Java example source code file (SnmpMibGroup.java)

This example Java source code file (SnmpMibGroup.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

acmchecker, hashtable, illegalaccessexception, jmx, long, object, override, serializable, snmp, snmpmibgroup, snmpmibnode, snmpmiboid, snmpmibtable, snmprequesttree, snmpstatusexception, util

The SnmpMibGroup.java Java example source code

/*
 * Copyright (c) 1999, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

package com.sun.jmx.snmp.agent;

// java imports
//
import java.io.Serializable;
import java.util.Hashtable;
import java.util.Vector;

// jmx imports
//
import com.sun.jmx.snmp.SnmpVarBind;
import com.sun.jmx.snmp.SnmpStatusException;


/**
 * Represents a node in an SNMP MIB which corresponds to a group.
 * This class allows subnodes to be registered below a group, providing
 * support for nested groups. The subnodes are registered at run time
 * when registering the nested groups in the global MIB OID tree.
 * <P>
 * This class is used by the class generated by <CODE>mibgen.
 * You should not need to use this class directly.
 *
 * <p>This API is a Sun Microsystems internal API  and is subject
 * to change without notice.</b>

 */

public abstract class SnmpMibGroup extends SnmpMibOid
    implements Serializable {

    // We will register the OID arcs leading to subgroups in this hashtable.
    // So for each arc in varList, if the arc is also in subgroups, it leads
    // to a subgroup, if it is not in subgroup, it leads either to a table
    // or to a variable.
    protected Hashtable<Long, Long> subgroups = null;

    /**
     * Tells whether the given arc identifies a table in this group.
     *
     * @param arc An OID arc.
     *
     * @return <CODE>true if `arc' leads to a table.
     */
    public abstract boolean      isTable(long arc);

    /**
     * Tells whether the given arc identifies a variable (scalar object) in
     * this group.
     *
     * @param arc An OID arc.
     *
     * @return <CODE>true if `arc' leads to a variable.
     */
    public abstract boolean      isVariable(long arc);

    /**
     * Tells whether the given arc identifies a readable scalar object in
     * this group.
     *
     * @param arc An OID arc.
     *
     * @return <CODE>true if `arc' leads to a readable variable.
     */
    public abstract boolean      isReadable(long arc);


    /**
     * Gets the table identified by the given `arc'.
     *
     * @param arc An OID arc.
     *
     * @return The <CODE>SnmpMibTable identified by `arc', or
     *    <CODE>null if `arc' does not identify any table.
     */
    public abstract SnmpMibTable getTable(long arc);

    /**
     * Checks whether the given OID arc identifies a variable (scalar
     * object).
     *
     * @exception If the given `arc' does not identify any variable in this
     *    group, throws an SnmpStatusException.
     */
    public void validateVarId(long arc, Object userData)
        throws SnmpStatusException {
        if (isVariable(arc) == false) {
            throw new SnmpStatusException(SnmpStatusException.noSuchObject);
        }
    }


    // -------------------------------------------------------------------
    // We use a hashtable (subgroup) in order to determine whether an
    // OID arc leads to a subgroup. This implementation can be changed if
    // needed...
    // For instance, the subclass could provide a generated isNestedArc()
    // method in which the subgroup OID arcs would be hardcoded.
    // However, the generic approach was preferred because at this time
    // groups and subgroups are dynamically registered in the MIB.
    //
    /**
     * Tell whether the given OID arc identifies a sub-tree
     * leading to a nested SNMP sub-group. This method is used internally.
     * You shouldn't need to call it directly.
     *
     * @param arc An OID arc.
     *
     * @return <CODE>true if the given OID arc identifies a subtree
     * leading to a nested SNMP sub-group.
     *
     */
    public boolean isNestedArc(long arc) {
        if (subgroups == null) return false;
        Object obj = subgroups.get(new Long(arc));
        // if the arc is registered in the hashtable,
        // it leads to a subgroup.
        return (obj != null);
    }

