| Index: net/http2/hpack/huffman/http2_hpack_huffman_decoder.h
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| diff --git a/net/http2/hpack/huffman/http2_hpack_huffman_decoder.h b/net/http2/hpack/huffman/http2_hpack_huffman_decoder.h
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| deleted file mode 100644
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| index 7b8edd10c6372decd8252ea97a8dfa220c15e941..0000000000000000000000000000000000000000
|
| --- a/net/http2/hpack/huffman/http2_hpack_huffman_decoder.h
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| +++ /dev/null
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| @@ -1,149 +0,0 @@
|
| -// Copyright 2016 The Chromium Authors. All rights reserved.
|
| -// Use of this source code is governed by a BSD-style license that can be
|
| -// found in the LICENSE file.
|
| -
|
| -#ifndef NET_HTTP2_HPACK_HUFFMAN_HTTP2_HPACK_HUFFMAN_DECODER_H_
|
| -#define NET_HTTP2_HPACK_HUFFMAN_HTTP2_HPACK_HUFFMAN_DECODER_H_
|
| -
|
| -// HpackHuffmanDecoder is an incremental decoder of strings that have been
|
| -// encoded using the Huffman table defined in the HPACK spec.
|
| -// By incremental, we mean that the HpackHuffmanDecoder::Decode method does
|
| -// not require the entire string to be provided, and can instead decode the
|
| -// string as fragments of it become available (e.g. as HPACK block fragments
|
| -// are received for decoding by HpackEntryDecoder).
|
| -
|
| -#include <stddef.h>
|
| -
|
| -#include <iosfwd>
|
| -#include <string>
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| -
|
| -#include "base/strings/string_piece.h"
|
| -#include "net/base/net_export.h"
|
| -
|
| -namespace net {
|
| -
|
| -// HuffmanAccumulator is used to store bits during decoding, e.g. next N bits
|
| -// that have not yet been decoded, but have been extracted from the encoded
|
| -// string). An advantage of using a uint64 for the accumulator
|
| -// is that it has room for the bits of the longest code plus the bits of a full
|
| -// byte; that means that when adding more bits to the accumulator, it can always
|
| -// be done in whole bytes. For example, if we currently have 26 bits in the
|
| -// accumulator, and need more to decode the current symbol, we can add a whole
|
| -// byte to the accumulator, and not have to do juggling with adding 6 bits (to
|
| -// reach 30), and then keep track of the last two bits we've not been able to
|
| -// add to the accumulator.
|
| -typedef uint64_t HuffmanAccumulator;
|
| -typedef size_t HuffmanAccumulatorBitCount;
|
| -
|
| -// HuffmanBitBuffer stores the leading edge of bits to be decoded. The high
|
| -// order bit of accumulator_ is the next bit to be decoded.
|
| -class NET_EXPORT_PRIVATE HuffmanBitBuffer {
|
| - public:
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| - HuffmanBitBuffer();
|
| -
|
| - // Prepare for decoding a new Huffman encoded string.
|
| - void Reset();
|
| -
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| - // Add as many whole bytes to the accumulator (accumulator_) as possible,
|
| - // returning the number of bytes added.
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| - size_t AppendBytes(base::StringPiece input);
|
| -
|
| - // Get the bits of the accumulator.
|
| - HuffmanAccumulator value() const { return accumulator_; }
|
| -
|
| - // Number of bits of the encoded string that are in the accumulator
|
| - // (accumulator_).
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| - HuffmanAccumulatorBitCount count() const { return count_; }
|
| -
|
| - // Are there no bits in the accumulator?
|
| - bool IsEmpty() const { return count_ == 0; }
|
| -
|
| - // Number of additional bits that can be added to the accumulator.
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| - HuffmanAccumulatorBitCount free_count() const;
|
| -
|
| - // Consume the leading |code_length| bits of the accumulator.
|
| - void ConsumeBits(HuffmanAccumulatorBitCount code_length);
|
| -
|
| - // Are the contents valid for the end of a Huffman encoded string? The RFC
|
| - // states that EOS (end-of-string) symbol must not be explicitly encoded in
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| - // the bit stream, but any unused bits in the final byte must be set to the
|
| - // prefix of the EOS symbol, which is all 1 bits. So there can be at most 7
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| - // such bits.
