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NetSNMP::agent.3pm

NAME

NetSNMP::agent - Perl extension for the net-snmp agent.

SYNOPSIS

   use NetSNMP::agent;
 
   my $agent = new NetSNMP::agent('Name' => 'my_agent_name');
 
 

DESCRIPTION

This module implements an API set to make a SNMP agent act as a snmp agent, a snmp subagent (using the AgentX subagent protocol) and/or embedded perl-APIs directly within the traditional net-snmp agent demon.

Also see the tutorial about the genaral Net-SNMP C API, which this module implements in a perl-way, and a perl specific tutorial at:

   http://www.net-snmp.org/tutorial-5/toolkit/
 
 

EXAMPLES

Sub-agent example

         use NetSNMP::agent (':all');
         use NetSNMP::ASN qw(ASN_OCTET_STR);
 
         my $value = "hello world";
         sub myhandler {
             my ($handler, $registration_info, $request_info, $requests) = @_;
             my $request;
 
             for($request = $requests; $request; $request = $request->next()) {
                 my $oid = $request->getOID();
                 if ($request_info->getMode() == MODE_GET) {
                     # ... generally, you would calculate value from oid
                     if ($oid == new NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0")) {
                         $request->setValue(ASN_OCTET_STR, $value);
                     }
                 } elsif ($request_info->getMode() == MODE_GETNEXT) {
                     # ... generally, you would calculate value from oid
                     if ($oid < new NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0")) {
                         $request->setOID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0");
                         $request->setValue(ASN_OCTET_STR, $value);
                     }
                 } elsif ($request_info->getMode() == MODE_SET_RESERVE1) {
                     if ($oid != new NetSNMP::OID(".1.3.6.1.4.1.8072.9999.9999.7375.1.0")) {  # do error checking here
                         $request->setError($request_info, SNMP_ERR_NOSUCHNAME);
                     }
                 } elsif ($request_info->getMode() == MODE_SET_ACTION) {
                     # ... (or use the value)
                     $value = $request->getValue();
                 }
             }
 
         }
 
         my $agent = new NetSNMP::agent(
                                 # makes the agent read a my_agent_name.conf file
                                 'Name' => "my_agent_name",
                                 'AgentX' => 1
                                 );
         $agent->register("my_agent_name", ".1.3.6.1.4.1.8072.9999.9999.7375",
                          \&myhandler);
 
         my $running = 1;
         while($running) {
                 $agent->agent_check_and_process(1);
         }
 
         $agent->shutdown();
 
 

Embedded agent example

         # place this in a .pl file, and then in your snmpd.conf file put:
         #    perl do '/path/to/file.pl';
 
         use NetSNMP::agent;
         my $agent;
 
         sub myhandler {
             my ($handler, $registration_info, $request_info, $requests) = @_;
             # ...
         }
 
         $agent = new NetSNMP::agent(
                                 'Name' => 'my_agent_name'
                                 );
 
         $agent->register("my_agent_name", ".1.3.6.1.4.1.8072.9999.9999.7375",
                          \&myhandler);
 
         $agent->main_loop();
 
 

CONSTRUCTOR

     new ( OPTIONS )
         This is the constructor for a new NetSNMP::agent object.
 
     Possible options are:
 
         Name    - Name of the agent (optional, defaults to "perl")
                   (The snmp library will read a NAME.conf snmp
                   configuration file based on this argument.)
         AgentX  - Make us a sub-agent (0 = false, 1 = true)
                   (The Net-SNMP master agent must be running first)
         Ports   - Ports this agent will listen on (EG: "udp:161,tcp:161")
 
     Example:
 
         $agent = new NetSNMP::agent(
                                  'Name' => 'my_agent_name',
                                  'AgentX' => 1
                                  );
 
 

METHODS

     register (NAME, OID, \&handler_routine )
         Registers the callback handler with given OID.
 
         $agent->register();
 
         A return code of 0 indicates no error.
 
     agent_check_and_process ( BLOCKING )
         Run one iteration of the main loop.
 
         BLOCKING - Blocking or non-blocking call. 1 = true, 0 = false.
 
         $agent->agent_check_and_process(1);
 
     main_loop ()
         Runs the agent in a loop. Does not return.
 
     shutdown ()
         Nicely shuts down the agent or sub-agent.
 
         $agent->shutdown();
 
 

HANDLER CALLBACKS

     handler ( HANDLER, REGISTRATION_INFO, REQUEST_INFO, REQUESTS )
 
         The handler is called with the following parameters:
 
         HANDLER                 - FIXME
         REGISTRATION_INFO       - what are the correct meanings of these?
         REQUEST_INFO            -
         REQUESTS                -
 
     Example handler:
 
         sub myhandler {
             my ($handler, $reg_info, $request_info, $requests) = @_;
             # ...
         }
 
 

The handler subroutine will be called when a SNMP request received by the agent for anything below the registered OID. The handler is passed 4 arguments: $handler, $registration_info, $request_info, $requests. These match the arguments passed to the C version of the same API. Note that they are not entirely complete objects but are functional ``enough'' at this point in time.

