This is the start of the BETA21 branch.

It includes the --topology feature, and
TAP-Win32 driver changes to allow
non-admin access.



git-svn-id: http://svn.openvpn.net/projects/openvpn/branches/BETA21/openvpn@580 e7ae566f-a301-0410-adde-c780ea21d3b5

1 files changed, 1402 insertions, 0 deletions

diff --git a/forward.c b/forward.c
new file mode 100644
index 0000000..4c0aff8
--- /dev/null
+++ b/forward.c
@@ -0,0 +1,1402 @@
+/*
+ *  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) 2002-2005 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"
+
+#include "forward.h"
+#include "init.h"
+#include "push.h"
+#include "gremlin.h"
+#include "mss.h"
+#include "event.h"
+
+#include "memdbg.h"
+
+#include "forward-inline.h"
+#include "occ-inline.h"
+#include "ping-inline.h"
+
+/* show event wait debugging info */
+
+#ifdef ENABLE_DEBUG
+
+const char *
+wait_status_string (struct context *c, struct gc_arena *gc)
+{
+  struct buffer out = alloc_buf_gc (64, gc);
+  buf_printf (&out, "I/O WAIT %s|%s|%s|%s %s",
+	      tun_stat (c->c1.tuntap, EVENT_READ, gc),
+	      tun_stat (c->c1.tuntap, EVENT_WRITE, gc),
+	      socket_stat (c->c2.link_socket, EVENT_READ, gc),
+	      socket_stat (c->c2.link_socket, EVENT_WRITE, gc),
+	      tv_string (&c->c2.timeval, gc));
+  return BSTR (&out);
+}
+
+void
+show_wait_status (struct context *c)
+{
+  struct gc_arena gc = gc_new ();
+  dmsg (D_EVENT_WAIT, "%s", wait_status_string (c, &gc));
+  gc_free (&gc);
+}
+
+#endif
+
+/*
+ * In TLS mode, let TLS level respond to any control-channel
+ * packets which were received, or prepare any packets for
+ * transmission.
+ *
+ * tmp_int is purely an optimization that allows us to call
+ * tls_multi_process less frequently when there's not much
+ * traffic on the control-channel.
+ *
+ */
+#if defined(USE_CRYPTO) && defined(USE_SSL)
+void
+check_tls_dowork (struct context *c)
+{
+  interval_t wakeup = BIG_TIMEOUT;
+
+  if (interval_test (&c->c2.tmp_int))
+    {
+      if (tls_multi_process
+	  (c->c2.tls_multi, &c->c2.to_link, &c->c2.to_link_addr,
+	   get_link_socket_info (c), &wakeup))
+	{
+	  update_time ();
+	  interval_action (&c->c2.tmp_int);
+	}
+
+      interval_future_trigger (&c->c2.tmp_int, wakeup);
+    }
+
+  interval_schedule_wakeup (&c->c2.tmp_int, &wakeup);
+
+  if (wakeup)
+    context_reschedule_sec (c, wakeup);
+}
+#endif
+
+#if defined(USE_CRYPTO) && defined(USE_SSL)
+
+void
+check_tls_errors_co (struct context *c)
+{
+  msg (D_STREAM_ERRORS, "Fatal TLS error (check_tls_errors_co), restarting");
+  c->sig->signal_received = c->c2.tls_exit_signal; /* SOFT-SIGUSR1 -- TLS error */
+  c->sig->signal_text = "tls-error";
+}
+
+void
+check_tls_errors_nco (struct context *c)
+{
+  c->sig->signal_received = c->c2.tls_exit_signal; /* SOFT-SIGUSR1 -- TLS error */
+  c->sig->signal_text = "tls-error";
+}
+
+#endif
+
+#if P2MP
+
+/*
+ * Handle incoming configuration
+ * messages on the control channel.
+ */
+void
+check_incoming_control_channel_dowork (struct context *c)
+{
+  const int len = tls_test_payload_len (c->c2.tls_multi);
+  if (len)
+    {
+      struct gc_arena gc = gc_new ();
+      struct buffer buf = alloc_buf_gc (len, &gc);
+      if (tls_rec_payload (c->c2.tls_multi, &buf))
+	{
+	  /* force null termination of message */
+	  buf_null_terminate (&buf);
+
+	  /* enforce character class restrictions */
+	  string_mod (BSTR (&buf), CC_PRINT, CC_CRLF, 0);
+
+	  if (buf_string_match_head_str (&buf, "AUTH_FAILED"))
+	    receive_auth_failed (c, &buf);
+	  else if (buf_string_match_head_str (&buf, "PUSH_"))
+	    incoming_push_message (c, &buf);
+	  else
+	    msg (D_PUSH_ERRORS, "WARNING: Received unknown control message: %s", BSTR (&buf));
+	}
+      else
+	{
+	  msg (D_PUSH_ERRORS, "WARNING: Receive control message failed");
+	}
+
+      gc_free (&gc);
+    }
+}
+
+/*
+ * Periodically resend PUSH_REQUEST until PUSH message received
+ */
+void
+check_push_request_dowork (struct context *c)
+{
+  send_push_request (c);
+}
+
+#endif
+
+/*
+ * Things that need to happen immediately after connection initiation should go here.
+ */
+void
+check_connection_established_dowork (struct context *c)
+{
+  if (event_timeout_trigger (&c->c2.wait_for_connect, &c->c2.timeval, ETT_DEFAULT))
+    {
+      if (CONNECTION_ESTABLISHED (c))
+	{
+#if P2MP
+	  /* if --pull was specified, send a push request to server */
+	  if (c->c2.tls_multi && c->options.pull)
+	    {
+#ifdef ENABLE_MANAGEMENT
+	      if (management)
+		{
+		  management_set_state (management,
+					OPENVPN_STATE_GET_CONFIG,
+					NULL,
+					0);
+		}
+#endif
+	      send_push_request (c);
+
+	      /* if no reply, try again in 5 sec */
+	      event_timeout_init (&c->c2.push_request_interval, 5, now);
+	      reset_coarse_timers (c);
+	    }
+	  else
+#endif
+	    {
+	      do_up (c, false, 0);
+	    }
+
+	  event_timeout_clear (&c->c2.wait_for_connect);
+	}
+    }
+}
+
+/*
+ * Send a string to remote over the TLS control channel.
