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

net/http2/hpack/decoder/hpack_decoder_string_buffer.cc

Index: net/http2/hpack/decoder/hpack_decoder_string_buffer.cc
diff --git a/net/http2/hpack/decoder/hpack_decoder_string_buffer.cc b/net/http2/hpack/decoder/hpack_decoder_string_buffer.cc
new file mode 100644
index 0000000000000000000000000000000000000000..90d03365422bfd6c2a833eba2d5a4cbdb2076385
--- /dev/null
+++ b/net/http2/hpack/decoder/hpack_decoder_string_buffer.cc
@@ -0,0 +1,215 @@
+// 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_string_buffer.h"
+
+#include "base/logging.h"
+
+using base::StringPiece;
+
+namespace net {
+
+std::ostream& operator<<(std::ostream& out,
+                         const HpackDecoderStringBuffer::State v) {
+  switch (v) {
+    case HpackDecoderStringBuffer::State::RESET:
+      return out << "RESET";
+    case HpackDecoderStringBuffer::State::COLLECTING:
+      return out << "COLLECTING";
+    case HpackDecoderStringBuffer::State::COMPLETE:
+      return out << "COMPLETE";
+    default:
+      return out << "Unknown HpackDecoderStringBuffer::State!";
+  }
+}
+
+std::ostream& operator<<(std::ostream& out,
+                         const HpackDecoderStringBuffer::Backing v) {
+  switch (v) {
+    case HpackDecoderStringBuffer::Backing::RESET:
+      return out << "RESET";
+    case HpackDecoderStringBuffer::Backing::UNBUFFERED:
+      return out << "UNBUFFERED";
+    case HpackDecoderStringBuffer::Backing::BUFFERED:
+      return out << "BUFFERED";
+    case HpackDecoderStringBuffer::Backing::STATIC:
+      return out << "STATIC";
+    default:
+      return out << "Unknown HpackDecoderStringBuffer::Backing!";
+  }
+}
+
+HpackDecoderStringBuffer::HpackDecoderStringBuffer() {
+  Reset();
+}
+HpackDecoderStringBuffer::~HpackDecoderStringBuffer() {}
+
+// TODO(jamessynge): Consider eliminating most of Reset (i.e. do less); in
+// particular, if a variable won't be read again until after it is next set
+// (e.g. is_huffman_encoded_ or remaining_len_), then it doesn't need to be
+// cleared here. This will be easier when not supporting both HpackDecoder2
+// (in net/spdy/hpack) and HpackWholeEntryDecoder, so we can eliminate
+// the Set() and str() methods.
+void HpackDecoderStringBuffer::Reset() {
+  DVLOG(3) << "HpackDecoderStringBuffer::Reset";
+  buffer_.clear();
+  value_.clear();
+  remaining_len_ = 0;
+  is_huffman_encoded_ = false;
+  state_ = State::RESET;
+  backing_ = Backing::RESET;
+}
+
+void HpackDecoderStringBuffer::Set(StringPiece value, bool is_static) {
+  DVLOG(2) << "HpackDecoderStringBuffer::Set";
+  DCHECK_EQ(state_, State::RESET);
+  DCHECK_EQ(backing_, Backing::RESET);
+  value_ = value;
+  state_ = State::COMPLETE;
+  backing_ = is_static ? Backing::STATIC : Backing::UNBUFFERED;
+}
+
+void HpackDecoderStringBuffer::OnStart(bool huffman_encoded, size_t len) {
+  DVLOG(2) << "HpackDecoderStringBuffer::OnStart";
+  DCHECK_EQ(state_, State::RESET);
+  DCHECK_EQ(backing_, Backing::RESET);
+  buffer_.clear();
+  value_.clear();
+
+  remaining_len_ = len;
+  is_huffman_encoded_ = huffman_encoded;
+
+  state_ = State::COLLECTING;
+
+  if (huffman_encoded) {
+    decoder_.Reset();
+    backing_ = Backing::BUFFERED;
+
+    // Reserve space in buffer_ for the uncompressed string, assuming the
+    // maximum expansion. The shortest Huffman codes in the RFC are 5 bits long,
+    // which then expand to 8 bits during decoding (i.e. each code is for one
+    // plain text octet, aka byte), so the maximum size is 60% longer than the
+    // encoded size.
+    len = len * 8 / 5;
+    if (buffer_.capacity() < len) {
+      buffer_.reserve(len);
+    }
+  } else {
+    // Assume for now that we won't need to use buffer_, so don't reserve space
+    // in it.
