ipvalid.go

package main

import (
	"errors"
	"fmt"
	"net"
	"regexp"
	"strings"
)

func main() {
	isPrivate, _ := PrivateIP("192.168.1.6")
	isIPv4 := ValidIP4("185.123.045.223")
	fmt.Println(isPrivate)
	fmt.Println(isIPv4)
}

func PrivateIP(ip string) (bool, error) {
	var err error
	private := false
	IP := net.ParseIP(ip)
	if IP == nil {
		err = errors.New("Invalid IP")
	} else {
		_, private24BitBlock, _ := net.ParseCIDR("10.0.0.0/8")
		_, private20BitBlock, _ := net.ParseCIDR("172.16.0.0/12")
		_, private16BitBlock, _ := net.ParseCIDR("192.168.0.0/16")
		private = private24BitBlock.Contains(IP) || private20BitBlock.Contains(IP) || private16BitBlock.Contains(IP)
	}
	return private, err
}

func ValidIP4(ipAddress string) bool {
	ipAddress = strings.Trim(ipAddress, " ")
	re, _ := regexp.Compile(`^(([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])\.){3}([0-9]|[1-9][0-9]|1[0-9]{2}|2[0-4][0-9]|25[0-5])$`)
	if re.MatchString(ipAddress) {
		return true
	}
	return false
}