+ * Used for push/pull messages, passing username/password,
+ * etc.
+ */
+bool
+send_control_channel_string (struct context *c, const char *str, int msglevel)
+{
+#if defined(USE_CRYPTO) && defined(USE_SSL)
+
+  if (c->c2.tls_multi) {
+    bool stat;
+
+    /* buffered cleartext write onto TLS control channel */
+    stat = tls_send_payload (c->c2.tls_multi, (uint8_t*) str, strlen (str) + 1);
+
+    /* reschedule tls_multi_process */
+    interval_action (&c->c2.tmp_int);
+    context_immediate_reschedule (c); /* ZERO-TIMEOUT */
+
+    msg (msglevel, "SENT CONTROL [%s]: '%s' (status=%d)",
+	 tls_common_name (c->c2.tls_multi, false),
+	 str,
+	 (int) stat);
+
+    return stat;
+  }
+#endif
+  return true;
+}
+
+/*
+ * Add routes.
+ */
+
+static void
+check_add_routes_action (struct context *c, const bool errors)
+{
+  do_route (&c->options, c->c1.route_list, c->c1.tuntap, c->c1.plugins, c->c2.es);
+  update_time ();
+  event_timeout_clear (&c->c2.route_wakeup);
+  event_timeout_clear (&c->c2.route_wakeup_expire);
+  initialization_sequence_completed (c, errors ? ISC_ERRORS : 0); /* client/p2p --route-delay was defined */
+}
+
+void
+check_add_routes_dowork (struct context *c)
+{
+  if (test_routes (c->c1.route_list, c->c1.tuntap))
+    {
+      check_add_routes_action (c, false);
+    }
+  else if (event_timeout_trigger (&c->c2.route_wakeup_expire, &c->c2.timeval, ETT_DEFAULT))
+    {
+      check_add_routes_action (c, true);
+    }
+  else
+    {
+      msg (D_ROUTE, "Route: Waiting for TUN/TAP interface to come up...");
+      if (c->c2.route_wakeup.n != 1)
+	event_timeout_init (&c->c2.route_wakeup, 1, now);
+    }
+}
+
+/*
+ * Should we exit due to inactivity timeout?
+ */
+void
+check_inactivity_timeout_dowork (struct context *c)
+{
+  msg (M_INFO, "Inactivity timeout (--inactive), exiting");
+  c->sig->signal_received = SIGTERM;
+  c->sig->signal_text = "inactive";
+}
+
+#if P2MP
+
+/*
+ * Schedule a SIGTERM n_seconds from now.
+ */
+void
+schedule_exit (struct context *c, const int n_seconds)
+{
+  update_time ();
+  reset_coarse_timers (c);
+  event_timeout_init (&c->c2.scheduled_exit, n_seconds, now);
+  msg (D_SCHED_EXIT, "Delayed exit in %d seconds", n_seconds);
+}
+
+/*
+ * Scheduled exit?
+ */
+void
+check_scheduled_exit_dowork (struct context *c)
+{
+  c->sig->signal_received = SIGTERM;
+  c->sig->signal_text = "delayed-exit";
+}
+
+#endif
+
+/*
+ * Should we write timer-triggered status file.
+ */
+void
+check_status_file_dowork (struct context *c)
+{
+  if (c->c1.status_output)
+    print_status (c, c->c1.status_output);
+}
+
+#ifdef ENABLE_FRAGMENT
+/*
+ * Should we deliver a datagram fragment to remote?
+ */
+void
+check_fragment_dowork (struct context *c)
+{
+  struct link_socket_info *lsi = get_link_socket_info (c);
+
+  /* OS MTU Hint? */
+  if (lsi->mtu_changed && c->c2.ipv4_tun)
+    {
+      frame_adjust_path_mtu (&c->c2.frame_fragment, c->c2.link_socket->mtu,
+			     c->options.proto);
+      lsi->mtu_changed = false;
+    }
+
+  if (fragment_outgoing_defined (c->c2.fragment))
+    {
+      if (!c->c2.to_link.len)
+	{
+	  /* encrypt a fragment for output to TCP/UDP port */
+	  ASSERT (fragment_ready_to_send (c->c2.fragment, &c->c2.buf, &c->c2.frame_fragment));
+	  encrypt_sign (c, false);
+	}
+    }
+
+  fragment_housekeeping (c->c2.fragment, &c->c2.frame_fragment, &c->c2.timeval);
+}
+#endif
+
+/*
+ * Buffer reallocation, for use with null encryption.
+ */
+static inline void
+buffer_turnover (const uint8_t *orig_buf, struct buffer *dest_stub, struct buffer *src_stub, struct buffer *storage)
+{
+  if (orig_buf == src_stub->data && src_stub->data != storage->data)
+    {
+      buf_assign (storage, src_stub);
+      *dest_stub = *storage;
+    }
+  else
+    {
+      *dest_stub = *src_stub;
+    }
+}
+
+/*
+ * Compress, fragment, encrypt and HMAC-sign an outgoing packet.
+ * Input: c->c2.buf
+ * Output: c->c2.to_link
+ */
+void
+encrypt_sign (struct context *c, bool comp_frag)
+{
+  struct context_buffers *b = c->c2.buffers;
+  const uint8_t *orig_buf = c->c2.buf.data;
+
+#if P2MP_SERVER
+  /*
+   * Drop non-TLS outgoing packet if client-connect script/plugin
+   * has not yet succeeded.
