/*
 *  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 methodes 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) 2007-2008 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 version 3 as
 *  published by the Free Software Foundation.
 *
 *  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/>.
 */


#include "log.h"
#include "keyDerivation.h"
#include "threadUtils.hpp"
#include "datatypes.h"
#include "endian.h"

#include <stdexcept>
#include <iostream>
#include <sstream>
#include <string>

void KeyDerivation::setLogKDRate(const int8_t log_rate)
{
  WritersLock lock(mutex_);
  ld_kdr_ = log_rate;
  if(ld_kdr_ > (int8_t)(sizeof(seq_nr_t) * 8))
    ld_kdr_ = sizeof(seq_nr_t) * 8;
}

//****** NullKeyDerivation ******

bool NullKeyDerivation::generate(kd_dir dir, satp_prf_label label, seq_nr_t seq_nr, Buffer& key)
{
  std::memset(key.getBuf(), 0, key.getLength());
  return true;
}

#ifndef NOCRYPT
//****** AesIcmKeyDerivation ******

AesIcmKeyDerivation::AesIcmKeyDerivation() : KeyDerivation(DEFAULT_KEY_LENGTH) 
{
#ifndef USE_SSL_CRYPTO
  handle_ = NULL;
#endif
}

AesIcmKeyDerivation::AesIcmKeyDerivation(u_int16_t key_length) : KeyDerivation(key_length) 
{
#ifndef USE_SSL_CRYPTO
  handle_ = NULL;
#endif
}

AesIcmKeyDerivation::~AesIcmKeyDerivation()
{
  WritersLock lock(mutex_);
#ifndef USE_SSL_CRYPTO
  if(handle_)
    gcry_cipher_close(handle_);
#endif
}

void AesIcmKeyDerivation::init(Buffer key, Buffer salt)
{
  WritersLock lock(mutex_);

  master_salt_ = SyncBuffer(salt);
  master_key_ = SyncBuffer(key);

  updateMasterKey();
}

void AesIcmKeyDerivation::updateMasterKey()
{
  if(master_key_.getLength()*8 != key_length_) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_CRIT) << "KeyDerivation::updateMasterKey: key lengths don't match";
    return;
  }

  if(master_salt_.getLength() != SALT_LENGTH) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_CRIT) << "KeyDerivation::updateMasterKey: salt lengths don't match";
    return;
  }

#ifndef USE_SSL_CRYPTO
  int algo;
  switch(key_length_) {
  case 128: algo = GCRY_CIPHER_AES128; break;
  case 192: algo = GCRY_CIPHER_AES192; break;
  case 256: algo = GCRY_CIPHER_AES256; break;
  default: {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_CRIT) << "KeyDerivation::updateMasterKey: cipher key length of " << key_length_ << " Bits is not supported";
    return;
  }
  }

  if(handle_)
    gcry_cipher_close(handle_);

  gcry_error_t err = gcry_cipher_open(&handle_, algo, GCRY_CIPHER_MODE_CTR, 0);
  if(err) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::updateMasterKey: Failed to open cipher: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
    return;
  } 

  err = gcry_cipher_setkey(handle_, master_key_.getBuf(), master_key_.getLength());
  if(err) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::updateMasterKey: Failed to set cipher key: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
    return;
  }
#else
  int ret = AES_set_encrypt_key(master_key_.getBuf(), master_key_.getLength()*8, &aes_key_);
  if(ret) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::updateMasterKey: Failed to set ssl key (code: " << ret << ")";
    return;
  }
#endif
}

std::string AesIcmKeyDerivation::printType() 
{
  ReadersLock lock(mutex_);

  std::stringstream sstr;
  sstr << "AesIcm" << key_length_ << "KeyDerivation";
  return sstr.str();
}

bool AesIcmKeyDerivation::calcCtr(kd_dir dir, seq_nr_t* r, satp_prf_label label, seq_nr_t seq_nr)
{
  *r = 0;
  if(ld_kdr_ >= 0)
    *r = seq_nr >> ld_kdr_;

