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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "RootCertificateTelemetryUtils.h"

#include "mozilla/Logging.h"
#include "RootHashes.inc" // Note: Generated by genRootCAHashes.js
#include "ScopedNSSTypes.h"
#include "mozilla/ArrayUtils.h"

namespace mozilla { namespace psm {

mozilla::LazyLogModule gPublicKeyPinningTelemetryLog("PublicKeyPinningTelemetryService");

// Used in the BinarySearch method, this does a memcmp between the pointer
// provided to its construtor and whatever the binary search is looking for.
//
// This implementation assumes everything to be of HASH_LEN, so it should not
// be used generically.
class BinaryHashSearchArrayComparator
{
public:
  explicit BinaryHashSearchArrayComparator(const uint8_t* aTarget, size_t len)
    : mTarget(aTarget)
  {
    MOZ_ASSERT(len == HASH_LEN, "Hashes should be of the same length.");
  }

  int operator()(const CertAuthorityHash val) const {
    return memcmp(mTarget, val.hash, HASH_LEN);
  }

private:
  const uint8_t* mTarget;
};

// Perform a hash of the provided cert, then search in the RootHashes.inc data
// structure for a matching bin number.
int32_t
RootCABinNumber(const SECItem* cert)
{
  Digest digest;

  // Compute SHA256 hash of the certificate
  nsresult rv = digest.DigestBuf(SEC_OID_SHA256, cert->data, cert->len);
  if (NS_WARN_IF(NS_FAILED(rv))) {
    return ROOT_CERTIFICATE_HASH_FAILURE;
  }

  // Compare against list of stored hashes
  size_t idx;

  MOZ_LOG(gPublicKeyPinningTelemetryLog, LogLevel::Debug,
           ("pkpinTelem: First bytes %02x %02x %02x %02x\n",
            digest.get().data[0], digest.get().data[1], digest.get().data[2], digest.get().data[3]));

  if (mozilla::BinarySearchIf(ROOT_TABLE, 0, ArrayLength(ROOT_TABLE),
        BinaryHashSearchArrayComparator(static_cast<uint8_t*>(digest.get().data),
                                        digest.get().len),
        &idx)) {

    MOZ_LOG(gPublicKeyPinningTelemetryLog, LogLevel::Debug,
          ("pkpinTelem: Telemetry index was %zu, bin is %d\n",
           idx, ROOT_TABLE[idx].binNumber));
    return (int32_t) ROOT_TABLE[idx].binNumber;
  }

  // Didn't match.
  return ROOT_CERTIFICATE_UNKNOWN;
}


// Attempt to increment the appropriate bin in the provided Telemetry probe ID. If
// there was a hash failure, we do nothing.
void
AccumulateTelemetryForRootCA(mozilla::Telemetry::HistogramID probe,
  const CERTCertificate* cert)
{
  int32_t binId = RootCABinNumber(&cert->derCert);

  if (binId != ROOT_CERTIFICATE_HASH_FAILURE) {
    Accumulate(probe, binId);
  }
}

} // namespace psm
} // namespace mozilla