/*
    device.h -- generic header for device.c
    Copyright (C) 2003-2008 Marc Lehmann <gvpe@schmorp.de>
 
    This file is part of GVPE.

    GVPE 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/>.
   
    Additional permission under GNU GPL version 3 section 7
   
    If you modify this Program, or any covered work, by linking or
    combining it with the OpenSSL project's OpenSSL library (or a modified
    version of that library), containing parts covered by the terms of the
    OpenSSL or SSLeay licenses, the licensors of this Program grant you
    additional permission to convey the resulting work.  Corresponding
    Source for a non-source form of such a combination shall include the
    source code for the parts of OpenSSL used as well as that of the
    covered work.
*/

#ifndef GVPE_DEVICE_H__
#define GVPE_DEVICE_H__

#include "config.h"

#define IFNAMESIZE 256 // be conservative

#include "global.h"
#include "util.h"

struct net_packet
{
  u32 len; // actually u16, but padding...
  // upto 4 bytes at the end might get overwritten when decrypting,
  // which means len, above, is regularly overwritten with part
  // of the random prefix when RAND_BYTES=12.

  u8 &operator[] (u16 offset) const;
  u8 *at (u16 offset) const;

  void unshift_hdr (u16 hdrsize)
    {
      memmove ((void *)&(*this)[hdrsize], (void *)&(*this)[0], len);
      len += hdrsize;
    }

  void skip_hdr (u16 hdrsize)
    {
      len -= hdrsize;
      memmove ((void *)&(*this)[0], (void *)&(*this)[hdrsize], len);
    }

  u16 ipv4_hdr_len () const
    {
      return ((*this)[0] & 15) << 2;
    }

  void set (const net_packet &pkt)
    {
      len = pkt.len;
      memcpy (&((*this)[0]), &(pkt[0]), len);
    }

  bool is_ipv4 () const
    {
      return (*this)[12] == 0x08 && (*this)[13] == 0x00 // IP
          && ((*this)[14] & 0xf0) == 0x40;              // IPv4
    }

  u32 &ipv4_src () const
    {
      return *(u32 *)&(*this)[26];
    }
  
  u32 &ipv4_dst () const
    {
      return *(u32 *)&(*this)[30];
    }
  
  bool is_arp () const
    {
      return (*this)[12] == 0x08 && (*this)[13] == 0x06		// 0806 protocol
          && (*this)[14] == 0x00 && (*this)[15] == 0x01		// 0001 hw_format
          && (*this)[16] == 0x08 && (*this)[17] == 0x00		// 0800 prot_format
          && (*this)[18] == 0x06 && (*this)[19] == 0x04;	// 06 hw_len 04 prot_len
    }

  void *operator new (size_t s);
  void operator delete (void *p);
};

struct data_packet : net_packet
{
  u8 data_[MAXSIZE];
};

inline
u8 &net_packet::operator[] (u16 offset) const
{
  return ((data_packet *)this)->data_[offset];
}

inline
u8 *net_packet::at (u16 offset) const
{
  return &((*this)[offset]);
}

struct tap_packet : net_packet
{
  mac dst;
  mac src;
  u8 data[MAXSIZE - 12];
};

struct tap_device
{
  int fd;

  // network interface name or identifier
  char ifrname[IFNAMESIZE + 1];

  char *device;

  tap_device ();
  ~tap_device ();

  //bool open ();
  //void close ();

  const char *interface () { return ifrname; }
  const char *info ();
  const char *if_up ();

  tap_packet *recv ();
  void send (tap_packet *pkt);
};

//extern tap_device *tap_device ();

#endif