Re: A simple C program which sends v2c informs do not make retries in case of unavailable destination

Hi,
  Maybe have a look at the source to snmptrap to see how its done there?

snmp_send seems to be a fire and forget.

You probably want snmp_synch_response or to look how it does the select,
read and timeout functions and copy that.

 - Craig


On Thu, 28 Jan 2021 at 01:35, <[email protected]> wrote:

> Hello!
>
> Did anyone face the same behaviour?
> Why the retries are not accepted?
>
> What is necessary to do in order to resolve this situation?
>
> Best regards,
> Andrei Yahorau
>
>
>
> From:        Andrei Yahorau/IBA
> To:        [email protected]
> Date:        08.05.2020 10:37
> Subject:        A simple C program which sends v2c informs do not make
> retries in case of unavailable destination
> ------------------------------
>
>
> Hello Everyone!
>
> I have a question. I want to send SNMP v2c informs using C and net-snmp
> module in linux SLES 12.
> To do this I created the following simple program where everything comes
> to send_trap_to_sess() function :
>
> #include <net-snmp/net-snmp-config.h>
> #include <net-snmp/net-snmp-includes.h>
> oid             objid_sysuptime[] = { 1, 3, 6, 1, 2, 1, 1, 3, 0 };
> oid             objid_id[] = { 1,3,6,1,4,1,78945,1,1,2,4,0};
> oid             objid_name[] = { 1,3,6,1,4,1,78945,1,1,2,1,0};
> oid              trap_oid[] = {1,3,6,1,4,1,78945,1,1,1,1,1};
> int main()
> {
>    netsnmp_session session, *ss;
>    netsnmp_pdu    *pdu, *response;
>    char *trap = NULL;
>
>    char comm[] = "public";
>    snmp_sess_init( &session );
>    session.version = SNMP_VERSION_2c;
>    session.community = comm;
>    session.community_len = strlen(session.community);
>    session.peername = "192.168.4.10:1234";
>     session.retries = 3;
>     session.timeout = 1000;
>    ss = snmp_open(&session);
>    if (!ss) {
>      snmp_sess_perror("ack", &session);
>      exit(1);
>    }
>    pdu = snmp_pdu_create(SNMP_MSG_INFORM);
>    pdu->community = comm;
>    pdu->community_len = strlen(comm);
>    pdu->trap_type = SNMP_TRAP_ENTERPRISESPECIFIC;
>    long sysuptime;
>    char csysuptime [20];
>    sysuptime = get_uptime ();
>    sprintf (csysuptime, "%ld", sysuptime);
>    trap = csysuptime;
>    snmp_add_var (pdu, objid_sysuptime, sizeof (objid_sysuptime)/sizeof
> (oid),'t', trap);
>    snmp_add_var(pdu, trap_oid, OID_LENGTH(trap_oid), 'o',
> "1.3.6.1.4.1.78945.1.1.1.1.1");
>    snmp_add_var(pdu, objid_name, OID_LENGTH(objid_name), 's', "Test Name"
> );
>    snmp_add_var(pdu, objid_id, OID_LENGTH(objid_id) , 'i', "5468");
>    send_trap_to_sess (ss, pdu);
>    snmp_close(ss);
>    return (0);
> }
>
>
> Frankly speaking this is modified part of code taken from
> *https://stackoverflow.com/questions/30050542/how-to-send-v2-traps-in-net-snmp-using-c*
> <https://stackoverflow.com/questions/30050542/how-to-send-v2-traps-in-net-snmp-using-c>  where
> a user asked how to send snmp v2c trap using C.
> Here I modified creation of pdu:
> pdu = snmp_pdu_create(SNMP_MSG_INFORM);
> and added assignments of retries and timeout values for informs
> session.retries = 3;
> session.timeout = 1000;
>
> This example works quite well. I see that it sends inform request in
> wireshark output. But there is one problem: If the destination is not
> available it will not do any retries despite that this is an inform.
>
> Could you please give me a suggestion what I do wrong here?
> Thank you in advance.
>
> Best regards,
> Andrei Yahorau
> _______________________________________________
> Net-snmp-coders mailing list
> [email protected]
> https://lists.sourceforge.net/lists/listinfo/net-snmp-coders
>

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