Add HpackDecoder2.

net/spdy/hpack/hpack_decoder2.cc

+// 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.
+
+#include "net/spdy/hpack/hpack_decoder2.h"
+
+#include <list>
+#include <utility>
+
+#include "base/logging.h"
+#include "base/strings/string_piece.h"
+#include "net/http2/decoder/decode_buffer.h"
+#include "net/http2/decoder/decode_status.h"
+#include "net/spdy/hpack/hpack_entry.h"
+
+using base::StringPiece;
+
+namespace net {
+
+HpackDecoder2::HpackDecoder2() : hpack_block_decoder_(this) {
+  Reset();
+}
+
+HpackDecoder2::~HpackDecoder2() {}
+
+void HpackDecoder2::Reset() {
+  DVLOG(2) << "HpackDecoder2::Reset";
+  handler_ = nullptr;
+
+  hpack_block_decoder_.Reset();
+  hpack_block_decoder_.set_listener(this);
+
+  total_hpack_bytes_ = 0;
+  total_header_bytes_ = 0;
+  size_update_count_ = 0;
+  header_seen_ = false;
+  in_progress_ = false;
+  error_detected_ = false;
+  header_block_started_ = false;
+
+  name_.Reset();
+  value_.Reset();
+}
+
+void HpackDecoder2::SetErrorDetected() {
+  if (!error_detected_) {
+    DVLOG(2) << "HpackDecoder2::SetErrorDetected";
+    hpack_block_decoder_.set_listener(&no_op_listener_);
+    error_detected_ = true;
+  }
+}
+
+void HpackDecoder2::ApplyHeaderTableSizeSetting(size_t size_setting) {
+  DVLOG(2) << "HpackDecoder2::ApplyHeaderTableSizeSetting";
+  header_table_.SetSettingsHeaderTableSize(size_setting);
+}
+
+// If a SpdyHeadersHandlerInterface is provided, the decoder will emit
+// headers to it rather than accumulating them in a SpdyHeaderBlock.
+void HpackDecoder2::HandleControlFrameHeadersStart(
+    SpdyHeadersHandlerInterface* handler) {
+  DVLOG(2) << "HpackDecoder2::HandleControlFrameHeadersStart";
+  DCHECK(!header_block_started_);
+  handler_ = handler;
+}
+
+// Called as HPACK block fragments arrive. Returns false
+// if an error occurred while decoding the block.
+bool HpackDecoder2::HandleControlFrameHeadersData(const char* headers_data,
+                                                  size_t headers_data_length) {
+  DVLOG(2) << "HpackDecoder2::HandleControlFrameHeadersData: len="
+           << headers_data_length;
+  if (!header_block_started_) {
+    DCHECK_EQ(total_hpack_bytes_, 0u);
+    // Clear the SpdyHeaderBlock here rather than in Reset so that it is NOT
+    // cleared in HandleControlFrameHeadersComplete, which would be before it
+    // could be used.
+    decoded_block_.clear();
+    header_block_started_ = true;
+    if (handler_ != nullptr) {
+      handler_->OnHeaderBlockStart();
+    }
+  }
+
+  // Sometimes we get a call with headers_data==nullptr and
+  // headers_data_length==0, in which case we need to avoid creating
+  // a DecodeBuffer, which would otherwise complain.
+  if (headers_data_length > 0) {
+    DCHECK_NE(headers_data, nullptr);
+    total_hpack_bytes_ += headers_data_length;
+    DecodeBuffer db(headers_data, headers_data_length);
+    DecodeStatus status = hpack_block_decoder_.Decode(&db);
+    switch (status) {
+      case DecodeStatus::kDecodeDone:
+        // We've completed the decoding of headers_data, and it ended at the
+        // boundary between two HPACK block entries, so name_ and value_ are
+        // currently reset.
+        DCHECK_EQ(0u, db.Remaining());
+        in_progress_ = false;
+        break;
+
+      case DecodeStatus::kDecodeInProgress:
+        DCHECK_EQ(0u, db.Remaining());
+        in_progress_ = true;
+        if (!error_detected_) {
+          name_.BufferStringIfUnbuffered();
+          value_.BufferStringIfUnbuffered();
+          EnforceMaxDecodeBufferSize();
+        }
+        break;
+
+      case DecodeStatus::kDecodeError:
+        SetErrorDetected();
+        break;
+    }
+  }
+  return !error_detected_;
+}
+
+// Called after a HPACK block has been completely delivered via
+// HandleControlFrameHeadersData(). Returns false if an error occurred.
