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// Copyright 2024 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NET_SHARED_DICTIONARY_SHARED_DICTIONARY_HEADER_CHECKER_SOURCE_STREAM_H_
#define NET_SHARED_DICTIONARY_SHARED_DICTIONARY_HEADER_CHECKER_SOURCE_STREAM_H_
#include <memory>
#include <string>
#include "net/base/completion_once_callback.h"
#include "net/base/hash_value.h"
#include "net/base/net_errors.h"
#include "net/base/net_export.h"
#include "net/filter/source_stream.h"
namespace net {
class IOBuffer;
class GrowableIOBuffer;
// This class is used to check the header bytes of "Dictionary-Compressed
// Brotli" stream and "Dictionary-Compressed Zstandard" stream.
//
// The "Dictionary-Compressed Brotli" stream's header is 36 bytes containing:
// - 4 bytes magic number: 0xff, 0x44, 0x43, 0x42
// - 32 bytes SHA-256 hash digest of the dictionary.
// The "Dictionary-Compressed Zstandard" stream's header is 40 bytes containing:
// - 8 bytes magic number: 0x5e, 0x2a, 0x4d, 0x18, 0x20, 0x00, 0x00, 0x00
// - 32 bytes SHA-256 hash digest of the dictionary.
//
// When an error occurred while reading the upstream, this class passes the
// error to the reader of this class. When the header bytes from the upstream
// was different from the expected header, this class passes
// ERR_UNEXPECTED_CONTENT_DICTIONARY_HEADER to the reader.
//
// This class consumes the header bytes from the upstream. So the reader of
// this class can read the bytes after the header bytes.
class NET_EXPORT SharedDictionaryHeaderCheckerSourceStream
: public SourceStream {
public:
enum class Type {
kDictionaryCompressedBrotli,
kDictionaryCompressedZstd,
};
SharedDictionaryHeaderCheckerSourceStream(
std::unique_ptr<SourceStream> upstream,
Type type,
const SHA256HashValue& dictionary_hash);
SharedDictionaryHeaderCheckerSourceStream(
const SharedDictionaryHeaderCheckerSourceStream&) = delete;
SharedDictionaryHeaderCheckerSourceStream& operator=(
const SharedDictionaryHeaderCheckerSourceStream&) = delete;
~SharedDictionaryHeaderCheckerSourceStream() override;
// SourceStream implementation:
int Read(IOBuffer* dest_buffer,
int buffer_size,
CompletionOnceCallback callback) override;
std::string Description() const override;
bool MayHaveMoreBytes() const override;
private:
void ReadHeader();
void OnReadCompleted(int result);
bool CheckHeaderBuffer() const;
void HeaderCheckCompleted(int header_check_result);
base::span<const unsigned char> GetSignatureInBuffer() const;
base::span<const unsigned char> GetHashInBuffer() const;
std::unique_ptr<SourceStream> upstream_;
const Type type_;
const SHA256HashValue dictionary_hash_;
scoped_refptr<GrowableIOBuffer> head_read_buffer_;
int header_check_result_ = ERR_IO_PENDING;
scoped_refptr<IOBuffer> pending_read_buf_;
int pending_read_buf_len_ = 0;
CompletionOnceCallback pending_callback_;
};
} // namespace net
#endif // NET_SHARED_DICTIONARY_SHARED_DICTIONARY_HEADER_CHECKER_SOURCE_STREAM_H_
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