Hello Graeme,
thanks for your prompt reply.
netsnmp_register_handler( reg ) is "hidden" in
printf("returned=%d\n", netsnmp_register_handler(reg));
I tried it before without printf and it was doing the same thing.
I have no other handlers and no other agents started.
I considered switching snmp logging with LOG_DEBUG level/priority but I
did not find any function how to set the level.
Is there anything else I could try?
Thanks.
Milan
On Thu, August 9, 2007 4:53 pm, Graeme Wilson wrote:
> Hi Milan,
>
>
> From a quick look at your code it looks like you've missed a crucial
> line to register the handler:
>
> netsnmp_register_handler( reg );
>
> Which you need to do after your line:
> reg = netsnmp_handler_registration_create(...)
>
> Also, one important point (I forgot to mention previously), if there are
> any other handlers which register for specific OIDs (e.g.
> .1.3.6.1.2.1.1.4.0) - these will be called instead of your generic
> handler.
>
> Hope that helps.
> Graeme
>
>
>
>
>
>
>> -----Original Message-----
>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>> Sent: 09 August 2007 15:43
>> To: Graeme Wilson
>> Cc: net-snmp-users@lists.sourceforge.net
>> Subject: RE: Newbie question: writing a simple agent
>>
>>
>> Hello Graeme,
>>
>>
>> sorry for bothering you again.
>>
>> I have tried to merge your code with MFD code. I am obviously
>> doing something wrong. When I run snmpwalk on the agent I can see that
>> agent_check_and_process(1) in the main loop finishes but the handler
>> does not get called.
>>
>> I get error message from the agent:
>>
>>
>> Connection from UDP: [127.0.0.1]:-32767
>>
>>
>> I assume this means this request was not handled by the agent.
>>
>>
>> I do not know if netsnmp_register_handler(reg) is successful,
>> it returns 0. I was googling but I did not find meaning of this value.
>>
>> Did I miss something in my main()? I am attaching short code.
>>
>>
>> Thank you and please do net get angry with me for so many mails.
>>
>>
>> Milan
>>
>>
>> ----
>>
>>
>>
>> #include "agent.h"
>> #include "agent_error.h"
>>
>>
>> static int keep_running;
>>
>> void stop_server(UNUSED int a) { keep_running = 0; }
>>
>>
>> /* Ippc function which will be called for all OIDs below the
>> root one registered above */ int IppcOidHandler(UNUSED
>> netsnmp_mib_handler *handler, UNUSED netsnmp_handler_registration
>> *reginfo,
>> UNUSED netsnmp_agent_request_info *reqinfo,
>> netsnmp_request_info *requests) { int ret = SNMP_ERR_NOERROR;
>>
>> printf("Received SNMP request"); for (unsigned i = 0; i <
>> requests->range_end_len; i++) { printf("%d.",
>> (int)requests->range_end[i]);
>> }
>> printf("\n");
>>
>> switch(reqinfo->mode) {
>> case MODE_GET: /* Call some other code to process the 'requests' argument
>> */
>> //ret = myData->getData( requests );
>> break; case MODE_GETNEXT: /* Call some other code to process the
>> 'requests' argument */
>> //ret = myData->getNextData( requests );
>> break; default:
>> /* we should never get here in my code */
>> //iRet = SNMP_ERR_GENERR;
>> break; }
>> return 1; //ret; }
>>
>>
>> int main (UNUSED int argc, UNUSED char **argv) { netsnmp_mib_handler
>> *handler;
>> netsnmp_handler_registration *reg;
>>
>> static oid root_oid[] = { 1, 3, 6 };
>>
>> snmp_enable_stderrlog();
>>
>> SOCK_STARTUP;
>>
>>
>> init_agent("ippc agent");
>>
>> init_snmp("ippc agent");
>>
>> init_master_agent(); /* open the port to listen on (defaults to
>> udp:161) */
>>
>>
>> keep_running = 1; signal(SIGTERM, stop_server); signal(SIGINT,
>> stop_server);
>>
>> handler = netsnmp_create_handler("IppcOIDHandler", &IppcOidHandler );
>>
>>
>> if (handler) { reg = netsnmp_handler_registration_create( "IppcHandler",
>> handler, root_oid, OID_LENGTH(root_oid),
>> 0);
>>
>>
>> printf("returned=%d\n", netsnmp_register_handler(reg)); }
>> else { exit(1); }
>>
>>
>>
>> while(keep_running) { agent_check_and_process(1); /* 0 == don't block */
>> printf("mainloop\n"); }
>>
>>
>> /* at shutdown time */
>> netsnmp_unregister_handler(reg); snmp_shutdown("ippc agent");
>> SOCK_CLEANUP;
>>
>>
>> return 0; }
>>
>>
>>
>>
>>
>> ----
>>
>>
>>
>> On Wed, August 8, 2007 4:10 pm, Graeme Wilson wrote:
>>
>>> Hi Milan,
>>>
>>>
>>>
>>> No worries about the questions.
