bluetooth(4) - OpenBSD manual pages

SYNOPSIS

#include <netbt/bluetooth.h>
#include <netbt/hci.h>
#include <netbt/l2cap.h>
#include <netbt/rfcomm.h>

DESCRIPTION

Bluetooth protocol family sockets all use a sockaddr_bt structure which contains a Bluetooth Device Address (BDADDR). This consists of a six byte string in least significant byte first order.

struct sockaddr_bt {
	uint8_t		bt_len;
	sa_family_t	bt_family;
	bdaddr_t	bt_bdaddr;
	uint16_t	bt_psm;
	uint8_t		bt_channel;
};

The local address used by the socket can be set with bind(2).

OpenBSD provides support for the following devices:

Human Interface Devices

btkbd(4): Bluetooth keyboard support
btms(4): Bluetooth mouse support

PROTOCOLS

Protocols included are:

BTPROTO_HCI

This gives raw access to the Host Controller Interface of local devices using the HCI protocol as described in the Bluetooth Core Specification. Any user may open an HCI socket but there are limitations on what unprivileged users can send and receive. The local address specified by bind(2) may be used to select the device that the socket will receive packets from. If BDADDR_ANY is specified then the socket will receive packets from all devices on the system. connect(2) may be used to create connections such that packets sent with send(2) will be delivered to the specified device, otherwise sendto(2) should be used.

The bt_psm and bt_channel fields in the sockaddr_bt structure are ignored by HCI protocol code and should be set to zero.

HCI socket options:

SO_HCI_EVT_FILTER [struct hci_filter]: This filter controls which events will be received at the socket. See ⟨netbt/hci.h⟩ for available events. By default, only Command_Complete and Command_Status events are enabled.
SO_HCI_PKT_FILTER [struct hci_filter]: This filter controls the type of packets that will be received at the socket. By default, only Event packets are enabled.
SO_HCI_DIRECTION [int]: When set, this enables control messages on packets received at the socket indicating the direction of travel of the packet.

HCI sysctl(8) controls:

net.bluetooth.hci.sendspace: Default send buffer size for HCI sockets.
net.bluetooth.hci.recvspace: Default receive buffer size for HCI sockets.
net.bluetooth.hci.acl_expiry: If set, this is the time in seconds after which unused ACL data connections will be expired. If zero, connections will not be closed.
net.bluetooth.hci.memo_expiry: Time, in seconds, that the system will keep records of Bluetooth devices in the vicinity after an Inquiry Response packet has been received. This information is used for routing purposes.
net.bluetooth.hci.eventq_max: The maximum number of packets on the low level Event queue.
net.bluetooth.hci.aclrxq_max: The maximum number of packets on the low level ACL queue.
net.bluetooth.hci.scorxq_max: The maximum number of packets on the low level SCO queue.

BTPROTO_L2CAP

L2CAP sockets give sequential packet access over channels to other Bluetooth devices and make use of the bt_psm field in the sockaddr_bt structure to select the Protocol/Service Multiplexer to specify when making connections.

L2CAP socket options:

SO_L2CAP_IMTU [uint16_t]

Incoming MTU.

SO_L2CAP_OMTU [uint16_t]

Outgoing MTU (read-only).

SO_L2CAP_LM [int]

Link Mode. The following bits may be set:

L2CAP_LM_AUTH: Request authentication (pairing).
L2CAP_LM_ENCRYPT: Request encryption (includes auth).
L2CAP_LM_SECURE: Request secured link (encryption, plus change link key).

Link mode settings will be applied to the baseband link during L2CAP connection establishment. If the L2CAP connection is already established, EINPROGRESS may be returned, and it is not possible to guarantee that data already queued (from either end) will not be delivered. If the mode change fails, the L2CAP connection will be aborted.

L2CAP sysctl(8) controls:

net.bluetooth.l2cap.sendspace: Default send buffer size for L2CAP sockets.
net.bluetooth.l2cap.recvspace: Default receive buffer size for L2CAP sockets.
net.bluetooth.l2cap.rtx: Response Timeout eXpiry for L2CAP signals.
net.bluetooth.l2cap.ertx: Extended Response Timeout eXpiry for L2CAP signals.

BTPROTO_RFCOMM

RFCOMM sockets provide streamed data over Bluetooth connections and make use of the bt_psm and bt_channel fields in the sockaddr_bt structure. The channel number must be between 1 and 30 inclusive. If no PSM is specified, a default value of L2CAP_PSM_RFCOMM (0x0003) will be used.

RFCOMM socket options:

SO_RFCOMM_MTU [uint16_t]

Maximum Frame Size to use for this link.

SO_RFCOMM_LM [int]

Link Mode. The following bits may be set at any time:

RFCOMM_LM_AUTH: Request authentication (pairing).
RFCOMM_LM_ENCRYPT: Request encryption (includes auth).
RFCOMM_LM_SECURE: Request secured link (encryption, plus change link key).

Link mode settings will be applied to the baseband link during RFCOMM connection establishment. If the RFCOMM connection is already established, EINPROGRESS may be returned, and it is not possible to guarantee that data already queued (from either end) will not be delivered. If the mode change fails, the RFCOMM connection will be aborted.

