Add HpackDecoder2.

net/spdy/hpack/hpack_decoder2.h

+// Copyright 2016 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_HPACK_DECODER2_H_
+#define NET_SPDY_HPACK_HPACK_DECODER2_H_
+
+// HpackDecoder2
+
+// An HpackDecoder decodes header sets as outlined in
+// http://tools.ietf.org/html/rfc7541. This implementation uses the
+// new HpackBlockDecoder in //net/http2/hpack/
+
+#include <stddef.h>
+
+#include <memory>
+#include <string>
+
+#include "base/macros.h"
+#include "base/strings/string_piece.h"
+#include "net/base/net_export.h"
+#include "net/http2/hpack/decoder/hpack_block_decoder.h"
+#include "net/http2/hpack/decoder/hpack_decoder_string_buffer.h"
+#include "net/http2/hpack/decoder/hpack_entry_decoder_listener.h"
+#include "net/http2/hpack/http2_hpack_constants.h"
+#include "net/http2/hpack/huffman/http2_hpack_huffman_decoder.h"
+#include "net/spdy/hpack/hpack_constants.h"
+#include "net/spdy/hpack/hpack_decoder_interface.h"
+#include "net/spdy/hpack/hpack_header_table.h"
+#include "net/spdy/spdy_header_block.h"
+#include "net/spdy/spdy_headers_handler_interface.h"
+
+namespace net {
+namespace test {
+class HpackDecoder2Peer;
+}  // namespace test
+
+class NET_EXPORT_PRIVATE HpackDecoder2 : public HpackDecoderInterface,
+                                         HpackEntryDecoderListener {
+ public:
+  friend test::HpackDecoder2Peer;
+  HpackDecoder2();
+  ~HpackDecoder2() override;
+
+  // Override the interface methods:
+
+  void ApplyHeaderTableSizeSetting(size_t size_setting) override;
+  void HandleControlFrameHeadersStart(
+      SpdyHeadersHandlerInterface* handler) override;
+  bool HandleControlFrameHeadersData(const char* headers_data,
+                                     size_t headers_data_length) override;
+  bool HandleControlFrameHeadersComplete(size_t* compressed_len) override;
+  const SpdyHeaderBlock& decoded_block() const override;
+  void SetHeaderTableDebugVisitor(
+      std::unique_ptr<HpackHeaderTable::DebugVisitorInterface> visitor)
+      override;
+  void set_max_decode_buffer_size_bytes(
+      size_t max_decode_buffer_size_bytes) override;
+
+ protected:
+  // Override the HpackEntryDecoderListener methods:
+
+  void OnIndexedHeader(size_t index) override;
+  void OnStartLiteralHeader(HpackEntryType entry_type,
+                            size_t maybe_name_index) override;
+  void OnNameStart(bool huffman_encoded, size_t len) override;
+  void OnNameData(const char* data, size_t len) override;
+  void OnNameEnd() override;
+  void OnValueStart(bool huffman_encoded, size_t len) override;
+  void OnValueData(const char* data, size_t len) override;
+  void OnValueEnd() override;
+  void OnDynamicTableSizeUpdate(size_t size) override;
+
+ private:
+  // Called when a complete header entry has been decoded, with the name and
+  // value of the entry. If check_header_order_ is true, confirms that
+  // pseudo-headers don't appear after normal headers, else it treats the
+  // headers as malformed, as per sections 8.1.2.3. of the HTTP2 specification.
+  // Calls handler_->OnHeader() if there is a handler, else adds the header
+  // to decoded_block_.
+  void HandleHeaderRepresentation(base::StringPiece name,
+                                  base::StringPiece value);
+
+  // Reset state in preparation for decoding a new HPACK block. Does not reset
+  // the dynamic table.
+  void Reset();
+
+  // Called when an error is detected while decoding. Replaces the listener
+  // in the HpackBlockDecoder with the no-op listener.
+  void SetErrorDetected();
+
+  // Enforce the limit on the maximum size of strings that can be buffered.
+  // It happens that this test is made after the strings have been buffered,
+  // but that isn't a problem because we don't pass enormous buffers into
+  // HandleControlFrameHeadersData.
+  bool EnforceMaxDecodeBufferSize();
+
+  HpackHeaderTable header_table_;
+  SpdyHeaderBlock decoded_block_;
+
+  // Scratch space for storing decoded literals.
+  HpackDecoderStringBuffer name_, value_;
+
+  // If non-NULL, handles decoded headers.
+  SpdyHeadersHandlerInterface* handler_;
+
+  HpackEntryDecoderNoOpListener no_op_listener_;
+
+  // Total bytes that have been received as input (i.e. HPACK encoded).
+  size_t total_hpack_bytes_;
+
+  // Total bytes of the name and value strings in the current HPACK block.
+  size_t total_header_bytes_;
+
+  // How much encoded data this decoder is willing to buffer.
+  size_t max_decode_buffer_size_bytes_ = 32 * 1024;  // 32 KB
+
+  HpackBlockDecoder hpack_block_decoder_;
+
+  // Count of Dynamic Table Size Updates seen in the current HPACK block.
+  uint32_t size_update_count_;
+
+  // The type of the current header entry (with literals) that is being decoded.
+  HpackEntryType entry_type_;
+
+  // Has a header been seen in the current HPACK block?
+  bool header_seen_;
+
+  // Did the HpackBlockDecoder stop in the middle of an entry?
+  bool in_progress_;
+
+  // Has an error been detected while decoding the HPACK block?
+  bool error_detected_;
+
+  // Flag to keep track of having seen the header block start. Needed at the
+  // moment because HandleControlFrameHeadersStart won't be called if a handler
+  // is not being provided by the caller.
+  // TODO(jamessynge): Consider collapsing several of these bools into a single
+  // enum representing the state of the decoding process.
+  bool header_block_started_;
+
+  DISALLOW_COPY_AND_ASSIGN(HpackDecoder2);
+};
+
+}  // namespace net
+#endif  // NET_SPDY_HPACK_HPACK_DECODER2_H_