static int trans_ack()

in nimble/host/mesh/src/transport.c [813:888]

• 57 lines of code
• 11 McCabe index (conditional complexity)

static int trans_ack(struct bt_mesh_net_rx *rx, uint8_t hdr,
		     struct os_mbuf *buf, uint64_t *seq_auth)
{
	struct seg_tx *tx;
	unsigned int bit;
	uint32_t ack;
	uint16_t seq_zero;
	uint8_t obo;

	if (buf->om_len < 6) {
		BT_ERR("Too short ack message");
		return -EINVAL;
	}

	seq_zero = net_buf_simple_pull_be16(buf);
	obo = seq_zero >> 15;
	seq_zero = (seq_zero >> 2) & TRANS_SEQ_ZERO_MASK;

	if (IS_ENABLED(CONFIG_BT_MESH_FRIEND) && rx->friend_match) {
		BT_DBG("Ack for LPN 0x%04x of this Friend", rx->ctx.recv_dst);
		/* Best effort - we don't have enough info for true SeqAuth */
		*seq_auth = SEQ_AUTH(BT_MESH_NET_IVI_RX(rx), seq_zero);
		return 0;
	}

	ack = net_buf_simple_pull_be32(buf);

	BT_DBG("OBO %u seq_zero 0x%04x ack 0x%08x", obo, seq_zero,
	       (unsigned) ack);

	tx = seg_tx_lookup(seq_zero, obo, rx->ctx.addr);
	if (!tx) {
		BT_WARN("No matching TX context for ack");
		return -EINVAL;
	}

	if (!BT_MESH_ADDR_IS_UNICAST(tx->dst)) {
		BT_ERR("Received ack for group seg");
		return -EINVAL;
	}

	*seq_auth = tx->seq_auth;

	if (!ack) {
		BT_WARN("SDU canceled");
		seg_tx_complete(tx, -ECANCELED);
		return 0;
	}

	if (find_msb_set(ack) - 1 > tx->seg_n) {
		BT_ERR("Too large segment number in ack");
		return -EINVAL;
	}

	while ((bit = find_lsb_set(ack))) {
		if (tx->seg[bit - 1]) {
			BT_DBG("seg %u/%u acked", bit - 1, tx->seg_n);
			seg_tx_done(tx, bit - 1);
		}

		ack &= ~BIT(bit - 1);
	}

	if (tx->nack_count) {
		/* According to the Bluetooth Mesh Profile specification,
		 * section 3.5.3.3, we should reset the retransmit timer and
		 * retransmit immediately when receiving a valid ack message:
		 */
		k_work_reschedule(&tx->retransmit, K_NO_WAIT);
	} else {
		BT_DBG("SDU TX complete");
		seg_tx_complete(tx, 0);
	}

	return 0;
}