/*
* Finished Message
* (C) 2004-2006,2012 Jack Lloyd
*     2021 Elektrobit Automotive GmbH
*     2022 René Meusel, Hannes Rantzsch - neXenio GmbH
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/tls_messages.h>
#include <botan/kdf.h>
#include <botan/internal/tls_handshake_io.h>
#include <botan/internal/tls_handshake_state.h>

namespace Botan::TLS {

namespace {

/*
* Compute the verify_data for TLS 1.2
*/
std::vector<uint8_t> finished_compute_verify_12(const Handshake_State& state,
      Connection_Side side)
   {
   const uint8_t TLS_CLIENT_LABEL[] =
      {
      0x63, 0x6C, 0x69, 0x65, 0x6E, 0x74, 0x20, 0x66, 0x69, 0x6E, 0x69,
      0x73, 0x68, 0x65, 0x64
      };

   const uint8_t TLS_SERVER_LABEL[] =
      {
      0x73, 0x65, 0x72, 0x76, 0x65, 0x72, 0x20, 0x66, 0x69, 0x6E, 0x69,
      0x73, 0x68, 0x65, 0x64
      };

   auto prf = state.protocol_specific_prf();

   std::vector<uint8_t> input;
   std::vector<uint8_t> label;
   label += (side == CLIENT)
            ? std::make_pair(TLS_CLIENT_LABEL, sizeof(TLS_CLIENT_LABEL))
            : std::make_pair(TLS_SERVER_LABEL, sizeof(TLS_SERVER_LABEL));

   input += state.hash().final(state.ciphersuite().prf_algo());

   return unlock(prf->derive_key(12, state.session_keys().master_secret(), input, label));
   }

} // namespace

std::vector<uint8_t> Finished::serialize() const
   {
   return m_verification_data;
   }

Finished::Finished(const std::vector<uint8_t>& buf) : m_verification_data(buf) {}

std::vector<uint8_t> Finished::verify_data() const
   {
   return m_verification_data;
   }

Finished_12::Finished_12(Handshake_IO& io,
                      Handshake_State& state,
                      Connection_Side side)
   {
   m_verification_data = finished_compute_verify_12(state, side);
   state.hash().update(io.send(*this));
   }

bool Finished_12::verify(const Handshake_State& state,
                         Connection_Side side) const
   {
   std::vector<uint8_t> computed_verify = finished_compute_verify_12(state, side);

#if defined(BOTAN_UNSAFE_FUZZER_MODE)
   return true;
#else
   return (m_verification_data.size() == computed_verify.size()) &&
          constant_time_compare(m_verification_data.data(), computed_verify.data(), computed_verify.size());
#endif
   }

}