mtetrigger.c

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                    return;
                }
                vtmp->type = ASN_NULL;
                snmp_set_var_objid( vtmp, vp1->name, vp1->name_length );
                vtmp->next_variable = vp2;
                if (vp2_prev) {
                    vp2_prev->next_variable = vtmp;
                } else {
                    entry->old_results      = vtmp;
                }
                vp2_prev   = vtmp;
                vp1->index = MTE_ARMED_ALL;	/* XXX - plus a new flag */
                vp1_prev   = vp1;
                vp1        = vp1->next_variable;
            }
            else if ( cmp == 0 ) {
                /*
                 * If it's a continuing entry, just copy across the armed flags
                 */
                vp1->index = vp2->index;
                vp1_prev   = vp1;
                vp1        = vp1->next_variable;
                vp2_prev   = vp2;
                vp2        = vp2->next_variable;
            } else {
                /*
                 * If a value has just disappeared, insert a
                 * matching dummy entry into the current result list.
                 *
                 * XXX - check how this is best done.
                 *
                 */
                if ( vp2->type != ASN_NULL ) {
                    vtmp = SNMP_MALLOC_TYPEDEF( netsnmp_variable_list );
                    if (!vtmp) {
                        _mteTrigger_failure(
                                 "failed to create mteTrigger temp varbind");
                        return;
                    }
                    vtmp->type = ASN_NULL;
                    snmp_set_var_objid( vtmp, vp2->name, vp2->name_length );
                    vtmp->next_variable = vp1;
                    if (vp1_prev) {
                        vp1_prev->next_variable = vtmp;
                    } else {
                        entry->old_results      = vtmp;
                    }
                    vp1_prev = vtmp;
                    vp2_prev = vp2;
                    vp2      = vp2->next_variable;
                } else {
                    /*
                     * But only if this entry has *just* disappeared.  If the
                     * entry from the last run was a dummy too, then remove it.
                     *   (leaving vp2_prev unchanged)
                     */
                    vtmp = vp2;
                    if (vp2_prev) {
                        vp2_prev->next_variable = vp2->next_variable;
                    } else {
                        entry->old_results      = vp2->next_variable;
                    }
                    vp2  = vp2->next_variable;
                    vtmp->next_variable = NULL;
                    snmp_free_varbind( vtmp );
                }
            }
        } else {
            /*
             * No more old results to compare.
             * Either all remaining values have only just been created ...
             *   (and we need to create dummy 'old' entries for them)
             */
            if ( vp2_prev ) {
                vtmp = SNMP_MALLOC_TYPEDEF( netsnmp_variable_list );
                if (!vtmp) {
                    _mteTrigger_failure(
                             "failed to create mteTrigger temp varbind");
                    return;
                }
                vtmp->type = ASN_NULL;
                snmp_set_var_objid( vtmp, vp1->name, vp1->name_length );
                vtmp->next_variable     = vp2_prev->next_variable;
                vp2_prev->next_variable = vtmp;
                vp2_prev                = vtmp;
            }
            /*
             * ... or this is the first run through
             *   (and there were no old results at all)
             *
             * In either case, mark the current entry as armed and new.
             * Note that we no longer need to maintain 'vp1_prev'
             */
            vp1->index = MTE_ARMED_ALL;	/* XXX - plus a new flag */
            vp1        = vp1->next_variable;
        }
    }

    /*
     * ... and then work through these result(s), deciding
     *     whether or not to trigger the corresponding event.
     *
     *  Note that there's no point in evaluating Existence or
     *    Boolean tests if there's no corresponding event.
     *   (Even if the trigger matched, nothing would be done anyway).
     */
    if ((entry->mteTriggerTest & MTE_TRIGGER_EXISTENCE) &&
        (entry->mteTExEvent[0] != '\0' )) {
        /*
         * If we don't have a record of previous results,
         * this must be the first time through, so consider
         * the mteTriggerExistenceStartup tests.
         */
        if ( !entry->old_results ) {
            /*
             * With the 'present(0)' test, the trigger should fire
             *   for each value in the varbind list returned
             *   (whether the monitored value is wildcarded or not).
             */
            if (entry->mteTExTest & entry->mteTExStartup & MTE_EXIST_PRESENT) {
                for (vp1 = var; vp1; vp1=vp1->next_variable) {
                    DEBUGMSGTL(( "disman:event:trigger:fire",
                                 "Firing initial existence test: "));
                    DEBUGMSGOID(("disman:event:trigger:fire",
                                 vp1->name, vp1->name_length));
                    DEBUGMSG((   "disman:event:trigger:fire",
                                 " (present)\n"));;
                    entry->mteTriggerXOwner   = entry->mteTExObjOwner;
                    entry->mteTriggerXObjects = entry->mteTExObjects;
                    entry->mteTriggerFired    = vp1;
                    n = entry->mteTriggerValueID_len;
                    mteEvent_fire(entry->mteTExEvOwner, entry->mteTExEvent, 
                                  entry, vp1->name+n, vp1->name_length-n);
                }
            }
            /*
             * An initial 'absent(1)' test only makes sense when
             *   monitoring a non-wildcarded OID (how would we know
             *   which rows of the table "ought" to exist, but don't?)
             */
            if (entry->mteTExTest & entry->mteTExStartup & MTE_EXIST_ABSENT) {
                if (!(entry->flags & MTE_TRIGGER_FLAG_VWILD) &&
                    vp1->type == ASN_NULL ) {
                    DEBUGMSGTL(( "disman:event:trigger:fire",
                                 "Firing initial existence test: "));
                    DEBUGMSGOID(("disman:event:trigger:fire",
                                 var->name, var->name_length));
                    DEBUGMSG((   "disman:event:trigger:fire",
                                 " (absent)\n"));;
                    entry->mteTriggerXOwner   = entry->mteTExObjOwner;
                    entry->mteTriggerXObjects = entry->mteTExObjects;
                    /*
                     * It's unclear what value the 'mteHotValue' payload
                     *  should take when a monitored instance does not
                     *  exist on startup. The only sensible option is
                     *  to report a NULL value, but this clashes with
                     * the syntax of the mteHotValue MIB object.
                     */
                    entry->mteTriggerFired    = vp1;
                    n = entry->mteTriggerValueID_len;
                    mteEvent_fire(entry->mteTExEvOwner, entry->mteTExEvent, 
                                  entry, vp1->name+n, vp1->name_length-n);
                }
            }
        } /* !old_results */
            /*
             * Otherwise, compare the current set of results with
             * the previous ones, looking for changes.  We can
             * assume that the two lists match (see above).
             */
        else {
            for (vp1 = var, vp2 = entry->old_results;
                 vp1;
                 vp1=vp1->next_variable, vp2=vp2->next_variable) {

