/*
 * AuthBackendChallengeResponse.cpp
 *
 * Copyright (C) 2009 Matthias Schiffer <matthias@gamezock.de>
 *
 * This program is free software: you can redistribute it and/or modify it
 * under the terms of the GNU Lesser 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License along
 * with this program. If not, see <http://www.gnu.org/licenses/>.
 */

#include "AuthBackendChallengeResponse.h"

#include <Common/Hash.h>

namespace Mad {
namespace Modules {
namespace AuthBackendChallengeResponse {

const std::string AuthBackendChallengeResponse::methodName = "Challenge-Response";

AuthBackendChallengeResponse::AuthContextChallengeResponse::AuthContextChallengeResponse(AuthBackendChallengeResponse *backend) : authenticated(false) {
  challenge.reserve(32);

  for(int i = 0; i < 32; ++i)
    challenge.push_back(backend->randomGenerator());
}

boost::shared_ptr<Common::AuthContext> AuthBackendChallengeResponse::authenticate(boost::shared_ptr<Common::AuthProvider> provider, const std::string &subMethod,
    const std::string &user, const std::vector<boost::uint8_t> &data, std::vector<boost::uint8_t> &response,
    boost::shared_ptr<Common::AuthContext> context) throw(Core::Exception) {
  if(context && dynamic_cast<AuthContextChallengeResponse*>(context.get()) == 0)
    throw(Core::Exception(Core::Exception::INVALID_INPUT));

  std::vector<std::string> allowedMethods = getSubMethods(provider);
  if(std::find(allowedMethods.begin(), allowedMethods.end(), subMethod) == allowedMethods.end())
    throw(Core::Exception(Core::Exception::INVALID_INPUT));

  if(!context) {
    boost::shared_ptr<AuthContextChallengeResponse> contextCR(new AuthContextChallengeResponse(this));
    context = contextCR;

    response.insert(response.end(), contextCR->challenge.begin(), contextCR->challenge.end());
  }
  else {
    boost::shared_ptr<AuthContextChallengeResponse> contextCR = boost::dynamic_pointer_cast<AuthContextChallengeResponse>(context);

    std::vector<boost::uint8_t> password = provider->getPassword(user, subMethod);
    if(password.empty())
      throw Core::Exception(Core::Exception::AUTHENTICATION);

    password.insert(password.end(), contextCR->challenge.begin(), contextCR->challenge.end());

    password = Common::Hash::hash(password, subMethod);

    if(password.size() != data.size() || !std::equal(password.begin(), password.end(), data.begin()))
      throw Core::Exception(Core::Exception::AUTHENTICATION);

    contextCR->authenticated = true;
  }


  return context;
}

}
}
}