#!/bin/bash
# manyPing.sh - How to collect many ping's outputs into bash variables
# (C) 2025 Felix Hauri - felix@f-hauri.ch
# Licensed under terms of GPL v3. www.gnu.org
# This script is intented to be used under GNU/Linux, as they use kernel
#   pseudo filesystem /proc (for retrieving mac address, in `getArps` function).
# Collecting networks IPv4 status and infos from parallelized ping's answer,
#   into 5 differents bash arrays:
#  - $byIp      Indexed array: ([167904045]='hosta' [167904046]='hostb'...
#  - $allIPS    Indexed array: ([167904045]='10.2.3.45' [167904046]='10.2.3.46'
#  - $state     Indexed array: ([167904045]='1' [167904046]='0'...
#  - $allUp     Indexed array: ([167904045]='hosta' ...)
#  - $allDown   Indexed array: ([167904046]='hostb' ...)
# Note: In order to avoid bash loops, all array operation are done by "mapping"
#   ( While keeping in mind `declare -a "array=($str)"` is like an `eval`!! )
# In a second operation, another variable from:  mapfile </proc/net/arp, to
#  - $listArps  Indexed array: ([167904045]="01:23:45:67:89:ab" [167904046]=...
#
# All this will by done quickly as there are very limited number of forks
# and bash loops. Tried with 1016 arguments in less than 2sec!
#   manyPing 192.168.{0..3}.{1..254}
#
# Usage: manyPing [-d] <ip or hostname> [ip or hostname] [ip or hostname]...
#      -d  Show sed generated bash, temp string for $listArps and all 6 arrays.
#    Try maybe this:$  manyPing $(awk '/^[1.9]/{if($3)print $3}' </etc/hosts)
#    or:$   manyPing -d  $(awk '/^[1.9]/{if($3)print $3}' </etc/hosts)

if [[ $1 == -d ]]; then  debug=true;  shift;  else  debug=false;  fi

out2var() { # Filter ping output Prepare: byIp, allIPs, state, allDown and allUp
    local sedScr
    mapfile -t sedScr <<-EOSed
	  /PING \(.*\) (\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)) .*/{
	     s//byIp[\2<<24|\3<<16|\4<<8|\5]="\1"
		\nallDown[\2<<24|\3<<16|\4<<8|\5]="\1"
		\nallIPs[\2<<24|\3<<16|\4<<8|\5]="\2.\3.\4.\5"
		\nstate[\2<<24|\3<<16|\4<<8|\5]=0\n/p };
	  /^64.*(\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)):.*/{
	     s//state[\1<<24|\2<<16|\3<<8|\4]=1
		\nunset "allDown[\1<<24|\2<<16|\3<<8|\4]"
		\nallUp[\1<<24|\2<<16|\3<<8|\4]="\${byIp[
			\1<<24|\2<<16|\3<<8|\4]}"\n/p };
	  /^64 .*from \([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)\.\([0-9]\+\)[^)]*$/{
	     s//state[\1<<24|\2<<16|\3<<8|\4]=1
		\nunset "allDown[\1<<24|\2<<16|\3<<8|\4]"
		\nallUp[\1<<24|\2<<16|\3<<8|\4]="\${byIp[
			\1<<24|\2<<16|\3<<8|\4]}"\n/p }
	EOSed
    if $debug; then
	sed -nue "${sedScr[*]}" | tee /dev/stderr
    else
	sed -nue "${sedScr[*]}"
    fi
}
dumpArray() { # Dump array, one field by line
    local _fmt_str _arg;
    for _arg; do
	local -n _array=$_arg
	printf -v _fmt_str ' [%q]=%%s\n' "${!_array[@]}"
	printf "%s=\42(${_fmt_str%$'\n'} )\42\n" $_arg "${_array[@]@Q}"
    done
}
getArps() { # read /proc/net/arp into an ip2int indexed array: listArps
    local __arp_List __arp_CleanedList __tmp_str __ip_list __int_ip
    mapfile -t __arp_List </proc/net/arp
    __arp_List=("${__arp_List[@]:1}")   # Drop header line
    __arp_CleanedList=("${__arp_List[@]//*00:00:00:00:00:00*}") # Drop null
    __arp_List=("${__arp_CleanedList[@]##*0x[0-9] }")           # lines
    read -ra __int_ip <<<"${__arp_CleanedList[*]/ *}" # Create array with all IP
    __int_ip=("${__int_ip[@]/./<<24|}") # Shift 1st value by 24 bits "OR",
    __int_ip=("${__int_ip[@]/./<<16|}") # 2nd value shifted by 16 bits OR 3rd
    __int_ip=("${__int_ip[@]/./<<8|}")  # value shidted by 8 bits OR last value.
    printf -v __tmp_str '[%s]="%%s" ' "${__int_ip[@]}"  # Prepare integer
    read -ra __arp_List <<<"${__arp_List[@]% [*] *}"    # indexed array with all
    printf -v __tmp_str "$__tmp_str" "${__arp_List[@]}" # mac address
    $debug && declare -p __tmp_str
    declare -ga "listArps=($__tmp_str)"  # declare listArps (convert ip to int)
}
printOut() { # Pretty print host, ip, state, mac address with colours.
    local _msg=(Down Up) __idxs=(${!byIp[@]}) _ansiM=( "${state[@]/0/2}" ) _fStr
    local -a __state="(${state[*]/*/\${_msg[&]\}})"
    local -a __hw_mac="(${__idxs[*]/*/\"\$\{listArps[&]\}\"})"
    _fStr='\e[%%%%%%%%%%%%%%%%sm%-24s %%-17s%%%%%%%%-19s%%%%s\e[0m\n'
    printf -v _fStr "$_fStr"    Name            "${byIp[@]}"
    printf -v _fStr "$_fStr"    IP\ Address     "${allIPs[@]}"
    printf -v _fStr "$_fStr"    State           "${__state[@]}"
    printf -v _fStr "$_fStr"    'Mac Address'   "${__hw_mac[@]}"
    printf "$_fStr"             4\;1            "${_ansiM[@]/1/0}"
}

if ! (( $# )); then
    echo >&2 "Arguments missing!"
    sed -ne "/^# Usage/,+2{s|manyPing|$0|;s/^# //;p}" "$0" >&2
    exit 1
fi

started=$EPOCHREALTIME

declare -a byIp=() state=() allIPs=() listArps=() allUp=() allDown=()

source <( # run parallels ping and execute bash directives generated by sed
    for target; do
	ping -n4c1 -W1 $target &
    done |
	out2var
)

getArps

printOut

$debug && dumpArray listArps byIp state all{IPs,Down,Up} >&2

ended=$EPOCHREALTIME  elap=00000$(( ${ended/.} - ${started/.} ))
printf '%d hosts processed in %.3f secs.\n' ${#byIp[@]}  ${elap::-6}.${elap: -6}