Imported Upstream version 2.2.1upstream/2.2.1

1 files changed, 880 insertions, 0 deletions

diff --git a/ps.c b/ps.c
new file mode 100644
index 0000000..5533341
--- /dev/null
+++ b/ps.c
@@ -0,0 +1,880 @@
+/*
+ *  OpenVPN -- An application to securely tunnel IP networks
+ *             over a single UDP port, with support for SSL/TLS-based
+ *             session authentication and key exchange,
+ *             packet encryption, packet authentication, and
+ *             packet compression.
+ *
+ *  Copyright (C) 2002-2010 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"
+
+#if PORT_SHARE
+
+#include "event.h"
+#include "socket.h"
+#include "fdmisc.h"
+#include "crypto.h"
+#include "ps.h"
+
+#include "memdbg.h"
+
+struct port_share *port_share = NULL; /* GLOBAL */
+
+/* size of i/o buffers */
+#define PROXY_CONNECTION_BUFFER_SIZE 1500
+
+/* Command codes for foreground -> background communication */
+#define COMMAND_REDIRECT 10
+#define COMMAND_EXIT     11
+
+/* Response codes for background -> foreground communication */
+#define RESPONSE_INIT_SUCCEEDED   20
+#define RESPONSE_INIT_FAILED      21
+
+/*
+ * Return values for proxy_connection_io functions
+ */
+
+#define IOSTAT_EAGAIN_ON_READ   0 /* recv returned EAGAIN */
+#define IOSTAT_EAGAIN_ON_WRITE  1 /* send returned EAGAIN */
+#define IOSTAT_READ_ERROR       2 /* the other end of our read socket (pc) was closed */
+#define IOSTAT_WRITE_ERROR      3 /* the other end of our write socket (pc->counterpart) was closed */
+#define IOSTAT_GOOD             4 /* nothing to report */
+
+/*
+ * A foreign (non-OpenVPN) connection we are proxying,
+ * usually HTTPS
+ */
+struct proxy_connection {
+  bool defined;
+  struct proxy_connection *next;
+  struct proxy_connection *counterpart;
+  struct buffer buf;
+  bool buffer_initial;
+  int rwflags;
+  int sd;
+};
+
+#if 0
+static const char *
+headc (const struct buffer *buf)
+{
+  static char foo[16];
+  strncpy (foo, BSTR(buf), 15);
+  foo[15] = 0;
+  return foo;
+}
+#endif
+
+static inline void
+close_socket_if_defined (const socket_descriptor_t sd)
+{
+  if (socket_defined (sd))
+    openvpn_close_socket (sd);
+}
+
+/*
+ * Close most of parent's fds.
+ * Keep stdin/stdout/stderr, plus one
+ * other fd which is presumed to be
+ * our pipe back to parent.
+ * Admittedly, a bit of a kludge,
+ * but posix doesn't give us a kind
+ * of FD_CLOEXEC which will stop
+ * fds from crossing a fork().
+ */
+static void
+close_fds_except (int keep)
+{
+  socket_descriptor_t i;
+  closelog ();
+  for (i = 3; i <= 100; ++i)
+    {
+      if (i != keep)
+	openvpn_close_socket (i);
+    }
+}
+
+/*
+ * Usually we ignore signals, because our parent will
+ * deal with them.
+ */
+static void
+set_signals (void)
+{
+  signal (SIGTERM, SIG_DFL);
+
+  signal (SIGINT, SIG_IGN);
+  signal (SIGHUP, SIG_IGN);
+  signal (SIGUSR1, SIG_IGN);
+  signal (SIGUSR2, SIG_IGN);
+  signal (SIGPIPE, SIG_IGN);
+}
+
+/*
+ * Socket read/write functions.
