snmp_error, snmp_api_errstring - send and receive SNMP messages

SYNOPSIS

       #include <net-snmp/session_api.h>

       void snmp_sess_init ( struct snmp_session * );

       struct snmp_session * snmp_open ( struct snmp_session *);
              /* Input parameter not used in active sessions */

       int snmp_send ( struct snmp_session *session,
              struct snmp_pdu *pdu );

       int snmp_select_info ( int *numfds, fd_set *fdset,
              struct timeval *timeout, int *block );

       void snmp_read ( fd_set *fdset );

       void snmp_timeout ( void );

       int snmp_close ( struct snmp_session *session );

       void snmp_free_pdu ( struct snmp_pdu *pdu );

       void snmp_error ( struct snmp_session *session,
              int *pcliberr, int *psnmperr, char **pperrstring );

       char *snmp_api_errstring ( int snmperr );

       void snmp_perror ( char * msg );
              /* for parsing errors only */

       void snmp_sess_perror (char * msg, struct snmp_session *);
              /* all other SNMP library errors */

DESCRIPTION

       Snmp_sess_init  prepares  a  struct snmp_session that sources transport
       characteristics and common information that will be used for a  set  of
       SNMP transactions.  After this structure is passed to snmp_open to cre-
       ate an SNMP session, the structure is not used.

       Snmp_open returns a  pointer  to  a  newly-formed  struct  snmp_session
       object,  which  the  application  must use to reference the active SNMP
       session.

       Snmp_send and snmp_free_pdu each take as input a pointer  to  a  struct
       snmp_pdu  object.  This structure contains information that describes a
       transaction that will be performed over an open session.

       Consult snmp_api.h for the definitions of these structures.


       After  calling  snmp_select_info,  select  is  called with the returned
       data.  When select returns, snmp_read should be called with the  fd_set
       returned  from  select  to  read  each  SNMP socket that has input.  If
       select times out, snmp_timeout should be called to see if  the  timeout
       was intended for SNMP.

DIAGNOSTICS

       Previous versions of the library used snmp_get_errno to read the global
       variable snmp_errno which may have held the  error  status  within  the
       SNMP  library.   The  existing method snmp_perror should be used to log
       ASN.1 coding errors only.

       The new method snmp_sess_perror is  provided  to  capture  errors  that
       occur   during   the   processing   of   a   particular  SNMP  session.
       Snmp_sess_perror calls snmp_error function to obtain  the  "C"  library
       error  errno  ,  the  SNMP library error snmperr , and the SNMP library
       detailed error message that is associated with an error  that  occurred
       during a given session.

       Note  that  in  all cases except one, snmp_sess_perror should be handed
       the  struct  snmp_session  *  pointer  returned  from  snmp_open.    If
       snmp_open  returns a null pointer, pass the INPUT struct snmp_session *
       pointer used to call snmp_open.

       Error return status from  snmp_close  and  snmp_send  is  indicated  by
       return  of  0.   A successful status will return a 1 for snmp_close and
       the request id of the packet for  snmp_send.   Upon  successful  return
       from snmp_send the pdu will be freed by the library.

       Consult  snmp_api.h  for the complete set of SNMP library error values.
       The SNMP library error value snmperr can be one of the  following  val-
       ues:

         SNMPERR_GENERR           A generic error occurred.

         SNMPERR_BAD_LOCPORT      The  local  port  was  bad  because  it  had
                                  already been  allocated  or  permission  was
                                  denied.

         SNMPERR_BAD_ADDRESS      The  host name or address given was not use-
                                  able.

         SNMPERR_BAD_SESSION      The specified session was not open.

         SNMPERR_TOO_LONG

         SNMPERR_NO_SOCKET

         SNMPERR_V2_IN_V1

         SNMPERR_V1_IN_V2

         SNMPERR_ABORT

         SNMPERR_UNKNOWN_PDU

         SNMPERR_TIMEOUT

       A string  representation  of  the  error  code  can  be  obtained  with
       snmp_api_errstring,  and  a standard error message may be printed using
       snmp_perror that functions like the perror standard routine.

SEE ALSO

       select(2), snmp_api.h



4.2 Berkeley Distribution         21 Oct 1999                      SNMP_API(3)