msg_certificate_12.cpp

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/*
* Certificate Message
* (C) 2004-2006,2012,2020 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/
 
#include <botan/tls_messages.h>
 
#include <botan/data_src.h>
#include <botan/tls_alert.h>
#include <botan/tls_exceptn.h>
#include <botan/tls_extensions.h>
#include <botan/internal/loadstor.h>
#include <botan/internal/tls_handshake_hash.h>
#include <botan/internal/tls_handshake_io.h>
 
namespace Botan::TLS {
 
/**
* Create a new Certificate message
*/
Certificate_12::Certificate_12(Handshake_IO& io, Handshake_Hash& hash, const std::vector<X509_Certificate>& cert_list) :
      m_certs(cert_list) {
   hash.update(io.send(*this));
}
 
/**
* Deserialize a Certificate message
*/
Certificate_12::Certificate_12(const std::vector<uint8_t>& buf, const Policy& policy) {
   if(buf.size() < 3) {
      throw Decoding_Error("Certificate: Message malformed");
   }
 
   const size_t total_size = make_uint32(0, buf[0], buf[1], buf[2]);
 
   if(total_size != buf.size() - 3) {
      throw Decoding_Error("Certificate: Message malformed");
   }
 
   const size_t max_size = policy.maximum_certificate_chain_size();
   if(max_size > 0 && total_size > max_size) {
      throw Decoding_Error("Certificate chain exceeds policy specified maximum size");
   }
 
   const uint8_t* certs = buf.data() + 3;
 
   while(size_t remaining_bytes = buf.data() + buf.size() - certs) {
      if(remaining_bytes < 3) {
         throw Decoding_Error("Certificate: Message malformed");
      }
 
      const size_t cert_size = make_uint32(0, certs[0], certs[1], certs[2]);
 
      if(remaining_bytes < (3 + cert_size)) {
         throw Decoding_Error("Certificate: Message malformed");
      }
 
      DataSource_Memory cert_buf(&certs[3], cert_size);
      m_certs.push_back(X509_Certificate(cert_buf));
 
      certs += cert_size + 3;
   }
 
   /*
   * TLS 1.0 through 1.2 all seem to require that the certificate be
   * precisely a v3 certificate. In fact the strict wording would seem
   * to require that every certificate in the chain be v3. But often
   * the intermediates are outside of the control of the server.
   * But, require that the leaf certificate be v3
   */
   if(!m_certs.empty() && m_certs[0].x509_version() != 3) {
      throw TLS_Exception(Alert::BadCertificate, "The leaf certificate must be v3");
   }
}
 
/**
* Serialize a Certificate message
*/
std::vector<uint8_t> Certificate_12::serialize() const {
   std::vector<uint8_t> buf(3);
 
   for(const auto& cert : m_certs) {
      const auto raw_cert = cert.BER_encode();
      const size_t cert_size = raw_cert.size();
      for(size_t j = 0; j != 3; ++j) {
         buf.push_back(get_byte_var(j + 1, static_cast<uint32_t>(cert_size)));
      }
      buf += raw_cert;
   }
 
   const size_t buf_size = buf.size() - 3;
   for(size_t i = 0; i != 3; ++i) {
      buf[i] = get_byte_var(i + 1, static_cast<uint32_t>(buf_size));
   }
 
   return buf;
}
 
}  // namespace Botan::TLS