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

net/http2/hpack/decoder/hpack_entry_decoder.cc

Index: net/http2/hpack/decoder/hpack_entry_decoder.cc
diff --git a/net/http2/hpack/decoder/hpack_entry_decoder.cc b/net/http2/hpack/decoder/hpack_entry_decoder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..c47ef0cf7134f7ea19807e892755dda4cceb375c
--- /dev/null
+++ b/net/http2/hpack/decoder/hpack_entry_decoder.cc
@@ -0,0 +1,233 @@
+// 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_entry_decoder.h"
+
+#include <stddef.h>
+
+#include "base/logging.h"
+#include "base/macros.h"
+
+namespace net {
+namespace {
+// Converts calls from HpackStringDecoder when decoding a header name into the
+// appropriate HpackEntryDecoderListener::OnName* calls.
+class NameDecoderListener {
+ public:
+  explicit NameDecoderListener(HpackEntryDecoderListener* listener)
+      : listener_(listener) {}
+  bool OnStringStart(bool huffman_encoded, size_t len) {
+    listener_->OnNameStart(huffman_encoded, len);
+    return true;
+  }
+  void OnStringData(const char* data, size_t len) {
+    listener_->OnNameData(data, len);
+  }
+  void OnStringEnd() { listener_->OnNameEnd(); }
+
+ private:
+  HpackEntryDecoderListener* listener_;
+};
+
+// Converts calls from HpackStringDecoder when decoding a header value into
+// the appropriate HpackEntryDecoderListener::OnValue* calls.
+class ValueDecoderListener {
+ public:
+  explicit ValueDecoderListener(HpackEntryDecoderListener* listener)
+      : listener_(listener) {}
+  bool OnStringStart(bool huffman_encoded, size_t len) {
+    listener_->OnValueStart(huffman_encoded, len);
+    return true;
+  }
+  void OnStringData(const char* data, size_t len) {
+    listener_->OnValueData(data, len);
+  }
+  void OnStringEnd() { listener_->OnValueEnd(); }
+
+ private:
+  HpackEntryDecoderListener* listener_;
+};
+}  // namespace
+
+// Only call Resume if the previous call (Start or Resume) returned
+// kDecodeInProgress; Resume is also called from Start when it has succeeded
+// in decoding the entry type and its varint.
+DecodeStatus HpackEntryDecoder::Resume(DecodeBuffer* db,
+                                       HpackEntryDecoderListener* listener) {
+  DCHECK(db != nullptr);
+  DCHECK(listener != nullptr);
+
+  DecodeStatus status;
+
+  do {
+    switch (state_) {
+      case EntryDecoderState::kResumeDecodingType:
+        // entry_type_decoder_ returned kDecodeInProgress when last called.
+        DVLOG(1) << "kResumeDecodingType: db->Remaining=" << db->Remaining();
+        status = entry_type_decoder_.Resume(db);
+        if (status != DecodeStatus::kDecodeDone) {
+          return status;
+        }
+        state_ = EntryDecoderState::kDecodedType;
+      // FALLTHROUGH_INTENDED
+
+      case EntryDecoderState::kDecodedType:
+        // entry_type_decoder_ returned kDecodeDone, now need to decide how
+        // to proceed.
+        DVLOG(1) << "kDecodedType: db->Remaining=" << db->Remaining();
+        if (DispatchOnType(listener)) {
+          // All done.
+          return DecodeStatus::kDecodeDone;
+        }
+        continue;
+
+      case EntryDecoderState::kStartDecodingName:
+        DVLOG(1) << "kStartDecodingName: db->Remaining=" << db->Remaining();
+        {
+          NameDecoderListener ncb(listener);
+          status = string_decoder_.Start(db, &ncb);
+        }
+        if (status != DecodeStatus::kDecodeDone) {
+          // On the assumption that the status is kDecodeInProgress, set
+          // state_ accordingly; unnecessary if status is kDecodeError, but
+          // that will only happen if the varint encoding the name's length
+          // is too long.
+          state_ = EntryDecoderState::kResumeDecodingName;
+          return status;
+        }
+        state_ = EntryDecoderState::kStartDecodingValue;
+      // FALLTHROUGH_INTENDED
+
+      case EntryDecoderState::kStartDecodingValue:
+        DVLOG(1) << "kStartDecodingValue: db->Remaining=" << db->Remaining();
+        {
+          ValueDecoderListener vcb(listener);
+          status = string_decoder_.Start(db, &vcb);
+        }
+        if (status == DecodeStatus::kDecodeDone) {
+          // Done with decoding the literal value, so we've reached the
+          // end of the header entry.
+          return status;
+        }
+        // On the assumption that the status is kDecodeInProgress, set
+        // state_ accordingly; unnecessary if status is kDecodeError, but
+        // that will only happen if the varint encoding the value's length
+        // is too long.
