Fix deleted centers not being deleted and do some work on delivery reports

src/PDUProcessor/Preprocessor/Client/DeliveryReceiptRequestProcessor.ts

@@ -0,0 +1,18 @@
+import SmppSession from "../../../SmppSession";
+import Preprocessor from "../Preprocessor";
+
+export default class DeliveryReceiptRequestProcessor extends Preprocessor {
+	private iterator: number = 0;
+
+	constructor(type: string) {
+		super(type);
+	}
+
+	processPdu(session: any, pdu: any, entity?: SmppSession | undefined): Promise<any> {
+		return new Promise<any>((resolve, reject) => {
+			if (!!pdu.command && pdu.command === "submit_sm") {
+				pdu.registered_delivery = 1;
+			}
+		});
+	}
+}