/*

* (C) 2016 Jack Lloyd

*

* Botan is released under the Simplified BSD License (see license.txt)

*/

#include <botan/rng.h>

#include <botan/internal/loadstor.h>

#if defined(BOTAN_HAS_ENTROPY_SOURCE)

   #include <botan/entropy_src.h>

#endif

#if defined(BOTAN_HAS_SYSTEM_RNG)

   #include <botan/system_rng.h>

#endif

#if defined(BOTAN_HAS_OS_UTILS)

   #include <botan/internal/os_utils.h>

#endif

#include <array>

namespace Botan {

void RandomNumberGenerator::randomize_with_ts_input(std::span<uint8_t> output) {

   if(this->accepts_input()) {

      std::array<uint8_t, 32> additional_input = {0};

#if defined(BOTAN_HAS_OS_UTILS)

      store_le(std::span{additional_input}.subspan<0, 8>(), OS::get_high_resolution_clock());

      store_le(std::span{additional_input}.subspan<8, 4>(), OS::get_process_id());

      constexpr size_t offset = 12;

#else

      constexpr size_t offset = 0;

#endif

#if defined(BOTAN_HAS_SYSTEM_RNG)

      system_rng().randomize(std::span{additional_input}.subspan<offset>());

#else

      BOTAN_UNUSED(offset);

#endif

      this->fill_bytes_with_input(output, additional_input);

   } else {

      this->fill_bytes_with_input(output, {});

   }

}

size_t RandomNumberGenerator::reseed(Entropy_Sources& srcs, size_t poll_bits, std::chrono::milliseconds poll_timeout) {

   if(this->accepts_input()) {

#if defined(BOTAN_HAS_ENTROPY_SOURCE)

      return srcs.poll(*this, poll_bits, poll_timeout);

#else

      BOTAN_UNUSED(srcs, poll_bits, poll_timeout);

#endif

   }

   return 0;

}

void RandomNumberGenerator::reseed_from_rng(RandomNumberGenerator& rng, size_t poll_bits) {

   if(this->accepts_input()) {

      this->add_entropy(rng.random_vec(poll_bits / 8));

   }

}

void Null_RNG::fill_bytes_with_input(std::span<uint8_t> output, std::span<const uint8_t> /* ignored */) {

   // throw if caller tries to obtain random bytes

   if(!output.empty()) {

      throw PRNG_Unseeded("Null_RNG called");

   }

}

}  // namespace Botan