Manual Pages  — SNMP_NETGRAPH

snmp_netgraph, snmp_node, snmp_nodename, ng_cookie_f, ng_hook_f, ng_register_cookie, ng_unregister_cookie, ng_register_hook, ng_unregister_hook, ng_unregister_module, ng_output, ng_output_node, ng_output_id, ng_dialog, ng_dialog_node, ng_dialog_id, ng_send_data, ng_mkpeer_id, ng_connect_node, ng_connect_id, ng_connect2_id, ng_connect2_tee_id, ng_rmhook, ng_rmhook_id, ng_rmhook_tee_id, ng_shutdown_id, ng_next_node_id, ng_node_id, ng_node_id_node, ng_node_name, ng_node_type, ng_peer_hook_id – netgraph module for snmpd

LIBRARY SYNOPSIS DESCRIPTION SENDING AND RECEIVING MESSAGES AND DATA ASYNCHRONOUS CONTROL AND DATA MESSAGES FINDING NODES AND NODE CHARACTERISTICS CHANGING THE GRAPH FILES SEE ALSO AUTHORS

(begemotSnmpdModulePath."netgraph" = /usr/lib/snmp_netgraph.so)

#include <bsnmp/snmpmod.h>

#include <bsnmp/snmp_netgraph.h>

extern ng_ID_t snmp_node;
extern u_char *snmp_nodename;

typedef void
ng_cookie_f(const struct ng_mesg *mesg, const char *path, ng_ID_t id, void *uarg);

typedef void
ng_hook_f(const char *hook, const u_char *mesg, size_t len, void *uarg);

void *
ng_register_cookie(const struct lmodule *mod, uint32_t cookie, ng_ID_t id, ng_cookie_f *func, void *uarg);

void
ng_unregister_cookie(void *reg);

void *
ng_register_hook(const struct lmodule *mod, const char *hook, ng_hook_f *func, void *uarg);

void
ng_unregister_hook(void *reg);

void
ng_unregister_module(const struct lmodule *mod);

int
ng_output(const char *path, u_int cookie, u_int opcode, const void *arg, size_t arglen);

int
ng_output_node(const char *node, u_int cookie, u_int opcode, const void *arg, size_t arglen);

int
ng_output_id(ng_ID_t node, u_int cookie, u_int opcode, const void *arg, size_t arglen);

struct ng_mesg *
ng_dialog(const char *path, u_int cookie, u_int opcode, const void *arg, size_t arglen);

struct ng_mesg *
ng_dialog_node(const char *node, u_int cookie, u_int opcode, const void *arg, size_t arglen);

struct ng_mesg *
ng_dialog_id(ng_ID_t id, u_int cookie, u_int opcode, const void *arg, size_t arglen);

int
ng_send_data(const char *hook, const void *sndbuf, size_t sndlen);

ng_ID_t
ng_mkpeer_id(ng_ID_t id, const char *name, const char *type, const char *hook, const char *peerhook);

int
ng_connect_node(const char *node, const char *ourhook, const char *peerhook);

int
ng_connect_id(ng_ID_t id, const char *ourhook, const char *peerhook);

int
ng_connect2_id(ng_ID_t id, ng_ID_t peer, const char *ourhook, const char *peerhook);

int
ng_connect2_tee_id(ng_ID_t id, ng_ID_t peer, const char *ourhook, const char *peerhook);

int
ng_rmhook(const char *ourhook);

int
ng_rmhook_id(ng_ID_t id, const char *hook);

int
ng_rmhook_tee_id(ng_ID_t id, const char *hook);

int
ng_shutdown_id(ng_ID_t id);

ng_ID_t
ng_next_node_id(ng_ID_t node, const char *type, const char *hook);

ng_ID_t
ng_node_id(const char *path);

ng_ID_t
ng_node_id_node(const char *node);

ng_ID_t
ng_node_name(ng_ID_t id, char *name);

ng_ID_t
ng_node_type(ng_ID_t id, char *type);

int
ng_peer_hook_id(ng_ID_t id, const char *hook, char *peerhook);

The snmp_netgraph module implements a number of tables and scalars that enable remote access to the netgraph subsystem. It also exports a number of global variables and functions, that allow other modules to easily use the netgraph system.

If upon start up of the module the variable begemotNgControlNodeName is not empty the module opens a netgraph socket and names that socket node. If the variable is empty, the socket is created, as soon as the variable is written with a non-empty name. The socket can be closed by writing an empty string to the variable. The socket itself and its name are available in snmp_node and snmp_nodename.

A module can register functions to asynchronously receive control and data message.

The function ng_register_cookie() registers a control message receive function. If a control message is received, that is not consumed by the dialog functions, the list of registered control message receive functions is scanned. If the cookie in the received message is the same as the cookie argument to the ng_register_cookie() call and the id argument to the ng_register_cookie() call was either 0 or equals the node id which sent the control message, the handler function func is called with a pointer to the received message, the hook on which the message was received (or NULL if it was received not on a hook), the id of the sender's node and the uarg argument of the registration call. The handler function should not modify the contents of the message, because more than one function may be registered to the same cookie and node id.

A control message registration can be undone by calling ng_unregister_cookie() with the return value of the registration call. If an error occurs while registering, ng_register_cookie() returns NULL.

A module can call ng_register_hook() to register a callback for data messages on one of the snmp_node's hooks. If a data message is received on that hook, the callback function func is called with the hook name, a pointer to the data message, the size of the message and the argument uarg to the registration function. The message should be treated as read-only. A data message registration can be undone by calling ng_unregister_hook() with the return value of the registration call. If an error occurs while registering, ng_register_hook() returns NULL.

The function ng_unregister_module() removes all control and data registrations for that module.

A number of functions can be used to create or destroy nodes and hooks.

The function ng_mkpeer_id() creates a new node of type type whose hook peerhook will be connected to hook of node id. If name is not NULL the new node is named with this name. The function returns The node id of the new node or 0 if an error happens.

The functions ng_connect_node() and ng_connect_id() make a new hook connecting ourhook of the modules socket node snmp_node to peerhook of the node identified by id id or name node. The functions return 0 on success or -1 otherwise.

The function ng_connect2_id() connects hook ourhook of the node with id id to hook peerhook of the node with id peer. The functions return 0 on success or -1 otherwise. The function ng_connect2_tee_id() does the same as ng_connect2_id() except, that it puts an unnamed tee node between the two nodes.

The function ng_rmhook() removes hook hook on the module's snmp_node. The function ng_rmhook_id() removes hook hook on the node with id id. The function ng_rmhook_tee_id() additionally shuts down all tee nodes between the node and the first non-tee peer.

The function ng_shutdown_id() destroys the given node.

/usr/share/bsnmp/defs/netgraph_tree.def
	The description of the MIB tree implemented by snmp_netgraph.
/usr/share/bsnmp/mibs/BEGEMOT-NETGRAPH.txt
	This is the MIB that is implemented by this module.

Hartmut Brandt <Mt harti@FreeBSD.org>