Golang : Validate IP address
Problem :
You need to validate if a given IP address string is a valid IP address.
Solution :
Use regexp.Compile
function to validate the string.
For example :
package main
import (
"fmt"
"regexp"
"strings"
)
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
}
// NOTE : ip6 regular expression validation caused runtime error
// runtime error: invalid memory address or nil pointer dereference
//func validIP6(ip6Address string) bool {
// ip6Address = strings.Trim(ip6Address, " ")
// re, _ := regexp.Compile(`([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))`)
// if re.MatchString(ip6Address) {
// return true
// }
// return false
//}
func main() {
ip1 := "192.168.0.0"
vIP1 := validIP4(ip1)
fmt.Printf("%s is a valid IP4 address : %v \n", ip1, vIP1)
//-----------------------------
ip2 := "192.168.a.0"
vIP2 := validIP4(ip2)
fmt.Printf("%s is a valid IP4 address : %v \n", ip2, vIP2)
//-----------------------------
fullIP6 := "FE80:0000:0000:0000:0202:B3FF:FE1E:8329"
vfullIP6 := validIP4(fullIP6)
fmt.Printf("%s is a valid IP4 address : %v \n", fullIP6, vfullIP6)
//-----------------------------
collapsedIP6 := "FE80::0202:B3FF:FE1E:8329"
vcollapsedIP6 := validIP4(collapsedIP6)
fmt.Printf("%s is a valid IP4 address : %v \n", collapsedIP6, vcollapsedIP6)
//-----------------------------
urlIP6 := "http://[2001:db8:0:1]:80"
vurlIP6 := validIP4(urlIP6)
fmt.Printf("%s is a valid IP4 address : %v \n", urlIP6, vurlIP6)
}
Output :
192.168.0.0 is a valid IP4 address : true
192.168.a.0 is a valid IP4 address : false
FE80:0000:0000:0000:0202:B3FF:FE1E:8329 is a valid IP4 address : false
FE80::0202:B3FF:FE1E:8329 is a valid IP4 address : false
http://[2001:db8:0:1]:80 is a valid IP4 address : false
NOTE : I'm not able to get the right regular expression to validate ip6 address yet. If you have a solution, please leave a comment below. :-)
UPDATE : You can also use net.ParseIP()
instead of regular expression to validate a given IP address. Except IP version 6 address with URL or port number.
var ipAddress string = "192.168.0.1"
//sanity check
testInput := net.ParseIP(ipAddress)
if testInput.To4() == nil {
fmt.Printf("%v is not a valid IPv4 address\n", testInput)
}
or
var ip6Address string = "FE80::0202:B3FF:FE1E:8329"
//sanity check
testInputIP6 := net.ParseIP(ip6Address)
if testInputIP6.To16() == nil {
fmt.Printf("%v is not a valid IP address\n", testInputIP6)
}
Reference :
See also : Golang : Validate hostname
By Adam Ng
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