commit: 75615d58440ce29ed73b6dfc6d7aad358f12d830
parent: 04797a0345407eb4a954dbcf637bd0e7f3a0af2d
author: z0noxz <chris@noxz.tech>
date: Tue, 7 Aug 2018 09:04:34 +0200
only accept valid subnet masks
1 file changed, 41 insertions(+), 5 deletions(-)
diff --git a/ip2cidr b/ip2cidr
@@ -19,31 +19,48 @@ along with this program. If not, see <http://www.gnu.org/licenses/>.
count_ones() {
+ # variable declaration
dec=$1
base=2
result=0
+ found_zero=-1
+ # base convert decimal ip address to binary
while [ "$dec" -ne 0 ]; do
if [ $((dec % base)) -eq 1 ]; then
+ # check if mask is invalid
+ if [ "$found_zero" -eq 1 ]; then
+ printf '%d' "-1"
+ return 1
+ fi
+
+ # count one
result=$((result+1))
+ found_zero=0
+ else
+ # detect zero after a one
+ if [ "$found_zero" -eq 0 ]; then
+ found_zero=1
+ fi
fi
dec=$((dec / base))
done
+ # return value
printf '%d' "$result"
+ return 0
}
do_ip2cidr() {
+ # variable declaration
ip=$1
+ cidr=-1
OIFS=$IFS
result=0
i=0
- if [ "$ip" = "" ]; then
- return 1
- fi
-
+ # parse ip address
IFS=\.
for item in $ip; do
if [ "$item" -eq "$item" ] 2> /dev/null && \
@@ -69,7 +86,24 @@ do_ip2cidr() {
done
IFS=$OIFS
- printf '%d\n' "$(count_ones "$result")"
+ # check if ip address was valid, and if not fail
+ if [ "$ip" = "" ] || [ "$i" -ne 4 ]; then
+ return 1
+ fi
+
+ # calculate CIDR
+ cidr=$(count_ones "$result")
+
+ # check if CIDR is valid, and if not fail
+ if [ "$cidr" -eq -1 ]; then
+ return 1
+ fi
+
+ # print CIDR
+ printf '%d\n' "$cidr"
+
+ # success
+ return 0
}
# check if input already is a CIDR, and if not process it
@@ -84,6 +118,8 @@ fi
program_name="${0##*/}"
printf 'Usage: %s IPADDRESS
+The IPADDRESS must be a valid subnet mask.
+
LICENSE NOTICE
%s
' "$program_name" "$license" >&2
