/*
* TLS Record Handling
* (C) 2004-2012 Jack Lloyd
*     2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_TLS_RECORDS_H_
#define BOTAN_TLS_RECORDS_H_

#include <botan/aead.h>
#include <botan/tls_algos.h>
#include <botan/tls_magic.h>
#include <botan/tls_version.h>
#include <botan/internal/tls_channel_impl.h>
#include <chrono>
#include <functional>
#include <vector>

namespace Botan::TLS {

class Callbacks;
class Ciphersuite;
class Session_Keys;

class Connection_Sequence_Numbers;

/**
* TLS Cipher State
*/
class Connection_Cipher_State final {
   public:
      /**
      * Initialize a new cipher state
      */
      Connection_Cipher_State(Protocol_Version version,
                              Connection_Side which_side,
                              bool is_our_side,
                              const Ciphersuite& suite,
                              const Session_Keys& keys,
                              bool uses_encrypt_then_mac);

      AEAD_Mode& aead() {
         BOTAN_ASSERT_NONNULL(m_aead.get());
         return *m_aead;
      }

      std::vector<uint8_t> aead_nonce(uint64_t seq, RandomNumberGenerator& rng);

      std::vector<uint8_t> aead_nonce(const uint8_t record[], size_t record_len, uint64_t seq);

      std::vector<uint8_t> format_ad(uint64_t seq, Record_Type type, Protocol_Version version, uint16_t ptext_length);

      size_t nonce_bytes_from_handshake() const { return m_nonce_bytes_from_handshake; }

      size_t nonce_bytes_from_record() const { return m_nonce_bytes_from_record; }

      Nonce_Format nonce_format() const { return m_nonce_format; }

   private:
      std::unique_ptr<AEAD_Mode> m_aead;

      std::vector<uint8_t> m_nonce;
      Nonce_Format m_nonce_format;
      size_t m_nonce_bytes_from_handshake;
      size_t m_nonce_bytes_from_record;
};

class Record_Header final {
   public:
      Record_Header(uint64_t sequence, Protocol_Version version, Record_Type type) :
            m_needed(0), m_sequence(sequence), m_version(version), m_type(type) {}

      Record_Header(size_t needed) :
            m_needed(needed), m_sequence(0), m_version(Protocol_Version()), m_type(Record_Type::Invalid) {}

      size_t needed() const { return m_needed; }

      Protocol_Version version() const {
         BOTAN_ASSERT_NOMSG(m_needed == 0);
         return m_version;
      }

      uint64_t sequence() const {
         BOTAN_ASSERT_NOMSG(m_needed == 0);
         return m_sequence;
      }

      uint16_t epoch() const { return static_cast<uint16_t>(sequence() >> 48); }

      Record_Type type() const {
         BOTAN_ASSERT_NOMSG(m_needed == 0);
         return m_type;
      }

   private:
      size_t m_needed;
      uint64_t m_sequence;
      Protocol_Version m_version;
      Record_Type m_type;
};

/**
* Create an initial (unencrypted) TLS handshake record
* @param write_buffer the output record is placed here
* @param record_type the record layer type
* @param record_version the record layer version
* @param record_sequence the record layer sequence number
* @param message the record contents
* @param message_len is size of message
*/
void write_unencrypted_record(secure_vector<uint8_t>& write_buffer,
                              Record_Type record_type,
                              Protocol_Version record_version,
                              uint64_t record_sequence,
                              const uint8_t* message,
                              size_t message_len);

/**
* Create a TLS record
* @param write_buffer the output record is placed here
* @param record_type the record layer type
* @param record_version the record layer version
* @param record_sequence the record layer sequence number
* @param message the record contents
* @param message_len is size of message
* @param cipherstate is the writing cipher state
* @param rng is a random number generator
*/
void write_record(secure_vector<uint8_t>& write_buffer,
                  Record_Type record_type,
                  Protocol_Version record_version,
                  uint64_t record_sequence,
                  const uint8_t* message,
                  size_t message_len,
                  Connection_Cipher_State& cipherstate,
                  RandomNumberGenerator& rng);

// epoch -> cipher state
typedef std::function<std::shared_ptr<Connection_Cipher_State>(uint16_t)> get_cipherstate_fn;

/**
* Decode a TLS record
* @return zero if full message, else number of bytes still needed
*/
Record_Header read_record(bool is_datagram,
                          secure_vector<uint8_t>& read_buffer,
                          const uint8_t input[],
                          size_t input_len,
                          size_t& consumed,
                          secure_vector<uint8_t>& record_buf,
                          Connection_Sequence_Numbers* sequence_numbers,
                          const get_cipherstate_fn& get_cipherstate,
                          bool allow_epoch0_restart);

}  // namespace Botan::TLS

#endif
