use tls.Config.ServerName for the passing the hostname around

internal/handshake/crypto_setup_client.go

@@ -69,10 +69,9 @@ var (
 // NewCryptoSetupClient creates a new CryptoSetup instance for a client
 func NewCryptoSetupClient(
 	cryptoStream io.ReadWriter,
-	hostname string,
 	connID protocol.ConnectionID,
 	version protocol.VersionNumber,
-	tlsConfig *tls.Config,
+	tlsConf *tls.Config,
 	params *TransportParameters,
 	paramsChan chan<- TransportParameters,
 	handshakeEvent chan<- struct{},
@@ -87,10 +86,10 @@ func NewCryptoSetupClient(
 	divNonceChan := make(chan struct{})
 	cs := &cryptoSetupClient{
 		cryptoStream:   cryptoStream,
-		hostname:       hostname,
+		hostname:       tlsConf.ServerName,
 		connID:         connID,
 		version:        version,
-		certManager:    crypto.NewCertManager(tlsConfig),
+		certManager:    crypto.NewCertManager(tlsConf),
 		params:         params,
 		keyDerivation:  crypto.DeriveQuicCryptoAESKeys,
 		nullAEAD:       nullAEAD,

internal/handshake/crypto_setup_client_test.go

@@ -2,6 +2,7 @@ package handshake
 
 import (
 	"bytes"
+	"crypto/tls"
 	"crypto/x509"
 	"encoding/binary"
 	"errors"
@@ -121,10 +122,9 @@ var _ = Describe("Client Crypto Setup", func() {
 		handshakeEvent = make(chan struct{}, 2)
 		csInt, err := NewCryptoSetupClient(
 			stream,
-			"hostname",
 			protocol.ConnectionID{1, 2, 3, 4, 5, 6, 7, 8},
 			version,
-			nil,
+			&tls.Config{ServerName: "hostname"},
 			&TransportParameters{IdleTimeout: protocol.DefaultIdleTimeout},
 			paramsChan,
 			handshakeEvent,