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Packet Routing

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The extension layer can choose to listen to all or selected type of events. For example, if the stack wants to only accept connections from one device, it issues BTH_CONTROL_ROUTE_BY_ADDR and provides a single pointer to the Bluetooth device address (*pba). If it is prepared to accept only SCO (synchronous connection-oriented) connections, it provides appropriate link type (link_type) and BTH_CONTROL_ROUTE_BY_LINKTYPE. The same process applies to the class of the device.

To set the routing option, you need to pass the second flag in the uiControl argument when calling HCI_EstablishDeviceContext. The following six options are available.

BTH_CONTROL_ROUTE_ALL

This option is typically reserved for the default handler such as the L2CAP stack. Only one stack can register to accept all the notifications. A notification is passed up to this stack if there are no other stacks registered for this event.

BTH_CONTROL_DEVICEONLY

Use this option to route all local device control packets here. This is used for local device control, that is, place a device into a particular operating mode, one can register for this access, use this callback to program the device, and then deregister. Only one client at a time is allowed. This option is typically used for management layers that do not accept incoming connections at all. There may be more than one of these.

BTH_CONTROL_ROUTE_SECURITY

Use this option to route all security events up this stack including PIN requests. This is used to implement the security manager. With this option, link key/PIN requests for all connections will be forwarded to this stack layer. Only one stack is allowed to be handled for security events.

BTH_CONTROL_ROUTE_BY_ADDR

This option routes all callbacks associated with a particular device up this stack. Only one client is allowed for each BD_ADDR structure.

BTH_CONTROL_ROUTE_BY_COD

Use this option to route connection requests associated with this COD up this stack. Only one client is allowed for each COD.

BTH_CONTROL_ROUTE_BY_LINKTYPE

Use this option to route connection requests associated with this link type up this stack. This is used to implement SCO connections. A sample SCO connection scenario includes registering for a particular Bluetooth device, processing all SCO data packets here, and then returning all L2CAP packets to the L2CAP layer.

See Also

Establishing Connections through HCI | Enhancing the Bluetooth Stack

Last updated on Wednesday, April 13, 2005

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