| // Copyright (c) 2020 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_COMMON_QUICHE_DATA_WRITER_H_ |
| #define QUICHE_COMMON_QUICHE_DATA_WRITER_H_ |
| |
| #include <cstddef> |
| #include <cstdint> |
| #include <cstring> |
| #include <limits> |
| |
| #include "absl/strings/string_view.h" |
| #include "quiche/common/platform/api/quiche_export.h" |
| #include "quiche/common/platform/api/quiche_logging.h" |
| #include "quiche/common/quiche_endian.h" |
| |
| namespace quiche { |
| |
| // Maximum value that can be properly encoded using RFC 9000 62-bit Variable |
| // Length Integer encoding. |
| enum : uint64_t { |
| kVarInt62MaxValue = UINT64_C(0x3fffffffffffffff), |
| }; |
| |
| // RFC 9000 62-bit Variable Length Integer encoding masks |
| // If a uint64_t anded with a mask is not 0 then the value is encoded |
| // using that length (or is too big, in the case of kVarInt62ErrorMask). |
| // Values must be checked in order (error, 8-, 4-, and then 2- bytes) |
| // and if none are non-0, the value is encoded in 1 byte. |
| enum : uint64_t { |
| kVarInt62ErrorMask = UINT64_C(0xc000000000000000), |
| kVarInt62Mask8Bytes = UINT64_C(0x3fffffffc0000000), |
| kVarInt62Mask4Bytes = UINT64_C(0x000000003fffc000), |
| kVarInt62Mask2Bytes = UINT64_C(0x0000000000003fc0), |
| }; |
| |
| // This class provides facilities for packing binary data. |
| // |
| // The QuicheDataWriter supports appending primitive values (int, string, etc) |
| // to a frame instance. The internal memory buffer is exposed as the "data" |
| // of the QuicheDataWriter. |
| class QUICHE_EXPORT QuicheDataWriter { |
| public: |
| // Creates a QuicheDataWriter where |buffer| is not owned |
| // using NETWORK_BYTE_ORDER endianness. |
| QuicheDataWriter(size_t size, char* buffer); |
| // Creates a QuicheDataWriter where |buffer| is not owned |
| // using the specified endianness. |
| QuicheDataWriter(size_t size, char* buffer, quiche::Endianness endianness); |
| QuicheDataWriter(const QuicheDataWriter&) = delete; |
| QuicheDataWriter& operator=(const QuicheDataWriter&) = delete; |
| |
| ~QuicheDataWriter(); |
| |
| // Returns the size of the QuicheDataWriter's data. |
| size_t length() const { return length_; } |
| |
| // Retrieves the buffer from the QuicheDataWriter without changing ownership. |
| char* data(); |
| |
| // Methods for adding to the payload. These values are appended to the end |
| // of the QuicheDataWriter payload. |
| |
| // Writes 8/16/32/64-bit unsigned integers. |
| bool WriteUInt8(uint8_t value); |
| bool WriteUInt16(uint16_t value); |
| bool WriteUInt32(uint32_t value); |
| bool WriteUInt64(uint64_t value); |
| |
| // Writes least significant |num_bytes| of a 64-bit unsigned integer in the |
| // correct byte order. |
| bool WriteBytesToUInt64(size_t num_bytes, uint64_t value); |
| |
| bool WriteStringPiece(absl::string_view val); |
| bool WriteStringPiece16(absl::string_view val); |
| bool WriteBytes(const void* data, size_t data_len); |
| bool WriteRepeatedByte(uint8_t byte, size_t count); |
| // Fills the remaining buffer with null characters. |
| void WritePadding(); |
| // Write padding of |count| bytes. |
| bool WritePaddingBytes(size_t count); |
| |
| // Write tag as a 32-bit unsigned integer to the payload. As tags are already |
| // converted to big endian (e.g., CHLO is 'C','H','L','O') in memory by TAG or |
| // MakeQuicTag and tags are written in byte order, so tags on the wire are |
| // in big endian. |
| bool WriteTag(uint32_t tag); |
| |
| // Write a 62-bit unsigned integer using RFC 9000 Variable Length Integer |
| // encoding. Returns false if the value is out of range or if there is no room |
| // in the buffer. |
| bool WriteVarInt62(uint64_t value); |
| |
| // Same as WriteVarInt62(uint64_t), but forces an encoding size to write to. |
| // This is not as optimized as WriteVarInt62(uint64_t). Returns false if the |
| // value does not fit in the specified write_length or if there is no room in |
| // the buffer. |
| bool WriteVarInt62WithForcedLength( |
| uint64_t value, QuicheVariableLengthIntegerLength write_length); |
| |
| // Writes a string piece as a consecutive length/content pair. The |
| // length uses RFC 9000 Variable Length Integer encoding. |
| bool WriteStringPieceVarInt62(const absl::string_view& string_piece); |
| |
| // Utility function to return the number of bytes needed to encode |
| // the given value using IETF VarInt62 encoding. Returns the number |
| // of bytes required to encode the given integer or 0 if the value |
| // is too large to encode. |
| static QuicheVariableLengthIntegerLength GetVarInt62Len(uint64_t value); |
| |
| // Advance the writer's position for writing by |length| bytes without writing |
| // anything. This method only makes sense to be used on a buffer that has |
| // already been written to (and is having certain parts rewritten). |
| bool Seek(size_t length); |
| |
| size_t capacity() const { return capacity_; } |
| |
| size_t remaining() const { return capacity_ - length_; } |
| |
| std::string DebugString() const; |
| |
| protected: |
| // Returns the location that the data should be written at, or nullptr if |
| // there is not enough room. Call EndWrite with the returned offset and the |
| // given length to pad out for the next write. |
| char* BeginWrite(size_t length); |
| |
| quiche::Endianness endianness() const { return endianness_; } |
| |
| char* buffer() const { return buffer_; } |
| |
| void IncreaseLength(size_t delta) { |
| QUICHE_DCHECK_LE(length_, std::numeric_limits<size_t>::max() - delta); |
| QUICHE_DCHECK_LE(length_, capacity_ - delta); |
| length_ += delta; |
| } |
| |
| private: |
| // TODO(fkastenholz, b/73004262) change buffer_, et al, to be uint8_t, not |
| // char. |
| char* buffer_; |
| size_t capacity_; // Allocation size of payload (or -1 if buffer is const). |
| size_t length_; // Current length of the buffer. |
| |
| // The endianness to write integers and floating numbers. |
| quiche::Endianness endianness_; |
| }; |
| |
| } // namespace quiche |
| |
| #endif // QUICHE_COMMON_QUICHE_DATA_WRITER_H_ |