/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2013-2017 Regents of the University of California.
 *
 * This file is part of ndn-cxx library (NDN C++ library with eXperimental eXtensions).
 *
 * ndn-cxx library is free software: you can redistribute it and/or modify it under the
 * terms of the GNU Lesser General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later version.
 *
 * ndn-cxx library is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
 * PARTICULAR PURPOSE.  See the GNU Lesser General Public License for more details.
 *
 * You should have received copies of the GNU General Public License and GNU Lesser
 * General Public License along with ndn-cxx, e.g., in COPYING.md file.  If not, see
 * <http://www.gnu.org/licenses/>.
 *
 * See AUTHORS.md for complete list of ndn-cxx authors and contributors.
 */

#include "validator.hpp"
#include "../util/crypto.hpp"
#include "../lp/tags.hpp"

#include "v1/cryptopp.hpp"

namespace ndn {
namespace security {

static Oid SECP256R1("1.2.840.10045.3.1.7");
static Oid SECP384R1("1.3.132.0.34");

Validator::Validator(Face* face)
  : m_face(face)
  , m_wantDirectCertFetch(false)
{
}

Validator::Validator(Face& face)
  : Validator(&face)
{
}

Validator::~Validator() = default;

void
Validator::validate(const Interest& interest,
                    const OnInterestValidated& onValidated,
                    const OnInterestValidationFailed& onValidationFailed,
                    int nSteps)
{
  std::vector<shared_ptr<ValidationRequest> > nextSteps;
  checkPolicy(interest, nSteps, onValidated, onValidationFailed, nextSteps);

  if (nextSteps.empty()) {
    // If there is no nextStep,
    // that means InterestPolicy has already been able to verify the Interest.
    // No more further processes.
    return;
  }

  OnFailure onFailure = bind(onValidationFailed, interest.shared_from_this(), _1);
  afterCheckPolicy(nextSteps, onFailure);
}

void
Validator::validate(const Data& data,
                    const OnDataValidated& onValidated,
                    const OnDataValidationFailed& onValidationFailed,
                    int nSteps)
{
  std::vector<shared_ptr<ValidationRequest> > nextSteps;
  checkPolicy(data, nSteps, onValidated, onValidationFailed, nextSteps);

  if (nextSteps.empty()) {
    // If there is no nextStep,
    // that means Data Policy has already been able to verify the Interest.
    // No more further processes.
    return;
  }

  OnFailure onFailure = bind(onValidationFailed, data.shared_from_this(), _1);
  afterCheckPolicy(nextSteps, onFailure);
}

void
Validator::onData(const Interest& interest,
                  const Data& data,
                  const shared_ptr<ValidationRequest>& nextStep)
{
  shared_ptr<const Data> certificateData = preCertificateValidation(data);

  if (!static_cast<bool>(certificateData))
    return nextStep->m_onDataValidationFailed(data.shared_from_this(),
                                              "Cannot decode cert: " + data.getName().toUri());

  validate(*certificateData,
           nextStep->m_onDataValidated, nextStep->m_onDataValidationFailed,
           nextStep->m_nSteps);
}

bool
Validator::verifySignature(const Data& data, const v1::PublicKey& key)
{
  if (!data.getSignature().hasKeyLocator())
    return false;

  return verifySignature(data.wireEncode().value(),
                         data.wireEncode().value_size() -
                         data.getSignature().getValue().size(),
                         data.getSignature(), key);
}

bool
Validator::verifySignature(const Interest& interest, const v1::PublicKey& key)
{
  const Name& name = interest.getName();

  if (name.size() < signed_interest::MIN_LENGTH_SIG_ONLY)
    return false;

  Signature sig;
  try {
    sig.setInfo(name[signed_interest::POS_SIG_INFO].blockFromValue());
    sig.setValue(name[signed_interest::POS_SIG_VALUE].blockFromValue());
  }
  catch (const tlv::Error&) {
    return false;
  }

  if (!sig.hasKeyLocator())
    return false;

  const Block& nameWire = name.wireEncode();
  return verifySignature(nameWire.value(),
                         nameWire.value_size() - name[signed_interest::POS_SIG_VALUE].size(),
                         sig, key);
}

bool
Validator::verifySignature(const uint8_t* buf,
                           const size_t size,
                           const Signature& sig,
                           const v1::PublicKey& key)
{
  try {
    using namespace CryptoPP;

    switch (sig.getType()) {
      case tlv::SignatureSha256WithRsa: {
        if (key.getKeyType() != KeyType::RSA)
          return false;

        RSA::PublicKey publicKey;
        ByteQueue queue;

        queue.Put(reinterpret_cast<const byte*>(key.get().buf()), key.get().size());
        publicKey.Load(queue);

        RSASS<PKCS1v15, SHA256>::Verifier verifier(publicKey);
        return verifier.VerifyMessage(buf, size,
                                      sig.getValue().value(), sig.getValue().value_size());
      }

      case tlv::SignatureSha256WithEcdsa: {
        if (key.getKeyType() != KeyType::EC)
          return false;

        ECDSA<ECP, SHA256>::PublicKey publicKey;
        ByteQueue queue;

        queue.Put(reinterpret_cast<const byte*>(key.get().buf()), key.get().size());
        publicKey.Load(queue);

