/*-GNU-GPL-BEGIN-*
nepim - network pipemeter
Copyright (C) 2005 Everton da Silva Marques

nepim 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.

nepim 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 nepim; see the file COPYING.  If not, write to
the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*-GNU-GPL-END-*/


/* $Id: udp_header.c,v 1.7 2005/09/12 23:41:41 evertonm Exp $ */

#include <sys/types.h>
#include <netinet/in.h>
#include <stdio.h>
#include <assert.h>

#include "udp_header.h"

/* 
   version     1
   local_slot  2
   remote_slot 2
   type        1
   seq         4
*/
const int UDP_HEADER_LEN = 1 + 2 + 2 + 1 + 4;

static const int UDP_HDR_OFF_VERSION  = 0;
static const int UDP_HDR_OFF_DST_SLOT = 1;
static const int UDP_HDR_OFF_SRC_SLOT = 3;
static const int UDP_HDR_OFF_TYPE     = 5;
static const int UDP_HDR_OFF_SEQ      = 6;

int nepim_udp_hdr_parse(nepim_udp_hdr_t *hdr, const char *buf, int buf_size)
{
  if (buf_size < UDP_HEADER_LEN)
    return -1;
  
  hdr->version  = buf[UDP_HDR_OFF_VERSION];
  hdr->dst_slot = nepim_uint16_read(buf + UDP_HDR_OFF_DST_SLOT);
  hdr->src_slot = nepim_uint16_read(buf + UDP_HDR_OFF_SRC_SLOT);
  hdr->type     = buf[UDP_HDR_OFF_TYPE];
  hdr->seq      = nepim_uint32_read(buf + UDP_HDR_OFF_SEQ);
  
  return 0;
}

void nepim_udp_hdr_write(const nepim_udp_hdr_t *hdr, char *buf, int buf_size)
{
  assert(buf_size >= UDP_HEADER_LEN);
  
  buf[UDP_HDR_OFF_VERSION] = hdr->version;
  nepim_uint16_write(buf + UDP_HDR_OFF_DST_SLOT, hdr->dst_slot);
  nepim_uint16_write(buf + UDP_HDR_OFF_SRC_SLOT, hdr->src_slot);
  buf[UDP_HDR_OFF_TYPE] = hdr->type;
  nepim_uint32_write(buf + UDP_HDR_OFF_SEQ, hdr->seq);
}