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 18 namespace 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. 26 class 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. length()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 capacity()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