#!/bin/bash
# rand.sh - functions for generating public IP addresses

function random_ip() {
	# basing on https://en.wikipedia.org/wiki/Reserved_IP_addresses
	
	first=$(echo "$(shuf -i 128-223 -n1; shuf -i 11-126 -n1; shuf -i 1-9 -n1)" | shuf | tail -n1)

	if [[ $first == 100 ]]; then
		second=$(echo "$(shuf -i 0-63 -n1; shuf -i 128-254 -n1)" | shuf | tail -n1)
		_rest

	elif [[ $first == 169 ]]; then
		second=$(shuf -i 0-253 -n1)
		_rest

	elif [[ $first == 172 ]]; then
		second=$(echo "$(shuf -i 0-15 -n1; shuf -i 32-254 -n1)" | shuf | tail -n1)
		_rest

	elif [[ $first == 192 ]]; then
		second=$(echo "$(shuf -i 0-167 -n1; shuf -i 169-254 -n1)" | shuf | tail -n1)
		if [[ $second == 88 ]]; then
			third=$(echo "$(shuf -i 0-98 -n1; shuf -i 100-254 -n1)" | shuf | tail -n1)
		else
			third=$(shuf -i 1-254 -n1)
		fi
		fourth=$(shuf -i 1-254 -n1)

	elif [[ $first == 198 ]]; then
		second=$(echo "$(shuf -i 0-17 -n1; shuf -i 20-254 -n1)" | shuf | tail -n1)
		if [[ $second == 51 ]]; then
			third=$(echo "$(shuf -i 0-99 -n1; shuf -i 101-254 -n1)" | shuf | tail -n1)
		else
			third=$(shuf -i 1-254 -n1)			
		fi
		fourth=$(shuf -i 1-254 -n1)

	elif [[ $first == 203 ]]; then
		second=$(shuf -i 0-254 -n1)
		if [[ $second == 0 ]]; then
			third=$(echo "$(shuf -i 0-112 -n1; shuf -i 114-254 -n1)" | shuf | tail -n1)
		else
			third=$(shuf -i 1-254 -n1)
		fi
		fourth=$(shuf -i 1-254 -n1)

	else
		second=$(shuf -i 0-254 -n1)
		_rest

	fi

	echo "$first.$second.$third.$fourth"
}

function _rest() {
	third=$(shuf -i 0-254 -n1)
	fourth=$(shuf -i 1-254 -n1)
}