tapsetup: add --loss option

dist/tools/tapsetup/tapsetup

@@ -45,6 +45,8 @@ usage() {
     echo "                                 (ignored on OSX and FreeBSD)" >&2
     echo "   -u, --uplink:                 Optional uplink interface" >&2
     echo "                                 (ignored on OSX and FreeBSD)" >&2
+    echo "   --loss:                       Optional loss %" >&2
+    echo "                                 (ignored on OSX and FreeBSD)" >&2
     echo "   -h, --help:                   Prints this text" >&2
 }
 
@@ -320,6 +322,9 @@ create_iface() {
             if [ -z "${TUNNAME}" ]; then
                 ip link set dev ${NAME}${N} master ${BRNAME} || exit 1
             fi
+            if [ -n "${LOSS}" ]; then
+                tc qdisc add dev ${NAME}${N} root netem loss ${LOSS}
+            fi
             ip link set ${NAME}${N} up || exit 1 ;;
         OSX)
             chown ${SUDO_USER} /dev/${NAME}${N} || exit 1
@@ -476,6 +481,15 @@ while true ; do
                     UPLINK="$2"
                     shift 2 ;;
             esac ;;
+        --loss)
+            case "$2" in
+                "")
+                    usage
+                    exit 2 ;;
+                *)
+                    LOSS="$2"
+                    shift 2 ;;
+            esac ;;
         -t|--tap)
             case "$2" in
                 "")