Imported Upstream version 2.2.1upstream/2.2.1

1 files changed, 2808 insertions, 0 deletions

diff --git a/socket.c b/socket.c
new file mode 100644
index 0000000..4720398
--- /dev/null
+++ b/socket.c
@@ -0,0 +1,2808 @@
+/*
+ *  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
+ */
+
+#include "syshead.h"
+
+#include "socket.h"
+#include "fdmisc.h"
+#include "misc.h"
+#include "gremlin.h"
+#include "plugin.h"
+#include "ps.h"
+#include "manage.h"
+#include "misc.h"
+
+#include "memdbg.h"
+
+const int proto_overhead[] = { /* indexed by PROTO_x */
+  IPv4_UDP_HEADER_SIZE,
+  IPv4_TCP_HEADER_SIZE,
+  IPv4_TCP_HEADER_SIZE,
+  IPv4_TCP_HEADER_SIZE
+};
+
+/*
+ * Convert sockflags/getaddr_flags into getaddr_flags
+ */
+static unsigned int
+sf2gaf(const unsigned int getaddr_flags,
+       const unsigned int sockflags)
+{
+  if (sockflags & SF_HOST_RANDOMIZE)
+    return getaddr_flags | GETADDR_RANDOMIZE;
+  else
+    return getaddr_flags;
+}
+
+/*
+ * Functions related to the translation of DNS names to IP addresses.
+ */
+
+static const char*
+h_errno_msg(int h_errno_err)
+{
+  switch (h_errno_err)
+    {
+    case HOST_NOT_FOUND:
+      return "[HOST_NOT_FOUND] The specified host is unknown.";
+    case NO_DATA:
+      return "[NO_DATA] The requested name is valid but does not have an IP address.";
+    case NO_RECOVERY:
+      return "[NO_RECOVERY] A non-recoverable name server error occurred.";
+    case TRY_AGAIN:
+      return "[TRY_AGAIN] A temporary error occurred on an authoritative name server.";
+    }
+  return "[unknown h_errno value]";
+}
+
+/*
+ * Translate IP addr or hostname to in_addr_t.
+ * If resolve error, try again for
+ * resolve_retry_seconds seconds.
+ */
+in_addr_t
+getaddr (unsigned int flags,
+	 const char *hostname,
+	 int resolve_retry_seconds,
+	 bool *succeeded,
+	 volatile int *signal_received)
+{
+  return getaddr_multi (flags, hostname, resolve_retry_seconds, succeeded, signal_received, NULL);
+}
+
+in_addr_t
+getaddr_multi (unsigned int flags,
+	 const char *hostname,
+	 int resolve_retry_seconds,
+	 bool *succeeded,
+	 volatile int *signal_received,
+	 struct resolve_list *reslist)
+{
+  struct in_addr ia;
+  int status;
+  int sigrec = 0;
+  int msglevel = (flags & GETADDR_FATAL) ? M_FATAL : D_RESOLVE_ERRORS;
+  struct gc_arena gc = gc_new ();
+
+  if (reslist)
+    reslist->len = 0;
+
+  if (flags & GETADDR_RANDOMIZE)
+    hostname = hostname_randomize(hostname, &gc);
+
+  if (flags & GETADDR_MSG_VIRT_OUT)
+    msglevel |= M_MSG_VIRT_OUT;
+
+  CLEAR (ia);
+  if (succeeded)
+    *succeeded = false;
+
+  if ((flags & (GETADDR_FATAL_ON_SIGNAL|GETADDR_WARN_ON_SIGNAL))
+      && !signal_received)
+    signal_received = &sigrec;
+
+  status = openvpn_inet_aton (hostname, &ia); /* parse ascii IP address */
+
+  if (status != OIA_IP) /* parse as IP address failed? */
+    {
+      const int fail_wait_interval = 5; /* seconds */
+      int resolve_retries = (flags & GETADDR_TRY_ONCE) ? 1 : (resolve_retry_seconds / fail_wait_interval);
+      struct hostent *h;
+      const char *fmt;
+      int level = 0;
+
+      CLEAR (ia);
+
+      fmt = "RESOLVE: Cannot resolve host address: %s: %s";
+      if ((flags & GETADDR_MENTION_RESOLVE_RETRY)
+	  && !resolve_retry_seconds)
+	fmt = "RESOLVE: Cannot resolve host address: %s: %s (I would have retried this name query if you had specified the --resolv-retry option.)";
+
+      if (!(flags & GETADDR_RESOLVE) || status == OIA_ERROR)
+	{
+	  msg (msglevel, "RESOLVE: Cannot parse IP address: %s", hostname);
+	  goto done;
+	}
+
+#ifdef ENABLE_MANAGEMENT
+      if (flags & GETADDR_UPDATE_MANAGEMENT_STATE)
+	{
+	  if (management)
+	    management_set_state (management,
+				  OPENVPN_STATE_RESOLVE,
+				  NULL,
+				  (in_addr_t)0,
+				  (in_addr_t)0);
+	}
+#endif
+
+      /*
+       * Resolve hostname
+       */
+      while (true)
+	{
+	  /* try hostname lookup */
+#if defined(HAVE_RES_INIT)
+	  res_init ();
+#endif
+	  h = gethostbyname (hostname);
+
+	  if (signal_received)
+	    {
+	      get_signal (signal_received);
+	      if (*signal_received) /* were we interrupted by a signal? */
+		{
+		  h = NULL;
+		  if (*signal_received == SIGUSR1) /* ignore SIGUSR1 */
+		    {
+		      msg (level, "RESOLVE: Ignored SIGUSR1 signal received during DNS resolution attempt");
+		      *signal_received = 0;
+		    }
+		  else
+		    goto done;
+		}
+	    }
+
+	  /* success? */
+	  if (h)
+	    break;
+
+	  /* resolve lookup failed, should we
+	     continue or fail? */
+
+	  level = msglevel;
+	  if (resolve_retries > 0)
+	    level = D_RESOLVE_ERRORS;
+
+	  msg (level,
+	       fmt,
+	       hostname,
+	       h_errno_msg (h_errno));
+
+	  if (--resolve_retries <= 0)
+	    goto done;
+
+	  openvpn_sleep (fail_wait_interval);
+	}
+
+      if (h->h_addrtype != AF_INET || h->h_length != 4)
+	{
+	    msg (msglevel, "RESOLVE: Sorry, but we only accept IPv4 DNS names: %s", hostname);
+	    goto done;
+	}
+
+      ia.s_addr = *(in_addr_t *) (h->h_addr_list[0]);
+
+      if (ia.s_addr)
+	{
+	  if (h->h_addr_list[1]) /* more than one address returned */
+	    {
+	      int n = 0;
+
+	      /* count address list */
+	      while (h->h_addr_list[n])
+		++n;
+	      ASSERT (n >= 2);
+
+	      msg (D_RESOLVE_ERRORS, "RESOLVE: NOTE: %s resolves to %d addresses",
+		   hostname,
+		   n);
+
+	      /* choose address randomly, for basic load-balancing capability */
+	      /*ia.s_addr = *(in_addr_t *) (h->h_addr_list[get_random () % n]);*/
+
+	      /* choose first address */
+	      ia.s_addr = *(in_addr_t *) (h->h_addr_list[0]);
+
+	      if (reslist)
+		{
+		  int i;
+		  for (i = 0; i < n && i < SIZE(reslist->data); ++i)
+		    {
+		      in_addr_t a = *(in_addr_t *) (h->h_addr_list[i]);
+		      if (flags & GETADDR_HOST_ORDER)
+			a = ntohl(a);
+		      reslist->data[i] = a;
+		    }
+		  reslist->len = i;
+		}
+	    }
+	}
+
+      /* hostname resolve succeeded */
+      if (succeeded)
+	*succeeded = true;
+    }
+  else
+    {
+      /* IP address parse succeeded */
+      if (succeeded)
+	*succeeded = true;
+    }
+
+ done:
+  if (signal_received && *signal_received)
+    {
+      int level = 0;
+      if (flags & GETADDR_FATAL_ON_SIGNAL)
+	level = M_FATAL;
+      else if (flags & GETADDR_WARN_ON_SIGNAL)
+	level = M_WARN;
+      msg (level, "RESOLVE: signal received during DNS resolution attempt");
+    }
+
+  gc_free (&gc);
+  return (flags & GETADDR_HOST_ORDER) ? ntohl (ia.s_addr) : ia.s_addr;
+}
+
+/*
+ * We do our own inet_aton because the glibc function
+ * isn't very good about error checking.
+ */
+int
+openvpn_inet_aton (const char *dotted_quad, struct in_addr *addr)
+{
+  unsigned int a, b, c, d;
+
+  CLEAR (*addr);
+  if (sscanf (dotted_quad, "%u.%u.%u.%u", &a, &b, &c, &d) == 4)
+    {
+      if (a < 256 && b < 256 && c < 256 && d < 256)
+	{
+	  addr->s_addr = htonl (a<<24 | b<<16 | c<<8 | d);
+	  return OIA_IP; /* good dotted quad */
+	}
+    }
+  if (string_class (dotted_quad, CC_DIGIT|CC_DOT, 0))
+    return OIA_ERROR;    /* probably a badly formatted dotted quad */
+  else
+    return OIA_HOSTNAME; /* probably a hostname */
+}
+
+bool
+ip_addr_dotted_quad_safe (const char *dotted_quad)
+{
+  /* verify non-NULL */
+  if (!dotted_quad)
+    return false;
+
+  /* verify length is within limits */
+  if (strlen (dotted_quad) > 15)
+    return false;
+
+  /* verify that all chars are either numeric or '.' and that no numeric
+     substring is greater than 3 chars */
+  {
+    int nnum = 0;
+    const char *p = dotted_quad;
+    int c;
+
+    while ((c = *p++))
+      {
+	if (c >= '0' && c <= '9')
+	  {
+	    ++nnum;
+	    if (nnum > 3)
+	      return false;
+	  }
+	else if (c == '.')
