/* Serial interface for raw TCP connections on Un*x like systems.

   Copyright (C) 1992, 1993, 1994, 1995, 1996, 1998, 1999, 2001, 2005, 2006,
   2007, 2008, 2009, 2010, 2011 Free Software Foundation, Inc.

   This file is part of GDB.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   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.  If not, see <http://www.gnu.org/licenses/>.  */

#include "defs.h"
#include "serial.h"
#include "ser-base.h"
#include "ser-tcp.h"
#include "gdbcmd.h"
#include "cli/cli-decode.h"
#include "cli/cli-setshow.h"

#include <sys/types.h>

#ifdef HAVE_SYS_FILIO_H
#include <sys/filio.h>  /* For FIONBIO.  */
#endif
#ifdef HAVE_SYS_IOCTL_H
#include <sys/ioctl.h>  /* For FIONBIO.  */
#endif

#include <sys/time.h>

#ifdef USE_WIN32API
#include <winsock2.h>
#define ETIMEDOUT WSAETIMEDOUT
#define close(fd) closesocket (fd)
#define ioctl ioctlsocket
#else
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/socket.h>
#include <netinet/tcp.h>
#endif

#include <signal.h>
#include "gdb_string.h"
#include "gdb_select.h"

#ifndef HAVE_SOCKLEN_T
typedef int socklen_t;
#endif

void _initialize_ser_tcp (void);

/* For "set tcp" and "show tcp".  */

static struct cmd_list_element *tcp_set_cmdlist;
static struct cmd_list_element *tcp_show_cmdlist;

/* Whether to auto-retry refused connections.  */

static int tcp_auto_retry = 1;

/* Timeout period for connections, in seconds.  */

static int tcp_retry_limit = 15;

/* How many times per second to poll deprecated_ui_loop_hook.  */

#define POLL_INTERVAL 5

/* Helper function to wait a while.  If SCB is non-null, wait on its
   file descriptor.  Otherwise just wait on a timeout, updating *POLLS.
   Returns -1 on timeout or interrupt, otherwise the value of select.  */

static int
wait_for_connect (struct serial *scb, int *polls)
{
  struct timeval t;
  int n;

  /* While we wait for the connect to complete, 
     poll the UI so it can update or the user can 
     interrupt.  */
  if (deprecated_ui_loop_hook && deprecated_ui_loop_hook (0))
    {
      errno = EINTR;
      return -1;
    }

  /* Check for timeout.  */
  if (*polls > tcp_retry_limit * POLL_INTERVAL)
    {
      errno = ETIMEDOUT;
      return -1;
    }

  /* Back off to polling once per second after the first POLL_INTERVAL
     polls.  */
  if (*polls < POLL_INTERVAL)
    {
      t.tv_sec = 0;
      t.tv_usec = 1000000 / POLL_INTERVAL;
    }
  else
    {
      t.tv_sec = 1;
      t.tv_usec = 0;
    }

  if (scb)
    {
      fd_set rset, wset, eset;

      FD_ZERO (&rset);
      FD_SET (scb->fd, &rset);
      wset = rset;
      eset = rset;
	  
      /* POSIX systems return connection success or failure by signalling
	 wset.  Windows systems return success in wset and failure in
	 eset.
     
	 We must call select here, rather than gdb_select, because
	 the serial structure has not yet been initialized - the
	 MinGW select wrapper will not know that this FD refers
	 to a socket.  */
      n = select (scb->fd + 1, &rset, &wset, &eset, &t);
    }
  else
    /* Use gdb_select here, since we have no file descriptors, and on
       Windows, plain select doesn't work in that case.  */
    n = gdb_select (0, NULL, NULL, NULL, &t);

