summaryrefslogtreecommitdiffstats
path: root/ps.c
blob: a97bbe5031caa770cd5046a419ecef88a682e0b7 (plain)
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
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
/*
 *  OpenVPN -- An application to securely tunnel IP networks
 *             over a single UDP port, with support for SSL/TLS-based
 *             session authentication and key exchange,
 *             packet encryption, packet authentication, and
 *             packet compression.
 *
 *  Copyright (C) 2002-2005 OpenVPN Solutions LLC <info@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
 */

#ifdef WIN32
#include "config-win32.h"
#else
#include "config.h"
#endif

#include "syshead.h"

#if PORT_SHARE

#include "event.h"
#include "socket.h"
#include "fdmisc.h"
#include "ps.h"

#include "memdbg.h"

struct port_share *port_share = NULL; /* GLOBAL */

/* size of i/o buffers */
#define PROXY_CONNECTION_BUFFER_SIZE 1500

/* Command codes for foreground -> background communication */
#define COMMAND_REDIRECT 10
#define COMMAND_EXIT     11

/* Response codes for background -> foreground communication */
#define RESPONSE_INIT_SUCCEEDED   20
#define RESPONSE_INIT_FAILED      21

/*
 * Return values for proxy_connection_io functions
 */

#define IOSTAT_EAGAIN_ON_READ   0 /* recv returned EAGAIN */
#define IOSTAT_EAGAIN_ON_WRITE  1 /* send returned EAGAIN */
#define IOSTAT_READ_ERROR       2 /* the other end of our read socket (pc) was closed */
#define IOSTAT_WRITE_ERROR      3 /* the other end of our write socket (pc->counterpart) was closed */
#define IOSTAT_GOOD             4 /* nothing to report */

/*
 * A foreign (non-OpenVPN) connection we are proxying,
 * usually HTTPS
 */
struct proxy_connection {
  bool defined;
  struct proxy_connection *next;
  struct proxy_connection *counterpart;
  struct buffer buf;
  bool buffer_initial;
  int rwflags;
  int sd;
};

/* used for passing fds between processes */
union fdmsg {
  struct cmsghdr h;
  char buf[CMSG_SPACE(sizeof(socket_descriptor_t))];
};

#if 0
static const char *
headc (const struct buffer *buf)
{
  static char foo[16];
  strncpy (foo, BSTR(buf), 15);
  foo[15] = 0;
  return foo;
}
#endif

static inline void
close_socket_if_defined (const socket_descriptor_t sd)
{
  if (socket_defined (sd))
    openvpn_close_socket (sd);
}

/*
 * Close most of parent's fds.
 * Keep stdin/stdout/stderr, plus one
 * other fd which is presumed to be
 * our pipe back to parent.
 * Admittedly, a bit of a kludge,
 * but posix doesn't give us a kind
 * of FD_CLOEXEC which will stop
 * fds from crossing a fork().
 */
static void
close_fds_except (int keep)
{
  socket_descriptor_t i;
  closelog ();
  for (i = 3; i <= 100; ++i)
    {
      if (i != keep)
	openvpn_close_socket (i);
    }
}

/*
 * Usually we ignore signals, because our parent will
 * deal with them.
 */
static void
set_signals (void)
{
  signal (SIGTERM, SIG_DFL);

  signal (SIGINT, SIG_IGN);
  signal (SIGHUP, SIG_IGN);
  signal (SIGUSR1, SIG_IGN);
  signal (SIGUSR2, SIG_IGN);
  signal (SIGPIPE, SIG_IGN);
}

/*
 * Socket read/write functions.
 */

static int
recv_control (const socket_descriptor_t fd)
{
  unsigned char c;
  const ssize_t size = read (fd, &c, sizeof (c));
  if (size == sizeof (c))
    return c;
  else
    {
      return -1;
    }
}

static int
send_control (const socket_descriptor_t fd, int code)
{
  unsigned char c = (unsigned char) code;
  const ssize_t size = write (fd, &c, sizeof (c));
  if (size == sizeof (c))
    return (int) size;
  else
    return -1;
}

