Rstory: Created page with "The mib2c [http://net-snmp.git.sourceforge.net/git/gitweb.cgi?p=net-snmp/net-snmp;a=blob_plain;f=local/mib2c.scalar.conf;hb=HEAD scalar configuration file] generates a bare-bones..."

2012-04-18T14:07:14Z

Created page with "The mib2c [http://net-snmp.git.sourceforge.net/git/gitweb.cgi?p=net-snmp/net-snmp;a=blob_plain;f=local/mib2c.scalar.conf;hb=HEAD scalar configuration file] generates a bare-bones..."

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The mib2c [http://net-snmp.git.sourceforge.net/git/gitweb.cgi?p=net-snmp/net-snmp;a=blob_plain;f=local/mib2c.scalar.conf;hb=HEAD scalar configuration file] generates a bare-bones skeleton handler for each scalar object. You must then write code to provide data for the object, handling each mode. For a complete example, see the [http://net-snmp.git.sourceforge.net/git/gitweb.cgi?p=net-snmp/net-snmp;a=blob_plain;f=agent/mibgroup/ip-mib/ip_scalars.c;hb=HEAD IP-MIB scalars implementation] in the source tree. Here is an excerpt:

<pre>
int ipAddressSpinLockValue;

int
handle_ipAddressSpinLock(netsnmp_mib_handler *handler,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests);

/** Initializes the ip module */
void init_ip_scalars(void)
{
static oid ipAddressSpinLock_oid[] = { 1, 3, 6, 1, 2, 1, 4, 33 };

DEBUGMSGTL(("ip_scalar", "Initializing\n"));

netsnmp_register_scalar(netsnmp_create_handler_registration
("ipAddressSpinLock", handle_ipAddressSpinLock,
ipAddressSpinLock_oid,
OID_LENGTH(ipAddressSpinLock_oid),
HANDLER_CAN_RWRITE));

/* Initialize spin lock with random value */
ipAddressSpinLockValue = (int) random();

}

int
handle_ipAddressSpinLock(netsnmp_mib_handler *handler,
netsnmp_handler_registration *reginfo,
netsnmp_agent_request_info *reqinfo,
netsnmp_request_info *requests)
{
long value;

/* We are never called for a GETNEXT if it's registered as a
"instance", as it's "magically" handled for us. */

/* a instance handler also only hands us one request at a time, so
we don't need to loop over a list of requests; we'll only get one. */

switch(reqinfo->mode) {

case MODE_GET:
snmp_set_var_typed_value(requests->requestvb, ASN_INTEGER,
(u_char *)&ipAddressSpinLockValue,
sizeof(ipAddressSpinLockValue));
break;

#ifndef NETSNMP_NO_WRITE_SUPPORT
/*
* SET REQUEST
*
* multiple states in the transaction. See:
* http://www.net-snmp.org/tutorial-5/toolkit/mib_module/set-actions.jpg
*/
case MODE_SET_RESERVE1:
case MODE_SET_RESERVE2:
/* just check the value */
value = *(requests->requestvb->val.integer);
if (value != ipAddressSpinLockValue)
netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_INCONSISTENTVALUE);
break;

case MODE_SET_FREE:
break;

case MODE_SET_ACTION:
/* perform the final spinlock check and increase its value */
value = *(requests->requestvb->val.integer);
if (value != ipAddressSpinLockValue) {
netsnmp_set_request_error(reqinfo, requests, SNMP_ERR_INCONSISTENTVALUE);
} else {
ipAddressSpinLockValue++;
/* and check it for overflow */
if (ipAddressSpinLockValue > 2147483647 || ipAddressSpinLockValue < 0)
ipAddressSpinLockValue = 0;
}
break;

case MODE_SET_COMMIT:
break;

case MODE_SET_UNDO:
break;
#endif /* !NETSNMP_NO_WRITE_SUPPORT */

default:
/* we should never get here, so this is a really bad error */
snmp_log(LOG_ERR, "unknown mode (%d) in handle_ipAddressSpinLock\n", reqinfo->mode );
return SNMP_ERR_GENERR;
}

return SNMP_ERR_NOERROR;
}

</pre>

{{TUT:LIST}}

TUT:mib2c scalar - Revision history

Rstory: Created page with "The mib2c [http://net-snmp.git.sourceforge.net/git/gitweb.cgi?p=net-snmp/net-snmp;a=blob_plain;f=local/mib2c.scalar.conf;hb=HEAD scalar configuration file] generates a bare-bones..."