/*
* TLS Handshaking
* (C) 2004-2006,2011,2012,2015,2016 Jack Lloyd
*     2017 Harry Reimann, Rohde & Schwarz Cybersecurity
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/internal/tls_handshake_state.h>
#include <botan/internal/tls_record.h>
#include <botan/tls_messages.h>
#include <botan/kdf.h>
#include <sstream>

namespace Botan {

namespace TLS {

std::string Handshake_Message::type_string() const
   {
   return handshake_type_to_string(type());
   }

const char* handshake_type_to_string(Handshake_Type type)
   {
   switch(type)
      {
      case HELLO_VERIFY_REQUEST:
         return "hello_verify_request";

      case HELLO_REQUEST:
         return "hello_request";

      case CLIENT_HELLO:
         return "client_hello";

      case SERVER_HELLO:
         return "server_hello";

      case CERTIFICATE:
         return "certificate";

      case CERTIFICATE_URL:
         return "certificate_url";

      case CERTIFICATE_STATUS:
         return "certificate_status";

      case SERVER_KEX:
         return "server_key_exchange";

      case CERTIFICATE_REQUEST:
         return "certificate_request";

      case SERVER_HELLO_DONE:
         return "server_hello_done";

      case CERTIFICATE_VERIFY:
         return "certificate_verify";

      case CLIENT_KEX:
         return "client_key_exchange";

      case NEW_SESSION_TICKET:
         return "new_session_ticket";

      case HANDSHAKE_CCS:
         return "change_cipher_spec";

      case FINISHED:
         return "finished";

      case HANDSHAKE_NONE:
         return "invalid";
      }

   throw TLS_Exception(Alert::UNEXPECTED_MESSAGE,
                       "Unknown TLS handshake message type " + std::to_string(type));
   }

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)
   {
   const Handshake_Type types[] = {
      HELLO_VERIFY_REQUEST,
      HELLO_REQUEST,
      CLIENT_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 << ",";
         o << handshake_type_to_string(t);
         empty = false;
         }
      }

   return o.str();
   }

}

/*
* Initialize the SSL/TLS Handshake State
*/
Handshake_State::Handshake_State(Handshake_IO* io, Callbacks& cb) :
   m_callbacks(cb),
   m_handshake_io(io),
   m_version(m_handshake_io->initial_record_version())
   {
   }

void Handshake_State::note_message(const Handshake_Message& msg)
   {
   m_callbacks.tls_inspect_handshake_msg(msg);
   }

void Handshake_State::hello_verify_request(const Hello_Verify_Request& hello_verify)
   {
   note_message(hello_verify);

   m_client_hello->update_hello_cookie(hello_verify);
   hash().reset();
   hash().update(handshake_io().send(*m_client_hello));
   note_message(*m_client_hello);
   }

void Handshake_State::client_hello(Client_Hello* client_hello)
   {
   m_client_hello.reset(client_hello);
   note_message(*m_client_hello);
   }

void Handshake_State::server_hello(Server_Hello* server_hello)
   {
   m_server_hello.reset(server_hello);
   m_ciphersuite = Ciphersuite::by_id(m_server_hello->ciphersuite());
   note_message(*m_server_hello);
   }

void Handshake_State::server_certs(Certificate* server_certs)
   {
   m_server_certs.reset(server_certs);
   note_message(*m_server_certs);
   }

void Handshake_State::server_cert_status(Certificate_Status* server_cert_status)
   {
   m_server_cert_status.reset(server_cert_status);
   note_message(*m_server_cert_status);
   }

void Handshake_State::server_kex(Server_Key_Exchange* server_kex)
   {
   m_server_kex.reset(server_kex);
   note_message(*m_server_kex);
   }

void Handshake_State::cert_req(Certificate_Req* cert_req)
   {
   m_cert_req.reset(cert_req);
   note_message(*m_cert_req);
   }

void Handshake_State::server_hello_done(Server_Hello_Done* server_hello_done)
   {
   m_server_hello_done.reset(server_hello_done);
   note_message(*m_server_hello_done);
   }

void Handshake_State::client_certs(Certificate* client_certs)
   {
   m_client_certs.reset(client_certs);
   note_message(*m_client_certs);
   }

void Handshake_State::client_kex(Client_Key_Exchange* client_kex)
   {
   m_client_kex.reset(client_kex);
   note_message(*m_client_kex);
   }

