![]() You should then create a data structure (of your choosing) to store connection-specific data, and should return this structure by assignment through the void ** handle passed in as the third parameter. In this function, you should determine the unit number associated with the connection so that you can later send data back to the connecting process. When the kernel control receives a connection from a user-space process, the control’s ctl_connect_func callback is called. Each instance of the control will have a different ctlref, and this value can then be used to determine which behavior to use. It might register a second control, available to any process, for gathering statistics. A KEXT may, for example, register a root-only control for configuring the KEXT. It is possible to take advantage of kernel control naming to allow processes to interact with a KEXT in different ways. This reference must be used to unregister the control, and is also passed as an argument to any callbacks when they are called. On successful return, the second parameter, ctlref, will contain a reference to the registered kernel control. If this flag is set, the value of ctl_name will be ignored. If you need to use a registered ID, you must set the CTL_FLAG_REG_ID_UNIT flag in ctl_flags. In that case, the memory referenced by the ctl_id field will be overwritten with the dynamically-generated ID value when ctl_register returns. It is strongly recommended that you use a dynamically-assigned ID. Note: You may use either a registered Creator ID (available from the Apple Developer Creator ID web page at ) or you may use a dynamically-assigned ID. ctl_getoptĬalled when the user client process calls getsockopt on the socket. ctl_setoptĬalled when the user client process calls setsockopt to set the control configuration. ![]() ctl_sendĬalled when the user client process writes data to the socket. ctl_disconnectĬalled when the user client process closes the control socket. ctl_connectĬalled when the client process calls connect on the socket with the ID/unit number of the registered control. A value of 0 indicates that the default size should be used. Size of buffer reserved for receiving messages. Size of buffer reserved for sending messages. Note, however, that if you set CTL_FLAG_REG_SOCK_STREAM, you must connect to the control using SOCK_STREAM instead of SOCK_DGRAM. You can set the CTL_FLAG_PRIVILEGED flag to require that the user have admin privileges to contact the control.įor more TCP-like behavior, the flag CTL_FLAG_REG_SOCK_STREAM may be specified to indicate that the control should be registered for stream connections rather than datagrams. ctl_flagsįlags that affect the behavior of a control. The value is automatically assigned for dynamically-allocated ctl_id values. ctl_idĪ unique 4 byte ID for the control. The structure’s fields are defined as follows: ctl_nameĪ bundle ID string for your control of up to MAX_KCTL_NAME bytes (including the terminating null). Other fields of the kern_ctl_reg structure contain handler functions that you must create to handle various control requests. For dynamically-allocated control IDs, this value is filled in automatically. A control can be registered multiple times with the same ctl_id, but for each instance a different unit number must be used. The final field, ctl_unit, contains a value that is specific to a given control. ![]() The fields ctl_id and ctl_name can be shared across multiple controls. The kern_ctl_reg structure contains three fields that are used to identify the control. Int ctl_register(struct kern_ctl_reg *userctl, The ctl_register function is defined in as follows: In the KEXT’s start function, you must register a kernel control structure using the ctl_register function. Supporting kernel controls in a KEXT is relatively straightforward. This section describes this API at the kernel level and the user space level. The kernel control API is a bidirectional communication mechanism between a user space application and a KEXT. Using the Kernel Control API for KEXT Control In general, the kernel control API is preferred, as it provides bidirectional communication.įor detailed reference documentation on these APIs, see Kernel Framework Reference. It should be used when multiple clients need to know about a given event, and is not intended as a point-to-point communication mechanism. The kernel event ( kern_event) API, which uses the SYSPROTO_EVENT protocol, allows applications and other KEXTs to be notified when certain kernel events occur. The kernel control ( kern_control) API, which uses the SYSPROTO_CONTROL protocol, allows applications to configure and control a KEXT. Important: Network kernel extensions cannot be controlled or programmatically loaded from sandboxed applications.
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