1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_QUIC_QUIC_DATA_WRITER_H_
6#define NET_QUIC_QUIC_DATA_WRITER_H_
7
8#include <string>
9
10#include "base/basictypes.h"
11#include "base/logging.h"
12#include "base/port.h"
13#include "base/strings/string_piece.h"
14#include "net/base/int128.h"
15#include "net/base/net_export.h"
16#include "net/quic/quic_protocol.h"
17
18namespace net {
19
20// This class provides facilities for packing QUIC data.
21//
22// The QuicDataWriter supports appending primitive values (int, string, etc)
23// to a frame instance.  The QuicDataWriter grows its internal memory buffer
24// dynamically to hold the sequence of primitive values.   The internal memory
25// buffer is exposed as the "data" of the QuicDataWriter.
26class NET_EXPORT_PRIVATE QuicDataWriter {
27 public:
28  explicit QuicDataWriter(size_t length);
29
30  ~QuicDataWriter();
31
32  // Returns the size of the QuicDataWriter's data.
33  size_t length() const { return length_; }
34
35  // Takes the buffer from the QuicDataWriter.
36  char* take();
37
38  // Methods for adding to the payload.  These values are appended to the end
39  // of the QuicDataWriter payload. Note - binary integers are written in
40  // host byte order (little endian) not network byte order (big endian).
41  bool WriteUInt8(uint8 value);
42  bool WriteUInt16(uint16 value);
43  bool WriteUInt32(uint32 value);
44  bool WriteUInt48(uint64 value);
45  bool WriteUInt64(uint64 value);
46  // Write unsigned floating point corresponding to the value. Large values are
47  // clamped to the maximum representable (kUFloat16MaxValue). Values that can
48  // not be represented directly are rounded down.
49  bool WriteUFloat16(uint64 value);
50  bool WriteStringPiece16(base::StringPiece val);
51  bool WriteIOVector(const IOVector& data);
52  bool WriteBytes(const void* data, size_t data_len);
53  bool WriteRepeatedByte(uint8 byte, size_t count);
54  // Fills the remaining buffer with null characters.
55  void WritePadding();
56
57  // Methods for editing the payload at a specific offset, where the
58  // offset must be within the writer's capacity.
59  // Return true if there is enough space at that offset, false otherwise.
60  bool WriteUInt8ToOffset(uint8 value, size_t offset);
61  bool WriteUInt32ToOffset(uint32 value, size_t offset);
62  bool WriteUInt48ToOffset(uint64 value, size_t offset);
63
64  size_t capacity() const {
65    return capacity_;
66  }
67
68 private:
69  // Returns the location that the data should be written at, or NULL if there
70  // is not enough room. Call EndWrite with the returned offset and the given
71  // length to pad out for the next write.
72  char* BeginWrite(size_t length);
73
74  char* buffer_;
75  size_t capacity_;  // Allocation size of payload (or -1 if buffer is const).
76  size_t length_;    // Current length of the buffer.
77
78  DISALLOW_COPY_AND_ASSIGN(QuicDataWriter);
79};
80
81}  // namespace net
82
83#endif  // NET_QUIC_QUIC_DATA_WRITER_H_
84