/*
    CrossFire, A Multiplayer game for X-windows

    Copyright (C) 1992 Frank Tore Johansen

    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 2 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, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    The author can be reached via e-mail to mark@pyramid.com
*/

/**
 * \file
 * Low-level socket-related functions.
 *
 * \date 2003-12-02
 *
 * Contains some base functions that both the client and server
 * can use.  As such, depending what we are being compiled for will
 * determine what we can include.  the client is designed have
 * CFCLIENT defined as part of its compile flags.
 */

using namespace std;

#include <global.h>
#include <newclient.h>
#include <sproto.h>

#ifdef __linux__
# include <sys/types.h>
# include <sys/socket.h>
# include <netinet/in.h>
# define TCP_HZ 1000            // sorry...
# include <netinet/tcp.h>
#endif

// use a really low timeout, as it doesn't cost any bandwidth, and you can
// easily die in 20 seconds...
#define SOCKET_TIMEOUT1 10
#define SOCKET_TIMEOUT2 20

void
Socket_Flush (NewSocket * ns)
{
#ifdef __linux__
  // check time of last ack, and, if too old, kill connection
  struct tcp_info tcpi;
  socklen_t len = sizeof (tcpi);

  if (!getsockopt (ns->fd, IPPROTO_TCP, TCP_INFO, &tcpi, &len) && len == sizeof (tcpi))
    {
      unsigned int diff = tcpi.tcpi_last_ack_recv - tcpi.tcpi_last_data_sent;

      if (tcpi.tcpi_unacked && SOCKET_TIMEOUT1 * TCP_HZ < diff && diff < 0x80000000UL   // ack delayed for 20s
          && SOCKET_TIMEOUT2 * TCP_HZ < tcpi.tcpi_last_data_sent)       // no data sent for 10s
        {
          LOG (llevDebug, "Connection on fd %d closed due to ack timeout (%u/%u/%u)\n", ns->fd,
               (unsigned) tcpi.tcpi_last_ack_recv, (unsigned) tcpi.tcpi_last_data_sent, (unsigned) tcpi.tcpi_unacked);
          ns->status = Ns_Dead;
        }
    }

  int val;

  val = 0;
  setsockopt (ns->fd, IPPROTO_TCP, TCP_CORK, &val, sizeof (val));
  val = 1;
  setsockopt (ns->fd, IPPROTO_TCP, TCP_CORK, &val, sizeof (val));
#endif
}

/***********************************************************************
 *
 * SockList functions/utilities
 *
 **********************************************************************/

void
SockList_Init (SockList * sl)
{
  sl->len = 0;
  sl->buf = NULL;
}

void
SockList_AddInt (SockList * sl, uint32 data)
{
  sl->buf[sl->len++] = (data >> 24) & 0xff;
  sl->buf[sl->len++] = (data >> 16) & 0xff;
  sl->buf[sl->len++] = (data >> 8) & 0xff;
  sl->buf[sl->len++] = data & 0xff;
}

void
SockList_AddInt64 (SockList * sl, uint64 data)
{
  sl->buf[sl->len++] = (char) ((data >> 56) & 0xff);
  sl->buf[sl->len++] = (char) ((data >> 48) & 0xff);
  sl->buf[sl->len++] = (char) ((data >> 40) & 0xff);
  sl->buf[sl->len++] = (char) ((data >> 32) & 0xff);

  sl->buf[sl->len++] = (char) ((data >> 24) & 0xff);
  sl->buf[sl->len++] = (char) ((data >> 16) & 0xff);
  sl->buf[sl->len++] = (char) ((data >> 8) & 0xff);
  sl->buf[sl->len++] = (char) (data & 0xff);
}

/* Basically does the reverse of SockList_AddInt, but on
 * strings instead.  Same for the GetShort, but for 16 bits.
 */
int
GetInt_String (unsigned char *data)
{
  return ((data[0] << 24) + (data[1] << 16) + (data[2] << 8) + data[3]);
}

short
GetShort_String (unsigned char *data)
{
  return ((data[0] << 8) + data[1]);
}

/******************************************************************************
 *
 * Start of read routines.
 *
 ******************************************************************************/

/**
 * This reads from fd and puts the data in sl.  We return true if we think
 * we have a full packet, 0 if we have a partial packet.  The only processing
 * we do is remove the intial size value.  len (As passed) is the size of the
 * buffer allocated in the socklist.  We make the assumption the buffer is
 * at least 2 bytes long.
 */

int
SockList_ReadPacket (int fd, SockList * sl, int len)
{
  int stat, toread;