+ */
+
+static int
+recv_control (const socket_descriptor_t fd)
+{
+  unsigned char c;
+  const ssize_t size = read (fd, &c, sizeof (c));
+  if (size == sizeof (c))
+    return c;
+  else
+    {
+      return -1;
+    }
+}
+
+static int
+send_control (const socket_descriptor_t fd, int code)
+{
+  unsigned char c = (unsigned char) code;
+  const ssize_t size = write (fd, &c, sizeof (c));
+  if (size == sizeof (c))
+    return (int) size;
+  else
+    return -1;
+}
+
+static int
+cmsg_size ()
+{
+  return CMSG_SPACE(sizeof(socket_descriptor_t));
+}
+
+/*
+ * Send a command (char), data (head), and a file descriptor (sd_send) to a local process
+ * over unix socket sd.  Unfortunately, there's no portable way to send file descriptors
+ * to other processes, so this code, as well as its analog (control_message_from_parent below),
+ * is Linux-specific. This function runs in the context of the main process and is used to
+ * send commands, data, and file descriptors to the background process.
+ */
+static void
+port_share_sendmsg (const socket_descriptor_t sd,
+		    const char command,
+		    const struct buffer *head,
+		    const socket_descriptor_t sd_send)
+{
+  if (socket_defined (sd))
+    {
+      struct msghdr mesg;
+      struct cmsghdr* h;
+      struct iovec iov[2];
+      socket_descriptor_t sd_null[2] = { SOCKET_UNDEFINED, SOCKET_UNDEFINED };
+      char cmd;
+      ssize_t status;
+
+      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: sendmsg sd=%d len=%d",
+	    (int)sd_send,
+	    head ? BLEN(head) : -1);
+
+      CLEAR (mesg);
+
+      cmd = command;
+
+      iov[0].iov_base = &cmd;
+      iov[0].iov_len = sizeof (cmd);
+      mesg.msg_iovlen = 1;
+
+      if (head)
+	{
+	  iov[1].iov_base = BPTR (head);
+	  iov[1].iov_len = BLEN (head);
+	  mesg.msg_iovlen = 2;
+	}
+
+      mesg.msg_iov = iov;
+
+      mesg.msg_controllen = cmsg_size ();
+      mesg.msg_control = (char *) malloc (mesg.msg_controllen);
+      check_malloc_return (mesg.msg_control);
+      mesg.msg_flags = 0;
+
+      h = CMSG_FIRSTHDR(&mesg);
+      h->cmsg_level = SOL_SOCKET;
+      h->cmsg_type = SCM_RIGHTS;
+      h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
+
+      if (socket_defined (sd_send))
+	{
+	  *((socket_descriptor_t*)CMSG_DATA(h)) = sd_send;
+	}
+      else
+	{
+	  socketpair (PF_UNIX, SOCK_DGRAM, 0, sd_null);
+	  *((socket_descriptor_t*)CMSG_DATA(h)) = sd_null[0];
+	}
+
+      status = sendmsg (sd, &mesg, MSG_NOSIGNAL);
+      if (status == -1)
+	msg (M_WARN, "PORT SHARE: sendmsg failed (unable to communicate with background process)");
+
+      close_socket_if_defined (sd_null[0]);
+      close_socket_if_defined (sd_null[1]);
+      free (mesg.msg_control);
+    }
+}
+
+static void
+proxy_entry_close_sd (struct proxy_connection *pc, struct event_set *es)
+{
+  if (pc->defined && socket_defined (pc->sd))
+    {
+      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: delete sd=%d", (int)pc->sd);
+      if (es)
+	event_del (es, pc->sd);
+      openvpn_close_socket (pc->sd);
+      pc->sd = SOCKET_UNDEFINED;
+    }
+}
+
+/*
+ * Mark a proxy entry and its counterpart for close.
