Add SetDTLSCustomCipherSuite to SettingEngine

Resolves #2512

dtlstransport.go

@@ -318,6 +318,7 @@ func (t *DTLSTransport) Start(remoteParameters DTLSParameters) error {
 			ClientAuth:         dtls.RequireAnyClientCert,
 			LoggerFactory:      t.api.settingEngine.LoggerFactory,
 			InsecureSkipVerify: !t.api.settingEngine.dtls.disableInsecureSkipVerify,
+			CustomCipherSuites: t.api.settingEngine.dtls.customCipherSuites,
 		}, nil
 	}
 

settingengine.go

@@ -72,6 +72,7 @@ type SettingEngine struct {
 		clientCAs                 *x509.CertPool
 		rootCAs                   *x509.CertPool
 		keyLogWriter              io.Writer
+		customCipherSuites        func() []dtls.CipherSuite
 	}
 	sctp struct {
 		maxReceiveBufferSize uint32
@@ -434,3 +435,9 @@ func (e *SettingEngine) SetDTLSKeyLogWriter(writer io.Writer) {
 func (e *SettingEngine) SetSCTPMaxReceiveBufferSize(maxReceiveBufferSize uint32) {
 	e.sctp.maxReceiveBufferSize = maxReceiveBufferSize
 }
+
+// SetDTLSCustomerCipherSuites allows the user to specify a list of DTLS CipherSuites.
+// This allow usage of Ciphers that are reserved for private usage.
+func (e *SettingEngine) SetDTLSCustomerCipherSuites(customCipherSuites func() []dtls.CipherSuite) {
+	e.dtls.customCipherSuites = customCipherSuites
+}