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_SPDY_SPDY_FRAME_READER_H_
6#define NET_SPDY_SPDY_FRAME_READER_H_
7
8#include "base/basictypes.h"
9#include "base/strings/string_piece.h"
10#include "net/base/net_export.h"
11
12namespace net {
13
14// Used for reading SPDY frames. Though there isn't really anything terribly
15// SPDY-specific here, it's a helper class that's useful when doing SPDY
16// framing.
17//
18// To use, simply construct a SpdyFramerReader using the underlying buffer that
19// you'd like to read fields from, then call one of the Read*() methods to
20// actually do some reading.
21//
22// This class keeps an internal iterator to keep track of what's already been
23// read and each successive Read*() call automatically increments said iterator
24// on success. On failure, internal state of the SpdyFrameReader should not be
25// trusted and it is up to the caller to throw away the failed instance and
26// handle the error as appropriate. None of the Read*() methods should ever be
27// called after failure, as they will also fail immediately.
28class NET_EXPORT_PRIVATE SpdyFrameReader {
29 public:
30  // Caller must provide an underlying buffer to work on.
31  SpdyFrameReader(const char* data, const size_t len);
32
33  // Empty destructor.
34  ~SpdyFrameReader() {}
35
36  // Reads an 8-bit unsigned integer into the given output parameter.
37  // Forwards the internal iterator on success.
38  // Returns true on success, false otherwise.
39  bool ReadUInt8(uint8* result);
40
41  // Reads a 16-bit unsigned integer into the given output parameter.
42  // Forwards the internal iterator on success.
43  // Returns true on success, false otherwise.
44  bool ReadUInt16(uint16* result);
45
46  // Reads a 32-bit unsigned integer into the given output parameter.
47  // Forwards the internal iterator on success.
48  // Returns true on success, false otherwise.
49  bool ReadUInt32(uint32* result);
50
51  // Reads a 64-bit unsigned integer into the given output parameter.
52  // Forwards the internal iterator on success.
53  // Returns true on success, false otherwise.
54  bool ReadUInt64(uint64* result);
55
56  // Reads a 31-bit unsigned integer into the given output parameter. This is
57  // equivalent to ReadUInt32() above except that the highest-order bit is
58  // discarded.
59  // Forwards the internal iterator (by 4B) on success.
60  // Returns true on success, false otherwise.
61  bool ReadUInt31(uint32* result);
62
63  // Reads a 24-bit unsigned integer into the given output parameter.
64  // Forwards the internal iterator (by 3B) on success.
65  // Returns true on success, false otherwise.
66  bool ReadUInt24(uint32* result);
67
68  // Reads a string prefixed with 16-bit length into the given output parameter.
69  //
70  // NOTE: Does not copy but rather references strings in the underlying buffer.
71  // This should be kept in mind when handling memory management!
72  //
73  // Forwards the internal iterator on success.
74  // Returns true on success, false otherwise.
75  bool ReadStringPiece16(base::StringPiece* result);
76
77  // Reads a string prefixed with 32-bit length into the given output parameter.
78  //
79  // NOTE: Does not copy but rather references strings in the underlying buffer.
80  // This should be kept in mind when handling memory management!
81  //
82  // Forwards the internal iterator on success.
83  // Returns true on success, false otherwise.
84  bool ReadStringPiece32(base::StringPiece* result);
85
86  // Reads a given number of bytes into the given buffer. The buffer
87  // must be of adequate size.
88  // Forwards the internal iterator on success.
89  // Returns true on success, false otherwise.
90  bool ReadBytes(void* result, size_t size);
91
92  // Seeks a given number of bytes into the buffer from the current offset.
93  // Equivelant to an empty read.
94  // Forwards the internal iterator.
95  // Returns true on success, false otherwise.
96  bool Seek(size_t size);
97
98  // Rewinds this reader to the beginning of the frame.
99  void Rewind() { ofs_ = 0; }
100
101  // Returns true if the entirety of the underlying buffer has been read via
102  // Read*() calls.
103  bool IsDoneReading() const;
104
105  // Returns the number of bytes that have been consumed by the reader so far.
106  size_t GetBytesConsumed() const { return ofs_; }
107
108 private:
109  // Returns true if the underlying buffer has enough room to read the given
110  // amount of bytes.
111  bool CanRead(size_t bytes) const;
112
113  // To be called when a read fails for any reason.
114  void OnFailure();
115
116  // The data buffer that we're reading from.
117  const char* data_;
118
119  // The length of the data buffer that we're reading from.
120  const size_t len_;
121
122  // The location of the next read from our data buffer.
123  size_t ofs_;
124};
125
126}  // namespace net
127
128#endif  // NET_SPDY_SPDY_FRAME_READER_H_
129