Add HpackDecoderTables, static and dynamic tables for decoding HPACK.

net/http2/hpack/decoder/hpack_decoder_tables.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/http2/hpack/decoder/hpack_decoder_tables.h"
+
+#include "base/logging.h"
+
+namespace net {
+namespace {
+
+std::vector<HpackStringPair>* MakeStaticTable() {
+  auto ptr = new std::vector<HpackStringPair>();
+  ptr->reserve(kFirstDynamicTableIndex);
+  ptr->emplace_back("", "");
+
+#define STATIC_TABLE_ENTRY(name, value, index) \
+  DCHECK_EQ(ptr->size(), index);               \
+  ptr->emplace_back(name, value)
+
+#include "net/http2/hpack/hpack_static_table_entries.inc"
+
+#undef STATIC_TABLE_ENTRY
+
+  return ptr;
+}
+
+const std::vector<HpackStringPair>* GetStaticTable() {
+  static const std::vector<HpackStringPair>* const g_static_table =
+      MakeStaticTable();
+  return g_static_table;
+}
+
+}  // namespace
+
+HpackDecoderStaticTable::HpackDecoderStaticTable(
+    const std::vector<HpackStringPair>* table)
+    : table_(table) {}
+
+HpackDecoderStaticTable::HpackDecoderStaticTable() : table_(GetStaticTable()) {}
+
+const HpackStringPair* HpackDecoderStaticTable::Lookup(size_t index) const {
+  if (0 < index && index < kFirstDynamicTableIndex) {
+    return &((*table_)[index]);
+  }
+  return nullptr;
+}
+
+HpackDecoderDynamicTable::HpackDecoderDynamicTable() {}
+HpackDecoderDynamicTable::~HpackDecoderDynamicTable() {}
+
+void HpackDecoderDynamicTable::DynamicTableSizeUpdate(size_t size_limit) {
+  EnsureSizeNoMoreThan(size_limit);
+  DCHECK_LE(current_size_, size_limit);
+  size_limit_ = size_limit;
+}
+
+// TODO(jamessynge): Check somewhere before here that names received from the
+// peer are valid (e.g. are lower-case, no whitespace, etc.).
+bool HpackDecoderDynamicTable::Insert(const HpackString& name,
+                                      const HpackString& value) {
+  HpackStringPair p(name, value);
+  size_t entry_size = p.size();
+  DVLOG(2) << "InsertEntry of size=" << entry_size << "\n     name: " << name
+           << "\n    value: " << value;
+  if (entry_size > size_limit_) {
+    DVLOG(2) << "InsertEntry: entry larger than table, removing "
+             << table_.size() << " entries, of total size " << current_size_
+             << " bytes.";
+    table_.clear();
+    current_size_ = 0;
+    return false;  // Not inserted because too large.
+  }
+  size_t insert_limit = size_limit_ - entry_size;
+  EnsureSizeNoMoreThan(insert_limit);
+  table_.push_front(p);
+  current_size_ += entry_size;
+  DVLOG(2) << "InsertEntry: current_size_=" << current_size_;
+  DCHECK_GE(current_size_, entry_size);
+  DCHECK_LE(current_size_, size_limit_);
+  return true;
+}
+
+const HpackStringPair* HpackDecoderDynamicTable::Lookup(size_t index) const {
+  if (index < table_.size()) {
+    return &(table_[index]);
+  }
+  return nullptr;
+}
+
+void HpackDecoderDynamicTable::EnsureSizeNoMoreThan(size_t limit) {
+  DVLOG(2) << "EnsureSizeNoMoreThan limit=" << limit
+           << ", current_size_=" << current_size_;
+  // Not the most efficient choice, but any easy way to start.
+  while (current_size_ > limit) {
+    RemoveLastEntry();
+  }
+  DCHECK_LE(current_size_, limit);
+}
+
+void HpackDecoderDynamicTable::RemoveLastEntry() {
+  DCHECK(!table_.empty());
+  if (!table_.empty()) {
+    DVLOG(2) << "RemoveLastEntry current_size_=" << current_size_
+             << ", last entry size=" << table_.back().size();
+    DCHECK_GE(current_size_, table_.back().size());
+    current_size_ -= table_.back().size();
+    table_.pop_back();
+    // Empty IFF current_size_ == 0.
+    DCHECK_EQ(table_.empty(), current_size_ == 0);
+  }
+}
+
+HpackDecoderTables::HpackDecoderTables() {}
+HpackDecoderTables::~HpackDecoderTables() {}
+
+}  // namespace net