libnl 1.1
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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. | |
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() | |
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 |
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 ------------------+---------------------- 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);
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 |
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 75 of file handlers.h.
{ /** Default handlers (quiet) */ NL_CB_DEFAULT, /** Verbose default handlers (error messages printed) */ NL_CB_VERBOSE, /** Debug handlers for debugging */ NL_CB_DEBUG, /** Customized handler specified by the user */ NL_CB_CUSTOM, __NL_CB_KIND_MAX, };
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.
{ /** Message is valid */ NL_CB_VALID, /** Last message in a series of multi part messages received */ NL_CB_FINISH, /** Report received that data was lost */ NL_CB_OVERRUN, /** Message wants to be skipped */ NL_CB_SKIPPED, /** Message is an acknowledge */ NL_CB_ACK, /** Called for every message received */ NL_CB_MSG_IN, /** Called for every message sent out except for nl_sendto() */ NL_CB_MSG_OUT, /** Message is malformed and invalid */ NL_CB_INVALID, /** Called instead of internal sequence number checking */ NL_CB_SEQ_CHECK, /** Sending of an acknowledge message has been requested */ NL_CB_SEND_ACK, __NL_CB_TYPE_MAX, };
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().
{ struct nl_cb *cb; cb = nl_cb_alloc(NL_CB_DEFAULT); if (!cb) return NULL; memcpy(cb, orig, sizeof(*orig)); cb->cb_refcnt = 1; return cb; }
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().
{ if (type < 0 || type > NL_CB_TYPE_MAX) return nl_error(ERANGE, "Callback type out of range"); if (kind < 0 || kind > NL_CB_KIND_MAX) return nl_error(ERANGE, "Callback kind out of range"); if (kind == NL_CB_CUSTOM) { cb->cb_set[type] = func; cb->cb_args[type] = arg; } else { cb->cb_set[type] = cb_def[type][kind]; cb->cb_args[type] = arg; } return 0; }
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 i, err; for (i = 0; i <= NL_CB_TYPE_MAX; i++) { err = nl_cb_set(cb, i, kind, func, arg); if (err < 0) return err; } return 0; }
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().
{ if (kind < 0 || kind > NL_CB_KIND_MAX) return nl_error(ERANGE, "Callback kind out of range"); if (kind == NL_CB_CUSTOM) { cb->cb_err = func; cb->cb_err_arg = arg; } else { cb->cb_err = cb_err_def[kind]; cb->cb_err_arg = arg; } return 0; }
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.
{ cb->cb_recvmsgs_ow = func; }
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.
{ cb->cb_recv_ow = func; }
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.
{ cb->cb_send_ow = func; }