        ECDSA<ECP, SHA256>::Verifier verifier(publicKey);

        uint32_t length = 0;
        StringSource src(key.get().buf(), key.get().size(), true);
        BERSequenceDecoder subjectPublicKeyInfo(src);
        {
          BERSequenceDecoder algorithmInfo(subjectPublicKeyInfo);
          {
            Oid algorithm;
            algorithm.decode(algorithmInfo);

            Oid curveId;
            curveId.decode(algorithmInfo);

            if (curveId == SECP256R1)
              length = 256;
            else if (curveId == SECP384R1)
              length = 384;
            else
              return false;
          }
        }

        switch (length) {
          case 256: {
            uint8_t buffer[64];
            size_t usedSize = DSAConvertSignatureFormat(buffer, sizeof(buffer), DSA_P1363,
                                                        sig.getValue().value(),
                                                        sig.getValue().value_size(),
                                                        DSA_DER);
            return verifier.VerifyMessage(buf, size, buffer, usedSize);
          }

          case 384: {
            uint8_t buffer[96];
            size_t usedSize = DSAConvertSignatureFormat(buffer, sizeof(buffer), DSA_P1363,
                                                        sig.getValue().value(),
                                                        sig.getValue().value_size(),
                                                        DSA_DER);
            return verifier.VerifyMessage(buf, size, buffer, usedSize);
          }

          default:
            return false;
        }
      }

      default:
        // Unsupported sig type
        return false;
    }
  }
  catch (const CryptoPP::Exception& e) {
    return false;
  }
}

bool
Validator::verifySignature(const uint8_t* buf, const size_t size, const DigestSha256& sig)
{
  try {
    ConstBufferPtr buffer = crypto::computeSha256Digest(buf, size);
    const Block& sigValue = sig.getValue();

    if (buffer != nullptr &&
        buffer->size() == sigValue.value_size() &&
        buffer->size() == crypto::SHA256_DIGEST_SIZE) {
      const uint8_t* p1 = buffer->buf();
      const uint8_t* p2 = sigValue.value();

      return 0 == memcmp(p1, p2, crypto::SHA256_DIGEST_SIZE);
    }
    else
      return false;
  }
  catch (const CryptoPP::Exception& e) {
    return false;
  }
}

void
Validator::onNack(const Interest& interest,
                  const lp::Nack& nack,
                  int remainingRetries,
                  const OnFailure& onFailure,
                  const shared_ptr<ValidationRequest>& validationRequest)
{
  if (remainingRetries > 0) {
    Interest newInterest = Interest(interest);
    newInterest.refreshNonce();

    //Express the same interest with different nonce and decremented remainingRetries.
    m_face->expressInterest(newInterest,
                            bind(&Validator::onData, this, _1, _2, validationRequest),
                            bind(&Validator::onNack, this, _1, _2,
                                 remainingRetries - 1, onFailure, validationRequest),
                            bind(&Validator::onTimeout, this, _1,
                                 remainingRetries - 1, onFailure, validationRequest));
  }
  else {
    onFailure("Cannot fetch cert: " + interest.getName().toUri());
  }
}

void
Validator::onTimeout(const Interest& interest,
                     int remainingRetries,
                     const OnFailure& onFailure,
                     const shared_ptr<ValidationRequest>& validationRequest)
{
  if (remainingRetries > 0) {
    Interest newInterest = Interest(interest);
    newInterest.refreshNonce();

    // Express the same interest with different nonce and decremented remainingRetries.
    m_face->expressInterest(newInterest,
                            bind(&Validator::onData, this, _1, _2, validationRequest),
                            bind(&Validator::onNack, this, _1, _2,
                                 remainingRetries - 1, onFailure, validationRequest),
                            bind(&Validator::onTimeout, this, _1,
                                 remainingRetries - 1, onFailure, validationRequest));
  }
  else {
    onFailure("Cannot fetch cert: " + interest.getName().toUri());
  }
}

void
Validator::afterCheckPolicy(const std::vector<shared_ptr<ValidationRequest>>& nextSteps,
                            const OnFailure& onFailure)
{
  if (m_face == nullptr) {
    onFailure("Require more information to validate the packet!");
    return;
  }

  for (shared_ptr<ValidationRequest> step : nextSteps) {
    if (m_wantDirectCertFetch && step->m_requesterFaceId != 0) {
      Interest directFetchInterest(step->m_interest);
      directFetchInterest.refreshNonce();
      directFetchInterest.setTag(make_shared<lp::NextHopFaceIdTag>(step->m_requesterFaceId));
      m_face->expressInterest(directFetchInterest, nullptr, nullptr, nullptr);
    }
    m_face->expressInterest(step->m_interest,
                            bind(&Validator::onData, this, _1, _2, step),
                            bind(&Validator::onNack, this, _1, _2,
                                 step->m_nRetries, onFailure, step),
                            bind(&Validator::onTimeout,
                                 this, _1, step->m_nRetries,
                                 onFailure,
                                 step));
  }
}

void
Validator::setDirectCertFetchEnabled(bool isEnabled)
{
  m_wantDirectCertFetch = isEnabled;
}

} // namespace security
} // namespace ndn