Re: A question of net-snmp

Dears,

I can get table information that I need by using mib browser, but I find two
questions when I do it.
Q1: If I use the command to get Table A, the agent will ask the inforation A
and information B.
      If I use the command to get Table B, the agent will ask the
inforation B and information C.
      If I use the command to get Table C, the agent will ask the
inforation B and information D.
      ...
      How can I do that let it only gets the needed information?

Q2: If I get a table Information only ONE time, but the agent will ask the
information more than one time.
      Why?
****************************************************************************************************************************
The structure of my system:

User                                            snmp agent
(Net-SNMP-5.4)                               My-Kernel

snmp command  ---- request ---->   receive command and ask the info. ---->
ask ----> get info. and return it
****************************************************************************************************************************
My code that about table:

/* ****************************** Table A ****************************** */
void
initialize_table_fanTable(void)
{
    static oid tableA_oid[] = {1,3,6,1,4,1,3064,2,162,101,105};
    netsnmp_table_data_set    *table_set;
 netsnmp_table_registration_info *table_info;
 netsnmp_iterator_info           *it_info;
    netsnmp_handler_registration    *A_handler;
    /* create the table structure itself */
    table_set = netsnmp_create_table_data_set("tableA");
    /* comment this out or delete if you don't support creation of new rows
*/
    table_set->allow_creation = 1;
    /***************************************************
     * Adding indexes
     */
    netsnmp_table_set_add_indexes(table_set,ASN_OCTET_STR,0);
   netsnmp_table_set_multi_add_default_row(table_set,
                                            COLUMN_NAME, ASN_OCTET_STR, 0,
NULL, 0,
                                            COLUMN_STATUS, ASN_OCTET_STR, 0,
NULL, 0,
                                            0);
 /** create the table registration information structures */
    table_info = SNMP_MALLOC_TYPEDEF(netsnmp_table_registration_info);
    it_info = SNMP_MALLOC_TYPEDEF(netsnmp_iterator_info);
 /** register emsFanTable handler */
    fan_handler = netsnmp_create_handler_registration(
     "tableA",
     A_handler,
     tableA_oid,
     OID_LENGTH(tableA_oid),
     HANDLER_CAN_RONLY);
    if (!fan_handler || !table_info || !it_info) {
        //snmp_log(LOG_ERR, "malloc failed in
initialize_table_emsFanTable");
        return; /** Serious error. */
    }
 /***************************************************
     * Setting up the table's definition
     */
    netsnmp_table_helper_add_indexes(table_info, ASN_OCTET_STR,0);
    /** Define the minimum and maximum accessible columns.  This
        optimizes retrival. */
    table_info->min_column = COLUMN_NAME;
    table_info->max_column = COLUMN_STATUS;
    /** iterator access routines */
    it_info->get_first_data_point = tableA_get_first_data_point;
    it_info->get_next_data_point = tableA_get_next_data_point;
 it_info->free_data_context = tableA_data_free;
 it_info->free_loop_context = tableA_loop_free;
    it_info->free_loop_context_at_end = tableA_loop_free;
    /** tie the two structures together */
    it_info->table_reginfo = table_info;
    /***************************************************
     * registering the table with the master agent
     */
   netsnmp_register_table_iterator(A_handler, it_info);
}
/** handles requests for the emsFanTable table, if anything else needs to be
done */
int
A_handler(
    netsnmp_mib_handler               *handler,
    netsnmp_handler_registration      *reginfo,
    netsnmp_agent_request_info        *reqinfo,
    netsnmp_request_info              *requests) {
    switch (reqinfo->mode)
 {
    case MODE_GET:
  //DEBUGMSGTL(("emsFanTable", "MODE_GET CALLED\n"));
  handle_a_table_get(requests);
  break;
 case MODE_SET_ACTION:
 case MODE_GETNEXT:
 default:
  //
  break;
 }
    return SNMP_ERR_NOERROR;
}
void handle_a_table_get(netsnmp_request_info * requests)
{
 netsnmp_request_info  *request;
    netsnmp_variable_list *requestvb;
    netsnmp_table_request_info *table_info;
 llist_stats_fan* entry = NULL;
 oid subid;
    for (request=requests; request; request=request->next)
 {
     requestvb = request->requestvb;
  entry = (llist_stats_fan*)netsnmp_extract_iterator_context(request);
        if (entry == NULL) {
   continue;
        }
  table_info = netsnmp_extract_table_info(request);
        subid      = table_info->colnum;
  switch (subid)
  {
   case COLUMN_NAME:
    snmp_set_var_typed_value(requestvb, ASN_OCTET_STR, entry->aName,
strlen(entry->aName));
    break;
   case COLUMN_FAN_STATUS:
    snmp_set_var_typed_value(requestvb, ASN_OCTET_STR, entry->aStatus,
strlen(entry->aStatus));
    break;
   default:
    //
    break;
  }
 }
}
netsnmp_variable_list *
tableA_get_first_data_point(void **my_loop_context,
                                  void **my_data_context,
                                  netsnmp_variable_list *put_index_data,
                                  netsnmp_iterator_info *mydata)
{
 static llist_stats * tlist = NULL;
 llist_stats * row;
 int i, curNum=0;
 memset(&snmpReq,0,sizeof(SNMPREQUEST));
 snmpReq.mibtype = SNMPAGENT_REQUEST_IOC_GET_NUM_A;
 getQuantaTableInfo(&snmpReq);
//------------------------------------------------------> call this
command will get info. from kernel
 curNum = snmpReq.integer;
 if(curNum > 0) {
  if(tlist== NULL)
  {
   tlist = SNMP_MALLOC_TYPEDEF(llist_stats);
   if (!tlist)
    return NULL;
   tlist->next = NULL;
  }

