Golang : Validate hostname

Problem :

You need to validate if a given string is a valid hostname or not. Hostnames such as :

 www.socketloop.com

 socketloop.com

 google.com

 digitalocean.com

Solution :

Use regexp.Compile function to validate the string.

For example :

 package main

 import (
 "fmt"
 "regexp"
 "strings"
 )

 func validHost(host string) bool {
 host = strings.Trim(host, " ")

 re, _ := regexp.Compile(`^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$`)
 if re.MatchString(host) {
 return true
 }
 return false
 }

 func main() {
 host1 := "socketloop.com"

 vHost := validHost(host1)

 fmt.Printf("%s is a valid hostname : %v \n", host1, vHost)

 host2 := "socketloop_com"

 vHost2 := validHost(host2)

 fmt.Printf("%s is a valid hostname : %v \n", host2, vHost2)

 host3 := "socketloop/com"

 vHost3 := validHost(host3)

 fmt.Printf("%s is a valid hostname : %v \n", host3, vHost3)

 host4 := "www.socketloop.com"

 vHost4 := validHost(host4)

 fmt.Printf("%s is a valid hostname : %v \n", host4, vHost4)

 }

Output :

socketloop.com is a valid hostname : true

socketloop_com is a valid hostname : false

socketloop/com is a valid hostname : false

www.socketloop.com is a valid hostname : true