/*
* TLS Cipher Suite
* (C) 2004-2010,2012,2013 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/tls_ciphersuite.h>
#include <botan/parsing.h>
#include <botan/block_cipher.h>
#include <botan/stream_cipher.h>
#include <botan/hash.h>
#include <botan/mac.h>
#include <sstream>
#include <stdexcept>

namespace Botan {

namespace TLS {

namespace {

/*
* This way all work happens at the constuctor call, and we can
* rely on that happening only once in C++11.
*/
std::vector<Ciphersuite> gather_known_ciphersuites()
   {
   std::vector<Ciphersuite> ciphersuites;

   for(size_t i = 0; i <= 0xFFFF; ++i)
      {
      Ciphersuite suite = Ciphersuite::by_id(i);

      if(suite.valid())
         ciphersuites.push_back(suite);
      }

   return ciphersuites;
   }

}

const std::vector<Ciphersuite>& Ciphersuite::all_known_ciphersuites()
   {
   static std::vector<Ciphersuite> all_ciphersuites(gather_known_ciphersuites());
   return all_ciphersuites;
   }

Ciphersuite Ciphersuite::by_name(const std::string& name)
   {
   for(auto suite : all_known_ciphersuites())
      {
      if(suite.to_string() == name)
         return suite;
      }

   return Ciphersuite(); // some unknown ciphersuite
   }

bool Ciphersuite::is_scsv(u16bit suite)
   {
   // TODO: derive from IANA file in script
   return (suite == 0x00FF || suite == 0x5600);
   }

Ciphersuite::Ciphersuite(u16bit ciphersuite_code,
                         const char* sig_algo,
                         const char* kex_algo,
                         const char* cipher_algo,
                         size_t cipher_keylen,
                         size_t nonce_bytes_from_handshake,
                         size_t nonce_bytes_from_record,
                         const char* mac_algo,
                         size_t mac_keylen,
                         const char* prf_algo) :
   m_ciphersuite_code(ciphersuite_code),
   m_sig_algo(sig_algo),
   m_kex_algo(kex_algo),
   m_prf_algo(prf_algo),
   m_cipher_algo(cipher_algo),
   m_cipher_keylen(cipher_keylen),
   m_nonce_bytes_from_handshake(nonce_bytes_from_handshake),
   m_nonce_bytes_from_record(nonce_bytes_from_record),
   m_mac_algo(mac_algo),
   m_mac_keylen(mac_keylen)
   {
   }

bool Ciphersuite::psk_ciphersuite() const
   {
   return (kex_algo() == "PSK" ||
           kex_algo() == "DHE_PSK" ||
           kex_algo() == "ECDHE_PSK");
   }

bool Ciphersuite::ecc_ciphersuite() const
   {
   return (sig_algo() == "ECDSA" || kex_algo() == "ECDH" || kex_algo() == "ECDHE_PSK");
   }

namespace {

bool have_hash(const std::string& prf)
   {
   return (HashFunction::providers(prf).size() > 0);
   }

bool have_cipher(const std::string& cipher)
   {
   return (BlockCipher::providers(cipher).size() > 0) ||
      (StreamCipher::providers(cipher).size() > 0);
   }

}

bool Ciphersuite::valid() const
   {
   if(!m_cipher_keylen) // uninitialized object
      return false;

   if(!have_hash(prf_algo()))
      return false;

   if(mac_algo() == "AEAD")
      {
      if(cipher_algo() == "ChaCha20Poly1305")
         {
#if !defined(BOTAN_HAS_AEAD_CHACHA20_POLY1305)
         return false;
#endif
         }
      else
         {
         auto cipher_and_mode = split_on(cipher_algo(), '/');
         BOTAN_ASSERT(cipher_and_mode.size() == 2, "Expected format for AEAD algo");
         if(!have_cipher(cipher_and_mode[0]))
            return false;

         const auto mode = cipher_and_mode[1];

#if !defined(BOTAN_HAS_AEAD_CCM)
         if(mode == "CCM" || mode == "CCM-8")
            return false;
#endif

#if !defined(BOTAN_HAS_AEAD_GCM)
         if(mode == "GCM")
            return false;
#endif

#if !defined(BOTAN_HAS_AEAD_OCB)
         if(mode == "OCB(12)" || mode == "OCB")
            return false;
#endif
         }
      }
   else
      {
      // Old non-AEAD schemes
      if(!have_cipher(cipher_algo()))
         return false;
      if(!have_hash(mac_algo())) // HMAC
         return false;
      }

   if(kex_algo() == "SRP_SHA")
      {
#if !defined(BOTAN_HAS_SRP6)
      return false;
#endif
      }
   else if(kex_algo() == "ECDH" || kex_algo() == "ECDHE_PSK")
      {
#if !defined(BOTAN_HAS_ECDH)
      return false;
#endif
      }
   else if(kex_algo() == "DH" || kex_algo() == "DHE_PSK")
      {
#if !defined(BOTAN_HAS_DIFFIE_HELLMAN)
      return false;
#endif
      }

   if(sig_algo() == "DSA")
      {
#if !defined(BOTAN_HAS_DSA)
      return false;
#endif
      }
   else if(sig_algo() == "ECDSA")
      {
#if !defined(BOTAN_HAS_ECDSA)
      return false;
#endif
      }
   else if(sig_algo() == "RSA")
      {
#if !defined(BOTAN_HAS_RSA)
      return false;
#endif
      }

   return true;
   }

std::string Ciphersuite::to_string() const
   {
   if(m_cipher_keylen == 0)
      throw std::runtime_error("Ciphersuite::to_string - no value set");

   std::ostringstream out;

   out << "TLS_";

   if(kex_algo() != "RSA")
      {
      if(kex_algo() == "DH")
         out << "DHE";
      else if(kex_algo() == "ECDH")
         out << "ECDHE";
      else
         out << kex_algo();

      out << '_';
      }

   if(sig_algo() == "DSA")
      out << "DSS_";
   else if(sig_algo() != "")
      out << sig_algo() << '_';

   out << "WITH_";

   if(cipher_algo() == "RC4")
      {
      out << "RC4_128_";
      }
   else if(cipher_algo() == "ChaCha20Poly1305")
      {
      out << "CHACHA20_POLY1305_";
      }
   else
      {
      if(cipher_algo() == "3DES")
         out << "3DES_EDE";
      else if(cipher_algo().find("Camellia") == 0)
         out << "CAMELLIA_" << std::to_string(8*cipher_keylen());
      else
         {
         if(cipher_algo().find("OCB(12)") != std::string::npos)
            out << replace_chars(cipher_algo().substr(0, cipher_algo().size() - 4),
                                 {'-', '/'}, '_');
         else
            out << replace_chars(cipher_algo(), {'-', '/'}, '_');
         }

      if(cipher_algo().find("/") != std::string::npos)
         out << "_"; // some explicit mode already included
      else
         out << "_CBC_";
      }

   if(mac_algo() == "SHA-1")
      out << "SHA";
   else if(mac_algo() == "AEAD")
      out << erase_chars(prf_algo(), {'-'});
   else
      out << erase_chars(mac_algo(), {'-'});

   return out.str();
   }

}

}