blob: d85f631ab1ba86940264c024bb3ba3cdd6466e6c [file] [log] [blame]
// 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.
#include <cstddef>
#include <cstdint>
#include <cstring>
#include <limits>
#include "absl/strings/string_view.h"
#include "common/platform/api/quiche_export.h"
#include "common/platform/api/quiche_logging.h"
#include "common/quiche_endian.h"
namespace quiche {
// 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_PRIVATE QuicheDataWriter {
// 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;
// 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);
// 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);
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;
// 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