1 files changed, 15 insertions, 1 deletions
diff --git a/cac b/cac
index 3f6e501..c6ab4e4 100755
--- a/cac
+++ b/cac
@@ -45,6 +45,20 @@ sed '
   s/~/%7e/g
 '
 }
+netmask_to_prefix() {(
+#! /bin/sh
+set -euf
+
+netmask=$1
+
+binaryNetmask=$(echo $1 | sed 's/^/obase=2;/;s/\./;/g' | bc | tr -d \\n)
+binaryPrefix=$(echo $binaryNetmask | sed -n 's/^\(1*\)0*$/\1/p')
+if ! echo $binaryPrefix | grep -q .; then
+  echo $0: bad netmask: $netmask >&2
+  exit 4
+fi
+printf %s $binaryPrefix | tr -d 0 | wc -c
+)}
 #
 
 cac_resources_cache=${cac_resources_cache-$HOME/tmp/cac_resources_cache.json}
@@ -196,7 +210,7 @@ __cac_cli__generatenetworking() {(
   gateway=$(echo $server | jq -r .gateway)
   nameserver=8.8.8.8
   netmask=$(echo $server | jq -r .netmask)
-  prefix=$(netmask-to-prefix $netmask)
+  prefix=$(netmask_to_prefix $netmask)
 
   #printf '# Generated file: %s generatenetworking %s %s\n' "$0" "$1" "$2"
   #printf '# on %s\n' "$(date -Is)"