rtr: Respond with error if ASPA announcement PDU contains no providers

Brias · tanneberger · commit fc925dc07336 · 2025-07-23T15:02:08.000+02:00
- Draft `8210bis` version 21; Section 5.12. states that an ASPA
  announcement PDU must always contain at least one provider
  autonomous system number
- If an announcement doesn't contain any provider autonomous
  system numbers an error `ASPA Provider List Error (9)` is
  sent to the cache server and the transport connection is
  closed
diff --git a/rtrlib/rtr/packets.c b/rtrlib/rtr/packets.c
@@ -1090,6 +1090,18 @@ static int rtr_compute_update_aspa_table(struct rtr_socket *rtr_socket, struct a
 	}
 
 	for (size_t i = 0; i < pdu_count; i++) {
+		struct pdu_aspa *pdu = aspa_pdus[i];
+		bool is_announcement = pdu->flags & 1;
+
+		// TODO: Add test
+		if (is_announcement && rtr_aspa_provider_count(pdu) == 0) {
+			RTR_DBG1("ASPA announcement doesn't contain any provider autonomous system numbers");
+			rtr_send_error_pdu_from_host(rtr_socket, pdu, pdu->len, INCORRECT_ASPA_PROVIDER_LIST, NULL, 0);
+			rtr_change_socket_state(rtr_socket, RTR_ERROR_FATAL);
+
+			return RTR_ERROR;
+		}
+
 		rtr_aspa_pdu_2_aspa_operation(aspa_pdus[i], &operations[i]);
 		operations[i].index = i;
 	}
diff --git a/rtrlib/rtr/rtr_pdus.h b/rtrlib/rtr/rtr_pdus.h
@@ -12,6 +12,7 @@ enum pdu_error_type {
 	WITHDRAWAL_OF_UNKNOWN_RECORD = 6,
 	DUPLICATE_ANNOUNCEMENT = 7,
 	UNEXPECTED_PROTOCOL_VERSION = 8,
+	INCORRECT_ASPA_PROVIDER_LIST = 9,
 	PDU_TOO_BIG = 32
 };
 
