First release of open-appsec source code

components/security_apps/waap/waap_clib/RateLimiter.h

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+// Copyright (C) 2022 Check Point Software Technologies Ltd. All rights reserved.
+
+// Licensed under the Apache License, Version 2.0 (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 <chrono>
+#include <vector>
+
+namespace Waap {
+namespace Util {
+
+// Simple rate limiter primitive that collects events() and only allows up to X events per Y seconds.
+// For each event, call RateLimiter::event() passing real or simulated timestamp (in seconds).
+// The returned boolean value will tell the caller whether this event must pass (true) or be blocked (false).
+
+class RateLimiter {
+public:
+    RateLimiter(unsigned int events, std::chrono::seconds interval);
+    void clear(const std::chrono::seconds& now);
+    bool event(const std::chrono::seconds& now);
+
+private:
+
+    unsigned m_max_events; // max events allowed during the recent interval window
+    std::chrono::seconds m_interval; // configured interval window
+    std::vector<unsigned> m_hitsPerSecond; // array of hitcounts per second (remembers up to interval recent seconds)
+    unsigned m_recentIdx;  // index of recent second
+    std::chrono::seconds m_recentHitTime; // timestamp of recent second
+    unsigned m_hitsCount; // total events during last interval seconds (rolling update)
+};
+
+}
+}