/*

* TLS Handshake State Transitions

* (C) 2004-2006,2011,2012 Jack Lloyd

*     2017 Harry Reimann, Rohde & Schwarz Cybersecurity

*

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

*/

#include <botan/internal/tls_handshake_transitions.h>

#include <botan/tls_exceptn.h>

#include <sstream>

namespace Botan::TLS {

namespace {

uint32_t bitmask_for_handshake_type(Handshake_Type type)

   {

   switch(type)

      {

      case HELLO_VERIFY_REQUEST:

         return (1 << 0);

      case HELLO_REQUEST:

         return (1 << 1);

      case CLIENT_HELLO:

         return (1 << 2);

      case SERVER_HELLO:

         return (1 << 3);

      case CERTIFICATE:

         return (1 << 4);

      case CERTIFICATE_URL:

         return (1 << 5);

      case CERTIFICATE_STATUS:

         return (1 << 6);

      case SERVER_KEX:

         return (1 << 7);

      case CERTIFICATE_REQUEST:

         return (1 << 8);

      case SERVER_HELLO_DONE:

         return (1 << 9);

      case CERTIFICATE_VERIFY:

         return (1 << 10);

      case CLIENT_KEX:

         return (1 << 11);

      case NEW_SESSION_TICKET:

         return (1 << 12);

      case HANDSHAKE_CCS:

         return (1 << 13);

      case FINISHED:

         return (1 << 14);

      // allow explicitly disabling new handshakes

      case HANDSHAKE_NONE:

         return 0;

      }

   throw TLS_Exception(Alert::UNEXPECTED_MESSAGE,

                       "Unknown TLS handshake message type " + std::to_string(type));

   }

std::string handshake_mask_to_string(uint32_t mask, char combiner)

   {

   const Handshake_Type types[] =

      {

      HELLO_VERIFY_REQUEST,

      HELLO_REQUEST,

      CLIENT_HELLO,

      SERVER_HELLO,

      CERTIFICATE,

      CERTIFICATE_URL,

      CERTIFICATE_STATUS,

      SERVER_KEX,

      CERTIFICATE_REQUEST,

      SERVER_HELLO_DONE,

      CERTIFICATE_VERIFY,

      CLIENT_KEX,

      NEW_SESSION_TICKET,

      HANDSHAKE_CCS,

      FINISHED

      };

   std::ostringstream o;

   bool empty = true;

   for(auto&& t : types)

      {

      if(mask & bitmask_for_handshake_type(t))

         {

         if(!empty)

            { o << combiner; }

         o << handshake_type_to_string(t);

         empty = false;

         }

      }

   return o.str();

   }

}

bool Handshake_Transitions::received_handshake_msg(Handshake_Type msg_type) const

   {

   const uint32_t mask = bitmask_for_handshake_type(msg_type);

   return (m_hand_received_mask & mask) != 0;

   }

void Handshake_Transitions::confirm_transition_to(Handshake_Type msg_type)

   {

   const uint32_t mask = bitmask_for_handshake_type(msg_type);

   m_hand_received_mask |= mask;

   const bool ok = (m_hand_expecting_mask & mask) != 0; // overlap?

   if(!ok)

      {

      const uint32_t seen_so_far = m_hand_received_mask & ~mask;

      std::ostringstream msg;

      msg << "Unexpected state transition in handshake got a " << handshake_type_to_string(msg_type);

      if(m_hand_expecting_mask == 0)

         { msg << " not expecting messages"; }

      else

         { msg << " expected " << handshake_mask_to_string(m_hand_expecting_mask, '|'); }

      if(seen_so_far != 0)

         { msg << " seen " << handshake_mask_to_string(seen_so_far, '+'); }

      throw Unexpected_Message(msg.str());

      }

   /* We don't know what to expect next, so force a call to

      set_expected_next; if it doesn't happen, the next transition

      check will always fail which is what we want.

   */

   m_hand_expecting_mask = 0;

   }

void Handshake_Transitions::set_expected_next(Handshake_Type msg_type)

   {

   m_hand_expecting_mask |= bitmask_for_handshake_type(msg_type);

   }

void Handshake_Transitions::set_expected_next(const std::vector<Handshake_Type>& msg_types)

   {

   for (const auto type : msg_types)

      {

      set_expected_next(type);

      }

   }

bool Handshake_Transitions::change_cipher_spec_expected() const

   {

   return (bitmask_for_handshake_type(HANDSHAKE_CCS) & m_hand_expecting_mask) != 0;

   }

}