+// |compressed_len| if non-null will be set to the size of the encoded
+// buffered block that was accumulated in HandleControlFrameHeadersData(),
+// to support subsequent calculation of compression percentage.
+// Discards the handler supplied at the start of decoding the block.
+// TODO(jamessynge): Determine if compressed_len is needed; it is used to
+// produce UUMA stat Net.SpdyHpackDecompressionPercentage, but only for
+// SPDY3, not HTTP2.
+bool HpackDecoder2::HandleControlFrameHeadersComplete(size_t* compressed_len) {
+  DVLOG(2) << "HpackDecoder2::HandleControlFrameHeadersComplete";
+  if (error_detected_ || in_progress_) {
+    DVLOG(2) << "error_detected_=" << error_detected_
+             << ", in_progress_=" << in_progress_;
+    return false;
+  }
+  if (compressed_len != nullptr) {
+    *compressed_len = total_hpack_bytes_;
+  }
+  if (handler_ != nullptr) {
+    handler_->OnHeaderBlockEnd(total_header_bytes_);
+  }
+  Reset();
+  return true;
+}
+
+const SpdyHeaderBlock& HpackDecoder2::decoded_block() const {
+  return decoded_block_;
+}
+
+void HpackDecoder2::SetHeaderTableDebugVisitor(
+    std::unique_ptr<HpackHeaderTable::DebugVisitorInterface> visitor) {
+  DVLOG(2) << "HpackDecoder2::SetHeaderTableDebugVisitor";
+  header_table_.set_debug_visitor(std::move(visitor));
+}
+
+void HpackDecoder2::set_max_decode_buffer_size_bytes(
+    size_t max_decode_buffer_size_bytes) {
+  DVLOG(2) << "HpackDecoder2::set_max_decode_buffer_size_bytes";
+  max_decode_buffer_size_bytes_ = max_decode_buffer_size_bytes;
+}
+
+void HpackDecoder2::OnIndexedHeader(size_t index) {
+  DVLOG(2) << "HpackDecoder2::OnIndexedHeader: index=" << index;
+  DCHECK(!error_detected_);
+  const HpackEntry* entry = header_table_.GetByIndex(index);
+  if (entry == nullptr) {
+    SetErrorDetected();
+    return;
+  }
+  HandleHeaderRepresentation(entry->name(), entry->value());
+}
+
+void HpackDecoder2::OnStartLiteralHeader(HpackEntryType entry_type,
+                                         size_t maybe_name_index) {
+  DVLOG(2) << "HpackDecoder2::OnStartLiteralHeader: entry_type=" << entry_type
+           << ",  maybe_name_index=" << maybe_name_index;
+  DCHECK(!error_detected_);
+  entry_type_ = entry_type;
+  if (maybe_name_index > 0) {
+    const HpackEntry* entry = header_table_.GetByIndex(maybe_name_index);
+    if (entry == nullptr) {
+      SetErrorDetected();
+      return;
+    } else {
+      // Non-static entries could be evicted, leaving us with a dangling
+      // pointer, so we preemptively copy. This could be avoided if
+      // TryAddEntry would copy the strings prior to performing eviction.
