#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <boost/assign/std/vector.hpp> // for 'operator+=()'
#include <boost/assign/list_of.hpp>

#include <boost/format.hpp>
#include <p11-kit/p11-kit.h>

#include "pdns/dnssecinfra.hh"
#include "pdns/logger.hh"
#include "pdns/pdnsexception.hh"
#include "pdns/sha.hh"
#include "pdns/lock.hh"

#ifdef HAVE_LIBCRYPTO_ECDSA
#include <openssl/bn.h>
#include <openssl/ec.h>
#endif

#include "pkcs11signers.hh"
/* TODO

  - list possible tokens and supported modes
  - Engine: <name>, Slot: <slot>, PIN: <pin>
  - ECDSA support (how to test?)

NB! If you do use this, here is a simple way to get softhsm working

create /etc/pkcs11/modules/softhsm.module

put

module: /usr/lib/softhsm/libsofthsm.so
managed: yes

in it. you need to use softhsm tools to manage this all.

*/

#ifdef HAVE_P11KIT1_V2
static CK_FUNCTION_LIST** p11_modules;
#endif

#define ECDSA256_PARAMS "\x06\x08\x2a\x86\x48\xce\x3d\x03\x01\x07"
#define ECDSA384_PARAMS "\x06\x05\x2b\x81\x04\x00\x22"

// map for signing algorithms
static std::map<unsigned int,CK_MECHANISM_TYPE> dnssec2smech = boost::assign::map_list_of
(5, CKM_SHA1_RSA_PKCS)
(7, CKM_SHA1_RSA_PKCS)
(8, CKM_SHA256_RSA_PKCS)
(10, CKM_SHA512_RSA_PKCS)
(13, CKM_ECDSA)
(14, CKM_ECDSA);

// map for hashing algorithms
static std::map<unsigned int,CK_MECHANISM_TYPE> dnssec2hmech = boost::assign::map_list_of
(5, CKM_SHA_1)
(7, CKM_SHA_1)
(8, CKM_SHA256)
(10, CKM_SHA512)
(13, CKM_SHA256)
(14, CKM_SHA384);

static std::map<unsigned int,CK_MECHANISM_TYPE> dnssec2cmech = boost::assign::map_list_of
(5, CKM_RSA_PKCS_KEY_PAIR_GEN)
(7, CKM_RSA_PKCS_KEY_PAIR_GEN)
(8, CKM_RSA_PKCS_KEY_PAIR_GEN)
(10, CKM_RSA_PKCS_KEY_PAIR_GEN)
(13, CKM_ECDSA_KEY_PAIR_GEN)
(14, CKM_ECDSA_KEY_PAIR_GEN);

typedef enum { Attribute_Byte, Attribute_Long, Attribute_String } CkaValueType;

// Attribute handling
class P11KitAttribute {
private:
  CK_ATTRIBUTE_TYPE type;
  CK_BYTE ckByte;
  CK_ULONG ckLong;
  std::string ckString;
  CkaValueType ckType;
  std::unique_ptr<unsigned char[]> buffer;
  CK_ULONG buflen;
protected:
  void Init() {
    buflen = 0;
  };
public:
  P11KitAttribute(CK_ATTRIBUTE_TYPE type_, const std::string& value) {
    Init();
    this->type = type_;
    setString(value);
  }

  P11KitAttribute(CK_ATTRIBUTE_TYPE type_, char value) {
    Init();
    this->type = type_;
    setByte(value);
  }

  P11KitAttribute(CK_ATTRIBUTE_TYPE type_, unsigned char value) {
    Init();
    this->type = type_;
    setByte(value);
  }

  P11KitAttribute(CK_ATTRIBUTE_TYPE type_, unsigned long value) {
    Init();
    this->type = type_;
    setLong(value);
  }

  CkaValueType valueType() const {
    return ckType;
  }

  const std::string &str() const {
    return ckString;
  };

  unsigned char byte() const {
    return ckByte;
  }

  unsigned long ulong() const {
    return ckLong;
  }

  void setString(const std::string& value) {
    this->ckString = value;
    this->ckType = Attribute_String;
  }

  void setByte(char value) {
    this->ckByte = value;
    this->ckType = Attribute_Byte;
  }

  void setByte(unsigned char value) {
    this->ckByte = value;
    this->ckType = Attribute_Byte;
  }

  void setLong(unsigned long value) {
    this->ckLong = value;
    this->ckType = Attribute_Long;
  }

// this bit is used for getting attribute from object
// we provide a pointer for GetAttributeValue to write to
  CK_BYTE_PTR allocate(CK_ULONG amount) {
    buffer = std::make_unique<unsigned char[]>(amount);
    buflen = amount;
    return buffer.get();
  }

// and here we copy the results back and delete buffer
  void commit(CK_ULONG amount) {
    if (buffer) {
      this->ckString.assign((char*)buffer.get(), amount);
    }
    buffer.reset();
    buflen = 0;
  }

