Callbacks can control the flow of the underlying layer by returning the appropriate error codes:
Action ID | Description -----------------+------------------------------------------------------- NL_OK | Proceed with whatever comes next. NL_SKIP | Skip message currently being processed and continue | with next message. NL_STOP | Stop parsing and discard all remaining messages in | this set of messages.
All callbacks are optional and a default action is performed if no application specific implementation is provided:
Callback ID | Default Return Value ------------------+---------------------- NL_CB_VALID | NL_OK NL_CB_FINISH | NL_STOP NL_CB_OVERRUN | NL_STOP NL_CB_SKIPPED | NL_SKIP NL_CB_ACK | NL_STOP NL_CB_MSG_IN | NL_OK NL_CB_MSG_OUT | NL_OK NL_CB_INVALID | NL_STOP NL_CB_SEQ_CHECK | NL_OK NL_CB_SEND_ACK | NL_OK | Error Callback | NL_STOP
In order to simplify typical usages of the library, different sets of default callback implementations exist:
NL_CB_DEFAULT: No additional actions NL_CB_VERBOSE: Automatically print warning and error messages to a file descriptor as appropriate. This is useful for CLI based applications. NL_CB_DEBUG: Print informal debugging information for each message received. This will result in every message beint sent or received to be printed to the screen in a decoded, human-readable format.
// Allocate a callback set and initialize it to the verbose default set struct nl_cb *cb = nl_cb_alloc(NL_CB_VERBOSE); // Modify the set to call my_func() for all valid messages nl_cb_set(cb, NL_CB_VALID, NL_CB_CUSTOM, my_func, NULL); // Set the error message handler to the verbose default implementation // and direct it to print all errors to the given file descriptor. FILE *file = fopen(...); nl_cb_err(cb, NL_CB_VERBOSE, NULL, file);
Callback Typedefs | |
typedef int(* | nl_recvmsg_msg_cb_t )(struct nl_msg *msg, void *arg) |
nl_recvmsgs() callback for message processing customization | |
typedef int(* | nl_recvmsg_err_cb_t )(struct sockaddr_nl *nla, struct nlmsgerr *nlerr, void *arg) |
nl_recvmsgs() callback for error message processing customization | |
Callback Handle Management | |
struct nl_cb * | nl_cb_alloc (enum nl_cb_kind kind) |
Allocate a new callback handle. | |
struct nl_cb * | nl_cb_clone (struct nl_cb *orig) |
Clone an existing callback handle. | |
struct nl_cb * | nl_cb_get (struct nl_cb *cb) |
void | nl_cb_put (struct nl_cb *cb) |
Callback Setup | |
int | nl_cb_set (struct nl_cb *cb, enum nl_cb_type type, enum nl_cb_kind kind, nl_recvmsg_msg_cb_t func, void *arg) |
Set up a callback. | |
int | nl_cb_set_all (struct nl_cb *cb, enum nl_cb_kind kind, nl_recvmsg_msg_cb_t func, void *arg) |
Set up a all callbacks. | |
int | nl_cb_err (struct nl_cb *cb, enum nl_cb_kind kind, nl_recvmsg_err_cb_t func, void *arg) |
Set up an error callback. | |
Overwriting | |
void | nl_cb_overwrite_recvmsgs (struct nl_cb *cb, int(*func)(struct nl_handle *, struct nl_cb *)) |
Overwrite internal calls to nl_recvmsgs(). | |
void | nl_cb_overwrite_recv (struct nl_cb *cb, int(*func)(struct nl_handle *, struct sockaddr_nl *, unsigned char **, struct ucred **)) |
Overwrite internal calls to nl_recv(). | |
void | nl_cb_overwrite_send (struct nl_cb *cb, int(*func)(struct nl_handle *, struct nl_msg *)) |
Overwrite internal calls to nl_send(). | |
Enumerations | |
enum | nl_cb_action { NL_OK, NL_SKIP, NL_STOP } |
Callback actions. More... | |
enum | nl_cb_kind { NL_CB_DEFAULT, NL_CB_VERBOSE, NL_CB_DEBUG, NL_CB_CUSTOM, __NL_CB_KIND_MAX } |
Callback kinds. More... | |
enum | nl_cb_type { NL_CB_VALID, NL_CB_FINISH, NL_CB_OVERRUN, NL_CB_SKIPPED, NL_CB_ACK, NL_CB_MSG_IN, NL_CB_MSG_OUT, NL_CB_INVALID, NL_CB_SEQ_CHECK, NL_CB_SEND_ACK, __NL_CB_TYPE_MAX } |
Callback types. More... |
typedef int(* nl_recvmsg_msg_cb_t)(struct nl_msg *msg, void *arg) |
msg | netlink message being processed | |
arg | argument passwd on through caller |
Definition at line 40 of file handlers.h.
