check_if_port_available.func

#!/bin/bash
#              ###########################################
#              ##########                       ##########
#              ##########        SPLITTER       ##########
#              ##########       Ver: 0.2.4      ##########
#              ##########                       ##########
#              ###########################################
#
#       Created By: Rener Alberto (aka Gr1nch) - DcLabs Security Team
#       E-Mail: rener.silva@protonmail.com
#       PGP Key ID: 0x65f912ed59949f8e
#       PGP Key FingerPrint: 7B7A 8E83 82D3 DACD 4B3B  CFE0 65F9 12ED 5994 9F8E
#       PGP KEY Download: https://pgp.mit.edu/pks/lookup?op=get&search=0x65F912ED59949F8E
#
#       BSD License - Do whatever you want with this script, but take the responsibility!
#       You are responsible for your actions.
#       The creator assume no liability and is not responsible for any misuse or damage.


# This function just check if the selected port is available before
# use it.
check_if_port_available () {
	PORT_FREE=0 # 0(Zero) means that the port is not available and 1 means that this port is available
	REQUESTED_PORT="${1}"
	while [ ${PORT_FREE} -lt 1 ]
	do
		netstat -n | grep ":${REQUESTED_PORT} " 2>&1 > /dev/null
		port_control=$(echo $?)
		if test "${port_control}" != "1" ; then #Check if this port is available
			REQUESTED_PORT="$((REQUESTED_PORT + 1))"
			check_if_port_available "${REQUESTED_PORT}" #call this function again to check if the new port is available
		else
			NEXT_PORT_AVAILABLE="${REQUESTED_PORT}"
			PORT_FREE=1 #The port is available. Exit the loop
		fi
	done
}