package main

import (
	"flag"
	"io"
	"log"
	"net"
	"net/http"
	"os"
	"syscall"
)

var (
	uri          = flag.String("target", "https://google.com", "target url")
	netInterface = flag.String("interface", "eth0", "")
)

func main() {
	flag.Parse()

	client := &http.Client{
		Transport: Transport(*netInterface),
	}

	rc, err := client.Get(*uri)
	if err != nil {
		log.Fatal(err)
	}
	defer rc.Body.Close()

	if _, err := io.Copy(os.Stdout, rc.Body); err != nil {
		log.Fatal(err)
	}
}

func Transport(interfaceName string) *http.Transport {
	return &http.Transport{
		DialContext: (&net.Dialer{
			Control: func(network, address string, c syscall.RawConn) (err error) {
				err1 := c.Control(func(fd uintptr) {
					// need setcap cap_net_raw+ep
					err = syscall.SetsockoptString(int(fd), syscall.SOL_SOCKET, syscall.SO_BINDTODEVICE, interfaceName)
					if err != nil {
						return
					}
				})
				if err != nil {
					return err
				}
				return err1
			},
		}).DialContext,
	}
}