    /**
     * Generic handling of the <CODE>get operation.
     * <p>The actual implementation of this method will be generated
     * by mibgen. Usually, this implementation only delegates the
     * job to some other provided runtime class, which knows how to
     * access the MBean. The current toolkit thus provides two
     * implementations:
     * <ul>
The standard implementation will directly access the
     *         MBean through a java reference,</li>
     *     <li>The generic implementation will access the MBean through
     *         the MBean server.</li>
     * </ul>
     * <p>Both implementations rely upon specific - and distinct, set of
     * mibgen generated methods.
     * <p> You can override this method if you need to implement some
     * specific policies for minimizing the accesses made to some remote
     * underlying resources.
     * <p>
     *
     * @param req   The sub-request that must be handled by this node.
     *
     * @param depth The depth reached in the OID tree.
     *
     * @exception SnmpStatusException An error occurred while accessing
     *  the MIB node.
     */
    @Override
    abstract public void get(SnmpMibSubRequest req, int depth)
        throws SnmpStatusException;

    /**
     * Generic handling of the <CODE>set operation.
     * <p>The actual implementation of this method will be generated
     * by mibgen. Usually, this implementation only delegates the
     * job to some other provided runtime class, which knows how to
     * access the MBean. The current toolkit thus provides two
     * implementations:
     * <ul>
The standard implementation will directly access the
     *         MBean through a java reference,</li>
     *     <li>The generic implementation will access the MBean through
     *         the MBean server.</li>
     * </ul>
     * <p>Both implementations rely upon specific - and distinct, set of
     * mibgen generated methods.
     * <p> You can override this method if you need to implement some
     * specific policies for minimizing the accesses made to some remote
     * underlying resources.
     * <p>
     *
     * @param req   The sub-request that must be handled by this node.
     *
     * @param depth The depth reached in the OID tree.
     *
     * @exception SnmpStatusException An error occurred while accessing
     *  the MIB node.
     */
    @Override
    abstract public void set(SnmpMibSubRequest req, int depth)
        throws SnmpStatusException;

    /**
     * Generic handling of the <CODE>check operation.
     *
     * <p>The actual implementation of this method will be generated
     * by mibgen. Usually, this implementation only delegates the
     * job to some other provided runtime class, which knows how to
     * access the MBean. The current toolkit thus provides two
     * implementations:
     * <ul>
The standard implementation will directly access the
     *         MBean through a java reference,</li>
     *     <li>The generic implementation will access the MBean through
     *         the MBean server.</li>
     * </ul>
     * <p>Both implementations rely upon specific - and distinct, set of
     * mibgen generated methods.
     * <p> You can override this method if you need to implement some
     * specific policies for minimizing the accesses made to some remote
     * underlying resources, or if you need to implement some consistency
     * checks between the different values provided in the varbind list.
     * <p>
     *
     * @param req   The sub-request that must be handled by this node.
     *
     * @param depth The depth reached in the OID tree.
     *
     * @exception SnmpStatusException An error occurred while accessing
     *  the MIB node.
     */
    @Override
    abstract public void check(SnmpMibSubRequest req, int depth)
        throws SnmpStatusException;

    // --------------------------------------------------------------------
    // If we reach this node, we are below the root OID, so we just
    // return.
    // --------------------------------------------------------------------
    @Override
    public void getRootOid(Vector<Integer> result) {
    }

    // -------------------------------------------------------------------
    // PACKAGE METHODS
    // -------------------------------------------------------------------

    // -------------------------------------------------------------------
    // This method can also be overriden in a subclass to provide a
    // different implementation of the isNestedArc() method.
    // => if isNestedArc() is hardcoded, then registerSubArc() becomes
    //    useless and can become empty.
    /**
     * Register an OID arc that identifies a sub-tree
     * leading to a nested SNMP sub-group. This method is used internally.
     * You shouldn't ever call it directly.
     *
     * @param arc An OID arc.
     *
     */
    void registerNestedArc(long arc) {
        Long obj = new Long(arc);
        if (subgroups == null) subgroups = new Hashtable<>();
        // registers the arc in the hashtable.
        subgroups.put(obj,obj);
    }