+ */
+static void
+proxy_entry_mark_for_close (struct proxy_connection *pc, struct event_set *es)
+{
+  if (pc->defined)
+    {
+      struct proxy_connection *cp = pc->counterpart;
+      proxy_entry_close_sd (pc, es);
+      free_buf (&pc->buf);
+      pc->buffer_initial = false;
+      pc->rwflags = 0;
+      pc->defined = false;
+      if (cp && cp->defined && cp->counterpart == pc)
+	proxy_entry_mark_for_close (cp, es);
+    }
+}
+
+/*
+ * Run through the proxy entry list and delete all entries marked
+ * for close.
+ */
+static void
+proxy_list_housekeeping (struct proxy_connection **list)
+{
+  if (list)
+    {
+      struct proxy_connection *prev = NULL;
+      struct proxy_connection *pc = *list;
+
+      while (pc)
+	{
+	  struct proxy_connection *next = pc->next;
+	  if (!pc->defined)
+	    {
+	      free (pc);
+	      if (prev)
+		prev->next = next;
+	      else
+		*list = next;
+	    }
+	  else
+	    prev = pc;
+	  pc = next;
+	}
+    }
+}
+
+/*
+ * Cleanup function, on proxy process exit.
+ */
+static void
+proxy_list_close (struct proxy_connection **list)
+{
+  if (list)
+    {
+      struct proxy_connection *pc = *list;
+      while (pc)
+	{
+	  proxy_entry_mark_for_close (pc, NULL);
+	  pc = pc->next;
+	}
+      proxy_list_housekeeping (list);
+    }
+}
+
+static void
+sock_addr_set (struct openvpn_sockaddr *osaddr,
+	       const in_addr_t addr,
+	       const int port)
+{
+  CLEAR (*osaddr);
+  osaddr->sa.sin_family = AF_INET;
+  osaddr->sa.sin_addr.s_addr = htonl (addr);
+  osaddr->sa.sin_port = htons (port);
+}
+
+static inline void
+proxy_connection_io_requeue (struct proxy_connection *pc, const int rwflags_new, struct event_set *es)
+{
+  if (socket_defined (pc->sd) && pc->rwflags != rwflags_new)
+    {
+      /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: requeue[%d] rwflags=%d", (int)pc->sd, rwflags_new);*/
+      event_ctl (es, pc->sd, rwflags_new, (void*)pc);
+      pc->rwflags = rwflags_new;
+    }
+}
+
+/*
+ * Create a new pair of proxy_connection entries, one for each
+ * socket file descriptor involved in the proxy.  We are given
+ * the client fd, and we should derive our own server fd by connecting
+ * to the server given by server_addr/server_port.  Return true
+ * on success and false on failure to connect to server.
+ */
+static bool
+proxy_entry_new (struct proxy_connection **list,
+		 struct event_set *es,
+		 const in_addr_t server_addr,
+		 const int server_port,
+		 const socket_descriptor_t sd_client,
+		 struct buffer *initial_data)
+{
+  struct openvpn_sockaddr osaddr;
+  socket_descriptor_t sd_server;
+  int status;
+  struct proxy_connection *pc;
+  struct proxy_connection *cp;
+
+  /* connect to port share server */
+  sock_addr_set (&osaddr, server_addr, server_port);
+  sd_server = create_socket_tcp ();
+  status = openvpn_connect (sd_server, &osaddr, 5, NULL);
+  if (status)
+    {
+      msg (M_WARN, "PORT SHARE PROXY: connect to port-share server failed");
+      openvpn_close_socket (sd_server);
+      return false;
+    }
+  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: connect to port-share server succeeded");
+
+  set_nonblock (sd_client);
+  set_nonblock (sd_server);
+
+  /* allocate 2 new proxy_connection objects */
+  ALLOC_OBJ_CLEAR (pc, struct proxy_connection);
+  ALLOC_OBJ_CLEAR (cp, struct proxy_connection);
+
+  /* client object */
+  pc->defined = true;
+  pc->next = cp;
+  pc->counterpart = cp;
+  pc->buf = *initial_data;
+  pc->buffer_initial = true;
+  pc->rwflags = EVENT_UNDEF;
+  pc->sd = sd_client;
+
+  /* server object */
+  cp->defined = true;
+  cp->next = *list;
+  cp->counterpart = pc;
+  cp->buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
+  cp->buffer_initial = false;
+  cp->rwflags = EVENT_UNDEF;
+  cp->sd = sd_server;
+
+  /* add to list */
+  *list = pc;
+  
+  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: NEW CONNECTION [c=%d s=%d]", (int)sd_client, (int)sd_server);
+
+  /* set initial i/o states */
+  proxy_connection_io_requeue (pc, EVENT_READ, es);
+  proxy_connection_io_requeue (cp, EVENT_READ|EVENT_WRITE, es);
+  
+  return true;
+}
+
+/*
+ * This function runs in the context of the background proxy process.
