/** @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 #include #include /* * 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); }