+   */
+  if (c->c2.context_auth != CAS_SUCCEEDED)
+    c->c2.buf.len = 0;
+#endif
+
+  if (comp_frag)
+    {
+#ifdef USE_LZO
+      /* Compress the packet. */
+      if (c->options.comp_lzo)
+	lzo_compress (&c->c2.buf, b->lzo_compress_buf, &c->c2.lzo_compwork, &c->c2.frame);
+#endif
+#ifdef ENABLE_FRAGMENT
+      if (c->c2.fragment)
+	fragment_outgoing (c->c2.fragment, &c->c2.buf, &c->c2.frame_fragment);
+#endif
+    }
+
+#ifdef USE_CRYPTO
+#ifdef USE_SSL
+  /*
+   * If TLS mode, get the key we will use to encrypt
+   * the packet.
+   */
+  if (c->c2.tls_multi)
+    {
+      /*tls_mutex_lock (c->c2.tls_multi);*/
+      tls_pre_encrypt (c->c2.tls_multi, &c->c2.buf, &c->c2.crypto_options);
+    }
+#endif
+
+  /*
+   * Encrypt the packet and write an optional
+   * HMAC signature.
+   */
+  openvpn_encrypt (&c->c2.buf, b->encrypt_buf, &c->c2.crypto_options, &c->c2.frame);
+#endif
+  /*
+   * Get the address we will be sending the packet to.
+   */
+  link_socket_get_outgoing_addr (&c->c2.buf, get_link_socket_info (c),
+				 &c->c2.to_link_addr);
+#ifdef USE_CRYPTO
+#ifdef USE_SSL
+  /*
+   * In TLS mode, prepend the appropriate one-byte opcode
+   * to the packet which identifies it as a data channel
+   * packet and gives the low-permutation version of
+   * the key-id to the recipient so it knows which
+   * decrypt key to use.
+   */
+  if (c->c2.tls_multi)
+    {
+      tls_post_encrypt (c->c2.tls_multi, &c->c2.buf);
+      /*tls_mutex_unlock (c->c2.tls_multi);*/
+    }
+#endif
+#endif
+
+  /* if null encryption, copy result to read_tun_buf */
+  buffer_turnover (orig_buf, &c->c2.to_link, &c->c2.buf, &b->read_tun_buf);
+}
+
+/*
+ * Coarse timers work to 1 second resolution.
+ */
+static void
+process_coarse_timers (struct context *c)
+{
+#ifdef USE_CRYPTO
+  /* flush current packet-id to file once per 60
+     seconds if --replay-persist was specified */
+  check_packet_id_persist_flush (c);
+#endif
+
+  /* should we update status file? */
+  check_status_file (c);
+
+  /* process connection establishment items */
+  check_connection_established (c);
+
+#if P2MP
+  /* see if we should send a push_request in response to --pull */
+  check_push_request (c);
+#endif
+
+  /* process --route options */
+  check_add_routes (c);
+
+  /* possibly exit due to --inactive */
+  check_inactivity_timeout (c);
+  if (c->sig->signal_received)
+    return;
+
+  /* restart if ping not received */
+  check_ping_restart (c);
+  if (c->sig->signal_received)
+    return;
+
+#if P2MP
+  check_scheduled_exit (c);
+  if (c->sig->signal_received)
+    return;
+#endif
+
+#ifdef ENABLE_OCC
+  /* Should we send an OCC_REQUEST message? */
+  check_send_occ_req (c);
+
+  /* Should we send an MTU load test? */
+  check_send_occ_load_test (c);
+
+  /* Should we send an OCC_EXIT message to remote? */
+  if (c->c2.explicit_exit_notification_time_wait)
+    process_explicit_exit_notification_timer_wakeup (c);
+#endif
+
+  /* Should we ping the remote? */
+  check_ping_send (c);
+}
+
+static void
+check_coarse_timers_dowork (struct context *c)
+{
+  const struct timeval save = c->c2.timeval;
+  c->c2.timeval.tv_sec = BIG_TIMEOUT;
+  c->c2.timeval.tv_usec = 0;
+  process_coarse_timers (c);
+  c->c2.coarse_timer_wakeup = now + c->c2.timeval.tv_sec; 
+
+  dmsg (D_INTERVAL, "TIMER: coarse timer wakeup %d seconds", (int) c->c2.timeval.tv_sec);
+
+  /* Is the coarse timeout NOT the earliest one? */
+  if (c->c2.timeval.tv_sec > save.tv_sec)
+    c->c2.timeval = save;
+}
+
+static inline void
+check_coarse_timers (struct context *c)
+{
+  const time_t local_now = now;
+  if (local_now >= c->c2.coarse_timer_wakeup)
+    check_coarse_timers_dowork (c);
+  else
+    context_reschedule_sec (c, c->c2.coarse_timer_wakeup - local_now);
+}
+
+static void
+check_timeout_random_component_dowork (struct context *c)
+{
+  const int update_interval = 10; /* seconds */
+  c->c2.update_timeout_random_component = now + update_interval;
+  c->c2.timeout_random_component.tv_usec = (time_t) get_random () & 0x0003FFFF;
+  c->c2.timeout_random_component.tv_sec = 0;
+
+  dmsg (D_INTERVAL, "RANDOM USEC=%d", (int) c->c2.timeout_random_component.tv_usec);
+}
+
+static inline void
+check_timeout_random_component (struct context *c)
+{
+  if (now >= c->c2.update_timeout_random_component)
+    check_timeout_random_component_dowork (c);
+  if (c->c2.timeval.tv_sec >= 1)
+    tv_add (&c->c2.timeval, &c->c2.timeout_random_component);
+}
+
+#ifdef ENABLE_SOCKS
+
+/*
+ * Handle addition and removal of the 10-byte Socks5 header
+ * in UDP packets.
