Project import generated by Copybara.
PiperOrigin-RevId: 224614037
Change-Id: I14e53449d4aeccb328f86828c76b5f09dea0d4b8
diff --git a/http2/hpack/huffman/hpack_huffman_decoder.cc b/http2/hpack/huffman/hpack_huffman_decoder.cc
new file mode 100644
index 0000000..d1076ed
--- /dev/null
+++ b/http2/hpack/huffman/hpack_huffman_decoder.cc
@@ -0,0 +1,487 @@
+// 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.
+
+#include "net/third_party/quiche/src/http2/hpack/huffman/hpack_huffman_decoder.h"
+
+#include <bitset>
+#include <limits>
+
+#include "base/logging.h"
+
+// Terminology:
+//
+// Symbol - a plain text (unencoded) character (uint8), or the End-of-String
+// (EOS) symbol, 256.
+//
+// Code - the sequence of bits used to encode a symbol, varying in length from
+// 5 bits for the most common symbols (e.g. '0', '1', and 'a'), to
+// 30 bits for the least common (e.g. the EOS symbol).
+// For those symbols whose codes have the same length, their code values
+// are sorted such that the lower symbol value has a lower code value.
+//
+// Canonical - a symbol's cardinal value when sorted first by code length, and
+// then by symbol value. For example, canonical 0 is for ASCII '0'
+// (uint8 value 0x30), which is the first of the symbols whose code
+// is 5 bits long, and the last canonical is EOS, which is the last
+// of the symbols whose code is 30 bits long.
+
+// TODO(jamessynge): Remove use of binary literals, that is a C++ 14 feature.
+
+namespace http2 {
+namespace {
+
+// HuffmanCode is used to store the codes associated with symbols (a pattern of
+// from 5 to 30 bits).
+typedef uint32_t HuffmanCode;
+
+// HuffmanCodeBitCount is used to store a count of bits in a code.
+typedef uint16_t HuffmanCodeBitCount;
+
+// HuffmanCodeBitSet is used for producing a string version of a code because
+// std::bitset logs nicely.
+typedef std::bitset<32> HuffmanCodeBitSet;
+typedef std::bitset<64> HuffmanAccumulatorBitSet;
+
+static constexpr HuffmanCodeBitCount kMinCodeBitCount = 5;
+static constexpr HuffmanCodeBitCount kMaxCodeBitCount = 30;
+static constexpr HuffmanCodeBitCount kHuffmanCodeBitCount =
+ std::numeric_limits<HuffmanCode>::digits;
+
+static_assert(std::numeric_limits<HuffmanCode>::digits >= kMaxCodeBitCount,
+ "HuffmanCode isn't big enough.");
+
+static_assert(std::numeric_limits<HuffmanAccumulator>::digits >=
+ kMaxCodeBitCount,
+ "HuffmanAccumulator isn't big enough.");
+
+static constexpr HuffmanAccumulatorBitCount kHuffmanAccumulatorBitCount =
+ std::numeric_limits<HuffmanAccumulator>::digits;
+static constexpr HuffmanAccumulatorBitCount kExtraAccumulatorBitCount =
+ kHuffmanAccumulatorBitCount - kHuffmanCodeBitCount;
+
+// PrefixInfo holds info about a group of codes that are all of the same length.
+struct PrefixInfo {
+ // Given the leading bits (32 in this case) of the encoded string, and that
+ // they start with a code of length |code_length|, return the corresponding
+ // canonical for that leading code.
+ uint32_t DecodeToCanonical(HuffmanCode bits) const {
+ // What is the position of the canonical symbol being decoded within
+ // the canonical symbols of |length|?
+ HuffmanCode ordinal_in_length =
+ ((bits - first_code) >> (kHuffmanCodeBitCount - code_length));
+
+ // Combined with |canonical| to produce the position of the canonical symbol
+ // being decoded within all of the canonical symbols.
+ return first_canonical + ordinal_in_length;
+ }
+
+ const HuffmanCode first_code; // First code of this length, left justified in
+ // the field (i.e. the first bit of the code is
+ // the high-order bit).
+ const uint16_t code_length; // Length of the prefix code |base|.
+ const uint16_t first_canonical; // First canonical symbol of this length.