/*
 * Send a command (char), data (head), and a file descriptor (sd_send) to a local process
 * over unix socket sd.  Unfortunately, there's no portable way to send file descriptors
 * to other processes, so this code, as well as its analog (control_message_from_parent below),
 * is Linux-specific. This function runs in the context of the main process and is used to
 * send commands, data, and file descriptors to the background process.
 */
static void
port_share_sendmsg (const socket_descriptor_t sd,
		    const char command,
		    const struct buffer *head,
		    const socket_descriptor_t sd_send)
{
  if (socket_defined (sd))
    {
      struct msghdr mesg;
      union fdmsg cmsg;
      struct cmsghdr* h;
      struct iovec iov[2];
      socket_descriptor_t sd_null[2] = { SOCKET_UNDEFINED, SOCKET_UNDEFINED };
      char cmd;
      ssize_t status;

      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: sendmsg sd=%d len=%d",
	    (int)sd_send,
	    head ? BLEN(head) : -1);

      CLEAR (mesg);

      cmd = command;

      iov[0].iov_base = &cmd;
      iov[0].iov_len = sizeof (cmd);
      mesg.msg_iovlen = 1;

      if (head)
	{
	  iov[1].iov_base = BPTR (head);
	  iov[1].iov_len = BLEN (head);
	  mesg.msg_iovlen = 2;
	}

      mesg.msg_iov = iov;

      mesg.msg_control = cmsg.buf;
      mesg.msg_controllen = sizeof (union fdmsg);
      mesg.msg_flags = 0;

      h = CMSG_FIRSTHDR(&mesg);
      h->cmsg_level = SOL_SOCKET;
      h->cmsg_type = SCM_RIGHTS;
      h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));

      if (socket_defined (sd_send))
	{
	  *((socket_descriptor_t*)CMSG_DATA(h)) = sd_send;
	}
      else
	{
	  socketpair (PF_UNIX, SOCK_DGRAM, 0, sd_null);
	  *((socket_descriptor_t*)CMSG_DATA(h)) = sd_null[0];
	}

      status = sendmsg (sd, &mesg, MSG_NOSIGNAL);
      if (status == -1)
	msg (M_WARN, "PORT SHARE: sendmsg failed (unable to communicate with background process)");

      close_socket_if_defined (sd_null[0]);
      close_socket_if_defined (sd_null[1]);
    }
}

static int
pc_list_len (struct proxy_connection *pc)
{
  int count = 0;
  while (pc)
    {
      ++count;
      pc = pc->next;
    }
  return count;
}

static void
proxy_entry_close_sd (struct proxy_connection *pc, struct event_set *es)
{
  if (pc->defined && socket_defined (pc->sd))
    {
      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: delete sd=%d", (int)pc->sd);
      if (es)
	event_del (es, pc->sd);
      openvpn_close_socket (pc->sd);
      pc->sd = SOCKET_UNDEFINED;
    }
}

/*
 * Mark a proxy entry and its counterpart for close.
 */
static void
proxy_entry_mark_for_close (struct proxy_connection *pc, struct event_set *es)
{
  if (pc->defined)
    {
      struct proxy_connection *cp = pc->counterpart;
      proxy_entry_close_sd (pc, es);
      free_buf (&pc->buf);
      pc->buffer_initial = false;
      pc->rwflags = 0;
      pc->defined = false;
      if (cp && cp->defined && cp->counterpart == pc)
	proxy_entry_mark_for_close (cp, es);
    }
}

/*
 * Run through the proxy entry list and delete all entries marked
 * for close.
 */
static void
proxy_list_housekeeping (struct proxy_connection **list)
{
  if (list)
    {
      struct proxy_connection *prev = NULL;
      struct proxy_connection *pc = *list;

      while (pc)
	{
	  struct proxy_connection *next = pc->next;
	  if (!pc->defined)
	    {
	      free (pc);
	      if (prev)
		prev->next = next;
	      else
		*list = next;
	    }
	  else
	    prev = pc;
	  pc = next;
	}
    }
}