                /* Use this field to indicate that the trigger should fire */
                entry->mteTriggerFired = NULL;
                reason                 = NULL;

                if ((entry->mteTExTest & MTE_EXIST_PRESENT) &&
                    (vp1->type != ASN_NULL) &&
                    (vp2->type == ASN_NULL)) {
                    /* A new instance has appeared */
                    entry->mteTriggerFired = vp1;
                    reason = "(present)";

                } else if ((entry->mteTExTest & MTE_EXIST_ABSENT) &&
                    (vp1->type == ASN_NULL) &&
                    (vp2->type != ASN_NULL)) {

                    /*
                     * A previous instance has disappeared.
                     *
                     * It's unclear what value the 'mteHotValue' payload
                     *  should take when this happens - the previous
                     *  value (vp2), or a NULL value (vp1) ?
                     * NULL makes more sense logically, but clashes
                     *  with the syntax of the mteHotValue MIB object.
                     */
                    entry->mteTriggerFired = vp2;
                    reason = "(absent)";

                } else if ((entry->mteTExTest & MTE_EXIST_CHANGED) &&
                    ((vp1->val_len != vp2->val_len) || 
                     (memcmp( vp1->val.string, vp2->val.string,
                              vp1->val_len) != 0 ))) {
                    /*
                     * This comparison detects changes in *any* type
                     *  of value, numeric or string (or even OID).
                     *
                     * Unfortunately, the default 'mteTriggerFired'
                     *  notification payload can't report non-numeric
                     *  changes properly (see syntax of 'mteHotValue')
                     */
                    entry->mteTriggerFired = vp1;
                    reason = "(changed)";
                }
                if ( entry->mteTriggerFired ) {
                    /*
                     * One of the above tests has matched,
                     *   so fire the trigger.
                     */
                    DEBUGMSGTL(( "disman:event:trigger:fire",
                                 "Firing existence test: "));
                    DEBUGMSGOID(("disman:event:trigger:fire",
                                 vp1->name, vp1->name_length));
                    DEBUGMSG((   "disman:event:trigger:fire",
                                 " %s\n", reason));;
                    entry->mteTriggerXOwner   = entry->mteTExObjOwner;
                    entry->mteTriggerXObjects = entry->mteTExObjects;
                    n = entry->mteTriggerValueID_len;
                    mteEvent_fire(entry->mteTExEvOwner, entry->mteTExEvent, 
                                  entry, vp1->name+n, vp1->name_length-n);
                }
            }
        } /* !old_results - end of else block */
    } /* MTE_TRIGGER_EXISTENCE */


    if (( entry->mteTriggerTest & MTE_TRIGGER_BOOLEAN   ) ||
        ( entry->mteTriggerTest & MTE_TRIGGER_THRESHOLD )) {
        /*
         * Although Existence tests can work with any syntax values,
         * Boolean and Threshold tests are integer-only.  Ensure that
         * the returned value(s) are appropriate.
         *
         * Note that we only need to check the first value, since all
         *  instances of a given object should have the same syntax.
         */
        switch (var->type) {
        case ASN_INTEGER:
        case ASN_COUNTER:
        case ASN_GAUGE:
        case ASN_TIMETICKS:
        case ASN_UINTEGER:
        case ASN_COUNTER64:
#ifdef NETSNMP_WITH_OPAQUE_SPECIAL_TYPES
        case ASN_OPAQUE_COUNTER64:
        case ASN_OPAQUE_U64:
        case ASN_OPAQUE_I64:
#endif
            /* OK */
            break;
        default:
            /*
             * Other syntax values can't be used for Boolean/Theshold
             * tests. Report this as an error, and then rotate the
             * results ready for the next run, (which will presumably
             * also detect this as an error once again!)
             */
            DEBUGMSGTL(( "disman:event:trigger:fire",
                         "Returned non-integer result(s): "));
            DEBUGMSGOID(("disman:event:trigger:fire",
                         var->name, var->name_length));
            DEBUGMSG((   "disman:event:trigger:fire",
                         " (boolean/threshold) %d\n", var->type));;
            snmp_free_varbind( entry->old_results );
            entry->old_results = var;
            return;
        }


        /*
         * Retrieve the discontinuity markers for delta-valued samples.
         * (including sysUpTime.0 if not specified explicitly).
         */
        if ( entry->flags & MTE_TRIGGER_FLAG_DELTA ) {
            /*
             * We'll need sysUpTime.0 regardless...
             */
            DEBUGMSGTL(("disman:event:delta", "retrieve sysUpTime.0\n"));
            memset( &sysUT_var, 0, sizeof( netsnmp_variable_list ));
            snmp_set_var_objid( &sysUT_var, _sysUpTime_instance,