>>>
>>>
>>>
>>> For my subagent (binary/executable) I doctored an existing
>>>
>> 'main' that
>>
>>> I had from when I'd created a subagent with mib2c - its
>>>
>> just like your
>>> example below: - init_agent - etc etc
>>> - register your handler here
>>> - loop (agent_check_and_process)
>>> - etc etc
>>>
>>>
>>>
>>> Cheers
>>> Graeme
>>>
>>>
>>>
>>>
>>>> -----Original Message-----
>>>> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
>>>> Sent: 08 August 2007 14:47
>>>> To: Graeme Wilson
>>>> Cc: net-snmp-users@lists.sourceforge.net
>>>> Subject: RE: Newbie question: writing a simple agent
>>>>
>>>>
>>>>
>>>> Hello Graeme,
>>>>
>>>>
>>>>
>>>> I went through your code and it seems it is exactly what I need.
>>>>
>>>>
>>>>
>>>> I am just confused about one thing: how does it plug into snmpd?
>>>>
>>>>
>>>>
>>>> I understand that I need to do in agent main() registration (and
>>>> un-registration at agent finish) but what do I actually generate?
>>>>
>>>> Should I create a binary like in MFD example and loop using
>>>> agent_check_and_process() or snmp_select_info() or should I create
>>>> some kind of .so that does mere regsitration and finishes?
>>>>
>>>> In the former case the scenario is
>>>> - init_agent
>>>> - init_snmp
>>>> - init_master_agent();
>>>> - register handler
>>>> - loop
>>>> - un-register handler
>>>> - snmp_shutdown
>>>>
>>>>
>>>>
>>>> or am I missing something?
>>>>
>>>> Sorry for asking you newbie trivial questions :-)
>>>>
>>>>
>>>>
>>>> Thanks.
>>>>
>>>>
>>>>
>>>> Milan
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> On Wed, August 8, 2007 11:11 am, Graeme Wilson wrote:
>>>>
>>>>
>>>>>
>>>>
>>>>> Hi,
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> I have done something similar recently (I provide some
>>>>>
>> sample code
>>>>> below - but note that ultimately everything is still done within
>>>>>
>>>> the agent).
>>>>> My Agent simply registers the root OID of the MIB it will
>>>>>
>>>>>
>>>> handle and
>>>>> some other function knows all about the data and the
>> specific OIDs
>>>>> that the Agent handles. I just registered a generic
>> handler for the
>>>>> root oid and
>>>> then when it
>>>>> is called, the handler make appropriate calls to handle the
>>>> request.
>>>>> I guess in your case you could then request the data (if
>>>>>
>>>>>
>>>> any) from the
>>>>> process/thread that holds the Data and OIDS.
>>>>>
>>>>> Hope that helps.