+ * Receive a control message from the parent (sent by the port_share_sendmsg
+ * function above) and act on it.  Return false if the proxy process should
+ * exit, true otherwise.
+ */
+static bool
+control_message_from_parent (const socket_descriptor_t sd_control,
+			     struct proxy_connection **list,
+			     struct event_set *es,
+			     const in_addr_t server_addr,
+			     const int server_port)
+{
+  struct buffer buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
+  struct msghdr mesg;
+  struct cmsghdr* h;
+  struct iovec iov[2];
+  char command = 0;
+  ssize_t status;
+  int ret = true;
+
+  CLEAR (mesg);
+
+  iov[0].iov_base = &command;
+  iov[0].iov_len = sizeof (command);
+  iov[1].iov_base = BPTR (&buf);
+  iov[1].iov_len = BCAP (&buf);
+  mesg.msg_iov = iov;
+  mesg.msg_iovlen = 2;
+
+  mesg.msg_controllen = cmsg_size ();
+  mesg.msg_control = (char *) malloc (mesg.msg_controllen);
+  check_malloc_return (mesg.msg_control);
+  mesg.msg_flags = 0;
+
+  h = CMSG_FIRSTHDR(&mesg);
+  h->cmsg_len = CMSG_LEN(sizeof(socket_descriptor_t));
+  h->cmsg_level = SOL_SOCKET;
+  h->cmsg_type = SCM_RIGHTS;
+  *((socket_descriptor_t*)CMSG_DATA(h)) = SOCKET_UNDEFINED;
+
+  status = recvmsg (sd_control, &mesg, MSG_NOSIGNAL);
+  if (status != -1)
+    {
+      if (   h == NULL
+	  || h->cmsg_len    != CMSG_LEN(sizeof(socket_descriptor_t))
+	  || h->cmsg_level  != SOL_SOCKET
+	  || h->cmsg_type   != SCM_RIGHTS )
+	{
+	  ret = false;
+	}
+      else
+	{
+	  const socket_descriptor_t received_fd = *((socket_descriptor_t*)CMSG_DATA(h));
+	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED sd=%d", (int)received_fd);
+
+	  if (status >= 2 && command == COMMAND_REDIRECT)
+	    {
+	      buf.len = status - 1;
+	      if (proxy_entry_new (list,
+				   es,
+				   server_addr,
+				   server_port,
+				   received_fd,
+				   &buf))
+		{
+		  CLEAR (buf); /* we gave the buffer to proxy_entry_new */
+		}
+	      else
+		{
+		  openvpn_close_socket (received_fd);
+		}
+	    }
+	  else if (status >= 1 && command == COMMAND_EXIT)
+	    {
+	      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: RECEIVED COMMAND_EXIT");
+	      openvpn_close_socket (received_fd); /* null socket */
+	      ret = false;
+	    }
+	}
+    }
+  free (mesg.msg_control);
+  free_buf (&buf);
+  return ret;
+}
+
+static int
+proxy_connection_io_recv (struct proxy_connection *pc)
+{
+  /* recv data from socket */
+  const int status = recv (pc->sd, BPTR(&pc->buf), BCAP(&pc->buf), MSG_NOSIGNAL);
+  if (status < 0)
+    {
+      return (errno == EAGAIN) ? IOSTAT_EAGAIN_ON_READ : IOSTAT_READ_ERROR;
