libnl  1.1.4
Enumerations
Callbacks/Customization

Callbacks and overwriting capabilities are provided to take influence in various control flows inside the library. More...

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...
 

Callback Handle Management

struct nl_cb * nl_cb_alloc (enum nl_cb_kind kind)
 Allocate a new callback handle. More...
 
struct nl_cb * nl_cb_clone (struct nl_cb *orig)
 Clone an existing callback handle. More...
 
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. More...
 
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. More...
 
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. More...
 

Overwriting

void nl_cb_overwrite_recvmsgs (struct nl_cb *cb, int(*func)(struct nl_handle *, struct nl_cb *))
 Overwrite internal calls to nl_recvmsgs() More...
 
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() More...
 
void nl_cb_overwrite_send (struct nl_cb *cb, int(*func)(struct nl_handle *, struct nl_msg *))
 Overwrite internal calls to nl_send() More...
 

Callback Typedefs

typedef int(* nl_recvmsg_msg_cb_t )(struct nl_msg *msg, void *arg)
 nl_recvmsgs() callback for message processing customization More...
 
typedef int(* nl_recvmsg_err_cb_t )(struct sockaddr_nl *nla, struct nlmsgerr *nlerr, void *arg)
 nl_recvmsgs() callback for error message processing customization More...
 

Detailed Description

All callbacks are packed together in struct nl_cb which is then attached to a netlink socket or passed on to the respective functions directly.

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
------------------+----------------------
|
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.
1) Setting up a callback set
// 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);

Typedef Documentation

typedef int(* nl_recvmsg_msg_cb_t)(struct nl_msg *msg, void *arg)
Parameters
msgnetlink message being processed
argargument passwd on through caller

Definition at line 41 of file handlers.h.

typedef int(* nl_recvmsg_err_cb_t)(struct sockaddr_nl *nla, struct nlmsgerr *nlerr, void *arg)
Parameters
nlanetlink address of the peer
nlerrnetlink error message being processed
argargument passed on through caller

Definition at line 50 of file handlers.h.

Enumeration Type Documentation

Enumerator
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 59 of file handlers.h.

59  {
60  /** Proceed with wathever would come next */
61  NL_OK,
62  /** Skip this message */
63  NL_SKIP,
64  /** Stop parsing altogether and discard remaining messages */
65  NL_STOP,
66 };
enum nl_cb_kind
Enumerator
NL_CB_DEFAULT 

Default handlers (quiet)

NL_CB_VERBOSE 

Verbose default handlers (error messages printed)

NL_CB_DEBUG 

Debug handlers for debugging.

NL_CB_CUSTOM 

Customized handler specified by the user.

Definition at line 76 of file handlers.h.

76  {
77  /** Default handlers (quiet) */
79  /** Verbose default handlers (error messages printed) */
81  /** Debug handlers for debugging */
83  /** Customized handler specified by the user */
85  __NL_CB_KIND_MAX,
86 };
enum nl_cb_type
Enumerator
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 94 of file handlers.h.

94  {
95  /** Message is valid */
97  /** Last message in a series of multi part messages received */
99  /** Report received that data was lost */
101  /** Message wants to be skipped */
103  /** Message is an acknowledge */
104  NL_CB_ACK,
105  /** Called for every message received */
106  NL_CB_MSG_IN,
107  /** Called for every message sent out except for nl_sendto() */
109  /** Message is malformed and invalid */
111  /** Called instead of internal sequence number checking */
113  /** Sending of an acknowledge message has been requested */
115  __NL_CB_TYPE_MAX,
116 };

Function Documentation

struct nl_cb* nl_cb_alloc ( enum nl_cb_kind  kind)
Parameters
kindcallback kind to be used for initialization
Returns
Newly allocated callback handle or NULL

Definition at line 256 of file handlers.c.

References nl_cb_err(), and nl_cb_set().

Referenced by nl_cb_clone(), and nl_handle_alloc().

