improve factoring and add makefile

2 files changed, 42 insertions, 10 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..09918b8
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,6 @@
+
+all:
+
+status install:
+        ./socat.sh $@
+
diff --git a/socat.sh b/socat.sh
index e7ae9f6..1afb4a4 100755
--- a/socat.sh
+++ b/socat.sh
@@ -1,4 +1,5 @@
 #!/bin/bash
+
 UNIT=socat-dns
 
 verify_service_availability()
@@ -6,15 +7,40 @@ verify_service_availability()
     dig . @127.0.0.1 >/dev/null 2>&1
 }
 
+service_launch_command()
+{
+    local dest port local_port
+    dest=${1:-149.56.44.185}
+    case "$dest" in
+        '') return 1 ;;
+        *:*)
+            port=${dest#*:}
+            dest=${dest%%:*}
+        ;;
+        *)
+            port=${2:-53}
+        ;;
+    esac
+    local_port=${3:-$port}
+
+    printf "socat UDP-RECVFROM:%s,fork UDP-SENDTO:%s\n" "$local_port" "$dest:$port"
+}
+
+####
+
 watchdog()
 {
     PID=$1
+    VERIFY=$2
+
+    TWO_MILLION=2000000
+    SLEEP_TIME=$(( ${WATCHDOG_USEC:-$TWO_MILLION} / $TWO_MILLION ))
 
     enable -f /usr/lib/bash/sleep sleep || true
-    while verify_service_availability
+    while $VERIFY
     do
         systemd-notify --pid="$PID" WATCHDOG=1
-        sleep $((${WATCHDOG_USEC:-2000000} / 2000000))
+        sleep "$SLEEP_TIME"
     done
 }
 
@@ -23,10 +49,7 @@ 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"
+            COMMAND=$(service_launch_command "$@")
             if systemctl is-active "$UNIT" >/dev/null
             then
                 systemctl stop "$UNIT"
@@ -38,16 +61,19 @@ main()
                 --property Restart="always" \
                 --property WatchdogSec="5" \
                 -- \
-                "$0" watchdog "$COMMAND"
+                "$0" watchdog "$COMMAND" verify_service_availability
             ;;
         watchdog)
             shift
-            COMMAND="$1"
-            watchdog $$ &
-            exec $COMMAND
+            watchdog $$ "$2" &
+            exec $1
             ;;
+        status)
+            systemctl status "$UNIT"
+            ;;
         *)
             echo "Usage: $0 install [destination [destination port [local port]]]" >&2
+            echo "       $0 status" >&2
             exit 1
             ;;
     esac