/*
 * Cleanup function, on proxy process exit.
 */
static void
proxy_list_close (struct proxy_connection **list)
{
  if (list)
    {
      struct proxy_connection *pc = *list;
      while (pc)
	{
	  proxy_entry_mark_for_close (pc, NULL);
	  pc = pc->next;
	}
      proxy_list_housekeeping (list);
    }
}

static void
sock_addr_set (struct openvpn_sockaddr *osaddr,
	       const in_addr_t addr,
	       const int port)
{
  CLEAR (*osaddr);
  osaddr->sa.sin_family = AF_INET;
  osaddr->sa.sin_addr.s_addr = htonl (addr);
  osaddr->sa.sin_port = htons (port);
}

static inline void
proxy_connection_io_requeue (struct proxy_connection *pc, const int rwflags_new, struct event_set *es)
{
  if (socket_defined (pc->sd) && pc->rwflags != rwflags_new)
    {
      /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: requeue[%d] rwflags=%d", (int)pc->sd, rwflags_new);*/
      event_ctl (es, pc->sd, rwflags_new, (void*)pc);
      pc->rwflags = rwflags_new;
    }
}

/*
 * Create a new pair of proxy_connection entries, one for each
 * socket file descriptor involved in the proxy.  We are given
 * the client fd, and we should derive our own server fd by connecting
 * to the server given by server_addr/server_port.  Return true
 * on success and false on failure to connect to server.
 */
static bool
proxy_entry_new (struct proxy_connection **list,
		 struct event_set *es,
		 const in_addr_t server_addr,
		 const int server_port,
		 const socket_descriptor_t sd_client,
		 struct buffer *initial_data)
{
  struct openvpn_sockaddr osaddr;
  socket_descriptor_t sd_server;
  int status;
  struct proxy_connection *pc;
  struct proxy_connection *cp;

  /* connect to port share server */
  sock_addr_set (&osaddr, server_addr, server_port);
  sd_server = create_socket_tcp ();
  status = openvpn_connect (sd_server, &osaddr, 5, NULL);
  if (status)
    {
      msg (M_WARN, "PORT SHARE PROXY: connect to port-share server failed");
      openvpn_close_socket (sd_server);
      return false;
    }
  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: connect to port-share server succeeded");

  set_nonblock (sd_client);
  set_nonblock (sd_server);

  /* allocate 2 new proxy_connection objects */
  ALLOC_OBJ_CLEAR (pc, struct proxy_connection);
  ALLOC_OBJ_CLEAR (cp, struct proxy_connection);

  /* client object */
  pc->defined = true;
  pc->next = cp;
  pc->counterpart = cp;
  pc->buf = *initial_data;
  pc->buffer_initial = true;
  pc->rwflags = EVENT_UNDEF;
  pc->sd = sd_client;

  /* server object */
  cp->defined = true;
  cp->next = *list;
  cp->counterpart = pc;
  cp->buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
  cp->buffer_initial = false;
  cp->rwflags = EVENT_UNDEF;
  cp->sd = sd_server;

  /* add to list */
  *list = pc;
  
  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: NEW CONNECTION [c=%d s=%d]", (int)sd_client, (int)sd_server);

  /* set initial i/o states */
  proxy_connection_io_requeue (pc, EVENT_READ, es);
  proxy_connection_io_requeue (cp, EVENT_READ|EVENT_WRITE, es);
  
  return true;
}

/*
 * This function runs in the context of the background proxy process.
 * Receive a control message from the parent (sent by the port_share_sendmsg
 * function above) and act on it.  Return false if the proxy process should
 * exit, true otherwise.
 */
static bool
control_message_from_parent (const socket_descriptor_t sd_control,
			     struct proxy_connection **list,
			     struct event_set *es,
			     const in_addr_t server_addr,
			     const int server_port)
{
  struct buffer buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
  struct msghdr mesg;
  union fdmsg cmsg;
  struct cmsghdr* h;
  struct iovec iov[2];
  char command = 0;
  ssize_t status;
  int ret = true;