// this is *writable* attribute (you write into it)
  void wattr(CK_ATTRIBUTE_PTR attr) {
    attr->type = type;
    switch(ckType) {
      case Attribute_Byte: {
        attr->pValue = (void*)&ckByte;
        attr->ulValueLen = 1;
        break;
      }
      case Attribute_Long: {
        attr->pValue = (void*)&ckLong;
        attr->ulValueLen = sizeof(CK_ULONG);
        break;
      }
      case Attribute_String: {
        attr->pValue = buffer.get();
        attr->ulValueLen = buflen;
      }
    };
  };

// this is *readable* attribute (you read from it)
  void rattr(CK_ATTRIBUTE_PTR attr) const {
    attr->type = type;
    switch(ckType) {
      case Attribute_Byte: {
        attr->pValue = (void*)&ckByte;
        attr->ulValueLen = 1;
        break;
      }
      case Attribute_Long: {
        attr->pValue = (void*)&ckLong;
        attr->ulValueLen = sizeof(CK_ULONG);
        break;
      }
      case Attribute_String: {
        attr->pValue = (void*)ckString.c_str();
        attr->ulValueLen = ckString.size();
      }
    };
  };
};


class Pkcs11Slot {
  private:
    bool d_logged_in;
    CK_FUNCTION_LIST* d_functions; // module functions
    CK_SESSION_HANDLE d_session;
    CK_SLOT_ID d_slot;
    CK_RV d_err;

    void logError(const std::string& operation) const {
      if (d_err) {
        std::string msg = boost::str( boost::format("PKCS#11 operation %s failed: %s (0x%X) (%s)") % operation % p11_kit_strerror(d_err) % d_err % p11_kit_message() );
        g_log<<Logger::Error<< msg << endl;
      }
    }

  public:
  Pkcs11Slot(CK_FUNCTION_LIST* functions, const CK_SLOT_ID& slot) :
    d_logged_in(false),
    d_functions(functions),
    d_slot(slot),
    d_err(0)
  {
      CK_TOKEN_INFO tokenInfo;

      if ((d_err = d_functions->C_OpenSession(this->d_slot, CKF_SERIAL_SESSION|CKF_RW_SESSION, 0, 0, &(this->d_session)))) {
        logError("C_OpenSession");
        throw PDNSException("Could not open session");
      }
      // check if we need to login
      if ((d_err = d_functions->C_GetTokenInfo(d_slot, &tokenInfo)) == 0) {
        d_logged_in = !((tokenInfo.flags & CKF_LOGIN_REQUIRED) == CKF_LOGIN_REQUIRED);
      } else {
        logError("C_GetTokenInfo");
        throw PDNSException("Cannot get token info for slot " + std::to_string(slot));
      }
    }

    bool Login(const std::string& pin) {
      if (d_logged_in) return true;

      auto uPin = std::make_unique<unsigned char[]>(pin.size());
      memcpy(uPin.get(), pin.c_str(), pin.size());
      d_err = d_functions->C_Login(this->d_session, CKU_USER, uPin.get(), pin.size());
      memset(uPin.get(), 0, pin.size());
      logError("C_Login");

      if (d_err == 0) {
        d_logged_in = true;
      }

      return d_logged_in;
    }

    bool LoggedIn() const { return d_logged_in; }

    CK_SESSION_HANDLE& Session() { return d_session; }

    CK_FUNCTION_LIST* f() { return d_functions; }

    static std::shared_ptr<LockGuarded<Pkcs11Slot>> GetSlot(const std::string& module, const string& tokenId);
    static CK_RV HuntSlot(const string& tokenId, CK_SLOT_ID &slotId, _CK_SLOT_INFO* info, CK_FUNCTION_LIST* functions);
};

class Pkcs11Token {
  private:
    std::shared_ptr<LockGuarded<Pkcs11Slot>> d_slot;

    CK_OBJECT_HANDLE d_public_key;
    CK_OBJECT_HANDLE d_private_key;
    CK_KEY_TYPE d_key_type;