+};
+
+inline std::ostream& operator<<(std::ostream& out, const PrefixInfo& v) {
+ return out << "{first_code: " << HuffmanCodeBitSet(v.first_code)
+ << ", code_length: " << v.code_length
+ << ", first_canonical: " << v.first_canonical << "}";
+}
+
+// Given |value|, a sequence of the leading bits remaining to be decoded,
+// figure out which group of canonicals (by code length) that value starts
+// with. This function was generated.
+PrefixInfo PrefixToInfo(HuffmanCode value) {
+ if (value < 0b10111000000000000000000000000000) {
+ if (value < 0b01010000000000000000000000000000) {
+ return {0b00000000000000000000000000000000, 5, 0};
+ } else {
+ return {0b01010000000000000000000000000000, 6, 10};
+ }
+ } else {
+ if (value < 0b11111110000000000000000000000000) {
+ if (value < 0b11111000000000000000000000000000) {
+ return {0b10111000000000000000000000000000, 7, 36};
+ } else {
+ return {0b11111000000000000000000000000000, 8, 68};
+ }
+ } else {
+ if (value < 0b11111111110000000000000000000000) {
+ if (value < 0b11111111101000000000000000000000) {
+ if (value < 0b11111111010000000000000000000000) {
+ return {0b11111110000000000000000000000000, 10, 74};
+ } else {
+ return {0b11111111010000000000000000000000, 11, 79};
+ }
+ } else {
+ return {0b11111111101000000000000000000000, 12, 82};
+ }
+ } else {
+ if (value < 0b11111111111111100000000000000000) {
+ if (value < 0b11111111111110000000000000000000) {
+ if (value < 0b11111111111100000000000000000000) {
+ return {0b11111111110000000000000000000000, 13, 84};
+ } else {
+ return {0b11111111111100000000000000000000, 14, 90};
+ }
+ } else {
+ return {0b11111111111110000000000000000000, 15, 92};
+ }
+ } else {
+ if (value < 0b11111111111111110100100000000000) {
+ if (value < 0b11111111111111101110000000000000) {
+ if (value < 0b11111111111111100110000000000000) {
+ return {0b11111111111111100000000000000000, 19, 95};
+ } else {
+ return {0b11111111111111100110000000000000, 20, 98};
+ }
+ } else {
+ return {0b11111111111111101110000000000000, 21, 106};
+ }
+ } else {
+ if (value < 0b11111111111111111110101000000000) {
+ if (value < 0b11111111111111111011000000000000) {
+ return {0b11111111111111110100100000000000, 22, 119};
+ } else {
+ return {0b11111111111111111011000000000000, 23, 145};
+ }
+ } else {
+ if (value < 0b11111111111111111111101111000000) {
+ if (value < 0b11111111111111111111100000000000) {
+ if (value < 0b11111111111111111111011000000000) {
+ return {0b11111111111111111110101000000000, 24, 174};
+ } else {
+ return {0b11111111111111111111011000000000, 25, 186};
+ }
+ } else {
+ return {0b11111111111111111111100000000000, 26, 190};
+ }
+ } else {
+ if (value < 0b11111111111111111111111111110000) {
+ if (value < 0b11111111111111111111111000100000) {
+ return {0b11111111111111111111101111000000, 27, 205};
+ } else {
+ return {0b11111111111111111111111000100000, 28, 224};
+ }
+ } else {
+ return {0b11111111111111111111111111110000, 30, 253};
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+ }
+}
+
+// Mapping from canonical symbol (0 to 255) to actual symbol.
