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/*
* 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;
}
}
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