Function visit

main.go:218–389

visit visits a url and times the interaction. If the response is a 30x, visit follows the redirect.

(url *url.URL)

// visit visits a url and times the interaction.
// If the response is a 30x, visit follows the redirect.
func visit(url *url.URL) {
	req := newRequest(httpMethod, url, postBody)

	var t0, t1, t2, t3, t4, t5, t6 time.Time

	trace := &httptrace.ClientTrace{
		DNSStart: func(_ httptrace.DNSStartInfo) { t0 = time.Now() },
		DNSDone:  func(_ httptrace.DNSDoneInfo) { t1 = time.Now() },
		ConnectStart: func(_, _ string) {
			if t1.IsZero() {
				// connecting to IP
				t1 = time.Now()
			}
		},
		ConnectDone: func(net, addr string, err error) {
			if err != nil {
				log.Fatalf("unable to connect to host %v: %v", addr, err)
			}
			t2 = time.Now()

			printf("\n%s%s\n", color.GreenString("Connected to "), color.CyanString(addr))
		},
		GotConn:              func(_ httptrace.GotConnInfo) { t3 = time.Now() },
		GotFirstResponseByte: func() { t4 = time.Now() },
		TLSHandshakeStart:    func() { t5 = time.Now() },
		TLSHandshakeDone:     func(_ tls.ConnectionState, _ error) { t6 = time.Now() },
	}
	req = req.WithContext(httptrace.WithClientTrace(context.Background(), trace))

	tr := &http.Transport{
		Proxy:                 http.ProxyFromEnvironment,
		MaxIdleConns:          100,
		IdleConnTimeout:       90 * time.Second,
		TLSHandshakeTimeout:   10 * time.Second,
		ExpectContinueTimeout: 1 * time.Second,
		ForceAttemptHTTP2:     true,
	}

	switch {
	case fourOnly:
		tr.DialContext = dialContext("tcp4")
	case sixOnly:
		tr.DialContext = dialContext("tcp6")
	}

	switch url.Scheme {
	case "https":
		host, _, err := net.SplitHostPort(req.Host)
		if err != nil {
			host = req.Host
		}

		tr.TLSClientConfig = &tls.Config{
			ServerName:         host,
			InsecureSkipVerify: insecure,
			Certificates:       readClientCert(clientCertFile),
			MinVersion:         tls.VersionTLS12,
		}