  /* Sanity check - shouldn't happen */
  if (sl->len < 0)
    {
      abort ();
    }
  /* We already have a partial packet */
  if (sl->len < 2)
    {
      do
        {
          stat = read (fd, sl->buf + sl->len, 2 - sl->len);
        }
      while ((stat == -1) && (errno == EINTR));

      if (stat < 0)
        {
          /* In non blocking mode, EAGAIN is set when there is no
           * data available.
           */
          if (errno != EAGAIN && errno != EWOULDBLOCK)
            {
              LOG (llevDebug, "ReadPacket got error %s, returning 0\n", strerror (errno));
            }
          return 0;             /*Error */
        }
      if (stat == 0)
        return -1;
      sl->len += stat;
#ifdef CS_LOGSTATS
      cst_tot.ibytes += stat;
      cst_lst.ibytes += stat;
#endif
      if (stat < 2)
        return 0;               /* Still don't have a full packet */
    }
  /* Figure out how much more data we need to read.  Add 2 from the
   * end of this - size header information is not included.
   */
  toread = 2 + (sl->buf[0] << 8) + sl->buf[1] - sl->len;
  if ((toread + sl->len) >= len)
    {
      LOG (llevError, "SockList_ReadPacket: Want to read more bytes than will fit in buffer (%d>=%d).\n", toread + sl->len, len);
      /* Quick hack in case for 'oldsocketmode' input.  If we are
       * closing the socket anyways, then reading this extra 100 bytes
       * shouldn't hurt.
       */
      read (fd, sl->buf + 2, 100);

      /* return error so the socket is closed */
      return -1;
    }
  do
    {
      do
        {
          stat = read (fd, sl->buf + sl->len, toread);
        }
      while ((stat < 0) && (errno == EINTR));
      if (stat < 0)
        {

          if (errno != EAGAIN && errno != EWOULDBLOCK)
            {
              LOG (llevDebug, "ReadPacket got error %s, returning 0\n", strerror (errno));
            }
          return 0;             /*Error */
        }
      if (stat == 0)
        return -1;
      sl->len += stat;
#ifdef CS_LOGSTATS
      cst_tot.ibytes += stat;
      cst_lst.ibytes += stat;
#endif
      toread -= stat;
      if (toread == 0)
        return 1;
      if (toread < 0)
        {
          LOG (llevError, "SockList_ReadPacket: Read more bytes than desired.\n");
          return 1;
        }
    }
  while (toread > 0);
  return 0;
}

/*******************************************************************************
 *
 * Start of write related routines.
 *
 ******************************************************************************/

/**
 * Adds data to a socket buffer for whatever reason.
 *
 * ns is the socket we are adding the data to, buf is the start of the
 * data, and len is the number of bytes to add.
 */

static void
add_to_buffer (NewSocket * ns, char *buf, int len)
{
  int avail, end;

  if ((len + ns->outputbuffer.len) > SOCKETBUFSIZE)
    {
      LOG (llevDebug, "Socket on fd %d has overrun internal buffer - marking as dead\n", ns->fd);
      ns->status = Ns_Dead;
      return;
    }

  /* data + end is where we start putting the new data.  The last byte
   * currently in use is actually data + end -1
   */

  end = ns->outputbuffer.start + ns->outputbuffer.len;
  /* The buffer is already in a wrapped state, so adjust end */
  if (end >= SOCKETBUFSIZE)
    end -= SOCKETBUFSIZE;

  avail = SOCKETBUFSIZE - end;

  /* We can all fit it behind the current data without wrapping */
  if (avail >= len)
    memcpy (ns->outputbuffer.data + end, buf, len);
  else
    {
      memcpy (ns->outputbuffer.data + end, buf, avail);
      memcpy (ns->outputbuffer.data, buf + avail, len - avail);
    }

  ns->outputbuffer.len += len;
#if 0
  LOG (llevDebug, "Added %d to output buffer, total length now %d, start=%d\n", len, ns->outputbuffer.len, ns->outputbuffer.start);
#endif
}

/**
 * Writes data to socket.
 *
 * When the socket is clear to write, and we have backlogged data, this
 * is called to write it out.
 */
void
write_socket_buffer (NewSocket * ns)
{
  int amt, max;

  if (ns->outputbuffer.len == 0)
    {
      LOG (llevDebug, "write_socket_buffer called when there is no data, fd=%d\n", ns->fd);
      return;
    }

  do
    {
      max = SOCKETBUFSIZE - ns->outputbuffer.start;
      if (ns->outputbuffer.len < max)
        max = ns->outputbuffer.len;

      do
        {
          amt = write (ns->fd, ns->outputbuffer.data + ns->outputbuffer.start, max);
        }
      while ((amt < 0) && (errno == EINTR));

      if (amt < 0)
        {                       /* We got an error */

          if (errno != EWOULDBLOCK)
            {
              LOG (llevError, "New socket write failed (wsb) (%d: %s).\n", errno, strerror (errno));
              ns->status = Ns_Dead;
              return;
            }
          else
            {                   /* EWOULDBLOCK */
              /* can't write it, so store it away. */
              ns->can_write = 0;
              return;
            }
        }
      ns->outputbuffer.start += amt;
      /* wrap back to start of buffer */
      if (ns->outputbuffer.start == SOCKETBUFSIZE)
        ns->outputbuffer.start = 0;
      ns->outputbuffer.len -= amt;
#ifdef CS_LOGSTATS
      cst_tot.obytes += amt;
      cst_lst.obytes += amt;
#endif
    }
  while (ns->outputbuffer.len > 0);
}