RFCOMM sysctl(8) controls:

net.bluetooth.rfcomm.sendspace: Default send buffer size for RFCOMM sockets.
net.bluetooth.rfcomm.recvspace: Default receive buffer size for RFCOMM sockets.
net.bluetooth.rfcomm.default_mtu: Maximum Frame Size (N1).
net.bluetooth.ack_timeout: Acknowledgement Timer (T1).
net.bluetooth.mcc_timeout: Response Timer for Multiplexer Control Channel (T2).

BTPROTO_SCO

SCO sockets provide sequential packet access to time sensitive data channels over Bluetooth connections, typically used for audio data.

SCO socket options:

SO_SCO_MTU [uint16_t]: Maximum packet size for use on this link. This is read-only and will be set by the protocol code when a connection is made. Currently, due to limitations in the ubt(4) driver, the SCO protocol code will only accept packets with exactly this size.
SO_SCO_HANDLE [uint16_t]: Connection handle for this link. This is read-only and provided for informational purposes only.

SCO sysctl(8) controls:

net.bluetooth.sco.sendspace: Default send buffer size for SCO sockets.
net.bluetooth.sco.recvspace: Default receive buffer size for SCO sockets.

INFORMATION

The following ioctl(2) calls may be used to manipulate Bluetooth devices. The ioctl(2) must be made on BTPROTO_HCI sockets. All of the requests take a btreq structure defined as follows as their parameter and unless otherwise specified, use the btr_name field to identify the device.

struct btreq {
    char btr_name[HCI_DEVNAME_SIZE];	/* device name */

    union {
	struct {
	    bdaddr_t btri_bdaddr;	/* device bdaddr */
	    uint16_t btri_flags;	/* flags */
	    uint16_t btri_num_cmd;	/* # of free cmd buffers */
	    uint16_t btri_num_acl;	/* # of free ACL buffers */
	    uint16_t btri_num_sco;	/* # of free SCO buffers */
	    uint16_t btri_acl_mtu;	/* ACL mtu */
	    uint16_t btri_sco_mtu;	/* SCO mtu */
	    uint16_t btri_link_policy;	/* Link Policy */
	    uint16_t btri_packet_type;	/* Packet Type */
	} btri;
	struct bt_stats btrs;   /* unit stats */
    } btru;
};

#define btr_flags	btru.btri.btri_flags
#define btr_bdaddr	btru.btri.btri_bdaddr
#define btr_num_cmd	btru.btri.btri_num_cmd
#define btr_num_acl	btru.btri.btri_num_acl
#define btr_num_sco	btru.btri.btri_num_sco
#define btr_acl_mtu	btru.btri.btri_acl_mtu
#define btr_sco_mtu	btru.btri.btri_sco_mtu
#define btr_link_policy btru.btri.btri_link_policy
#define btr_packet_type btru.btri.btri_packet_type
#define btr_stats	btru.btrs

/* btr_flags */
#define BTF_UP			(1<<0)	/* unit is up */
#define BTF_RUNNING		(1<<1)	/* unit is running */
#define BTF_XMIT_CMD		(1<<2)	/* transmitting CMD packets */
#define BTF_XMIT_ACL		(1<<3)	/* transmitting ACL packets */
#define BTF_XMIT_SCO		(1<<4)	/* transmitting SCO packets */
#define BTF_INIT_BDADDR		(1<<5)	/* waiting for bdaddr */
#define BTF_INIT_BUFFER_SIZE	(1<<6)	/* waiting for buffer size */
#define BTF_INIT_FEATURES	(1<<7)	/* waiting for features */

struct bt_stats {
	uint32_t	err_tx;
	uint32_t	err_rx;
	uint32_t	cmd_tx;
	uint32_t	evt_rx;
	uint32_t	acl_tx;
	uint32_t	acl_rx;
	uint32_t	sco_tx;
	uint32_t	sco_rx;
	uint32_t	byte_tx;
	uint32_t	byte_rx;
};

SIOCGBTINFO: Get Bluetooth device info. Given the device name, fill in the btreq structure including the address field for use with socket addressing as above.
SIOCGBTINFOA: Get Bluetooth device info from address. Given the device address, fill in the btreq structure including the name field.
SIOCNBTINFO: Next Bluetooth device info. If the name field is empty, the first device will be returned. Otherwise, the next device will be returned. This can be used to cycle through all devices in the system.
SIOCSBTFLAGS: Set Bluetooth device flags. Not all flags can be set.
SIOCSBTPOLICY: Set Bluetooth device link policy. Link policy bits are defined in ⟨netbt/hci.h⟩, though bits can only be set if the device supports it.
SIOCSBTPTYPE: Set Bluetooth device packet types. Only packet types that the device supports can be set.
SIOCGBTSTATS: Read device statistics.
SIOCZBTSTATS: Read device statistics, and zero them.

Only the super-user may change device configurations.

HISTORY

The Bluetooth protocol stack was written for NetBSD 4.0 by Iain Hibbert under the sponsorship of Itronix, Inc. and ported to OpenBSD 4.2 by Uwe Stuehler ⟨uwe@openbsd.org⟩.

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