add new example scripts

backend/example_scripts/chaos_delay_jitter.py

@@ -0,0 +1,54 @@
+#!/usr/bin/env python3
+"""Minimal NFQUEUE example: add random delay and jitter, but do not drop packets."""
+
+import random
+import signal
+import sys
+import time
+
+from netfilterqueue import NetfilterQueue
+
+# Demo tuning values.
+BASE_DELAY_MS = 40
+JITTER_MS = 120
+
+nfq = NetfilterQueue()
+
+
+def _handle_packet(packet) -> None:
+    delay_ms = BASE_DELAY_MS + random.uniform(0, JITTER_MS)
+    time.sleep(delay_ms / 1000.0)
+    packet.accept()
+
+
+def _stop(_sig, _frame) -> None:
+    raise SystemExit(0)
+
+
+def main() -> int:
+    if len(sys.argv) != 2:
+        print("Usage: chaos_delay_jitter.py <qnum>", file=sys.stderr)
+        return 1
+
+    try:
+        qnum = int(sys.argv[1])
+    except ValueError:
+        print("qnum must be an integer", file=sys.stderr)
+        return 1
+
+    signal.signal(signal.SIGINT, _stop)
+    signal.signal(signal.SIGTERM, _stop)
+
+    nfq.bind(qnum, _handle_packet)
+    try:
+        nfq.run()
+    except KeyboardInterrupt:
+        pass
+    finally:
+        nfq.unbind()
+
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())