blob: e7ae9f65c74fa7e2eba325578cdb703e8ef1211c (
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#!/bin/bash
UNIT=socat-dns
verify_service_availability()
{
dig . @127.0.0.1 >/dev/null 2>&1
}
watchdog()
{
PID=$1
enable -f /usr/lib/bash/sleep sleep || true
while verify_service_availability
do
systemd-notify --pid="$PID" WATCHDOG=1
sleep $((${WATCHDOG_USEC:-2000000} / 2000000))
done
}
main()
{
case "$1" in
install)
shift
DEST=${1:-149.56.44.185}
PORT=${2:-53}
LOCAL_PORT=${3:-$PORT}
COMMAND="socat UDP-RECVFROM:$LOCAL_PORT,fork UDP-SENDTO:$DEST:$PORT"
if systemctl is-active "$UNIT" >/dev/null
then
systemctl stop "$UNIT"
fi
systemctl reset-failed "$UNIT" 2>/dev/null
systemd-run \
--unit "$UNIT" \
--property Restart="always" \
--property WatchdogSec="5" \
-- \
"$0" watchdog "$COMMAND"
;;
watchdog)
shift
COMMAND="$1"
watchdog $$ &
exec $COMMAND
;;
*)
echo "Usage: $0 install [destination [destination port [local port]]]" >&2
exit 1
;;
esac
}
main "$@"
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