    CK_ULONG d_bits;
    std::string d_exponent;
    std::string d_modulus;
    std::string d_ec_point;
    std::string d_ecdsa_params;

    std::string d_label;
    std::string d_pub_label;

    bool d_loaded;
    CK_RV d_err;

    void logError(const std::string& operation) const {
      if (d_err) {
        std::string msg = boost::str( boost::format("PKCS#11 operation %s failed: %s (0x%X) (%s)") % operation % p11_kit_strerror(d_err) % d_err % p11_kit_message());
        g_log<<Logger::Error<< msg << endl;
      }
    }

    unsigned int ecparam2bits(const std::string& obj) const {
      // if we can use some library to parse the EC parameters, better use it.
      // otherwise fall back to using hardcoded primev256 and secp384r1
#ifdef HAVE_LIBCRYPTO_ECDSA
      unsigned int bits = 0;
      const unsigned char *in = reinterpret_cast<const unsigned char*>(obj.c_str());
      auto order = std::unique_ptr<BIGNUM, void(*)(BIGNUM*)>(BN_new(), BN_clear_free);
      auto tempKey = d2i_ECParameters(nullptr, &in, obj.size());
      if (tempKey != nullptr) {
        auto key = std::unique_ptr<EC_KEY, void(*)(EC_KEY*)>(tempKey, EC_KEY_free);
        tempKey = nullptr;
        if (EC_GROUP_get_order(EC_KEY_get0_group(key.get()), order.get(), nullptr) == 1) {
          bits = BN_num_bits(order.get());
        }
      }

      if (bits == 0)
        throw PDNSException("Unsupported EC key");

      return bits;
#else
      if (d_ecdsa_params == ECDSA256_PARAMS) return 256;
      else if (d_ecdsa_params == ECDSA384_PARAMS) return 384;
      else throw PDNSException("Unsupported EC key");
#endif
    }

  public:
    Pkcs11Token(const std::shared_ptr<LockGuarded<Pkcs11Slot>>& slot, const std::string& label, const std::string& pub_label);
    ~Pkcs11Token();

    bool Login(const std::string& pin) {
      if (pin.empty()) return false; // no empty pin.
      if (d_slot->lock()->Login(pin) == true) {
        LoadAttributes();
      }

      return LoggedIn();
    }

    bool LoggedIn() {
      if (d_loaded == false && d_slot->lock()->LoggedIn() == true) {
        LoadAttributes();
      }
      return d_slot->lock()->LoggedIn();
    }

    void LoadAttributes() {
      auto slot = d_slot->lock();
      std::vector<P11KitAttribute> attr;
      std::vector<CK_OBJECT_HANDLE> key;
      attr.push_back(P11KitAttribute(CKA_CLASS, (unsigned long)CKO_PRIVATE_KEY));
//      attr.push_back(P11KitAttribute(CKA_SIGN, (char)CK_TRUE));
      attr.push_back(P11KitAttribute(CKA_LABEL, d_label));
      FindObjects2(*slot, attr, key, 1);
      if (key.size() == 0) {
        g_log<<Logger::Warning<<"Cannot load PCKS#11 private key "<<d_label<<std::endl;;
        return;
      }
      d_private_key = key[0];
      attr.clear();
      attr.push_back(P11KitAttribute(CKA_CLASS, (unsigned long)CKO_PUBLIC_KEY));
//      attr.push_back(P11KitAttribute(CKA_VERIFY, (char)CK_TRUE));
      attr.push_back(P11KitAttribute(CKA_LABEL, d_pub_label));
      FindObjects2(*slot, attr, key, 1);
      if (key.size() == 0) {
        g_log<<Logger::Warning<<"Cannot load PCKS#11 public key "<<d_pub_label<<std::endl;
        return;
      }
      d_public_key = key[0];

      attr.clear();
      attr.push_back(P11KitAttribute(CKA_KEY_TYPE, 0UL));

      if (GetAttributeValue2(*slot, d_public_key, attr)==0) {
        d_key_type = attr[0].ulong();
        if (d_key_type == CKK_RSA) {
          attr.clear();
          attr.push_back(P11KitAttribute(CKA_MODULUS, ""));
          attr.push_back(P11KitAttribute(CKA_PUBLIC_EXPONENT, ""));
          attr.push_back(P11KitAttribute(CKA_MODULUS_BITS, 0UL));

          if (!GetAttributeValue2(*slot, d_public_key, attr)) {
            d_modulus = attr[0].str();
            d_exponent = attr[1].str();
            d_bits = attr[2].ulong();
          } else {
            throw PDNSException("Cannot load attributes for PCKS#11 public key " + d_pub_label);
          }
        } else if (d_key_type == CKK_EC || d_key_type == CKK_ECDSA) {
          attr.clear();
          attr.push_back(P11KitAttribute(CKA_ECDSA_PARAMS, ""));
          attr.push_back(P11KitAttribute(CKA_EC_POINT, ""));
          if (!GetAttributeValue2(*slot, d_public_key, attr)) {
            d_ecdsa_params = attr[0].str();
            d_bits = ecparam2bits(d_ecdsa_params);
            if (attr[1].str().length() != (d_bits*2/8 + 3)) throw PDNSException("EC Point data invalid");
            d_ec_point = attr[1].str().substr(3);
          } else {
            throw PDNSException("Cannot load attributes for PCKS#11 public key " + d_pub_label);
          }
        } else {
          throw PDNSException("Cannot determine type for PCKS#11 public key " + d_pub_label);
        }
      } else {
        throw PDNSException("Cannot load attributes for PCKS#11 public key " + d_pub_label);
      }

