path: root/src/tls/c_hello.cpp

/*
* TLS Hello Request and Client Hello Messages
* (C) 2004-2011 Jack Lloyd
*
* Released under the terms of the Botan license
*/

#include <botan/internal/tls_messages.h>
#include <botan/internal/tls_reader.h>
#include <botan/internal/tls_session_key.h>
#include <botan/internal/tls_extensions.h>
#include <botan/tls_record.h>
#include <botan/internal/stl_util.h>
#include <botan/time.h>

namespace Botan {

namespace TLS {

MemoryVector<byte> make_hello_random(RandomNumberGenerator& rng)
   {
   MemoryVector<byte> buf(32);
   const u32bit time32 = system_time();
   store_be(time32, buf);
   rng.randomize(&buf[4], buf.size() - 4);
   return buf;
   }

/*
* Encode and send a Handshake message
*/
void Handshake_Message::send(Record_Writer& writer, Handshake_Hash& hash) const
   {
   MemoryVector<byte> buf = serialize();
   MemoryVector<byte> send_buf(4);

   const size_t buf_size = buf.size();

   send_buf[0] = type();

   for(size_t i = 1; i != 4; ++i)
     send_buf[i] = get_byte<u32bit>(i, buf_size);

   send_buf += buf;

   hash.update(send_buf);

   writer.send(HANDSHAKE, &send_buf[0], send_buf.size());
   }

/*
* Create a new Hello Request message
*/
Hello_Request::Hello_Request(Record_Writer& writer)
   {
   Handshake_Hash dummy; // FIXME: *UGLY*
   send(writer, dummy);
   }

/*
* Deserialize a Hello Request message
*/
Hello_Request::Hello_Request(const MemoryRegion<byte>& buf)
   {
   if(buf.size())
      throw Decoding_Error("Hello_Request: Must be empty, and is not");
   }

/*
* Serialize a Hello Request message
*/
MemoryVector<byte> Hello_Request::serialize() const
   {
   return MemoryVector<byte>();
   }

/*
* Create a new Client Hello message
*/
Client_Hello::Client_Hello(Record_Writer& writer,
                           Handshake_Hash& hash,
                           const Policy& policy,
                           RandomNumberGenerator& rng,
                           const MemoryRegion<byte>& reneg_info,
                           bool next_protocol,
                           const std::string& hostname,
                           const std::string& srp_identifier) :
   m_version(policy.pref_version()),
   m_random(make_hello_random(rng)),
   m_suites(policy.ciphersuite_list((srp_identifier != ""))),
   m_comp_methods(policy.compression()),
   m_hostname(hostname),
   m_srp_identifier(srp_identifier),
   m_next_protocol(next_protocol),
   m_fragment_size(0),
   m_secure_renegotiation(true),
   m_renegotiation_info(reneg_info)
   {
   std::vector<std::string> hashes = policy.allowed_hashes();
   std::vector<std::string> sigs = policy.allowed_signature_methods();

   for(size_t i = 0; i != hashes.size(); ++i)
      for(size_t j = 0; j != sigs.size(); ++j)
         m_supported_algos.push_back(std::make_pair(hashes[i], sigs[j]));

   send(writer, hash);
   }

/*
* Create a new Client Hello message
*/
Client_Hello::Client_Hello(Record_Writer& writer,
                           Handshake_Hash& hash,
                           RandomNumberGenerator& rng,
                           const Session& session,
                           bool next_protocol) :
   m_version(session.version()),
   m_session_id(session.session_id()),
   m_random(make_hello_random(rng)),
   m_hostname(session.sni_hostname()),
   m_srp_identifier(session.srp_identifier()),
   m_next_protocol(next_protocol),
   m_fragment_size(session.fragment_size()),
   m_secure_renegotiation(session.secure_renegotiation())
   {
   m_suites.push_back(session.ciphersuite());
   m_comp_methods.push_back(session.compression_method());

   // set m_supported_algos here?

   send(writer, hash);
   }

Client_Hello::Client_Hello(const MemoryRegion<byte>& buf, Handshake_Type type)
   {
   m_next_protocol = false;
   m_secure_renegotiation = false;
   m_fragment_size = 0;

   if(type == CLIENT_HELLO)
      deserialize(buf);
   else
      deserialize_sslv2(buf);
   }

/*
* Serialize a Client Hello message
*/
MemoryVector<byte> Client_Hello::serialize() const
   {
   MemoryVector<byte> buf;

   buf.push_back(m_version.major_version());
   buf.push_back(m_version.minor_version());
   buf += m_random;

   append_tls_length_value(buf, m_session_id, 1);
   append_tls_length_value(buf, m_suites, 2);
   append_tls_length_value(buf, m_comp_methods, 1);

   /*
   * May not want to send extensions at all in some cases.
   * If so, should include SCSV value (if reneg info is empty, if
   * not we are renegotiating with a modern server and should only
   * send that extension.
   */

   Extensions extensions;