+    backing_ = Backing::RESET;
+  }
+}
+
+bool HpackDecoderStringBuffer::OnData(const char* data, size_t len) {
+  DVLOG(2) << "HpackDecoderStringBuffer::OnData state=" << state_
+           << ", backing=" << backing_;
+  DCHECK_EQ(state_, State::COLLECTING);
+  DCHECK_LE(len, remaining_len_);
+  remaining_len_ -= len;
+
+  if (is_huffman_encoded_) {
+    DCHECK_EQ(backing_, Backing::BUFFERED);
+    // We don't set value_ for buffered strings until OnEnd,
+    // so it should be empty.
+    DCHECK_EQ(0u, value_.size());
+    return decoder_.Decode(StringPiece(data, len), &buffer_);
+  }
+
+  if (backing_ == Backing::RESET) {
+    // This is the first call to OnData.
+    DCHECK_EQ(0u, buffer_.size());
+    DCHECK_EQ(0u, value_.size());
+    // If data contains the entire string, don't copy the string. If we later
+    // find that the HPACK entry is split across input buffers, then we'll
+    // copy the string into buffer_.
+    if (remaining_len_ == 0) {
+      value_ = StringPiece(data, len);
+      backing_ = Backing::UNBUFFERED;
+      return true;
+    }
+
+    // We need to buffer the string because it is split across input buffers.
+    backing_ = Backing::BUFFERED;
+    buffer_.assign(data, len);
+    return true;
+  }
+
+  // This is not the first call to OnData for this string, so it should be
+  // buffered.
+  DCHECK_EQ(backing_, Backing::BUFFERED);
+  // We don't set value_ for buffered strings until OnEnd, so it should be
+  // empty.
+  DCHECK_EQ(0u, value_.size());
+
+  // Append to the current contents of the buffer.
+  buffer_.append(data, len);
+  return true;
+}
+
+bool HpackDecoderStringBuffer::OnEnd() {
+  DVLOG(2) << "HpackDecoderStringBuffer::OnEnd";
+  DCHECK_EQ(state_, State::COLLECTING);
+  DCHECK_EQ(0u, remaining_len_);
+
+  if (is_huffman_encoded_) {
+    DCHECK_EQ(backing_, Backing::BUFFERED);
+    // Did the Huffman encoding of the string end properly?
+    if (!decoder_.InputProperlyTerminated()) {
+      return false;  // No, it didn't.
+    }
+  }
+  state_ = State::COMPLETE;
+  if (backing_ == Backing::BUFFERED) {
+    value_ = buffer_;
+  }
+  return true;
+}
+
+void HpackDecoderStringBuffer::BufferStringIfUnbuffered() {
+  DVLOG(3) << "HpackDecoderStringBuffer::BufferStringIfUnbuffered state="
+           << state_ << ", backing=" << backing_;
+  if (state_ != State::RESET && backing_ == Backing::UNBUFFERED) {
+    DVLOG(2) << "HpackDecoderStringBuffer buffering string of length "
+             << value_.size();
+    value_.CopyToString(&buffer_);
+    if (state_ == State::COMPLETE) {
+      value_ = buffer_;
+    }
+    backing_ = Backing::BUFFERED;
+  }
+}
+
+size_t HpackDecoderStringBuffer::BufferedLength() const {
+  DVLOG(3) << "HpackDecoderStringBuffer::BufferedLength";
+  return backing_ == Backing::BUFFERED ? buffer_.size() : 0;
+}
+
+StringPiece HpackDecoderStringBuffer::str() const {
+  DVLOG(3) << "HpackDecoderStringBuffer::str";
+  DCHECK_EQ(state_, State::COMPLETE);
+  return value_;
+}
+
+void HpackDecoderStringBuffer::OutputDebugStringTo(std::ostream& out) const {
+  out << "{state=" << state_;
+  if (state_ != State::RESET) {
+    out << ", backing=" << backing_;
+    out << ", remaining_len=" << remaining_len_;
+    out << ", is_huffman_encoded=" << is_huffman_encoded_;
+    if (backing_ == Backing::BUFFERED) {
+      out << ", buffer: " << buffer_;
+    } else {
+      out << ", value: " << value_;
+    }
+  }
+  out << "}";
+}
+
+std::ostream& operator<<(std::ostream& out, const HpackDecoderStringBuffer& v) {
+  v.OutputDebugStringTo(out);
+  return out;
+}
+
+}  // namespace net