Golang Test Dial DNS

test_dial.go

package main

// GOOS=linux GOARCH=amd64 go build -o testdial test_dial.go

import (
	"flag"
	"fmt"
	"net"
	"time"
)

var options = struct {
	network string
	host string
	port int
}{
	network: "tcp",
}

func init() {
	flag.StringVar(&options.network, "network", options.network, "network type (tcp,udp)")
	flag.StringVar(&options.host, "host", "", "host name (required)")
	flag.IntVar(&options.port, "port", 0, "port (required)")
}

func main() {
	flag.Parse()
	if options.host == "" || options.port <= 0 {
		fmt.Println("both host and port must be specified")
		return
	}
	if options.network != "tcp" && options.network != "udp" {
		fmt.Println("both network type must be in [udp,tcp]")
		return
	}

	dialer := &net.Dialer{
		Timeout:       time.Second*15,
	}
	address := fmt.Sprintf("%s:%d", options.host, options.port)
	fmt.Printf("attempting to connect to (%s) %s\n", options.network, address)
	conn, err := dialer.Dial(options.network, address)
	if err != nil {
		fmt.Printf("failed to connect: %v", err)
		return
	}

	conn.Close()
	fmt.Println("successfully connected!")
}