BLE Reject new devices attempting to pair, only allow old bonded device

[rfleming]

Hi All,

I am running nrfConnect SDK v1.8.0 ad started a new sample LBS project. I ultimately want to have 3 devices, 1 being a Central and 2 Peripherals both running LBS. This will be reworked and extended in the future but for now that is fine.

My plan is to initially using the LBS peripheral app on my nrf52840 devkit set it up to allow a single mobile phone to connect and bond. Then reject any new pairing attempts by other phones or devices. If I remove the bonding on the device it will allow phones to pair and bond once again.

Currently, by default it allows only 1 device to bond, but once that device disconnects a new device can pair and hold the connection hostage. While the new device cannot be bonded, it still holds the connection hostage and my other device cannot re-establish a connection. Once I disconnect the new device, my old one can connect and resume its bonded state as it once was.

Thus far for code, I added the bonded device check on boot and load this into a variable so I knows its address.

 

struct
{
	int count;
	bt_addr_le_t addr;
} Bonded;

static void verify_bond(const struct bt_bond_info *info, void *user_data)
{
	Bonded.count++;
	bt_addr_le_copy(&Bonded.addr, &info->addr);

	char str[32];
	bt_addr_to_str(&info->addr.a, str, 18);
	
	
bt_foreach_bond(BT_ID_DEFAULT, verify_bond, NULL);

I also extended the connected callback function to reject all new connections. Though unfortunately as you can see in my printk statements, I am trying to see which address to use to know what to reject the connection based on. I know that all my addresses coming through are doing to be set to Random/Private addressing, so I can't take them on face value.

static void connected(struct bt_conn *conn, uint8_t err)
{
	if (err)
	{
		printk("Connection failed (err %u)\n", err);
		return;
	}

	printk("Connected\n");

	dk_set_led_on(CON_STATUS_LED);

	err = bt_conn_disconnect(conn, BT_HCI_ERR_REMOTE_USER_TERM_CONN);
	if (err)
	{
		printk("Disconnection failed (err %d).\n", err);
	}
	else
	{
		char str[32];
		bt_addr_to_str(&conn->le.dst.a, str, 18);
		printk("dst: %s\n", str);

		bt_addr_to_str(&conn->le.init_addr.a, str, 18);
		printk("init: %s\n", str);

		bt_addr_to_str(&conn->le.resp_addr.a, str, 18);
		printk("resp: %s\n", str);

		printk("Disconnection forced success\n");
	}
}

What would be the more appropriate way to do this? I personally don't actually know if the "bond" value is actually my genuine mac address for my device either, or its some special number thingy.

[Simonr]

Hi Ryan

I think what you're looking for is the Connection Management API in the nRFConnect SDK. As long as you store the first connected central's data you can compare it in the next CONNECTED event and trigger a disconnect if it doesn't match.

Best regards,

Simon