    // -------------------------------------------------------------------
    // The SnmpMibOid algorithm relies on the fact that for every arc
    // registered in varList, there is a corresponding node at the same
    // position in children.
    // So the trick is to register a null node in children for each variable
    // in varList, so that the real subgroup nodes can be inserted at the
    // correct location.
    // registerObject() should be called for each scalar object and each
    // table arc by the generated subclass.
    /**
     * Register an OID arc that identifies a scalar object or a table.
     * This method is used internally. You shouldn't ever call it directly.
     *
     * @param arc An OID arc.
     *
     */
    protected void registerObject(long arc)
        throws IllegalAccessException {

        // this will register the variable in both varList and children
        // The node registered in children will be null, so that the parent
        // algorithm will behave as if no node were registered. This is a
        // trick that makes the parent algorithm behave as if only subgroups
        // were registered in varList and children.
        long[] oid = new long[1];
        oid[0] = arc;
        super.registerNode(oid,0,null);
    }

    // -------------------------------------------------------------------
    // registerNode() will be called at runtime when nested groups are
    // registered in the MIB. So we do know that this method will only
    // be called to register nested-groups.
    // We trap registerNode() in order to call registerSubArc()
    /**
     * Register a child node of this node in the OID tree.
     * This method is used internally. You shouldn't ever call it directly.
     *
     * @param oid The oid of the node being registered.
     * @param cursor The position reached in the oid.
     * @param node The node being registered.
     *
     */
    @Override
    void registerNode(long[] oid, int cursor ,SnmpMibNode node)
        throws IllegalAccessException {
        super.registerNode(oid,cursor,node);
        if (cursor < 0) return;
        if (cursor >= oid.length) return;
        // if we get here, then it means we are registering a subgroup.
        // We will thus register the sub arc in the subgroups hashtable.
        registerNestedArc(oid[cursor]);
    }

    // -------------------------------------------------------------------
    // see comments in SnmpMibNode
    // -------------------------------------------------------------------
    @Override
    void findHandlingNode(SnmpVarBind varbind,
                          long[] oid, int depth,
                          SnmpRequestTree handlers)
        throws SnmpStatusException {

        int length = oid.length;

        if (handlers == null)
            throw new SnmpStatusException(SnmpStatusException.snmpRspGenErr);

        final Object data = handlers.getUserData();

        if (depth >= length) {
            // Nothing is left... the oid is not valid
            throw new SnmpStatusException(SnmpStatusException.noAccess);
        }

        long arc = oid[depth];

        if (isNestedArc(arc)) {
            // This arc leads to a subgroup: delegates the search to the
            // method defined in SnmpMibOid
            super.findHandlingNode(varbind,oid,depth,handlers);
        } else if (isTable(arc)) {
            // This arc leads to a table: forward the search to the table.

            // Gets the table
            SnmpMibTable table = getTable(arc);

            // Forward the search to the table
            table.findHandlingNode(varbind,oid,depth+1,handlers);

        } else {
            // If it's not a variable, throws an exception
            validateVarId(arc, data);

            // The trailing .0 is missing in the OID
            if (depth+2 > length) {
                throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
            }

            // There are too many arcs left in the OID (there should remain
            // a single trailing .0)
            if (depth+2 < length) {
                throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
            }

            // The last trailing arc is not .0
            if (oid[depth+1] != 0L) {
                throw new SnmpStatusException(SnmpStatusException.noSuchInstance);
            }

            // It's one of our variable, register this node.
            handlers.add(this,depth,varbind);
        }
    }

