/*

* 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/tls_algos.h>

#include <botan/tls_magic.h>

#include <botan/tls_version.h>

#include <botan/aead.h>

#include <vector>

#include <chrono>

#include <functional>

namespace Botan {

namespace TLS {

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.get();

         }

      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, uint8_t 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; }

      std::chrono::seconds age() const

         {

         return std::chrono::duration_cast<std::chrono::seconds>(

            std::chrono::system_clock::now() - m_start_time);

         }

   private:

      std::chrono::system_clock::time_point m_start_time;

      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(NO_RECORD)

         {}

      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,

                              uint8_t 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,

                  uint8_t 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,

                          get_cipherstate_fn get_cipherstate,

                          bool allow_epoch0_restart);

}

}

#endif