+    }
+  else
+    {
+      if (!status)
+	return IOSTAT_READ_ERROR;
+      pc->buf.len = status;
+    }
+  return IOSTAT_GOOD;
+}
+
+static int
+proxy_connection_io_send (struct proxy_connection *pc, int *bytes_sent)
+{
+  const socket_descriptor_t sd = pc->counterpart->sd;
+  const int status = send (sd, BPTR(&pc->buf), BLEN(&pc->buf), MSG_NOSIGNAL);
+
+  if (status < 0)
+    {
+      const int e = errno;
+      return (e == EAGAIN) ? IOSTAT_EAGAIN_ON_WRITE : IOSTAT_WRITE_ERROR;
+    }
+  else
+    {
+      *bytes_sent += status;
+      if (status != pc->buf.len)
+	{
+	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: partial write[%d], tried=%d got=%d", (int)sd, pc->buf.len, status);
+	  buf_advance (&pc->buf, status);
+	  return IOSTAT_EAGAIN_ON_WRITE;
+	}
+      else
+	{
+	  /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: wrote[%d] %d", (int)sd, status);*/
+	  pc->buf.len = 0;
+	  pc->buf.offset = 0;
+	}
+    }
+
+  /* realloc send buffer after initial send */
+  if (pc->buffer_initial)
+    {
+      free_buf (&pc->buf);
+      pc->buf = alloc_buf (PROXY_CONNECTION_BUFFER_SIZE);
+      pc->buffer_initial = false;
+    }
+  return IOSTAT_GOOD;
+}
+
+/*
+ * Forward data from pc to pc->counterpart.
+ */
+
+static int
+proxy_connection_io_xfer (struct proxy_connection *pc, const int max_transfer)
+{
+  int transferred = 0;
+  while (transferred < max_transfer)
+    {
+      if (!BLEN (&pc->buf))
+	{
+	  const int status = proxy_connection_io_recv (pc);
+	  if (status != IOSTAT_GOOD)
+	    return status;
+	}
+
+      if (BLEN (&pc->buf))
+	{
+	  const int status = proxy_connection_io_send (pc, &transferred);
+	  if (status != IOSTAT_GOOD)
+	    return status;
+	}
+    }
+  return IOSTAT_EAGAIN_ON_READ;
+}
+
+/*
+ * Decide how the receipt of an EAGAIN status should affect our next IO queueing.
+ */
+static bool
+proxy_connection_io_status (const int status, int *rwflags_pc, int *rwflags_cp)
+{
+  switch (status)
+    {
+    case IOSTAT_EAGAIN_ON_READ:
+      *rwflags_pc |= EVENT_READ;
+      *rwflags_cp &= ~EVENT_WRITE;
+      return true;
+    case IOSTAT_EAGAIN_ON_WRITE:
+      *rwflags_pc &= ~EVENT_READ;
+      *rwflags_cp |= EVENT_WRITE;
+      return true;
+    case IOSTAT_READ_ERROR:
+      return false;
+    case IOSTAT_WRITE_ERROR:
+      return false;
+    default:
+      msg (M_FATAL, "PORT SHARE PROXY: unexpected status=%d", status);
+    }
+  return false; /* NOTREACHED */
+}
+
+/*
+ * Dispatch function for forwarding data between the two socket fds involved
+ * in the proxied connection.
