/*
* TLS Channel
* (C) 2011,2012,2014,2015 Jack Lloyd
*     2016 Matthias Gierlings
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#ifndef BOTAN_TLS_CHANNEL_H_
#define BOTAN_TLS_CHANNEL_H_

#include <botan/tls_session.h>
#include <botan/tls_alert.h>
#include <botan/tls_session_manager.h>
#include <botan/tls_callbacks.h>
#include <botan/x509cert.h>
#include <functional>
#include <vector>
#include <string>
#include <map>

namespace Botan {

namespace TLS {

class Connection_Cipher_State;
class Connection_Sequence_Numbers;
class Handshake_State;
class Handshake_Message;
class Client_Hello;
class Server_Hello;
class Policy;

/**
* Generic interface for TLS endpoint
*/
class BOTAN_PUBLIC_API(2,0) Channel
   {
   public:
      typedef std::function<void (const uint8_t[], size_t)> output_fn;
      typedef std::function<void (const uint8_t[], size_t)> data_cb;
      typedef std::function<void (Alert, const uint8_t[], size_t)> alert_cb;
      typedef std::function<bool (const Session&)> handshake_cb;
      typedef std::function<void (const Handshake_Message&)> handshake_msg_cb;
      static size_t IO_BUF_DEFAULT_SIZE;

      /**
      * Set up a new TLS session
      *
      * @param callbacks contains a set of callback function references
      *        required by the TLS endpoint.
      *
      * @param session_manager manages session state
      *
      * @param rng a random number generator
      *
      * @param policy specifies other connection policy information
      *
      * @param is_datagram whether this is a DTLS session
      *
      * @param io_buf_sz This many bytes of memory will
      *        be preallocated for the read and write buffers. Smaller
      *        values just mean reallocations and copies are more likely.
      */
      Channel(Callbacks& callbacks,
              Session_Manager& session_manager,
              RandomNumberGenerator& rng,
              const Policy& policy,
              bool is_datagram,
              size_t io_buf_sz = IO_BUF_DEFAULT_SIZE);

      /**
       * DEPRECATED. This constructor is only provided for backward
       * compatibility and should not be used in new implementations.
       * (Not marked deprecated since it is only called internally, by
       * other deprecated constructors)
       */
      Channel(output_fn out,
              data_cb app_data_cb,
              alert_cb alert_cb,
              handshake_cb hs_cb,
              handshake_msg_cb hs_msg_cb,
              Session_Manager& session_manager,
              RandomNumberGenerator& rng,
              const Policy& policy,
              bool is_datagram,
              size_t io_buf_sz = IO_BUF_DEFAULT_SIZE);

      Channel(const Channel&) = delete;

      Channel& operator=(const Channel&) = delete;

      virtual ~Channel();

      /**
      * Inject TLS traffic received from counterparty
      * @return a hint as the how many more bytes we need to process the
      *         current record (this may be 0 if on a record boundary)
      */
      size_t received_data(const uint8_t buf[], size_t buf_size);

      /**
      * Inject TLS traffic received from counterparty
      * @return a hint as the how many more bytes we need to process the
      *         current record (this may be 0 if on a record boundary)
      */
      size_t received_data(const std::vector<uint8_t>& buf);

      /**
      * Inject plaintext intended for counterparty
      * Throws an exception if is_active() is false
      */
      void send(const uint8_t buf[], size_t buf_size);

      /**
      * Inject plaintext intended for counterparty
      * Throws an exception if is_active() is false
      */
      void send(const std::string& val);

      /**
      * Inject plaintext intended for counterparty
      * Throws an exception if is_active() is false
      */
      template<typename Alloc>
         void send(const std::vector<unsigned char, Alloc>& val)
         {
         send(val.data(), val.size());
         }

      /**
      * Send a TLS alert message. If the alert is fatal, the internal
      * state (keys, etc) will be reset.
      * @param alert the Alert to send
      */
      void send_alert(const Alert& alert);

      /**
      * Send a warning alert
      */
      void send_warning_alert(Alert::Type type) { send_alert(Alert(type, false)); }

      /**
      * Send a fatal alert
      */
      void send_fatal_alert(Alert::Type type) { send_alert(Alert(type, true)); }

      /**
      * Send a close notification alert
      */
      void close() { send_warning_alert(Alert::CLOSE_NOTIFY); }

      /**
      * @return true iff the connection is active for sending application data
      */
      bool is_active() const;

      /**
      * @return true iff the connection has been definitely closed
      */
      bool is_closed() const;


      /**
      * @return certificate chain of the peer (may be empty)
      */
      std::vector<X509_Certificate> peer_cert_chain() const;

