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// Copyright (c) 2012 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 <cstddef>
#include <cstdint>
#include "net/third_party/quiche/src/quic/core/quic_types.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_endian.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_string_piece.h"
namespace quic {
class QuicRandom;
// Maximum value that can be properly encoded using VarInt62 coding.
const uint64_t kVarInt62MaxValue = UINT64_C(0x3fffffffffffffff);
// VarInt62 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.
const uint64_t kVarInt62ErrorMask = UINT64_C(0xc000000000000000);
const uint64_t kVarInt62Mask8Bytes = UINT64_C(0x3fffffffc0000000);
const uint64_t kVarInt62Mask4Bytes = UINT64_C(0x000000003fffc000);
const uint64_t kVarInt62Mask2Bytes = UINT64_C(0x0000000000003fc0);
// This class provides facilities for packing QUIC data.
// The QuicDataWriter supports appending primitive values (int, string, etc)
// to a frame instance. The internal memory buffer is exposed as the "data"
// of the QuicDataWriter.
class QUIC_EXPORT_PRIVATE QuicDataWriter {
// Creates a QuicDataWriter where |buffer| is not owned
// using NETWORK_BYTE_ORDER endianness.
QuicDataWriter(size_t size, char* buffer);
// Creates a QuicDataWriter where |buffer| is not owned
// using the specified endianness.
QuicDataWriter(size_t size, char* buffer, Endianness endianness);
QuicDataWriter(const QuicDataWriter&) = delete;
QuicDataWriter& operator=(const QuicDataWriter&) = delete;
// Returns the size of the QuicDataWriter's data.
size_t length() const { return length_; }
// Retrieves the buffer from the QuicDataWriter without changing ownership.
char* data();
// Methods for adding to the payload. These values are appended to the end
// of the QuicDataWriter 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);
// Write an unsigned-integer value per the IETF QUIC/Variable Length
// Integer encoding rules (see draft-ietf-quic-transport-08.txt).
// IETF Variable Length Integers have 62 significant bits, so the
// value to write must be in the range of 0...(2^62)-1. 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 WriteVarInt62(uint64_t value,
QuicVariableLengthIntegerLength write_length);
// Writes a string piece as a consecutive length/content pair. The
// length is VarInt62 encoded.
bool WriteStringPieceVarInt62(const QuicStringPiece& 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 QuicVariableLengthIntegerLength GetVarInt62Len(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);
// Write unsigned floating point corresponding to the value. Large values are
// clamped to the maximum representable (kUFloat16MaxValue). Values that can
// not be represented directly are rounded down.
bool WriteUFloat16(uint64_t value);
bool WriteStringPiece(QuicStringPiece val);
bool WriteStringPiece16(QuicStringPiece 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 connection ID to the payload.
bool WriteConnectionId(QuicConnectionId connection_id);
// 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 |length| random bytes generated by |random|.
bool WriteRandomBytes(QuicRandom* random, size_t length);
// 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;
// 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);
// 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.
Endianness endianness_;
} // namespace quic