/**
 * This writes data to the socket. - It is very low level -
 * all we try and do is write out the data to the socket
 * provided (ns).  buf is the data to write, len is the number
 * of bytes to write.  IT doesn't return anything - rather, it
 * updates the ns structure if we get an  error.
 */
void
Write_To_Socket (NewSocket * ns, char *buf, int len)
{
  int amt = 0;
  char *pos = buf;

  if (ns->status == Ns_Dead || !buf)
    {
      LOG (llevDebug, "Write_To_Socket called with dead socket\n");
      return;
    }

#ifndef __GNU__                 /* This caused problems on Hurd */
  if (!ns->can_write)
    {
      add_to_buffer (ns, buf, len);
      return;
    }
#endif
  /* If we manage to write more than we wanted, take it as a bonus */
  while (len > 0)
    {

      do
        {
          amt = write (ns->fd, pos, len);
        }
      while ((amt < 0) && (errno == EINTR));

      if (amt < 0)
        {                       /* We got an error */
          if (errno != EWOULDBLOCK)
            {
              LOG (llevError, "New socket write failed WTS (%d: %s).\n",        /* ---WIN32 */
                   errno, strerror (errno));
              ns->status = Ns_Dead;
              return;
            }
          else
            {                   /* EWOULDBLOCK */
              /* can't write it, so store it away. */
              add_to_buffer (ns, pos, len);
              ns->can_write = 0;
              return;
            }
        }
      /* amt gets set to 0 above in blocking code, so we do this as
       * an else if to make sure we don't reprocess it.
       */
      else if (amt == 0)
        {
          LOG (llevError, "Write_To_Socket: No data written out.\n");
        }
      len -= amt;
      pos += amt;
#ifdef CS_LOGSTATS
      cst_tot.obytes += amt;
      cst_lst.obytes += amt;
#endif
    }
}


/**
 * Takes a string of data, and writes it out to the socket. A very handy
 * shortcut function.
 */
void
cs_write_string (NewSocket * ns, const char *buf, int len)
{
  SockList sl;

  sl.len = len;
  sl.buf = (unsigned char *) buf;
  Send_With_Handling (ns, &sl);
}


/**
 * Calls Write_To_Socket to send data to the client.
 *
 * The only difference in this function is that we take a SockList
 *, and we prepend the length information.
 */
void
Send_With_Handling (NewSocket * ns, SockList * msg)
{
  unsigned char sbuf[4];

  if (ns->status == Ns_Dead || !msg)
    return;

  if (msg->len >= MAXSOCKBUF)
    {
      LOG (llevError, "Trying to send a buffer beyond properly size, len =%d\n", msg->len);
      /* Almost certainly we've overflowed a buffer, so quite now to make
       * it easier to debug.
       */
      abort ();
    }
  sbuf[0] = ((uint32) (msg->len) >> 8) & 0xFF;
  sbuf[1] = ((uint32) (msg->len)) & 0xFF;
  if (ns->status != Ns_Old)
    Write_To_Socket (ns, (char *) sbuf, 2);
  Write_To_Socket (ns, (char *) msg->buf, msg->len);
}

/**
 * Takes a string of data, and writes it out to the socket. A very handy
 * shortcut function.
 */
void
Write_String_To_Socket (NewSocket * ns, char *buf, int len)
{
  SockList sl;

  sl.len = len;
  sl.buf = (unsigned char *) buf;
  Send_With_Handling (ns, &sl);
}


/******************************************************************************
 *
 * statistics logging functions.
 *
 ******************************************************************************/

#ifdef CS_LOGSTATS

/* cst_tot is for the life of the server, cst_last is for the last series of
 * stats
 */
CS_Stats cst_tot, cst_lst;

/**
 * Writes out the gathered stats.  We clear cst_lst.
 */
void
write_cs_stats (void)
{
  time_t now = time (NULL);

  /* If no connections recently, don't both to log anything */
  if (cst_lst.ibytes == 0 && cst_lst.obytes == 0)
    return;

  /* CSSTAT is put in so scripts can easily find the line */
  LOG (llevInfo, "CSSTAT: %.16s tot %d %d %d %d inc %d %d %d %d\n",
       ctime (&now), cst_tot.ibytes, cst_tot.obytes, cst_tot.max_conn,
       now - cst_tot.time_start, cst_lst.ibytes, cst_lst.obytes, cst_lst.max_conn, now - cst_lst.time_start);
  cst_lst.ibytes = 0;
  cst_lst.obytes = 0;
  cst_lst.max_conn = socket_info.nconns;
  cst_lst.time_start = now;
}
#endif