void Handshake_State::client_verify(Certificate_Verify* client_verify)
   {
   m_client_verify.reset(client_verify);
   note_message(*m_client_verify);
   }

void Handshake_State::new_session_ticket(New_Session_Ticket* new_session_ticket)
   {
   m_new_session_ticket.reset(new_session_ticket);
   note_message(*m_new_session_ticket);
   }

void Handshake_State::server_finished(Finished* server_finished)
   {
   m_server_finished.reset(server_finished);
   note_message(*m_server_finished);
   }

void Handshake_State::client_finished(Finished* client_finished)
   {
   m_client_finished.reset(client_finished);
   note_message(*m_client_finished);
   }

void Handshake_State::set_version(const Protocol_Version& version)
   {
   m_version = version;
   }

void Handshake_State::compute_session_keys()
   {
   m_session_keys = Session_Keys(this, client_kex()->pre_master_secret(), false);
   }

void Handshake_State::compute_session_keys(const secure_vector<uint8_t>& resume_master_secret)
   {
   m_session_keys = Session_Keys(this, resume_master_secret, true);
   }

void Handshake_State::confirm_transition_to(Handshake_Type handshake_msg)
   {
   const uint32_t mask = bitmask_for_handshake_type(handshake_msg);

   m_hand_received_mask |= mask;

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

   if(!ok)
      throw Unexpected_Message("Unexpected state transition in handshake, got type " +
                               std::to_string(handshake_msg) +
                               " expected " + handshake_mask_to_string(m_hand_expecting_mask) +
                               " received " + handshake_mask_to_string(m_hand_received_mask));

   /* 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_State::set_expected_next(Handshake_Type handshake_msg)
   {
   m_hand_expecting_mask |= bitmask_for_handshake_type(handshake_msg);
   }

bool Handshake_State::received_handshake_msg(Handshake_Type handshake_msg) const
   {
   const uint32_t mask = bitmask_for_handshake_type(handshake_msg);

   return (m_hand_received_mask & mask) != 0;
   }

std::pair<Handshake_Type, std::vector<uint8_t>>
Handshake_State::get_next_handshake_msg()
   {
   const bool expecting_ccs =
      (bitmask_for_handshake_type(HANDSHAKE_CCS) & m_hand_expecting_mask) != 0;

   return m_handshake_io->get_next_record(expecting_ccs);
   }

std::string Handshake_State::srp_identifier() const
   {
#if defined(BOTAN_HAS_SRP6)
   // Authenticated via the successful key exchange
   if(ciphersuite().valid() && ciphersuite().kex_algo() == "SRP_SHA")
      return client_hello()->srp_identifier();
#endif

   return "";
   }


std::vector<uint8_t> Handshake_State::session_ticket() const
   {
   if(new_session_ticket() && !new_session_ticket()->ticket().empty())
      return new_session_ticket()->ticket();

   return client_hello()->session_ticket();
   }

KDF* Handshake_State::protocol_specific_prf() const
   {
   if(version().supports_ciphersuite_specific_prf())
      {
      const std::string prf_algo = ciphersuite().prf_algo();

      if(prf_algo == "MD5" || prf_algo == "SHA-1")
         return get_kdf("TLS-12-PRF(SHA-256)");

      return get_kdf("TLS-12-PRF(" + prf_algo + ")");
      }

   // Old PRF used in TLS v1.0, v1.1 and DTLS v1.0
   return get_kdf("TLS-PRF");
   }

namespace {

std::string choose_hash(const std::string& sig_algo,
                        std::vector<std::pair<std::string, std::string>>& supported_algos,
                        Protocol_Version negotiated_version,
                        const Policy& policy)
   {
   if(!negotiated_version.supports_negotiable_signature_algorithms())
      {
      if(sig_algo == "RSA")
         return "Parallel(MD5,SHA-160)";

      if(sig_algo == "DSA")
         return "SHA-1";

      if(sig_algo == "ECDSA")
         return "SHA-1";

      throw Internal_Error("Unknown TLS signature algo " + sig_algo);
      }

   if(!supported_algos.empty())
      {
      const std::vector<std::string> hashes = policy.allowed_signature_hashes();

      /*
      * Choose our most preferred hash that the counterparty supports
      * in pairing with the signature algorithm we want to use.
      */
      for(std::string hash : hashes)
         {
         for(auto algo : supported_algos)
            {
            if(algo.first == hash && algo.second == sig_algo)
               return hash;
            }
         }
      }