+ */
+
+static inline void
+socks_postprocess_incoming_link (struct context *c)
+{
+  if (c->c2.link_socket->socks_proxy && c->c2.link_socket->info.proto == PROTO_UDPv4)
+    socks_process_incoming_udp (&c->c2.buf, &c->c2.from);
+}
+
+static inline void
+socks_preprocess_outgoing_link (struct context *c,
+				struct sockaddr_in **to_addr,
+				int *size_delta)
+{
+  if (c->c2.link_socket->socks_proxy && c->c2.link_socket->info.proto == PROTO_UDPv4)
+    {
+      *size_delta += socks_process_outgoing_udp (&c->c2.to_link, &c->c2.to_link_addr);
+      *to_addr = &c->c2.link_socket->socks_relay;
+    }
+}
+
+/* undo effect of socks_preprocess_outgoing_link */
+static inline void
+link_socket_write_post_size_adjust (int *size,
+				    int size_delta,
+				    struct buffer *buf)
+{
+  if (size_delta > 0 && *size > size_delta)
+    {
+      *size -= size_delta;
+      if (!buf_advance (buf, size_delta))
+	*size = 0;
+    }
+}
+#endif
+
+/*
+ * Output: c->c2.buf
+ */
+
+void
+read_incoming_link (struct context *c)
+{
+  /*
+   * Set up for recvfrom call to read datagram
+   * sent to our TCP/UDP port.
+   */
+  int status;
+
+  perf_push (PERF_READ_IN_LINK);
+
+  ASSERT (!c->c2.to_tun.len);
+
+  c->c2.buf = c->c2.buffers->read_link_buf;
+  ASSERT (buf_init (&c->c2.buf, FRAME_HEADROOM_ADJ (&c->c2.frame, FRAME_HEADROOM_MARKER_READ_LINK)));
+  status = link_socket_read (c->c2.link_socket, &c->c2.buf, MAX_RW_SIZE_LINK (&c->c2.frame), &c->c2.from);
+
+  if (socket_connection_reset (c->c2.link_socket, status))
+    {
+      /* received a disconnect from a connection-oriented protocol */
+      if (c->options.inetd)
+	{
+	  c->sig->signal_received = SIGTERM;
+	  msg (D_STREAM_ERRORS, "Connection reset, inetd/xinetd exit [%d]", status);
+	}
+      else
+	{
+	  c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- TCP connection reset */
+	  msg (D_STREAM_ERRORS, "Connection reset, restarting [%d]", status);
+	}
+      c->sig->signal_text = "connection-reset";
+      perf_pop ();
+      return;
+    }
+
+  /* check recvfrom status */
+  check_status (status, "read", c->c2.link_socket, NULL);
+
+#ifdef ENABLE_SOCKS
+  /* Remove socks header if applicable */
+  socks_postprocess_incoming_link (c);
+#endif
+
+  perf_pop ();
+}
+
+/*
+ * Input:  c->c2.buf
+ * Output: c->c2.to_tun
+ */
+
+void
+process_incoming_link (struct context *c)
+{
+  struct gc_arena gc = gc_new ();
+  bool decrypt_status;
+  struct link_socket_info *lsi = get_link_socket_info (c);
+  const uint8_t *orig_buf = c->c2.buf.data;
+
+  perf_push (PERF_PROC_IN_LINK);
+
+  if (c->c2.buf.len > 0)
+    {
+      c->c2.link_read_bytes += c->c2.buf.len;
+      c->c2.original_recv_size = c->c2.buf.len;
+    }
+  else
+    c->c2.original_recv_size = 0;
+
+#ifdef ENABLE_DEBUG
+  /* take action to corrupt packet if we are in gremlin test mode */
+  if (c->options.gremlin) {
+    if (!ask_gremlin (c->options.gremlin))
+      c->c2.buf.len = 0;
+    corrupt_gremlin (&c->c2.buf, c->options.gremlin);
+  }
+#endif
+
+  /* log incoming packet */
+#ifdef LOG_RW
+  if (c->c2.log_rw)
+    fprintf (stderr, "R");
+#endif
+  msg (D_LINK_RW, "%s READ [%d] from %s: %s",
+       proto2ascii (lsi->proto, true),
+       BLEN (&c->c2.buf),
+       print_sockaddr (&c->c2.from, &gc),
+       PROTO_DUMP (&c->c2.buf, &gc));
+
+  /*
+   * Good, non-zero length packet received.
+   * Commence multi-stage processing of packet,
+   * such as authenticate, decrypt, decompress.
+   * If any stage fails, it sets buf.len to 0 or -1,
+   * telling downstream stages to ignore the packet.
+   */
+  if (c->c2.buf.len > 0)
+    {
+      if (!link_socket_verify_incoming_addr (&c->c2.buf, lsi, &c->c2.from))
+	link_socket_bad_incoming_addr (&c->c2.buf, lsi, &c->c2.from);
+
+#ifdef USE_CRYPTO
+#ifdef USE_SSL
+      if (c->c2.tls_multi)
+	{
+	  /*
+	   * If tls_pre_decrypt returns true, it means the incoming
+	   * packet was a good TLS control channel packet.  If so, TLS code
+	   * will deal with the packet and set buf.len to 0 so downstream
+	   * stages ignore it.
+	   *
+	   * If the packet is a data channel packet, tls_pre_decrypt
+	   * will load crypto_options with the correct encryption key
+	   * and return false.
+	   */
+	  /*tls_mutex_lock (c->c2.tls_multi);*/
+	  if (tls_pre_decrypt (c->c2.tls_multi, &c->c2.from, &c->c2.buf, &c->c2.crypto_options))
+	    {
+	      interval_action (&c->c2.tmp_int);
+
+	      /* reset packet received timer if TLS packet */
+	      if (c->options.ping_rec_timeout)
+		event_timeout_reset (&c->c2.ping_rec_interval);
+	    }
+	}
+#if P2MP_SERVER
+      /*
+       * Drop non-TLS packet if client-connect script/plugin has not
+       * yet succeeded.
