/*
 * GSSAPIAuthRequest.cpp
 *
 * Copyright (C) 2008 Matthias Schiffer <matthias@gamezock.de>
 *
 * This program 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/>.
 */

#include "GSSAPIAuthRequest.h"
#include "../Logger.h"
#include <Net/Connection.h>

#include <cstring>

namespace Mad {
namespace Common {
namespace Requests {

// TODO Logging & error handling!

GSSAPIAuthRequest::~GSSAPIAuthRequest() {
  OM_uint32 minStat;

  if(gssServiceName != GSS_C_NO_NAME)
    gss_release_name(&minStat, &gssServiceName);
}

void GSSAPIAuthRequest::sendRequest(Net::Connection *connection, uint16_t requestId) {
  OM_uint32 majStat, minStat;
  gss_buffer_desc buffer;

  buffer.length = serviceName.length();
  buffer.value = std::malloc(buffer.length);
  std::memcpy(buffer.value, serviceName.c_str(), buffer.length);

  majStat = gss_import_name(&minStat, &buffer, GSS_C_NT_HOSTBASED_SERVICE, &gssServiceName);

  std::free(buffer.value);

  if(majStat != GSS_S_COMPLETE) {
    gssServiceName = GSS_C_NO_NAME;
    return;
  }

  majStat = gss_init_sec_context(&minStat, GSS_C_NO_CREDENTIAL, &gssContext, gssServiceName, GSS_C_NO_OID, GSS_C_MUTUAL_FLAG | GSS_C_REPLAY_FLAG,
      0, GSS_C_NO_CHANNEL_BINDINGS, GSS_C_NO_BUFFER, 0, &buffer, 0, 0);

  if(majStat == GSS_S_COMPLETE) {
    Logger::log(Logger::VERBOSE, "GSS context established.");
    gssContinue = false;
  }
  else if(majStat != GSS_S_CONTINUE_NEEDED) {
    gss_release_buffer(&minStat, &buffer);
    return;
  }

  if(!connection->send(Net::Packet(Net::Packet::GSSAPI_AUTH, requestId, buffer.value, buffer.length))) {
    gss_release_buffer(&minStat, &buffer);
    return;
  }

  gss_release_buffer(&minStat, &buffer);
}

void GSSAPIAuthRequest::handlePacket(Net::Connection *connection, const Net::Packet &packet) {
  if(packet.getType() != Net::Packet::GSSAPI_AUTH) {
    finishWithError(Exception(Exception::UNEXPECTED_PACKET));
    return; // TODO Logging
  }

  OM_uint32 majStat, minStat;
  gss_buffer_desc recvBuffer, sendBuffer;

  // Needs error handling!

  if(gssContinue) {
    recvBuffer.length = packet.getLength();
    recvBuffer.value = std::malloc(recvBuffer.length);
    std::memcpy(recvBuffer.value, packet.getData(), recvBuffer.length);

    majStat = gss_init_sec_context(&minStat, GSS_C_NO_CREDENTIAL, &gssContext, gssServiceName, GSS_C_NO_OID, GSS_C_MUTUAL_FLAG | GSS_C_REPLAY_FLAG | GSS_C_INTEG_FLAG,
        0, GSS_C_NO_CHANNEL_BINDINGS, &recvBuffer, 0, &sendBuffer, 0, 0);

    std::free(recvBuffer.value);

    if(majStat == GSS_S_COMPLETE) {
      Logger::log(Logger::VERBOSE, "GSS context established.");
      gssContinue = false;
    }
    else if(majStat != GSS_S_CONTINUE_NEEDED) {
      gss_release_buffer(&minStat, &sendBuffer);
      return;
    }

    if(!connection->send(Net::Packet(Net::Packet::GSSAPI_AUTH, packet.getRequestId(), sendBuffer.value, sendBuffer.length))) {
      gss_release_buffer(&minStat, &sendBuffer);
      return;
    }

    gss_release_buffer(&minStat, &sendBuffer);
  }
  else {
    recvBuffer.length = packet.getLength();
    recvBuffer.value = std::malloc(recvBuffer.length);
    std::memcpy(recvBuffer.value, packet.getData(), recvBuffer.length);

    const gnutls_datum_t *cert = connection->getPeerCertificate();

    sendBuffer.length = cert->size;
    sendBuffer.value = cert->data;

    majStat = gss_verify_mic(&minStat, gssContext, &sendBuffer, &recvBuffer, 0);

    std::free(recvBuffer.value);

    if(majStat != GSS_S_COMPLETE)
      return;

    connection->setAuthenticated();
    Logger::log(Logger::VERBOSE, "Authentication complete.");

    majStat = gss_delete_sec_context(&minStat, &gssContext, &sendBuffer);

    if(majStat != GSS_S_COMPLETE) {
      gss_release_buffer(&minStat, &sendBuffer);
      return;
    }

    if(!connection->send(Net::Packet(Net::Packet::GSSAPI_AUTH, packet.getRequestId(), sendBuffer.value, sendBuffer.length))) {
      gss_release_buffer(&minStat, &sendBuffer);
      return;
    }

    gss_release_buffer(&minStat, &sendBuffer);

    finish();
  }
}

}
}
}