Fix bank GUID serialization on T5 and T6 (Refs #15)

t6/scripts/tws_t6_bank.gsc

@@ -119,12 +119,43 @@ bank_request(player, args)
     level.bank_busy = false;
 }
 
+bank_guid(player)
+{
+    if (!isDefined(player))
+        return undefined;
+    // Use the persistent field populated at connection, as telemetry does.
+    guid = player.guid;
+    if (!isDefined(guid) || (typeof(guid) != "string" && typeof(guid) != "int"))
+        return undefined;
+    // Preserve string identities without numeric casts, including large GUIDs.
+    guid = "" + guid;
+    if (guid.size == 0 || guid.size > 64)
+        return undefined;
+    allowed = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_.:-";
+    for (i = 0; i < guid.size; i++)
+    {
+        found = false;
+        for (j = 0; j < allowed.size; j++)
+            if (guid[i] == allowed[j])
+                found = true;
+        if (!found)
+            return undefined;
+    }
+    return guid;
+}
+
 bank_transfer(entry, args)
 {
     player = entry.player;
+    guid = bank_guid(player);
+    if (!isDefined(guid))
+    {
+        bank_say(entry, "^3Bank player identity unavailable. Try again shortly; points unchanged.");
+        return;
+    }
     data = [];
     data["server"] = level.bank_server;
-    data["guid"] = player getGuid();
+    data["guid"] = guid;
     if (args[0] == ".b")
     {
         if (args.size != 1)