nemora-postd: import from gBMC

This is the POST code portion of nemorad.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Google-Bug-Id: 179618653
Change-Id: Icf68fe8adf62c646238cf8235918a13effa857f8
diff --git a/subprojects/nemora-postd/src/serializer.hpp b/subprojects/nemora-postd/src/serializer.hpp
new file mode 100644
index 0000000..2dedc85
--- /dev/null
+++ b/subprojects/nemora-postd/src/serializer.hpp
@@ -0,0 +1,38 @@
+// Copyright 2021 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#pragma once
+#include "nemora_types.hpp"
+
+#include <arpa/inet.h>
+
+#include <cstddef>
+#include <cstdint>
+#include <memory>
+#include <string>
+
+using std::int32_t;
+using std::size_t;
+using std::uint64_t;
+
+class Serializer
+{
+  public:
+    static std::string Serialize(const NemoraDatagram* dgram);
+
+  private:
+    static std::string SerializeEvent(const NemoraEvent* event);
+
+    static constexpr uint64_t NEMORA_EVENT_PB_MAGIC = 0x890ebd38ec325800;
+};