net/spdy/hpack/hpack_encoder.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_ENCODER_H_
   6 #define NET_SPDY_HPACK_ENCODER_H_
   7
   8 #include <map>
   9 #include <string>
  10 #include <utility>
  11 #include <vector>
  12
  13 #include "base/basictypes.h"
  14 #include "base/macros.h"
  15 #include "base/strings/string_piece.h"
  16 #include "net/base/net_export.h"
  17 #include "net/spdy/hpack/hpack_header_table.h"
  18 #include "net/spdy/hpack/hpack_output_stream.h"
  19 #include "net/spdy/spdy_protocol.h"
  20
  21 // An HpackEncoder encodes header sets as outlined in
  22 // http://tools.ietf.org/html/rfc7541.
  23
  24 namespace net {
  25
  26 class HpackHuffmanTable;
  27
  28 namespace test {
  29 class HpackEncoderPeer;
  30 }  // namespace test
  31
  32 class NET_EXPORT_PRIVATE HpackEncoder {
  33  public:
  34   friend class test::HpackEncoderPeer;
  35
  36   // |table| is an initialized HPACK Huffman table, having an
  37   // externally-managed lifetime which spans beyond HpackEncoder.
  38   explicit HpackEncoder(const HpackHuffmanTable& table);
  39   ~HpackEncoder();
  40
  41   // Encodes the given header set into the given string. Returns
  42   // whether or not the encoding was successful.
  43   bool EncodeHeaderSet(const SpdyHeaderBlock& header_set, std::string* output);
  44
  45   // Encodes the given header set into the given string. Only non-indexed
  46   // literal representations are emitted, bypassing the header table. Huffman
  47   // coding is also not used. Returns whether the encoding was successful.
  48   bool EncodeHeaderSetWithoutCompression(const SpdyHeaderBlock& header_set,
  49                                          std::string* output);
  50
  51   // Called upon a change to SETTINGS_HEADER_TABLE_SIZE. Specifically, this
  52   // is to be called after receiving (and sending an acknowledgement for) a
  53   // SETTINGS_HEADER_TABLE_SIZE update from the remote decoding endpoint.
  54   void ApplyHeaderTableSizeSetting(size_t size_setting) {
  55     header_table_.SetSettingsHeaderTableSize(size_setting);
  56   }
  57
  58   // Sets externally-owned storage for aggregating character counts of emitted
  59   // literal representations.
  60   void SetCharCountsStorage(std::vector<size_t>* char_counts,
  61                             size_t* total_char_counts);
  62
  63  private:
  64   typedef std::pair<base::StringPiece, base::StringPiece> Representation;
  65   typedef std::vector<Representation> Representations;
  66
  67   // Emits a static/dynamic indexed representation (Section 7.1).
  68   void EmitIndex(const HpackEntry* entry);
  69
  70   // Emits a literal representation (Section 7.2).
  71   void EmitIndexedLiteral(const Representation& representation);
  72   void EmitNonIndexedLiteral(const Representation& representation);
  73   void EmitLiteral(const Representation& representation);
  74
  75   // Emits a Huffman or identity string (whichever is smaller).
  76   void EmitString(base::StringPiece str);
  77
  78   void UpdateCharacterCounts(base::StringPiece str);
  79
  80   // Crumbles a cookie header into ";" delimited crumbs.
  81   static void CookieToCrumbs(const Representation& cookie,
  82                              Representations* crumbs_out);
  83
  84   // Crumbles other header field values at \0 delimiters.
  85   static void DecomposeRepresentation(const Representation& header_field,
  86                                       Representations* out);
  87
  88   HpackHeaderTable header_table_;
  89   HpackOutputStream output_stream_;
  90
  91   bool allow_huffman_compression_;
  92   const HpackHuffmanTable& huffman_table_;
  93
  94   // Externally-owned, nullable storage for character counts of literals.
  95   std::vector<size_t>* char_counts_;
  96   size_t* total_char_counts_;
  97
  98   DISALLOW_COPY_AND_ASSIGN(HpackEncoder);
  99 };
 100
 101 }  // namespace net
 102
 103 #endif  // NET_SPDY_HPACK_ENCODER_H_