golang 强制 net/http 客户端使用 IPv4/IPv6

Question

我正在使用 go1.11 net/http 并想检测域是否仅支持 ipv6。

你做了什么？

我创建了自己的 DialContext，因为我想检测域是否仅支持 ipv6。下面的代码

package main
import (
    "errors"
    "fmt"
    "net"
    "net/http"
    "syscall"
    "time"
)
func ModifiedTransport() {
    var MyTransport = &http.Transport{
        DialContext: (&net.Dialer{
            Timeout:   30 * time.Second,
            KeepAlive: 30 * time.Second,
            DualStack: false,
            Control: func(network, address string, c syscall.RawConn) error {
                if network == "ipv4" {
                    // I want to  cancel connection here client.Get("http://myexample.com") return a non-nil err.
                    return errors.New("you should not use ipv4")
                }
                return nil
            },
        }).DialContext,
        MaxIdleConns:          100,
        IdleConnTimeout:       90 * time.Second,
        TLSHandshakeTimeout:   10 * time.Second,
        ExpectContinueTimeout: 1 * time.Second,
    }
    var myClient = http.Client{Transport: MyTransport}
    resp, myerr := myClient.Get("http://www.github.com")
    if myerr != nil {
        fmt.Println("request error")
        return 
    }
    var buffer = make([]byte, 1000)
    resp.Body.Read(buffer)
    fmt.Println(string(buffer))
}
func main(){
    ModifiedTransport();
}

我现在不知道如何关闭请求，即使我可以进入 network == "ipv4"。

加法

Python 可以通过 Force requests to use IPv4 / IPv6 解决问题.我不知道如何在 golang 中做到这一点。有人可以帮助我吗？非常感谢!

Answer 1

传递给 Control 函数的 network 是用于 IPv4 连接的 tcp4 或用于 IPv6 的 tcp6连接，如果您正在建立传出 TCP 连接。

来自 type Dialer 的评论:

        // Network and address parameters passed to Control method are not
        // necessarily the ones passed to Dial. For example, passing "tcp" to Dial
        // will cause the Control function to be called with "tcp4" or "tcp6".

(在非 TCP 连接的情况下，other strings 是可能的。)

Known networks are "tcp", "tcp4" (IPv4-only), "tcp6" (IPv6-only), "udp", "udp4" (IPv4-only), "udp6" (IPv6-only), "ip", "ip4" (IPv4-only), "ip6" (IPv6-only), "unix", "unixgram" and "unixpacket".