golang set dns

With the rapid development of the Internet, the importance of DNS (Domain Name System) has been paid more and more attention. DNS is a service that resolves domain names into IP addresses. Finding the IP address corresponding to a domain name is the basis for network communication.

In Golang, the way to set DNS is to modify the properties of Dialer.

The first thing to make clear is that the Dialer.Dial() method is generally used when creating a network connection in Golang. If the Dialer is not explicitly specified, the default Dialer will be used. Therefore, you need to create a customized Dialer first when setting up DNS.

The following is a sample code:

package main

import (
    "net"
    "net/http"
    "time"
)

func main() {
    tr := &http.Transport{
        DialContext: (&net.Dialer{
            Timeout:   30 * time.Second,
            KeepAlive: 30 * time.Second,
            DualStack: true,
        }).DialContext,
        MaxIdleConns:          100,
        IdleConnTimeout:       90 * time.Second,
        TLSHandshakeTimeout:   10 * time.Second,
        ExpectContinueTimeout: 1 * time.Second,
    }

    client := &http.Client{
        Transport: tr,
    }

    // 设置DNS
    resolver := &net.Resolver{
        PreferGo: true,
        Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
            d := &net.Dialer{Timeout: 5 * time.Second}
            return d.DialContext(ctx, "udp", "192.168.0.1:53")
        },
    }

    // 使用定制化的Dialer和Resolver
    tr.DialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
        host, port, err := net.SplitHostPort(addr)
        if err != nil {
            return nil, err
        }
        ips, err := resolver.LookupIP(ctx, network, host)
        if err != nil {
            return nil, err
        }
        return (&net.Dialer{
            Timeout:   30 * time.Second,
            KeepAlive: 30 * time.Second,
            DualStack: true,
        }).DialContext(ctx, network, net.JoinHostPort(ips[0].String(), port))
    }

    // 使用client发送请求
    resp, err := client.Get("http://google.com")
    if err != nil {
        panic(err)
    }

    defer resp.Body.Close()

    fmt.Println(resp.Status)
}

In the above code, we implement the function of setting DNS by creating a customized Resolver and specifying the Resolver in Dialer.

It should be noted that the DualStack attribute in Dialer indicates whether it supports IPv4 and IPv6 dual stack. When using a customized Dialer, it should be set according to actual needs. In addition, the IP address for setting DNS needs to be specified according to the network environment and needs.

Through the introduction to DNS settings in Golang, we learned how to use customized Dialer and Resolver to set DNS, which is very important for network communication in certain scenarios. At the same time, it is also necessary to note that adjustments need to be made according to specific conditions in actual use.

The above is the detailed content of golang set dns. For more information, please follow other related articles on the PHP Chinese website!