+// clang-format off
+constexpr unsigned char kCanonicalToSymbol[] = {
+ '0', '1', '2', 'a', 'c', 'e', 'i', 'o',
+ 's', 't', 0x20, '%', '-', '.', '/', '3',
+ '4', '5', '6', '7', '8', '9', '=', 'A',
+ '_', 'b', 'd', 'f', 'g', 'h', 'l', 'm',
+ 'n', 'p', 'r', 'u', ':', 'B', 'C', 'D',
+ 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L',
+ 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T',
+ 'U', 'V', 'W', 'Y', 'j', 'k', 'q', 'v',
+ 'w', 'x', 'y', 'z', '&', '*', ',', ';',
+ 'X', 'Z', '!', '\"', '(', ')', '?', '\'',
+ '+', '|', '#', '>', 0x00, '$', '@', '[',
+ ']', '~', '^', '}', '<', '`', '{', '\\',
+ 0xc3, 0xd0, 0x80, 0x82, 0x83, 0xa2, 0xb8, 0xc2,
+ 0xe0, 0xe2, 0x99, 0xa1, 0xa7, 0xac, 0xb0, 0xb1,
+ 0xb3, 0xd1, 0xd8, 0xd9, 0xe3, 0xe5, 0xe6, 0x81,
+ 0x84, 0x85, 0x86, 0x88, 0x92, 0x9a, 0x9c, 0xa0,
+ 0xa3, 0xa4, 0xa9, 0xaa, 0xad, 0xb2, 0xb5, 0xb9,
+ 0xba, 0xbb, 0xbd, 0xbe, 0xc4, 0xc6, 0xe4, 0xe8,
+ 0xe9, 0x01, 0x87, 0x89, 0x8a, 0x8b, 0x8c, 0x8d,
+ 0x8f, 0x93, 0x95, 0x96, 0x97, 0x98, 0x9b, 0x9d,
+ 0x9e, 0xa5, 0xa6, 0xa8, 0xae, 0xaf, 0xb4, 0xb6,
+ 0xb7, 0xbc, 0xbf, 0xc5, 0xe7, 0xef, 0x09, 0x8e,
+ 0x90, 0x91, 0x94, 0x9f, 0xab, 0xce, 0xd7, 0xe1,
+ 0xec, 0xed, 0xc7, 0xcf, 0xea, 0xeb, 0xc0, 0xc1,
+ 0xc8, 0xc9, 0xca, 0xcd, 0xd2, 0xd5, 0xda, 0xdb,
+ 0xee, 0xf0, 0xf2, 0xf3, 0xff, 0xcb, 0xcc, 0xd3,
+ 0xd4, 0xd6, 0xdd, 0xde, 0xdf, 0xf1, 0xf4, 0xf5,
+ 0xf6, 0xf7, 0xf8, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe,
+ 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x0b,
+ 0x0c, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14,
+ 0x15, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d,
+ 0x1e, 0x1f, 0x7f, 0xdc, 0xf9, 0x0a, 0x0d, 0x16,
+};
+// clang-format on
+
+constexpr size_t kShortCodeTableSize = 124;
+struct ShortCodeInfo {
+ uint8_t symbol;
+ uint8_t length;
+} kShortCodeTable[kShortCodeTableSize] = {
+ {0x30, 5}, // Match: 0b0000000, Symbol: 0
+ {0x30, 5}, // Match: 0b0000001, Symbol: 0
+ {0x30, 5}, // Match: 0b0000010, Symbol: 0
+ {0x30, 5}, // Match: 0b0000011, Symbol: 0
+ {0x31, 5}, // Match: 0b0000100, Symbol: 1
+ {0x31, 5}, // Match: 0b0000101, Symbol: 1
+ {0x31, 5}, // Match: 0b0000110, Symbol: 1
+ {0x31, 5}, // Match: 0b0000111, Symbol: 1
+ {0x32, 5}, // Match: 0b0001000, Symbol: 2
+ {0x32, 5}, // Match: 0b0001001, Symbol: 2
+ {0x32, 5}, // Match: 0b0001010, Symbol: 2
+ {0x32, 5}, // Match: 0b0001011, Symbol: 2
+ {0x61, 5}, // Match: 0b0001100, Symbol: a
+ {0x61, 5}, // Match: 0b0001101, Symbol: a
+ {0x61, 5}, // Match: 0b0001110, Symbol: a
+ {0x61, 5}, // Match: 0b0001111, Symbol: a
+ {0x63, 5}, // Match: 0b0010000, Symbol: c
+ {0x63, 5}, // Match: 0b0010001, Symbol: c
+ {0x63, 5}, // Match: 0b0010010, Symbol: c
+ {0x63, 5}, // Match: 0b0010011, Symbol: c
+ {0x65, 5}, // Match: 0b0010100, Symbol: e
+ {0x65, 5}, // Match: 0b0010101, Symbol: e
+ {0x65, 5}, // Match: 0b0010110, Symbol: e
+ {0x65, 5}, // Match: 0b0010111, Symbol: e