+ */
+static int
+proxy_connection_io_dispatch (struct proxy_connection *pc,
+			      const int rwflags,
+			      struct event_set *es)
+{
+  const int max_transfer_per_iteration = 10000;
+  struct proxy_connection *cp = pc->counterpart;
+  int rwflags_pc = pc->rwflags;
+  int rwflags_cp = cp->rwflags;
+
+  if (rwflags & EVENT_READ)
+    {
+      const int status = proxy_connection_io_xfer (pc, max_transfer_per_iteration);
+      if (!proxy_connection_io_status (status, &rwflags_pc, &rwflags_cp))
+	goto bad;
+    }
+  if (rwflags & EVENT_WRITE)
+    {
+      const int status = proxy_connection_io_xfer (cp, max_transfer_per_iteration);
+      if (!proxy_connection_io_status (status, &rwflags_cp, &rwflags_pc))
+	goto bad;
+    }
+  proxy_connection_io_requeue (pc, rwflags_pc, es);
+  proxy_connection_io_requeue (cp, rwflags_cp, es);
+
+  return true;
+
+ bad:
+  proxy_entry_mark_for_close (pc, es);
+  return false;
+}
+
+/*
+ * This is the main function for the port share proxy background process.
+ */
+static void
+port_share_proxy (const in_addr_t hostaddr, const int port, const socket_descriptor_t sd_control)
+{
+  if (send_control (sd_control, RESPONSE_INIT_SUCCEEDED) >= 0)
+    {
+      void *sd_control_marker = (void *)1;
+      int maxevents = 256;
+      struct event_set *es;
+      struct event_set_return esr[64];
+      struct proxy_connection *list = NULL;
+      time_t last_housekeeping = 0;
+
+      msg (D_PS_PROXY, "PORT SHARE PROXY: proxy starting");
+
+      es = event_set_init (&maxevents, 0);
+      event_ctl (es, sd_control, EVENT_READ, sd_control_marker);
+      while (true)
+	{
+	  int n_events;
+	  struct timeval tv;
+	  time_t current;
+
+	  tv.tv_sec = 10;
+	  tv.tv_usec = 0;
+	  n_events = event_wait (es, &tv, esr, SIZE(esr));
+	  /*dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait returned %d", n_events);*/
+	  current = time(NULL);
+	  if (n_events > 0)
+	    {
+	      int i;
+	      for (i = 0; i < n_events; ++i)
+		{
+		  const struct event_set_return *e = &esr[i];
+		  if (e->arg == sd_control_marker)
+		    {
+		      if (!control_message_from_parent (sd_control, &list, es, hostaddr, port))
+			goto done;
+		    }
+		  else
+		    {
+		      struct proxy_connection *pc = (struct proxy_connection *)e->arg;
+		      if (pc->defined)
+			proxy_connection_io_dispatch (pc, e->rwflags, es);
+		    }
+		}
+	    }
+	  else if (n_events < 0)
+	    {
+	      dmsg (D_PS_PROXY_DEBUG, "PORT SHARE PROXY: event_wait failed");
+	    }
+	  if (current > last_housekeeping)
+	    {
+	      proxy_list_housekeeping (&list);
+	      last_housekeeping = current;
+	    }
+	}
+
+    done:
+      proxy_list_close (&list);
+      event_free (es);
+    }
+  msg (D_PS_PROXY, "PORT SHARE PROXY: proxy exiting");
+}
+
+/*
+ * Called from the main OpenVPN process to enable the port
+ * share proxy.
+ */
+struct port_share *
+port_share_open (const char *host, const int port)
+{
+  pid_t pid;
+  socket_descriptor_t fd[2];
+  in_addr_t hostaddr;
+  struct port_share *ps;
+
+  ALLOC_OBJ_CLEAR (ps, struct port_share);
+
+  /*
+   * Get host's IP address
+   */
+  hostaddr = getaddr (GETADDR_RESOLVE|GETADDR_HOST_ORDER|GETADDR_FATAL, host, 0, NULL, NULL);
+
+  /*
+   * Make a socket for foreground and background processes
+   * to communicate.
+   */
+  if (socketpair (PF_UNIX, SOCK_DGRAM, 0, fd) == -1)
+    {
+      msg (M_WARN, "PORT SHARE: socketpair call failed");
+      goto error;
+    }
+
+  /*
+   * Fork off background proxy process.
