/* -*- Mode:C++; c-file-style:"gnu"; indent-tabs-mode:nil; -*- */
/**
 * Copyright (c) 2013-2014 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.
 *
 * @author Yingdi Yu <http://irl.cs.ucla.edu/~yingdi/>
 * @author Jeff Thompson <jefft0@remap.ucla.edu>
 */

#include "common.hpp"

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

#include "cryptopp.hpp"

namespace ndn {

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)
{
}

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

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 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 PublicKey& key)
{
  const Name& interestName = interest.getName();

  if (interestName.size() < 2)
    return false;

  try
    {
      const Block& nameBlock = interestName.wireEncode();

      Signature sig(interestName[-2].blockFromValue(),
                    interestName[-1].blockFromValue());

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

      return verifySignature(nameBlock.value(),
                             nameBlock.value_size() - interestName[-1].size(),
                             sig, key);
    }
  catch (Block::Error& e)
    {
      return false;
    }
}

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

      switch (sig.getType())
        {
        case tlv::SignatureSha256WithRsa:
          {
            if (key.getKeyType() != KEY_TYPE_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() != KEY_TYPE_ECDSA)
              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, 64, 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, 96, 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 (CryptoPP::Exception& e)
    {
      return false;
    }
}

bool
Validator::verifySignature(const uint8_t* buf, const size_t size, const DigestSha256& sig)
{
  try
    {
      ConstBufferPtr buffer = crypto::sha256(buf, size);
      const Block& sigValue = sig.getValue();

      if (static_cast<bool>(buffer) &&
          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 (CryptoPP::Exception& e)
    {
      return false;
    }
}

void
Validator::onTimeout(const Interest& interest,
                     int remainingRetries,
                     const OnFailure& onFailure,
                     const shared_ptr<ValidationRequest>& validationRequest)
{
  if (remainingRetries > 0)
    // Issue the same expressInterest except decrement nRetrials.
    m_face->expressInterest(interest,
                            bind(&Validator::onData, this, _1, _2, 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 (std::vector<shared_ptr<ValidationRequest> >::const_iterator it = nextSteps.begin();
       it != nextSteps.end(); it++)
    {
      m_face->expressInterest((*it)->m_interest,
                              bind(&Validator::onData, this, _1, _2, *it),
                              bind(&Validator::onTimeout,
                                   this, _1, (*it)->m_nRetries,
                                   onFailure,
                                   *it));
    }
}

} // namespace ndn