tls_version.cpp

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/*
* TLS Protocol Version Management
* (C) 2012 Jack Lloyd
*     2021 Elektrobit Automotive GmbH
*     2022 René Meusel, Hannes Rantzsch - neXenio GmbH
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/tls_version.h>
 
#include <botan/tls_exceptn.h>
 
namespace Botan::TLS {
 
Protocol_Version Protocol_Version::latest_tls_version() {
#if defined(BOTAN_HAS_TLS_13)
   return Protocol_Version::TLS_V13;
#elif defined(BOTAN_HAS_TLS_12)
   return Protocol_Version::TLS_V12;
#else
   throw Not_Implemented("This build contains no usable TLS version");
#endif
}
 
Protocol_Version Protocol_Version::latest_dtls_version() {
#if defined(BOTAN_HAS_TLS_12)
   return Protocol_Version::DTLS_V12;
#else
   throw Not_Implemented("This build contains no usable DTLS version");
#endif
}
 
std::string Protocol_Version::to_string() const {
   const uint8_t maj = major_version();
   const uint8_t min = minor_version();
 
   if(maj == 3 && min == 0) {
      return "SSL v3";
   }
 
   if(maj == 3 && min >= 1) {  // TLS v1.x
      return "TLS v1." + std::to_string(min - 1);
   }
 
   if(maj == 254) {  // DTLS 1.x
      return "DTLS v1." + std::to_string(255 - min);
   }
 
   // Some very new or very old protocol (or bogus data)
   return "Unknown " + std::to_string(maj) + "." + std::to_string(min);
}
 
bool Protocol_Version::is_datagram_protocol() const {
   return major_version() > 250;
}
 
bool Protocol_Version::is_pre_tls_13() const {
   return (!is_datagram_protocol() && *this <= Protocol_Version::TLS_V12) ||
          (is_datagram_protocol() && *this <= Protocol_Version::DTLS_V12);
}
 
bool Protocol_Version::is_tls_13_or_later() const {
   return (!is_datagram_protocol() && *this >= Protocol_Version::TLS_V13) ||
          (is_datagram_protocol() && *this >= Protocol_Version::DTLS_V13);
}
 
bool Protocol_Version::operator>(const Protocol_Version& other) const {
   if(this->is_datagram_protocol() != other.is_datagram_protocol()) {
      throw TLS_Exception(Alert::ProtocolVersion, "Version comparing " + to_string() + " with " + other.to_string());
   }
 
   if(this->is_datagram_protocol()) {
      return m_version < other.m_version;  // goes backwards
   }
 
   return m_version > other.m_version;
}
 
bool Protocol_Version::valid() const {
   const uint8_t maj = major_version();
   const uint8_t min = minor_version();
 
   if(maj == 3 && min <= 4) {
      // 3.0: SSLv3
      // 3.1: TLS 1.0
      // 3.2: TLS 1.1
      // 3.3: TLS 1.2
      // 3.4: TLS 1.3
      return true;
   }
 
   if(maj == 254 && (min == 253 || min == 255)) {
      // 254.253: DTLS 1.2
      // 254.255: DTLS 1.0
      return true;
   }
 
   return false;
}
 
bool Protocol_Version::known_version() const {
#if defined(BOTAN_HAS_TLS_13)
   if(m_version == static_cast<uint16_t>(Protocol_Version::TLS_V13)) {
      return true;
   }
#endif
 
#if defined(BOTAN_HAS_TLS_12)
   if(m_version == static_cast<uint16_t>(Protocol_Version::TLS_V12)) {
      return true;
   }
   if(m_version == static_cast<uint16_t>(Protocol_Version::DTLS_V12)) {
      return true;
   }
#endif
 
   return false;
}
 
}  // namespace Botan::TLS