Convert device username to dynamic field to squeeze out a little more…

… RAM

devicetracker_component.cc

@@ -391,7 +391,8 @@ void kis_tracked_device_base::register_fields() {
     RegisterField("kismet.device.base.macaddr", "mac address", &macaddr);
     RegisterField("kismet.device.base.phyname", "phy name", &phyname);
     RegisterField("kismet.device.base.name", "printable device name", &devicename);
-    RegisterField("kismet.device.base.username", "user name", &username);
+    username_id = 
+        RegisterDynamicField("kismet.device.base.username", "user name", &username);
     RegisterField("kismet.device.base.commonname", 
             "common name alias of custom or device names", &commonname);
     RegisterField("kismet.device.base.type", "printable device type", &type_string);

devicetracker_component.h

@@ -291,12 +291,13 @@ class kis_tracked_device_base : public tracker_component {
             [this](std::string i) -> bool {
 
             // Override the common name if there's no username
-            if (get_username() == "") 
-                set_commonname(i);
+            if (has_username())
+                if (get_username() == "")
+                    set_commonname(i);
             return true;
             });
 
-    __ProxyL(username, std::string, std::string, std::string, username,
+    __ProxyDynamicL(username, std::string, std::string, std::string, username, username_id,
             [this](std::string i) -> bool {
 
             // Always override the common name
@@ -463,6 +464,7 @@ class kis_tracked_device_base : public tracker_component {
 
     // User name for arbitrary naming
     std::shared_ptr<TrackerElementString> username;
+    int username_id;
 
     // Common name connected via preserialize
     std::shared_ptr<TrackerElementString> commonname;