   // TLS v1.2 default hash if the counterparty sent nothing
   return "SHA-1";
   }

}

std::pair<std::string, Signature_Format>
Handshake_State::choose_sig_format(const Private_Key& key,
                                   std::string& hash_algo_out,
                                   std::string& sig_algo_out,
                                   bool for_client_auth,
                                   const Policy& policy) const
   {
   const std::string sig_algo = key.algo_name();

   std::vector<std::pair<std::string, std::string>> supported_algos =
      (for_client_auth) ? cert_req()->supported_algos() : client_hello()->supported_algos();

   const std::string hash_algo = choose_hash(sig_algo,
                                             supported_algos,
                                             this->version(),
                                             policy);

   if(this->version().supports_negotiable_signature_algorithms())
      {
      // We skip this check for v1.0 since you're stuck with SHA-1 regardless

      if(!policy.allowed_signature_hash(hash_algo))
         {
         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
                             "Policy refuses to accept signing with any hash supported by peer");
         }

      hash_algo_out = hash_algo;
      sig_algo_out = sig_algo;
      }

   if(sig_algo == "RSA")
      {
      const std::string padding = "EMSA3(" + hash_algo + ")";

      return std::make_pair(padding, IEEE_1363);
      }
   else if(sig_algo == "DSA" || sig_algo == "ECDSA")
      {
      const std::string padding = "EMSA1(" + hash_algo + ")";

      return std::make_pair(padding, DER_SEQUENCE);
      }

   throw Invalid_Argument(sig_algo + " is invalid/unknown for TLS signatures");
   }

namespace {

bool supported_algos_include(
   const std::vector<std::pair<std::string, std::string>>& algos,
   const std::string& key_type,
   const std::string& hash_type)
   {
   for(auto&& algo : algos)
      {
      if(algo.first == hash_type && algo.second == key_type)
         {
         return true;
         }
      }

   return false;
   }

}

std::pair<std::string, Signature_Format>
Handshake_State::parse_sig_format(const Public_Key& key,
                                  const std::string& input_hash_algo,
                                  const std::string& input_sig_algo,
                                  bool for_client_auth,
                                  const Policy& policy) const
   {
   const std::string key_type = key.algo_name();

   if(!policy.allowed_signature_method(key_type))
      {
      throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
                          "Rejecting " + key_type + " signature");
      }

   std::string hash_algo;

   if(this->version().supports_negotiable_signature_algorithms())
      {
      if(input_sig_algo != key_type)
         throw Decoding_Error("Counterparty sent inconsistent key and sig types");

      if(input_hash_algo == "")
         throw Decoding_Error("Counterparty did not send hash/sig IDS");

      hash_algo = input_hash_algo;

      if(for_client_auth && !cert_req())
         {
         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
                             "No certificate verify set");
         }

      /*
      Confirm the signature type we just received against the
      supported_algos list that we sent; it better be there.
      */

      const auto supported_algos =
         for_client_auth ? cert_req()->supported_algos() :
                           client_hello()->supported_algos();

      if(!supported_algos_include(supported_algos, key_type, hash_algo))
         {
         throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
                             "TLS signature extension did not allow for " +
                             key_type + "/" + hash_algo + " signature");
         }
      }
   else
      {
      if(input_hash_algo != "" || input_sig_algo != "")
         throw Decoding_Error("Counterparty sent hash/sig IDs with old version");

      if(key_type == "RSA")
         {
         hash_algo = "Parallel(MD5,SHA-160)";
         }
      else if(key_type == "DSA" || key_type == "ECDSA")
         {
         hash_algo = "SHA-1";
         }
      else
         {
         throw Invalid_Argument(key_type + " is invalid/unknown for TLS signatures");
         }

      /*
      There is no check on the acceptability of a v1.0/v1.1 hash type,
      since it's implicit with use of the protocol
      */
      }

   if(key_type == "RSA")
      {
      const std::string padding = "EMSA3(" + hash_algo + ")";
      return std::make_pair(padding, IEEE_1363);
      }
   else if(key_type == "DSA" || key_type == "ECDSA")
      {
      const std::string padding = "EMSA1(" + hash_algo + ")";
      return std::make_pair(padding, DER_SEQUENCE);
      }

   throw Invalid_Argument(key_type + " is invalid/unknown for TLS signatures");
   }

}

}
