37 lines
929 B
Bash
37 lines
929 B
Bash
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#!/bin/bash
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# expects mask prefix length and the digit
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function _mask_ip_digit() {
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if [[ $1 -ge 8 ]]; then
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MASK=255
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else
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if [[ $1 -le 0 ]]; then
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MASK=0
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else
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VALUES=('0' '128' '192' '224' '240' '248' '252' '254' '255')
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MASK=${VALUES[$1]}
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fi
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fi
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echo $(( $2 & $MASK ))
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}
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# transforms a specific ip with CIDR suffix like 1.2.3.4/16
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# to subnet with cidr suffix like 1.2.0.0/16
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function _sanitize_ipv4_to_subnet_cidr() {
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IP=${1%%/*}
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PREFIX_LENGTH=${1#*/}
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# split IP by . into digits
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DIGITS=(${IP//./ })
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# mask digits according to prefix length
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MASKED_DIGITS=()
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DIGIT_PREFIX_LENGTH="$PREFIX_LENGTH"
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for DIGIT in "${DIGITS[@]}" ; do
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MASKED_DIGITS+=( $(_mask_ip_digit $DIGIT_PREFIX_LENGTH $DIGIT) )
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DIGIT_PREFIX_LENGTH=$(( $DIGIT_PREFIX_LENGTH - 8 ))
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done
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# output masked ip plus prefix length
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echo ${MASKED_DIGITS[0]}.${MASKED_DIGITS[1]}.${MASKED_DIGITS[2]}.${MASKED_DIGITS[3]}/$PREFIX_LENGTH
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}
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