/*
 * file net_dgram.c - Datagrams for in game messages
 *
 * $Id: net_dgram.c,v 1.5 2004/05/14 10:00:35 alfie Exp $
 *
 * Program XBLAST 
 * (C) by Oliver Vogel (e-mail: m.vogel@ndh.net)
 *
 * 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; or (at your option)
 * any later version
 *
 * This program is distributed in the hope that it will be entertaining,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of 
 * MERCHANTABILTY 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.
 * 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
#include "net_dgram.h"

/*
 * local structures
 */
struct _xb_datagram {
  void   *data;
  size_t  len;
};

/*
 * local const
 */
#define DGRAM_START    0x68
#define DGRAM_STOP     0x16


/*
 * local variables
 */
static unsigned char buffer[MAX_DGRAM_SIZE+3];

/*
 * create datagram
 */
XBDatagram *
Net_CreateDatagram (const void *data, size_t len)
{
  XBDatagram *ptr;

  assert (len <= MAX_DGRAM_SIZE);
  /* alloc data */
  ptr = calloc (1, sizeof (*ptr));
  assert (NULL != ptr);
  /* alloc buffer */
  ptr->data = calloc (len + 1, 1);
  assert (NULL != ptr->data);
  /* set values */
  ptr->len = len;
  if (NULL != data) {
    memcpy (ptr->data, data, len);
  }
  /* that's all */
  return ptr;
} /* Net_CreateDatagram */

/*
 * delete datagram 
 */
void
Net_DeleteDatagram (XBDatagram *ptr)
{
  assert (ptr != NULL);
  assert (ptr->data != NULL);
  free (ptr->data);
  free (ptr);
} /* Net_DeleteDatagram */

/*
 * write datagramm to buffer
 */
static void
MakeDatagram (const XBDatagram *ptr)
{
  assert (ptr != NULL);
  /* write buffer */
  buffer[0] = DGRAM_START;
  buffer[1] = ptr->len;
  memcpy (buffer + 2, ptr->data, ptr->len);
  buffer[ptr->len+2] = DGRAM_STOP;
  /* send it */
#ifdef DEBUG_TELE
  {
    int i;
    Dbg_Out ("snd dgram ");
    for (i = 0; i < ptr->len; i ++) {
      Dbg_Out ("%02x ", (unsigned) (buffer[i+2]) );
    }
    Dbg_Out ("(%u bytes)\n", ptr->len);
  }
#endif
} /* MakeDatagram */

/*
 * send datagram
 */
XBBool
Net_SendDatagram (const XBDatagram *ptr, const XBSocket *pSocket)
{
  int result;

  MakeDatagram (ptr);
#ifdef DEBUG_UDP
  /* simulate heavy data loss */
  if (rand () % 2) {
    Dbg_Out ("dgram not written\n");
    return XBTrue;
  }
#endif
  
  result = Socket_Send (pSocket, buffer, ptr->len + 3);
  switch (result) {
  case XB_SOCKET_END_OF_FILE:
  case XB_SOCKET_ERROR:
    return XBFalse;
  case XB_SOCKET_WOULD_BLOCK:
    return XBTrue;
  default:
    return (ptr->len + 3 == result);
  }
} /* Net_SendDatagram */

/*
 * send datagram
 */
XBBool
Net_SendDatagramTo (const XBDatagram *ptr, XBSocket *pSocket, const char *host, unsigned short port, XBBool broadcast)
{
  int result;

  MakeDatagram (ptr);

  /* enable broadcast if needed */
  if (broadcast) {
    Socket_SetBroadcast (pSocket, broadcast);
  }
  result = Socket_SendTo (pSocket, buffer, ptr->len + 3, host, port);
  switch (result) {
  case XB_SOCKET_END_OF_FILE:
  case XB_SOCKET_ERROR:
    return XBFalse;
  case XB_SOCKET_WOULD_BLOCK:
    return XBTrue;
  default:
    return (ptr->len + 3 == result);
  }
} /* Net_SendDatagram */

/*
 * parse datagramm in read buffer
 */
static XBDatagram *
ParseDatagram (size_t len)
{
  switch (len) {
  case XB_SOCKET_END_OF_FILE:
  case XB_SOCKET_WOULD_BLOCK:
  case XB_SOCKET_ERROR:
    return NULL;
  }
  /* length check */
  if (len < 3) {
    return NULL;
  }
  /* check start */
  if (buffer[0] != DGRAM_START) {
    return NULL;
  }
  /* check length stop */
  if (buffer[1] + 3 != len) {
    return NULL;
  }
  /* check stop */
  if (buffer[len-1] != DGRAM_STOP) {
    return NULL;
  }
#ifdef DEBUG_TELE
  {
    size_t i;
    Dbg_Out ("rcv dgram ");
    for (i = 0; i < buffer[1]; i ++) {
      Dbg_Out ("%02x ", (unsigned) buffer[i+2]);
    }
    Dbg_Out ("(%u bytes)\n", (unsigned) buffer[1]);
  }
#endif
  /* datagram is correct */
  return Net_CreateDatagram (buffer + 2, buffer[1]);
} /* ParseDatagram */

/*
 * receive datagram
 */
XBDatagram *
Net_ReceiveDatagram (const XBSocket *pSocket)
{
#ifdef W32
  long len;
#else
  ssize_t len;
#endif

  len = Socket_Receive (pSocket, buffer, sizeof (buffer) );
  return ParseDatagram (len);
} /* Net_ReceiveDatagram */

/*
 * receive datagram
 */
XBDatagram *
Net_ReceiveDatagramFrom (XBSocket *pSocket, const char **host, unsigned short *port)
{
#ifdef W32
  long len;
#else
  ssize_t len;
#endif
  len = Socket_ReceiveFrom (pSocket, buffer, sizeof (buffer), host, port);
  return ParseDatagram (len);
} /* Net_ReceiveDatagram */

/*
 * contents of datagram
 */
const void *
Net_DgramData (const XBDatagram *dgram, size_t *len)
{
  assert (NULL != dgram);
  assert (NULL != len);

  *len = dgram->len;
  return dgram->data;
} /* Net_DgramData* */

/*
 * end of file net_dgram.c
 */