  row = tlist;
  for (i=0; i<curNum; i++) {
   memset(&snmpReq,0,sizeof(SNMPREQUEST));
   snmpReq.mibtype = SNMPAGENT_REQUEST_IOC_GET_INFO_A;
   snmpReq.integer = i;
   getQuantaTableInfo(&snmpReq);
   strncpy(row->Name, snmpReq.tableInfo1, sizeof(row->aName));
   strncpy(row->Status, snmpReq.tableInfo2, sizeof(row->aStatus));
   if(i==curNum-1) {
    while(row->next != NULL) {
     llist_stats *nextPtr = row->next;
     while(nextPtr->next != NULL) {
      nextPtr = nextPtr->next;
     }
     free(nextPtr);
     nextPtr = NULL;
    }
    row->next = NULL;
   } else {
    if(row->next == NULL) {
     row->next = SNMP_MALLOC_TYPEDEF(llist_stats);
    }
    row = row->next;
   }
  }
 } else {
  if(tlist != NULL) {
   while(tlist->next != NULL) {
    llist_stats *nextPtr = tlist->next;
    while(nextPtr->next != NULL) {
     nextPtr = nextPtr->next;
    }
    free(nextPtr);
    nextPtr = NULL;
   }
   free(tlist_fan);
   tlist_fan = NULL;
  }
 }

 *my_loop_context = tlist;
 return fanTable_get_next_data_point(my_loop_context,
                                     my_data_context,
                                     put_index_data,
                                     mydata);
}
netsnmp_variable_list *
fanTable_get_next_data_point(void **loop_context,
                                   void **data_context,
                                   netsnmp_variable_list * index,
                                   netsnmp_iterator_info *data)
{
 llist_stats* list = (llist_stats*)*loop_context;
 if(list == NULL)
 {
  return NULL;
 }
 /*set table indexes*/
 snmp_set_var_value(index, (u_char *) list->aName, strlen(list->aName));
 *data_context = (void*)list;
 *loop_context = (void*)list->next;
 return index;
}
void
fanTable_data_free(void *data, netsnmp_iterator_info *iinfo)
{
    //
}
void
fanTable_loop_free(void *loopctx, netsnmp_iterator_info *iinfo)
{
 //
}
******************************************************************************************************************
The table B, C, D,etc are the same as table A.


Best regards,
Bluce

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