>>>>> Graeme
>>>>> -------------
>>>>> /* In your main/initialise function */
>>>>> netsnmp_mib_handler* handler = netsnmp_create_handler(
>>>>> "GenericOIDHandler", &genericOidHandler );
>>>>>
>>>>>
>>>>>
>>>>>
>>>>> netsnmp_handler_registration* reg =
>>>>> netsnmp_handler_registration_create( "GenericHandler", handler,
>>>>> root_oid, OID_LENGTH(root_oid), 0 );
>>>>>
>>>>> netsnmp_register_handler( reg );
>>>>>
>>>>>
>>>>>
>>>>> /* Generic function which will be called for all OIDs below
>>>>>
>>>>>
>>>> the root
>>>>> one registered above */ int genericOidHandler(
>> netsnmp_mib_handler
>>>>> *handler, netsnmp_handler_registration *reginfo,
>>>>> netsnmp_agent_request_info *reqinfo, netsnmp_request_info
>>>> *requests )
>>>>
>>>>
>>>>> { int ret = SNMP_ERR_NOERROR;
>>>>>
>>>>>
>>>>>
>>>>> switch(reqinfo->mode) { case MODE_GET: /* Call some other code to
>>>>> process the 'requests' argument */ ret = myData->getData(
>> requests
>>>>> ); break; case MODE_GETNEXT: /* Call some other code to
>>>>>
>> process the
>>>>> 'requests'
>>>>> argument */ ret = myData->getNextData( requests ); break;
>> default:
>>
>>>>> /* we should never get here in my code */ iRet = SNMP_ERR_GENERR;
>>>>> break; } return ret; }
>>>>>
>>>>>
>>>>>
>>>>>
>>>>>> -----Original Message-----
>>>>>> From: [EMAIL PROTECTED]
>>>>>> [mailto:[EMAIL PROTECTED] On
>>>>>>
>> Behalf Of
>>
>>>>>> [EMAIL PROTECTED]
>>>>>> Sent: 08 August 2007 06:51
>>>>>> To: Mike Ayers
>>>>>> Cc: net-snmp-users@lists.sourceforge.net
>>>>>> Subject: RE: Newbie question: writing a simple agent
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Hello Mike,
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> thanks for replying to my question.
>>>>>>
>>>>>> I understand that a standard approach is to register the
>>>>>>
>>>>>>
>>>> agent for a
>>>>>> range of OISs and to let the agent to be OID aware while
>> the other
>>>>>> process should take care of the underlaying data.
>>>>>>
>>>>>> However, I was asked to write an agent that would NOT be
>>>>>>
>>>>>>
>>>> OID-aware.
>>>>
>>>>
>>>>>> All it would know it is responsible for a range of OIDs without
>>>>>> knowing any details. It would forward complete OIDs to the
>>>>>> other process that would take care about OID
>>>> disassembly/translation, data
>>>>>> manipulation etc.
>>>>>>
>>>>>> I am wondering if this is possible within the Net SNMP
>>>>>>
>> API, at all.
>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> If so, where should I start?
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Thanks.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Milan
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Tue, August 7, 2007 11:44 pm, Mike Ayers wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>>>
>>>>>>
>>>>>>>> From: [EMAIL PROTECTED]
>>>>>>>> [mailto:[EMAIL PROTECTED] On
>>>>>>>>
>>>>>>>>
>>>> Behalf Of
>>>>
>>>>
>>>>>>>> [EMAIL PROTECTED]
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>> The agent itself will not be aware of individual OIDs
>>>>>>>>
>> and their
>>>>>>>> meaning. This will be done by the other process that also
>>>>>> holds the
>>>>>>>> actual data.
>>>>>>>
>>>>>>> This is a bit of a design problem as stated. The (sub)agent
>>>>>>> is responsible for managing its OID range, and therefore it is
>>>>>>> not possible to have a subagent completely unaware of the
>>>>>>> OIDs.
>>>>>>>
>>>>>> This does
>>>>>>
>>>>>>
>>>>>>
>>>>>>> not, however, mean that the subagent needs to be aware of
>>>> the data
>>>>>>> underlying the MIB.
>>>>>>>
>>>>>>> A common paradigm is to have the subagent register for
>>>>>>>
>>>>>>>
>>>> the range of
>>>>>>> values (table, MIB, whatever) that it will manage, and
>>>> have the OP
>>>>>>> (other
>>>>>>> process) manage the data within the range. The agent does OID
>>>>>>> assembly/disassembly (i.e. breaking OIDs into range part
>>>>>> and specific
>>>>>>> part), possibly reformat the specific part to make it more
>>>>>>> understandable to the OP (thus only the subagent need be
>>>>>> MIB aware).
>>>>>>
>>>>>>
>>>>>>
>>>>>>> The OP returns the values for the requested data, then
>>>>>>>
>>>>>>>
>>>> the subagent
>>>>>>> formats and assembles the response.
>>>>>>>
>>>>>>>
>>>>>>> HTH,
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>> Mike
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>>
>>>>>>
>>>>
>> ---------------------------------------------------------------------
>>
>>>>
>>>>>> -
>>>>>>
>>>>>>
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>>>>>>>
>>>>>>>
>>>>>>
>>>>>>
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>>>>>>
>>>>>
>>>>>
>>>>>
>>>>
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>>
>
>
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