Allow clients to request a configured EAP method via EAP-Nak

src/libcharon/encoding/payloads/eap_payload.c

@@ -336,7 +336,8 @@ static void write_type(bio_writer_t *writer, eap_type_t type, u_int32_t vendor,
 /*
  * Described in header
  */
-eap_payload_t *eap_payload_create_nak(u_int8_t identifier, bool expanded)
+eap_payload_t *eap_payload_create_nak(u_int8_t identifier, eap_type_t type,
+									  u_int32_t vendor, bool expanded)
 {
 	enumerator_t *enumerator;
 	eap_type_t reg_type;
@@ -356,6 +357,11 @@ eap_payload_t *eap_payload_create_nak(u_int8_t identifier, bool expanded)
 	enumerator = charon->eap->create_enumerator(charon->eap, EAP_PEER);
 	while (enumerator->enumerate(enumerator, &reg_type, &reg_vendor))
 	{
+		if ((type && type != reg_type) ||
+			(type && vendor && vendor != reg_vendor))
+		{	/* the preferred type is only sent if we actually find it */
+			continue;
+		}
 		if (!reg_vendor || expanded)
 		{
 			write_type(writer, reg_type, reg_vendor, expanded);

src/libcharon/encoding/payloads/eap_payload.h

@@ -127,10 +127,13 @@ eap_payload_t *eap_payload_create_code(eap_code_t code, u_int8_t identifier);
  * Creates an eap_payload_t EAP_RESPONSE containing an EAP_NAK.
  *
  * @param identifier	EAP identifier to use in payload
+ * @param type			preferred auth type, 0 to send all supported types
+ * @param vendor		vendor identifier for auth type, 0 for default
  * @param expanded		TRUE to send an expanded Nak (as response to an expanded
  * 						request, i.e. one with vendor specific type)
  * @return 				eap_payload_t object
  */
-eap_payload_t *eap_payload_create_nak(u_int8_t identifier, bool expanded);
+eap_payload_t *eap_payload_create_nak(u_int8_t identifier, eap_type_t type,
+									  u_int32_t vendor, bool expanded);
 
 #endif /** EAP_PAYLOAD_H_ @}*/

src/libcharon/plugins/eap_peap/eap_peap_peer.c

@@ -151,7 +151,7 @@ METHOD(tls_application_t, process, status_t,
 		if (!this->ph2_method)
 		{
 			DBG1(DBG_IKE, "EAP method not supported");
-			this->out = eap_payload_create_nak(in->get_identifier(in),
+			this->out = eap_payload_create_nak(in->get_identifier(in), 0, 0,
 											   received_vendor != 0);
 			in->destroy(in);
 			return NEED_MORE;

src/libcharon/plugins/eap_ttls/eap_ttls_peer.c

@@ -192,7 +192,7 @@ METHOD(tls_application_t, process, status_t,
 		if (!this->method)
 		{
 			DBG1(DBG_IKE, "EAP method not supported");
-			this->out = eap_payload_create_nak(in->get_identifier(in),
+			this->out = eap_payload_create_nak(in->get_identifier(in), 0, 0,
 											   received_vendor != 0);
 			in->destroy(in);
 			return NEED_MORE;

src/libcharon/sa/ikev2/authenticators/eap_authenticator.c

@@ -336,8 +336,8 @@ static eap_payload_t* server_process_eap(private_eap_authenticator_t *this,
 static eap_payload_t* client_process_eap(private_eap_authenticator_t *this,
 										 eap_payload_t *in)
 {
-	eap_type_t type;
+	eap_type_t type, conf_type;
-	u_int32_t vendor;
+	u_int32_t vendor, conf_vendor;
 	auth_cfg_t *auth;
 	eap_payload_t *out;
 	identification_t *id;
@@ -373,7 +373,7 @@ static eap_payload_t* client_process_eap(private_eap_authenticator_t *this,
 		 * EAP method (types 3-253, 255) */
 		DBG1(DBG_IKE, "%N not supported, sending EAP_NAK",
 			 eap_type_names, type);
-		return eap_payload_create_nak(in->get_identifier(in), FALSE);
+		return eap_payload_create_nak(in->get_identifier(in), 0, 0, FALSE);
 	}
 	if (this->method == NULL)
 	{
@@ -387,11 +387,31 @@ static eap_payload_t* client_process_eap(private_eap_authenticator_t *this,
 			DBG1(DBG_IKE, "server requested %N authentication (id 0x%02X)",
 				 eap_type_names, type, in->get_identifier(in));
 		}
+		auth = this->ike_sa->get_auth_cfg(this->ike_sa, TRUE);
+		conf_type = (uintptr_t)auth->get(auth, AUTH_RULE_EAP_TYPE);
+		conf_vendor = (uintptr_t)auth->get(auth, AUTH_RULE_EAP_VENDOR);
+		if (conf_type != EAP_NAK &&
+		   (conf_type != type || conf_vendor != vendor))
+		{
+			if (conf_vendor)
+			{
+				DBG1(DBG_IKE, "requesting EAP method %d-%d, sending EAP_NAK",
+					 conf_type, conf_vendor);
+			}
+			else
+			{
+				DBG1(DBG_IKE, "requesting %N authentication, sending EAP_NAK",
+					 eap_type_names, conf_type);
+			}
+			return eap_payload_create_nak(in->get_identifier(in), conf_type,
+										  conf_vendor, vendor != 0);
+		}
 		this->method = load_method(this, type, vendor, EAP_PEER);
 		if (!this->method)
 		{
 			DBG1(DBG_IKE, "EAP method not supported, sending EAP_NAK");
-			return eap_payload_create_nak(in->get_identifier(in), vendor != 0);
+			return eap_payload_create_nak(in->get_identifier(in), 0, 0,
+										  vendor != 0);
 		}
 	}