debug http requests for oauth

debugoauth,go

type DebugRoundTripper struct {
	transport http.RoundTripper
	out  io.Writer
}

func (d *DebugRoundTripper) RoundTrip(req *http.Request) (*http.Response, error) {
	outreq, _ := httputil.DumpRequestOut(req, false)
	fmt.Fprintf(os.Stderr, "REQOUT:\n%q\n", outreq)

	resp, err := d.transport.RoundTrip(req)
	if resp != nil {
		outresp, _ := httputil.DumpResponse(resp, false)
		fmt.Fprintf(os.Stderr, "RESP:\n%q\n", outresp)
	}
	return resp, err
}

func main() {
  // For appengine
  client := &http.Client{Transport: &DebugRoundTripper{&urlfetch.Transport{ctx, false}, os.Stderr}}

  // For non-appengine
  client := &http.Client{Transport: &DebugRoundTripper{http.DefaultTransport, os.Stderr}}

  ctx = context.WithValue(ctx, oauth2.HTTPClient, client)
}