net/httptrace

package main

import (
    "fmt"
    "net/http"
    "net/http/httptrace"
    "log"
    "io/ioutil"
)

func main() {
    req, _ := http.NewRequest("GET", "http://example.com", nil)

    // 创建客户端请求跟踪
    trace := &httptrace.ClientTrace{
        GotConn: func(connInfo httptrace.GotConnInfo) {
            fmt.Printf("Got Conn: %+v\n", connInfo)
        },
        DNSStart: func(info httptrace.DNSStartInfo) {
          fmt.Println(info.Host)
        },
        ConnectStart: func(network, addr string) {
          fmt.Println(network)
          fmt.Println(addr)
        },
        DNSDone: func(dnsInfo httptrace.DNSDoneInfo) {
            fmt.Printf("DNS Info: %+v\n", dnsInfo)
        },
    }
    // 请求追踪
    req = req.WithContext(httptrace.WithClientTrace(req.Context(), trace))
    resp, err := http.DefaultTransport.RoundTrip(req)
    if err != nil {
        log.Fatal(err)
    }
    data,_ := ioutil.ReadAll(resp.Body)
    fmt.Println(string(data))
}