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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.
#ifndef QUICHE_QUIC_CORE_QUIC_DATA_WRITER_H_
#define QUICHE_QUIC_CORE_QUIC_DATA_WRITER_H_
#include <cstddef>
#include <cstdint>
#include "absl/strings/string_view.h"
#include "quic/core/quic_types.h"
#include "quic/platform/api/quic_export.h"
#include "common/quiche_data_writer.h"
#include "common/quiche_endian.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 : public quiche::QuicheDataWriter {
public:
// 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, quiche::Endianness endianness);
QuicDataWriter(const QuicDataWriter&) = delete;
QuicDataWriter& operator=(const QuicDataWriter&) = delete;
~QuicDataWriter();
// Methods for adding to the payload. These values are appended to the end
// of the QuicDataWriter payload.
// 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 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 QuicVariableLengthIntegerLength GetVarInt62Len(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);
// Write connection ID to the payload.
bool WriteConnectionId(QuicConnectionId connection_id);
// Write 8-bit length followed by connection ID to the payload.
bool WriteLengthPrefixedConnectionId(QuicConnectionId connection_id);
// Write |length| random bytes generated by |random|.
bool WriteRandomBytes(QuicRandom* random, size_t length);
// Write |length| random bytes generated by |random|. This MUST NOT be used
// for any application that requires cryptographically-secure randomness.
bool WriteInsecureRandomBytes(QuicRandom* random, size_t length);
};
} // namespace quic
#endif // QUICHE_QUIC_CORE_QUIC_DATA_WRITER_H_
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