initial

1 files changed, 57 insertions, 0 deletions

diff --git a/socat.sh b/socat.sh
new file mode 100755
index 0000000..9d41445
--- /dev/null
+++ b/socat.sh
@@ -0,0 +1,57 @@
+#!/bin/bash
+UNIT=socat-dns
+
+DEST=${1:-149.56.44.185}
+PORT=${2:-53}
+LOCAL_PORT=${3:-$PORT}
+
+COMMAND="socat -v UDP-RECVFROM:$LOCAL_PORT,fork UDP-SENDTO:$DEST:$PORT"
+
+verify_service_availability()
+{
+    true
+    return
+    dig . @localhost
+}
+
+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 "$1" in
+        install)
+            if systemctl is-active "$UNIT" >/dev/null
+            then
+                systemctl stop "$UNIT"
+            fi
+            systemctl reset-failed "$UNIT" 2>/dev/null
+
+            systemd-run \
+                --unit "$UNIT" \
+                --property Restart="on-failure" \
+                --property WatchdogSec="5" \
+                -- \
+                "$0" watchdog
+            ;;
+        watchdog)
+            watchdog $$ &
+            exec $COMMAND
+            ;;
+        *)
+            echo "Usage: $0 <watchdog|install>" >&2
+            exit 1
+            ;;
+    esac
+}
+
+main "$@"