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

net/http2/decoder/payload_decoders/ping_payload_decoder.cc

Index: net/http2/decoder/payload_decoders/ping_payload_decoder.cc
diff --git a/net/http2/decoder/payload_decoders/ping_payload_decoder.cc b/net/http2/decoder/payload_decoders/ping_payload_decoder.cc
new file mode 100644
index 0000000000000000000000000000000000000000..abe43d0a6a2d633afdaabd0523ee3b1f80e30202
--- /dev/null
+++ b/net/http2/decoder/payload_decoders/ping_payload_decoder.cc
@@ -0,0 +1,89 @@
+// 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/decoder/payload_decoders/ping_payload_decoder.h"
+
+#include "base/logging.h"
+#include "net/http2/decoder/http2_frame_decoder_listener.h"
+#include "net/http2/http2_constants.h"
+
+namespace net {
+namespace {
+constexpr auto kOpaqueSize = Http2PingFields::EncodedSize();
+}
+
+DecodeStatus PingPayloadDecoder::StartDecodingPayload(FrameDecoderState* state,
+                                                      DecodeBuffer* db) {
+  const Http2FrameHeader& frame_header = state->frame_header();
+  const uint32_t total_length = frame_header.payload_length;
+
+  DVLOG(2) << "PingPayloadDecoder::StartDecodingPayload: " << frame_header;
+  DCHECK_EQ(Http2FrameType::PING, frame_header.type);
+  DCHECK_LE(db->Remaining(), total_length);
+  DCHECK_EQ(0, frame_header.flags & ~(Http2FrameFlag::FLAG_ACK));
+
+  // Is the payload entirely in the decode buffer and is it the correct size?
+  // Given the size of the header and payload (17 bytes total), this is most
+  // likely the case the vast majority of the time.
+  if (db->Remaining() == kOpaqueSize && total_length == kOpaqueSize) {
+    // Special case this situation as it allows us to avoid any copying;
+    // the other path makes two copies, first into the buffer in
+    // Http2StructureDecoder as it accumulates the 8 bytes of opaque data,
+    // and a second copy into the Http2PingFields member of in this class.
+    // This supports the claim that this decoder is (mostly) non-buffering.
+    static_assert(sizeof(Http2PingFields) == kOpaqueSize,
+                  "If not, then can't enter this block!");
+    auto ping = reinterpret_cast<const Http2PingFields*>(db->cursor());
+    if (frame_header.IsAck()) {
+      state->listener()->OnPingAck(frame_header, *ping);
+    } else {
+      state->listener()->OnPing(frame_header, *ping);
+    }
+    db->AdvanceCursor(kOpaqueSize);
+    return DecodeStatus::kDecodeDone;
+  }
+  state->InitializeRemainders();
+  return HandleStatus(
+      state, state->StartDecodingStructureInPayload(&ping_fields_, db));
+}
+
+DecodeStatus PingPayloadDecoder::ResumeDecodingPayload(FrameDecoderState* state,
+                                                       DecodeBuffer* db) {
+  DVLOG(2) << "ResumeDecodingPayload: remaining_payload="
+           << state->remaining_payload();
+  DCHECK_EQ(Http2FrameType::PING, state->frame_header().type);
+  DCHECK_LE(db->Remaining(), state->frame_header().payload_length);
+  return HandleStatus(
+      state, state->ResumeDecodingStructureInPayload(&ping_fields_, db));
+}
+
+DecodeStatus PingPayloadDecoder::HandleStatus(FrameDecoderState* state,
+                                              DecodeStatus status) {
+  DVLOG(2) << "HandleStatus: status=" << status
+           << "; remaining_payload=" << state->remaining_payload();
+  if (status == DecodeStatus::kDecodeDone) {
+    if (state->remaining_payload() == 0) {
+      const Http2FrameHeader& frame_header = state->frame_header();
+      if (frame_header.IsAck()) {
+        state->listener()->OnPingAck(frame_header, ping_fields_);
+      } else {
+        state->listener()->OnPing(frame_header, ping_fields_);
+      }
+      return DecodeStatus::kDecodeDone;
+    }
+    // Payload is too long.
+    return state->ReportFrameSizeError();
+  }
+  // Not done decoding the structure. Either we've got more payload to decode,
+  // or we've run out because the payload is too short.
+  DCHECK(
+      (status == DecodeStatus::kDecodeInProgress &&
+       state->remaining_payload() > 0) ||
+      (status == DecodeStatus::kDecodeError && state->remaining_payload() == 0))
+      << "\n status=" << status
+      << "; remaining_payload=" << state->remaining_payload();
+  return status;
+}
+
+}  // namespace net