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/** @example notification.c
* This example shows how to send a notification from inside the
* agent. In this case we do something really boring to decide
* whether to send a notification or not: we simply sleep for 30
* seconds and send it, then we sleep for 30 more and send it again.
* We do this through the snmp_alarm mechanisms (which are safe to
* use within the agent. Don't use the system alarm() call, it won't
* work properly). Normally, you would probably want to do something
* to test whether or not to send an alarm, based on the type of mib
* module you were creating.
*
* When this module is compiled into the agent (run configure with
* --with-mib-modules="examples/notification") then it should send
* out traps, which when received by the snmptrapd demon will look
* roughly like:
*
* 2002-05-08 08:57:05 localhost.localdomain [udp:127.0.0.1:32865]:
* sysUpTimeInstance = Timeticks: (3803) 0:00:38.03 snmpTrapOID.0 = OID: netSnmpExampleNotification
*
*/
/*
* start be including the appropriate header files
*/
#include <net-snmp/net-snmp-config.h>
#include <net-snmp/net-snmp-includes.h>
#include <net-snmp/agent/net-snmp-agent-includes.h>
/*
* contains prototypes
*/
#include "notification.h"
/*
* our initialization routine
* (to get called, the function name must match init_FILENAME()
*/
void
init_notification(void)
{
DEBUGMSGTL(("example_notification",
"initializing (setting callback alarm)\n"));
snmp_alarm_register(30, /* seconds */
SA_REPEAT, /* repeat (every 30 seconds). */
send_example_notification, /* our callback */
NULL /* no callback data needed */
);
}
/** here we send a SNMP v2 trap (which can be sent through snmpv3 and
* snmpv1 as well) and send it out.
*
* The various "send_trap()" calls allow you to specify traps in different
* formats. And the various "trapsink" directives allow you to specify
* destinations to receive different formats.
* But *all* traps are sent to *all* destinations, regardless of how they
* were specified.
*
*
* I.e. it's
* @verbatim
* ___ trapsink
* /
* send_easy_trap \___ [ Trap ] ____ trap2sink
* ___ [ Generator ]
* send_v2trap / [ ] ----- informsink
* \____
* trapsess
*
* *Not*
* send_easy_trap -------------------> trapsink
* send_v2trap -------------------> trap2sink
* ???? -------------------> informsink
* ???? -------------------> trapsess
* @endverbatim
*/
void
send_example_notification(unsigned int clientreg, void *clientarg)
{
/*
* define the OID for the notification we're going to send
* NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatNotification
*/
oid notification_oid[] =
{ 1, 3, 6, 1, 4, 1, 8072, 2, 3, 0, 1 };
size_t notification_oid_len = OID_LENGTH(notification_oid);
static u_long count = 0;
/*
* In the notification, we have to assign our notification OID to
* the snmpTrapOID.0 object. Here is it's definition.
*/
oid objid_snmptrap[] = { 1, 3, 6, 1, 6, 3, 1, 1, 4, 1, 0 };
size_t objid_snmptrap_len = OID_LENGTH(objid_snmptrap);
/*
* define the OIDs for the varbinds we're going to include
* with the notification -
* NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatRate and
* NET-SNMP-EXAMPLES-MIB::netSnmpExampleHeartbeatName
*/
oid hbeat_rate_oid[] = { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 2, 1, 0 };
size_t hbeat_rate_oid_len = OID_LENGTH(hbeat_rate_oid);
oid hbeat_name_oid[] = { 1, 3, 6, 1, 4, 1, 8072, 2, 3, 2, 2, 0 };
size_t hbeat_name_oid_len = OID_LENGTH(hbeat_name_oid);
/*
* here is where we store the variables to be sent in the trap
*/
netsnmp_variable_list *notification_vars = NULL;
const char *heartbeat_name = "A girl named Maria";
#ifdef RANDOM_HEARTBEAT
int heartbeat_rate = rand() % 60;
#else
int heartbeat_rate = 30;
#endif
DEBUGMSGTL(("example_notification", "defining the trap\n"));
/*
* add in the trap definition object
*/
snmp_varlist_add_variable(¬ification_vars,
/*
* the snmpTrapOID.0 variable
*/
objid_snmptrap, objid_snmptrap_len,
/*
* value type is an OID
*/
ASN_OBJECT_ID,
/*
* value contents is our notification OID
*/
(u_char *) notification_oid,
/*
* size in bytes = oid length * sizeof(oid)
*/
notification_oid_len * sizeof(oid));
/*
* add in the additional objects defined as part of the trap
*/
snmp_varlist_add_variable(¬ification_vars,
hbeat_rate_oid, hbeat_rate_oid_len,
ASN_INTEGER,
(u_char *)&heartbeat_rate,
sizeof(heartbeat_rate));
/*
* if we want to insert additional objects, we do it here
*/
if (heartbeat_rate < 30 ) {
snmp_varlist_add_variable(¬ification_vars,
hbeat_name_oid, hbeat_name_oid_len,
ASN_OCTET_STR,
heartbeat_name, strlen(heartbeat_name));
}
/*
* send the trap out. This will send it to all registered
* receivers (see the "SETTING UP TRAP AND/OR INFORM DESTINATIONS"
* section of the snmpd.conf manual page.
*/
++count;
DEBUGMSGTL(("example_notification", "sending trap %ld\n",count));
send_v2trap(notification_vars);
/*
* free the created notification variable list
*/
DEBUGMSGTL(("example_notification", "cleaning up\n"));
snmp_free_varbind(notification_vars);
}
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