  /* If we didn't time out, only count it as one poll.  */
  if (n > 0 || *polls < POLL_INTERVAL)
    (*polls)++;
  else
    (*polls) += POLL_INTERVAL;

  return n;
}

/* Open a tcp socket.  */

int
net_open (struct serial *scb, const char *name)
{
  char *port_str, hostname[100];
  int n, port, tmp;
  int use_udp;
  struct hostent *hostent;
  struct sockaddr_in sockaddr;
#ifdef USE_WIN32API
  u_long ioarg;
#else
  int ioarg;
#endif
  int polls = 0;

  use_udp = 0;
  if (strncmp (name, "udp:", 4) == 0)
    {
      use_udp = 1;
      name = name + 4;
    }
  else if (strncmp (name, "tcp:", 4) == 0)
    name = name + 4;

  port_str = strchr (name, ':');

  if (!port_str)
    error (_("net_open: No colon in host name!"));  /* Shouldn't ever
						       happen.  */

  tmp = min (port_str - name, (int) sizeof hostname - 1);
  strncpy (hostname, name, tmp);	/* Don't want colon.  */
  hostname[tmp] = '\000';	/* Tie off host name.  */
  port = atoi (port_str + 1);

  /* Default hostname is localhost.  */
  if (!hostname[0])
    strcpy (hostname, "localhost");

  hostent = gethostbyname (hostname);
  if (!hostent)
    {
      fprintf_unfiltered (gdb_stderr, "%s: unknown host\n", hostname);
      errno = ENOENT;
      return -1;
    }

  sockaddr.sin_family = PF_INET;
  sockaddr.sin_port = htons (port);
  memcpy (&sockaddr.sin_addr.s_addr, hostent->h_addr,
	  sizeof (struct in_addr));

 retry:

  if (use_udp)
    scb->fd = socket (PF_INET, SOCK_DGRAM, 0);
  else
    scb->fd = socket (PF_INET, SOCK_STREAM, 0);

  if (scb->fd == -1)
    return -1;
  
  /* Set socket nonblocking.  */
  ioarg = 1;
  ioctl (scb->fd, FIONBIO, &ioarg);

  /* Use Non-blocking connect.  connect() will return 0 if connected
     already.  */
  n = connect (scb->fd, (struct sockaddr *) &sockaddr, sizeof (sockaddr));

  if (n < 0)
    {
#ifdef USE_WIN32API
      int err = WSAGetLastError();
#else
      int err = errno;
#endif

      /* Maybe we're waiting for the remote target to become ready to
	 accept connections.  */
      if (tcp_auto_retry
#ifdef USE_WIN32API
	  && err == WSAECONNREFUSED
#else
	  && err == ECONNREFUSED
#endif
	  && wait_for_connect (NULL, &polls) >= 0)
	{
	  close (scb->fd);
	  goto retry;
	}

      if (
#ifdef USE_WIN32API
	  /* Under Windows, calling "connect" with a non-blocking socket
	     results in WSAEWOULDBLOCK, not WSAEINPROGRESS.  */
	  err != WSAEWOULDBLOCK
#else
	  err != EINPROGRESS
#endif
	  )
	{
	  errno = err;
	  net_close (scb);
	  return -1;
	}

      /* Looks like we need to wait for the connect.  */
      do 
	{
	  n = wait_for_connect (scb, &polls);
	} 
      while (n == 0);
      if (n < 0)
	{
	  net_close (scb);
	  return -1;
	}
    }

  /* Got something.  Is it an error?  */
  {
    int res, err;
    socklen_t len;

    len = sizeof (err);
    /* On Windows, the fourth parameter to getsockopt is a "char *";
       on UNIX systems it is generally "void *".  The cast to "void *"
       is OK everywhere, since in C "void *" can be implicitly
       converted to any pointer type.  */
    res = getsockopt (scb->fd, SOL_SOCKET, SO_ERROR, (void *) &err, &len);
    if (res < 0 || err)
      {
	/* Maybe the target still isn't ready to accept the connection.  */
	if (tcp_auto_retry
#ifdef USE_WIN32API
	    && err == WSAECONNREFUSED
#else
	    && err == ECONNREFUSED
#endif
	    && wait_for_connect (NULL, &polls) >= 0)
	  {
	    close (scb->fd);
	    goto retry;
	  }
	if (err)
	  errno = err;
	net_close (scb);
	return -1;
      }
  } 

