fix: replacing IntN old reference, reverting expected argument type t…

…o *Masquerade instead of masquerade and add function for finding provider from a given masquerade

direct.go

@@ -65,7 +65,7 @@ func (d *direct) loadCandidates(initial map[string]*Provider) {
 		// ('inside-out' Fisher-Yates)
 		sh := make([]*Masquerade, size)
 		for i := 0; i < size; i++ {
-			j := rand.Intn(i + 1) // 0 <= j <= i
+			j := rand.IntN(i + 1) // 0 <= j <= i
 			sh[i] = sh[j]
 			sh[j] = arr[i]
 		}
@@ -356,7 +356,7 @@ dialLoop:
 		// We do the full TLS connection here because in practice the domains at a given IP
 		// address can change frequently on CDNs, so the certificate may not match what
 		// we expect.
-		conn, retriable, err := d.doDial(m)
+		conn, retriable, err := d.doDial(&m.Masquerade)
 		masqueradeGood := func(good bool) bool {
 			if good {
 				m.markSucceeded()
@@ -378,7 +378,7 @@ dialLoop:
 	return nil, nil, nil, errors.New("could not dial any masquerade?")
 }
 
-func (d *direct) doDial(m *masquerade) (conn net.Conn, retriable bool, err error) {
+func (d *direct) doDial(m *Masquerade) (conn net.Conn, retriable bool, err error) {
 	op := ops.Begin("dial_masquerade")
 	defer op.End()
 	op.Set("masquerade_domain", m.Domain)
@@ -410,7 +410,7 @@ func (d *direct) doDial(m *masquerade) (conn net.Conn, retriable bool, err error
 	return
 }
 
-func (d *direct) dialServerWith(m *masquerade) (net.Conn, error) {
+func (d *direct) dialServerWith(m *Masquerade) (net.Conn, error) {
 	tlsConfig := d.frontingTLSConfig(m)
 	dialTimeout := 10 * time.Second
 	sendServerNameExtension := false
@@ -465,11 +465,20 @@ func (d *direct) verifyPeerCertificate(domain string, rawCerts [][]byte, _ [][]*
 	return nil
 }
 
+func (d *direct) findProviderFromMasquerade(m *Masquerade) *Provider {
+	for _, masquerade := range d.masquerades {
+		if masquerade.Domain == m.Domain && masquerade.IpAddress == m.IpAddress {
+			return d.providers[masquerade.ProviderID]
+		}
+	}
+	return nil
+}
+
 // frontingTLSConfig builds a tls.Config for dialing the fronting domain. This is to establish the
 // initial TCP connection to the CDN.
-func (d *direct) frontingTLSConfig(m *masquerade) *tls.Config {
-	provider := d.providers[m.ProviderID]
-	if provider.SNIConfig.UseArbitrarySNIs {
+func (d *direct) frontingTLSConfig(m *Masquerade) *tls.Config {
+	provider := d.findProviderFromMasquerade(m)
+	if provider != nil && provider.SNIConfig != nil && provider.SNIConfig.UseArbitrarySNIs {
 		randomSNIIndex := rand.IntN(len(provider.SNIConfig.ArbitrarySNIs))
 		sniDomain := provider.SNIConfig.ArbitrarySNIs[randomSNIIndex]
 		return &tls.Config{