#!/bin/bash
# Finding common network for 2 ipv4 arguments
#
# (C) 2016-2020 Felix Hauri - felix@f-hauri.ch
# Licensed under terms of LGPL v3. www.gnu.org
#
# Usage: $0 xxx.xxx.xxx.xxx yyy.yyy.yyy.yyy (two IPv4 Address)

ip2int() {
    local _a=(${1//./ })
    printf ${2+-v} $2 "%u" $((_a<<24 |${_a[1]}<< 16|${_a[2]}<< 8|${_a[3]}))
}
int2ip() {
    printf ${2+-v} $2 "%d.%d.%d.%d" \
	$(($1>>24)) $(($1>>16&255)) $(($1>>8&255)) $(($1&255))
}
mask2int() {
    printf ${2+-v} $2 "%u" $(( ( ~0 ^ ~0<<32 ) ^ ( ~0 ^ ~0<<(32-$1) ) ))
}
shopt -s extglob
int2bin () { 
    local _fmt="" _i _p
    printf -v _fmt "_out=\${_out//%s/%%03o};" {0..7}
    printf -v _fmt "$_fmt\n" 0 1 8 9 64 65 72 73
    eval "${FUNCNAME}()"'{ local _out;printf -v _out "%o" $1;'${_fmt}'
	printf -v _out "%32s" ${_out##*(0)}; _out=${_out// /0};
	printf -v _out "%s %s %s %s" \
		${_out:0:8} ${_out:8:8} ${_out:16:8} ${_out:24:8};
	_p=$(($2+($2>8)+($2>16)+($2>24))) &&
		printf -v _out "%s.%s" "${_out:0:_p}" "${_out:_p}";
	printf -v $3 "%s" "$_out";}'
    $FUNCNAME $@
}

ip2int $1 ip1
ip2int $2 ip2

for((i=0;i<32;i++)){
    (( ((ip1>>(31-i))&1) == ((ip2>>(31-i))&1) )) || break
}

lmask=$i
mask2int $lmask	mask

((ip1>ip2))&&{ ipC=$ip1;ip1=$ip2;ip2=$ipC; }

inetbase=$((ip1&mask))
ibrdcast=$(((mask ^  ( ~0 ^ ~0<<32 )) | ip1 ))
cnt=$((ibrdcast-inetbase-1))
int2ip	$inetbase	netbase
int2ip	$mask		netmask
int2ip	$((inetbase|1))	first
int2ip	$((ibrdcast-1))	last
int2ip	$ibrdcast	broadcast
int2ip	$ip1		sub1
int2ip	$ip2		sub2

int2bin	$inetbase	$lmask	bnetbase
int2bin	$mask		$lmask	bnetmask
int2bin	$((inetbase|1))	$lmask	bfirst
int2bin	$((ibrdcast-1))	$lmask	blast
int2bin	$ibrdcast	$lmask	bbroadcast
int2bin	$ip1		$lmask	bsub1
int2bin	$ip2		$lmask	bsub2

printf "  %-23s: %-32s %s\n" \
   Network	"$netbase/$lmask ($cnt hosts)" "$bnetbase" \
   Netmask	$netmask "$bnetmask" \
   Broadcast	$broadcast "$bbroadcast" \
   First\ host	$first "$bfirst" \
   "ArgMin (hst $((ip1-inetbase)))"	$sub1 "$bsub1" \
   "ArgMax (hst $((ip2-inetbase)))"	$sub2 "$bsub2" \
   Last\ host	$last "$blast"