readfile_dns.go

package main

import (
	"bufio"
	"fmt"
	"io"
	"net"
	"os"
	"strings"
)

func dns(domain string) {
	ns, err := net.LookupHost(domain)
	if err != nil {
		//fmt.Fprintf(os.Stderr, "Err: %s", err.Error())
	} else {
		fmt.Print(domain)
	}

	for _, n := range ns {
		fmt.Fprintf(os.Stdout, "--%s\n", n)
	}
}
func main() {
	f, err := os.Open("dns.txt")
	if err != nil {
		fmt.Print(err)
	}
	defer f.Close()
	buf := bufio.NewReader(f)
	for {
		line, err := buf.ReadString('\n')
		line = strings.TrimSpace(line)
		if err != nil {
			if err == io.EOF {
				break
			}
			fmt.Print(err)
		}
		domain := line + "lenovo.com.cn"
		go dns(domain)
	}
}