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-05
  20 // .
  21
  22 namespace net {
  23
  24 // An HpackOutputStream handles all the low-level details of encoding
  25 // header fields.
  26 class NET_EXPORT_PRIVATE HpackOutputStream {
  27  public:
  28   // |max_string_literal_size| is the largest that any one string
  29   // |literal (header name or header value) can be.
  30   explicit HpackOutputStream(uint32 max_string_literal_size);
  31   ~HpackOutputStream();
  32
  33   // Corresponds to 4.2.
  34   void AppendIndexedHeader(uint32 index_or_zero);
  35
  36   // Corresponds to 4.3.1 (second form). Returns whether or not the
  37   // append was successful; if the append was unsuccessful, no other
  38   // member function may be called.
  39   bool AppendLiteralHeaderNoIndexingWithName(base::StringPiece name,
  40                                              base::StringPiece value);
  41
  42   // Moves the internal buffer to the given string and clears all
  43   // internal state.
  44   void TakeString(std::string* output);
  45
  46   // Appends the lower |bit_size| bits of |bits| to the internal buffer.
  47   //
  48   // |bit_size| must be > 0 and <= 8. |bits| must not have any bits
  49   // set other than the lower |bit_size| bits.
  50   void AppendBits(uint8 bits, size_t bit_size);
  51
  52   // Accessors for testing.
  53
  54   void AppendBitsForTest(uint8 bits, size_t size) {
  55     AppendBits(bits, size);
  56   }
  57
  58   void AppendUint32ForTest(uint32 I) {
  59     AppendUint32(I);
  60   }
  61
  62   bool AppendStringLiteralForTest(base::StringPiece str) {
  63     return AppendStringLiteral(str);
  64   }
  65
  66  private:
  67   // Simply forwards to AppendBits(prefix.bits, prefix.bit-size).
  68   void AppendPrefix(HpackPrefix prefix);
  69
  70   // Appends the given integer using the representation described in
  71   // 4.1.1. If the internal buffer ends on a byte boundary, the prefix
  72   // length N is taken to be 8; otherwise, it is taken to be the
  73   // number of bits to the next byte boundary.
  74   //
  75   // It is guaranteed that the internal buffer will end on a byte
  76   // boundary after this function is called.
  77   void AppendUint32(uint32 I);
  78
  79   // Appends the given string using the representation described in
  80   // 4.1.2. The internal buffer must end on a byte boundary, and it is
  81   // guaranteed that the internal buffer will end on a byte boundary
  82   // after this function is called. Returns whether or not the append
  83   // was successful; if the append was unsuccessful, no other member
  84   // function may be called.
  85   bool AppendStringLiteral(base::StringPiece str);
  86
  87   const uint32 max_string_literal_size_;
  88
  89   // The internal bit buffer.
  90   std::string buffer_;
  91
  92   // If 0, the buffer ends on a byte boundary. If non-zero, the buffer
  93   // ends on the most significant nth bit. Guaranteed to be < 8.
  94   size_t bit_offset_;
  95
  96   DISALLOW_COPY_AND_ASSIGN(HpackOutputStream);
  97 };
  98
  99 }  // namespace net
 100
 101 #endif  // NET_SPDY_HPACK_OUTPUT_STREAM_H_