/*
* X.509 CRL
* (C) 1999-2007 Jack Lloyd
*
* Botan is released under the Simplified BSD License (see license.txt)
*/

#include <botan/x509_crl.h>
#include <botan/x509_ext.h>
#include <botan/x509cert.h>
#include <botan/ber_dec.h>

#include <sstream>

namespace Botan {

struct CRL_Data
   {
   X509_DN m_issuer;
   X509_Time m_this_update;
   X509_Time m_next_update;
   std::vector<CRL_Entry> m_entries;
   Extensions m_extensions;

   // cached values from extensions
   size_t m_crl_number = 0;
   std::vector<uint8_t> m_auth_key_id;
   std::string m_issuing_distribution_point;
   };

std::string X509_CRL::PEM_label() const
   {
   return "X509 CRL";
   }

std::vector<std::string> X509_CRL::alternate_PEM_labels() const
   {
   return { "CRL" };
   }

X509_CRL::X509_CRL(DataSource& src)
   {
   load_data(src);
   }

X509_CRL::X509_CRL(const std::vector<uint8_t>& vec)
   {
   DataSource_Memory src(vec.data(), vec.size());
   load_data(src);
   }

#if defined(BOTAN_TARGET_OS_HAS_FILESYSTEM)
X509_CRL::X509_CRL(const std::string& fsname)
   {
   DataSource_Stream src(fsname, true);
   load_data(src);
   }
#endif

X509_CRL::X509_CRL(const X509_DN& issuer,
                   const X509_Time& this_update,
                   const X509_Time& next_update,
                   const std::vector<CRL_Entry>& revoked) :
   X509_Object()
   {
   m_data.reset(new CRL_Data);
   m_data->m_issuer = issuer;
   m_data->m_this_update = this_update;
   m_data->m_next_update = next_update;
   m_data->m_entries = revoked;
   }

/**
* Check if this particular certificate is listed in the CRL
*/
bool X509_CRL::is_revoked(const X509_Certificate& cert) const
   {
   /*
   If the cert wasn't issued by the CRL issuer, it's possible the cert
   is revoked, but not by this CRL. Maybe throw an exception instead?
   */
   if(cert.issuer_dn() != issuer_dn())
      return false;

   std::vector<uint8_t> crl_akid = authority_key_id();
   std::vector<uint8_t> cert_akid = cert.authority_key_id();

   if(!crl_akid.empty() && !cert_akid.empty())
      {
      if(crl_akid != cert_akid)
         return false;
      }

   std::vector<uint8_t> cert_serial = cert.serial_number();

   bool is_revoked = false;

   // FIXME would be nice to avoid a linear scan here - maybe sort the entries?
   for(const CRL_Entry& entry : get_revoked())
      {
      if(cert_serial == entry.serial_number())
         {
         if(entry.reason_code() == REMOVE_FROM_CRL)
            is_revoked = false;
         else
            is_revoked = true;
         }
      }

   return is_revoked;
   }

/*
* Decode the TBSCertList data
*/
namespace {

std::unique_ptr<CRL_Data> decode_crl_body(const std::vector<uint8_t>& body,
                                          const AlgorithmIdentifier& sig_algo)
   {
   std::unique_ptr<CRL_Data> data(new CRL_Data);

   BER_Decoder tbs_crl(body);

   size_t version;
   tbs_crl.decode_optional(version, INTEGER, UNIVERSAL);

   if(version != 0 && version != 1)
      throw X509_CRL::X509_CRL_Error("Unknown X.509 CRL version " +
                           std::to_string(version+1));

   AlgorithmIdentifier sig_algo_inner;
   tbs_crl.decode(sig_algo_inner);

   if(sig_algo != sig_algo_inner)
      throw X509_CRL::X509_CRL_Error("Algorithm identifier mismatch");

   tbs_crl.decode(data->m_issuer)
      .decode(data->m_this_update)
      .decode(data->m_next_update);

   BER_Object next = tbs_crl.get_next_object();

   if(next.is_a(SEQUENCE, CONSTRUCTED))
      {
      BER_Decoder cert_list(next);

      while(cert_list.more_items())
         {
         CRL_Entry entry;
         cert_list.decode(entry);
         data->m_entries.push_back(entry);
         }
      next = tbs_crl.get_next_object();
      }

   if(next.is_a(0, ASN1_Tag(CONSTRUCTED | CONTEXT_SPECIFIC)))
      {
      BER_Decoder crl_options(next);
      crl_options.decode(data->m_extensions).verify_end();
      next = tbs_crl.get_next_object();
      }

   if(next.is_set())
      throw X509_CRL::X509_CRL_Error("Unknown tag in CRL");

   tbs_crl.verify_end();

   // Now cache some fields from the extensions
   if(auto ext = data->m_extensions.get_extension_object_as<Cert_Extension::CRL_Number>())
      {
      data->m_crl_number = ext->get_crl_number();
      }
   if(auto ext = data->m_extensions.get_extension_object_as<Cert_Extension::Authority_Key_ID>())
      {
      data->m_auth_key_id = ext->get_key_id();
      }
   if(auto ext = data->m_extensions.get_extension_object_as<Cert_Extension::CRL_Issuing_Distribution_Point>())
      {
      std::stringstream ss;

      for(const auto& pair : ext->get_point().contents())
         {
         ss << pair.first << ": " << pair.second << " ";
         }
      data->m_issuing_distribution_point = ss.str();
      }

   return data;
   }

}

void X509_CRL::force_decode()
   {
   m_data.reset(decode_crl_body(signed_body(), signature_algorithm()).release());
   }

const CRL_Data& X509_CRL::data() const
   {
   if(!m_data)
      {
      throw Invalid_State("X509_CRL uninitialized");
      }
   return *m_data.get();
   }

const Extensions& X509_CRL::extensions() const
   {
   return data().m_extensions;
   }

/*
* Return the list of revoked certificates
*/
const std::vector<CRL_Entry>& X509_CRL::get_revoked() const
   {
   return data().m_entries;
   }

/*
* Return the distinguished name of the issuer
*/
const X509_DN& X509_CRL::issuer_dn() const
   {
   return data().m_issuer;
   }

/*
* Return the key identifier of the issuer
*/
const std::vector<uint8_t>& X509_CRL::authority_key_id() const
   {
   return data().m_auth_key_id;
   }

/*
* Return the CRL number of this CRL
*/
uint32_t X509_CRL::crl_number() const
   {
   return data().m_crl_number;
   }

/*
* Return the issue data of the CRL
*/
const X509_Time& X509_CRL::this_update() const
   {
   return data().m_this_update;
   }

/*
* Return the date when a new CRL will be issued
*/
const X509_Time& X509_CRL::next_update() const
   {
   return data().m_next_update;
   }

/*
* Return the CRL's distribution point
*/
std::string X509_CRL::crl_issuing_distribution_point() const
   {
   return data().m_issuing_distribution_point;
   }
}