      d_loaded = true;
    }

    int GenerateKeyPair(CK_MECHANISM_PTR mechanism, std::vector<P11KitAttribute>& pubAttributes, std::vector<P11KitAttribute>& privAttributes, CK_OBJECT_HANDLE_PTR pubKey, CK_OBJECT_HANDLE_PTR privKey) {
      {
      auto slot = d_slot->lock();

      size_t k;
      auto pubAttr = std::make_unique<CK_ATTRIBUTE[]>(pubAttributes.size());
      auto privAttr = std::make_unique<CK_ATTRIBUTE[]>(pubAttributes.size());

      k = 0;
      for(P11KitAttribute& attribute :  pubAttributes) {
        attribute.rattr(pubAttr.get()+k);
        k++;
      }

      k = 0;
      for(P11KitAttribute& attribute :  privAttributes) {
        attribute.rattr(privAttr.get()+k);
        k++;
      }

      d_err = slot->f()->C_GenerateKeyPair(slot->Session(), mechanism, pubAttr.get(), pubAttributes.size(), privAttr.get(), privAttributes.size(), pubKey, privKey);
      logError("C_GenerateKeyPair");
      }

      if (d_err == 0) LoadAttributes();

      return d_err;
    }

    int Sign(const std::string& data, std::string& result, CK_MECHANISM_PTR mechanism) {
      CK_BYTE buffer[1024];
      CK_ULONG buflen = sizeof buffer; // should be enough for most signatures.
      auto slot = d_slot->lock();

      // perform signature
      if ((d_err = slot->f()->C_SignInit(slot->Session(), mechanism, d_private_key))) { logError("C_SignInit"); return d_err; }
      d_err = slot->f()->C_Sign(slot->Session(), (unsigned char*)data.c_str(), data.size(), buffer, &buflen);

      if (!d_err) {
        result.assign((char*)buffer, buflen);
      }

      memset(buffer,0,sizeof buffer);
      logError("C_Sign");
      return d_err;
    }

    int Verify(const std::string& data, const std::string& signature, CK_MECHANISM_PTR mechanism) {
      auto slot = d_slot->lock();

      if ((d_err = slot->f()->C_VerifyInit(slot->Session(), mechanism, d_public_key))) { logError("C_VerifyInit"); return d_err; }
      d_err = slot->f()->C_Verify(slot->Session(), (unsigned char*)data.c_str(), data.size(), (unsigned char*)signature.c_str(), signature.size());
      logError("C_Verify");
      return d_err;
    }

    int Digest(const std::string& data, std::string& result, CK_MECHANISM_PTR mechanism) {
      CK_BYTE buffer[1024];
      CK_ULONG buflen = sizeof buffer; // should be enough for most digests

      auto slot = d_slot->lock();
      if ((d_err = slot->f()->C_DigestInit(slot->Session(), mechanism))) { logError("C_DigestInit"); return d_err; }
      d_err = slot->f()->C_Digest(slot->Session(), (unsigned char*)data.c_str(), data.size(), buffer, &buflen);
      if (!d_err) {
        result.assign((char*)buffer, buflen);
      }
      memset(buffer,0,sizeof buffer);
      logError("C_Digest");
      return d_err;
    }

    int DigestInit(Pkcs11Slot& slot, CK_MECHANISM_PTR mechanism) {
      d_err = slot.f()->C_DigestInit(slot.Session(), mechanism);
      logError("C_DigestInit");
      return d_err;
    }

    int DigestUpdate(Pkcs11Slot& slot, const std::string& data) {
      d_err = slot.f()->C_DigestUpdate(slot.Session(), (unsigned char*)data.c_str(), data.size());
      logError("C_DigestUpdate");
      return d_err;
    }

    int DigestKey(std::string& result) {
      auto slot = d_slot->lock();
      CK_MECHANISM mech;
      mech.mechanism = CKM_SHA_1;

      DigestInit(*slot, &mech);

      if (d_key_type == CKK_RSA) {
        DigestUpdate(*slot, d_modulus);
        DigestUpdate(*slot, d_exponent);
      } else if (d_key_type == CKK_EC || d_key_type == CKK_ECDSA) {
        DigestUpdate(*slot, d_ec_point);
      }