+   */
+  pid = fork ();
+
+  if (pid)
+    {
+      int status;
+
+      /*
+       * Foreground Process
+       */
+
+      ps->background_pid = pid;
+
+      /* close our copy of child's socket */
+      openvpn_close_socket (fd[1]);
+
+      /* don't let future subprocesses inherit child socket */
+      set_cloexec (fd[0]);
+
+      /* wait for background child process to initialize */
+      status = recv_control (fd[0]);
+      if (status == RESPONSE_INIT_SUCCEEDED)
+	{
+	  ps->foreground_fd = fd[0];
+	  return ps;
+	}
+    }
+  else
+    {
+      /*
+       * Background Process
+       */
+
+      /* Ignore most signals (the parent will receive them) */
+      set_signals ();
+
+      /* Let msg know that we forked */
+      msg_forked ();
+
+#ifdef ENABLE_MANAGEMENT
+      /* Don't interact with management interface */
+      management = NULL;
+#endif
+
+      /* close all parent fds except our socket back to parent */
+      close_fds_except (fd[1]);
+
+      /* no blocking on control channel back to parent */
+      set_nonblock (fd[1]);
+
+      /* initialize prng */
+      prng_init (NULL, 0);
+
+      /* execute the event loop */
+      port_share_proxy (hostaddr, port, fd[1]);
+
+      openvpn_close_socket (fd[1]);
+
+      exit (0);
+      return 0; /* NOTREACHED */
+    }
+
+ error:
+  port_share_close (ps);
+  return NULL;
+}
+
+void
+port_share_close (struct port_share *ps)
+{
+  if (ps)
+    {
+      if (ps->foreground_fd >= 0)
+	{
+	  /* tell background process to exit */
+	  port_share_sendmsg (ps->foreground_fd, COMMAND_EXIT, NULL, SOCKET_UNDEFINED);
+
+	  /* wait for background process to exit */
+	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: waiting for background process to exit");
+	  if (ps->background_pid > 0)
+	    waitpid (ps->background_pid, NULL, 0);
+	  dmsg (D_PS_PROXY_DEBUG, "PORT SHARE: background process exited");
+
+	  openvpn_close_socket (ps->foreground_fd);
+	  ps->foreground_fd = -1;
+	}
+
+      free (ps);
+    }
+}
+
+void
+port_share_abort (struct port_share *ps)
+{
+  if (ps)
+    {
+      /* tell background process to exit */
+      if (ps->foreground_fd >= 0)
+	{
+	  send_control (ps->foreground_fd, COMMAND_EXIT);
+	  openvpn_close_socket (ps->foreground_fd);
+	  ps->foreground_fd = -1;
+	}
+    }
+}
+
+/*
+ * Given either the first 2 or 3 bytes of an initial client -> server
+ * data payload, return true if the protocol is that of an OpenVPN
+ * client attempting to connect with an OpenVPN server.
+ */
+bool
+is_openvpn_protocol (const struct buffer *buf)
+{
+  const unsigned char *p = (const unsigned char *) BSTR (buf);
+  const int len = BLEN (buf);
+  if (len >= 3)
+    {
+      return p[0] == 0
+	&& p[1] >= 14
+	&& p[2] == (P_CONTROL_HARD_RESET_CLIENT_V2<<P_OPCODE_SHIFT);
+    }
+  else if (len >= 2)
+    {
+      return p[0] == 0 && p[1] >= 14;
+    }
+  else
+    return true;
+}
+
+/*
+ * Called from the foreground process.  Send a message to the background process that it
+ * should proxy the TCP client on sd to the host/port defined in the initial port_share_open
+ * call.
+ */
+void
+port_share_redirect (struct port_share *ps, const struct buffer *head, socket_descriptor_t sd)
+{
+  if (ps)
+    port_share_sendmsg (ps->foreground_fd, COMMAND_REDIRECT, head, sd);
+}
+
+#endif