Add warning on using old version of XTLS

And checks param `fingerprint` also

infra/conf/transport_internet.go

@@ -458,6 +458,7 @@ type XTLSConfig struct {
 	MaxVersion                       string            `json:"maxVersion"`
 	CipherSuites                     string            `json:"cipherSuites"`
 	PreferServerCipherSuites         bool              `json:"preferServerCipherSuites"`
+	Fingerprint                      string            `json:"fingerprint"`
 	RejectUnknownSNI                 bool              `json:"rejectUnknownSni"`
 	PinnedPeerCertificateChainSha256 *[]string         `json:"pinnedPeerCertificateChainSha256"`
 }
@@ -487,6 +488,9 @@ func (c *XTLSConfig) Build() (proto.Message, error) {
 	config.MaxVersion = c.MaxVersion
 	config.CipherSuites = c.CipherSuites
 	config.PreferServerCipherSuites = c.PreferServerCipherSuites
+	if c.Fingerprint != "" {
+		return nil, newError(`Old version of XTLS does not support fingerprint. Please use flow "xtls-rprx-vision" with "tls & tlsSettings" instead.`)
+	}
 	config.RejectUnknownSni = c.RejectUnknownSNI
 
 	if c.PinnedPeerCertificateChainSha256 != nil {
@@ -500,6 +504,8 @@ func (c *XTLSConfig) Build() (proto.Message, error) {
 		}
 	}
 
+	newError(`You are using an old version of XTLS, which is deprecated now and will be removed soon. Please use flow "xtls-rprx-vision" with "tls & tlsSettings" instead.`).AtWarning().WriteToLog()
+
 	return config, nil
 }