// Copyright 2014 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef THIRD_PARTY_BLINK_RENDERER_PLATFORM_LOADER_SUBRESOURCE_INTEGRITY_H_
#define THIRD_PARTY_BLINK_RENDERER_PLATFORM_LOADER_SUBRESOURCE_INTEGRITY_H_

#include <string_view>

#include "base/gtest_prod_util.h"
#include "base/types/expected.h"
#include "services/network/public/mojom/fetch_api.mojom-blink.h"
#include "services/network/public/mojom/integrity_algorithm.mojom-blink.h"
#include "third_party/blink/renderer/platform/crypto.h"
#include "third_party/blink/renderer/platform/loader/fetch/integrity_metadata.h"
#include "third_party/blink/renderer/platform/platform_export.h"
#include "third_party/blink/renderer/platform/wtf/allocator/allocator.h"
#include "third_party/blink/renderer/platform/wtf/text/wtf_string.h"
#include "third_party/blink/renderer/platform/wtf/vector.h"

namespace blink {

class FeatureContext;
class IntegrityReport;
class KURL;
class Resource;

using network::mojom::blink::FetchResponseType;

class PLATFORM_EXPORT SubresourceIntegrity final {
  STATIC_ONLY(SubresourceIntegrity);

 public:
  // Check the integrity of a given |buffer|'s content against the metadata in
  // the `IntegrityMetadataSet` provided.
  //
  // Either a `Resource` or `FetchResponseType` will be used to validate the
  // response's eligibility for client-initiated integrity checks. Ineligible
  // resources will fail the check.
  //
  // Note: If a resource's body is empty, then these methods are called with a
  // null `buffer`.
  static bool CheckSubresourceIntegrity(
      const IntegrityMetadataSet&,
      const SegmentedBuffer* buffer,
      const KURL& resource_url,
      const Resource&,
      const FeatureContext*,
      IntegrityReport&,
      HashMap<HashAlgorithm, String>* computed_hashes);
  static bool CheckSubresourceIntegrity(const IntegrityMetadataSet&,
                                        const SegmentedBuffer* buffer,
                                        const KURL& resource_url,
                                        const FetchResponseType,
                                        const String& raw_headers,
                                        const FeatureContext*,
                                        IntegrityReport&);
  static String GetSubresourceIntegrityHash(const SegmentedBuffer*,
                                            HashAlgorithm);

  static bool CheckUnencodedDigests(const Vector<IntegrityMetadata>& digests,
                                    const SegmentedBuffer* data);

  static HashAlgorithm IntegrityAlgorithmToHashAlgorithm(IntegrityAlgorithm);

  // The IntegrityMetadataSet argument is an out parameters which contains the
  // set of all valid, parsed metadata from |attribute|.
  static void ParseIntegrityAttribute(const String& attribute,
                                      IntegrityMetadataSet&,
                                      const FeatureContext*);
  static void ParseIntegrityAttribute(const String& attribute,
                                      IntegrityMetadataSet&,
                                      const FeatureContext*,
                                      IntegrityReport*);

  // Returns true if the element's `integrity` and `signature` attributes
  // produce a verifiable signature for the element's content.
  //
  // https://mikewest.github.io/inline-integrity/
  static bool VerifyInlineIntegrity(const String& integrity,
                                    const String& signatures,
                                    const String& source_code,
                                    const FeatureContext*);

 private:
  friend class SubresourceIntegrityTest;
  FRIEND_TEST_ALL_PREFIXES(SubresourceIntegrityTest, Parsing);
  FRIEND_TEST_ALL_PREFIXES(SubresourceIntegrityTest, ParseAlgorithm);
  FRIEND_TEST_ALL_PREFIXES(SubresourceIntegrityTest, ParseSignatureAlgorithm);
  FRIEND_TEST_ALL_PREFIXES(SubresourceIntegrityTest,
                           AlgorithmEnumPrioritization);
  FRIEND_TEST_ALL_PREFIXES(SubresourceIntegrityTest, FindBestAlgorithm);
  FRIEND_TEST_ALL_PREFIXES(SubresourceIntegritySignatureTest,
                           ParseSignatureAlgorithm);

  // The core implementation for all CheckSubresourceIntegrity functions.
  static bool CheckSubresourceIntegrityImpl(
      const IntegrityMetadataSet&,
      const SegmentedBuffer* buffer,
      const KURL& resource_url,
      const String& raw_headers,
      const FeatureContext*,
      IntegrityReport&,
      HashMap<HashAlgorithm, String>* computed_hashes);

  // Handles hash validation during SRI checks.
  static bool CheckHashesImpl(const Vector<IntegrityMetadata>&,
                              const SegmentedBuffer*,
                              const KURL&,
                              const FeatureContext*,
                              IntegrityReport&,
                              HashMap<HashAlgorithm, String>* computed_hashes);

  // Handles signature-based matching during SRI checks
  static bool CheckSignaturesImpl(const Vector<IntegrityMetadata>&,
                                  const KURL& resource_url,
                                  const String& raw_headers,
                                  IntegrityReport&);

  enum AlgorithmParseError { kAlgorithmUnparsable, kAlgorithmUnknown };
  using AlgorithmParseResult = base::expected<size_t, AlgorithmParseError>;

  static IntegrityAlgorithm FindBestAlgorithm(const Vector<IntegrityMetadata>&);

  static AlgorithmParseResult ParseAttributeAlgorithm(std::string_view token,
                                                      const FeatureContext*,
                                                      IntegrityAlgorithm&);
  typedef std::pair<const char*, IntegrityAlgorithm> AlgorithmPrefixPair;
  static bool ParseDigest(std::string_view maybe_digest, String& digest);
};

}  // namespace blink

#endif  // THIRD_PARTY_BLINK_RENDERER_PLATFORM_LOADER_SUBRESOURCE_INTEGRITY_H_