+       */
+      if (c->c2.context_auth != CAS_SUCCEEDED)
+	c->c2.buf.len = 0;
+#endif
+#endif /* USE_SSL */
+
+      /* authenticate and decrypt the incoming packet */
+      decrypt_status = openvpn_decrypt (&c->c2.buf, c->c2.buffers->decrypt_buf, &c->c2.crypto_options, &c->c2.frame);
+
+#ifdef USE_SSL
+      if (c->c2.tls_multi)
+	{
+	  /*tls_mutex_unlock (c->c2.tls_multi);*/
+	}
+#endif
+      
+      if (!decrypt_status && link_socket_connection_oriented (c->c2.link_socket))
+	{
+	  /* decryption errors are fatal in TCP mode */
+	  c->sig->signal_received = SIGUSR1; /* SOFT-SIGUSR1 -- decryption error in TCP mode */
+	  c->sig->signal_text = "decryption-error";
+	  msg (D_STREAM_ERRORS, "Fatal decryption error (process_incoming_link), restarting");
+	  goto done;
+	}
+
+#endif /* USE_CRYPTO */
+
+#ifdef ENABLE_FRAGMENT
+      if (c->c2.fragment)
+	fragment_incoming (c->c2.fragment, &c->c2.buf, &c->c2.frame_fragment);
+#endif
+
+#ifdef USE_LZO
+      /* decompress the incoming packet */
+      if (c->options.comp_lzo)
+	lzo_decompress (&c->c2.buf, c->c2.buffers->lzo_decompress_buf, &c->c2.lzo_compwork, &c->c2.frame);
+#endif
+      /*
+       * Set our "official" outgoing address, since
+       * if buf.len is non-zero, we know the packet
+       * authenticated.  In TLS mode we do nothing
+       * because TLS mode takes care of source address
+       * authentication.
+       *
+       * Also, update the persisted version of our packet-id.
+       */
+      if (!TLS_MODE (c))
+	link_socket_set_outgoing_addr (&c->c2.buf, lsi, &c->c2.from, NULL, c->c2.es);
+
+      /* reset packet received timer */
+      if (c->options.ping_rec_timeout && c->c2.buf.len > 0)
+	event_timeout_reset (&c->c2.ping_rec_interval);
+
+      /* increment authenticated receive byte count */
+      if (c->c2.buf.len > 0)
+	{
+	  c->c2.link_read_bytes_auth += c->c2.buf.len;
+	  c->c2.max_recv_size_local = max_int (c->c2.original_recv_size, c->c2.max_recv_size_local);
+	}
+
+      /* Did we just receive an openvpn ping packet? */
+      if (is_ping_msg (&c->c2.buf))
+	{
+	  dmsg (D_PACKET_CONTENT, "RECEIVED PING PACKET");
+	  c->c2.buf.len = 0; /* drop packet */
+	}
+
+#ifdef ENABLE_OCC
+      /* Did we just receive an OCC packet? */
+      if (is_occ_msg (&c->c2.buf))
+	process_received_occ_msg (c);
+#endif
+
+      buffer_turnover (orig_buf, &c->c2.to_tun, &c->c2.buf, &c->c2.buffers->read_link_buf);
+
+      /* to_tun defined + unopened tuntap can cause deadlock */
+      if (!tuntap_defined (c->c1.tuntap))
+	c->c2.to_tun.len = 0;
+    }
+  else
+    {
+      buf_reset (&c->c2.to_tun);
+    }
+ done:
+  perf_pop ();
+  gc_free (&gc);
+}
+
+/*
+ * Output: c->c2.buf
+ */
+
+void
+read_incoming_tun (struct context *c)
+{
+  perf_push (PERF_READ_IN_TUN);
+
+  /*
+   * Setup for read() call on TUN/TAP device.
+   */
+  ASSERT (!c->c2.to_link.len);
+
+  c->c2.buf = c->c2.buffers->read_tun_buf;
+#ifdef TUN_PASS_BUFFER
+  read_tun_buffered (c->c1.tuntap, &c->c2.buf, MAX_RW_SIZE_TUN (&c->c2.frame));
+#else
+  ASSERT (buf_init (&c->c2.buf, FRAME_HEADROOM (&c->c2.frame)));
+  ASSERT (buf_safe (&c->c2.buf, MAX_RW_SIZE_TUN (&c->c2.frame)));
+  c->c2.buf.len = read_tun (c->c1.tuntap, BPTR (&c->c2.buf), MAX_RW_SIZE_TUN (&c->c2.frame));
+#endif
+
+  /* Was TUN/TAP interface stopped? */
+  if (tuntap_stop (c->c2.buf.len))
+    {
+      c->sig->signal_received = SIGTERM;
+      c->sig->signal_text = "tun-stop";
+      msg (M_INFO, "TUN/TAP interface has been stopped, exiting");
+      perf_pop ();
+      return;		  
+    }
+
+  /* Check the status return from read() */
+  check_status (c->c2.buf.len, "read from TUN/TAP", NULL, c->c1.tuntap);
+
+  perf_pop ();
+}
+
+/*
+ * Input:  c->c2.buf
+ * Output: c->c2.to_link
+ */
+
+void
+process_incoming_tun (struct context *c)
+{
+  struct gc_arena gc = gc_new ();
+
+  perf_push (PERF_PROC_IN_TUN);
+
+  if (c->c2.buf.len > 0)
+    c->c2.tun_read_bytes += c->c2.buf.len;
+
+#ifdef LOG_RW
+  if (c->c2.log_rw)
+    fprintf (stderr, "r");
+#endif
+
+  /* Show packet content */
+  dmsg (D_TUN_RW, "TUN READ [%d]: %s md5=%s",
+       BLEN (&c->c2.buf),
+       format_hex (BPTR (&c->c2.buf), BLEN (&c->c2.buf), 80, &gc),
+       MD5SUM (BPTR (&c->c2.buf), BLEN (&c->c2.buf), &gc));
+
+  if (c->c2.buf.len > 0)
+    {
+      /*
+       * The --passtos and --mssfix options require
+       * us to examine the IPv4 header.