  CLEAR (mesg);

  iov[0].iov_base = &command;
  iov[0].iov_len = sizeof (command);
  iov[1].iov_base = BPTR (&buf);
  iov[1].iov_len = BCAP (&buf);
  mesg.msg_iov = iov;
  mesg.msg_iovlen = 2;

  mesg.msg_control = cmsg.buf;
  mesg.msg_controllen = sizeof (union fdmsg);
  mesg.msg_flags = 0;

  h = CMSG_FIRSTHDR(&mesg);
  h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
  h->cmsg_level = SOL_SOCKET;
  h->cmsg_type = SCM_RIGHTS;
  *((socket_descriptor_t*)CMSG_DATA(h)) = SOCKET_UNDEFINED;

  status = recvmsg (sd_control, &mesg, MSG_NOSIGNAL);
  if (status != -1)
    {
      if (   h == NULL
	  || h->cmsg_len    != CMSG_LEN(sizeof(socket_descriptor_t))
	  || h->cmsg_level  != SOL_SOCKET
	  || h->cmsg_type   != SCM_RIGHTS )
	{
	  ret = false;
	}
      else
	{
	  const socket_descriptor_t received_fd = *((socket_descriptor_t*)CMSG_DATA(h));
	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED sd=%d", (int)received_fd);

	  if (status >= 2 && command == COMMAND_REDIRECT)
	    {
	      buf.len = status - 1;
	      if (proxy_entry_new (list,
				   es,
				   server_addr,
				   server_port,
				   received_fd,
				   &buf))
		{
		  CLEAR (buf); /* we gave the buffer to proxy_entry_new */
		}
	      else
		{
		  openvpn_close_socket (received_fd);
		}
	    }
	  else if (status >= 1 && command == COMMAND_EXIT)
	    {
	      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED COMMAND_EXIT");
	      openvpn_close_socket (received_fd); /* null socket */
	      ret = false;
	    }
	}
    }
  free_buf (&buf);
  return ret;
}

static int
proxy_connection_io_recv (struct proxy_connection *pc)
{
  /* recv data from socket */
  const int status = recv (pc->sd, BPTR(&pc->buf), BCAP(&pc->buf), MSG_NOSIGNAL);
  if (status < 0)
    {
      return (errno == EAGAIN) ? IOSTAT_EAGAIN_ON_READ : IOSTAT_READ_ERROR;
    }
  else
    {
      if (!status)
	return IOSTAT_READ_ERROR;
      pc->buf.len = status;
    }
  return IOSTAT_GOOD;
}

static int
proxy_connection_io_send (struct proxy_connection *pc, int *bytes_sent)
{
  const socket_descriptor_t sd = pc->counterpart->sd;
  const int status = send (sd, BPTR(&pc->buf), BLEN(&pc->buf), MSG_NOSIGNAL);

  if (status < 0)
    {
      const int e = errno;
      return (e == EAGAIN) ? IOSTAT_EAGAIN_ON_WRITE : IOSTAT_WRITE_ERROR;
    }
  else
    {
      *bytes_sent += status;
      if (status != pc->buf.len)
	{
	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: partial write[%d], tried=%d got=%d", (int)sd, pc->buf.len, status);
	  buf_advance (&pc->buf, status);
	  return IOSTAT_EAGAIN_ON_WRITE;
	}
      else
	{
	  /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: wrote[%d] %d", (int)sd, status);*/
	  pc->buf.len = 0;
	  pc->buf.offset = 0;
	}
    }

  /* realloc send buffer after initial send */
  if (pc->buffer_initial)
    {
      free_buf (&pc->buf);
      pc->buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
      pc->buffer_initial = false;
    }
  return IOSTAT_GOOD;
}

/*
 * Forward data from pc to pc->counterpart.
 */

static int
proxy_connection_io_xfer (struct proxy_connection *pc, const int max_transfer)
{
  int transferred = 0;
  while (transferred < max_transfer)
    {
      if (!BLEN (&pc->buf))
	{
	  const int status = proxy_connection_io_recv (pc);
	  if (status != IOSTAT_GOOD)
	    return status;
	}

      if (BLEN (&pc->buf))
	{
	  const int status = proxy_connection_io_send (pc, &transferred);
	  if (status != IOSTAT_GOOD)
	    return status;
	}
    }
  return IOSTAT_EAGAIN_ON_READ;
}