    // -------------------------------------------------------------------
    // See comments in SnmpMibNode.
    // -------------------------------------------------------------------
    @Override
    long[] findNextHandlingNode(SnmpVarBind varbind,
                                long[] oid, int pos, int depth,
                                SnmpRequestTree handlers, AcmChecker checker)
        throws SnmpStatusException {

        int length = oid.length;
        SnmpMibNode node = null;

        if (handlers == null) {
            // This should be considered as a genErr, but we do not want to
            // abort the whole request, so we're going to throw
            // a noSuchObject...
            //
            throw new SnmpStatusException(SnmpStatusException.noSuchObject);
        }

        final Object data = handlers.getUserData();
        final int pduVersion = handlers.getRequestPduVersion();


        // The generic case where the end of the OID has been reached is
        // handled in the superclass
        // XXX Revisit: this works but it is somewhat convoluted. Just setting
        //              arc to -1 would work too.
        if (pos >= length)
            return super.findNextHandlingNode(varbind,oid,pos,depth,
                                              handlers, checker);

        // Ok, we've got the arc.
        long arc = oid[pos];

        long[] result = null;

        // We have a recursive logic. Should we have a loop instead?
        try {

            if (isTable(arc)) {
                // If the arc identifies a table, then we need to forward
                // the search to the table.

                // Gets the table identified by `arc'
                SnmpMibTable table = getTable(arc);

                // Forward to the table
                checker.add(depth, arc);
                try {
                    result = table.findNextHandlingNode(varbind,oid,pos+1,
                                                        depth+1,handlers,
                                                        checker);
                }catch(SnmpStatusException ex) {
                    throw new SnmpStatusException(SnmpStatusException.noSuchObject);
                } finally {
                    checker.remove(depth);
                }
                // Build up the leaf OID
                result[depth] = arc;
                return result;
            } else if (isReadable(arc)) {
                // If the arc identifies a readable variable, then two cases:

                if (pos == (length - 1)) {
                    // The end of the OID is reached, so we return the leaf
                    // corresponding to the variable identified by `arc'

                    // Build up the OID
                    // result = new SnmpOid(0);
                    // result.insert((int)arc);
                    result = new long[depth+2];
                    result[depth+1] = 0L;
                    result[depth] = arc;

                    checker.add(depth, result, depth, 2);
                    try {
                        checker.checkCurrentOid();
                    } catch(SnmpStatusException e) {
                        throw new SnmpStatusException(SnmpStatusException.noSuchObject);
                    } finally {
                        checker.remove(depth,2);
                    }

                    // Registers this node
                    handlers.add(this,depth,varbind);
                    return result;
                }

                // The end of the OID is not yet reached, so we must return
                // the next leaf following the variable identified by `arc'.
                // We cannot return the variable because whatever follows in
                // the OID will be greater or equals to 0, and 0 identifies
                // the variable itself - so we have indeed to return the
                // next object.
                // So we do nothing, because this case is handled at the
                // end of the if ... else if ... else ... block.

            } else if (isNestedArc(arc)) {
                // Now if the arc leads to a subgroup, we delegate the
                // search to the child, just as done in SnmpMibNode.
                //

                // get the child ( = nested arc node).
                //
                final SnmpMibNode child = getChild(arc);

                if (child != null) {
                    checker.add(depth, arc);
                    try {
                        result = child.findNextHandlingNode(varbind,oid,pos+1,
                                                            depth+1,handlers,
                                                            checker);
                        result[depth] = arc;
                        return result;
                    } finally {
                        checker.remove(depth);
                    }
                }
            }

            // The oid is not valid, we will throw an exception in order
            // to try with the next valid identifier...
            //
            throw new SnmpStatusException(SnmpStatusException.noSuchObject);

        } catch (SnmpStatusException e) {
            // We didn't find anything at the given arc, so we're going
            // to try with the next valid arc
            //
            long[] newOid = new long[1];
            newOid[0] = getNextVarId(arc,data,pduVersion);
            return findNextHandlingNode(varbind,newOid,0,depth,
                                        handlers,checker);
        }
    }

}