+	  {
+	    nnum = 0;
+	  }
+	else
+	  return false;
+      }
+  }
+
+  /* verify that string will convert to IP address */
+  {
+    struct in_addr a;
+    return openvpn_inet_aton (dotted_quad, &a) == OIA_IP;
+  }
+}
+
+static bool
+dns_addr_safe (const char *addr)
+{
+  if (addr)
+    {
+      const size_t len = strlen (addr);
+      return len > 0 && len <= 255 && string_class (addr, CC_ALNUM|CC_DASH|CC_DOT, 0);
+    }
+  else
+    return false;
+}
+
+bool
+ip_or_dns_addr_safe (const char *addr, const bool allow_fqdn)
+{
+  if (ip_addr_dotted_quad_safe (addr))
+    return true;
+  else if (allow_fqdn)
+    return dns_addr_safe (addr);
+  else
+    return false;
+}
+
+bool
+mac_addr_safe (const char *mac_addr)
+{
+  /* verify non-NULL */
+  if (!mac_addr)
+    return false;
+
+  /* verify length is within limits */
+  if (strlen (mac_addr) > 17)
+    return false;
+
+  /* verify that all chars are either alphanumeric or ':' and that no
+     alphanumeric substring is greater than 2 chars */
+  {
+    int nnum = 0;
+    const char *p = mac_addr;
+    int c;
+
+    while ((c = *p++))
+      {
+	if ( (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c >= 'A' && c <= 'F') )
+	  {
+	    ++nnum;
+	    if (nnum > 2)
+	      return false;
+	  }
+	else if (c == ':')
+	  {
+	    nnum = 0;
+	  }
+	else
+	  return false;
+      }
+  }
+
+  /* error-checking is left to script invoked in lladdr.c */
+  return true;
+}
+
+static void
+update_remote (const char* host,
+	       struct openvpn_sockaddr *addr,
+	       bool *changed,
+	       const unsigned int sockflags)
+{
+  if (host && addr)
+    {
+      const in_addr_t new_addr = getaddr (
+					  sf2gaf(GETADDR_RESOLVE|GETADDR_UPDATE_MANAGEMENT_STATE, sockflags),
+					  host,
+					  1,
+					  NULL,
+					  NULL);
+      if (new_addr && addr->sa.sin_addr.s_addr != new_addr)
+	{
+	  addr->sa.sin_addr.s_addr = new_addr;
+	  *changed = true;
+	}
+    }
+}
+
+static int
+socket_get_sndbuf (int sd)
+{
+#if defined(HAVE_GETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_SNDBUF)
+  int val;
+  socklen_t len;
+
+  len = sizeof (val);
+  if (getsockopt (sd, SOL_SOCKET, SO_SNDBUF, (void *) &val, &len) == 0
+      && len == sizeof (val))
+    return val;
+#endif
+  return 0;
+}
+
+static void
+socket_set_sndbuf (int sd, int size)
+{
+#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_SNDBUF)
+  if (size > 0 && size < SOCKET_SND_RCV_BUF_MAX)
+    {
+      if (setsockopt (sd, SOL_SOCKET, SO_SNDBUF, (void *) &size, sizeof (size)) != 0)
+	{
+	  msg (M_WARN, "NOTE: setsockopt SO_SNDBUF=%d failed", size);
+	}
+    }
+#endif
+}
+
+static int
+socket_get_rcvbuf (int sd)
+{
+#if defined(HAVE_GETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_RCVBUF)
+  int val;
+  socklen_t len;
+
+  len = sizeof (val);
+  if (getsockopt (sd, SOL_SOCKET, SO_RCVBUF, (void *) &val, &len) == 0
+      && len == sizeof (val))
+    return val;
+#endif
+  return 0;
+}
+
+static bool
+socket_set_rcvbuf (int sd, int size)
+{
+#if defined(HAVE_SETSOCKOPT) && defined(SOL_SOCKET) && defined(SO_RCVBUF)
+  if (size > 0 && size < SOCKET_SND_RCV_BUF_MAX)
+    {
+      if (setsockopt (sd, SOL_SOCKET, SO_RCVBUF, (void *) &size, sizeof (size)) != 0)
+	{
+	  msg (M_WARN, "NOTE: setsockopt SO_RCVBUF=%d failed", size);
+	  return false;
+	}
+    }
+  return true;
+#endif
+}
+
+static void
+socket_set_buffers (int fd, const struct socket_buffer_size *sbs)
+{
+  if (sbs)
+    {
+      const int sndbuf_old = socket_get_sndbuf (fd);
+      const int rcvbuf_old = socket_get_rcvbuf (fd);
+
+      if (sbs->sndbuf)
+	socket_set_sndbuf (fd, sbs->sndbuf);
+
+      if (sbs->rcvbuf)
+	socket_set_rcvbuf (fd, sbs->rcvbuf);
+       
+      msg (D_OSBUF, "Socket Buffers: R=[%d->%d] S=[%d->%d]",
+	   rcvbuf_old,
+	   socket_get_rcvbuf (fd),
+	   sndbuf_old,
+	   socket_get_sndbuf (fd));
+    }
+}
+
+/*
+ * Set other socket options
+ */
+
+static bool
+socket_set_tcp_nodelay (int sd, int state)
+{
+#if defined(WIN32) || (defined(HAVE_SETSOCKOPT) && defined(IPPROTO_TCP) && defined(TCP_NODELAY))
+  if (setsockopt (sd, IPPROTO_TCP, TCP_NODELAY, (void *) &state, sizeof (state)) != 0)
+    {
+      msg (M_WARN, "NOTE: setsockopt TCP_NODELAY=%d failed", state);
+      return false;
+    }
+  else
+    {
+      dmsg (D_OSBUF, "Socket flags: TCP_NODELAY=%d succeeded", state);
+      return true;
+    }
+#else
+  msg (M_WARN, "NOTE: setsockopt TCP_NODELAY=%d failed (No kernel support)", state);
+  return false;
+#endif
+}
+
+static bool
+socket_set_flags (int sd, unsigned int sockflags)
+{
+  if (sockflags & SF_TCP_NODELAY)
+    return socket_set_tcp_nodelay (sd, 1);
+  else
+    return true;
+}
+
+bool
+link_socket_update_flags (struct link_socket *ls, unsigned int sockflags)
+{
+  if (ls && socket_defined (ls->sd))
+    return socket_set_flags (ls->sd, ls->sockflags = sockflags);
+  else
+    return false;
+}
+
+void
+link_socket_update_buffer_sizes (struct link_socket *ls, int rcvbuf, int sndbuf)
+{
+  if (ls && socket_defined (ls->sd))
+    {
+      ls->socket_buffer_sizes.sndbuf = sndbuf;
+      ls->socket_buffer_sizes.rcvbuf = rcvbuf;
+      socket_set_buffers (ls->sd, &ls->socket_buffer_sizes);
+    }
+}
+
+/*
+ * SOCKET INITALIZATION CODE.
+ * Create a TCP/UDP socket
+ */
+
+socket_descriptor_t
+create_socket_tcp (void)
+{
+  socket_descriptor_t sd;
+
+  if ((sd = socket (PF_INET, SOCK_STREAM, IPPROTO_TCP)) < 0)
+    msg (M_SOCKERR, "Cannot create TCP socket");
+
+#ifndef WIN32 /* using SO_REUSEADDR on Windows will cause bind to succeed on port conflicts! */
+  /* set SO_REUSEADDR on socket */
+  {
+    int on = 1;
+    if (setsockopt (sd, SOL_SOCKET, SO_REUSEADDR,
+		    (void *) &on, sizeof (on)) < 0)
+      msg (M_SOCKERR, "TCP: Cannot setsockopt SO_REUSEADDR on TCP socket");
+  }
+#endif
+
+#if 0
+  /* set socket linger options */
+  {
+    struct linger linger;
+    linger.l_onoff = 1;
+    linger.l_linger = 2;
+    if (setsockopt (sd, SOL_SOCKET, SO_LINGER,
+		    (void *) &linger, sizeof (linger)) < 0)
+      msg (M_SOCKERR, "TCP: Cannot setsockopt SO_LINGER on TCP socket");
+  }
+#endif
+
+  return sd;
+}
+
+static socket_descriptor_t
+create_socket_udp (const unsigned int flags)
+{
+  socket_descriptor_t sd;
+
+  if ((sd = socket (PF_INET, SOCK_DGRAM, IPPROTO_UDP)) < 0)
+    msg (M_SOCKERR, "UDP: Cannot create UDP socket");
+#if ENABLE_IP_PKTINFO
+  else if (flags & SF_USE_IP_PKTINFO)
+    {
+      int pad = 1;
+      setsockopt (sd, SOL_IP, IP_PKTINFO, (void*)&pad, sizeof(pad));
+    }
+#endif
+  return sd;
+}
+
+static void
+create_socket (struct link_socket *sock)
+{
+  /* create socket */
+  if (sock->info.proto == PROTO_UDPv4)
+    {
+      sock->sd = create_socket_udp (sock->sockflags);
+
+#ifdef ENABLE_SOCKS
+      if (sock->socks_proxy)
+	sock->ctrl_sd = create_socket_tcp ();
+#endif
+    }
+  else if (sock->info.proto == PROTO_TCPv4_SERVER
+	   || sock->info.proto == PROTO_TCPv4_CLIENT)
+    {
+      sock->sd = create_socket_tcp ();
+    }
+  else
+    {
+      ASSERT (0);
+    }
+}
+
+/*
+ * Functions used for establishing a TCP stream connection.
