Implements incremental decode in HPACK.

net/spdy/hpack/hpack_input_stream.h

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_SPDY_HPACK_INPUT_STREAM_H_
 #define NET_SPDY_HPACK_INPUT_STREAM_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <string>
 #include <utility>
 
 #include "base/macros.h"
 #include "base/strings/string_piece.h"
 #include "net/base/net_export.h"
 #include "net/spdy/hpack/hpack_constants.h"
 #include "net/spdy/hpack/hpack_huffman_table.h"
 
 // All section references below are to
 // http://tools.ietf.org/html/draft-ietf-httpbis-header-compression-08
 
 namespace net {
 
+namespace test {
+class HpackInputStreamPeer;
+}  // namespace test
+
 typedef std::pair<size_t, uint32_t> InitialPeekResult;
 
 // An HpackInputStream handles all the low-level details of decoding
 // header fields.
 class NET_EXPORT_PRIVATE HpackInputStream {
  public:
+  friend class test::HpackInputStreamPeer;
+
   // |max_string_literal_size| is the largest that any one string
   // literal (header name or header value) can be.
   HpackInputStream(uint32_t max_string_literal_size, base::StringPiece buffer);
   ~HpackInputStream();
 
   // Returns whether or not there is more data to process.
   bool HasMoreData() const;
 
   // If the next bits of input match |prefix|, consumes them and returns true.
   // Otherwise, consumes nothing and returns false.
@@ skipping 24 matching lines @@
   // PeekBits.
   InitialPeekResult InitializePeekBits();
 
   // Consumes |count| bits of input. Generally paired with PeekBits().
   void ConsumeBits(size_t count);
 
   // If not currently on a byte boundary, consumes and discards
   // remaining bits in the current byte.
   void ConsumeByteRemainder();
 
-  // Accessors for testing.
+  // Return the total bytes that have been parsed SUCCESSFULLY.
+  uint32_t ParsedBytes() const;
 
-  void SetBitOffsetForTest(size_t bit_offset) { bit_offset_ = bit_offset; }
+  // When incrementally decode the header, need to remember the current
+  // position in the buffer after we successfully decode one opcode.
+  void MarkCurrentPosition();
+
+  // Returning true indicates this instance of HpackInputStream
+  // doesn't have enough data to parse the current opcode, and we
+  // are done with this instance. When more data arrive, a new
+  // HpackInputStream should be created to restart the parsing.
+  bool NeedMoreData() const;
 
  private:
   const uint32_t max_string_literal_size_;
   base::StringPiece buffer_;
   size_t bit_offset_;
+  // Total number of bytes parsed successfully. Only get updated when an
+  // opcode is parsed successfully.
+  uint32_t parsed_bytes_;
+  // Total number of bytes parsed currently. Get updated when an octet,
+  // a number or a string has been parsed successfully. Can point to the
+  // middle of an opcode.
+  uint32_t parsed_bytes_current_;
+  bool need_more_data_;
 
   bool PeekNextOctet(uint8_t* next_octet);
 
   bool DecodeNextOctet(uint8_t* next_octet);
 
   DISALLOW_COPY_AND_ASSIGN(HpackInputStream);
 };
 
 }  // namespace net
 
 #endif  // NET_SPDY_HPACK_INPUT_STREAM_H_