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/* tcp.c -- Definition of functions for peripheral to

 * communicate with host via a tcp socket.

   Copyright (C) 2002 Richard Prescott <rip@step.polymtl.ca>

   Copyright (C) 2008 Embecosm Limited

   Contributor Jeremy Bennett <jeremy.bennett@embecosm.com>

   This file is part of Or1ksim, the OpenRISC 1000 Architectural Simulator.

   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/>.  */

/* This program is commented throughout in a fashion suitable for processing

   with Doxygen. */

/* Autoconf and/or portability configuration */

#include "config.h"

#include "port.h"

/* System includes */

#include <stdlib.h>

#include <unistd.h>

#include <stdio.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

#include <fcntl.h>

#include <errno.h>

/* Package includes */

#include "channel.h"

#include "generic.h"

#include "fd.h"

/*! Structure to represent a TCP/IP channel */

struct tcp_channel

{

  struct fd_channel fds;

  int               socket_fd;    /* Socket to listen to */

  int               port_number;  /* TCP port number */

  int               connected;    /* If 0, no remote endpoint yet */

  int               nonblocking;  /* If 0, read/write will block until

                                     remote client connects */

};

/* Forward declarations of static functions */

static void *tcp_init (const char *input);

static int   tcp_open (void *data);

static int   tcp_read (void *data,

                       char *buffer,

                       int   size);

static int   tcp_write (void       *data,

                        const char *buffer,

                        int         size);

/*! Data structure holding all the operations for a TCP/IP channel */

struct channel_ops  tcp_channel_ops = {

        .init  = tcp_init,

        .open  = tcp_open,

        .close = generic_close,

        .read  = tcp_read,

        .write = tcp_write,

        .free  = generic_free,

};

static void *

tcp_init (const char *input)

{

  int port_number, fd, flags;

  struct sockaddr_in local_ip;

  struct tcp_channel *channel =

    (struct tcp_channel *) malloc (sizeof (struct tcp_channel));

  if (!channel)

    return NULL;

  fd = 0;

  channel->nonblocking = 1;

  channel->fds.fdin = -1;

  channel->fds.fdout = -1;

  channel->socket_fd = -1;

  channel->port_number = -1;

  port_number = atoi (input);

  if (port_number == 0)

    goto error;

  fd = socket (AF_INET, SOCK_STREAM, 0);

  if (fd < 0)

    goto error;

  flags = 1;

  if (setsockopt

      (fd, SOL_SOCKET, SO_REUSEADDR, (const char *) &flags, sizeof (int)) < 0)

    {

      perror ("Can not set SO_REUSEADDR option on channel socket");

      goto error;

    }

  memset (&local_ip, 0, sizeof (local_ip));

  local_ip.sin_family = AF_INET;

  local_ip.sin_addr.s_addr = htonl (INADDR_ANY);

  local_ip.sin_port = htons (port_number);

  if (bind (fd, (struct sockaddr *) &local_ip, sizeof (local_ip)) < 0)

    {

      perror ("Can't bind local address");

      goto error;

    }

  if (channel->nonblocking)

    {

      if (fcntl (fd, F_SETFL, O_NONBLOCK) < 0)

        {

          perror ("Can not make channel socket non-blocking");

          goto error;

        }

    }

  if (listen (fd, 1) < 0)

    goto error;

  channel->socket_fd = fd;

  channel->port_number = port_number;

  channel->connected = 0;

  return (void *) channel;

error:

  if (fd)

    close (fd);

  free (channel);

  return NULL;

}

static int

tcp_open (void *data)

{

  /* Socket is opened lazily, upon first read or write, so do nothing here */

  return 0;

}

static int

wait_for_tcp_connect (struct tcp_channel *channel)

{

  int fd;

  socklen_t sizeof_remote_ip;

  struct sockaddr_in remote_ip;

  sizeof_remote_ip = sizeof (remote_ip);

  fd =

    accept (channel->socket_fd, (struct sockaddr *) &remote_ip,

            &sizeof_remote_ip);

  if (fd < 0)

    {

      if (channel->nonblocking)

        {

          /* Not an error if there is not yet a remote connection - try again later */

          if (errno == EAGAIN)

            return 0;

        }

      perror ("Couldn't accept connection");

      return -1;

    }

  channel->fds.fdin = channel->fds.fdout = fd;

  close (channel->socket_fd);

  channel->socket_fd = -1;

  channel->connected = 1;

  return 1;

}

static int

tcp_read (void *data, char *buffer, int size)

{

  struct tcp_channel *channel = data;

  /* Lazily connect to tcp partner on read/write */

  if (!channel->connected)

    {

      int retval = wait_for_tcp_connect (data);

      if (retval <= 0)

        return retval;

    }

  return fd_read (data, buffer, size);

}

static int

tcp_write (void *data, const char *buffer, int size)

{

  struct tcp_channel *channel = data;

  /* Lazily connect to tcp partner on read/write */

  if (!channel->connected)

    {

      int retval = wait_for_tcp_connect (data);

      if (retval < 0)

        return retval;

    }

  return fd_write (data, buffer, size);

}