257 {
258  int i;
259  struct nl_cb *cb;
260 
261  if (kind < 0 || kind > NL_CB_KIND_MAX)
262  return NULL;
263 
264  cb = calloc(1, sizeof(*cb));
265  if (!cb) {
266  nl_errno(ENOMEM);
267  return NULL;
268  }
269 
270  cb->cb_refcnt = 1;
271 
272  for (i = 0; i <= NL_CB_TYPE_MAX; i++)
273  nl_cb_set(cb, i, kind, NULL, NULL);
274 
275  nl_cb_err(cb, kind, NULL, NULL);
276 
277  return cb;
278 }
struct nl_cb* nl_cb_clone ( struct nl_cb *  orig)
Parameters
origoriginal callback handle
Returns
Newly allocated callback handle being a duplicate of orig or NULL

Definition at line 286 of file handlers.c.

References nl_cb_alloc(), and NL_CB_DEFAULT.

Referenced by nl_wait_for_ack().

287 {
288  struct nl_cb *cb;
289 
291  if (!cb)
292  return NULL;
293 
294  memcpy(cb, orig, sizeof(*orig));
295  cb->cb_refcnt = 1;
296 
297  return cb;
298 }
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 
)
Parameters
cbcallback set
typecallback to modify
kindkind of implementation
funccallback function (NL_CB_CUSTOM)
argargument passed to callback
Returns
0 on success or a negative error code

Definition at line 338 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().

340 {
341  if (type < 0 || type > NL_CB_TYPE_MAX)
342  return nl_error(ERANGE, "Callback type out of range");
343 
344  if (kind < 0 || kind > NL_CB_KIND_MAX)
345  return nl_error(ERANGE, "Callback kind out of range");
346 
347  if (kind == NL_CB_CUSTOM) {
348  cb->cb_set[type] = func;
349  cb->cb_args[type] = arg;
350  } else {
351  cb->cb_set[type] = cb_def[type][kind];
352  cb->cb_args[type] = arg;
353  }
354 
355  return 0;
356 }
int nl_cb_set_all ( struct nl_cb *  cb,
enum nl_cb_kind  kind,
nl_recvmsg_msg_cb_t  func,
void *  arg 
)
Parameters
cbcallback set
kindkind of callback
funccallback function
argargument to be passwd to callback function
Returns
0 on success or a negative error code

Definition at line 367 of file handlers.c.

References nl_cb_set().

369 {
370  int i, err;
371 
372  for (i = 0; i <= NL_CB_TYPE_MAX; i++) {
373  err = nl_cb_set(cb, i, kind, func, arg);
374  if (err < 0)
375  return err;
376  }
377 
378  return 0;
379 }
int nl_cb_err ( struct nl_cb *  cb,
enum nl_cb_kind  kind,
nl_recvmsg_err_cb_t  func,
void *  arg 
)
Parameters
cbcallback set
kindkind of callback
funccallback function
argargument to be passed to callback function

Definition at line 388 of file handlers.c.

References NL_CB_CUSTOM.

Referenced by nl_cb_alloc().

390 {
391  if (kind < 0 || kind > NL_CB_KIND_MAX)
392  return nl_error(ERANGE, "Callback kind out of range");
393 
394  if (kind == NL_CB_CUSTOM) {
395  cb->cb_err = func;
396  cb->cb_err_arg = arg;
397  } else {
398  cb->cb_err = cb_err_def[kind];
399  cb->cb_err_arg = arg;
400  }
401 
402  return 0;
403 }
void nl_cb_overwrite_recvmsgs ( struct nl_cb *  cb,
int(*)(struct nl_handle *, struct nl_cb *)  func 
)
Parameters
cbcallback set
funcreplacement callback for nl_recvmsgs()

Definition at line 417 of file handlers.c.

419 {
420  cb->cb_recvmsgs_ow = func;
421 }
void nl_cb_overwrite_recv ( struct nl_cb *  cb,
int(*)(struct nl_handle *, struct sockaddr_nl *, unsigned char **, struct ucred **)  func 
)
Parameters
cbcallback set
funcreplacement callback for nl_recv()

Definition at line 428 of file handlers.c.

431 {
432  cb->cb_recv_ow = func;
433 }
void nl_cb_overwrite_send ( struct nl_cb *  cb,
int(*)(struct nl_handle *, struct nl_msg *)  func 
)
Parameters
cbcallback set
funcreplacement callback for nl_send()

Definition at line 440 of file handlers.c.

442 {
443  cb->cb_send_ow = func;
444 }