+       */
+      process_ipv4_header (c, PIPV4_PASSTOS|PIPV4_MSSFIX, &c->c2.buf);
+      encrypt_sign (c, true);
+    }
+  else
+    {
+      buf_reset (&c->c2.to_link);
+    }
+  perf_pop ();
+  gc_free (&gc);
+}
+
+void
+process_ipv4_header (struct context *c, unsigned int flags, struct buffer *buf)
+{
+  if (!c->options.mssfix)
+    flags &= ~PIPV4_MSSFIX;
+#if PASSTOS_CAPABILITY
+  if (!c->options.passtos)
+    flags &= ~PIPV4_PASSTOS;
+#endif
+
+  if (buf->len > 0)
+    {
+      /*
+       * The --passtos and --mssfix options require
+       * us to examine the IPv4 header.
+       */
+#if PASSTOS_CAPABILITY
+      if (flags & (PIPV4_PASSTOS|PIPV4_MSSFIX))
+#else
+      if (flags & PIPV4_MSSFIX)
+#endif
+	{
+	  struct buffer ipbuf = *buf;
+	  if (is_ipv4 (TUNNEL_TYPE (c->c1.tuntap), &ipbuf))
+	    {
+#if PASSTOS_CAPABILITY
+	      /* extract TOS from IP header */
+	      if (flags & PIPV4_PASSTOS)
+		link_socket_extract_tos (c->c2.link_socket, &ipbuf);
+#endif
+			  
+	      /* possibly alter the TCP MSS */
+	      if (flags & PIPV4_MSSFIX)
+		mss_fixup (&ipbuf, MTU_TO_MSS (TUN_MTU_SIZE_DYNAMIC (&c->c2.frame)));
+	    }
+	}
+    }
+}
+
+/*
+ * Input: c->c2.to_link
+ */
+
+void
+process_outgoing_link (struct context *c)
+{
+  struct gc_arena gc = gc_new ();
+
+  perf_push (PERF_PROC_OUT_LINK);
+
+  if (c->c2.to_link.len > 0 && c->c2.to_link.len <= EXPANDED_SIZE (&c->c2.frame))
+    {
+      /*
+       * Setup for call to send/sendto which will send
+       * packet to remote over the TCP/UDP port.
+       */
+      int size = 0;
+      ASSERT (addr_defined (&c->c2.to_link_addr));
+
+#ifdef ENABLE_DEBUG
+      /* In gremlin-test mode, we may choose to drop this packet */
+      if (!c->options.gremlin || ask_gremlin (c->options.gremlin))
+#endif
+	{
+	  /*
+	   * Let the traffic shaper know how many bytes
+	   * we wrote.
+	   */
+#ifdef HAVE_GETTIMEOFDAY
+	  if (c->options.shaper)
+	    shaper_wrote_bytes (&c->c2.shaper, BLEN (&c->c2.to_link)
+				+ datagram_overhead (c->options.proto));
+#endif
+	  /*
+	   * Let the pinger know that we sent a packet.
+	   */
+	  if (c->options.ping_send_timeout)
+	    event_timeout_reset (&c->c2.ping_send_interval);
+
+#if PASSTOS_CAPABILITY
+	  /* Set TOS */
+	  link_socket_set_tos (c->c2.link_socket);
+#endif
+
+	  /* Log packet send */
+#ifdef LOG_RW
+	  if (c->c2.log_rw)
+	    fprintf (stderr, "W");
+#endif
+	  msg (D_LINK_RW, "%s WRITE [%d] to %s: %s",
+	       proto2ascii (c->c2.link_socket->info.proto, true),
+	       BLEN (&c->c2.to_link),
+	       print_sockaddr (&c->c2.to_link_addr, &gc),
+	       PROTO_DUMP (&c->c2.to_link, &gc));
+
+	  /* Packet send complexified by possible Socks5 usage */
+	  {
+	    struct sockaddr_in *to_addr = &c->c2.to_link_addr;
+#ifdef ENABLE_SOCKS
+	    int size_delta = 0;
+#endif
+
+#ifdef ENABLE_SOCKS
+	    /* If Socks5 over UDP, prepend header */
+	    socks_preprocess_outgoing_link (c, &to_addr, &size_delta);
+#endif
+	    /* Send packet */
+	    size = link_socket_write (c->c2.link_socket, &c->c2.to_link, to_addr);
+
+#ifdef ENABLE_SOCKS
+	    /* Undo effect of prepend */
+	    link_socket_write_post_size_adjust (&size, size_delta, &c->c2.to_link);
+#endif
+	  }
+
+	  if (size > 0)
+	    {
+	      c->c2.max_send_size_local = max_int (size, c->c2.max_send_size_local);
+	      c->c2.link_write_bytes += size;
+	    }
+	}
+
+      /* Check return status */
+      check_status (size, "write", c->c2.link_socket, NULL);
+
+      if (size > 0)
+	{
+	  /* Did we write a different size packet than we intended? */
+	  if (size != BLEN (&c->c2.to_link))
+	    msg (D_LINK_ERRORS,
+		 "TCP/UDP packet was truncated/expanded on write to %s (tried=%d,actual=%d)",
+		 print_sockaddr (&c->c2.to_link_addr, &gc),
+		 BLEN (&c->c2.to_link),
+		 size);
+	}
+    }
+  else
+    {
+      if (c->c2.to_link.len > 0)
+	msg (D_LINK_ERRORS, "TCP/UDP packet too large on write to %s (tried=%d,max=%d)",
+	     print_sockaddr (&c->c2.to_link_addr, &gc),
+	     c->c2.to_link.len,
+	     EXPANDED_SIZE (&c->c2.frame));
+    }
+
+  buf_reset (&c->c2.to_link);
+
+  perf_pop ();
+  gc_free (&gc);
+}
+
+/*
+ * Input: c->c2.to_tun
+ */
+
+void
+process_outgoing_tun (struct context *c)
+{
+  struct gc_arena gc = gc_new ();
+
+  perf_push (PERF_PROC_OUT_TUN);
+
+  /*
+   * Set up for write() call to TUN/TAP
+   * device.
