Network Management

Overview
Requesting a defined procedure
Listening to network events
Defining a network management procedure
Signaling a network event
API Reference

Overview 

The Network Management APIs allow applications, as well as network layer code itself, to call defined network routines at any level in the IP stack, or receive notifications on relevant network events. For example, by using these APIs, application code can request a scan be done on a Wi-Fi- or Bluetooth-based network interface, or request notification if a network interface IP address changes.

The Network Management API implementation is designed to save memory by eliminating code at build time for management routines that are not used. Distinct and statically defined APIs for network management procedures are not used. Instead, defined procedure handlers are registered by using a NET_MGMT_REGISTER_REQUEST_HANDLER macro. Procedure requests are done through a single net_mgmt() API that invokes the registered handler for the corresponding request.

The current implementation is experimental and may change and improve in future releases.

Requesting a defined procedure 

All network management requests are of the form net_mgmt(mgmt_request, ...). The mgmt_request parameter is a bit mask that tells which stack layer is targeted, if a net_if object is implied, and the specific management procedure being requested. The available procedure requests depend on what has been implemented in the stack.

To avoid extra cost, all net_mgmt() calls are direct. Though this may change in a future release, it will not affect the users of this function.

Listening to network events 

You can receive notifications on network events by registering a callback function and specifying a set of events used to filter when your callback is invoked. The callback will have to be unique for a pair of layer and code, whereas on the command part it will be a mask of events.

Two functions are available, net_mgmt_add_event_callback() for registering the callback function, and net_mgmt_del_event_callback() for unregistering a callback. A helper function, net_mgmt_init_event_callback(), can be used to ease the initialization of the callback structure.

When an event occurs that matches a callback’s event set, the associated callback function is invoked with the actual event code. This makes it possible for different events to be handled by the same callback function, if desired.

Warning

Event set filtering allows false positives for events that have the same layer and layer code. A callback handler function must check the event code (passed as an argument) against the specific network events it will handle, regardless of how many events were in the set passed to net_mgmt_init_event_callback().

Note that in order to receive events from multiple layers, one must have multiple listeners registered, one for each layer being listened. The callback handler function can be shared between different layer events.

(False positives can occur for events which have the same layer and layer code.)

An example follows.

/*
 * Set of events to handle.
 * See e.g. include/net/net_event.h for some NET_EVENT_xxx values.
 */
#define EVENT_IFACE_SET (NET_EVENT_IF_xxx | NET_EVENT_IF_yyy)
#define EVENT_IPV4_SET (NET_EVENT_IPV4_xxx | NET_EVENT_IPV4_yyy)

struct net_mgmt_event_callback iface_callback;
struct net_mgmt_event_callback ipv4_callback;

void callback_handler(struct net_mgmt_event_callback *cb,
                      uint32_t mgmt_event,
                      struct net_if *iface)
{
        if (mgmt_event == NET_EVENT_IF_xxx) {
                /* Handle NET_EVENT_IF_xxx */
        } else if (mgmt_event == NET_EVENT_IF_yyy) {
                /* Handle NET_EVENT_IF_yyy */
        } else if (mgmt_event == NET_EVENT_IPV4_xxx) {
                /* Handle NET_EVENT_IPV4_xxx */
        } else if (mgmt_event == NET_EVENT_IPV4_yyy) {
                /* Handle NET_EVENT_IPV4_yyy */
        } else {
                /* Spurious (false positive) invocation. */
        }
}

void register_cb(void)
{
        net_mgmt_init_event_callback(&iface_callback, callback_handler,
                                     EVENT_IFACE_SET);
        net_mgmt_init_event_callback(&ipv4_callback, callback_handler,
                                     EVENT_IPV4_SET);
        net_mgmt_add_event_callback(&iface_callback);
        net_mgmt_add_event_callback(&ipv4_callback);
}

See include/net/net_event.h for available generic core events that can be listened to.

Defining a network management procedure 

You can provide additional management procedures specific to your stack implementation by defining a handler and registering it with an associated mgmt_request code.

Management request code are defined in relevant places depending on the targeted layer or eventually, if l2 is the layer, on the technology as well. For instance, all IP layer management request code will be found in the include/net/net_event.h header file. But in case of an L2 technology, let’s say Ethernet, these would be found in include/net/ethernet.h

You define your handler modeled with this signature:

static int your_handler(uint32_t mgmt_event, struct net_if *iface,
                        void *data, size_t len);

and then register it with an associated mgmt_request code:

NET_MGMT_REGISTER_REQUEST_HANDLER(<mgmt_request code>, your_handler);

This new management procedure could then be called by using:

net_mgmt(<mgmt_request code>, ...);

Signaling a network event 

You can signal a specific network event using the net_mgmt_notify() function and provide the network event code. See include/net/net_mgmt.h for details. As for the management request code, event code can be also found on specific L2 technology mgmt headers, for example include/net/ieee802154_mgmt.h would be the right place if 802.15.4 L2 is the technology one wants to listen to events.

API Reference 

group net_mgmt

Network Management.

Defines

net_mgmt(_mgmt_request, _iface, _data, _len)

NET_MGMT_DEFINE_REQUEST_HANDLER(_mgmt_request)

NET_MGMT_REGISTER_REQUEST_HANDLER(_mgmt_request, _func)

Typedefs

typedef int (*net_mgmt_request_handler_t)(uint32_t mgmt_request, struct net_if *iface, void *data, size_t len)

Signature which all Net MGMT request handler need to follow.

