NO_SUCH_INSTANCE exception not being caught in v2c - snmp++

[Pallavi Mahajan]

Hi Frank,

How do we check for this exception syntax? I had a look at all the sample pgms, and could not find any such exception handling example.

Regards,
Pallavi


Frank Fock wrote:

> Hi Pallavi,
>
> As you mentioned in your subject, with SNMPv2c or SNMPv3
> there will be no error status set if you request an
> object that does not exist. Instead, an exception syntax
> is returned. Thus, you will have to check the syntax of
> the object for noSuchInstance, noSuchObject, and endOfMibView
> exceptions.
>
> Best regards,
> Frank Fock
>
> Pallavi Mahajan wrote:
> > Hi,
> >
> > Attached is a simple snmpGet program using snmp++, which tries to fetch the value of an OID.
> > In case I enter a wrong OID, no error is returned, instead the value returned is "".
> >
> > If I do the same by changing the version to v1, a proper error is returned in case of wrong OID.
> >
> > For example: in the program attached which uses v2c:
> > If I enter 1.3.6.1.2.1.1.5 (sysName) as the OID, I should get a proper error; whereas i dont get any error, but get a value of "".
> > If I enter 1.3.6.1.2.1.1.5.0 (sysName.0) as the OID, I get the proper sysName value.
> >
> > Please let me know if this is a known bug, or is there something wrong in our handling.
> >
> > Regards,
> > Pallavi
> >
> >
> > ------------------------------------------------------------------------
> >
> > #include <iostream.h>
> > #include <snmp_pp.h>
> >
> > #define SYSNAME_OID "1.3.6.1.2.1.1.5.0"
> >
> > main()
> > {
> >       int status;
> >       Snmp snmp(status);
> >       if (status != SNMP_CLASS_SUCCESS)
> >       {
> >               cout << "ERROR in initializing:: " << snmp.error_msg(status) << endl;
> >               return 0;
> >       }
> >
> >       char ip[200];
> >       cout << "Enter IP of the machine to be managed: ";
> >       cin >> ip;
> >
> >       int port;
> >       cout << "Enter port: ";
> >       cin >> port;
> >
> >       UdpAddress address(ip);
> >       address.set_port(port);
> >       CTarget ctarget( address);
> >       //CTarget ctarget( (IpAddress)ip);
> >       ctarget.set_version(version2c);
> >
> >       char sysname_oid[100];
> >       cout << "enter oid: (1 for sysname) ";
> >       cin >> sysname_oid;
> >
> >       if (strcmp(sysname_oid, "1") == 0)
> >               strcpy(sysname_oid, SYSNAME_OID);
> >
> >       Pdu pdu;
> >       Vb vb(sysname_oid);
> >       pdu += vb;
> >
> >       if ( (status = snmp.get(pdu, ctarget))  != SNMP_CLASS_SUCCESS )
> >       {
> >               cout << "error #: " << status << endl;
> >               cout << "ERROR in get..:: " << snmp.error_msg(status) << endl;
> >               return 0;
> >       }
> >       else
> >       {
> >               pdu.get_vb(vb, 0);
> >               if (strcmp(vb.get_printable_value(), ""))
> >                       cout << "Value = " << vb.get_printable_value() << endl;
> >               else
> >                       cout << "error.." << endl;
> >       }
> >
> >       return 1;
> > }