+ */
+
+static void
+socket_do_listen (socket_descriptor_t sd,
+		  const struct openvpn_sockaddr *local,
+		  bool do_listen,
+		  bool do_set_nonblock)
+{
+  struct gc_arena gc = gc_new ();
+  if (do_listen)
+    {
+      msg (M_INFO, "Listening for incoming TCP connection on %s", 
+	   print_sockaddr (local, &gc));
+      if (listen (sd, 1))
+	msg (M_SOCKERR, "TCP: listen() failed");
+    }
+
+  /* set socket to non-blocking mode */
+  if (do_set_nonblock)
+    set_nonblock (sd);
+
+  gc_free (&gc);
+}
+
+socket_descriptor_t
+socket_do_accept (socket_descriptor_t sd,
+		  struct link_socket_actual *act,
+		  const bool nowait)
+{
+  socklen_t remote_len = sizeof (act->dest.sa);
+  socket_descriptor_t new_sd = SOCKET_UNDEFINED;
+
+  CLEAR (*act);
+
+#ifdef HAVE_GETPEERNAME
+  if (nowait)
+    {
+      new_sd = getpeername (sd, (struct sockaddr *) &act->dest.sa, &remote_len);
+
+      if (!socket_defined (new_sd))
+	msg (D_LINK_ERRORS | M_ERRNO_SOCK, "TCP: getpeername() failed");
+      else
+	new_sd = sd;
+    }
+#else
+  if (nowait)
+    msg (M_WARN, "TCP: this OS does not provide the getpeername() function");
+#endif
+  else
+    {
+      new_sd = accept (sd, (struct sockaddr *) &act->dest.sa, &remote_len);
+    }
+
+#if 0 /* For debugging only, test the effect of accept() failures */
+ {
+   static int foo = 0;
+   ++foo;
+   if (foo & 1)
+     new_sd = -1;
+ }
+#endif
+
+  if (!socket_defined (new_sd))
+    {
+      msg (D_LINK_ERRORS | M_ERRNO_SOCK, "TCP: accept(%d) failed", sd);
+    }
+  else if (remote_len != sizeof (act->dest.sa))
+    {
+      msg (D_LINK_ERRORS, "TCP: Received strange incoming connection with unknown address length=%d", remote_len);
+      openvpn_close_socket (new_sd);
+      new_sd = SOCKET_UNDEFINED;
+    }
+  return new_sd;
+}
+
+static void
+tcp_connection_established (const struct link_socket_actual *act)
+{
+  struct gc_arena gc = gc_new ();
+  msg (M_INFO, "TCP connection established with %s", 
+       print_link_socket_actual (act, &gc));
+  gc_free (&gc);
+}
+
+static int
+socket_listen_accept (socket_descriptor_t sd,
+		      struct link_socket_actual *act,
+		      const char *remote_dynamic,
+		      bool *remote_changed,
+		      const struct openvpn_sockaddr *local,
+		      bool do_listen,
+		      bool nowait,
+		      volatile int *signal_received)
+{
+  struct gc_arena gc = gc_new ();
+  /* struct openvpn_sockaddr *remote = &act->dest; */
+  struct openvpn_sockaddr remote_verify = act->dest;
+  int new_sd = SOCKET_UNDEFINED;
+
+  CLEAR (*act);
+  socket_do_listen (sd, local, do_listen, true);
+
+  while (true)
+    {
+      int status;
+      fd_set reads;
+      struct timeval tv;
+
+      FD_ZERO (&reads);
+      FD_SET (sd, &reads);
+      tv.tv_sec = 0;
+      tv.tv_usec = 0;
+
+      status = select (sd + 1, &reads, NULL, NULL, &tv);
+
+      get_signal (signal_received);
+      if (*signal_received)
+	{
+	  gc_free (&gc);
+	  return sd;
+	}
+
+      if (status < 0)
+	msg (D_LINK_ERRORS | M_ERRNO_SOCK, "TCP: select() failed");
+
+      if (status <= 0)
+	{
+	  openvpn_sleep (1);
+	  continue;
+	}
+
+      new_sd = socket_do_accept (sd, act, nowait);
+
+      if (socket_defined (new_sd))
+	{
+	  update_remote (remote_dynamic, &remote_verify, remote_changed, 0);
+	  if (addr_defined (&remote_verify)
+	      && !addr_match (&remote_verify, &act->dest))
+	    {
+	      msg (M_WARN,
+		   "TCP NOTE: Rejected connection attempt from %s due to --remote setting",
+		   print_link_socket_actual (act, &gc));
+	      if (openvpn_close_socket (new_sd))
+		msg (M_SOCKERR, "TCP: close socket failed (new_sd)");
+	    }
+	  else
+	    break;
+	}
+      openvpn_sleep (1);
+    }
+
+  if (!nowait && openvpn_close_socket (sd))
+    msg (M_SOCKERR, "TCP: close socket failed (sd)");
+
+  tcp_connection_established (act);
+
+  gc_free (&gc);
+  return new_sd;
+}
+
+void
+socket_bind (socket_descriptor_t sd,
+             struct openvpn_sockaddr *local,
+	     const char *prefix)
+{
+  struct gc_arena gc = gc_new ();
+
+  if (bind (sd, (struct sockaddr *) &local->sa, sizeof (local->sa)))
+    {
+      const int errnum = openvpn_errno_socket ();
+      msg (M_FATAL, "%s: Socket bind failed on local address %s: %s",
+	   prefix,
+           print_sockaddr (local, &gc),
+           strerror_ts (errnum, &gc));
+    }
+  gc_free (&gc);
+}
+
+int
+openvpn_connect (socket_descriptor_t sd,
+		 struct openvpn_sockaddr *remote,
+		 int connect_timeout,
+		 volatile int *signal_received)
+{
+  int status = 0;
+
+#ifdef CONNECT_NONBLOCK
+  set_nonblock (sd);
+  status = connect (sd, (struct sockaddr *) &remote->sa, sizeof (remote->sa));
+  if (status)
+    status = openvpn_errno_socket ();
+  if (status == EINPROGRESS)
+    {
+      while (true)
+	{
+	  fd_set writes;
+	  struct timeval tv;
+
+	  FD_ZERO (&writes);
+	  FD_SET (sd, &writes);
+	  tv.tv_sec = 0;
+	  tv.tv_usec = 0;
+
+	  status = select (sd + 1, NULL, &writes, NULL, &tv);
+
+	  if (signal_received)
+	    {
+	      get_signal (signal_received);
+	      if (*signal_received)
+		{
+		  status = 0;
+		  break;
+		}
+	    }
+	  if (status < 0)
+	    {
+	      status = openvpn_errno_socket ();
+	      break;
+	    }
+	  if (status <= 0)
+	    {
+	      if (--connect_timeout < 0)
+		{
+		  status = ETIMEDOUT;
+		  break;
+		}
+	      openvpn_sleep (1);
+	      continue;
+	    }
+
+	  /* got it */
+	  {
+	    int val = 0;
+	    socklen_t len;
+
+	    len = sizeof (val);
+	    if (getsockopt (sd, SOL_SOCKET, SO_ERROR, (void *) &val, &len) == 0
+		&& len == sizeof (val))
+	      status = val;
+	    else
+	      status = openvpn_errno_socket ();
+	    break;
+	  }
+	}
+    }
+#else
+  status = connect (sd, (struct sockaddr *) &remote->sa, sizeof (remote->sa));
+  if (status)
+    status = openvpn_errno_socket ();
+#endif
+
+  return status;
+}
+
+void
+socket_connect (socket_descriptor_t *sd,
+                struct openvpn_sockaddr *local,
+                bool bind_local,
+		struct openvpn_sockaddr *remote,
+		const bool connection_profiles_defined,
+		const char *remote_dynamic,
+		bool *remote_changed,
+		const int connect_retry_seconds,
+		const int connect_timeout,
+		const int connect_retry_max,
+		const unsigned int sockflags,
+		volatile int *signal_received)
+{
+  struct gc_arena gc = gc_new ();
+  int retry = 0;
+
+#ifdef CONNECT_NONBLOCK
+  msg (M_INFO, "Attempting to establish TCP connection with %s [nonblock]", 
+       print_sockaddr (remote, &gc));
+#else
+  msg (M_INFO, "Attempting to establish TCP connection with %s", 
+       print_sockaddr (remote, &gc));
+#endif
+
+  while (true)
+    {
+      int status;
+
+#ifdef ENABLE_MANAGEMENT
+      if (management)
+	management_set_state (management,
+			      OPENVPN_STATE_TCP_CONNECT,
+			      NULL,
+			      (in_addr_t)0,
+			      (in_addr_t)0);
+#endif
+
+      status = openvpn_connect (*sd, remote, connect_timeout, signal_received);
+
+      get_signal (signal_received);
+      if (*signal_received)
+	goto done;
+
+      if (!status)
+	break;
+
+      msg (D_LINK_ERRORS,
+	   "TCP: connect to %s failed, will try again in %d seconds: %s",
+	   print_sockaddr (remote, &gc),
+	   connect_retry_seconds,
+	   strerror_ts (status, &gc));
+
+      gc_reset (&gc);
+
+      openvpn_close_socket (*sd);
+      *sd = SOCKET_UNDEFINED;
+
+      if ((connect_retry_max > 0 && ++retry >= connect_retry_max) || connection_profiles_defined)
+	{
+	  *signal_received = SIGUSR1;
+	  goto done;
+	}
+
+      openvpn_sleep (connect_retry_seconds);
+
+      get_signal (signal_received);
+      if (*signal_received)
+	goto done;
+
+      *sd = create_socket_tcp ();
+      if (bind_local)
+        socket_bind (*sd, local, "TCP Client");
+      update_remote (remote_dynamic, remote, remote_changed, sockflags);
+    }
+
+  msg (M_INFO, "TCP connection established with %s", 
+       print_sockaddr (remote, &gc));
+
+ done:
+  gc_free (&gc);
+}
+
+/* For stream protocols, allocate a buffer to build up packet.
+   Called after frame has been finalized. */
+
+static void
+socket_frame_init (const struct frame *frame, struct link_socket *sock)
+{
+#ifdef WIN32
+  overlapped_io_init (&sock->reads, frame, FALSE, false);
+  overlapped_io_init (&sock->writes, frame, TRUE, false);
+  sock->rw_handle.read = sock->reads.overlapped.hEvent;
+  sock->rw_handle.write = sock->writes.overlapped.hEvent;
+#endif
+
+  if (link_socket_connection_oriented (sock))
+    {
+#ifdef WIN32
+      stream_buf_init (&sock->stream_buf,
+		       &sock->reads.buf_init,
+		       sock->sockflags,
+		       sock->info.proto);
+#else
+      alloc_buf_sock_tun (&sock->stream_buf_data,
+			  frame,
+			  false,
+			  FRAME_HEADROOM_MARKER_READ_STREAM);
+
+      stream_buf_init (&sock->stream_buf,
+		       &sock->stream_buf_data,
+		       sock->sockflags,
+		       sock->info.proto);
+#endif
+    }
+}
+
+/*
+ * Adjust frame structure based on a Path MTU value given
+ * to us by the OS.
+ */
+void
+frame_adjust_path_mtu (struct frame *frame, int pmtu, int proto)
+{
+  frame_set_mtu_dynamic (frame, pmtu - datagram_overhead (proto), SET_MTU_UPPER_BOUND);
+}
+
+static void
+resolve_bind_local (struct link_socket *sock)
+{
+  struct gc_arena gc = gc_new ();
+
+  /* resolve local address if undefined */
+  if (!addr_defined (&sock->info.lsa->local))
+    {
+      sock->info.lsa->local.sa.sin_family = AF_INET;
+      sock->info.lsa->local.sa.sin_addr.s_addr =
+	(sock->local_host ? getaddr (GETADDR_RESOLVE | GETADDR_WARN_ON_SIGNAL | GETADDR_FATAL,
+				     sock->local_host,
+				     0,
+				     NULL,
+				     NULL)