$request_info object functions

     getMode ()
         Returns the mode of the request. See the MODES section for
         list of valid modes.
 
         $mode = $request->getMode();
 
     getRootOID ()
         Returns a NetSNMP::OID object that describes the registration
         point that the handler is getting called for (in case you
         register one handler function with multiple OIDs, which should
         be rare anyway)
 
         $root_oid = $request->getRootOID();
 
 

$request object functions

     next ()
         Returns the next request in the list or undef if there is no
         next request.
 
         $request = $request->next();
 
     getOID ()
         Returns the oid of the request (a NetSNMP::OID class).
 
         $oid = $request->getOID();
 
     setOID (new NetSNMP::OID("someoid"))
         Sets the OID of the request to a passed oid value.  This
         should generally only be done during handling of GETNEXT
         requests.
 
         $request->setOID(new NetSNMP::OID("someoid"));
 
     getValue ()
         Returns the value of the request. Used for example when
         setting values.
 
         $value = $request->getValue();
 
         FIXME: how to get the type of the value? Is it even available?
                [Wes: no, not yet.]
 
     setValue ( TYPE, DATA )
         Sets the data to be returned to the daemon.
 
         Returns 1 on success, 0 on error.
 
         TYPE - Type of the data. See NetSNMP::ASN for valid types.
         DATA - The data to return.
 
         $ret = $request->setValue(ASN_OCTET_STR, "test");
 
     setError ( REQUEST_INFO, ERROR_CODE )
         Sets the given error code for the request. See the ERROR CODES
         section for list of valid codes.
 
         $request->setError($request_info, SNMP_ERR_NOTWRITABLE);
 
     getProcessed ()
         The processed flag indicates that a request does not need to
         be dealt with because someone else (a higher handler) has
         dealt with it already.
 
         $processed = $request->getProcessed();
 
     setProcessed ( PROCESSED )
         Sets the processed flag flag in the request.  You generally
         should not have to set this yourself.
 
         PROCESSED - 0 = false, 1 = true
 
         $request->setProcessed(1);
 
     getDelegated ()
         If you can handle a request in the background or at a future
         time (EG, you're waiting on a file handle, or network traffic,
         or ...), the delegated flag can be set in the request.  When
         the request is processed in the future the flag should be set
         back to 0 so the agent will know that it can wrap up the
         original request and send it back to the manager.  This has
         not been tested within perl, but it hopefully should work.
 
         $delegated = $request->getDelegated();
 
     setDelegated ( DELEGATED )
         Sets the delegated flag.
 
         DELEGATED - 0 = false, 1 = true
 
         $request->setDelegated(1);
 
     getRepeat ()
         The repeat flag indicates that a getbulk operation is being
         handled and this indicates how many answers need to be
         returned.  Generally, if you didn't register to directly
         handle getbulk support yourself, you won't need to deal with
         this value.
 
         $repeat = $request->getRepeat();
 
     setRepeat ( REPEAT )
         Sets the repeat count (decrement after answering requests if
         you handle getbulk requests yourself)
 
         REPEAT -  repeat count FIXME
 
         $request->setRepeat(5);
 
     getSourceIp ()
 
         Gets the IPv4 address of the device making the request to the handler.
 
         use Socket;
         print "Source: ", inet_ntoa($request->getSourceIp()), "\n";
 
     getDestIp ()
 
         Gets the IPv4 address of the destination that the request was sent to.
 
         use Socket;
         print "Destination: ", inet_ntoa($request->getDestIp()), "\n";
 
 

MODES

         MODE_GET
         MODE_GETBULK
         MODE_GETNEXT
         MODE_SET_ACTION
         MODE_SET_BEGIN
         MODE_SET_COMMIT
         MODE_SET_FREE
         MODE_SET_RESERVE1
         MODE_SET_RESERVE2
         MODE_SET_UNDO
 
 

ERROR CODES

         SNMP_ERR_NOERROR
         SNMP_ERR_TOOBIG
         SNMP_ERR_NOSUCHNAME
         SNMP_ERR_BADVALUE
         SNMP_ERR_READONLY
         SNMP_ERR_GENERR
         SNMP_ERR_NOACCESS
         SNMP_ERR_WRONGTYPE
         SNMP_ERR_WRONGLENGTH
         SNMP_ERR_WRONGENCODING
         SNMP_ERR_WRONGVALUE
         SNMP_ERR_NOCREATION
         SNMP_ERR_INCONSISTENTVALUE
         SNMP_ERR_RESOURCEUNAVAILABLE
         SNMP_ERR_COMMITFAILED
         SNMP_ERR_UNDOFAILED
         SNMP_ERR_AUTHORIZATIONERROR
         SNMP_ERR_NOTWRITABLE
 
 

AUTHOR

Please mail the net-snmp-users@lists.sourceforge.net mailing list for help, questions or comments about this module.

Module written by:
   Wes Hardaker  <hardaker@users.sourceforge.net>

Documentation written by:
   Toni Willberg <toniw@iki.fi>
   Wes Hardaker  <hardaker@users.sourceforge.net>

SEE ALSO

NetSNMP::OID(3), NetSNMP::ASN(3), perl(1).