net/spdy/hpack_output_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_OUTPUT_STREAM_H_
   6 #define NET_SPDY_HPACK_OUTPUT_STREAM_H_
   7
   8 #include <map>
   9 #include <string>
  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"  // For HpackPrefix.
  16 #include "net/spdy/hpack_encoding_context.h"
  17
  18 // All section references below are to
  19 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-06
  20
  21 namespace net {
  22
  23 // An HpackOutputStream handles all the low-level details of encoding
  24 // header fields.
  25 class NET_EXPORT_PRIVATE HpackOutputStream {
  26  public:
  27   // |max_string_literal_size| is the largest that any one string
  28   // |literal (header name or header value) can be.
  29   explicit HpackOutputStream(uint32 max_string_literal_size);
  30   ~HpackOutputStream();
  31
  32   // Corresponds to 4.2.
  33   void AppendIndexedHeader(uint32 index_or_zero);
  34
  35   // Corresponds to 4.3.1 (second form). Returns whether or not the
  36   // append was successful; if the append was unsuccessful, no other
  37   // member function may be called.
  38   bool AppendLiteralHeaderNoIndexingWithName(base::StringPiece name,
  39                                              base::StringPiece value);
  40
  41   // Moves the internal buffer to the given string and clears all
  42   // internal state.
  43   void TakeString(std::string* output);
  44
  45   // Appends the lower |bit_size| bits of |bits| to the internal buffer.
  46   //
  47   // |bit_size| must be > 0 and <= 8. |bits| must not have any bits
  48   // set other than the lower |bit_size| bits.
  49   void AppendBits(uint8 bits, size_t bit_size);
  50
  51   // Accessors for testing.
  52
  53   void AppendBitsForTest(uint8 bits, size_t size) {
  54     AppendBits(bits, size);
  55   }
  56
  57   void AppendUint32ForTest(uint32 I) {
  58     AppendUint32(I);
  59   }
  60
  61   bool AppendStringLiteralForTest(base::StringPiece str) {
  62     return AppendStringLiteral(str);
  63   }
  64
  65  private:
  66   // Simply forwards to AppendBits(prefix.bits, prefix.bit-size).
  67   void AppendPrefix(HpackPrefix prefix);
  68
  69   // Appends the given integer using the representation described in
  70   // 4.1.1. If the internal buffer ends on a byte boundary, the prefix
  71   // length N is taken to be 8; otherwise, it is taken to be the
  72   // number of bits to the next byte boundary.
  73   //
  74   // It is guaranteed that the internal buffer will end on a byte
  75   // boundary after this function is called.
  76   void AppendUint32(uint32 I);
  77
  78   // Appends the given string using the representation described in
  79   // 4.1.2. The internal buffer must end on a byte boundary, and it is
  80   // guaranteed that the internal buffer will end on a byte boundary
  81   // after this function is called. Returns whether or not the append
  82   // was successful; if the append was unsuccessful, no other member
  83   // function may be called.
  84   bool AppendStringLiteral(base::StringPiece str);
  85
  86   const uint32 max_string_literal_size_;
  87
  88   // The internal bit buffer.
  89   std::string buffer_;
  90
  91   // If 0, the buffer ends on a byte boundary. If non-zero, the buffer
  92   // ends on the most significant nth bit. Guaranteed to be < 8.
  93   size_t bit_offset_;
  94
  95   DISALLOW_COPY_AND_ASSIGN(HpackOutputStream);
  96 };
  97
  98 }  // namespace net
  99
 100 #endif  // NET_SPDY_HPACK_OUTPUT_STREAM_H_