// TODO: determine whether to generate a key or not
//   if(key_store_[dir][label].key_.getBuf() && key_store_[dir][label].r_ == *r) {
//     if(!(*r) || (seq_nr % (*r)))
//       return false;
//   }

  if(master_salt_.getLength() != SALT_LENGTH) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_CRIT) << "KeyDerivation::calcCtr: salt lengths don't match";
    return false;
  }
  memcpy(ctr_.salt_.buf_, master_salt_.getBuf(), SALT_LENGTH);
  ctr_.salt_.zero_ = 0;
  ctr_.params_.label_ ^= label;
  ctr_.params_.r_ ^= SEQ_NR_T_HTON(*r);

  return true;
}

bool AesIcmKeyDerivation::generate(kd_dir dir, satp_prf_label label, seq_nr_t seq_nr, Buffer& key) 
{
//  ReadersLock lock(mutex_);
  WritersLock lock(mutex_);

  seq_nr_t r;
  calcCtr(dir, &r, label, seq_nr);
// TODO: return stored key
//  bool result = calcCtr(dir, &r, label, seq_nr);
//  if(!result) {
//     if(len > kd->key_store_[dir][label].key_.length_) {
//       log_printf(WARNING, "stored (old) key for label 0x%02X is too short, filling with zeros", label);
//       memset(key, 0, len);
//       len = kd->key_store_[dir][label].key_.length_;
//     }
//     memcpy(key, kd->key_store_[dir][label].key_.buf_, len);
//     return false;
//  }


#ifndef USE_SSL_CRYPTO
  gcry_error_t err = gcry_cipher_reset(handle_);
  if(err) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to reset cipher: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }

  err = gcry_cipher_setctr(handle_, ctr_.buf_, CTR_LENGTH);
  if(err) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to set CTR: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
    return false;
  }

  std::memset(key.getBuf(), 0, key.getLength());
  err = gcry_cipher_encrypt(handle_, key, key.getLength(), NULL, 0);
  if(err) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "KeyDerivation::generate: Failed to generate cipher bitstream: " << gpg_strerror_r(err, buf, STERROR_TEXT_MAX);
  }
  return true;
#else
  if(CTR_LENGTH != AES_BLOCK_SIZE) {
    char buf[STERROR_TEXT_MAX];
    buf[0] = 0;
    cLog.msg(Log::PRIO_ERR) << "AesIcmCipher: Failed to set cipher CTR: size don't fits";
    return false;
  }
  u_int32_t num = 0;
  std::memset(ecount_buf_, 0, AES_BLOCK_SIZE);
  std::memset(key.getBuf(), 0, key.getLength());
  AES_ctr128_encrypt(key.getBuf(), key.getBuf(), key.getLength(), &aes_key_, ctr_.buf_, ecount_buf_, &num);
#endif
  
// TODO: store key if key derivation rate is != 0
//   if(!ld_kdr_)
//     return true;

//   if(!kd->key_store_[dir][label].key_.buf_) {
//     kd->key_store_[dir][label].key_.length_ = 0;
//     kd->key_store_[dir][label].key_.buf_ = malloc(len);
//     if(!kd->key_store_[dir][label].key_.buf_)
//       return -2;

//     kd->key_store_[dir][label].key_.length_ = len;
//   }
//   else if(kd->key_store_[dir][label].key_.length_ < len) {
//     u_int8_t* tmp = realloc(kd->key_store_[dir][label].key_.buf_, len);
//     if(!tmp)
//       return -2;

//     kd->key_store_[dir][label].key_.buf_ = tmp;
//     kd->key_store_[dir][label].key_.length_ = len;
//   }

//   memcpy(kd->key_store_[dir][label].key_.buf_, key, len);
//   kd->key_store_[dir][label].r_ = r;

  return true;
}
#endif