Bluetooth: Mesh: Friend node not cache for lpn which receiveing unknown app_idx

[LingaoM]

When friend node use a different application key with lpn node, the friend not cache them.
But, the spec not limited for this.

[LingaoM]

@jhedberg CC

[jhedberg]

@LingaoMeng could you provide the additional details (like a quote of the code) as you did in the original issue?

[LingaoM]

if (IS_ENABLED(CONFIG_BT_MESH_FRIEND) && rx->friend_match && !err) { 

zephyr/subsys/bluetooth/mesh/transport.c

Lines 1765 to 1801 in 7ab754d

	err = trans_seg(buf, rx, &pdu_type, &seq_auth, &seg_count);
	} else {
	seg_count = 1;
	err = trans_unseg(buf, rx, &seq_auth);
	}
	/* Notify LPN state machine so a Friend Poll will be sent. If the
	* message was a Friend Update it's possible that a Poll was already
	* queued for sending, however that's fine since then the
	* bt_mesh_lpn_waiting_update() function will return false:
	* we still need to go through the actual sending to the bearer and
	* wait for ReceiveDelay before transitioning to WAIT_UPDATE state.
	* Another situation where we want to notify the LPN state machine
	* is if it's configured to use an automatic Friendship establishment
	* timer, in which case we want to reset the timer at this point.
	*
	*/
	if (IS_ENABLED(CONFIG_BT_MESH_LOW_POWER) &&
	(bt_mesh_lpn_timer() ||
	(bt_mesh_lpn_established() && bt_mesh_lpn_waiting_update()))) {
	bt_mesh_lpn_msg_received(rx);
	}
	net_buf_simple_restore(buf, &state);
	if (IS_ENABLED(CONFIG_BT_MESH_FRIEND) && rx->friend_match && !err) {
	if (seq_auth == TRANS_SEQ_AUTH_NVAL) {
	bt_mesh_friend_enqueue_rx(rx, pdu_type, NULL,
	seg_count, buf);
	} else {
	bt_mesh_friend_enqueue_rx(rx, pdu_type, &seq_auth,
	seg_count, buf);
	}
	}
	return err;
	}

zephyr/subsys/bluetooth/mesh/transport.c

Lines 909 to 913 in 7ab754d

	BT_WARN("No matching AppKey");
	return -EINVAL;
	}