+	 : htonl (INADDR_ANY));
+      sock->info.lsa->local.sa.sin_port = htons (sock->local_port);
+    }
+  
+  /* bind to local address/port */
+  if (sock->bind_local)
+    {
+#ifdef ENABLE_SOCKS
+      if (sock->socks_proxy && sock->info.proto == PROTO_UDPv4)
+          socket_bind (sock->ctrl_sd, &sock->info.lsa->local, "SOCKS");
+      else
+#endif
+          socket_bind (sock->sd, &sock->info.lsa->local, "TCP/UDP");
+    }
+  gc_free (&gc);
+}
+
+static void
+resolve_remote (struct link_socket *sock,
+		int phase,
+		const char **remote_dynamic,
+		volatile int *signal_received)
+{
+  struct gc_arena gc = gc_new ();
+
+  if (!sock->did_resolve_remote)
+    {
+      /* resolve remote address if undefined */
+      if (!addr_defined (&sock->info.lsa->remote))
+	{
+	  sock->info.lsa->remote.sa.sin_family = AF_INET;
+	  sock->info.lsa->remote.sa.sin_addr.s_addr = 0;
+
+	  if (sock->remote_host)
+	    {
+	      unsigned int flags = sf2gaf(GETADDR_RESOLVE|GETADDR_UPDATE_MANAGEMENT_STATE, sock->sockflags);
+	      int retry = 0;
+	      bool status = false;
+
+	      if (sock->connection_profiles_defined && sock->resolve_retry_seconds == RESOLV_RETRY_INFINITE)
+		{
+		  if (phase == 2)
+		    flags |= (GETADDR_TRY_ONCE | GETADDR_FATAL);
+		  retry = 0;
+		}
+	      else if (phase == 1)
+		{
+		  if (sock->resolve_retry_seconds)
+		    {
+		      retry = 0;
+		    }
+		  else
+		    {
+		      flags |= (GETADDR_FATAL | GETADDR_MENTION_RESOLVE_RETRY);
+		      retry = 0;
+		    }
+		}
+	      else if (phase == 2)
+		{
+		  if (sock->resolve_retry_seconds)
+		    {
+		      flags |= GETADDR_FATAL;
+		      retry = sock->resolve_retry_seconds;
+		    }
+		  else
+		    {
+		      ASSERT (0);
+		    }
+		}
+	      else
+		{
+		  ASSERT (0);
+		}
+
+	      sock->info.lsa->remote.sa.sin_addr.s_addr = getaddr (
+		    flags,
+		    sock->remote_host,
+		    retry,
+		    &status,
+		    signal_received);
+	      
+	      dmsg (D_SOCKET_DEBUG, "RESOLVE_REMOTE flags=0x%04x phase=%d rrs=%d sig=%d status=%d",
+		   flags,
+		   phase,
+		   retry,
+		   signal_received ? *signal_received : -1,
+		   status);
+
+	      if (signal_received)
+		{
+		  if (*signal_received)
+		    goto done;
+		}
+	      if (!status)
+		{
+		  if (signal_received)
+		    *signal_received = SIGUSR1;
+		  goto done;
+		}
+	    }
+
+	  sock->info.lsa->remote.sa.sin_port = htons (sock->remote_port);
+	}
+  
+      /* should we re-use previous active remote address? */
+      if (link_socket_actual_defined (&sock->info.lsa->actual))
+	{
+	  msg (M_INFO, "TCP/UDP: Preserving recently used remote address: %s",
+	       print_link_socket_actual (&sock->info.lsa->actual, &gc));
+	  if (remote_dynamic)
+	    *remote_dynamic = NULL;
+	}
+      else
+	{
+	  CLEAR (sock->info.lsa->actual);
+	  sock->info.lsa->actual.dest = sock->info.lsa->remote;
+	}
+
+      /* remember that we finished */
+      sock->did_resolve_remote = true;
+    }
+
+ done:
+  gc_free (&gc);
+}
+
+struct link_socket *
+link_socket_new (void)
+{
+  struct link_socket *sock;
+
+  ALLOC_OBJ_CLEAR (sock, struct link_socket);
+  sock->sd = SOCKET_UNDEFINED;
+#ifdef ENABLE_SOCKS
+  sock->ctrl_sd = SOCKET_UNDEFINED;
+#endif
+  return sock;
+}
+
+/* bind socket if necessary */
+void
+link_socket_init_phase1 (struct link_socket *sock,
+			 const bool connection_profiles_defined,
+			 const char *local_host,
+			 int local_port,
+			 const char *remote_host,
+			 int remote_port,
+			 int proto,
+			 int mode,
+			 const struct link_socket *accept_from,
+#ifdef ENABLE_HTTP_PROXY
+			 struct http_proxy_info *http_proxy,
+#endif
+#ifdef ENABLE_SOCKS
+			 struct socks_proxy_info *socks_proxy,
+#endif
+#ifdef ENABLE_DEBUG
+			 int gremlin,
+#endif
+			 bool bind_local,
+			 bool remote_float,
+			 int inetd,
+			 struct link_socket_addr *lsa,
+			 const char *ipchange_command,
+			 const struct plugin_list *plugins,
+			 int resolve_retry_seconds,
+			 int connect_retry_seconds,
+			 int connect_timeout,
+			 int connect_retry_max,
+			 int mtu_discover_type,
+			 int rcvbuf,
+			 int sndbuf,
+			 unsigned int sockflags)
+{
+  ASSERT (sock);
+
+  sock->connection_profiles_defined = connection_profiles_defined;
+
+  sock->local_host = local_host;
+  sock->local_port = local_port;
+  sock->remote_host = remote_host;
+  sock->remote_port = remote_port;
+
+#ifdef ENABLE_HTTP_PROXY
+  sock->http_proxy = http_proxy;
+#endif
+
+#ifdef ENABLE_SOCKS
+  sock->socks_proxy = socks_proxy;
+#endif
+
+  sock->bind_local = bind_local;
+  sock->inetd = inetd;
+  sock->resolve_retry_seconds = resolve_retry_seconds;
+  sock->connect_retry_seconds = connect_retry_seconds;
+  sock->connect_timeout = connect_timeout;
+  sock->connect_retry_max = connect_retry_max;
+  sock->mtu_discover_type = mtu_discover_type;
+
+#ifdef ENABLE_DEBUG
+  sock->gremlin = gremlin;
+#endif
+
+  sock->socket_buffer_sizes.rcvbuf = rcvbuf;
+  sock->socket_buffer_sizes.sndbuf = sndbuf;
+
+  sock->sockflags = sockflags;
+
+  sock->info.proto = proto;
+  sock->info.remote_float = remote_float;
+  sock->info.lsa = lsa;
+  sock->info.ipchange_command = ipchange_command;
+  sock->info.plugins = plugins;
+
+  sock->mode = mode;
+  if (mode == LS_MODE_TCP_ACCEPT_FROM)
+    {
+      ASSERT (accept_from);
+      ASSERT (sock->info.proto == PROTO_TCPv4_SERVER);
+      ASSERT (!sock->inetd);
+      sock->sd = accept_from->sd;
+    }
+
+  if (false)
+    ;
+#ifdef ENABLE_HTTP_PROXY
+  /* are we running in HTTP proxy mode? */
+  else if (sock->http_proxy)
+    {
+      ASSERT (sock->info.proto == PROTO_TCPv4_CLIENT);
+      ASSERT (!sock->inetd);
+
+      /* the proxy server */
+      sock->remote_host = http_proxy->options.server;
+      sock->remote_port = http_proxy->options.port;
+
+      /* the OpenVPN server we will use the proxy to connect to */
+      sock->proxy_dest_host = remote_host;
+      sock->proxy_dest_port = remote_port;
+    }
+#endif
+#ifdef ENABLE_SOCKS
+  /* or in Socks proxy mode? */
+  else if (sock->socks_proxy)
+    {
+      ASSERT (sock->info.proto == PROTO_TCPv4_CLIENT || sock->info.proto == PROTO_UDPv4);
+      ASSERT (!sock->inetd);
+
+      /* the proxy server */
+      sock->remote_host = socks_proxy->server;
+      sock->remote_port = socks_proxy->port;
+
+      /* the OpenVPN server we will use the proxy to connect to */
+      sock->proxy_dest_host = remote_host;
+      sock->proxy_dest_port = remote_port;
+    }
+#endif
+  else
+    {
+      sock->remote_host = remote_host;
+      sock->remote_port = remote_port;
+    }
+
+  /* bind behavior for TCP server vs. client */
+  if (sock->info.proto == PROTO_TCPv4_SERVER)
+    {
+      if (sock->mode == LS_MODE_TCP_ACCEPT_FROM)
+	sock->bind_local = false;
+      else
+	sock->bind_local = true;
+    }
+
+  /* were we started by inetd or xinetd? */
+  if (sock->inetd)
+    {
+      ASSERT (sock->info.proto != PROTO_TCPv4_CLIENT);
+      ASSERT (socket_defined (inetd_socket_descriptor));
+      sock->sd = inetd_socket_descriptor;
+    }
+  else if (mode != LS_MODE_TCP_ACCEPT_FROM)
+    {
+      create_socket (sock);
+
+      /* set socket buffers based on --sndbuf and --rcvbuf options */
+      socket_set_buffers (sock->sd, &sock->socket_buffer_sizes);
+
+      resolve_bind_local (sock);
+      resolve_remote (sock, 1, NULL, NULL);
+    }
+}
+
+/* finalize socket initialization */
+void
+link_socket_init_phase2 (struct link_socket *sock,
+			 const struct frame *frame,
+			 volatile int *signal_received)
+{
+  struct gc_arena gc = gc_new ();
+  const char *remote_dynamic = NULL;
+  bool remote_changed = false;
+  int sig_save = 0;
+
+  ASSERT (sock);
+
+  if (signal_received && *signal_received)
+    {
+      sig_save = *signal_received;
+      *signal_received = 0;
+    }
+
+  /* initialize buffers */
+  socket_frame_init (frame, sock);
+
+  /*
+   * Pass a remote name to connect/accept so that
+   * they can test for dynamic IP address changes
+   * and throw a SIGUSR1 if appropriate.
+   */
+  if (sock->resolve_retry_seconds)
+    remote_dynamic = sock->remote_host;
+
+  /* were we started by inetd or xinetd? */
+  if (sock->inetd)
+    {
+      if (sock->info.proto == PROTO_TCPv4_SERVER)
+	sock->sd =
+	  socket_listen_accept (sock->sd,
+				&sock->info.lsa->actual,
+				remote_dynamic,
+				&remote_changed,
+				&sock->info.lsa->local,
+				false,
+				sock->inetd == INETD_NOWAIT,
+				signal_received);
+      ASSERT (!remote_changed);
+      if (*signal_received)
+	goto done;
+    }
+  else
+    {
+      resolve_remote (sock, 2, &remote_dynamic, signal_received);
+
+      if (*signal_received)
+	goto done;
+
+      /* TCP client/server */
+      if (sock->info.proto == PROTO_TCPv4_SERVER)
+	{
+	  switch (sock->mode)
+	    {
+	    case LS_MODE_DEFAULT:
+	      sock->sd = socket_listen_accept (sock->sd,
+					       &sock->info.lsa->actual,
+					       remote_dynamic,
+					       &remote_changed,
+					       &sock->info.lsa->local,
+					       true,
+					       false,
+					       signal_received);
+	      break;
+	    case LS_MODE_TCP_LISTEN:
+	      socket_do_listen (sock->sd,
+				&sock->info.lsa->local,
+				true,
+				false);
+	      break;
+	    case LS_MODE_TCP_ACCEPT_FROM:
+	      sock->sd = socket_do_accept (sock->sd,
+					   &sock->info.lsa->actual,
+					   false);
+	      if (!socket_defined (sock->sd))
+		{
+		  *signal_received = SIGTERM;
+		  goto done;
+		}
+	      tcp_connection_established (&sock->info.lsa->actual);
+	      break;
+	    default:
+	      ASSERT (0);
+	    }
+	}
+      else if (sock->info.proto == PROTO_TCPv4_CLIENT)
+	{