   // Initial handshake
   if(m_renegotiation_info.empty())
      {
      extensions.add(new Renegotation_Extension(m_renegotiation_info));
      extensions.add(new Server_Name_Indicator(m_hostname));
      extensions.add(new SRP_Identifier(m_srp_identifier));

      if(m_version >= Protocol_Version::TLS_V12)
         extensions.add(new Signature_Algorithms(m_supported_algos));

      if(m_next_protocol)
         extensions.add(new Next_Protocol_Notification());
      }
   else
      {
      // renegotiation
      extensions.add(new Renegotation_Extension(m_renegotiation_info));
      }

   buf += extensions.serialize();

   return buf;
   }

void Client_Hello::deserialize_sslv2(const MemoryRegion<byte>& buf)
   {
   if(buf.size() < 12 || buf[0] != 1)
      throw Decoding_Error("Client_Hello: SSLv2 hello corrupted");

   const size_t cipher_spec_len = make_u16bit(buf[3], buf[4]);
   const size_t m_session_id_len = make_u16bit(buf[5], buf[6]);
   const size_t challenge_len = make_u16bit(buf[7], buf[8]);

   const size_t expected_size =
      (9 + m_session_id_len + cipher_spec_len + challenge_len);

   if(buf.size() != expected_size)
      throw Decoding_Error("Client_Hello: SSLv2 hello corrupted");

   if(m_session_id_len != 0 || cipher_spec_len % 3 != 0 ||
      (challenge_len < 16 || challenge_len > 32))
      {
      throw Decoding_Error("Client_Hello: SSLv2 hello corrupted");
      }

   for(size_t i = 9; i != 9 + cipher_spec_len; i += 3)
      {
      if(buf[i] != 0) // a SSLv2 cipherspec; ignore it
         continue;

      m_suites.push_back(make_u16bit(buf[i+1], buf[i+2]));
      }

   m_version = Protocol_Version(buf[1], buf[2]);

   m_random.resize(challenge_len);
   copy_mem(&m_random[0], &buf[9+cipher_spec_len+m_session_id_len], challenge_len);

   m_secure_renegotiation =
      value_exists(m_suites, static_cast<u16bit>(TLS_EMPTY_RENEGOTIATION_INFO_SCSV));
   }

/*
* Deserialize a Client Hello message
*/
void Client_Hello::deserialize(const MemoryRegion<byte>& buf)
   {
   if(buf.size() == 0)
      throw Decoding_Error("Client_Hello: Packet corrupted");

   if(buf.size() < 41)
      throw Decoding_Error("Client_Hello: Packet corrupted");

   TLS_Data_Reader reader(buf);

   const byte major_version = reader.get_byte();
   const byte minor_version = reader.get_byte();

   m_version = Protocol_Version(major_version, minor_version);

   m_random = reader.get_fixed<byte>(32);

   m_session_id = reader.get_range<byte>(1, 0, 32);

   m_suites = reader.get_range_vector<u16bit>(2, 1, 32767);

   m_comp_methods = reader.get_range_vector<byte>(1, 1, 255);

   Extensions extensions(reader);

   if(Server_Name_Indicator* sni = extensions.get<Server_Name_Indicator>())
      {
      m_hostname = sni->host_name();
      }

   if(SRP_Identifier* srp = extensions.get<SRP_Identifier>())
      {
      m_srp_identifier = srp->identifier();
      }

   if(Next_Protocol_Notification* npn = extensions.get<Next_Protocol_Notification>())
      {
      if(!npn->protocols().empty())
         throw Decoding_Error("Client sent non-empty NPN extension");

      m_next_protocol = true;
      }

   if(Maximum_Fragment_Length* frag = extensions.get<Maximum_Fragment_Length>())
      {
      m_fragment_size = frag->fragment_size();
      }

   if(Renegotation_Extension* reneg = extensions.get<Renegotation_Extension>())
      {
      // checked by Client / Server as they know the handshake state
      m_secure_renegotiation = true;
      m_renegotiation_info = reneg->renegotiation_info();
      }

   if(Signature_Algorithms* sigs = extensions.get<Signature_Algorithms>())
      {
      m_supported_algos = sigs->supported_signature_algorthms();
      }
   else
      {
      if(m_version >= Protocol_Version::TLS_V12)
         {
         /*
         The rule for when a TLS 1.2 client not sending the extension
         is strange; in theory, the server is supposed to act as if
         the client had sent only SHA-1 using whatever signature
         algorithm we end up negotiating. Right here, we don't know
         what we'll end up negotiating (depends on policy), but we do
         know that we'll only negotiate something the client sent, so
         we can safely say it supports everything here and know that
         we'll filter it out later.
         */
         m_supported_algos.push_back(std::make_pair("SHA-1", "RSA"));
         m_supported_algos.push_back(std::make_pair("SHA-1", "DSA"));
         m_supported_algos.push_back(std::make_pair("SHA-1", "ECDSA"));
         }
      else
         {
         // For versions before TLS 1.2, insert fake values for the old defaults

         m_supported_algos.push_back(std::make_pair("TLS.Digest.0", "RSA"));
         m_supported_algos.push_back(std::make_pair("SHA-1", "DSA"));
         m_supported_algos.push_back(std::make_pair("SHA-1", "ECDSA"));
         }
      }

   if(value_exists(m_suites, static_cast<u16bit>(TLS_EMPTY_RENEGOTIATION_INFO_SCSV)))
      {
      /*
      * Clients are allowed to send both the extension and the SCSV
      * though it is not recommended. If it did, require that the
      * extension value be empty.
      */
      if(m_secure_renegotiation)
         {
         if(!m_renegotiation_info.empty())
            {
            throw TLS_Exception(HANDSHAKE_FAILURE,
                                "Client send SCSV and non-empty extension");
            }
         }

      m_secure_renegotiation = true;
      m_renegotiation_info.clear();
      }
   }

/*
* Check if we offered this ciphersuite
*/
bool Client_Hello::offered_suite(u16bit ciphersuite) const
   {
   for(size_t i = 0; i != m_suites.size(); ++i)
      if(m_suites[i] == ciphersuite)
         return true;
   return false;
   }

}

}