path: root/src/lib/tls/msg_client_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_handshake_io.h>
#include <botan/internal/stl_util.h>
#include <chrono>

namespace Botan {

namespace TLS {

enum {
   TLS_EMPTY_RENEGOTIATION_INFO_SCSV        = 0x00FF,
   TLS_FALLBACK_SCSV                        = 0x5600
};

std::vector<byte> make_hello_random(RandomNumberGenerator& rng)
   {
   std::vector<byte> buf(32);

   const u32bit time32 = static_cast<u32bit>(
      std::chrono::system_clock::to_time_t(std::chrono::system_clock::now()));

   store_be(time32, &buf[0]);
   rng.randomize(&buf[4], buf.size() - 4);
   return buf;
   }

/*
* Create a new Hello Request message
*/
Hello_Request::Hello_Request(Handshake_IO& io)
   {
   io.send(*this);
   }

/*
* Deserialize a Hello Request message
*/
Hello_Request::Hello_Request(const std::vector<byte>& buf)
   {
   if(buf.size())
      throw Decoding_Error("Bad Hello_Request, has non-zero size");
   }

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

/*
* Create a new Client Hello message
*/
Client_Hello::Client_Hello(Handshake_IO& io,
                           Handshake_Hash& hash,
                           Protocol_Version version,
                           const Policy& policy,
                           RandomNumberGenerator& rng,
                           const std::vector<byte>& reneg_info,
                           bool next_protocol,
                           const std::string& hostname,
                           const std::string& srp_identifier) :
   m_version(version),
   m_random(make_hello_random(rng)),
   m_suites(policy.ciphersuite_list(m_version, (srp_identifier != ""))),
   m_comp_methods(policy.compression())
   {
   m_extensions.add(new Renegotiation_Extension(reneg_info));
   m_extensions.add(new SRP_Identifier(srp_identifier));
   m_extensions.add(new Server_Name_Indicator(hostname));
   m_extensions.add(new Session_Ticket());
   m_extensions.add(new Supported_Elliptic_Curves(policy.allowed_ecc_curves()));

   if(policy.negotiate_heartbeat_support())
      m_extensions.add(new Heartbeat_Support_Indicator(true));

   if(m_version.supports_negotiable_signature_algorithms())
      m_extensions.add(new Signature_Algorithms(policy.allowed_signature_hashes(),
                                                policy.allowed_signature_methods()));

   if(reneg_info.empty() && next_protocol)
      m_extensions.add(new Next_Protocol_Notification());

   BOTAN_ASSERT(policy.acceptable_protocol_version(version),
                "Our policy accepts the version we are offering");

   if(policy.send_fallback_scsv(version))
      m_suites.push_back(TLS_FALLBACK_SCSV);

   hash.update(io.send(*this));
   }

/*
* Create a new Client Hello message (session resumption case)
*/
Client_Hello::Client_Hello(Handshake_IO& io,
                           Handshake_Hash& hash,
                           const Policy& policy,
                           RandomNumberGenerator& rng,
                           const std::vector<byte>& reneg_info,
                           const Session& session,
                           bool next_protocol) :
   m_version(session.version()),
   m_session_id(session.session_id()),
   m_random(make_hello_random(rng)),
   m_suites(policy.ciphersuite_list(m_version, (session.srp_identifier() != ""))),
   m_comp_methods(policy.compression())
   {
   if(!value_exists(m_suites, session.ciphersuite_code()))
      m_suites.push_back(session.ciphersuite_code());

   if(!value_exists(m_comp_methods, session.compression_method()))
      m_comp_methods.push_back(session.compression_method());

   m_extensions.add(new Renegotiation_Extension(reneg_info));
   m_extensions.add(new SRP_Identifier(session.srp_identifier()));
   m_extensions.add(new Server_Name_Indicator(session.server_info().hostname()));
   m_extensions.add(new Session_Ticket(session.session_ticket()));
   m_extensions.add(new Supported_Elliptic_Curves(policy.allowed_ecc_curves()));

   if(policy.negotiate_heartbeat_support())
      m_extensions.add(new Heartbeat_Support_Indicator(true));

   if(session.fragment_size() != 0)
      m_extensions.add(new Maximum_Fragment_Length(session.fragment_size()));

   if(m_version.supports_negotiable_signature_algorithms())
      m_extensions.add(new Signature_Algorithms(policy.allowed_signature_hashes(),
                                                policy.allowed_signature_methods()));

   if(reneg_info.empty() && next_protocol)
      m_extensions.add(new Next_Protocol_Notification());

   hash.update(io.send(*this));
   }

/*
* Read a counterparty client hello
*/
Client_Hello::Client_Hello(const std::vector<byte>& buf, Handshake_Type type)
   {
   if(type == CLIENT_HELLO)
      deserialize(buf);
   else
      deserialize_sslv2(buf);
   }

void Client_Hello::update_hello_cookie(const Hello_Verify_Request& hello_verify)
   {
   if(!m_version.is_datagram_protocol())
      throw std::runtime_error("Cannot use hello cookie with stream protocol");

   m_hello_cookie = hello_verify.cookie();
   }

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

   if(m_version.is_datagram_protocol())
      append_tls_length_value(buf, m_hello_cookie, 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)
   */

   buf += m_extensions.serialize();

   return buf;
   }

void Client_Hello::deserialize_sslv2(const std::vector<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");
      }

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

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

   if(offered_suite(static_cast<u16bit>(TLS_EMPTY_RENEGOTIATION_INFO_SCSV)))
      m_extensions.add(new Renegotiation_Extension());
   }

/*
* Deserialize a Client Hello message
*/
void Client_Hello::deserialize(const std::vector<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("ClientHello", 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);

   if(m_version.is_datagram_protocol())
      m_hello_cookie = reader.get_range<byte>(1, 0, 255);

   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);

   m_extensions.deserialize(reader);

   if(offered_suite(static_cast<u16bit>(TLS_EMPTY_RENEGOTIATION_INFO_SCSV)))
      {
      if(Renegotiation_Extension* reneg = m_extensions.get<Renegotiation_Extension>())
         {
         if(!reneg->renegotiation_info().empty())
            throw TLS_Exception(Alert::HANDSHAKE_FAILURE,
                                "Client sent renegotiation SCSV and non-empty extension");
         }
      else
         {
         // add fake extension
         m_extensions.add(new Renegotiation_Extension());
         }
      }
   }

bool Client_Hello::sent_fallback_scsv() const
   {
   return offered_suite(static_cast<u16bit>(TLS_FALLBACK_SCSV));
   }

/*
* 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;
   }

}

}