Difference between revisions of "Pro cidr2mask and mask2cidr scripts"
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| − | taken from http://forums.gentoo.org/viewtopic-p-6770850.html | + | taken from http://forums.gentoo.org/viewtopic-p-6770850.html |
| − | function cidr2netmask() | + | |
| − | { | + | == plugable bash functions== |
| + | |||
| + | # Function takes two arguments, 1st arg= netmask variable, 2nd arg = return variable name | ||
| + | # i.e. | ||
| + | # netmask2cidr $MASK CIDR<br> | ||
| + | netmask2cidr() | ||
| + | { | ||
| + | local returnval=$2 | ||
| + | # Phase 1: Count how many 255 prefixes | ||
| + | local mask="${1//255./xrandomx}" sfx=${1//255.} | ||
| + | mask="${mask%%[[:digit:]]*}" | ||
| + | set -- ${#mask} ${sfx//./ } | ||
| + | <br> # Phase 2: Convert the first non-255 number, rest is supposed to be zeroes | ||
| + | mask="0--.128.192.224.240.248.252.254." | ||
| + | mask="${mask//$2*}" | ||
| + | local result=`echo $(( ${1} + ${#mask}/4 ))` | ||
| + | eval $returnval="'$result'" | ||
| + | } | ||
| + | |||
| + | similar to above, but opposite conversion | ||
| + | # function to perform cidr to dot netmask conversion | ||
| + | cidr2netmask() | ||
| + | { | ||
| + | local returnval=$2 | ||
local maskpat="255 255 255 255" | local maskpat="255 255 255 255" | ||
local maskdgt="254 252 248 240 224 192 128" | local maskdgt="254 252 248 240 224 192 128" | ||
set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3} | set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3} | ||
| − | echo ${1-0}.${2-0}.${3-0}.${4-0} | + | local result=`echo ${1-0}.${2-0}.${3-0}.${4-0}` |
| − | + | eval $returnval="'$result'" | |
| − | + | } | |
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Here's the complete script to test these two functions and examples: | Here's the complete script to test these two functions and examples: | ||
cidrnetmask.sh: | cidrnetmask.sh: | ||
| − | #!/bin/sh | + | #!/bin/sh |
| − | # Script: cidrnetmask.sh | + | # Script: cidrnetmask.sh |
| − | # By Vince C <v_cadet AT yahoo.fr>. | + | # By Vince C <v_cadet AT yahoo.fr>. |
| − | # Released under the WTFPL :D . | + | # Released under the WTFPL :D . |
| − | + | function is_number() | |
| − | function is_number() | + | { |
| − | { | + | |
[ -n "${1}" ] && [ -z "${1//[[:digit:]]}" ] | [ -n "${1}" ] && [ -z "${1//[[:digit:]]}" ] | ||
| − | } | + | } |
| − | + | function cidr2netmask() | |
| − | function cidr2netmask() | + | { |
| − | { | + | |
local maskpat="255 255 255 255" | local maskpat="255 255 255 255" | ||
local maskdgt="254 252 248 240 224 192 128" | local maskdgt="254 252 248 240 224 192 128" | ||
set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3} | set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3} | ||
echo ${1-0}.${2-0}.${3-0}.${4-0} | echo ${1-0}.${2-0}.${3-0}.${4-0} | ||
| − | } | + | } |
| − | + | ||
function netmask2cidr() | function netmask2cidr() | ||
{ | { | ||
Latest revision as of 14:04, 28 August 2013
taken from http://forums.gentoo.org/viewtopic-p-6770850.html
plugable bash functions
# Function takes two arguments, 1st arg= netmask variable, 2nd arg = return variable name # i.e. # netmask2cidr $MASK CIDR
netmask2cidr() { local returnval=$2 # Phase 1: Count how many 255 prefixes local mask="${1//255./xrandomx}" sfx=${1//255.} mask="${mask%%digit:*}" set -- ${#mask} ${sfx//./ }
# Phase 2: Convert the first non-255 number, rest is supposed to be zeroes mask="0--.128.192.224.240.248.252.254." mask="${mask//$2*}" local result=`echo $(( ${1} + ${#mask}/4 ))` eval $returnval="'$result'" }
similar to above, but opposite conversion
# function to perform cidr to dot netmask conversion
cidr2netmask()
{
local returnval=$2
local maskpat="255 255 255 255"
local maskdgt="254 252 248 240 224 192 128"
set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3}
local result=`echo ${1-0}.${2-0}.${3-0}.${4-0}`
eval $returnval="'$result'"
}
Here's the complete script to test these two functions and examples:
cidrnetmask.sh:
#!/bin/sh
# Script: cidrnetmask.sh
# By Vince C <v_cadet AT yahoo.fr>.
# Released under the WTFPL :D .
function is_number()
{
[ -n "${1}" ] && [ -z "${1//digit:}" ]
}
function cidr2netmask()
{
local maskpat="255 255 255 255"
local maskdgt="254 252 248 240 224 192 128"
set -- ${maskpat:0:$(( ($1 / 8) * 4 ))}${maskdgt:$(( (7 - ($1 % 8)) * 4 )):3}
echo ${1-0}.${2-0}.${3-0}.${4-0}
}
function netmask2cidr()
{
# Phase 1: Count how many 255 prefixes
local mask="${1//255./xrandomx}" sfx=${1//255.}
mask="${mask%%digit:*}"
set -- ${#mask} ${sfx//./ }
# Phase 2: Convert the first non-255 number, rest is supposed to be zeroes
mask="0--.128.192.224.240.248.252.254."
mask="${mask//$2*}"
echo $(( ${1} + ${#mask}/4 ))
}
# Parse and validate arguments
[ -z "$1" ] && exit 0
[ "${1%/*}" == "$1" ] && mask="$2" || mask="${1#*/}"
[ -z "$mask" ] && echo "No netmask." && exit 0
# Check and convert mask
ip=${1%/*}
# Convert CIDR to netmask and vice versa
echo -n "IP: ${ip}/${mask} --> ${ip}/"
is_number $mask && cidr2netmask $mask || netmask2cidr $mask
