Add new HTTP/2 and HPACK decoder in net/http2/.

net/http2/hpack/tools/hpack_block_builder.h

Index: net/http2/hpack/tools/hpack_block_builder.h
diff --git a/net/http2/hpack/tools/hpack_block_builder.h b/net/http2/hpack/tools/hpack_block_builder.h
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+++ b/net/http2/hpack/tools/hpack_block_builder.h
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+// 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_HTTP2_HPACK_TOOLS_HPACK_BLOCK_BUILDER_H_
+#define NET_HTTP2_HPACK_TOOLS_HPACK_BLOCK_BUILDER_H_
+
+// HpackBlockBuilder builds wire-format HPACK blocks (or fragments thereof)
+// from components.
+
+// Supports very large varints to enable tests to create HPACK blocks with
+// values that the decoder should reject. For now, this is only intended for
+// use in tests, and thus has EXPECT* in the code. If desired to use it in an
+// encoder, it will need optimization work, especially w.r.t memory mgmt, and
+// the EXPECT* will need to be removed or replaced with DCHECKs. And of course
+// the support for very large varints will not be needed in production code.
+
+#include <stddef.h>
+#include <string>
+
+#include "base/strings/string_piece.h"
+#include "net/http2/hpack/http2_hpack_constants.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+namespace test {
+
+class HpackBlockBuilder {
+ public:
+  explicit HpackBlockBuilder(base::StringPiece initial_contents) {
+    initial_contents.AppendToString(&buffer_);
+  }
+  HpackBlockBuilder() {}
+  ~HpackBlockBuilder() {}
+
+  size_t size() const { return buffer_.size(); }
+  const std::string& buffer() const { return buffer_; }
+
+  //----------------------------------------------------------------------------
+  // Methods for appending a valid HPACK entry.
+
+  void AppendIndexedHeader(uint64_t index) {
+    AppendEntryTypeAndVarint(HpackEntryType::kIndexedHeader, index);
+  }
+
+  void AppendDynamicTableSizeUpdate(uint64_t size) {
+    AppendEntryTypeAndVarint(HpackEntryType::kDynamicTableSizeUpdate, size);
+  }
+
+  void AppendNameIndexAndLiteralValue(HpackEntryType entry_type,
+                                      uint64_t name_index,
+                                      bool value_is_huffman_encoded,
+                                      base::StringPiece value) {
+    // name_index==0 would indicate that the entry includes a literal name.
+    // Call AppendLiteralNameAndValue in that case.
+    EXPECT_NE(0u, name_index);
+    AppendEntryTypeAndVarint(entry_type, name_index);
+    AppendString(value_is_huffman_encoded, value);
+  }
+
+  void AppendLiteralNameAndValue(HpackEntryType entry_type,
+                                 bool name_is_huffman_encoded,
+                                 base::StringPiece name,
+                                 bool value_is_huffman_encoded,
+                                 base::StringPiece value) {
+    AppendEntryTypeAndVarint(entry_type, 0);
+    AppendString(name_is_huffman_encoded, name);
+    AppendString(value_is_huffman_encoded, value);
+  }
+
+  //----------------------------------------------------------------------------
+  // Primitive methods that are not guaranteed to write a valid HPACK entry.
+
+  // Appends a varint, with the specified high_bits above the prefix of the
+  // varint.
+  void AppendHighBitsAndVarint(uint8_t high_bits,
+                               uint8_t prefix_length,
+                               uint64_t varint);
+
+  // Append the start of an HPACK entry for the specified type, with the
+  // specified varint.
+  void AppendEntryTypeAndVarint(HpackEntryType entry_type, uint64_t varint);
+
+  // Append a header string (i.e. a header name or value) in HPACK format.
+  // Does NOT perform Huffman encoding.
+  void AppendString(bool is_huffman_encoded, base::StringPiece str);
+
+ private:
+  std::string buffer_;
+};
+
+}  // namespace test
+}  // namespace net
+
+#endif  // NET_HTTP2_HPACK_TOOLS_HPACK_BLOCK_BUILDER_H_