Avoid NULL string in printf on EAP method names in authenticator

In ieee802_1x_decapsulate_radius(), eap_server_get_name() may return
NULL, and it could be dereferenced depending on printf implementation.
Change it to return "unknown" instead for the case of no matching EAP
method found. This makes it easier for the callers to simply print this
in logs (which is the only use for this function).

Signed-off-by: Eytan Lifshitz <eytan.lifshitz@intel.com>

src/ap/ieee802_1x.c

@@ -1211,15 +1211,11 @@ static void ieee802_1x_decapsulate_radius(struct hostapd_data *hapd,
 		if (eap_type >= 0)
 			sm->eap_type_authsrv = eap_type;
 		os_snprintf(buf, sizeof(buf), "EAP-Request-%s (%d)",
-			    eap_type >= 0 ? eap_server_get_name(0, eap_type) :
-			    "??",
-			    eap_type);
+			    eap_server_get_name(0, eap_type), eap_type);
 		break;
 	case EAP_CODE_RESPONSE:
 		os_snprintf(buf, sizeof(buf), "EAP Response-%s (%d)",
-			    eap_type >= 0 ? eap_server_get_name(0, eap_type) :
-			    "??",
-			    eap_type);
+			    eap_server_get_name(0, eap_type), eap_type);
 		break;
 	case EAP_CODE_SUCCESS:
 		os_strlcpy(buf, "EAP Success", sizeof(buf));
@@ -2502,10 +2498,8 @@ int ieee802_1x_get_mib_sta(struct hostapd_data *hapd, struct sta_info *sta,
 	ret = os_snprintf(buf + len, buflen - len,
 			  "last_eap_type_as=%d (%s)\n"
 			  "last_eap_type_sta=%d (%s)\n",
-			  sm->eap_type_authsrv,
-			  name1 ? name1 : "",
-			  sm->eap_type_supp,
-			  name2 ? name2 : "");
+			  sm->eap_type_authsrv, name1,
+			  sm->eap_type_supp, name2);
 	if (os_snprintf_error(buflen - len, ret))
 		return len;
 	len += ret;

src/eap_server/eap_server_methods.c

@@ -153,7 +153,7 @@ void eap_server_unregister_methods(void)
  * eap_server_get_name - Get EAP method name for the given EAP type
  * @vendor: EAP Vendor-Id (0 = IETF)
  * @type: EAP method type
- * Returns: EAP method name, e.g., TLS, or %NULL if not found
+ * Returns: EAP method name, e.g., TLS, or "unknown" if not found
  *
  * This function maps EAP type numbers into EAP type names based on the list of
  * EAP methods included in the build.
@@ -167,5 +167,5 @@ const char * eap_server_get_name(int vendor, EapType type)
 		if (m->vendor == vendor && m->method == type)
 			return m->name;
 	}
-	return NULL;
+	return "unknown";
 }