+ {0x69, 5}, // Match: 0b0011000, Symbol: i
+ {0x69, 5}, // Match: 0b0011001, Symbol: i
+ {0x69, 5}, // Match: 0b0011010, Symbol: i
+ {0x69, 5}, // Match: 0b0011011, Symbol: i
+ {0x6f, 5}, // Match: 0b0011100, Symbol: o
+ {0x6f, 5}, // Match: 0b0011101, Symbol: o
+ {0x6f, 5}, // Match: 0b0011110, Symbol: o
+ {0x6f, 5}, // Match: 0b0011111, Symbol: o
+ {0x73, 5}, // Match: 0b0100000, Symbol: s
+ {0x73, 5}, // Match: 0b0100001, Symbol: s
+ {0x73, 5}, // Match: 0b0100010, Symbol: s
+ {0x73, 5}, // Match: 0b0100011, Symbol: s
+ {0x74, 5}, // Match: 0b0100100, Symbol: t
+ {0x74, 5}, // Match: 0b0100101, Symbol: t
+ {0x74, 5}, // Match: 0b0100110, Symbol: t
+ {0x74, 5}, // Match: 0b0100111, Symbol: t
+ {0x20, 6}, // Match: 0b0101000, Symbol: (space)
+ {0x20, 6}, // Match: 0b0101001, Symbol: (space)
+ {0x25, 6}, // Match: 0b0101010, Symbol: %
+ {0x25, 6}, // Match: 0b0101011, Symbol: %
+ {0x2d, 6}, // Match: 0b0101100, Symbol: -
+ {0x2d, 6}, // Match: 0b0101101, Symbol: -
+ {0x2e, 6}, // Match: 0b0101110, Symbol: .
+ {0x2e, 6}, // Match: 0b0101111, Symbol: .
+ {0x2f, 6}, // Match: 0b0110000, Symbol: /
+ {0x2f, 6}, // Match: 0b0110001, Symbol: /
+ {0x33, 6}, // Match: 0b0110010, Symbol: 3
+ {0x33, 6}, // Match: 0b0110011, Symbol: 3
+ {0x34, 6}, // Match: 0b0110100, Symbol: 4
+ {0x34, 6}, // Match: 0b0110101, Symbol: 4
+ {0x35, 6}, // Match: 0b0110110, Symbol: 5
+ {0x35, 6}, // Match: 0b0110111, Symbol: 5
+ {0x36, 6}, // Match: 0b0111000, Symbol: 6
+ {0x36, 6}, // Match: 0b0111001, Symbol: 6
+ {0x37, 6}, // Match: 0b0111010, Symbol: 7
+ {0x37, 6}, // Match: 0b0111011, Symbol: 7
+ {0x38, 6}, // Match: 0b0111100, Symbol: 8
+ {0x38, 6}, // Match: 0b0111101, Symbol: 8
+ {0x39, 6}, // Match: 0b0111110, Symbol: 9
+ {0x39, 6}, // Match: 0b0111111, Symbol: 9
+ {0x3d, 6}, // Match: 0b1000000, Symbol: =
+ {0x3d, 6}, // Match: 0b1000001, Symbol: =
+ {0x41, 6}, // Match: 0b1000010, Symbol: A
+ {0x41, 6}, // Match: 0b1000011, Symbol: A
+ {0x5f, 6}, // Match: 0b1000100, Symbol: _
+ {0x5f, 6}, // Match: 0b1000101, Symbol: _
+ {0x62, 6}, // Match: 0b1000110, Symbol: b
+ {0x62, 6}, // Match: 0b1000111, Symbol: b
+ {0x64, 6}, // Match: 0b1001000, Symbol: d
+ {0x64, 6}, // Match: 0b1001001, Symbol: d
+ {0x66, 6}, // Match: 0b1001010, Symbol: f
+ {0x66, 6}, // Match: 0b1001011, Symbol: f
+ {0x67, 6}, // Match: 0b1001100, Symbol: g
+ {0x67, 6}, // Match: 0b1001101, Symbol: g
+ {0x68, 6}, // Match: 0b1001110, Symbol: h
+ {0x68, 6}, // Match: 0b1001111, Symbol: h
+ {0x6c, 6}, // Match: 0b1010000, Symbol: l
+ {0x6c, 6}, // Match: 0b1010001, Symbol: l
+ {0x6d, 6}, // Match: 0b1010010, Symbol: m
+ {0x6d, 6}, // Match: 0b1010011, Symbol: m
+ {0x6e, 6}, // Match: 0b1010100, Symbol: n
+ {0x6e, 6}, // Match: 0b1010101, Symbol: n
+ {0x70, 6}, // Match: 0b1010110, Symbol: p
+ {0x70, 6}, // Match: 0b1010111, Symbol: p
+ {0x72, 6}, // Match: 0b1011000, Symbol: r
+ {0x72, 6}, // Match: 0b1011001, Symbol: r