+
+#ifdef GENERAL_PROXY_SUPPORT
+	  bool proxy_retry = false;
+#else
+	  const bool proxy_retry = false;
+#endif
+	  do {
+	    socket_connect (&sock->sd,
+			    &sock->info.lsa->local,
+			    sock->bind_local,
+			    &sock->info.lsa->actual.dest,
+			    sock->connection_profiles_defined,
+			    remote_dynamic,
+			    &remote_changed,
+			    sock->connect_retry_seconds,
+			    sock->connect_timeout,
+			    sock->connect_retry_max,
+			    sock->sockflags,
+			    signal_received);
+
+	    if (*signal_received)
+	      goto done;
+
+	    if (false)
+	      ;
+#ifdef ENABLE_HTTP_PROXY
+	    else if (sock->http_proxy)
+	      {
+		proxy_retry = establish_http_proxy_passthru (sock->http_proxy,
+							     sock->sd,
+							     sock->proxy_dest_host,
+							     sock->proxy_dest_port,
+							     &sock->stream_buf.residual,
+							     signal_received);
+	      }
+#endif
+#ifdef ENABLE_SOCKS
+	    else if (sock->socks_proxy)
+	      {
+		establish_socks_proxy_passthru (sock->socks_proxy,
+						sock->sd,
+						sock->proxy_dest_host,
+						sock->proxy_dest_port,
+						signal_received);
+	      }
+#endif
+	    if (proxy_retry)
+	      {
+		openvpn_close_socket (sock->sd);
+		sock->sd = create_socket_tcp ();
+	      }
+	  } while (proxy_retry);
+	}
+#ifdef ENABLE_SOCKS
+      else if (sock->info.proto == PROTO_UDPv4 && sock->socks_proxy)
+	{
+	  socket_connect (&sock->ctrl_sd,
+                          &sock->info.lsa->local,
+                          sock->bind_local,
+			  &sock->info.lsa->actual.dest,
+			  sock->connection_profiles_defined,
+			  remote_dynamic,
+			  &remote_changed,
+			  sock->connect_retry_seconds,
+			  sock->connect_timeout,
+			  sock->connect_retry_max,
+			  sock->sockflags,
+			  signal_received);
+
+	  if (*signal_received)
+	    goto done;
+
+	  establish_socks_proxy_udpassoc (sock->socks_proxy,
+					  sock->ctrl_sd,
+					  sock->sd,
+					  &sock->socks_relay.dest,
+					  signal_received);
+
+	  if (*signal_received)
+	    goto done;
+
+	  sock->remote_host = sock->proxy_dest_host;
+	  sock->remote_port = sock->proxy_dest_port;
+	  sock->did_resolve_remote = false;
+
+	  sock->info.lsa->actual.dest.sa.sin_addr.s_addr = 0;
+	  sock->info.lsa->remote.sa.sin_addr.s_addr = 0;
+
+	  resolve_remote (sock, 1, NULL, signal_received);
+
+	  if (*signal_received)
+	    goto done;
+	}
+#endif
+
+      if (*signal_received)
+	goto done;
+
+      if (remote_changed)
+	{
+	  msg (M_INFO, "TCP/UDP: Dynamic remote address changed during TCP connection establishment");
+	  sock->info.lsa->remote.sa.sin_addr.s_addr = sock->info.lsa->actual.dest.sa.sin_addr.s_addr;
+	}
+    }
+
+  /* set misc socket parameters */
+  socket_set_flags (sock->sd, sock->sockflags);
+
+  /* set socket to non-blocking mode */
+  set_nonblock (sock->sd);
+
+  /* set socket file descriptor to not pass across execs, so that
+     scripts don't have access to it */
+  set_cloexec (sock->sd);
+
+#ifdef ENABLE_SOCKS
+  if (socket_defined (sock->ctrl_sd))
+    set_cloexec (sock->ctrl_sd);
+#endif
+
+  /* set Path MTU discovery options on the socket */
+  set_mtu_discover_type (sock->sd, sock->mtu_discover_type);
+
+#if EXTENDED_SOCKET_ERROR_CAPABILITY
+  /* if the OS supports it, enable extended error passing on the socket */
+  set_sock_extended_error_passing (sock->sd);
+#endif
+
+  /* print local address */
+  if (sock->inetd)
+    msg (M_INFO, "%s link local: [inetd]", proto2ascii (sock->info.proto, true));
+  else
+    msg (M_INFO, "%s link local%s: %s",
+	 proto2ascii (sock->info.proto, true),
+	 (sock->bind_local ? " (bound)" : ""),
+	 print_sockaddr_ex (&sock->info.lsa->local, ":", sock->bind_local ? PS_SHOW_PORT : 0, &gc));
+
+  /* print active remote address */
+  msg (M_INFO, "%s link remote: %s",
+       proto2ascii (sock->info.proto, true),
+       print_link_socket_actual_ex (&sock->info.lsa->actual,
+				    ":",
+				    PS_SHOW_PORT_IF_DEFINED,
+				    &gc));
+
+ done:
+  if (sig_save && signal_received)
+    {
+      if (!*signal_received)
+	*signal_received = sig_save;
+    }
+  gc_free (&gc);
+}
+
+void
+link_socket_close (struct link_socket *sock)
+{
+  if (sock)
+    {
+#ifdef ENABLE_DEBUG
+      const int gremlin = GREMLIN_CONNECTION_FLOOD_LEVEL (sock->gremlin);
+#else
+      const int gremlin = 0;
+#endif
+
+      if (socket_defined (sock->sd))
+	{
+#ifdef WIN32
+	  close_net_event_win32 (&sock->listen_handle, sock->sd, 0);
+#endif
+	  if (!gremlin)
+	    {
+	      msg (D_CLOSE, "TCP/UDP: Closing socket");
+	      if (openvpn_close_socket (sock->sd))
+		msg (M_WARN | M_ERRNO_SOCK, "TCP/UDP: Close Socket failed");
+	    }
+	  sock->sd = SOCKET_UNDEFINED;
+#ifdef WIN32
+	  if (!gremlin)
+	    {
+	      overlapped_io_close (&sock->reads);
+	      overlapped_io_close (&sock->writes);
+	    }
+#endif
+	}
+
+#ifdef ENABLE_SOCKS
+      if (socket_defined (sock->ctrl_sd))
+	{
+	  if (openvpn_close_socket (sock->ctrl_sd))
+	    msg (M_WARN | M_ERRNO_SOCK, "TCP/UDP: Close Socket (ctrl_sd) failed");
+	  sock->ctrl_sd = SOCKET_UNDEFINED;
+	}
+#endif
+
+      stream_buf_close (&sock->stream_buf);
+      free_buf (&sock->stream_buf_data);
+      if (!gremlin)
+	free (sock);
+    }
+}
+
+/* for stream protocols, allow for packet length prefix */
+void
+socket_adjust_frame_parameters (struct frame *frame, int proto)
+{
+  if (link_socket_proto_connection_oriented (proto))
+    frame_add_to_extra_frame (frame, sizeof (packet_size_type));
+}
+
+void
+setenv_trusted (struct env_set *es, const struct link_socket_info *info)
+{
+  setenv_link_socket_actual (es, "trusted", &info->lsa->actual, SA_IP_PORT);
+}
+
+static void
+ipchange_fmt (const bool include_cmd, struct argv *argv, const struct link_socket_info *info, struct gc_arena *gc)
+{
+  const char *ip = print_sockaddr_ex (&info->lsa->actual.dest, NULL, 0, gc);
+  const char *port = print_sockaddr_ex (&info->lsa->actual.dest, NULL, PS_DONT_SHOW_ADDR|PS_SHOW_PORT, gc);
+  if (include_cmd)
+    argv_printf (argv, "%sc %s %s",
+		 info->ipchange_command,
+		 ip,
+		 port);
+  else
+    argv_printf (argv, "%s %s",
+		 ip,
+		 port);
+}
+
+void
+link_socket_connection_initiated (const struct buffer *buf,
+				  struct link_socket_info *info,
+				  const struct link_socket_actual *act,
+				  const char *common_name,
+				  struct env_set *es)
+{
+  struct gc_arena gc = gc_new ();
+  
+  info->lsa->actual = *act; /* Note: skip this line for --force-dest */
+  setenv_trusted (es, info);
+  info->connection_established = true;
+
+  /* Print connection initiated message, with common name if available */
+  {
+    struct buffer out = alloc_buf_gc (256, &gc);
+    if (common_name)
+      buf_printf (&out, "[%s] ", common_name);
+    buf_printf (&out, "Peer Connection Initiated with %s", print_link_socket_actual (&info->lsa->actual, &gc));
+    msg (M_INFO, "%s", BSTR (&out));
+  }
+
+  /* set environmental vars */
+  setenv_str (es, "common_name", common_name);
+
+  /* Process --ipchange plugin */
+  if (plugin_defined (info->plugins, OPENVPN_PLUGIN_IPCHANGE))
+    {
+      struct argv argv = argv_new ();
+      ipchange_fmt (false, &argv, info, &gc);
+      if (plugin_call (info->plugins, OPENVPN_PLUGIN_IPCHANGE, &argv, NULL, es) != OPENVPN_PLUGIN_FUNC_SUCCESS)
+	msg (M_WARN, "WARNING: ipchange plugin call failed");
+      argv_reset (&argv);
+    }
+
+  /* Process --ipchange option */
+  if (info->ipchange_command)
+    {
+      struct argv argv = argv_new ();
+      setenv_str (es, "script_type", "ipchange");
+      ipchange_fmt (true, &argv, info, &gc);
+      openvpn_run_script (&argv, es, 0, "--ipchange");
+      argv_reset (&argv);
+    }
+
+  gc_free (&gc);
+}
+
+void
+link_socket_bad_incoming_addr (struct buffer *buf,
+			       const struct link_socket_info *info,
+			       const struct link_socket_actual *from_addr)
+{
+  struct gc_arena gc = gc_new ();
+
+  msg (D_LINK_ERRORS,
+       "TCP/UDP: Incoming packet rejected from %s[%d], expected peer address: %s (allow this incoming source address/port by removing --remote or adding --float)",
+       print_link_socket_actual (from_addr, &gc),
+       (int)from_addr->dest.sa.sin_family,
+       print_sockaddr (&info->lsa->remote, &gc));
+  buf->len = 0;
+
+  gc_free (&gc);
+}
+
+void
+link_socket_bad_outgoing_addr (void)
+{
+  dmsg (D_READ_WRITE, "TCP/UDP: No outgoing address to send packet");
+}
+
+in_addr_t
+link_socket_current_remote (const struct link_socket_info *info)
+{
+  const struct link_socket_addr *lsa = info->lsa;
+
+  if (link_socket_actual_defined (&lsa->actual))
+    return ntohl (lsa->actual.dest.sa.sin_addr.s_addr);
+  else if (addr_defined (&lsa->remote))
+    return ntohl (lsa->remote.sa.sin_addr.s_addr);
+  else
+    return 0;
+}
+
+/*
+ * Return a status string describing socket state.
+ */
+const char *
+socket_stat (const struct link_socket *s, unsigned int rwflags, struct gc_arena *gc)
+{
+  struct buffer out = alloc_buf_gc (64, gc);
+  if (s)
+    {
+      if (rwflags & EVENT_READ)
+	{
+	  buf_printf (&out, "S%s",
+		      (s->rwflags_debug & EVENT_READ) ? "R" : "r");
+#ifdef WIN32
+	  buf_printf (&out, "%s",
+		      overlapped_io_state_ascii (&s->reads));
+#endif
+	}
+      if (rwflags & EVENT_WRITE)
+	{
+	  buf_printf (&out, "S%s",
+		      (s->rwflags_debug & EVENT_WRITE) ? "W" : "w");
+#ifdef WIN32
+	  buf_printf (&out, "%s",
+		      overlapped_io_state_ascii (&s->writes));
+#endif
+	}
+    }
+  else
+    {
+      buf_printf (&out, "S?");
+    }
+  return BSTR (&out);
+}
+
+/*
+ * Stream buffer functions, used to packetize a TCP
+ * stream connection.
