#!/bin/bash
# scanPingLocalnet - Scan local net conf, ping whole local net, then run `host`
#  on each ip who answered to ping.
# (C) 2025 Felix Hauri - felix@f-hauri.ch
# This use forks to `ip` and `host` network tools

scanToVars() { 
    local __ip __net __iface __mask __int __tmp_iArry __tmp_string
    read -r __ip __net __iface < <(ip r g 1.1.1.1 |
	sed -ne 's@.*src \([0-9.]\+\) .*@ip a s |\
		sed -ne \o47s_.*\1/\\([0-9]\\+\\) .* _\1 \\1 _p\o47@p' |
	       	sh);
    __mask=$(( ( ~0 ^ ~0<<32 ) ^ ( ~0 ^ ~0<<(32-$__net) ) ))
    __int=${__ip/./<<24|}; __int=${__int/./<<16|}; __int=${__int/./<<8|}
    mapfile -t range < <(seq $((__int & __mask + 1)) \
		$(( ( ( ~0 ^ ~0<<32 ) ^ __mask|__int ) - 1 )))
    local -ai __tmp_iArry=(${range[@]/%/>>24})
    printf -v __tmp_string 'ping -nc1 -W1 %d.%%d.%%%%d.%%%%%%%%d &\n' ${__tmp_iArry[@]}
    local -ai __tmp_iArry=(${range[@]/%/>>16\&255})
    printf -v __tmp_string "$__tmp_string" ${__tmp_iArry[@]}
    local -ai __tmp_iArry=(${range[@]/%/>>8\&255})
    printf -v __tmp_string "$__tmp_string" ${__tmp_iArry[@]}
    local -ai __tmp_iArry=(${range[@]/%/\&255})
    printf -v __tmp_string "$__tmp_string" ${__tmp_iArry[@]}
    sh -c "$__tmp_string" |
	sed -ne 's/^64.*from \([0-9.]\+\):.*$/host \1 \&/p' |
	sh |& 
	sed -ne '
  /^\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)\.in-.*nter \(.*\)\.$/{
		s//'${1:-host}'[\1|\2<<8|\3<<16|\4<<24]="\5"/p }
	/^Host \([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\).in.* found.*/{
		s//'${1:-host}'[\1|\2<<8|\3<<16|\4<<24]="\4.\3.\2.\1"/p
	}'
}
source <(scanToVars presentList)
declare -p presentList
echo ${presentList[@]%.[^1-9]*}