Question

My following code is not working as I want to get the description of a node using the Net-Snmp library.

#include "net-snmp/net-snmp-config.h"
#include "net-snmp/net-snmp-includes.h"

void  print_s(struct tree *);

    int main(int argc, char ** argv)
    {
        char buff[100]; 
        struct tree *node=NULL;

        init_mib();
        node=read_all_mibs();
        if( node == NULL )
        {
        exit(2);
        }
        print_s(node);  
    } 


void  print_s(struct tree *tree)
    {       
    struct tree    *tp; 

    for (tp = tree->child_list; tp; tp = tp->next_peer) 
    {
printf("%s:%s\n",tp->label,tp->description); 
    }
    for (tp = tree->child_list; tp; tp = tp->next_peer) 
          {           
              if (tp->child_list)
                  print_s(tp);
          }           

    }




    o/p-
org:(null)
dod:(null)
internet:(null)
snmpV2:(null)
security:(null)
private:(null)
experimental:(null)
mgmt:(null)
directory:(null)
snmpModules:(null)
snmpProxys:(null)
snmpDomains:(null)
snmpMIB:(null)
snmpFrameworkMIB:(null)
.........
........

I am getting the null for all the nodes,

Kindly tell me why I am not able to get the description of nodes as it is available .when I am using the command line option as follow

snmptranslate -On -Td 1.3.6.1.6.3.10

Result
-----------
 .1.3.6.1.6.3.10
snmpFrameworkMIB MODULE-IDENTITY
  -- FROM       SNMP-FRAMEWORK-MIB
  DESCRIPTION   "The SNMP Management Architecture MIB

                     Copyright (C) The Internet Society (2002). This
                     version of this MIB module is part of RFC 3411;
                     see the RFC itself for full legal notices.
                    "
::= { iso(1) org(3) dod(6) internet(1) snmpV2(6) snmpModules(3) 10 }

1.3.6.1.6.3.10 is the oid of the snmpFrameworkMIB but you can see above the node in my program got null as its description.

Can any one know what is the problem here.

Answer 1

By default the net-snmp MIB parser does not turn on DESCRIPTION string storage
in particular because it takes more memory.

To print description call:

snmp_set_save_descriptions(1);

before calling init_snmp() to force saving of the DESCRIPTION clauses.

The function void snmp_set_save_descriptions(int);

declared in include/net-snmp/mib_api.h and defined in snmplib/ucd_compat.c.

Definition:

void
snmp_set_save_descriptions(int save)
{
   netsnmp_ds_set_boolean(NETSNMP_DS_LIBRARY_ID, 
                          NETSNMP_DS_LIB_SAVE_MIB_DESCRS, save);
}

EDIT:

call snmp_set_save_descriptions(1); before init_snmp() Also ..init_snmp() calls netsnmp_init_mib() So not need to call netsnmp_init_mib() explicitly if one is calling init_snmp()