+ */
+
+static inline void
+stream_buf_reset (struct stream_buf *sb)
+{
+  dmsg (D_STREAM_DEBUG, "STREAM: RESET");
+  sb->residual_fully_formed = false;
+  sb->buf = sb->buf_init;
+  buf_reset (&sb->next);
+  sb->len = -1;
+}
+
+void
+stream_buf_init (struct stream_buf *sb,
+		 struct buffer *buf,
+		 const unsigned int sockflags,
+		 const int proto)
+{
+  sb->buf_init = *buf;
+  sb->maxlen = sb->buf_init.len;
+  sb->buf_init.len = 0;
+  sb->residual = alloc_buf (sb->maxlen);
+  sb->error = false;
+#if PORT_SHARE
+  sb->port_share_state = ((sockflags & SF_PORT_SHARE) && (proto == PROTO_TCPv4_SERVER))
+    ? PS_ENABLED
+    : PS_DISABLED;
+#endif
+  stream_buf_reset (sb);
+
+  dmsg (D_STREAM_DEBUG, "STREAM: INIT maxlen=%d", sb->maxlen);
+}
+
+static inline void
+stream_buf_set_next (struct stream_buf *sb)
+{
+  /* set up 'next' for next i/o read */
+  sb->next = sb->buf;
+  sb->next.offset = sb->buf.offset + sb->buf.len;
+  sb->next.len = (sb->len >= 0 ? sb->len : sb->maxlen) - sb->buf.len;
+  dmsg (D_STREAM_DEBUG, "STREAM: SET NEXT, buf=[%d,%d] next=[%d,%d] len=%d maxlen=%d",
+       sb->buf.offset, sb->buf.len,
+       sb->next.offset, sb->next.len,
+       sb->len, sb->maxlen);
+  ASSERT (sb->next.len > 0);
+  ASSERT (buf_safe (&sb->buf, sb->next.len));
+}
+
+static inline void
+stream_buf_get_final (struct stream_buf *sb, struct buffer *buf)
+{
+  dmsg (D_STREAM_DEBUG, "STREAM: GET FINAL len=%d",
+       buf_defined (&sb->buf) ? sb->buf.len : -1);
+  ASSERT (buf_defined (&sb->buf));
+  *buf = sb->buf;
+}
+
+static inline void
+stream_buf_get_next (struct stream_buf *sb, struct buffer *buf)
+{
+  dmsg (D_STREAM_DEBUG, "STREAM: GET NEXT len=%d",
+       buf_defined (&sb->next) ? sb->next.len : -1);
+  ASSERT (buf_defined (&sb->next));
+  *buf = sb->next;
+}
+
+bool
+stream_buf_read_setup_dowork (struct link_socket* sock)
+{
+  if (sock->stream_buf.residual.len && !sock->stream_buf.residual_fully_formed)
+    {
+      ASSERT (buf_copy (&sock->stream_buf.buf, &sock->stream_buf.residual));
+      ASSERT (buf_init (&sock->stream_buf.residual, 0));
+      sock->stream_buf.residual_fully_formed = stream_buf_added (&sock->stream_buf, 0);
+      dmsg (D_STREAM_DEBUG, "STREAM: RESIDUAL FULLY FORMED [%s], len=%d",
+	   sock->stream_buf.residual_fully_formed ? "YES" : "NO",
+	   sock->stream_buf.residual.len);
+    }
+
+  if (!sock->stream_buf.residual_fully_formed)
+    stream_buf_set_next (&sock->stream_buf);
+  return !sock->stream_buf.residual_fully_formed;
+}
+
+bool
+stream_buf_added (struct stream_buf *sb,
+		  int length_added)
+{
+  dmsg (D_STREAM_DEBUG, "STREAM: ADD length_added=%d", length_added);
+  if (length_added > 0)
+    sb->buf.len += length_added;
+
+  /* if length unknown, see if we can get the length prefix from
+     the head of the buffer */
+  if (sb->len < 0 && sb->buf.len >= (int) sizeof (packet_size_type))
+    {
+      packet_size_type net_size;
+
+#if PORT_SHARE
+      if (sb->port_share_state == PS_ENABLED)
+	{
+	  if (!is_openvpn_protocol (&sb->buf))
+	    {
+	      msg (D_STREAM_ERRORS, "Non-OpenVPN client protocol detected");
+	      sb->port_share_state = PS_FOREIGN;
+	      sb->error = true;
+	      return false;
+	    }
+	  else
+	    sb->port_share_state = PS_DISABLED;
+	}
+#endif
+
+      ASSERT (buf_read (&sb->buf, &net_size, sizeof (net_size)));
+      sb->len = ntohps (net_size);
+
+      if (sb->len < 1 || sb->len > sb->maxlen)
+	{
+	  msg (M_WARN, "WARNING: Bad encapsulated packet length from peer (%d), which must be > 0 and <= %d -- please ensure that --tun-mtu or --link-mtu is equal on both peers -- this condition could also indicate a possible active attack on the TCP link -- [Attempting restart...]", sb->len, sb->maxlen);
+	  stream_buf_reset (sb);
+	  sb->error = true;
+	  return false;
+	}
+    }
+
+  /* is our incoming packet fully read? */
+  if (sb->len > 0 && sb->buf.len >= sb->len)
+    {
+      /* save any residual data that's part of the next packet */
+      ASSERT (buf_init (&sb->residual, 0));
+      if (sb->buf.len > sb->len)
+	  ASSERT (buf_copy_excess (&sb->residual, &sb->buf, sb->len));
+      dmsg (D_STREAM_DEBUG, "STREAM: ADD returned TRUE, buf_len=%d, residual_len=%d",
+	   BLEN (&sb->buf),
+	   BLEN (&sb->residual));
+      return true;
+    }
+  else
+    {
+      dmsg (D_STREAM_DEBUG, "STREAM: ADD returned FALSE (have=%d need=%d)", sb->buf.len, sb->len);
+      stream_buf_set_next (sb);
+      return false;
+    }
+}
+
+void
+stream_buf_close (struct stream_buf* sb)
+{
+  free_buf (&sb->residual);
+}
+
+/*
+ * The listen event is a special event whose sole purpose is
+ * to tell us that there's a new incoming connection on a
+ * TCP socket, for use in server mode.
+ */
+event_t
+socket_listen_event_handle (struct link_socket *s)
+{
+#ifdef WIN32
+  if (!defined_net_event_win32 (&s->listen_handle))
+    init_net_event_win32 (&s->listen_handle, FD_ACCEPT, s->sd, 0);
+  return &s->listen_handle;
+#else
+  return s->sd;
+#endif
+}
+
+/*
+ * Format IP addresses in ascii
+ */
+
+const char *
+print_sockaddr (const struct openvpn_sockaddr *addr, struct gc_arena *gc)
+{
+  return print_sockaddr_ex (addr, ":", PS_SHOW_PORT, gc);
+}
+
+const char *
+print_sockaddr_ex (const struct openvpn_sockaddr *addr,
+		   const char* separator,
+		   const unsigned int flags,
+		   struct gc_arena *gc)
+{
+  if (addr)
+    {
+      struct buffer out = alloc_buf_gc (64, gc);
+      const int port = ntohs (addr->sa.sin_port);
+
+      if (!(flags & PS_DONT_SHOW_ADDR))
+	buf_printf (&out, "%s", (addr_defined (addr) ? inet_ntoa (addr->sa.sin_addr) : "[undef]"));
+
+      if (((flags & PS_SHOW_PORT) || (addr_defined (addr) && (flags & PS_SHOW_PORT_IF_DEFINED)))
+	  && port)
+	{
+	  if (separator)
+	    buf_printf (&out, "%s", separator);
+
+	  buf_printf (&out, "%d", port);
+	}
+      return BSTR (&out);
+    }
+  else
+    return "[NULL]";
+}
+
+const char *
+print_link_socket_actual (const struct link_socket_actual *act, struct gc_arena *gc)
+{
+  return print_link_socket_actual_ex (act, ":", PS_SHOW_PORT|PS_SHOW_PKTINFO, gc);
+}
+
+const char *
+print_link_socket_actual_ex (const struct link_socket_actual *act,
+			     const char *separator,
+			     const unsigned int flags,
+			     struct gc_arena *gc)
+{
+  if (act)
+    {
+      struct buffer out = alloc_buf_gc (128, gc);
+      buf_printf (&out, "%s", print_sockaddr_ex (&act->dest, separator, flags, gc));
+#if ENABLE_IP_PKTINFO
+      if ((flags & PS_SHOW_PKTINFO) && act->pi.ipi_spec_dst.s_addr)
+	{
+	  struct openvpn_sockaddr sa;
+	  CLEAR (sa);
+	  sa.sa.sin_addr = act->pi.ipi_spec_dst;
+	  buf_printf (&out, " (via %s)", print_sockaddr_ex (&sa, separator, 0, gc));
+	}
+#endif
+      return BSTR (&out);
+    }
+  else
+    return "[NULL]";
+}
+
+/*
+ * Convert an in_addr_t in host byte order
+ * to an ascii dotted quad.
+ */
+const char *
+print_in_addr_t (in_addr_t addr, unsigned int flags, struct gc_arena *gc)
+{
+  struct in_addr ia;
+  struct buffer out = alloc_buf_gc (64, gc);
+
+  if (addr || !(flags & IA_EMPTY_IF_UNDEF))
+    {
+      CLEAR (ia);
+      ia.s_addr = (flags & IA_NET_ORDER) ? addr : htonl (addr);
+
+      buf_printf (&out, "%s", inet_ntoa (ia));
+    }
+  return BSTR (&out);
+}
+
+/* set environmental variables for ip/port in *addr */
+void
+setenv_sockaddr (struct env_set *es, const char *name_prefix, const struct openvpn_sockaddr *addr, const bool flags)
+{
+  char name_buf[256];
+
+  if (flags & SA_IP_PORT)
+    openvpn_snprintf (name_buf, sizeof (name_buf), "%s_ip", name_prefix);
+  else
+    openvpn_snprintf (name_buf, sizeof (name_buf), "%s", name_prefix);
+
+  setenv_str (es, name_buf, inet_ntoa (addr->sa.sin_addr));
+
+  if ((flags & SA_IP_PORT) && addr->sa.sin_port)
+    {
+      openvpn_snprintf (name_buf, sizeof (name_buf), "%s_port", name_prefix);
+      setenv_int (es, name_buf, ntohs (addr->sa.sin_port));
+    }
+}
+
+void
+setenv_in_addr_t (struct env_set *es, const char *name_prefix, in_addr_t addr, const bool flags)
+{
+  if (addr || !(flags & SA_SET_IF_NONZERO))
+    {
+      struct openvpn_sockaddr si;
+      CLEAR (si);
+      si.sa.sin_addr.s_addr = htonl (addr);
+      setenv_sockaddr (es, name_prefix, &si, flags);
+    }
+}
+
+void
+setenv_link_socket_actual (struct env_set *es,
+			   const char *name_prefix,
+			   const struct link_socket_actual *act,
+			   const bool flags)
+{
+  setenv_sockaddr (es, name_prefix, &act->dest, flags);
+}
+
+/*
+ * Convert protocol names between index and ascii form.
+ */
+
+struct proto_names {
+  const char *short_form;
+  const char *display_form;
+};
+
+/* Indexed by PROTO_x */
+static const struct proto_names proto_names[] = {
+  {"udp",        "UDPv4"},
+  {"tcp-server", "TCPv4_SERVER"},
+  {"tcp-client", "TCPv4_CLIENT"},
+  {"tcp",        "TCPv4"}
+};
+
+int
+ascii2proto (const char* proto_name)
+{
+  int i;
+  ASSERT (PROTO_N == SIZE (proto_names));
+  for (i = 0; i < PROTO_N; ++i)
+    if (!strcmp (proto_name, proto_names[i].short_form))
+      return i;
+  return -1;
+}
+
+const char *
+proto2ascii (int proto, bool display_form)
+{
+  ASSERT (PROTO_N == SIZE (proto_names));
+  if (proto < 0 || proto >= PROTO_N)
+    return "[unknown protocol]";
+  else if (display_form)
+    return proto_names[proto].display_form;
+  else
+    return proto_names[proto].short_form;
+}
+
+const char *
+proto2ascii_all (struct gc_arena *gc)
+{
+  struct buffer out = alloc_buf_gc (256, gc);
+  int i;
+
+  ASSERT (PROTO_N == SIZE (proto_names));
+  for (i = 0; i < PROTO_N; ++i)
+    {
+      if (i)
+	buf_printf(&out, " ");
+      buf_printf(&out, "[%s]", proto2ascii(i, false));
+    }
+  return BSTR (&out);
+}
+
+/*
+ * Given a local proto, return local proto
+ * if !remote, or compatible remote proto
+ * if remote.