      DigestFinal(*slot, result);

      return d_err;
    }

    int DigestFinal(Pkcs11Slot& slot, std::string& result) {
      CK_BYTE buffer[1024] = {0};
      CK_ULONG buflen = sizeof buffer; // should be enough for most digests

      d_err = slot.f()->C_DigestFinal(slot.Session(), buffer, &buflen);
      if (!d_err) {
        result.assign((char*)buffer, buflen);
      }
      memset(buffer,0,sizeof buffer);
      logError("C_DigestFinal");
      return d_err;
    }

    int FindObjects2(Pkcs11Slot& slot, const std::vector<P11KitAttribute>& attributes, std::vector<CK_OBJECT_HANDLE>& objects, int maxobjects) {
      CK_RV rv;
      size_t k;
      unsigned long count;

      auto handles = std::make_unique<CK_OBJECT_HANDLE[]>(maxobjects);
      auto attr = std::make_unique<CK_ATTRIBUTE[]>(attributes.size());

      k = 0;
      for(const P11KitAttribute& attribute :  attributes) {
        attribute.rattr(attr.get()+k);
        k++;
      }

      // perform search
      d_err = slot.f()->C_FindObjectsInit(slot.Session(), attr.get(), k);

      if (d_err) {
        logError("C_FindObjectsInit");
        return d_err;
      }

      count = maxobjects;
      rv = d_err = slot.f()->C_FindObjects(slot.Session(), handles.get(), maxobjects, &count);
      objects.clear();

      if (!rv) {
        for(k=0;k<count;k++) {
          objects.push_back((handles.get())[k]);
        }
      }

      logError("C_FindObjects");

      d_err = slot.f()->C_FindObjectsFinal(slot.Session());
      logError("C_FindObjectsFinal");

      return rv;
    }

    int GetAttributeValue2(Pkcs11Slot& slot, const CK_OBJECT_HANDLE& object, std::vector<P11KitAttribute>& attributes)
    {
      size_t k;
      auto attr = std::make_unique<CK_ATTRIBUTE[]>(attributes.size());

      k = 0;
      for(P11KitAttribute &attribute :  attributes) {
        attribute.wattr(attr.get()+k);
        k++;
      }

      // round 1 - get attribute sizes
      d_err = slot.f()->C_GetAttributeValue(slot.Session(), object, attr.get(), attributes.size());
      logError("C_GetAttributeValue");
      if (d_err) {
        return d_err;
      }

      // then allocate memory
      for(size_t idx=0; idx < attributes.size(); idx++) {
        if (attributes[idx].valueType() == Attribute_String) {
          (attr.get())[idx].pValue = attributes[idx].allocate((attr.get())[idx].ulValueLen);
        }
      }

      // round 2 - get actual values
      d_err = slot.f()->C_GetAttributeValue(slot.Session(), object, attr.get(), attributes.size());
      logError("C_GetAttributeValue");

      // copy values to map and release allocated memory
      for(size_t idx=0; idx < attributes.size(); idx++) {
        if (attributes[idx].valueType() == Attribute_String) {
          attributes[idx].commit((attr.get())[idx].ulValueLen);
        }
      }

      return d_err;
    };

    const std::string& Modulus() {
      return d_modulus;
    }

    const std::string& Exponent() {
      return d_exponent;
    }

    const std::string& ECPoint() {
      return d_ec_point;
    }

    const std::string& ECParameters() {
      return d_ecdsa_params;
    }

    CK_KEY_TYPE KeyType() {
      return d_key_type;
    }

    CK_ULONG Bits() {
      return d_bits;
    }

    static std::shared_ptr<Pkcs11Token> GetToken(const std::string& module, const string& tokenId, const std::string& label, const std::string& pub_label);
};

static std::map<std::string, std::shared_ptr<LockGuarded<Pkcs11Slot> > > pkcs11_slots;
static std::map<std::string, std::shared_ptr<Pkcs11Token> > pkcs11_tokens;

CK_RV Pkcs11Slot::HuntSlot(const string& tokenId, CK_SLOT_ID &slotId, _CK_SLOT_INFO* info, CK_FUNCTION_LIST* functions)
{
  CK_RV err;
  unsigned int i;
  unsigned long slots;
  _CK_TOKEN_INFO tinfo;

  // go thru all slots
  // this is required by certain tokens, otherwise C_GetSlotInfo will not return a token
  err = functions->C_GetSlotList(CK_FALSE, NULL_PTR, &slots);
  if (err) {
    g_log<<Logger::Warning<<"C_GetSlotList(CK_FALSE, NULL_PTR, &slots) = " << err << std::endl;
    return err;
  }

  // get the actual slot ids
  std::vector<CK_SLOT_ID> slotIds(slots);
  err = functions->C_GetSlotList(CK_FALSE, slotIds.data(), &slots);
  if (err) {
    g_log<<Logger::Warning<<"C_GetSlotList(CK_FALSE, slotIds, &slots) = " << err << std::endl;
    return err;
  }

