/*
 *  anytun
 *
 *  The secure anycast tunneling protocol (satp) defines a protocol used
 *  for communication between any combination of unicast and anycast
 *  tunnel endpoints.  It has less protocol overhead than IPSec in Tunnel
 *  mode and allows tunneling of every ETHER TYPE protocol (e.g.
 *  ethernet, ip, arp ...). satp directly includes cryptography and
 *  message authentication based on the methods used by SRTP.  It is
 *  intended to deliver a generic, scaleable and secure solution for
 *  tunneling and relaying of packets of any protocol.
 *
 *
 *  Copyright (C) 2007-2009 Othmar Gsenger, Erwin Nindl,
 *                          Christian Pointner <satp@wirdorange.org>
 *
 *  This file is part of Anytun.
 *
 *  Anytun 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
 *  any later version.
 *
 *  Anytun 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 anytun.  If not, see <http://www.gnu.org/licenses/>.
 */
#ifndef ANYTUN_cipher_h_INCLUDED
#define ANYTUN_cipher_h_INCLUDED

#include "datatypes.h"
#include "buffer.h"
#include "encryptedPacket.h"
#include "plainPacket.h"
#include "keyDerivation.h"

#ifndef NO_CRYPT

#if defined(USE_SSL_CRYPTO)
#include <openssl/aes.h>
#elif defined(USE_NETTLE)
#include <nettle/aes.h>
#else  // USE_GCRYPT is the default
#include <gcrypt.h>
#endif

#endif

class Cipher
{
public:
  Cipher() : dir_(KD_INBOUND) {};
  Cipher(kd_dir_t d) : dir_(d) {};
  virtual ~Cipher() {};

  void encrypt(KeyDerivation& kd, PlainPacket& in, EncryptedPacket& out, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);
  void decrypt(KeyDerivation& kd, EncryptedPacket& in, PlainPacket& out);

protected:
  virtual uint32_t cipher(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux) = 0;
  virtual uint32_t decipher(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux) = 0;

  kd_dir_t dir_;
};

//****** NullCipher ******

class NullCipher : public Cipher
{
protected:
  uint32_t cipher(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);
  uint32_t decipher(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);
};

#ifndef NO_CRYPT
//****** AesIcmCipher ******

class AesIcmCipher : public Cipher
{
public:
  AesIcmCipher(kd_dir_t d);
  AesIcmCipher(kd_dir_t d, uint16_t key_length);
  ~AesIcmCipher();

  static const uint16_t DEFAULT_KEY_LENGTH = 128;
  static const uint16_t CTR_LENGTH = 16;
  static const uint16_t SALT_LENGTH = 14;

protected:
  uint32_t cipher(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);
  uint32_t decipher(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);

private:
  void init(uint16_t key_length = DEFAULT_KEY_LENGTH);

  void calcCtr(KeyDerivation& kd, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);
  void calc(KeyDerivation& kd, uint8_t* in, uint32_t ilen, uint8_t* out, uint32_t olen, seq_nr_t seq_nr, sender_id_t sender_id, mux_t mux);

#if defined(USE_SSL_CRYPTO)
  AES_KEY aes_key_;
  uint8_t ecount_buf_[AES_BLOCK_SIZE];
#elif defined(USE_NETTLE)
  struct aes_ctx ctx_;
#else  // USE_GCRYPT is the default
  gcry_cipher_hd_t handle_;
#endif

  Buffer key_;
  Buffer salt_;

#ifdef _MSC_VER
#pragma pack(push, 1)
#endif
  union ATTR_PACKED cipher_aesctr_ctr_union {
    uint8_t buf_[CTR_LENGTH];
    struct ATTR_PACKED {
      uint8_t buf_[SALT_LENGTH];
      uint16_t zero_;
    } salt_;
    struct ATTR_PACKED {
      uint8_t fill_[SALT_LENGTH - sizeof(mux_t) - sizeof(sender_id_t) - 2*sizeof(uint8_t) - sizeof(seq_nr_t)];
      mux_t mux_;
      sender_id_t sender_id_;
      uint8_t empty_[2];
      seq_nr_t seq_nr_;
      uint16_t zero_;
    } params_;
  } ctr_;
#ifdef _MSC_VER
#pragma pack(pop)
#endif
};
#endif

#endif