+ *
+ * This is used for options compatibility
+ * checking.
+ */
+int
+proto_remote (int proto, bool remote)
+{
+  ASSERT (proto >= 0 && proto < PROTO_N);
+  if (remote)
+    {
+      if (proto == PROTO_TCPv4_SERVER)
+	return PROTO_TCPv4_CLIENT;
+      if (proto == PROTO_TCPv4_CLIENT)
+	return PROTO_TCPv4_SERVER;
+    }
+  return proto;
+}
+
+/*
+ * Bad incoming address lengths that differ from what
+ * we expect are considered to be fatal errors.
+ */
+void
+bad_address_length (int actual, int expected)
+{
+  msg (M_FATAL, "ERROR: received strange incoming packet with an address length of %d -- we only accept address lengths of %d.",
+       actual,
+       expected);
+}
+
+/*
+ * Socket Read Routines
+ */
+
+int
+link_socket_read_tcp (struct link_socket *sock,
+		      struct buffer *buf)
+{
+  int len = 0;
+
+  if (!sock->stream_buf.residual_fully_formed)
+    {
+#ifdef WIN32
+      len = socket_finalize (sock->sd, &sock->reads, buf, NULL);
+#else
+      struct buffer frag;
+      stream_buf_get_next (&sock->stream_buf, &frag);
+      len = recv (sock->sd, BPTR (&frag), BLEN (&frag), MSG_NOSIGNAL);
+#endif
+
+      if (!len)
+	sock->stream_reset = true;
+      if (len <= 0)
+	return buf->len = len;
+    }
+
+  if (sock->stream_buf.residual_fully_formed
+      || stream_buf_added (&sock->stream_buf, len)) /* packet complete? */
+    {
+      stream_buf_get_final (&sock->stream_buf, buf);
+      stream_buf_reset (&sock->stream_buf);
+      return buf->len;
+    }
+  else
+    return buf->len = 0; /* no error, but packet is still incomplete */
+}
+
+#ifndef WIN32
+
+#if ENABLE_IP_PKTINFO
+
+#pragma pack(1) /* needed to keep structure size consistent for 32 vs. 64-bit architectures */
+struct openvpn_pktinfo
+{
+  struct cmsghdr cmsghdr;
+  struct in_pktinfo in_pktinfo;
+};
+#pragma pack()
+
+static socklen_t
+link_socket_read_udp_posix_recvmsg (struct link_socket *sock,
+				    struct buffer *buf,
+				    int maxsize,
+				    struct link_socket_actual *from)
+{
+  struct iovec iov;
+  struct openvpn_pktinfo opi;
+  struct msghdr mesg;
+  socklen_t fromlen = sizeof (from->dest.sa);
+
+  iov.iov_base = BPTR (buf);
+  iov.iov_len = maxsize;
+  mesg.msg_iov = &iov;
+  mesg.msg_iovlen = 1;
+  mesg.msg_name = &from->dest.sa;
+  mesg.msg_namelen = fromlen;
+  mesg.msg_control = &opi;
+  mesg.msg_controllen = sizeof (opi);
+  buf->len = recvmsg (sock->sd, &mesg, 0);
+  if (buf->len >= 0)
+    {
+      struct cmsghdr *cmsg;
+      fromlen = mesg.msg_namelen;
+      cmsg = CMSG_FIRSTHDR (&mesg);
+      if (cmsg != NULL
+	  && CMSG_NXTHDR (&mesg, cmsg) == NULL
+	  && cmsg->cmsg_level == SOL_IP 
+	  && cmsg->cmsg_type == IP_PKTINFO
+	  && cmsg->cmsg_len >= sizeof (opi))
+	{
+	  struct in_pktinfo *pkti = (struct in_pktinfo *) CMSG_DATA (cmsg);
+	  from->pi.ipi_ifindex = pkti->ipi_ifindex;
+	  from->pi.ipi_spec_dst = pkti->ipi_spec_dst;
+	}
+    }
+  return fromlen;
+}
+#endif
+
+int
+link_socket_read_udp_posix (struct link_socket *sock,
+			    struct buffer *buf,
+			    int maxsize,
+			    struct link_socket_actual *from)
+{
+  socklen_t fromlen = sizeof (from->dest.sa);
+  from->dest.sa.sin_addr.s_addr = 0;
+  ASSERT (buf_safe (buf, maxsize));
+#if ENABLE_IP_PKTINFO
+  if (sock->sockflags & SF_USE_IP_PKTINFO)
+    fromlen = link_socket_read_udp_posix_recvmsg (sock, buf, maxsize, from);
+  else
+#endif
+    buf->len = recvfrom (sock->sd, BPTR (buf), maxsize, 0,
+			 (struct sockaddr *) &from->dest.sa, &fromlen);
+  if (fromlen != sizeof (from->dest.sa))
+    bad_address_length (fromlen, sizeof (from->dest.sa));
+  return buf->len;
+}
+
+#endif
+
+/*
+ * Socket Write Routines
+ */
+
+int
+link_socket_write_tcp (struct link_socket *sock,
+		       struct buffer *buf,
+		       struct link_socket_actual *to)
+{
+  packet_size_type len = BLEN (buf);
+  dmsg (D_STREAM_DEBUG, "STREAM: WRITE %d offset=%d", (int)len, buf->offset);
+  ASSERT (len <= sock->stream_buf.maxlen);
+  len = htonps (len);
+  ASSERT (buf_write_prepend (buf, &len, sizeof (len)));
+#ifdef WIN32
+  return link_socket_write_win32 (sock, buf, to);
+#else
+  return link_socket_write_tcp_posix (sock, buf, to);  
+#endif
+}
+
+#if ENABLE_IP_PKTINFO
+
+int
+link_socket_write_udp_posix_sendmsg (struct link_socket *sock,
+				     struct buffer *buf,
+				     struct link_socket_actual *to)
+{
+  struct iovec iov;
+  struct msghdr mesg;
+  struct cmsghdr *cmsg;
+  struct in_pktinfo *pkti;
+  struct openvpn_pktinfo opi;
+
+  iov.iov_base = BPTR (buf);
+  iov.iov_len = BLEN (buf);
+  mesg.msg_iov = &iov;
+  mesg.msg_iovlen = 1;
+  mesg.msg_name = &to->dest.sa;
+  mesg.msg_namelen = sizeof (to->dest.sa);
+  mesg.msg_control = &opi;
+  mesg.msg_controllen = sizeof (opi);
+  mesg.msg_flags = 0;
+  cmsg = CMSG_FIRSTHDR (&mesg);
+  cmsg->cmsg_len = sizeof (opi);
+  cmsg->cmsg_level = SOL_IP;
+  cmsg->cmsg_type = IP_PKTINFO;
+  pkti = (struct in_pktinfo *) CMSG_DATA (cmsg);
+  pkti->ipi_ifindex = to->pi.ipi_ifindex;
+  pkti->ipi_spec_dst = to->pi.ipi_spec_dst;
+  pkti->ipi_addr.s_addr = 0;
+  return sendmsg (sock->sd, &mesg, 0);
+}
+
+#endif
+
+/*
+ * Win32 overlapped socket I/O functions.
+ */
+
+#ifdef WIN32
+
+int
+socket_recv_queue (struct link_socket *sock, int maxsize)
+{
+  if (sock->reads.iostate == IOSTATE_INITIAL)
+    {
+      WSABUF wsabuf[1];
+      int status;
+
+      /* reset buf to its initial state */
+      if (sock->info.proto == PROTO_UDPv4)
+	{
+	  sock->reads.buf = sock->reads.buf_init;
+	}
+      else if (sock->info.proto == PROTO_TCPv4_CLIENT || sock->info.proto == PROTO_TCPv4_SERVER)
+	{
+	  stream_buf_get_next (&sock->stream_buf, &sock->reads.buf);
+	}
+      else
+	{
+	  ASSERT (0);
+	}
+
+      /* Win32 docs say it's okay to allocate the wsabuf on the stack */
+      wsabuf[0].buf = BPTR (&sock->reads.buf);
+      wsabuf[0].len = maxsize ? maxsize : BLEN (&sock->reads.buf);
+
+      /* check for buffer overflow */
+      ASSERT (wsabuf[0].len <= BLEN (&sock->reads.buf));
+
+      /* the overlapped read will signal this event on I/O completion */
+      ASSERT (ResetEvent (sock->reads.overlapped.hEvent));
+      sock->reads.flags = 0;
+
+      if (sock->info.proto == PROTO_UDPv4)
+	{
+	  sock->reads.addr_defined = true;
+	  sock->reads.addrlen = sizeof (sock->reads.addr);
+	  status = WSARecvFrom(
+			       sock->sd,
+			       wsabuf,
+			       1,
+			       &sock->reads.size,
+			       &sock->reads.flags,
+			       (struct sockaddr *) &sock->reads.addr,
+			       &sock->reads.addrlen,
+			       &sock->reads.overlapped,
+			       NULL);
+	}
+      else if (sock->info.proto == PROTO_TCPv4_CLIENT || sock->info.proto == PROTO_TCPv4_SERVER)
+	{
+	  sock->reads.addr_defined = false;
+	  status = WSARecv(
+			   sock->sd,
+			   wsabuf,
+			   1,
+			   &sock->reads.size,
+			   &sock->reads.flags,
+			   &sock->reads.overlapped,
+			   NULL);
+	}
+      else
+	{
+	  status = 0;
+	  ASSERT (0);
+	}
+
+      if (!status) /* operation completed immediately? */
+	{
+	  if (sock->reads.addr_defined && sock->reads.addrlen != sizeof (sock->reads.addr))
+	    bad_address_length (sock->reads.addrlen, sizeof (sock->reads.addr));
+
+	  sock->reads.iostate = IOSTATE_IMMEDIATE_RETURN;
+
+	  /* since we got an immediate return, we must signal the event object ourselves */
+	  ASSERT (SetEvent (sock->reads.overlapped.hEvent));
+	  sock->reads.status = 0;
+
+	  dmsg (D_WIN32_IO, "WIN32 I/O: Socket Receive immediate return [%d,%d]",
+	       (int) wsabuf[0].len,
+	       (int) sock->reads.size);	       
+	}
+      else
+	{
+	  status = WSAGetLastError (); 
+	  if (status == WSA_IO_PENDING) /* operation queued? */
+	    {
+	      sock->reads.iostate = IOSTATE_QUEUED;
+	      sock->reads.status = status;
+	      dmsg (D_WIN32_IO, "WIN32 I/O: Socket Receive queued [%d]",
+		   (int) wsabuf[0].len);
+	    }
+	  else /* error occurred */
+	    {
+	      struct gc_arena gc = gc_new ();
+	      ASSERT (SetEvent (sock->reads.overlapped.hEvent));
+	      sock->reads.iostate = IOSTATE_IMMEDIATE_RETURN;
+	      sock->reads.status = status;
+	      dmsg (D_WIN32_IO, "WIN32 I/O: Socket Receive error [%d]: %s",
+		   (int) wsabuf[0].len,
+		   strerror_win32 (status, &gc));
+	      gc_free (&gc);
+	    }
+	}
+    }
+  return sock->reads.iostate;
+}
+
+int
+socket_send_queue (struct link_socket *sock, struct buffer *buf, const struct link_socket_actual *to)
+{
+  if (sock->writes.iostate == IOSTATE_INITIAL)
+    {
+      WSABUF wsabuf[1];
+      int status;
+ 
