net/quic/quic_data_writer.h

   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 <cstddef>
   9 #include <string>
  10
  11 #include "base/basictypes.h"
  12 #include "base/logging.h"
  13 #include "base/port.h"
  14 #include "base/strings/string_piece.h"
  15 #include "net/base/int128.h"
  16 #include "net/base/net_export.h"
  17 #include "net/quic/quic_protocol.h"
  18
  19 namespace net {
  20
  21 // This class provides facilities for packing QUIC data.
  22 //
  23 // The QuicDataWriter supports appending primitive values (int, string, etc)
  24 // to a frame instance.  The internal memory buffer is exposed as the "data"
  25 // of the QuicDataWriter.
  26 class NET_EXPORT_PRIVATE QuicDataWriter {
  27  public:
  28   // Creates a QuicDataWriter where |buffer| is not owned.
  29   QuicDataWriter(size_t size, char* buffer);
  30
  31   ~QuicDataWriter();
  32
  33   // Returns the size of the QuicDataWriter's data.
  34   size_t length() const { return length_; }
  35
  36   // Retrieves the buffer from the QuicDataWriter without changing ownership.
  37   char* data();
  38
  39   // Methods for adding to the payload.  These values are appended to the end
  40   // of the QuicDataWriter payload. Note - binary integers are written in
  41   // host byte order (little endian) not network byte order (big endian).
  42   bool WriteUInt8(uint8 value);
  43   bool WriteUInt16(uint16 value);
  44   bool WriteUInt32(uint32 value);
  45   bool WriteUInt48(uint64 value);
  46   bool WriteUInt64(uint64 value);
  47   // Write unsigned floating point corresponding to the value. Large values are
  48   // clamped to the maximum representable (kUFloat16MaxValue). Values that can
  49   // not be represented directly are rounded down.
  50   bool WriteUFloat16(uint64 value);
  51   bool WriteStringPiece16(base::StringPiece val);
  52   bool WriteIOVector(const IOVector& data);
  53   bool WriteBytes(const void* data, size_t data_len);
  54   bool WriteRepeatedByte(uint8 byte, size_t count);
  55   // Fills the remaining buffer with null characters.
  56   void WritePadding();
  57
  58   size_t capacity() const {
  59     return capacity_;
  60   }
  61
  62  private:
  63   // Returns the location that the data should be written at, or nullptr if
  64   // there is not enough room. Call EndWrite with the returned offset and the
  65   // given length to pad out for the next write.
  66   char* BeginWrite(size_t length);
  67
  68   char* buffer_;
  69   size_t capacity_;  // Allocation size of payload (or -1 if buffer is const).
  70   size_t length_;    // Current length of the buffer.
  71
  72   DISALLOW_COPY_AND_ASSIGN(QuicDataWriter);
  73 };
  74
  75 }  // namespace net
  76
  77 #endif  // NET_QUIC_QUIC_DATA_WRITER_H_