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

net/http2/hpack/tools/hpack_block_builder.cc

Index: net/http2/hpack/tools/hpack_block_builder.cc
diff --git a/net/http2/hpack/tools/hpack_block_builder.cc b/net/http2/hpack/tools/hpack_block_builder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..49eba0d67195e5521cd1ea837c606f5eb8f1a553
--- /dev/null
+++ b/net/http2/hpack/tools/hpack_block_builder.cc
@@ -0,0 +1,84 @@
+// 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/tools/hpack_block_builder.h"
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+namespace test {
+
+void HpackBlockBuilder::AppendHighBitsAndVarint(uint8_t high_bits,
+                                                uint8_t prefix_length,
+                                                uint64_t varint) {
+  EXPECT_LE(4, prefix_length);
+  EXPECT_LE(prefix_length, 7);
+
+  // prefix_mask defines the sequence of low-order bits of the first byte
+  // that encode the prefix of the value. It is also the marker in those bits
+  // of the first byte indicating that at least one extension byte is needed.
+  uint8_t prefix_mask = (1 << prefix_length) - 1;
+  EXPECT_EQ(0, high_bits & prefix_mask);
+
+  if (varint < prefix_mask) {
+    uint8_t b = high_bits | static_cast<uint8_t>(varint);
+    buffer_.push_back(static_cast<char>(b));
+    return;
+  }
+
+  // We need extension bytes.
+  buffer_.push_back(static_cast<char>(high_bits | prefix_mask));
+  varint -= prefix_mask;
+  while (varint >= 128) {
+    uint8_t b = static_cast<uint8_t>((varint % 128) + 128);
+    buffer_.push_back(static_cast<char>(b));
+    varint = varint / 128;
+  }
+  char c = static_cast<char>(varint);
+  buffer_.push_back(c);
+}
+
+void HpackBlockBuilder::AppendEntryTypeAndVarint(HpackEntryType entry_type,
+                                                 uint64_t varint) {
+  uint8_t high_bits;
+  uint8_t prefix_length;  // Bits of the varint prefix in the first byte.
+  switch (entry_type) {
+    case HpackEntryType::kIndexedHeader:
+      high_bits = 0x80;
+      prefix_length = 7;
+      break;
+    case HpackEntryType::kDynamicTableSizeUpdate:
+      high_bits = 0x20;
+      prefix_length = 5;
+      break;
+    case HpackEntryType::kIndexedLiteralHeader:
+      high_bits = 0x40;
+      prefix_length = 6;
+      break;
+    case HpackEntryType::kUnindexedLiteralHeader:
+      high_bits = 0x00;
+      prefix_length = 4;
+      break;
+    case HpackEntryType::kNeverIndexedLiteralHeader:
+      high_bits = 0x10;
+      prefix_length = 4;
+      break;
+    default:
+      NOTREACHED();
+      high_bits = 0;
+      prefix_length = 0;
+  }
+  AppendHighBitsAndVarint(high_bits, prefix_length, varint);
+}
+
+void HpackBlockBuilder::AppendString(bool is_huffman_encoded,
+                                     base::StringPiece str) {
+  uint8_t high_bits = is_huffman_encoded ? 0x80 : 0;
+  uint8_t prefix_length = 7;
+  AppendHighBitsAndVarint(high_bits, prefix_length, str.size());
+  str.AppendToString(&buffer_);
+}
+
+}  // namespace test
+}  // namespace net