How to Perform a LookupTXT in Golang Without Changing /etc/resolv.conf?

LookupTXT Function in Golang without Modifying /etc/resolv.conf

The standard Golang library does not provide a direct function equivalent to LookupTXT that allows specifying a custom DNS server. The reason for this is that the DNS client relies on the configuration from /etc/resolv.conf for DNS server information.

However, there are several options to achieve what you need while adhering to the requirement of not modifying /etc/resolv.conf.

Using a Custom DNS Resolver:

One approach is to use a custom DNS resolver library that supports specifying a specific DNS server. For example, the github.com/miekg/dns library provides the flexibility to set a custom server IP in the dns.Client object. The following code demonstrates how to use this library:

import (
    "log"
    "net"

    "github.com/miekg/dns"
)

func main() {
    target := "microsoft.com"
    server := "8.8.8.8"

    // Create a new DNS client with a custom server.
    c := dns.Client{Net: "udp", Server: server}

    // Build a request message.
    m := dns.Msg{}
    m.SetQuestion(target+".", dns.TypeTXT)

    // Exchange the request and receive the response.
    r, _, err := c.Exchange(&m, server+":53")
    if err != nil {
        log.Fatal(err)
    }

    // Process the response.
    if len(r.Answer) == 0 {
        log.Fatal("No results")
    }
    for _, ans := range r.Answer {
        TXTrecord := ans.(*dns.TXT)
        for _, txt := range TXTrecord.Txt {
            log.Println(txt)
        }
    }
}

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