bionic (3) snmpstructfiller.3.gz

NAME

       snmpstrucfiller - snmpkit functions for taking making snmp requests based upon a structure.

SYNOPSIS

       #include <snmpkit.h>

       SNMPSTRUCTFILLER *new_snmpstructfiller(SNMPSESSION *session);
       void delete_snmpstructfiller(SNMPSTRUCTFILLER *doomed);
       void snmpstructfiller_append(SNMPSTRUCTFILLER *sf, const char *oidstr,Tags tag, unsigned int offset);
       void snmpstructfiller_remove(SNMPSTRUCTFILLER *sf,const char *oidstr);
       void *snmpstructfiller_get(SNMPSTRUCTFILLER *sf,void *tobefilled);
       void *snmpstructfiller_get_next(SNMPSTRUCTFILLER *sf, void *tobefilled);

DESCRIPTION

       A snmpstructfiller is an opaque data structure used fill C structures with data from the snmp requests.

       The  SNMP  protocol  is  designed in a way where there is significant overhead in process of encoding and
       exchanging a packet. Therefore it is very inefficient and time consuming to exchange  many  variables  in
       individual  request  packets. The way around this is to bulk up a bunch of snmp requests into one packet.
       Since you are most frequently fetching information which is related the snmp structure filler is designed
       to  associate the snmp objects and data types with the offsets into the structure. That way when you do a
       get or a get_next you will get back a completely filled in structure.

       The new_snmpstructfiller() function creates new structfiller. You  will  need  one  of  these  for  every
       different  set  of  objects that you want to fetch. It starts out not having any requests associated with
       it. To add requests to this structure use the snmpstructfiller_append()  function.  To  actually  do  the
       request, use the snmpstructfiller_get() or the snmpstructfiller_get_next() functions.

       The  delete_snmpstructfiller()  function  is the opposite of the new function. It frees all the resources
       used by  the structfiller structure.

       The snmpstructfiller_append() function appends a new snmp object to the structure filler. It requires the
       oidstring.   This  snmp library doesn't bother attempting to read MIBS.  You must specify the snmp object
       in dotted decimal notation. For example, system.sysDesc is "1.3.6.1.2.1.1.1.0". This means that you  must
       look  up  the objects ID's before hand. This sounds like a lot of work but I have found that when writing
       an application it is really not that much of a problem. The tag is the type of data that  the  object  is
       supposed  to  have  as defined in the MIB and cooresponds directly to the space used in the structure you
       are filling. The tag can be one of the following:

       INT_TAG long

       STRING_TAG char*

       IPADDR_TAG unsigned long
              You get the IPADDR back in binary format. You must translate it byte for byte to get an IPADDR  in
              the format that is usually expected.

       COUNTER_TAG long
              This  could  concievably  be  an unsigned long but enough implementations of MIBS are fouled up in
              such that even though the mib specifies a counter, the device returns an integer. That it is  best
              to store this number in an integer rather than an unsigned..

       TIME_TICK_TAG long

       The  final  parameter  is  offset  into the structure. For example if you have a structure and a variable
       like:
          struct info {
              char *descr; char *contact;
          } foo;

       Then the offset of descr would be (char*)&(foo.descr)-(char*)&foo and the  offset  of  contact  would  be
       (char*)&(foo.contact)-(char*)&foo  I  know  that  this  is a very bad way of doing things and I intend to
       change it in the future. Probably what I will do is change this to a function pointer which  when  called
       takes  the pointer to the structure that it is supposed to insert the data in as well as the value of the
       data and it will insert it into the data into the structure.

AUTHOR

       Ben Woodard <ben@users.sourceforge.net>

BUGS

       The library can possibly throw different kinds of C++ exceptions that won't be caught by  the  glue  code
       and therefore it can cause your program to crash inexplicably.

       There is no support for SNMP sets.

       There is no support for getting back an OID.

       There is no support for

SEE ALSO

       libsnmpkit(3), snmpsession(3), snmpsock(3), snmptable(3)