ncd: modules: net_backend_wpa_supplicant: make sure we don't give data_begins_with() an empty needle argument

ncd/modules/net_backend_wpa_supplicant.c

@@ -343,7 +343,7 @@ void process_pipe_handler_send (struct instance *o, uint8_t *data, int data_len)
     // prefix, so don't fail if there isn't one.
     size_t l1;
     size_t l2;
-    if ((l1 = data_begins_with((char *)data, data_len, o->ifname)) && (l2 = data_begins_with((char *)data + l1, data_len - l1, ": "))) {
+    if (strlen(o->ifname) > 0 && (l1 = data_begins_with((char *)data, data_len, o->ifname)) && (l2 = data_begins_with((char *)data + l1, data_len - l1, ": "))) {
         data += l1 + l2;
         data_len -= l1 + l2;
     }