handshake: use new crypto/tls 0-RTT API (#4953)

* handshake: simplify method signature of cryptoSetup.handleEvent

* use the new crypto/tls 0-RTT API

internal/protocol/encryption_level.go

@@ -1,5 +1,10 @@
 package protocol
 
+import (
+	"crypto/tls"
+	"fmt"
+)
+
 // EncryptionLevel is the encryption level
 // Default value is Unencrypted
 type EncryptionLevel uint8
@@ -28,3 +33,33 @@ func (e EncryptionLevel) String() string {
 	}
 	return "unknown"
 }
+
+func (e EncryptionLevel) ToTLSEncryptionLevel() tls.QUICEncryptionLevel {
+	switch e {
+	case EncryptionInitial:
+		return tls.QUICEncryptionLevelInitial
+	case EncryptionHandshake:
+		return tls.QUICEncryptionLevelHandshake
+	case Encryption1RTT:
+		return tls.QUICEncryptionLevelApplication
+	case Encryption0RTT:
+		return tls.QUICEncryptionLevelEarly
+	default:
+		panic(fmt.Sprintf("unexpected encryption level: %s", e))
+	}
+}
+
+func FromTLSEncryptionLevel(e tls.QUICEncryptionLevel) EncryptionLevel {
+	switch e {
+	case tls.QUICEncryptionLevelInitial:
+		return EncryptionInitial
+	case tls.QUICEncryptionLevelHandshake:
+		return EncryptionHandshake
+	case tls.QUICEncryptionLevelApplication:
+		return Encryption1RTT
+	case tls.QUICEncryptionLevelEarly:
+		return Encryption0RTT
+	default:
+		panic(fmt.Sprintf("unexpect encryption level: %s", e))
+	}
+}