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. ~SpdyFrameReader()34 ~SpdyFrameReader() {} 35 36 // Reads an 8-bit unsigned integer into the given output parameter. 37 // Forwards the internal iterater 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 iterater 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 iterater on success. 48 // Returns true on success, false otherwise. 49 bool ReadUInt32(uint32* result); 50 51 // Reads a 31-bit unsigned integer into the given output parameter. This is 52 // equivalent to ReadUInt32() above except that the highest-order bit is 53 // discarded. 54 // Forwards the internal iterater (by 4B) on success. 55 // Returns true on success, false otherwise. 56 bool ReadUInt31(uint32* result); 57 58 // Reads a 24-bit unsigned integer into the given output parameter. 59 // Forwards the internal iterater (by 3B) on success. 60 // Returns true on success, false otherwise. 61 bool ReadUInt24(uint32* result); 62 63 // Reads a string prefixed with 16-bit length into the given output parameter. 64 // 65 // NOTE: Does not copy but rather references strings in the underlying buffer. 66 // This should be kept in mind when handling memory management! 67 // 68 // Forwards the internal iterater on success. 69 // Returns true on success, false otherwise. 70 bool ReadStringPiece16(base::StringPiece* result); 71 72 // Reads a string prefixed with 32-bit length into the given output parameter. 73 // 74 // NOTE: Does not copy but rather references strings in the underlying buffer. 75 // This should be kept in mind when handling memory management! 76 // 77 // Forwards the internal iterater on success. 78 // Returns true on success, false otherwise. 79 bool ReadStringPiece32(base::StringPiece* result); 80 81 // Reads a given number of bytes into the given buffer. The buffer 82 // must be of adequate size. 83 // Forwards the internal iterater on success. 84 // Returns true on success, false otherwise. 85 bool ReadBytes(void* result, size_t size); 86 87 // Seeks a given number of bytes into the buffer from the current offset. 88 // Equivelant to an empty read. 89 // Forwards the internal iterator. 90 // Returns true on success, false otherwise. 91 bool Seek(size_t size); 92 93 // Rewinds this reader to the beginning of the frame. Rewind()94 void Rewind() { ofs_ = 0; } 95 96 // Returns true if the entirety of the underlying buffer has been read via 97 // Read*() calls. 98 bool IsDoneReading() const; 99 100 // Returns the number of bytes that have been consumed by the reader so far. GetBytesConsumed()101 size_t GetBytesConsumed() const { return ofs_; } 102 103 private: 104 // Returns true if the underlying buffer has enough room to read the given 105 // amount of bytes. 106 bool CanRead(size_t bytes) const; 107 108 // To be called when a read fails for any reason. 109 void OnFailure(); 110 111 // The data buffer that we're reading from. 112 const char* data_; 113 114 // The length of the data buffer that we're reading from. 115 const size_t len_; 116 117 // The location of the next read from our data buffer. 118 size_t ofs_; 119 }; 120 121 } // namespace net 122 123 #endif // NET_SPDY_SPDY_FRAME_READER_H_ 124