address.
 *
 * Run after UDP read.
 */
void
socks_process_incoming_udp (struct buffer *buf,
			    struct link_socket_actual *from)
{
  int atyp;

  if (BLEN (buf) < 10)
    goto error;

  buf_read_u16 (buf);
  if (buf_read_u8 (buf) != 0)
    goto error;

  atyp = buf_read_u8 (buf);
  if (atyp != 1)		/* ATYP == 1 (IP V4) */
    goto error;

  buf_read (buf, &from->dest.sa.sin_addr, sizeof (from->dest.sa.sin_addr));
  buf_read (buf, &from->dest.sa.sin_port, sizeof (from->dest.sa.sin_port));

  return;

 error:
  buf->len = 0;
}

/*
 * Add a 10 byte socks header prior to UDP write.
 * *to is the destination address.
 *
 * Run before UDP write.
 * Returns the size of the header.
 */
int
socks_process_outgoing_udp (struct buffer *buf,
			    const struct link_socket_actual *to)
{
  /* 
   * Get a 10 byte subset buffer prepended to buf --
   * we expect these bytes will be here because
   * we allocated frame space in socks_adjust_frame_parameters.
   */
  struct buffer head = buf_sub (buf, 10, true);

  /* crash if not enough headroom in buf */
  ASSERT (buf_defined (&head));

  buf_write_u16 (&head, 0);	/* RSV = 0 */
  buf_write_u8 (&head, 0);	/* FRAG = 0 */
  buf_write_u8 (&head, '\x01'); /* ATYP = 1 (IP V4) */
  buf_write (&head, &to->dest.sa.sin_addr, sizeof (to->dest.sa.sin_addr));
  buf_write (&head, &to->dest.sa.sin_port, sizeof (to->dest.sa.sin_port));

  return 10;
}

#else
static void dummy(void) {}
#endif /* ENABLE_SOCKS */