  // iterate all slots
  for(i=0;i<slots;i++) {
    slotId=slotIds[i];
    if (slotId == static_cast<CK_SLOT_ID>(-1))
      continue;
    if ((err = functions->C_GetSlotInfo(slotId, info))) {
      g_log<<Logger::Warning<<"C_GetSlotList("<<slotId<<", info) = " << err << std::endl;
      return err;
    }
    if ((err = functions->C_GetTokenInfo(slotId, &tinfo))) {
      g_log<<Logger::Warning<<"C_GetSlotList("<<slotId<<", &tinfo) = " << err << std::endl;
      return err;
    }
    std::string slotName;
    slotName.assign(reinterpret_cast<char*>(tinfo.label), 32);
    // trim it
    boost::trim(slotName);

    if (boost::iequals(slotName, tokenId)) {
      return 0;
    }
  }

  // see if we can find it with slotId
  try {
    slotId = std::stoi(tokenId);
    if ((err = functions->C_GetSlotInfo(slotId, info))) {
      g_log<<Logger::Warning<<"C_GetSlotList("<<slotId<<", info) = " << err << std::endl;
      return err;
    }
    g_log<<Logger::Warning<<"Specifying PKCS#11 token by SLOT ID is deprecated and should not be used"<<std::endl;
    return 0;
  } catch (...) {
    return CKR_SLOT_ID_INVALID;
  }
  return CKR_SLOT_ID_INVALID;
}

std::shared_ptr<LockGuarded<Pkcs11Slot>> Pkcs11Slot::GetSlot(const std::string& module, const string& tokenId) {
  // see if we can find module
  std::string sidx = module;
  sidx.append("|");
  sidx.append(tokenId);
  std::map<std::string, std::shared_ptr<LockGuarded<Pkcs11Slot> > >::iterator slotIter;
  CK_RV err;
  CK_FUNCTION_LIST* functions;

  // see if we have slot
  if ((slotIter = pkcs11_slots.find(sidx)) != pkcs11_slots.end()) {
    return slotIter->second;
  }

#ifdef HAVE_P11KIT1_V2
  functions = p11_kit_module_for_name(p11_modules, module.c_str());
#else
  functions = p11_kit_registered_name_to_module(module.c_str());
#endif
  if (functions == nullptr) throw PDNSException("Cannot find PKCS#11 module " + module);
  functions->C_Initialize(nullptr); // initialize the module in case it hasn't been done yet.

  // try to locate a slot
   _CK_SLOT_INFO info;
  CK_SLOT_ID slotId;

  if ((err = Pkcs11Slot::HuntSlot(tokenId, slotId, &info, functions))) {
    throw PDNSException(std::string("Cannot find PKCS#11 token ") + tokenId + std::string(" on module ") + module + std::string(": ") + boost::str( boost::format("%s (0x%X)") % p11_kit_strerror(err) % err));
  }

  // store slot
  pkcs11_slots[sidx] = std::make_shared<LockGuarded<Pkcs11Slot>>(Pkcs11Slot(functions, slotId));

  return pkcs11_slots[sidx];
}

std::shared_ptr<Pkcs11Token> Pkcs11Token::GetToken(const std::string& module, const string& tokenId, const std::string& label, const std::string& pub_label) {
  // see if we can find module
  std::string tidx = module;
  tidx.append("|");
  tidx.append(tokenId);
  tidx.append("|");
  tidx.append(label);
  std::map<std::string, std::shared_ptr<Pkcs11Token> >::iterator tokenIter;
  if ((tokenIter = pkcs11_tokens.find(tidx)) != pkcs11_tokens.end()) return tokenIter->second;

  std::shared_ptr<LockGuarded<Pkcs11Slot>> slot = Pkcs11Slot::GetSlot(module, tokenId);
  pkcs11_tokens[tidx] = std::make_shared<Pkcs11Token>(slot, label, pub_label);
  return pkcs11_tokens[tidx];
}

Pkcs11Token::Pkcs11Token(const std::shared_ptr<LockGuarded<Pkcs11Slot>>& slot, const std::string& label, const std::string& pub_label) :
  d_slot(slot),
  d_bits(0),
  d_label(label),
  d_pub_label(pub_label),
  d_loaded(false),
  d_err(0)
{
  // open a session
  if (this->d_slot->lock()->LoggedIn()) LoadAttributes();
}

Pkcs11Token::~Pkcs11Token() {
}

bool PKCS11ModuleSlotLogin(const std::string& module, const string& tokenId, const std::string& pin)
{
  std::shared_ptr<LockGuarded<Pkcs11Slot>> slot = Pkcs11Slot::GetSlot(module, tokenId);
  if (slot->lock()->LoggedIn()) return true; // no point failing
  return slot->lock()->Login(pin);
}

