These functions are used to manage node lists within the software 802.11 stack. These lists are typically used for implementing host-mode AP functionality, or providing signal quality information about neighbouring nodes.
The ieee80211_node_attach function is called from ieee80211_ifattach(9) to initialize node database management callbacks for the interface ifp (specifically for memory allocation, node copying and node signal inspection). These functions may be overridden in special circumstances, as long as this is done after calling ieee80211_ifattach(9) and prior to any other call which may allocate a node.
The ieee80211_node_lateattach function initialises the ic_bss node element of the interface ifp during ieee80211_media_init(9). This late attachment is to account for certain special cases described under ieee80211_node_attach.
The ieee80211_node_detach function destroys all node database state associated with the interface ifp, and is usually called during device detach.
The ieee80211_begin_scan function initialises the node database in preparation of an active scan for an access point on the interface ifp. The scan begins on the next radio channel by calling ieee80211_next_scan internally. The actual scanning for an access point is not automated; the device driver itself only handles setting the radio frequency of the card and stepping through the channels.
The ieee80211_next_scan function is used to inform the ieee80211(9) layer that the interface ifp is now scanning for an access point on the next radio channel. A device driver is expected to first call ieee80211_begin_scan, to initialize the node database, then set the radio channel on the device; then, after a certain time has elapsed (200ms for example), call ieee80211_next_scan to move to the next channel. Typically, a callout is used to automate this process; see callout_init(9) for more information on how to use callouts.
The ieee80211_create_ibss function sets up the net80211-specific portion of an interfaces softc, ic, for use in IBSS mode.
The ieee80211_end_scan function is called by ieee80211_next_scan when the state machine has peformed a full cycle of scanning on all available radio channels. Internally, ieee80211_end_scan will inspect the node cache associated with the interface ifp for suitable access points found during scanning, and associate with one, should the parameters of the node match those of the configuration requested from userland.
The ieee80211_alloc_node function allocates an instance of
.Vt "struct ieee80211_node" for a node having the MAC address macaddr, and associates it with the interface ic. If the allocation is successful, the node structure is initialised by ieee80211_setup_node; otherwise, NULL is returned.
The ieee80211_dup_bss function is similar to ieee80211_alloc_node, but is instead used to create a node database entry for the BSSID macaddr associated with the interface ic. If the allocation is successful, the node structure is initialised by ieee80211_setup_node; otherwise, NULL is returned.
The ieee80211_find_node function will iterate through the node list associated with the interface ic, searching for a node entry which matches macaddr. If the entry is found, its reference count is incremented, and a pointer to the node is returned; otherwise, NULL will be returned.
The ieee80211_lookup_node function is similar to ieee80211_find_node, with an additional argument chan which is used to specify a channel for the match. If the entry is found, its reference count is incremented, and a pointer to the node is returned; otherwise, NULL will be returned.
The ieee80211_free_node function will remove the node ni from the node database entries associated with the interface ic, and free any memory associated with the node. This private method can be overridden in ieee80211_node_attach.
The ieee80211_free_allnodes function will iterate through the node list calling ieee80211_free_node for all nodes associated with the interface ic.
The ieee80211_timeout_nodes checks if the inactivity timer of each node associated with the interface ic has exceeded the pre-defined constant IEEE80211_INACT_MAX. If so, then the node is freed, after sending a deauthentication message.
The ieee80211_iterate_nodes function will call the user-defined callback function f for all nodes in the node database associated with the interface ic. The callback is invoked with the with the user-supplied value arg and a pointer to the current node.