  /* Turn off nonblocking.  */
  ioarg = 0;
  ioctl (scb->fd, FIONBIO, &ioarg);

  if (use_udp == 0)
    {
      /* Disable Nagle algorithm.  Needed in some cases.  */
      tmp = 1;
      setsockopt (scb->fd, IPPROTO_TCP, TCP_NODELAY,
		  (char *)&tmp, sizeof (tmp));
    }

#ifdef SIGPIPE
  /* If we don't do this, then GDB simply exits
     when the remote side dies.  */
  signal (SIGPIPE, SIG_IGN);
#endif

  return 0;
}

void
net_close (struct serial *scb)
{
  if (scb->fd == -1)
    return;

  close (scb->fd);
  scb->fd = -1;
}

int
net_read_prim (struct serial *scb, size_t count)
{
  return recv (scb->fd, scb->buf, count, 0);
}

int
net_write_prim (struct serial *scb, const void *buf, size_t count)
{
  return send (scb->fd, buf, count, 0);
}

int
ser_tcp_send_break (struct serial *scb)
{
  /* Send telnet IAC and BREAK characters.  */
  return (serial_write (scb, "\377\363", 2));
}

/* Support for "set tcp" and "show tcp" commands.  */

static void
set_tcp_cmd (char *args, int from_tty)
{
  help_list (tcp_set_cmdlist, "set tcp ", -1, gdb_stdout);
}

static void
show_tcp_cmd (char *args, int from_tty)
{
  help_list (tcp_show_cmdlist, "show tcp ", -1, gdb_stdout);
}


void
_initialize_ser_tcp (void)
{
#ifdef USE_WIN32API
  /* Do nothing; the TCP serial operations will be initialized in
     ser-mingw.c.  */
#else
  struct serial_ops *ops;

  ops = XMALLOC (struct serial_ops);
  memset (ops, 0, sizeof (struct serial_ops));
  ops->name = "tcp";
  ops->next = 0;
  ops->open = net_open;
  ops->close = net_close;
  ops->readchar = ser_base_readchar;
  ops->write = ser_base_write;
  ops->flush_output = ser_base_flush_output;
  ops->flush_input = ser_base_flush_input;
  ops->send_break = ser_tcp_send_break;
  ops->go_raw = ser_base_raw;
  ops->get_tty_state = ser_base_get_tty_state;
  ops->copy_tty_state = ser_base_copy_tty_state;
  ops->set_tty_state = ser_base_set_tty_state;
  ops->print_tty_state = ser_base_print_tty_state;
  ops->noflush_set_tty_state = ser_base_noflush_set_tty_state;
  ops->setbaudrate = ser_base_setbaudrate;
  ops->setstopbits = ser_base_setstopbits;
  ops->drain_output = ser_base_drain_output;
  ops->async = ser_base_async;
  ops->read_prim = net_read_prim;
  ops->write_prim = net_write_prim;
  serial_add_interface (ops);
#endif /* USE_WIN32API */

  add_prefix_cmd ("tcp", class_maintenance, set_tcp_cmd, _("\
TCP protocol specific variables\n\
Configure variables specific to remote TCP connections"),
		  &tcp_set_cmdlist, "set tcp ",
		  0 /* allow-unknown */, &setlist);
  add_prefix_cmd ("tcp", class_maintenance, show_tcp_cmd, _("\
TCP protocol specific variables\n\
Configure variables specific to remote TCP connections"),
		  &tcp_show_cmdlist, "show tcp ",
		  0 /* allow-unknown */, &showlist);

  add_setshow_boolean_cmd ("auto-retry", class_obscure,
			   &tcp_auto_retry, _("\
Set auto-retry on socket connect"), _("\
Show auto-retry on socket connect"), 
			   NULL, NULL, NULL,
			   &tcp_set_cmdlist, &tcp_show_cmdlist);

  add_setshow_uinteger_cmd ("connect-timeout", class_obscure,
			    &tcp_retry_limit, _("\
Set timeout limit for socket connection"), _("\
Show timeout limit for socket connection"),
			   NULL, NULL, NULL,
			   &tcp_set_cmdlist, &tcp_show_cmdlist);
}