+      name_.Set(entry->name(), entry->IsStatic());
+      name_.BufferStringIfUnbuffered();
+    }
+  }
+}
+
+void HpackDecoder2::OnNameStart(bool huffman_encoded, size_t len) {
+  DVLOG(2) << "HpackDecoder2::OnNameStart: huffman_encoded="
+           << (huffman_encoded ? "true" : "false") << ",  len=" << len;
+  if (len > max_decode_buffer_size_bytes_) {
+    DVLOG(1) << "Name length (" << len << ") is longer than permitted ("
+             << max_decode_buffer_size_bytes_ << ")";
+    SetErrorDetected();
+    return;
+  }
+  name_.OnStart(huffman_encoded, len);
+}
+
+void HpackDecoder2::OnNameData(const char* data, size_t len) {
+  DVLOG(2) << "HpackDecoder2::OnNameData: len=" << len
+           << "\n data: " << StringPiece(data, len);
+  if (error_detected_) {
+    return;
+  }
+  if (!name_.OnData(data, len)) {
+    SetErrorDetected();
+  }
+}
+
+void HpackDecoder2::OnNameEnd() {
+  DVLOG(2) << "HpackDecoder2::OnNameEnd";
+  if (error_detected_) {
+    return;
+  }
+  if (!name_.OnEnd()) {
+    SetErrorDetected();
+  }
+}
+
+void HpackDecoder2::OnValueStart(bool huffman_encoded, size_t len) {
+  DVLOG(2) << "HpackDecoder2::OnValueStart: huffman_encoded="
+           << (huffman_encoded ? "true" : "false") << ",  len=" << len;
+  if (len > max_decode_buffer_size_bytes_) {
+    DVLOG(1) << "Value length (" << len << ") is longer than permitted ("
+             << max_decode_buffer_size_bytes_ << ")";
+    SetErrorDetected();
+    return;
+  }
+  value_.OnStart(huffman_encoded, len);
+}
+
+void HpackDecoder2::OnValueData(const char* data, size_t len) {
+  DVLOG(2) << "HpackDecoder2::OnValueData: len=" << len
+           << "\n data: " << StringPiece(data, len);
+  if (error_detected_) {
+    return;
+  }
+  if (!value_.OnData(data, len)) {
+    SetErrorDetected();
+  }
+}
+
+void HpackDecoder2::OnValueEnd() {
+  DVLOG(2) << "HpackDecoder2::OnValueEnd";
+  if (error_detected_) {
+    return;
+  }
+  if (!value_.OnEnd()) {
+    SetErrorDetected();
+    return;
+  }
+  if (EnforceMaxDecodeBufferSize()) {
+    // All is well.
+    HandleHeaderRepresentation(name_.str(), value_.str());
+    if (entry_type_ == HpackEntryType::kIndexedLiteralHeader) {
+      header_table_.TryAddEntry(name_.str(), value_.str());
+    }
+    name_.Reset();
+    value_.Reset();
+  }
+}
+
+void HpackDecoder2::OnDynamicTableSizeUpdate(size_t size) {
+  DVLOG(2) << "HpackDecoder2::OnDynamicTableSizeUpdate: size=" << size;
+  if (error_detected_) {
+    return;
+  }
+  if (size > header_table_.settings_size_bound()) {
+    DVLOG(1) << "Dynamic Table Size Update with too large a size: " << size
+             << " > " << header_table_.settings_size_bound();
+    SetErrorDetected();
+    return;
+  }
+  if (header_seen_) {
+    DVLOG(1) << "Dynamic Table Size Update seen after a Header";
+    SetErrorDetected();
+    return;
+  }
+  ++size_update_count_;
+  if (size_update_count_ > 2) {
+    DVLOG(1) << "Too many (" << size_update_count_
+             << ") Dynamic Table Size Updates";
+    SetErrorDetected();
+    return;
+  }
+  header_table_.SetMaxSize(size);
+  return;
+}
+
+bool HpackDecoder2::EnforceMaxDecodeBufferSize() {
+  if (!error_detected_) {
+    size_t buffered_length = name_.BufferedLength() + value_.BufferedLength();
+    DVLOG(2) << "buffered_length=" << buffered_length
+             << "; max=" << max_decode_buffer_size_bytes_;
+    if (buffered_length > max_decode_buffer_size_bytes_) {
+      DVLOG(1) << "Header length (" << buffered_length
+               << ") is longer than permitted ("
+               << max_decode_buffer_size_bytes_ << ")";
+      SetErrorDetected();
+    }
+  }
+  return !error_detected_;
+}
+
+void HpackDecoder2::HandleHeaderRepresentation(StringPiece name,
+                                               StringPiece value) {
+  DVLOG(2) << "HpackDecoder2::HandleHeaderRepresentation:\n name: " << name
+           << "\n value: " << value;
+  total_header_bytes_ += name.size() + value.size();
+  header_seen_ = true;
+  if (handler_ == nullptr) {
+    DVLOG(3) << "HpackDecoder2::HandleHeaderRepresentation "
+             << "adding to decoded_block";
+    decoded_block_.AppendValueOrAddHeader(name, value);
+  } else {
+    DVLOG(3) << "HpackDecoder2::HandleHeaderRepresentation "
+             << "passing to handler";
+    DCHECK(decoded_block_.empty());
+    handler_->OnHeader(name, value);
+  }
+}
+
+}  // namespace net