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 #include <vector>
  10
  11 #include "base/basictypes.h"
  12 #include "base/macros.h"
  13 #include "base/strings/string_piece.h"
  14 #include "net/base/net_export.h"
  15 #include "net/spdy/hpack_constants.h"
  16 #include "net/spdy/hpack_huffman_table.h"
  17
  18 // All section references below are to
  19 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-05
  20
  21 namespace net {
  22
  23 // TODO(akalin): When we use a callback/delegate instead of a vector,
  24 // use StringPiece instead of string.
  25 typedef std::pair<std::string, std::string> HpackHeaderPair;
  26 typedef std::vector<HpackHeaderPair> HpackHeaderPairVector;
  27
  28 // An HpackInputStream handles all the low-level details of decoding
  29 // header fields.
  30 class NET_EXPORT_PRIVATE HpackInputStream {
  31  public:
  32   // |max_string_literal_size| is the largest that any one string
  33   // literal (header name or header value) can be.
  34   HpackInputStream(uint32 max_string_literal_size, base::StringPiece buffer);
  35   ~HpackInputStream();
  36
  37   // Returns whether or not there is more data to process.
  38   bool HasMoreData() const;
  39
  40   // If the next octet has the top |size| bits equal to |bits|,
  41   // consumes it and returns true. Otherwise, consumes nothing and
  42   // returns false.
  43   bool MatchPrefixAndConsume(HpackPrefix prefix);
  44
  45   // The Decode* functions return true and fill in their arguments if
  46   // decoding was successful, or false if an error was encountered.
  47
  48   bool DecodeNextUint32(uint32* I);
  49   bool DecodeNextIdentityString(base::StringPiece* str);
  50   bool DecodeNextHuffmanString(const HpackHuffmanTable& table,
  51                                std::string* str);
  52
  53   // Stores input bits into the most-significant, unfilled bits of |out|.
  54   // |peeked_count| is the number of filled bits in |out| which have been
  55   // previously peeked. PeekBits() will fill some number of remaining bits,
  56   // returning the new total number via |peeked_count|. Returns true if one
  57   // or more additional bits could be peeked, and false otherwise.
  58   bool PeekBits(size_t* peeked_count, uint32* out);
  59
  60   // Consumes |count| bits of input. Generally paired with PeekBits().
  61   void ConsumeBits(size_t count);
  62
  63   // If not currently on a byte boundary, consumes and discards
  64   // remaining bits in the current byte.
  65   void ConsumeByteRemainder();
  66
  67   // Accessors for testing.
  68
  69   void SetBitOffsetForTest(size_t bit_offset) {
  70     bit_offset_ = bit_offset;
  71   }
  72
  73   bool DecodeNextUint32ForTest(uint32* I) {
  74     return DecodeNextUint32(I);
  75   }
  76
  77  private:
  78   const uint32 max_string_literal_size_;
  79   base::StringPiece buffer_;
  80   size_t bit_offset_;
  81
  82   bool PeekNextOctet(uint8* next_octet);
  83
  84   bool DecodeNextOctet(uint8* next_octet);
  85
  86   DISALLOW_COPY_AND_ASSIGN(HpackInputStream);
  87 };
  88
  89 }  // namespace net
  90
  91 #endif  // NET_SPDY_HPACK_INPUT_STREAM_H_