typedef int(* nl_recvmsg_err_cb_t)(struct sockaddr_nl *nla, struct nlmsgerr *nlerr, void *arg) |
nla | netlink address of the peer | |
nlerr | netlink error message being processed | |
arg | argument passed on through caller |
Definition at line 49 of file handlers.h.
enum nl_cb_action |
NL_OK | Proceed with wathever would come next. |
NL_SKIP | Skip this message. |
NL_STOP | Stop parsing altogether and discard remaining messages. |
Definition at line 58 of file handlers.h.
enum nl_cb_kind |
Definition at line 75 of file handlers.h.
enum nl_cb_type |
NL_CB_VALID | Message is valid. |
NL_CB_FINISH | Last message in a series of multi part messages received. |
NL_CB_OVERRUN | Report received that data was lost. |
NL_CB_SKIPPED | Message wants to be skipped. |
NL_CB_ACK | Message is an acknowledge. |
NL_CB_MSG_IN | Called for every message received. |
NL_CB_MSG_OUT | Called for every message sent out except for nl_sendto(). |
NL_CB_INVALID | Message is malformed and invalid. |
NL_CB_SEQ_CHECK | Called instead of internal sequence number checking. |
NL_CB_SEND_ACK | Sending of an acknowledge message has been requested. |
Definition at line 93 of file handlers.h.
struct nl_cb* nl_cb_alloc | ( | enum nl_cb_kind | kind | ) | [read] |
kind | callback kind to be used for initialization |
Definition at line 255 of file handlers.c.
References nl_cb_err(), and nl_cb_set().
Referenced by nl_cb_clone(), and nl_handle_alloc().
struct nl_cb* nl_cb_clone | ( | struct nl_cb * | orig | ) | [read] |
orig | original callback handle |
Definition at line 285 of file handlers.c.
References nl_cb_alloc(), and NL_CB_DEFAULT.
Referenced by nl_wait_for_ack().
int nl_cb_set | ( | struct nl_cb * | cb, | |
enum nl_cb_type | type, | |||
enum nl_cb_kind | kind, | |||
nl_recvmsg_msg_cb_t | func, | |||
void * | arg | |||
) |
cb | callback set | |
type | callback to modify | |
kind | kind of implementation | |
func | callback function (NL_CB_CUSTOM) | |
arg | argument passed to callback |
Definition at line 337 of file handlers.c.
References NL_CB_CUSTOM.
Referenced by nl_cb_alloc(), nl_cb_set_all(), nl_disable_sequence_check(), nl_socket_modify_cb(), and nl_wait_for_ack().
int nl_cb_set_all | ( | struct nl_cb * | cb, | |
enum nl_cb_kind | kind, | |||
nl_recvmsg_msg_cb_t | func, | |||
void * | arg | |||
) |
cb | callback set | |
kind | kind of callback | |
func | callback function | |
arg | argument to be passwd to callback function |
Definition at line 366 of file handlers.c.
References nl_cb_set().
int nl_cb_err | ( | struct nl_cb * | cb, | |
enum nl_cb_kind | kind, | |||
nl_recvmsg_err_cb_t | func, | |||
void * | arg | |||
) |
cb | callback set | |
kind | kind of callback | |
func | callback function | |
arg | argument to be passed to callback function |
Definition at line 387 of file handlers.c.
References NL_CB_CUSTOM.
Referenced by nl_cb_alloc().
void nl_cb_overwrite_recvmsgs | ( | struct nl_cb * | cb, | |
int(*)(struct nl_handle *, struct nl_cb *) | func | |||
) |
cb | callback set | |
func | replacement callback for nl_recvmsgs() |
Definition at line 416 of file handlers.c.
void nl_cb_overwrite_recv | ( | struct nl_cb * | cb, | |
int(*)(struct nl_handle *, struct sockaddr_nl *, unsigned char **, struct ucred **) | func | |||
) |
cb | callback set | |
func | replacement callback for nl_recv() |
Definition at line 427 of file handlers.c.
void nl_cb_overwrite_send | ( | struct nl_cb * | cb, | |
int(*)(struct nl_handle *, struct nl_msg *) | func | |||
) |
cb | callback set | |
func | replacement callback for nl_send() |
Definition at line 439 of file handlers.c.