/*
 *  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 anytun.org <satp@wirdorange.org>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License version 2
 *  as published by the Free Software Foundation.
 *
 *  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 (see the file COPYING included with this
 *  distribution); if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "authAlgo.h"
#include "log.h"
#include "buffer.h"
#include "authTag.h"
#include "threadUtils.hpp"

#include <gcrypt.h>

//****** NullAuthAlgo ******

AuthTag NullAuthAlgo::calc(const Buffer& buf)
{
  return AuthTag(0);
}

//****** Sha1AuthAlgo ******

Sha1AuthAlgo::Sha1AuthAlgo() : ctx_(NULL)
{
  Lock lock(mutex_);

  gcry_error_t err = gcry_md_open( &ctx_, GCRY_MD_SHA1, GCRY_MD_FLAG_HMAC );
  if( err )
    cLog.msg(Log::PRIO_CRIT) << "Sha1AuthAlgo::Sha1AuthAlgo: Failed to open message digest algo";
}

Sha1AuthAlgo::~Sha1AuthAlgo()
{
  Lock lock(mutex_);

  gcry_md_close( ctx_ );
  cLog.msg(Log::PRIO_DEBUG) << "Sha1AuthAlgo::~Sha1AuthAlgo: closed hmac handler";
}

void Sha1AuthAlgo::setKey(Buffer key)
{
  Lock lock(mutex_);

  gcry_error_t err;
  err = gcry_md_setkey( ctx_, key.getBuf(), key.getLength() );
  if( err )
    cLog.msg(Log::PRIO_ERR) << "Sha1AuthAlgo::setKey: Failed to set cipher key: " << gpg_strerror( err );
}

AuthTag Sha1AuthAlgo::calc(const Buffer& buf)
{
  Lock lock(mutex_);

  // gcry_error_t err;
  AuthTag hmac(10);      // 10byte
  gcry_mpi_t tmp = gcry_mpi_new(160);   // 20byte

  gcry_md_write( ctx_, static_cast<Buffer>(buf).getBuf(), buf.getLength() );
  gcry_md_final( ctx_ );
  gcry_mpi_scan( &tmp, GCRYMPI_FMT_STD, gcry_md_read(ctx_, 0), 20, NULL );
  gcry_mpi_clear_highbit( tmp, 81 );    // truncate hmac from 20byte to 10byte
  gcry_mpi_print( GCRYMPI_FMT_STD, hmac, hmac.getLength(), NULL, tmp );
  return hmac;
}