PKCS11DNSCryptoKeyEngine::PKCS11DNSCryptoKeyEngine(unsigned int algorithm): DNSCryptoKeyEngine(algorithm) {}
PKCS11DNSCryptoKeyEngine::~PKCS11DNSCryptoKeyEngine() {}
PKCS11DNSCryptoKeyEngine::PKCS11DNSCryptoKeyEngine(const PKCS11DNSCryptoKeyEngine& orig) : DNSCryptoKeyEngine(orig.d_algorithm) {}

void PKCS11DNSCryptoKeyEngine::create(unsigned int bits) {
  std::vector<P11KitAttribute> pubAttr;
  std::vector<P11KitAttribute> privAttr;
  CK_MECHANISM mech;
  CK_OBJECT_HANDLE pubKey, privKey;
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  std::string pubExp("\000\001\000\001", 4); // 65537

  try {
    mech.mechanism = dnssec2cmech.at(d_algorithm);
  } catch (std::out_of_range& e) {
    throw PDNSException("pkcs11: unsupported algorithm "+std::to_string(d_algorithm)+ " for key pair generation");
  }

  mech.pParameter = nullptr;
  mech.ulParameterLen = 0;

  if (mech.mechanism == CKM_RSA_PKCS_KEY_PAIR_GEN) {
    pubAttr.push_back(P11KitAttribute(CKA_CLASS, (unsigned long)CKO_PUBLIC_KEY));
    pubAttr.push_back(P11KitAttribute(CKA_KEY_TYPE, (unsigned long)CKK_RSA));
    pubAttr.push_back(P11KitAttribute(CKA_TOKEN, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_ENCRYPT, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_VERIFY, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_WRAP, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_MODULUS_BITS, (unsigned long)bits));
    pubAttr.push_back(P11KitAttribute(CKA_PUBLIC_EXPONENT, pubExp));
    pubAttr.push_back(P11KitAttribute(CKA_LABEL, d_pub_label));

    privAttr.push_back(P11KitAttribute(CKA_CLASS, (unsigned long)CKO_PRIVATE_KEY));
    privAttr.push_back(P11KitAttribute(CKA_KEY_TYPE, (unsigned long)CKK_RSA));
    privAttr.push_back(P11KitAttribute(CKA_TOKEN, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_PRIVATE, (char)CK_TRUE));
  //  privAttr.push_back(P11KitAttribute(CKA_SUBJECT, "CN=keygen"));
    privAttr.push_back(P11KitAttribute(CKA_ID, "\x01\x02\x03\x04")); // this is mandatory if you want to export anything
    privAttr.push_back(P11KitAttribute(CKA_SENSITIVE, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_DECRYPT, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_SIGN, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_UNWRAP, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_LABEL, d_label));
  } else if (mech.mechanism == CKM_ECDSA_KEY_PAIR_GEN) {
    pubAttr.push_back(P11KitAttribute(CKA_CLASS, (unsigned long)CKO_PUBLIC_KEY));
    pubAttr.push_back(P11KitAttribute(CKA_KEY_TYPE, (unsigned long)CKK_ECDSA));
    pubAttr.push_back(P11KitAttribute(CKA_TOKEN, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_ENCRYPT, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_VERIFY, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_WRAP, (char)CK_TRUE));
    pubAttr.push_back(P11KitAttribute(CKA_LABEL, d_pub_label));
    if (d_algorithm == 13) pubAttr.push_back(P11KitAttribute(CKA_ECDSA_PARAMS, ECDSA256_PARAMS));
    else if (d_algorithm == 14) pubAttr.push_back(P11KitAttribute(CKA_ECDSA_PARAMS, ECDSA384_PARAMS));
    else throw PDNSException("pkcs11: unknown algorithm "+std::to_string(d_algorithm)+" for ECDSA key pair generation");

    privAttr.push_back(P11KitAttribute(CKA_CLASS, (unsigned long)CKO_PRIVATE_KEY));
    privAttr.push_back(P11KitAttribute(CKA_KEY_TYPE, (unsigned long)CKK_ECDSA));
    privAttr.push_back(P11KitAttribute(CKA_TOKEN, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_PRIVATE, (char)CK_TRUE));
  //  privAttr.push_back(P11KitAttribute(CKA_SUBJECT, "CN=keygen"));
    privAttr.push_back(P11KitAttribute(CKA_ID, "\x01\x02\x03\x04")); // this is mandatory if you want to export anything
    privAttr.push_back(P11KitAttribute(CKA_SENSITIVE, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_DECRYPT, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_SIGN, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_UNWRAP, (char)CK_TRUE));
    privAttr.push_back(P11KitAttribute(CKA_LABEL, d_label));
  } else {
    throw PDNSException("pkcs11: don't know how make key for algorithm "+std::to_string(d_algorithm));
  }


  if (d_slot->GenerateKeyPair(&mech, pubAttr, privAttr, &pubKey, &privKey)) {
    throw PDNSException("Keypair generation failed");
  }
};

std::string PKCS11DNSCryptoKeyEngine::sign(const std::string& msg) const {
  std::string result;
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  CK_MECHANISM mech;
  mech.mechanism = dnssec2smech[d_algorithm];
  mech.pParameter = nullptr;
  mech.ulParameterLen = 0;

