msg_cert_req.cpp

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/*
* Certificate Request Message
* (C) 2004-2006,2012 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_messages.h>
#include <botan/tls_extensions.h>
#include <botan/internal/tls_reader.h>
#include <botan/internal/tls_handshake_io.h>
#include <botan/internal/tls_handshake_hash.h>
#include <botan/der_enc.h>
#include <botan/ber_dec.h>
 
namespace Botan::TLS {
 
Handshake_Type Certificate_Request_12::type() const
   {
   return Handshake_Type::CertificateRequest;
   }
 
namespace {
 
std::string cert_type_code_to_name(uint8_t code)
   {
   switch(code)
      {
      case 1:
         return "RSA";
      case 64:
         return "ECDSA";
      default:
         return ""; // DH or something else
      }
   }
 
uint8_t cert_type_name_to_code(std::string_view name)
   {
   if(name == "RSA")
      return 1;
   if(name == "ECDSA")
      return 64;
 
   throw Invalid_Argument(fmt("Unknown/unhandled TLS cert type {}", name));
   }
 
}
 
/**
* Create a new Certificate Request message
*/
Certificate_Request_12::Certificate_Request_12(Handshake_IO& io,
                                 Handshake_Hash& hash,
                                 const Policy& policy,
                                 const std::vector<X509_DN>& ca_certs) :
   m_names(ca_certs),
   m_cert_key_types({ "RSA", "ECDSA" })
   {
   m_schemes = policy.acceptable_signature_schemes();
   hash.update(io.send(*this));
   }
 
/**
* Deserialize a Certificate Request message
*/
Certificate_Request_12::Certificate_Request_12(const std::vector<uint8_t>& buf)
   {
   if(buf.size() < 4)
      throw Decoding_Error("Certificate_Req: Bad certificate request");
 
   TLS_Data_Reader reader("CertificateRequest", buf);
 
   const auto cert_type_codes = reader.get_range_vector<uint8_t>(1, 1, 255);
 
   for(const auto cert_type_code : cert_type_codes)
      {
      const std::string cert_type_name = cert_type_code_to_name(cert_type_code);
 
      if(cert_type_name.empty()) // something we don't know
         continue;
 
      m_cert_key_types.emplace_back(cert_type_name);
      }
 
   const std::vector<uint8_t> algs = reader.get_range_vector<uint8_t>(2, 2, 65534);
 
   if(algs.size() % 2 != 0)
      throw Decoding_Error("Bad length for signature IDs in certificate request");
 
   for(size_t i = 0; i != algs.size(); i += 2)
      {
      m_schemes.emplace_back(make_uint16(algs[i], algs[i+1]));
      }
 
   const uint16_t purported_size = reader.get_uint16_t();
 
   if(reader.remaining_bytes() != purported_size)
      throw Decoding_Error("Inconsistent length in certificate request");
 
   while(reader.has_remaining())
      {
      std::vector<uint8_t> name_bits = reader.get_range_vector<uint8_t>(2, 0, 65535);
 
      BER_Decoder decoder(name_bits.data(), name_bits.size());
      X509_DN name;
      decoder.decode(name);
      m_names.emplace_back(name);
      }
   }
 
const std::vector<std::string>& Certificate_Request_12::acceptable_cert_types() const
   {
   return m_cert_key_types;
   }
 
const std::vector<X509_DN>& Certificate_Request_12::acceptable_CAs() const
   {
   return m_names;
   }
 
const std::vector<Signature_Scheme>& Certificate_Request_12::signature_schemes() const
   {
   return m_schemes;
   }
 
/**
* Serialize a Certificate Request message
*/
std::vector<uint8_t> Certificate_Request_12::serialize() const
   {
   std::vector<uint8_t> buf;
 
   std::vector<uint8_t> cert_types;
 
   cert_types.reserve(m_cert_key_types.size());
   for(const auto& cert_key_type : m_cert_key_types)
      cert_types.push_back(cert_type_name_to_code(cert_key_type));
 
   append_tls_length_value(buf, cert_types, 1);
 
   if(!m_schemes.empty())
      buf += Signature_Algorithms(m_schemes).serialize(Connection_Side::Server);
 
   std::vector<uint8_t> encoded_names;
 
   for(const auto& name : m_names)
      {
      DER_Encoder encoder;
      encoder.encode(name);
 
      append_tls_length_value(encoded_names, encoder.get_contents(), 2);
      }
 
   append_tls_length_value(buf, encoded_names, 2);
 
   return buf;
   }
}