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/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 a 16-bit unsigned integer into the given output parameter.
  37   // Forwards the internal iterater on success.
  38   // Returns true on success, false otherwise.
  39   bool ReadUInt16(uint16* result);
  40
  41   // Reads a 32-bit unsigned integer into the given output parameter.
  42   // Forwards the internal iterater on success.
  43   // Returns true on success, false otherwise.
  44   bool ReadUInt32(uint32* result);
  45
  46   // Reads a string prefixed with 16-bit length into the given output parameter.
  47   //
  48   // NOTE: Does not copy but rather references strings in the underlying buffer.
  49   // This should be kept in mind when handling memory management!
  50   //
  51   // Forwards the internal iterater on success.
  52   // Returns true on success, false otherwise.
  53   bool ReadStringPiece16(base::StringPiece* result);
  54
  55   // Reads a string prefixed with 32-bit length into the given output parameter.
  56   //
  57   // NOTE: Does not copy but rather references strings in the underlying buffer.
  58   // This should be kept in mind when handling memory management!
  59   //
  60   // Forwards the internal iterater on success.
  61   // Returns true on success, false otherwise.
  62   bool ReadStringPiece32(base::StringPiece* result);
  63
  64   // Reads a given number of bytes into the given buffer. The buffer
  65   // must be of adequate size.
  66   // Forwards the internal iterater on success.
  67   // Returns true on success, false otherwise.
  68   bool ReadBytes(void* result, size_t size);
  69
  70   // Returns true if the entirety of the underlying buffer has been read via
  71   // Read*() calls.
  72   bool IsDoneReading() const;
  73
  74   // Returns the number of bytes that have been consumed by the reader so far.
  75   size_t GetBytesConsumed() const { return ofs_; }
  76
  77  private:
  78   // Returns true if the underlying buffer has enough room to read the given
  79   // amount of bytes.
  80   bool CanRead(size_t bytes) const;
  81
  82   // To be called when a read fails for any reason.
  83   void OnFailure();
  84
  85   // The data buffer that we're reading from.
  86   const char* data_;
  87
  88   // The length of the data buffer that we're reading from.
  89   const size_t len_;
  90
  91   // The location of the next read from our data buffer.
  92   size_t ofs_;
  93 };
  94
  95 }  // namespace net
  96
  97 #endif  // NET_SPDY_SPDY_FRAME_READER_H_