go - 为什么golang Lookup*** 函数不能提供服务器参数？

Question

对于nslookup 命令，它有nslookupsomewhere.com some.dns.server。

但是，golang dnsclient 似乎只从 /etc/resolv.conf

加载配置

此处代码:https://golang.org/src/net/dnsclient_unix.go#L225

golang 标准库是否提供类似func LookupTXT(name string, dnsServer string) (txt []string, err error) ?

要求:1.不要更改默认的/etc/resolv.conf。

Answer 1

@holys

"github.com/miekg/dns is too heavy for me"

没那么重:

package main

import (
    "log"

    "github.com/miekg/dns"
)

func main() {

    target := "microsoft.com"
    server := "8.8.8.8"

    c := dns.Client{}
    m := dns.Msg{}
    m.SetQuestion(target+".", dns.TypeA)
    r, t, err := c.Exchange(&m, server+":53")
    if err != nil {
        log.Fatal(err)
    }
    log.Printf("Took %v", t)
    if len(r.Answer) == 0 {
        log.Fatal("No results")
    }
    for _, ans := range r.Answer {
        Arecord := ans.(*dns.A)
        log.Printf("%s", Arecord.A)
    }
}

运行时，您应该看到:

$ go run dns.go
2015/07/26 00:24:46 Took 16.138928ms
2015/07/26 00:24:46 134.170.188.221
2015/07/26 00:24:46 134.170.185.46