/*
 * Decide how the receipt of an EAGAIN status should affect our next IO queueing.
 */
static bool
proxy_connection_io_status (const int status, int *rwflags_pc, int *rwflags_cp)
{
  switch (status)
    {
    case IOSTAT_EAGAIN_ON_READ:
      *rwflags_pc |= EVENT_READ;
      *rwflags_cp &= ~EVENT_WRITE;
      return true;
    case IOSTAT_EAGAIN_ON_WRITE:
      *rwflags_pc &= ~EVENT_READ;
      *rwflags_cp |= EVENT_WRITE;
      return true;
    case IOSTAT_READ_ERROR:
      return false;
    case IOSTAT_WRITE_ERROR:
      return false;
    default:
      msg (M_FATAL, "PORT SHARE PROXY: unexpected status=%d", status);
    }
  return false; /* NOTREACHED */
}

/*
 * Dispatch function for forwarding data between the two socket fds involved
 * in the proxied connection.
 */
static int
proxy_connection_io_dispatch (struct proxy_connection *pc,
			      const int rwflags,
			      struct event_set *es)
{
  const int max_transfer_per_iteration = 10000;
  struct proxy_connection *cp = pc->counterpart;
  int rwflags_pc = pc->rwflags;
  int rwflags_cp = cp->rwflags;

  if (rwflags & EVENT_READ)
    {
      const int status = proxy_connection_io_xfer (pc, max_transfer_per_iteration);
      if (!proxy_connection_io_status (status, &rwflags_pc, &rwflags_cp))
	goto bad;
    }
  if (rwflags & EVENT_WRITE)
    {
      const int status = proxy_connection_io_xfer (cp, max_transfer_per_iteration);
      if (!proxy_connection_io_status (status, &rwflags_cp, &rwflags_pc))
	goto bad;
    }
  proxy_connection_io_requeue (pc, rwflags_pc, es);
  proxy_connection_io_requeue (cp, rwflags_cp, es);

  return true;

 bad:
  proxy_entry_mark_for_close (pc, es);
  return false;
}

/*
 * This is the main function for the port share proxy background process.
 */
static void
port_share_proxy (const in_addr_t hostaddr, const int port, const socket_descriptor_t sd_control)
{
  if (send_control (sd_control, RESPONSE_INIT_SUCCEEDED) >= 0)
    {
      void *sd_control_marker = (void *)1;
      int maxevents = 256;
      struct event_set *es;
      struct event_set_return esr[64];
      struct proxy_connection *list = NULL;
      time_t last_housekeeping = 0;

      msg (D_PS_PROXY, "PORT SHARE PROXY: proxy starting");

      es = event_set_init (&maxevents, 0);
      event_ctl (es, sd_control, EVENT_READ, sd_control_marker);
      while (true)
	{
	  int n_events;
	  struct timeval tv;
	  time_t current;

	  tv.tv_sec = 10;
	  tv.tv_usec = 0;
	  n_events = event_wait (es, &tv, esr, SIZE(esr));
	  /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait returned %d", n_events);*/
	  current = time(NULL);
	  if (n_events > 0)
	    {
	      int i;
	      for (i = 0; i < n_events; ++i)
		{
		  const struct event_set_return *e = &esr[i];
		  if (e->arg == sd_control_marker)
		    {
		      if (!control_message_from_parent (sd_control, &list, es, hostaddr, port))
			goto done;
		    }
		  else
		    {
		      struct proxy_connection *pc = (struct proxy_connection *)e->arg;
		      if (pc->defined)
			proxy_connection_io_dispatch (pc, e->rwflags, es);
		    }
		}
	    }
	  else if (n_events < 0)
	    {
	      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait failed");
	    }
	  if (current > last_housekeeping)
	    {
	      proxy_list_housekeeping (&list);
	      last_housekeeping = current;
	    }
	}

    done:
      proxy_list_close (&list);
      event_free (es);
    }
  msg (D_PS_PROXY, "PORT SHARE PROXY: proxy exiting");
}