+ {0x75, 6}, // Match: 0b1011010, Symbol: u
+ {0x75, 6}, // Match: 0b1011011, Symbol: u
+ {0x3a, 7}, // Match: 0b1011100, Symbol: :
+ {0x42, 7}, // Match: 0b1011101, Symbol: B
+ {0x43, 7}, // Match: 0b1011110, Symbol: C
+ {0x44, 7}, // Match: 0b1011111, Symbol: D
+ {0x45, 7}, // Match: 0b1100000, Symbol: E
+ {0x46, 7}, // Match: 0b1100001, Symbol: F
+ {0x47, 7}, // Match: 0b1100010, Symbol: G
+ {0x48, 7}, // Match: 0b1100011, Symbol: H
+ {0x49, 7}, // Match: 0b1100100, Symbol: I
+ {0x4a, 7}, // Match: 0b1100101, Symbol: J
+ {0x4b, 7}, // Match: 0b1100110, Symbol: K
+ {0x4c, 7}, // Match: 0b1100111, Symbol: L
+ {0x4d, 7}, // Match: 0b1101000, Symbol: M
+ {0x4e, 7}, // Match: 0b1101001, Symbol: N
+ {0x4f, 7}, // Match: 0b1101010, Symbol: O
+ {0x50, 7}, // Match: 0b1101011, Symbol: P
+ {0x51, 7}, // Match: 0b1101100, Symbol: Q
+ {0x52, 7}, // Match: 0b1101101, Symbol: R
+ {0x53, 7}, // Match: 0b1101110, Symbol: S
+ {0x54, 7}, // Match: 0b1101111, Symbol: T
+ {0x55, 7}, // Match: 0b1110000, Symbol: U
+ {0x56, 7}, // Match: 0b1110001, Symbol: V
+ {0x57, 7}, // Match: 0b1110010, Symbol: W
+ {0x59, 7}, // Match: 0b1110011, Symbol: Y
+ {0x6a, 7}, // Match: 0b1110100, Symbol: j
+ {0x6b, 7}, // Match: 0b1110101, Symbol: k
+ {0x71, 7}, // Match: 0b1110110, Symbol: q
+ {0x76, 7}, // Match: 0b1110111, Symbol: v
+ {0x77, 7}, // Match: 0b1111000, Symbol: w
+ {0x78, 7}, // Match: 0b1111001, Symbol: x
+ {0x79, 7}, // Match: 0b1111010, Symbol: y
+ {0x7a, 7}, // Match: 0b1111011, Symbol: z
+};
+
+} // namespace
+
+HuffmanBitBuffer::HuffmanBitBuffer() {
+ Reset();
+}
+
+void HuffmanBitBuffer::Reset() {
+ accumulator_ = 0;
+ count_ = 0;
+}
+
+size_t HuffmanBitBuffer::AppendBytes(Http2StringPiece input) {
+ HuffmanAccumulatorBitCount free_cnt = free_count();
+ size_t bytes_available = input.size();
+ if (free_cnt < 8 || bytes_available == 0) {
+ return 0;
+ }
+
+ // Top up |accumulator_| until there isn't room for a whole byte.
+ size_t bytes_used = 0;
+ auto* ptr = reinterpret_cast<const uint8_t*>(input.data());
+ do {
+ auto b = static_cast<HuffmanAccumulator>(*ptr++);
+ free_cnt -= 8;
+ accumulator_ |= (b << free_cnt);
+ ++bytes_used;
+ } while (free_cnt >= 8 && bytes_used < bytes_available);
+ count_ += (bytes_used * 8);
+ return bytes_used;
+}
+
+HuffmanAccumulatorBitCount HuffmanBitBuffer::free_count() const {
+ return kHuffmanAccumulatorBitCount - count_;
+}
+
+void HuffmanBitBuffer::ConsumeBits(HuffmanAccumulatorBitCount code_length) {
+ DCHECK_LE(code_length, count_);
+ accumulator_ <<= code_length;
+ count_ -= code_length;
+}
+
+bool HuffmanBitBuffer::InputProperlyTerminated() const {
+ auto cnt = count();
+ if (cnt < 8) {
+ if (cnt == 0) {
+ return true;
+ }
+ HuffmanAccumulator expected = ~(~HuffmanAccumulator() >> cnt);
+ // We expect all the bits below the high order |cnt| bits of accumulator_
+ // to be cleared as we perform left shift operations while decoding.