+   */
+  ASSERT (c->c2.to_tun.len > 0);
+
+  /*
+   * The --mssfix option requires
+   * us to examine the IPv4 header.
+   */
+  process_ipv4_header (c, PIPV4_MSSFIX, &c->c2.to_tun);
+
+  if (c->c2.to_tun.len <= MAX_RW_SIZE_TUN (&c->c2.frame))
+    {
+      /*
+       * Write to TUN/TAP device.
+       */
+      int size;
+
+#ifdef LOG_RW
+      if (c->c2.log_rw)
+	fprintf (stderr, "w");
+#endif
+      dmsg (D_TUN_RW, "TUN WRITE [%d]: %s md5=%s",
+	   BLEN (&c->c2.to_tun),
+	   format_hex (BPTR (&c->c2.to_tun), BLEN (&c->c2.to_tun), 80, &gc),
+	   MD5SUM (BPTR (&c->c2.to_tun), BLEN (&c->c2.to_tun), &gc));
+
+#ifdef TUN_PASS_BUFFER
+      size = write_tun_buffered (c->c1.tuntap, &c->c2.to_tun);
+#else
+      size = write_tun (c->c1.tuntap, BPTR (&c->c2.to_tun), BLEN (&c->c2.to_tun));
+#endif
+
+      if (size > 0)
+	c->c2.tun_write_bytes += size;
+      check_status (size, "write to TUN/TAP", NULL, c->c1.tuntap);
+
+      /* check written packet size */
+      if (size > 0)
+	{
+	  /* Did we write a different size packet than we intended? */
+	  if (size != BLEN (&c->c2.to_tun))
+	    msg (D_LINK_ERRORS,
+		 "TUN/TAP packet was destructively fragmented on write to %s (tried=%d,actual=%d)",
+		 c->c1.tuntap->actual_name,
+		 BLEN (&c->c2.to_tun),
+		 size);
+	}
+    }
+  else
+    {
+      /*
+       * This should never happen, probably indicates some kind
+       * of MTU mismatch.
+       */
+      msg (D_LINK_ERRORS, "tun packet too large on write (tried=%d,max=%d)",
+	   c->c2.to_tun.len,
+	   MAX_RW_SIZE_TUN (&c->c2.frame));
+    }
+
+  /*
+   * Putting the --inactive timeout reset here, ensures that we will timeout
+   * if the remote goes away, even if we are trying to send data to the
+   * remote and failing.
+   */
+  register_activity (c);
+
+  buf_reset (&c->c2.to_tun);
+
+  perf_pop ();
+  gc_free (&gc);
+}
+
+void
+pre_select (struct context *c)
+{
+  /* make sure current time (now) is updated on function entry */
+
+  /*
+   * Start with an effectively infinite timeout, then let it
+   * reduce to a timeout that reflects the component which
+   * needs the earliest service.
+   */
+  c->c2.timeval.tv_sec = BIG_TIMEOUT;
+  c->c2.timeval.tv_usec = 0;
+
+#if defined(WIN32)
+  if (check_debug_level (D_TAP_WIN32_DEBUG))
+    {
+      c->c2.timeval.tv_sec = 1;
+      if (tuntap_defined (c->c1.tuntap))
+	tun_show_debug (c->c1.tuntap);
+    }
+#endif
+
+  /* check coarse timers? */
+  check_coarse_timers (c);
+  if (c->sig->signal_received)
+    return;
+
+  /* Does TLS need service? */
+  check_tls (c);
+
+  /* In certain cases, TLS errors will require a restart */
+  check_tls_errors (c);
+  if (c->sig->signal_received)
+    return;
+
+  /* check for incoming configuration info on the control channel */
+  check_incoming_control_channel (c);
+
+#ifdef ENABLE_OCC
+  /* Should we send an OCC message? */
+  check_send_occ_msg (c);
+#endif
+
+#ifdef ENABLE_FRAGMENT
+  /* Should we deliver a datagram fragment to remote? */
+  check_fragment (c);
+#endif
+
+  /* Update random component of timeout */
+  check_timeout_random_component (c);
+}
+
+/*
+ * Wait for I/O events.  Used for both TCP & UDP sockets
+ * in point-to-point mode and for UDP sockets in
+ * point-to-multipoint mode.
+ */
+
+void
+io_wait_dowork (struct context *c, const unsigned int flags)
+{
+  unsigned int socket = 0;
+  unsigned int tuntap = 0;
+  struct event_set_return esr[4];
+
+  /* These shifts all depend on EVENT_READ and EVENT_WRITE */
+  static const int socket_shift = 0;     /* depends on SOCKET_READ and SOCKET_WRITE */
+  static const int tun_shift = 2;        /* depends on TUN_READ and TUN_WRITE */
+  static const int err_shift = 4;        /* depends on ES_ERROR */
+#ifdef ENABLE_MANAGEMENT
+  static const int management_shift = 6; /* depends on MANAGEMENT_READ and MANAGEMENT_WRITE */
+#endif
+
+  /*
+   * Decide what kind of events we want to wait for.
+   */
+  event_reset (c->c2.event_set);
+
+  /*
+   * On win32 we use the keyboard or an event object as a source
+   * of asynchronous signals.
