net/spdy/hpack_input_stream.h

   1 // Copyright 2014 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_HPACK_INPUT_STREAM_H_
   6 #define NET_SPDY_HPACK_INPUT_STREAM_H_
   7
   8 #include <string>
   9
  10 #include "base/basictypes.h"
  11 #include "base/macros.h"
  12 #include "base/strings/string_piece.h"
  13 #include "net/base/net_export.h"
  14 #include "net/spdy/hpack_constants.h"
  15 #include "net/spdy/hpack_huffman_table.h"
  16
  17 // All section references below are to
  18 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08
  19
  20 namespace net {
  21
  22 // An HpackInputStream handles all the low-level details of decoding
  23 // header fields.
  24 class NET_EXPORT_PRIVATE HpackInputStream {
  25  public:
  26   // |max_string_literal_size| is the largest that any one string
  27   // literal (header name or header value) can be.
  28   HpackInputStream(uint32 max_string_literal_size, base::StringPiece buffer);
  29   ~HpackInputStream();
  30
  31   // Returns whether or not there is more data to process.
  32   bool HasMoreData() const;
  33
  34   // If the next bits of input match |prefix|, consumes them and returns true.
  35   // Otherwise, consumes nothing and returns false.
  36   bool MatchPrefixAndConsume(HpackPrefix prefix);
  37
  38   // The Decode* functions return true and fill in their arguments if
  39   // decoding was successful, or false if an error was encountered.
  40
  41   bool DecodeNextUint32(uint32* I);
  42   bool DecodeNextIdentityString(base::StringPiece* str);
  43   bool DecodeNextHuffmanString(const HpackHuffmanTable& table,
  44                                std::string* str);
  45
  46   // Stores input bits into the most-significant, unfilled bits of |out|.
  47   // |peeked_count| is the number of filled bits in |out| which have been
  48   // previously peeked. PeekBits() will fill some number of remaining bits,
  49   // returning the new total number via |peeked_count|. Returns true if one
  50   // or more additional bits could be peeked, and false otherwise.
  51   bool PeekBits(size_t* peeked_count, uint32* out);
  52
  53   // Consumes |count| bits of input. Generally paired with PeekBits().
  54   void ConsumeBits(size_t count);
  55
  56   // If not currently on a byte boundary, consumes and discards
  57   // remaining bits in the current byte.
  58   void ConsumeByteRemainder();
  59
  60   // Accessors for testing.
  61
  62   void SetBitOffsetForTest(size_t bit_offset) {
  63     bit_offset_ = bit_offset;
  64   }
  65
  66  private:
  67   const uint32 max_string_literal_size_;
  68   base::StringPiece buffer_;
  69   size_t bit_offset_;
  70
  71   bool PeekNextOctet(uint8* next_octet);
  72
  73   bool DecodeNextOctet(uint8* next_octet);
  74
  75   DISALLOW_COPY_AND_ASSIGN(HpackInputStream);
  76 };
  77
  78 }  // namespace net
  79
  80 #endif  // NET_SPDY_HPACK_INPUT_STREAM_H_