+ DCHECK_EQ(accumulator_ & ~expected, 0u)
+ << "\n expected: " << HuffmanAccumulatorBitSet(expected) << "\n "
+ << *this;
+ return accumulator_ == expected;
+ }
+ return false;
+}
+
+Http2String HuffmanBitBuffer::DebugString() const {
+ std::stringstream ss;
+ ss << "{accumulator: " << HuffmanAccumulatorBitSet(accumulator_)
+ << "; count: " << count_ << "}";
+ return ss.str();
+}
+
+HpackHuffmanDecoder::HpackHuffmanDecoder() = default;
+
+HpackHuffmanDecoder::~HpackHuffmanDecoder() = default;
+
+bool HpackHuffmanDecoder::Decode(Http2StringPiece input, Http2String* output) {
+ DVLOG(1) << "HpackHuffmanDecoder::Decode";
+
+ // Fill bit_buffer_ from input.
+ input.remove_prefix(bit_buffer_.AppendBytes(input));
+
+ while (true) {
+ DVLOG(3) << "Enter Decode Loop, bit_buffer_: " << bit_buffer_;
+ if (bit_buffer_.count() >= 7) {
+ // Get high 7 bits of the bit buffer, see if that contains a complete
+ // code of 5, 6 or 7 bits.
+ uint8_t short_code =
+ bit_buffer_.value() >> (kHuffmanAccumulatorBitCount - 7);
+ DCHECK_LT(short_code, 128);
+ if (short_code < kShortCodeTableSize) {
+ ShortCodeInfo info = kShortCodeTable[short_code];
+ bit_buffer_.ConsumeBits(info.length);
+ output->push_back(static_cast<char>(info.symbol));
+ continue;
+ }
+ // The code is more than 7 bits long. Use PrefixToInfo, etc. to decode
+ // longer codes.
+ } else {
+ // We may have (mostly) drained bit_buffer_. If we can top it up, try
+ // using the table decoder above.
+ size_t byte_count = bit_buffer_.AppendBytes(input);
+ if (byte_count > 0) {
+ input.remove_prefix(byte_count);
+ continue;
+ }
+ }
+
+ HuffmanCode code_prefix = bit_buffer_.value() >> kExtraAccumulatorBitCount;
+ DVLOG(3) << "code_prefix: " << HuffmanCodeBitSet(code_prefix);
+
+ PrefixInfo prefix_info = PrefixToInfo(code_prefix);
+ DVLOG(3) << "prefix_info: " << prefix_info;
+ DCHECK_LE(kMinCodeBitCount, prefix_info.code_length);
+ DCHECK_LE(prefix_info.code_length, kMaxCodeBitCount);
+
+ if (prefix_info.code_length <= bit_buffer_.count()) {
+ // We have enough bits for one code.
+ uint32_t canonical = prefix_info.DecodeToCanonical(code_prefix);
+ if (canonical < 256) {
+ // Valid code.
+ char c = kCanonicalToSymbol[canonical];
+ output->push_back(c);
+ bit_buffer_.ConsumeBits(prefix_info.code_length);
+ continue;
+ }
+ // Encoder is not supposed to explicity encode the EOS symbol.
+ DLOG(ERROR) << "EOS explicitly encoded!\n " << bit_buffer_ << "\n "
+ << prefix_info;
+ return false;
+ }
+ // bit_buffer_ doesn't have enough bits in it to decode the next symbol.
+ // Append to it as many bytes as are available AND fit.
+ size_t byte_count = bit_buffer_.AppendBytes(input);
+ if (byte_count == 0) {
+ DCHECK_EQ(input.size(), 0u);
+ return true;
+ }
+ input.remove_prefix(byte_count);
+ }
+}
+
+Http2String HpackHuffmanDecoder::DebugString() const {
+ return bit_buffer_.DebugString();
+}
+
+} // namespace http2