+   */
+  if (flags & IOW_WAIT_SIGNAL)
+    wait_signal (c->c2.event_set, (void*)&err_shift);
+
+  /*
+   * If outgoing data (for TCP/UDP port) pending, wait for ready-to-send
+   * status from TCP/UDP port. Otherwise, wait for incoming data on
+   * TUN/TAP device.
+   */
+  if (flags & IOW_TO_LINK)
+    {
+      if (flags & IOW_SHAPER)
+	{
+	  /*
+	   * If sending this packet would put us over our traffic shaping
+	   * quota, don't send -- instead compute the delay we must wait
+	   * until it will be OK to send the packet.
+	   */
+#ifdef HAVE_GETTIMEOFDAY
+	  int delay = 0;
+
+	  /* set traffic shaping delay in microseconds */
+	  if (c->options.shaper)
+	    delay = max_int (delay, shaper_delay (&c->c2.shaper));
+	  
+	  if (delay < 1000)
+	    {
+	      socket |= EVENT_WRITE;
+	    }
+	  else
+	    {
+	      shaper_soonest_event (&c->c2.timeval, delay);
+	    }
+#else /* HAVE_GETTIMEOFDAY */
+	  socket |= EVENT_WRITE;
+#endif /* HAVE_GETTIMEOFDAY */
+	}
+      else
+	{
+	  socket |= EVENT_WRITE;
+	}
+    }
+  else if (!((flags & IOW_FRAG) && TO_LINK_FRAG (c)))
+    {
+      if (flags & IOW_READ_TUN)
+	tuntap |= EVENT_READ;
+    }
+
+  /*
+   * If outgoing data (for TUN/TAP device) pending, wait for ready-to-send status
+   * from device.  Otherwise, wait for incoming data on TCP/UDP port.
+   */
+  if (flags & IOW_TO_TUN)
+    {
+      tuntap |= EVENT_WRITE;
+    }
+  else
+    {
+      if (flags & IOW_READ_LINK)
+	socket |= EVENT_READ;
+    }
+
+  /*
+   * outgoing bcast buffer waiting to be sent?
+   */
+  if (flags & IOW_MBUF)
+    socket |= EVENT_WRITE;
+
+  /*
+   * Force wait on TUN input, even if also waiting on TCP/UDP output
+   */
+  if (flags & IOW_READ_TUN_FORCE)
+    tuntap |= EVENT_READ;
+
+  /*
+   * Configure event wait based on socket, tuntap flags.
+   */
+  socket_set (c->c2.link_socket, c->c2.event_set, socket, (void*)&socket_shift, NULL);
+  tun_set (c->c1.tuntap, c->c2.event_set, tuntap, (void*)&tun_shift, NULL);
+
+#ifdef ENABLE_MANAGEMENT
+  if (management)
+    management_socket_set (management, c->c2.event_set, (void*)&management_shift, NULL);
+#endif
+
+  /*
+   * Possible scenarios:
+   *  (1) tcp/udp port has data available to read
+   *  (2) tcp/udp port is ready to accept more data to write
+   *  (3) tun dev has data available to read
+   *  (4) tun dev is ready to accept more data to write
+   *  (5) we received a signal (handler sets signal_received)
+   *  (6) timeout (tv) expired
+   */
+
+  c->c2.event_set_status = ES_ERROR;
+
+  if (!c->sig->signal_received)
+    {
+      if (!(flags & IOW_CHECK_RESIDUAL) || !socket_read_residual (c->c2.link_socket))
+	{
+	  int status;
+
+#ifdef ENABLE_DEBUG
+	  if (check_debug_level (D_EVENT_WAIT))
+	    show_wait_status (c);
+#endif
+
+	  /*
+	   * Wait for something to happen.
+	   */
+	  status = event_wait (c->c2.event_set, &c->c2.timeval, esr, SIZE(esr));
+
+	  check_status (status, "event_wait", NULL, NULL);
+
+	  if (status > 0)
+	    {
+	      int i;
+	      c->c2.event_set_status = 0;
+	      for (i = 0; i < status; ++i)
+		{
+		  const struct event_set_return *e = &esr[i];
+		  c->c2.event_set_status |= ((e->rwflags & 3) << *((int*)e->arg));
+		}
+	    }
+	  else if (status == 0)
+	    {
+	      c->c2.event_set_status = ES_TIMEOUT;
+	    }
+	}
+      else
+	{
+	  c->c2.event_set_status = SOCKET_READ;
+	}
+    }
+
+  /* 'now' should always be a reasonably up-to-date timestamp */
+  update_time ();
+
+  /* set signal_received if a signal was received */
+  if (c->c2.event_set_status & ES_ERROR)
+    get_signal (&c->sig->signal_received);
+
+  dmsg (D_EVENT_WAIT, "I/O WAIT status=0x%04x", c->c2.event_set_status);
+}
+
+void
+process_io (struct context *c)
+{
+  const unsigned int status = c->c2.event_set_status;
+
+#ifdef ENABLE_MANAGEMENT
+  if (status & (MANAGEMENT_READ|MANAGEMENT_WRITE))
+    {
+      ASSERT (management);
+      management_io (management);
+    }
+#endif
+
+  /* TCP/UDP port ready to accept write */
+  if (status & SOCKET_WRITE)
+    {
+      process_outgoing_link (c);
+    }
+  /* TUN device ready to accept write */
+  else if (status & TUN_WRITE)
+    {
+      process_outgoing_tun (c);
+    }
+  /* Incoming data on TCP/UDP port */
+  else if (status & SOCKET_READ)
+    {
+      read_incoming_link (c);
+      if (!IS_SIG (c))
+	process_incoming_link (c);
+    }
+  /* Incoming data on TUN device */
+  else if (status & TUN_READ)
+    {
+      read_incoming_tun (c);
+      if (!IS_SIG (c))
+	process_incoming_tun (c);
+    }
+}