+      /* make a private copy of buf */
+      sock->writes.buf = sock->writes.buf_init;
+      sock->writes.buf.len = 0;
+      ASSERT (buf_copy (&sock->writes.buf, buf));
+
+      /* Win32 docs say it's okay to allocate the wsabuf on the stack */
+      wsabuf[0].buf = BPTR (&sock->writes.buf);
+      wsabuf[0].len = BLEN (&sock->writes.buf);
+
+      /* the overlapped write will signal this event on I/O completion */
+      ASSERT (ResetEvent (sock->writes.overlapped.hEvent));
+      sock->writes.flags = 0;
+
+      if (sock->info.proto == PROTO_UDPv4)
+	{
+	  /* set destination address for UDP writes */
+	  sock->writes.addr_defined = true;
+	  sock->writes.addr = to->dest.sa;
+	  sock->writes.addrlen = sizeof (sock->writes.addr);
+
+	  status = WSASendTo(
+			       sock->sd,
+			       wsabuf,
+			       1,
+			       &sock->writes.size,
+			       sock->writes.flags,
+			       (struct sockaddr *) &sock->writes.addr,
+			       sock->writes.addrlen,
+			       &sock->writes.overlapped,
+			       NULL);
+	}
+      else if (sock->info.proto == PROTO_TCPv4_CLIENT || sock->info.proto == PROTO_TCPv4_SERVER)
+	{
+	  /* destination address for TCP writes was established on connection initiation */
+	  sock->writes.addr_defined = false;
+
+	  status = WSASend(
+			   sock->sd,
+			   wsabuf,
+			   1,
+			   &sock->writes.size,
+			   sock->writes.flags,
+			   &sock->writes.overlapped,
+			   NULL);
+	}
+      else 
+	{
+	  status = 0;
+	  ASSERT (0);
+	}
+
+      if (!status) /* operation completed immediately? */
+	{
+	  sock->writes.iostate = IOSTATE_IMMEDIATE_RETURN;
+
+	  /* since we got an immediate return, we must signal the event object ourselves */
+	  ASSERT (SetEvent (sock->writes.overlapped.hEvent));
+
+	  sock->writes.status = 0;
+
+	  dmsg (D_WIN32_IO, "WIN32 I/O: Socket Send immediate return [%d,%d]",
+	       (int) wsabuf[0].len,
+	       (int) sock->writes.size);	       
+	}
+      else
+	{
+	  status = WSAGetLastError (); 
+	  if (status == WSA_IO_PENDING) /* operation queued? */
+	    {
+	      sock->writes.iostate = IOSTATE_QUEUED;
+	      sock->writes.status = status;
+	      dmsg (D_WIN32_IO, "WIN32 I/O: Socket Send queued [%d]",
+		   (int) wsabuf[0].len);
+	    }
+	  else /* error occurred */
+	    {
+	      struct gc_arena gc = gc_new ();
+	      ASSERT (SetEvent (sock->writes.overlapped.hEvent));
+	      sock->writes.iostate = IOSTATE_IMMEDIATE_RETURN;
+	      sock->writes.status = status;
+
+	      dmsg (D_WIN32_IO, "WIN32 I/O: Socket Send error [%d]: %s",
+		   (int) wsabuf[0].len,
+		   strerror_win32 (status, &gc));
+
+	      gc_free (&gc);
+	    }
+	}
+    }
+  return sock->writes.iostate;
+}
+
+int
+socket_finalize (SOCKET s,
+		 struct overlapped_io *io,
+		 struct buffer *buf,
+		 struct link_socket_actual *from)
+{
+  int ret = -1;
+  BOOL status;
+
+  switch (io->iostate)
+    {
+    case IOSTATE_QUEUED:
+      status = WSAGetOverlappedResult(
+				      s,
+				      &io->overlapped,
+				      &io->size,
+				      FALSE,
+				      &io->flags
+				      );
+      if (status)
+	{
+	  /* successful return for a queued operation */
+	  if (buf)
+	    *buf = io->buf;
+	  ret = io->size;
+	  io->iostate = IOSTATE_INITIAL;
+	  ASSERT (ResetEvent (io->overlapped.hEvent));
+
+	  dmsg (D_WIN32_IO, "WIN32 I/O: Socket Completion success [%d]", ret);
+	}
+      else
+	{
+	  /* error during a queued operation */
+	  ret = -1;
+	  if (WSAGetLastError() != WSA_IO_INCOMPLETE)
+	    {
+	      /* if no error (i.e. just not finished yet), then DON'T execute this code */
+	      io->iostate = IOSTATE_INITIAL;
+	      ASSERT (ResetEvent (io->overlapped.hEvent));
+	      msg (D_WIN32_IO | M_ERRNO_SOCK, "WIN32 I/O: Socket Completion error");
+	    }
+	}
+      break;
+
+    case IOSTATE_IMMEDIATE_RETURN:
+      io->iostate = IOSTATE_INITIAL;
+      ASSERT (ResetEvent (io->overlapped.hEvent));
+      if (io->status)
+	{
+	  /* error return for a non-queued operation */
+	  WSASetLastError (io->status);
+	  ret = -1;
+	  msg (D_WIN32_IO | M_ERRNO_SOCK, "WIN32 I/O: Socket Completion non-queued error");
+	}
+      else
+	{
+	  /* successful return for a non-queued operation */
+	  if (buf)
+	    *buf = io->buf;
+	  ret = io->size;
+	  dmsg (D_WIN32_IO, "WIN32 I/O: Socket Completion non-queued success [%d]", ret);
+	}
+      break;
+
+    case IOSTATE_INITIAL: /* were we called without proper queueing? */
+      WSASetLastError (WSAEINVAL);
+      ret = -1;
+      dmsg (D_WIN32_IO, "WIN32 I/O: Socket Completion BAD STATE");
+      break;
+
+    default:
+      ASSERT (0);
+    }
+  
+  /* return from address if requested */
+  if (from)
+    {
+      if (ret >= 0 && io->addr_defined)
+	{
+	  if (io->addrlen != sizeof (io->addr))
+	    bad_address_length (io->addrlen, sizeof (io->addr));
+	  from->dest.sa = io->addr;
+	}
+      else
+	CLEAR (from->dest.sa);
+    }
+  
+  if (buf)
+    buf->len = ret;
+  return ret;
+}
+
+#endif /* WIN32 */
+
+/*
+ * Socket event notification
+ */
+
+unsigned int
+socket_set (struct link_socket *s,
+	    struct event_set *es,
+	    unsigned int rwflags,
+	    void *arg,
+	    unsigned int *persistent)
+{
+  if (s)
+    {
+      if ((rwflags & EVENT_READ) && !stream_buf_read_setup (s))
+	{
+	  ASSERT (!persistent);
+	  rwflags &= ~EVENT_READ;
+	}
+      
+#ifdef WIN32
+      if (rwflags & EVENT_READ)
+	socket_recv_queue (s, 0);
+#endif
+
+      /* if persistent is defined, call event_ctl only if rwflags has changed since last call */
+      if (!persistent || *persistent != rwflags)
+	{
+	  event_ctl (es, socket_event_handle (s), rwflags, arg);
+	  if (persistent)
+	    *persistent = rwflags;
+	}
+
+      s->rwflags_debug = rwflags;
+    }
+  return rwflags;
+}
+
+void
+sd_close (socket_descriptor_t *sd)
+{
+  if (sd && socket_defined (*sd))
+    {
+      openvpn_close_socket (*sd);
+      *sd = SOCKET_UNDEFINED;
+    }
+}
+
+#if UNIX_SOCK_SUPPORT
+
+/*
+ * code for unix domain sockets
+ */
+
+const char *
+sockaddr_unix_name (const struct sockaddr_un *local, const char *null)
+{
+  if (local && local->sun_family == PF_UNIX)
+    return local->sun_path;
+  else
+    return null;
+}
+
+socket_descriptor_t
+create_socket_unix (void)
+{
+  socket_descriptor_t sd;
+
+  if ((sd = socket (PF_UNIX, SOCK_STREAM, 0)) < 0)
+    msg (M_SOCKERR, "Cannot create unix domain socket");
+  return sd;
+}
+
+void
+socket_bind_unix (socket_descriptor_t sd,
+		  struct sockaddr_un *local,
+		  const char *prefix)
+{
+  struct gc_arena gc = gc_new ();
+
+#ifdef HAVE_UMASK
+  const mode_t orig_umask = umask (0);
+#endif
+
+  if (bind (sd, (struct sockaddr *) local, sizeof (struct sockaddr_un)))
+    {
+      const int errnum = openvpn_errno_socket ();
+      msg (M_FATAL, "%s: Socket bind[%d] failed on unix domain socket %s: %s",
+	   prefix,
+	   (int)sd,
+           sockaddr_unix_name (local, "NULL"),
+           strerror_ts (errnum, &gc));
+    }
+
+#ifdef HAVE_UMASK
+  umask (orig_umask);
+#endif
+
+  gc_free (&gc);
+}
+
+socket_descriptor_t
+socket_accept_unix (socket_descriptor_t sd,
+		    struct sockaddr_un *remote)
+{
+  socklen_t remote_len = sizeof (struct sockaddr_un);
+  socket_descriptor_t ret;
+
+  CLEAR (*remote);
+  ret = accept (sd, (struct sockaddr *) remote, &remote_len);
+  return ret;
+}
+
+int
+socket_connect_unix (socket_descriptor_t sd,
+		     struct sockaddr_un *remote)
+{
+  int status = connect (sd, (struct sockaddr *) remote, sizeof (struct sockaddr_un));
+  if (status)
+    status = openvpn_errno_socket ();
+  return status;
+}
+
+void
+sockaddr_unix_init (struct sockaddr_un *local, const char *path)
+{
+  local->sun_family = PF_UNIX;
+  strncpynt (local->sun_path, path, sizeof (local->sun_path));
+}
+
+void
+socket_delete_unix (const struct sockaddr_un *local)
+{
+  const char *name = sockaddr_unix_name (local, NULL);
+#ifdef HAVE_UNLINK
+  if (name && strlen (name))
+    unlink (name);
+#endif
+}
+
+bool
+unix_socket_get_peer_uid_gid (const socket_descriptor_t sd, int *uid, int *gid)
+{
+#ifdef HAVE_GETPEEREID
+  uid_t u;
+  gid_t g;
+  if (getpeereid (sd, &u, &g) == -1) 
+    return false;
+  if (uid)
+    *uid = u;
+  if (gid)
+    *gid = g;
+  return true;
+#elif defined(SO_PEERCRED)
+  struct ucred peercred;
+  socklen_t so_len = sizeof(peercred);
+  if (getsockopt(sd, SOL_SOCKET, SO_PEERCRED, &peercred, &so_len) == -1) 
+    return false;
+  if (uid)
+    *uid = peercred.uid;
+  if (gid)
+    *gid = peercred.gid;
+  return true;
+#else
+  return false;
+#endif
+}
+
+#endif