selftests: netfilter: add command usage

Avoid bad command arguments.
Based on tools/power/cpupower/bench/cpufreq-bench_plot.sh

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/tools/testing/selftests/netfilter/nft_flowtable.sh b/tools/testing/selftests/netfilter/nft_flowtable.sh
index 44a8798..431296c 100755 (executable)
--- a/tools/testing/selftests/netfilter/nft_flowtable.sh
+++ b/tools/testing/selftests/netfilter/nft_flowtable.sh
@@ -86,12 +86,23 @@ omtu=9000
 lmtu=1500
 rmtu=2000
 
+usage(){
+       echo "nft_flowtable.sh [OPTIONS]"
+       echo
+       echo "MTU options"
+       echo "   -o originator"
+       echo "   -l link"
+       echo "   -r responder"
+       exit 1
+}
+
 while getopts "o:l:r:" o
 do
        case $o in
                o) omtu=$OPTARG;;
                l) lmtu=$OPTARG;;
                r) rmtu=$OPTARG;;
+               *) usage;;
        esac
 done