  if (mech.mechanism == CKM_ECDSA) {
    if (d_slot->Sign(this->hash(msg), result, &mech)) throw PDNSException("Could not sign data");
  } else {
    if (d_slot->Sign(msg, result, &mech)) throw PDNSException("Could not sign data");
  }
  return result;
};

std::string PKCS11DNSCryptoKeyEngine::hash(const std::string& msg) const {
  std::string result;
  CK_MECHANISM mech;
  mech.mechanism = dnssec2hmech[d_algorithm];
  mech.pParameter = nullptr;
  mech.ulParameterLen = 0;
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  if (d_slot->Digest(msg, result, &mech)) {
    g_log<<Logger::Error<<"Could not digest using PKCS#11 token - using software workaround"<<endl;
    // FINE! I'll do this myself, then, shall I?
    switch(d_algorithm) {
    case 5: {
      return pdns_sha1sum(msg);
    }
    case 8: {
      return pdns_sha256sum(msg);
    }
    case 10: {
      return pdns_sha512sum(msg);
    }
    case 13: {
      return pdns_sha256sum(msg);
    }
    case 14: {
      return pdns_sha384sum(msg);
    }
    };
  };
  return result;
};

bool PKCS11DNSCryptoKeyEngine::verify(const std::string& msg, const std::string& signature) const {
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  CK_MECHANISM mech;
  mech.mechanism = dnssec2smech[d_algorithm];
  mech.pParameter = nullptr;
  mech.ulParameterLen = 0;
  if (mech.mechanism == CKM_ECDSA) {
    return (d_slot->Verify(this->hash(msg), signature, &mech)==0);
  } else {
    return (d_slot->Verify(msg, signature, &mech) == 0);
  }
};

std::string PKCS11DNSCryptoKeyEngine::getPubKeyHash() const {
  // find us a public key
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  std::string result;
  if (d_slot->DigestKey(result) == 0) return result;
  throw PDNSException("Could not digest key (maybe it's missing?)");
};

std::string PKCS11DNSCryptoKeyEngine::getPublicKeyString() const {
  std::string result("");
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  if (d_slot->KeyType() == CKK_RSA) {
    if (d_slot->Exponent().length() < 255) {
      result.assign(1, (char) (unsigned int) d_slot->Exponent().length());
    } else {
      result.assign(1, 0);
      uint16_t len=htons(d_slot->Exponent().length());
      result.append((char*)&len, 2);
    }
    result.append(d_slot->Exponent());
    result.append(d_slot->Modulus());
  } else {
    result.append(d_slot->ECPoint());
  }
  return result;
};

int PKCS11DNSCryptoKeyEngine::getBits() const {
  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Not logged in to token");

  return d_slot->Bits();
};

DNSCryptoKeyEngine::storvector_t PKCS11DNSCryptoKeyEngine::convertToISCVector() const {
  auto storvect = storvector_t{
    {"Algorithm", std::to_string(d_algorithm)},
    {"Engine", d_module},
    {"Slot", d_slot_id},
    {"PIN", d_pin},
    {"Label", d_label},
    {"PubLabel", d_pub_label},
  };
  return storvect;
};

void PKCS11DNSCryptoKeyEngine::fromISCMap(DNSKEYRecordContent& drc, stormap_t& stormap) {
  pdns::checked_stoi_into(drc.d_algorithm, stormap["algorithm"]);
  d_module = stormap["engine"];
  d_slot_id = stormap["slot"];
  boost::trim(d_slot_id);
  d_pin = stormap["pin"];
  d_label = stormap["label"];
  if (stormap.find("publabel") != stormap.end())
    d_pub_label = stormap["publabel"];
  else
    d_pub_label = d_label;
  // validate parameters

  std::shared_ptr<Pkcs11Token> d_slot;
  d_slot = Pkcs11Token::GetToken(d_module, d_slot_id, d_label, d_pub_label);
  if (d_pin != "" && d_slot->LoggedIn() == false)
    if (d_slot->Login(d_pin) == false)
      throw PDNSException("Could not log in to token (PIN wrong?)");
};

std::unique_ptr<DNSCryptoKeyEngine> PKCS11DNSCryptoKeyEngine::maker(unsigned int algorithm)
{
  return make_unique<PKCS11DNSCryptoKeyEngine>(algorithm);
}

// this is called during program startup
namespace {
  static struct LoaderStruct
  {
    LoaderStruct()
    {
#ifdef HAVE_P11KIT1_V2
      p11_modules = p11_kit_modules_load_and_initialize(0);
#else
      p11_kit_initialize_registered();
#endif
    };
    ~LoaderStruct() {
#ifdef HAVE_P11KIT1_V2
      p11_kit_modules_release(p11_modules);
#else
      p11_kit_finalize_registered();
#endif
    };
  } loaderPkcs11;
}