/*
 * Called from the main OpenVPN process to enable the port
 * share proxy.
 */
struct port_share *
port_share_open (const char *host, const int port)
{
  pid_t pid;
  socket_descriptor_t fd[2];
  in_addr_t hostaddr;
  struct port_share *ps;

  ALLOC_OBJ_CLEAR (ps, struct port_share);

  /*
   * Get host's IP address
   */
  hostaddr = getaddr (GETADDR_RESOLVE|GETADDR_HOST_ORDER|GETADDR_FATAL, host, 0, NULL, NULL);

  /*
   * Make a socket for foreground and background processes
   * to communicate.
   */
  if (socketpair (PF_UNIX, SOCK_DGRAM, 0, fd) == -1)
    {
      msg (M_WARN, "PORT SHARE: socketpair call failed");
      goto error;
    }

  /*
   * Fork off background proxy process.
   */
  pid = fork ();

  if (pid)
    {
      int status;

      /*
       * Foreground Process
       */

      ps->background_pid = pid;

      /* close our copy of child's socket */
      openvpn_close_socket (fd[1]);

      /* don't let future subprocesses inherit child socket */
      set_cloexec (fd[0]);

      /* wait for background child process to initialize */
      status = recv_control (fd[0]);
      if (status == RESPONSE_INIT_SUCCEEDED)
	{
	  ps->foreground_fd = fd[0];
	  return ps;
	}
    }
  else
    {
      /*
       * Background Process
       */

      /* Ignore most signals (the parent will receive them) */
      set_signals ();

      /* Let msg know that we forked */
      msg_forked ();

      /* close all parent fds except our socket back to parent */
      close_fds_except (fd[1]);

      /* no blocking on control channel back to parent */
      set_nonblock (fd[1]);

      /* execute the event loop */
      port_share_proxy (hostaddr, port, fd[1]);

      openvpn_close_socket (fd[1]);

      exit (0);
      return 0; /* NOTREACHED */
    }

 error:
  port_share_close (ps);
  return NULL;
}

void
port_share_close (struct port_share *ps)
{
  if (ps)
    {
      if (ps->foreground_fd >= 0)
	{
	  /* tell background process to exit */
	  port_share_sendmsg (ps->foreground_fd, COMMAND_EXIT, NULL, SOCKET_UNDEFINED);

	  /* wait for background process to exit */
	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: waiting for background process to exit");
	  if (ps->background_pid > 0)
	    waitpid (ps->background_pid, NULL, 0);
	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: background process exited");

	  openvpn_close_socket (ps->foreground_fd);
	  ps->foreground_fd = -1;
	}

      free (ps);
    }
}

void
port_share_abort (struct port_share *ps)
{
  if (ps)
    {
      /* tell background process to exit */
      if (ps->foreground_fd >= 0)
	{
	  send_control (ps->foreground_fd, COMMAND_EXIT);
	  openvpn_close_socket (ps->foreground_fd);
	  ps->foreground_fd = -1;
	}
    }
}

/*
 * Given either the first 2 or 3 bytes of an initial client -> server
 * data payload, return true if the protocol is that of an OpenVPN
 * client attempting to connect with an OpenVPN server.
 */
bool
is_openvpn_protocol (const struct buffer *buf)
{
  const unsigned char *p = (const unsigned char *) BSTR (buf);
  const int len = BLEN (buf);
  if (len >= 3)
    {
      return p[0] == 0
	&& p[1] >= 14
	&& p[2] == (P_CONTROL_HARD_RESET_CLIENT_V2<<P_OPCODE_SHIFT);
    }
  else if (len >= 2)
    {
      return p[0] == 0 && p[1] >= 14;
    }
  else
    return true;
}

/*
 * Called from the foreground process.  Send a message to the background process that it
 * should proxy the TCP client on sd to the host/port defined in the initial port_share_open
 * call.
 */
void
port_share_redirect (struct port_share *ps, const struct buffer *head, socket_descriptor_t sd)
{
  if (ps)
    port_share_sendmsg (ps->foreground_fd, COMMAND_REDIRECT, head, sd);
}

#endif