      /**
      * Key material export (RFC 5705)
      * @param label a disambiguating label string
      * @param context a per-association context value
      * @param length the length of the desired key in bytes
      * @return key of length bytes
      */
      SymmetricKey key_material_export(const std::string& label,
                                       const std::string& context,
                                       size_t length) const;

      /**
      * Attempt to renegotiate the session
      * @param force_full_renegotiation if true, require a full renegotiation,
      * otherwise allow session resumption
      */
      void renegotiate(bool force_full_renegotiation = false);

      /**
      * @return true iff the counterparty supports the secure
      * renegotiation extensions.
      */
      bool secure_renegotiation_supported() const;

      /**
      * Perform a handshake timeout check. This does nothing unless
      * this is a DTLS channel with a pending handshake state, in
      * which case we check for timeout and potentially retransmit
      * handshake packets.
      */
      bool timeout_check();

      virtual std::string application_protocol() const = 0;

   protected:

      virtual void process_handshake_msg(const Handshake_State* active_state,
                                         Handshake_State& pending_state,
                                         Handshake_Type type,
                                         const std::vector<uint8_t>& contents) = 0;

      virtual void initiate_handshake(Handshake_State& state,
                                      bool force_full_renegotiation) = 0;

      virtual std::vector<X509_Certificate>
         get_peer_cert_chain(const Handshake_State& state) const = 0;

      virtual Handshake_State* new_handshake_state(class Handshake_IO* io) = 0;

      Handshake_State& create_handshake_state(Protocol_Version version);

      void inspect_handshake_message(const Handshake_Message& msg);

      void activate_session();

      void change_cipher_spec_reader(Connection_Side side);

      void change_cipher_spec_writer(Connection_Side side);

      /* secure renegotiation handling */

      void secure_renegotiation_check(const Client_Hello* client_hello);
      void secure_renegotiation_check(const Server_Hello* server_hello);

      std::vector<uint8_t> secure_renegotiation_data_for_client_hello() const;
      std::vector<uint8_t> secure_renegotiation_data_for_server_hello() const;

      RandomNumberGenerator& rng() { return m_rng; }

      Session_Manager& session_manager() { return m_session_manager; }

      const Policy& policy() const { return m_policy; }

      bool save_session(const Session& session);

      Callbacks& callbacks() const { return m_callbacks; }
   private:
      void init(size_t io_buf_sze);

      void send_record(uint8_t record_type, const std::vector<uint8_t>& record);

      void send_record_under_epoch(uint16_t epoch, uint8_t record_type,
                                   const std::vector<uint8_t>& record);

      void send_record_array(uint16_t epoch, uint8_t record_type,
                             const uint8_t input[], size_t length);

      void write_record(Connection_Cipher_State* cipher_state,
                        uint16_t epoch, uint8_t type, const uint8_t input[], size_t length);

      Connection_Sequence_Numbers& sequence_numbers() const;

      std::shared_ptr<Connection_Cipher_State> read_cipher_state_epoch(uint16_t epoch) const;

      std::shared_ptr<Connection_Cipher_State> write_cipher_state_epoch(uint16_t epoch) const;

      void reset_state();

      const Handshake_State* active_state() const { return m_active_state.get(); }

      const Handshake_State* pending_state() const { return m_pending_state.get(); }

      /* methods to handle incoming traffic through Channel::receive_data. */
      void process_handshake_ccs(const secure_vector<uint8_t>& record,
                                 uint64_t record_sequence,
                                 Record_Type record_type,
                                 Protocol_Version record_version);

      void process_application_data(uint64_t req_no, const secure_vector<uint8_t>& record);

      void process_alert(const secure_vector<uint8_t>& record);

      bool m_is_datagram;

      /* callbacks */
      std::unique_ptr<Compat_Callbacks> m_compat_callbacks;
      Callbacks& m_callbacks;

      /* external state */
      Session_Manager& m_session_manager;
      const Policy& m_policy;
      RandomNumberGenerator& m_rng;

      /* sequence number state */
      std::unique_ptr<Connection_Sequence_Numbers> m_sequence_numbers;

      /* pending and active connection states */
      std::unique_ptr<Handshake_State> m_active_state;
      std::unique_ptr<Handshake_State> m_pending_state;

      /* cipher states for each epoch */
      std::map<uint16_t, std::shared_ptr<Connection_Cipher_State>> m_write_cipher_states;
      std::map<uint16_t, std::shared_ptr<Connection_Cipher_State>> m_read_cipher_states;

      /* I/O buffers */
      secure_vector<uint8_t> m_writebuf;
      secure_vector<uint8_t> m_readbuf;
   };

}

}

#endif