/* -*- 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/. */

#ifndef mozilla_dom_SRICheck_h
#define mozilla_dom_SRICheck_h

#include "nsTString.h"
#include "nsStringFwd.h"
#include "nsCOMPtr.h"
#include "nsICryptoHash.h"

class nsIChannel;
class nsIConsoleReportCollector;

namespace mozilla::dom {

class SRIMetadata;

class SRICheck final {
 public:
  static const uint32_t MAX_METADATA_LENGTH = 24 * 1024;
  static const uint32_t MAX_METADATA_TOKENS = 512;

  /**
   * Parse the multiple hashes specified in the integrity attribute and
   * return the strongest supported hash.
   */
  static nsresult IntegrityMetadata(const nsAString& aMetadataList,
                                    const nsACString& aSourceFileURI,
                                    nsIConsoleReportCollector* aReporter,
                                    SRIMetadata* outMetadata);
};

// The SRICheckDataVerifier can be used in 2 different mode:
//
// 1. The streaming mode involves reading bytes from an input, and to use
//    the |Update| function to stream new bytes, and to use the |Verify|
//    function to check the hash of the content with the hash provided by
//    the metadata.
//
//    Optionally, one can serialize the verified hash with |ExportDataSummary|,
//    in a buffer in order to rely on the second mode the next time.
//
// 2. The pre-computed mode, involves reading a hash with |ImportDataSummary|,
//    which got exported by the SRICheckDataVerifier and potentially cached, and
//    then use the |Verify| function to check against the hash provided by the
//    metadata.
class SRICheckDataVerifier final {
 public:
  SRICheckDataVerifier(const SRIMetadata& aMetadata,
                       const nsACString& aSourceFileURI,
                       nsIConsoleReportCollector* aReporter);

  // Append the following bytes to the content used to compute the hash. Once
  // all bytes are streamed, use the Verify function to check the integrity.
  nsresult Update(uint32_t aStringLen, const uint8_t* aString);

  // Verify that the computed hash corresponds to the metadata.
  nsresult Verify(const SRIMetadata& aMetadata, nsIChannel* aChannel,
                  const nsACString& aSourceFileURI,
                  nsIConsoleReportCollector* aReporter);

  bool IsComplete() const { return mComplete; }

  // Report the length of the computed hash and its type, such that we can
  // reserve the space for encoding it in a vector.
  uint32_t DataSummaryLength();
  static uint32_t EmptyDataSummaryLength();

  // Write the computed hash and its type in a pre-allocated buffer.
  nsresult ExportDataSummary(uint32_t aDataLen, uint8_t* aData);
  static nsresult ExportEmptyDataSummary(uint32_t aDataLen, uint8_t* aData);

  // Report the length of the computed hash and its type, such that we can
  // skip these data while reading a buffer.
  static nsresult DataSummaryLength(uint32_t aDataLen, const uint8_t* aData,
                                    uint32_t* length);

  // Extract the computed hash and its type, such that we can |Verify| if it
  // matches the metadata. The buffer should be at least the same size or
  // larger than the value returned by |DataSummaryLength|.
  nsresult ImportDataSummary(uint32_t aDataLen, const uint8_t* aData);

 private:
  nsCOMPtr<nsICryptoHash> mCryptoHash;
  nsAutoCString mComputedHash;
  size_t mBytesHashed;
  uint32_t mHashLength;
  int8_t mHashType;
  bool mInvalidMetadata;
  bool mComplete;

  nsresult EnsureCryptoHash();
  nsresult Finish();
  nsresult VerifyHash(const SRIMetadata& aMetadata, uint32_t aHashIndex,
                      const nsACString& aSourceFileURI,
                      nsIConsoleReportCollector* aReporter);
};

}  // namespace mozilla::dom

#endif  // mozilla_dom_SRICheck_h