Golang URL Tracer

tracer.go

package main

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

// TransportWrapper wraps the http.Transport structure to allow us to record the
// URLs which we are redirected through
type TransportWrapper struct {
	*http.Transport
}

// RoundTrip executes a single HTTP transaction, returning
// a Response for the provided Request.
func (t *TransportWrapper) RoundTrip(req *http.Request) (*http.Response, error) {
	// Use the default transport we set
	transport := t.Transport

	if transport == nil {
		transport = http.DefaultTransport.(*http.Transport)
	}

	resp, err := transport.RoundTrip(req)
	if err != nil {
		return resp, err
	}

	// Record the redirects that we followed
	if (resp.StatusCode >= 300) && (resp.StatusCode <= 399) {
		log.Printf("Status: %d, Base URL: %s\n", resp.StatusCode, req.URL.Host)
	}
	return resp, err
}

func main() {
	log.SetPrefix("[URL Tracer] ")

	t := &TransportWrapper{
		Transport: http.DefaultTransport.(*http.Transport),
	}

	client := &http.Client{
		Transport: t,
		Timeout:   5 * time.Second,
	}

	_, err := client.Get("https://ge.service-now.com")
	if err != nil {
		log.Panicln(err)
	}
}