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| - // Returns true if the bit buffer is empty, or contains at most 7 bits, all
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| - // of them 1. Otherwise returns false.
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| - bool InputProperlyTerminated() const;
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| -
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| - std::string DebugString() const;
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| -
|
| - private:
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| - HuffmanAccumulator accumulator_;
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| - HuffmanAccumulatorBitCount count_;
|
| -};
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| -
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| -inline std::ostream& operator<<(std::ostream& out, const HuffmanBitBuffer& v) {
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| - return out << v.DebugString();
|
| -}
|
| -
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| -class NET_EXPORT_PRIVATE HpackHuffmanDecoder {
|
| - public:
|
| - HpackHuffmanDecoder();
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| - ~HpackHuffmanDecoder();
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| -
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| - // Prepare for decoding a new Huffman encoded string.
|
| - void Reset() { bit_buffer_.Reset(); }
|
| -
|
| - // Decode the portion of a HPACK Huffman encoded string that is in |input|,
|
| - // appending the decoded symbols into |*output|, stopping when more bits are
|
| - // needed to determine the next symbol, which/ means that the input has been
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| - // drained, and also that the bit_buffer_ is empty or that the bits that are
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| - // in it are not a whole symbol.
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| - // If |input| is the start of a string, the caller must first call Reset.
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| - // If |input| includes the end of the encoded string, the caller must call
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| - // InputProperlyTerminated after Decode has returned true in order to
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| - // determine if the encoded string was properly terminated.
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| - // Returns false if something went wrong (e.g. the encoding contains the code
|
| - // EOS symbol). Otherwise returns true, in which case input has been fully
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| - // decoded or buffered; in particular, if the low-order bit of the final byte
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| - // of the input is not the last bit of an encoded symbol, then bit_buffer_
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| - // will contain the leading bits of the code for that symbol, but not the
|
| - // final bits of that code.
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| - // Note that output should be empty, but that it is not cleared by Decode().
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| - bool Decode(base::StringPiece input, std::string* output);
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| -
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| - // Is what remains in the bit_buffer_ valid at the end of an encoded string?
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| - // Call after passing the the final portion of a Huffman string to Decode,
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| - // and getting true as the result.
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| - bool InputProperlyTerminated() const {
|
| - return bit_buffer_.InputProperlyTerminated();
|
| - }
|
| -
|
| - bool IsEmptyForTest() const { return bit_buffer_.IsEmpty(); }
|
| -
|
| - std::string DebugString() const;
|
| -
|
| - //////////////////////////////////////////////////////////////////////////////
|
| - // Alternate implementations of Decode:
|
| -
|
| - // As above, implemented using a tree of if statements to determine the code
|
| - // length, etc., which are returned as a tree. See PrefixToInfo. This is the
|
| - // original implementation, current as of 2016-8-8.
|
| - bool DecodeWithIfTreeAndStruct(base::StringPiece input, std::string* output);
|
| -
|
| - // Based on DecodeWithIfTreeAndStruct, but adds an optimization for the common
|
| - // case of short codes (5, 6 or 7), which make up a large fraction of the
|
| - // frequency distribution on which the HPACK table was based.
|
| - // TODO(jamessynge): Be precise about that fraction.
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| - bool DecodeShortCodesFirst(base::StringPiece input, std::string* output);
|
| -
|
| - private:
|
| - HuffmanBitBuffer bit_buffer_;
|
| -};
|
| -
|
| -inline std::ostream& operator<<(std::ostream& out,
|
| - const HpackHuffmanDecoder& v) {
|
| - return out << v.DebugString();
|
| -}
|
| -
|
| -} // namespace net
|
| -
|
| -#endif // NET_HTTP2_HPACK_HUFFMAN_HTTP2_HPACK_HUFFMAN_DECODER_H_
|
|
|