| // Copyright 2018 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 QUICHE_QUIC_CORE_QPACK_QPACK_INSTRUCTION_ENCODER_H_ |
| #define QUICHE_QUIC_CORE_QPACK_QPACK_INSTRUCTION_ENCODER_H_ |
| |
| #include <cstdint> |
| #include <string> |
| |
| #include "absl/strings/string_view.h" |
| #include "quiche/quic/core/qpack/qpack_instructions.h" |
| #include "quiche/quic/platform/api/quic_export.h" |
| |
| namespace quic { |
| |
| // Generic instruction encoder class. Takes a QpackLanguage that describes a |
| // language, that is, a set of instruction opcodes together with a list of |
| // fields that follow each instruction. |
| class QUIC_EXPORT_PRIVATE QpackInstructionEncoder { |
| public: |
| QpackInstructionEncoder(); |
| QpackInstructionEncoder(const QpackInstructionEncoder&) = delete; |
| QpackInstructionEncoder& operator=(const QpackInstructionEncoder&) = delete; |
| |
| // Append encoded instruction to |output|. |
| void Encode(const QpackInstructionWithValues& instruction_with_values, |
| std::string* output); |
| |
| private: |
| enum class State { |
| // Write instruction opcode to |byte_|. |
| kOpcode, |
| // Select state based on type of current field. |
| kStartField, |
| // Write static bit to |byte_|. |
| kSbit, |
| // Encode an integer (|varint_| or |varint2_| or string length) with a |
| // prefix, using |byte_| for the high bits. |
| kVarintEncode, |
| // Determine if Huffman encoding should be used for the header name or |
| // value, set |use_huffman_| and |string_length_| appropriately, write the |
| // Huffman bit to |byte_|. |
| kStartString, |
| // Write header name or value, performing Huffman encoding if |use_huffman_| |
| // is true. |
| kWriteString |
| }; |
| |
| // One method for each state. Some append encoded bytes to |output|. |
| // Some only change internal state. |
| void DoOpcode(); |
| void DoStartField(); |
| void DoSBit(bool s_bit); |
| void DoVarintEncode(uint64_t varint, uint64_t varint2, std::string* output); |
| void DoStartString(absl::string_view name, absl::string_view value); |
| void DoWriteString(absl::string_view name, absl::string_view value, |
| std::string* output); |
| |
| // True if name or value should be Huffman encoded. |
| bool use_huffman_; |
| |
| // Length of name or value string to be written. |
| // If |use_huffman_| is true, length is after Huffman encoding. |
| size_t string_length_; |
| |
| // Storage for a single byte that contains multiple fields, that is, multiple |
| // states are writing it. |
| uint8_t byte_; |
| |
| // Encoding state. |
| State state_; |
| |
| // Instruction currently being decoded. |
| const QpackInstruction* instruction_; |
| |
| // Field currently being decoded. |
| QpackInstructionFields::const_iterator field_; |
| }; |
| |
| } // namespace quic |
| |
| #endif // QUICHE_QUIC_CORE_QPACK_QPACK_INSTRUCTION_ENCODER_H_ |