/*
* Filter interface for Cipher_Modes
* (C) 2013,2014,2017 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/filters.h>

#include <botan/internal/rounding.h>

namespace Botan {

namespace {

size_t choose_update_size(size_t update_granularity) {
   const size_t target_size = 1024;

   if(update_granularity >= target_size) {
      return update_granularity;
   }

   return round_up(target_size, update_granularity);
}

}  // namespace

Cipher_Mode_Filter::Cipher_Mode_Filter(Cipher_Mode* mode) :
      Buffered_Filter(choose_update_size(mode->ideal_granularity()), mode->minimum_final_size()),
      m_mode(mode),
      m_buffer(m_mode->ideal_granularity()) {}

std::string Cipher_Mode_Filter::name() const {
   return m_mode->name();
}

void Cipher_Mode_Filter::set_iv(const InitializationVector& iv) {
   m_nonce = unlock(iv.bits_of());
}

void Cipher_Mode_Filter::set_key(const SymmetricKey& key) {
   m_mode->set_key(key);
}

Key_Length_Specification Cipher_Mode_Filter::key_spec() const {
   return m_mode->key_spec();
}

bool Cipher_Mode_Filter::valid_iv_length(size_t length) const {
   return m_mode->valid_nonce_length(length);
}

void Cipher_Mode_Filter::write(const uint8_t input[], size_t input_length) {
   Buffered_Filter::write(input, input_length);
}

void Cipher_Mode_Filter::end_msg() {
   Buffered_Filter::end_msg();
}

void Cipher_Mode_Filter::start_msg() {
   // m_nonce is empty unless set_iv() was called (it is cleared after each message).
   if(m_nonce.empty() && !m_mode->valid_nonce_length(0)) {
      throw Invalid_State("Cipher " + m_mode->name() + " requires a fresh nonce for each message");
   }

   m_mode->start(m_nonce);
   m_nonce.clear();
}

void Cipher_Mode_Filter::buffered_block(const uint8_t input[], size_t input_length) {
   while(input_length > 0) {
      const size_t take = std::min(m_mode->ideal_granularity(), input_length);

      m_buffer.assign(input, input + take);
      m_mode->update(m_buffer);

      send(m_buffer);

      input += take;
      input_length -= take;
   }
}

void Cipher_Mode_Filter::buffered_final(const uint8_t input[], size_t input_length) {
   secure_vector<uint8_t> buf(input, input + input_length);
   m_mode->finish(buf);
   send(buf);
}

}  // namespace Botan
