Basic Golang example for host spoofing on HTTP requests.

spoof.go

package main

import (
	"context"
	"fmt"
	"io/ioutil"
	"net"
	"net/http"
)

func main() {
	client := &http.Client{
		Transport: &http.Transport{
			DialContext: func(ctx context.Context, network, addr string) (net.Conn, error) {
				return (&net.Dialer{}).DialContext(ctx, network, "127.0.0.1:80")
			},
		},
	}
	req, err := http.NewRequest("GET", "http://default-hello-world.default.example.com/test", nil)
	if err != nil {
		panic(err)
	}
	req.Header.Add("Content-Type", "application/json")
	res, err := client.Do(req)
	if err != nil {
		panic(err)
	}
	defer res.Body.Close()
	body, err := ioutil.ReadAll(res.Body)
	if err != nil {
		panic(err)
	}
	fmt.Println(string(body))
}