new(userspace/falco): grpc context and stream context

Co-authored-by: Lorenzo Fontana <lo@linux.com>
Signed-off-by: Leonardo Di Donato <leodidonato@gmail.com>

userspace/falco/grpc_context.cpp

@@ -0,0 +1,35 @@
+/*
+Copyright (C) 2016-2019 The Falco Authors
+
+This file is part of falco.
+
+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.
+*/
+
+#include "grpc_context.h"
+
+context::context(grpc::ServerContext* ctx):
+	m_ctx(ctx)
+{
+	// todo: set thread-specific prefix "[session id][request id]"
+}
+
+void context::get_metadata(std::string key, std::string& val)
+{
+	const std::multimap<grpc::string_ref, grpc::string_ref>& client_metadata = m_ctx->client_metadata();
+	auto it = client_metadata.find(key);
+	if(it != client_metadata.end())
+	{
+		val.assign(it->second.data(), it->second.size());
+	}
+}

userspace/falco/grpc_context.h

@@ -0,0 +1,56 @@
+/*
+Copyright (C) 2016-2019 The Falco Authors
+
+This file is part of falco.
+
+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
+
+#ifdef GRPC_INCLUDE_IS_GRPCPP
+#include <grpcpp/grpcpp.h>
+#else
+#include <grpc++/grpc++.h>
+#endif
+
+class context
+{
+public:
+	context(grpc::ServerContext* ctx);
+	~context() = default;
+
+	void get_metadata(std::string key, std::string& val);
+
+private:
+	grpc::ServerContext* m_ctx = nullptr;
+};
+
+class stream_context : public context
+{
+public:
+	stream_context(grpc::ServerContext* ctx): context(ctx) {}
+	~stream_context() = default;
+
+private:
+	enum : char
+	{
+		STREAMING = 1,
+		SUCCESS,
+		ERROR
+	} m_status = STREAMING;
+	// Request-specific stream data
+	mutable void* m_stream = nullptr;
+	// Are there more responses to stream?
+	mutable bool m_has_more = false;
+};