package main

import (
    "fmt"
    "net"
)

func main() {
    // s := "[::1]:9000"
    s := "localhost:9000"
    host, port, err := net.SplitHostPort(s)
    if err != nil {
        fmt.Printf("error: %s\n", err)
    } else {
        fmt.Printf("host: %s, port: %s\n", host, port)
    }
}