+        state_ = EntryDecoderState::kResumeDecodingValue;
+        return status;
+
+      case EntryDecoderState::kResumeDecodingName:
+        // The literal name was split across decode buffers.
+        DVLOG(1) << "kResumeDecodingName: db->Remaining=" << db->Remaining();
+        {
+          NameDecoderListener ncb(listener);
+          status = string_decoder_.Resume(db, &ncb);
+        }
+        if (status != DecodeStatus::kDecodeDone) {
+          // On the assumption that the status is kDecodeInProgress, set
+          // state_ accordingly; unnecessary if status is kDecodeError, but
+          // that will only happen if the varint encoding the name's length
+          // is too long.
+          state_ = EntryDecoderState::kResumeDecodingName;
+          return status;
+        }
+        state_ = EntryDecoderState::kStartDecodingValue;
+        break;
+
+      case EntryDecoderState::kResumeDecodingValue:
+        // The literal value was split across decode buffers.
+        DVLOG(1) << "kResumeDecodingValue: db->Remaining=" << db->Remaining();
+        {
+          ValueDecoderListener vcb(listener);
+          status = string_decoder_.Resume(db, &vcb);
+        }
+        if (status == DecodeStatus::kDecodeDone) {
+          // Done with decoding the value, therefore the entry as a whole.
+          return status;
+        }
+        // On the assumption that the status is kDecodeInProgress, set
+        // state_ accordingly; unnecessary if status is kDecodeError, but
+        // that will only happen if the varint encoding the value's length
+        // is too long.
+        state_ = EntryDecoderState::kResumeDecodingValue;
+        return status;
+    }
+  } while (true);
+}
+
+bool HpackEntryDecoder::DispatchOnType(HpackEntryDecoderListener* listener) {
+  const HpackEntryType entry_type = entry_type_decoder_.entry_type();
+  const uint32_t varint = entry_type_decoder_.varint();
+  switch (entry_type) {
+    case HpackEntryType::kIndexedHeader:
+      // The entry consists solely of the entry type and varint. See:
+      // http://httpwg.org/specs/rfc7541.html#indexed.header.representation
+      listener->OnIndexedHeader(varint);
+      return true;
+
+    case HpackEntryType::kIndexedLiteralHeader:
+    case HpackEntryType::kUnindexedLiteralHeader:
+    case HpackEntryType::kNeverIndexedLiteralHeader:
+      // The entry has a literal value, and if the varint is zero also has a
+      // literal name preceding the value. See:
+      // http://httpwg.org/specs/rfc7541.html#literal.header.representation
+      listener->OnStartLiteralHeader(entry_type, varint);
+      if (varint == 0) {
+        state_ = EntryDecoderState::kStartDecodingName;
+      } else {
+        state_ = EntryDecoderState::kStartDecodingValue;
+      }
+      return false;
+
+    case HpackEntryType::kDynamicTableSizeUpdate:
+      // The entry consists solely of the entry type and varint. FWIW, I've
+      // never seen this type of entry in production (primarily browser
+      // traffic) so if you're designing an HPACK successor someday, consider
+      // dropping it or giving it a much longer prefix. See:
+      // http://httpwg.org/specs/rfc7541.html#encoding.context.update
+      listener->OnDynamicTableSizeUpdate(varint);
+      return true;
+  }
+
+  NOTREACHED();
+  return true;
+}
+
+void HpackEntryDecoder::OutputDebugString(std::ostream& out) const {
+  out << "HpackEntryDecoder(state=" << state_ << ", " << entry_type_decoder_
+      << ", " << string_decoder_ << ")";
+}
+
+std::string HpackEntryDecoder::DebugString() const {
+  std::stringstream s;
+  s << *this;
+  return s.str();
+}
+
+std::ostream& operator<<(std::ostream& out, const HpackEntryDecoder& v) {
+  v.OutputDebugString(out);
+  return out;
+}
+
+std::ostream& operator<<(std::ostream& out,
+                         HpackEntryDecoder::EntryDecoderState state) {
+  typedef HpackEntryDecoder::EntryDecoderState EntryDecoderState;
+  switch (state) {
+    case EntryDecoderState::kResumeDecodingType:
+      return out << "kResumeDecodingType";
+    case EntryDecoderState::kDecodedType:
+      return out << "kDecodedType";
+    case EntryDecoderState::kStartDecodingName:
+      return out << "kStartDecodingName";
+    case EntryDecoderState::kResumeDecodingName:
+      return out << "kResumeDecodingName";
+    case EntryDecoderState::kStartDecodingValue:
+      return out << "kStartDecodingValue";
+    case EntryDecoderState::kResumeDecodingValue:
+      return out << "kResumeDecodingValue";
+  }
+  return out << static_cast<int>(state);
+}
+
+}  // namespace net