net/spdy/spdy_frame_reader.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_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
  12 namespace 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.
  28 class 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_