.\" /*********************************************************** .\" Copyright 1989 by Carnegie Mellon University .\" .\" All Rights Reserved .\" .\" Permission to use, copy, modify, and distribute this software and its .\" documentation for any purpose and without fee is hereby granted, .\" provided that the above copyright notice appear in all copies and that .\" both that copyright notice and this permission notice appear in .\" supporting documentation, and that the name of CMU not be .\" used in advertising or publicity pertaining to distribution of the .\" software without specific, written prior permission. .\" .\" CMU DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING .\" ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL .\" CMU BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR .\" ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, .\" WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, .\" ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS .\" SOFTWARE. .\" ******************************************************************/ .TH SNMP_SESS_API 3snmp "07 Mar 2002" V5.4.3.pre1 "Net-SNMP" .UC 5 .SH NAME snmp_sess_init, snmp_sess_open, snmp_sess_session, snmp_sess_send, snmp_sess_async_send, snmp_sess_select_info, snmp_sess_read, snmp_sess_timeout, snmp_sess_close, snmp_sess_error - session functions .SH SYNOPSIS .B #include .PP .BI "void snmp_sess_init(struct snmp_session *" session ");" .PP .BI "void *snmp_sess_open(struct snmp_session *" session ");" .PP .BI "struct snmp_session *snmp_sess_session(void *" handle ");" .PP .BI "int snmp_sess_send(void *" handle ", struct snmp_pdu *" pdu ");" .PP .BI "int snmp_sess_async_send(void *" handle "," .br .BI " struct snmp_pdu *" pdu ", " .br .BI " snmp_callback " callback ", " .br .BI " void *" callbackData ");" .PP .BI "int snmp_sess_select_info(void *" handle "," .br .BI " int *" numfds ", fd_set *" fdset ", " .br .BI " struct timeval *" timeout ", " .br .BI " int *" block ");" .PP .BI "int snmp_sess_read(void *" handle ", fd_set *" fdset ");" .PP .BI "void snmp_sess_timeout(void *" handle ");" .PP .BI "int snmp_sess_close(void *" handle ");" .PP .BI "void snmp_sess_error(void *" handle ", int *" pcliberr ", " .br .BI " int *" psnmperr ", char **" pperrstring ");" .SH DESCRIPTION These functions define a subset of the API that can be used to manage single SNMP sessions in a multi-threaded application. Except for .BR snmp_sess_session() , these functions are single session versions of the traditional SNMP library API. .PP Note that these functions use an opaque pointer .RI ( handle in the above prototypes) to identify a single session in lieu of a .I session pointer (as in the traditional API). .PP .B 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 .B snmp_sess_open() to create an SNMP session, the structure is no longer used. Instead the opaque pointer returned by .B snmp_sess_open() is used to refer to that session henceforth. .PP SNMP sessions that are created with .B snmp_sess_open() are not affected by, and SHOULD NOT BE USED WITH, .BR snmp_select_info() ", " snmp_read() ", " snmp_timeout() " nor" .BR snmp_close() . Rather the equivalent single session functions described here should be used. .PP .B snmp_sess_init() and .B snmp_sess_open() each take as input a pointer to a struct snmp_session object. This structure contains information for a set of transactions that will share similar transport characteristics. .B snmp_sess_session() takes the opaque session handle and returns a pointer to its associated struct snmp_session. .PP .B snmp_sess_send() and .B snmp_sess_async_send() each take a .I pdu parameter, which points to a struct snmp_pdu object containing information that describes a transaction that will be performed over an open session. .PP Consult snmp_api.h for the definitions of these structures. .PP .BR snmp_sess_select_info() ", " snmp_sess_read() " and " snmp_sess_timeout() provide an interface for the use of the .BR select (2) system call so that SNMP transactions for a single session can occur asynchronously. .PP .B snmp_sess_select_info() is passed the information that would have been passed to .BR select (2) in the absence of SNMP. For example, this might include file descriptors associated with the main loop of a graphical application. This information is modified so that SNMP will get the service it requires from the call to .BR select (2). In this case, .IR numfds ", " fdset " and " timeout correspond to the .IR nfds ", " readfds " and " timeout arguments to .BR select (2) respectively. The only exception is that timeout must ALWAYS point to an allocated (but perhaps uninitialized) .I struct timeval (it cannot be NULL as for .BR select (2)). If .I timeout would have been passed as NULL, .I block is instead set to true, and .I timeout is treated as undefined. This same rule applies upon return from .BR snmp_select_info() . .PP After calling .B snmp_sess_select_info() , .BR select (2) should be called with the returned data. When it returns, .B snmp_sess_read() should then be called with the .I fd_set returned from .BR select (2). This will read any input from this session's SNMP socket. If .BR select (2) times out (that is, it returns zero), .B snmp_sess_timeout() should be called to see if a timeout has occurred on the SNMP session. .SH DIAGNOSTICS .PP Error return status from .B snmp_sess_open() is indicated by return of a NULL pointer. Error return status from .B snmp_sess_close() and .B snmp_sess_send() is indicated by a return value of 0. A successful status will return 1. .PP Further information can be obtained by using .B snmp_sess_error() to see what type of error has occurred. This function returns the SNMP .I snmp_errno variable, the value of the system .I errno variable, and a string interpretation of both variables. The string must be freed after use by the caller. .PP For errors returned by .BR snmp_sess_open() , use the corresponding function .B snmp_error() instead of .BR snmp_sess_error() . .PP Consult snmp_api.h for the complete set of SNMP library error values. The SNMP library error value .IR snmperr can be one of the following values: .RS 2n .IP SNMPERR_GENERR \w'SNMPERR_BAD_REPETITIONS'u+2n A generic error occurred. .IP SNMPERR_BAD_LOCPORT \w'SNMPERR_BAD_REPETITIONS'u+2n The local port was bad because it had already been allocated or permission was denied. .IP SNMPERR_BAD_ADDRESS \w'SNMPERR_BAD_REPETITIONS'u+2n The host name or address given was not useable. .IP SNMPERR_BAD_SESSION \w'SNMPERR_BAD_REPETITIONS'u+2n The specified session was not open. .IP SNMPERR_TOO_LONG \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_NO_SOCKET \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_V2_IN_V1 \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_V1_IN_V2 \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_REPEATERS \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_REPETITIONS \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_ASN1_BUILD \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_SENDTO \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_RCVFROM \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_PARSE \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_VERSION \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_BAD_COMMUNITY \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_NOAUTH_DESPRIV \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_ABORT \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_UNKNOWN_PDU \w'SNMPERR_BAD_REPETITIONS'u+2n .IP SNMPERR_TIMEOUT \w'SNMPERR_BAD_REPETITIONS'u+2n .RE .PP .SH "SEE ALSO" .BR select "(2), " snmp_api "(3), " snmp_api.h