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// Copyright (c) 2012 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef NET_SPDY_SPDY_FRAME_READER_H_
#define NET_SPDY_SPDY_FRAME_READER_H_
#include "base/basictypes.h"
#include "base/strings/string_piece.h"
#include "net/base/net_export.h"
namespace net {
// Used for reading SPDY frames. Though there isn't really anything terribly
// SPDY-specific here, it's a helper class that's useful when doing SPDY
// framing.
//
// To use, simply construct a SpdyFramerReader using the underlying buffer that
// you'd like to read fields from, then call one of the Read*() methods to
// actually do some reading.
//
// This class keeps an internal iterator to keep track of what's already been
// read and each successive Read*() call automatically increments said iterator
// on success. On failure, internal state of the SpdyFrameReader should not be
// trusted and it is up to the caller to throw away the failed instance and
// handle the error as appropriate. None of the Read*() methods should ever be
// called after failure, as they will also fail immediately.
class NET_EXPORT_PRIVATE SpdyFrameReader {
public:
// Caller must provide an underlying buffer to work on.
SpdyFrameReader(const char* data, const size_t len);
// Empty destructor.
~SpdyFrameReader() {}
// Reads an 8-bit unsigned integer into the given output parameter.
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadUInt8(uint8* result);
// Reads a 16-bit unsigned integer into the given output parameter.
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadUInt16(uint16* result);
// Reads a 32-bit unsigned integer into the given output parameter.
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadUInt32(uint32* result);
// Reads a 64-bit unsigned integer into the given output parameter.
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadUInt64(uint64* result);
// Reads a 31-bit unsigned integer into the given output parameter. This is
// equivalent to ReadUInt32() above except that the highest-order bit is
// discarded.
// Forwards the internal iterator (by 4B) on success.
// Returns true on success, false otherwise.
bool ReadUInt31(uint32* result);
// Reads a 24-bit unsigned integer into the given output parameter.
// Forwards the internal iterator (by 3B) on success.
// Returns true on success, false otherwise.
bool ReadUInt24(uint32* result);
// Reads a string prefixed with 16-bit length into the given output parameter.
//
// NOTE: Does not copy but rather references strings in the underlying buffer.
// This should be kept in mind when handling memory management!
//
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadStringPiece16(base::StringPiece* result);
// Reads a string prefixed with 32-bit length into the given output parameter.
//
// NOTE: Does not copy but rather references strings in the underlying buffer.
// This should be kept in mind when handling memory management!
//
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadStringPiece32(base::StringPiece* result);
// Reads a given number of bytes into the given buffer. The buffer
// must be of adequate size.
// Forwards the internal iterator on success.
// Returns true on success, false otherwise.
bool ReadBytes(void* result, size_t size);
// Seeks a given number of bytes into the buffer from the current offset.
// Equivelant to an empty read.
// Forwards the internal iterator.
// Returns true on success, false otherwise.
bool Seek(size_t size);
// Rewinds this reader to the beginning of the frame.
void Rewind() { ofs_ = 0; }
// Returns true if the entirety of the underlying buffer has been read via
// Read*() calls.
bool IsDoneReading() const;
// Returns the number of bytes that have been consumed by the reader so far.
size_t GetBytesConsumed() const { return ofs_; }
private:
// Returns true if the underlying buffer has enough room to read the given
// amount of bytes.
bool CanRead(size_t bytes) const;
// To be called when a read fails for any reason.
void OnFailure();
// The data buffer that we're reading from.
const char* data_;
// The length of the data buffer that we're reading from.
const size_t len_;
// The location of the next read from our data buffer.
size_t ofs_;
};
} // namespace net
#endif // NET_SPDY_SPDY_FRAME_READER_H_
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