Accepting L2CAP Connections in a Bluetooth Profile Driver

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An L2CAP server profile driver responds to incoming Logical Link Control and Adaptation Protocol (L2CAP) connection requests from remote devices. For example, an L2CAP server profile driver for a PDA would respond to an incoming connection request from the PDA.

To Receive Incoming L2CAP Connection Requests

  1. To receive incoming L2CAP connection requests fromanyremote device for a particular PSM, profile drivers should first build and send a BRB_L2CA_REGISTER_SERVER request, specifying NULL in the BtAddress member and 0 in the Psm member of the request's _BRB_L2CA_REGISTER_SERVER structure. Profile drivers must also register an L2CAP Callback Function with the Bluetooth driver stack when sending the BRB_L2CA_REGISTER_SERVER request. This enables the Bluetooth driver stack to notify the profile driver of incoming L2CAP connection requests.

    Then, profile drivers should build and send a BRB_REGISTER_PSM request so the Bluetooth driver stack will accept connections from the PSM registered by the request. Otherwise, the Bluetooth driver stack rejects all connection requests that have unknown (unregistered) connection requests. For more information about PSMs, see the _BRB_PSM structure.

  2. To receive incoming L2CAP connection requests from aspecificremote device/PSM pair, profile drivers should build and send a BRB_L2CA_REGISTER_SERVER request, specifying the remote device's address in the BtAddress member, and PSM in the Psm member, of the request's accompanying _BRB_L2CA_REGISTER_SERVER structure. Profile drivers must also register an L2CAP Callback Function with the Bluetooth driver stack when sending the BRB_L2CA_REGISTER_SERVER request. This enables the Bluetooth driver stack to notify the profile driver of incoming L2CAP connection requests.

  3. The profile driver should issue an IOCTL_BTH_SDP_SUBMIT_RECORD. The profile driver can then register an SDP record that describes the service that the profile driver supports, so that remote systems can discover the new service by using SDP.

  4. When the Bluetooth driver stack receives an incoming L2CAP connection request from a remote device, the Bluetooth driver stack calls the L2CAP Callback Function registered earlier by the profile driver. The Bluetooth driver stack passes the value IndicationRemoteConnect to the Indication parameter of the callback function.

  5. To respond to incoming connection requests, profile drivers should build and send a BRB_L2CA_OPEN_CHANNEL_RESPONSE request. The server profile driver uses the value passed from the Bluetooth driver stack in the Parameters parameter of the callback function to negotiate the connection settings with the remote device. Based on the value of the Response member of the _BRB_L2CA_OPEN_CHANNEL structure passed with this request, the server profile driver accepts or rejects the connection request.

  6. If the server profile driver accepts the connection, the Bluetooth driver stack can then call the L2CAP Callback Function as specified in the Callback member of the _BRB_L2CA_OPEN_CHANNEL structure. The Bluetooth driver stack uses this function to notify the server profile driver of any changes to the L2CAP connection.

Note  

  • A single profile driver can register to receive incoming L2CAP connection requests from multiple, different remote device/PSM pairs by building and sending multiple BRB_L2CA_REGISTER_SERVER requests to register multiple L2CAP servers, specifying unique remote device address and PSM pairs in the BtAddress and Psm members of the requests.

  • A single profile driver can register to receive incoming L2CAP connection requests from any remote device for a particular PSM, as well as receive incoming L2CAP connection requests from multiple, different remote device/PSM pairs, by first registering to receive incoming L2CAP connection requests from any remote device for a particular PSM, and then registering to receive incoming L2CAP connection requests from a specific remote device/PSM pair as long as the particular PSM registered in the first step is not registered again.

  • Multiple profile drivers cannot register to receive incoming L2CAP connection requests from any remote device for the same PSM. The Bluetooth driver stack only permits one profile driver to receive incoming L2CAP connection requests from any remote device for a particular PSM.

 

After the profile driver accepts a connection request, it can use other BRBs to send and receive data over the newly established L2CAP connection.

To stop receiving notifications of remote device L2CAP connection attempts, profile drivers should build and send a BRB_L2CA_UNREGISTER_SERVER request to unregister a server when the profile driver processes IRP_MN_REMOVE_DEVICE Plug and Play remove notifications.

For more information about notifications and callback functions, see Supporting Bluetooth Event Notifications.

 

 

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