Param mgmt_request: The exact request value the handler is being called through
Param iface: A valid pointer on struct net_if if the request is meant to be tight to a network interface. NULL otherwise.
Param data: A valid pointer on a data understood by the handler. NULL otherwise.
Param len: Length in byte of the memory pointed by data.

typedef void (*net_mgmt_event_handler_t)(struct net_mgmt_event_callback *cb, uint32_t mgmt_event, struct net_if *iface)

Define the user’s callback handler function signature.

Param cb: Original struct net_mgmt_event_callback owning this handler.
Param mgmt_event: The network event being notified.
Param iface: A pointer on a struct net_if to which the the event belongs to, if it’s an event on an iface. NULL otherwise.

Functions

static inline void net_mgmt_init_event_callback(struct net_mgmt_event_callback *cb, net_mgmt_event_handler_t handler, uint32_t mgmt_event_mask)

Helper to initialize a struct net_mgmt_event_callback properly.

Parameters

cb – A valid application’s callback structure pointer.
handler – A valid handler function pointer.
mgmt_event_mask – A mask of relevant events for the handler

void net_mgmt_add_event_callback(struct net_mgmt_event_callback *cb)

Add a user callback.

Parameters

cb – A valid pointer on user’s callback to add.

void net_mgmt_del_event_callback(struct net_mgmt_event_callback *cb)

Delete a user callback.

Parameters

cb – A valid pointer on user’s callback to delete.

void net_mgmt_event_notify_with_info(uint32_t mgmt_event, struct net_if *iface, const void *info, size_t length)

Used by the system to notify an event.

Note: info and length are disabled if CONFIG_NET_MGMT_EVENT_INFO is not defined.

Parameters

mgmt_event – The actual network event code to notify
iface – a valid pointer on a struct net_if if only the event is based on an iface. NULL otherwise.
info – a valid pointer on the information you want to pass along with the event. NULL otherwise. Note the data pointed there is normalized by the related event.
length – size of the data pointed by info pointer.

static inline void net_mgmt_event_notify(uint32_t mgmt_event, struct net_if *iface)

int net_mgmt_event_wait(uint32_t mgmt_event_mask, uint32_t *raised_event, struct net_if **iface, const void **info, size_t *info_length, k_timeout_t timeout)

Used to wait synchronously on an event mask.

Parameters

mgmt_event_mask – A mask of relevant events to wait on.
raised_event – a pointer on a uint32_t to get which event from the mask generated the event. Can be NULL if the caller is not interested in that information.
iface – a pointer on a place holder for the iface on which the event has originated from. This is valid if only the event mask has bit NET_MGMT_IFACE_BIT set relevantly, depending on events the caller wants to listen to.
info – a valid pointer if user wants to get the information the event might bring along. NULL otherwise.
info_length – tells how long the info memory area is. Only valid if the info is not NULL.
timeout – A timeout delay. K_FOREVER can be used to wait indefinitely.

Returns

0 on success, a negative error code otherwise. -ETIMEDOUT will be specifically returned if the timeout kick-in instead of an actual event.

int net_mgmt_event_wait_on_iface(struct net_if *iface, uint32_t mgmt_event_mask, uint32_t *raised_event, const void **info, size_t *info_length, k_timeout_t timeout)

Used to wait synchronously on an event mask for a specific iface.

Parameters

iface – a pointer on a valid network interface to listen event to
mgmt_event_mask – A mask of relevant events to wait on. Listened to events should be relevant to iface events and thus have the bit NET_MGMT_IFACE_BIT set.
raised_event – a pointer on a uint32_t to get which event from the mask generated the event. Can be NULL if the caller is not interested in that information.
info – a valid pointer if user wants to get the information the event might bring along. NULL otherwise.
info_length – tells how long the info memory area is. Only valid if the info is not NULL.
timeout – A timeout delay. K_FOREVER can be used to wait indefinitely.

Returns

0 on success, a negative error code otherwise. -ETIMEDOUT will be specifically returned if the timeout kick-in instead of an actual event.

void net_mgmt_event_init(void): Used by the core of the network stack to initialize the network event processing.

struct net_mgmt_event_callback

#include <net_mgmt.h>

Network Management event callback structure Used to register a callback into the network management event part, in order to let the owner of this struct to get network event notification based on given event mask.

Public Members

sys_snode_t node: Meant to be used internally, to insert the callback into a list. So nobody should mess with it.

net_mgmt_event_handler_t handler: Actual callback function being used to notify the owner

struct k_sem *sync_call: Semaphore meant to be used internaly for the synchronous net_mgmt_event_wait() function.

uint32_t event_mask: A mask of network events on which the above handler should be called in case those events come. Note that only the command part is treated as a mask, matching one to several commands. Layer and layer code will be made of an exact match. This means that in order to receive events from multiple layers, one must have multiple listeners registered, one for each layer being listened.

uint32_t raised_event: Internal place holder when a synchronous event wait is successfully unlocked on a event.

union net_mgmt_event_callback.[anonymous] [anonymous]: A mask of network events on which the above handler should be called in case those events come. Such mask can be modified whenever necessary by the owner, and thus will affect the handler being called or not.

Network Management

Overview

Requesting a defined procedure

Listening to network events

Defining a network management procedure

Signaling a network event

API Reference

Overview 

Requesting a defined procedure 

Listening to network events 

Defining a network management procedure 

Signaling a network event 

API Reference 