sctp_disposition_t sctp_sf_do_9_2_shut_ctsn(struct net *net,
					   const struct sctp_endpoint *ep,
					   const struct sctp_association *asoc,
					   const sctp_subtype_t type,
					   void *arg,
					   sctp_cmd_seq_t *commands)
{
	struct sctp_chunk *chunk = arg;
	sctp_shutdownhdr_t *sdh;
	__u32 ctsn;

	if (!sctp_vtag_verify(chunk, asoc))
		return sctp_sf_pdiscard(net, ep, asoc, type, arg, commands);

	/* Make sure that the SHUTDOWN chunk has a valid length. */
	if (!sctp_chunk_length_valid(chunk,
				      sizeof(struct sctp_shutdown_chunk_t)))
		return sctp_sf_violation_chunklen(net, ep, asoc, type, arg,
						  commands);

	sdh = (sctp_shutdownhdr_t *)chunk->skb->data;
	ctsn = ntohl(sdh->cum_tsn_ack);

	if (TSN_lt(ctsn, asoc->ctsn_ack_point)) {
		SCTP_DEBUG_PRINTK("ctsn %x\n", ctsn);
		SCTP_DEBUG_PRINTK("ctsn_ack_point %x\n", asoc->ctsn_ack_point);
		return SCTP_DISPOSITION_DISCARD;
	}

	/* If Cumulative TSN Ack beyond the max tsn currently
	 * send, terminating the association and respond to the
	 * sender with an ABORT.
	 */
	if (!TSN_lt(ctsn, asoc->next_tsn))
		return sctp_sf_violation_ctsn(net, ep, asoc, type, arg, commands);

	/* verify, by checking the Cumulative TSN Ack field of the
	 * chunk, that all its outstanding DATA chunks have been
	 * received by the SHUTDOWN sender.
	 */
	sctp_add_cmd_sf(commands, SCTP_CMD_PROCESS_CTSN,
			SCTP_BE32(sdh->cum_tsn_ack));

	return SCTP_DISPOSITION_CONSUME;
}

Unknown