add openwrt-wireguard example

hypd/examples/openwrt-wireguard/closewireguard.sh

@@ -0,0 +1,14 @@
+#!/bin/sh
+
+if [ $# -lt 1 ]; then
+    echo "Usage: $0 <srcip>"
+    exit 1
+fi
+
+# Can't use dots in rule name, so swap for underscores
+rulename="hypd_${1//./_}_wireguard"
+
+# Configure the rule in OpenWRT's uci interface
+uci delete firewall.$rulename
+uci commit firewall
+service firewall restart