fix BEASTHOST ip resolution bug

rootfs/etc/s6-overlay/scripts/radar1090

@@ -53,13 +53,13 @@ fi
 
 beast_host="${BEASTHOST:-ultrafeeder}"
 if ! valid_ip "$beast_host"; then
-	beast_host="$(dig "$beast_host" | awk '{if ($1 == "'"$beast_host"'.") print $5}')"
+	beast_host="$(dig "${BEASTHOST:-ultrafeeder}" | awk '{if ($1 == "'"${BEASTHOST:-ultrafeeder}"'.") print $5}')"
     # If it fails, print error message and loop trying every 30 secs
-	if [[ -z "$beast_host" ]]; then
-        while [[ -z "$beast_host" ]]; do
+	if ! valid_ip "$beast_host"; then
+        while ! valid_ip "$beast_host"; do
             "${s6wrap[@]}" --args echo "WARNING: BEASTHOST (\"${BEASTHOST:-ultrafeeder}\") cannot be resolved. Make sure that \"${BEASTHOST:-ultrafeeder}\" is running or check your BEASTHOST parameter setting. Trying again in 30 seconds."
             sleep 30
-            beast_host="$(dig "$beast_host" | awk '{if ($1 == "'"$beast_host"'.") print $5}')"
+            beast_host="$(dig "$${BEASTHOST:-ultrafeeder}" | awk '{if ($1 == "'"${BEASTHOST:-ultrafeeder}"'.") print $5}')"
         done
     fi
     chk_enabled "$VERBOSE" && "${s6wrap[@]}" --args echo "BEASTHOST (\"${BEASTHOST:-ultrafeeder}\") successfully resolved to $beast_host" || true