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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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,

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 *

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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</CODE>.

 * You should not need to use this class directly.

 *

 * <p><b>This API is a Sun Microsystems internal API  and is subject

 * to change without notice.</b></p>

 */

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</CODE> 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</CODE> 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</CODE> 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</CODE> identified by `arc', or

     *    <CODE>null</CODE> 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 noSuchObjectException;

    }

    // -------------------------------------------------------------------

    // 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 prefered 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</CODE> 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</CODE> 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><li>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.

     */

    abstract public void get(SnmpMibSubRequest req, int depth)

        throws SnmpStatusException;

    /**

     * Generic handling of the <CODE>set</CODE> 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><li>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.

     */

    abstract public void set(SnmpMibSubRequest req, int depth)

        throws SnmpStatusException;

    /**

     * Generic handling of the <CODE>check</CODE> 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><li>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.

     */

    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.

    // --------------------------------------------------------------------

    }

    // -------------------------------------------------------------------

    // 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);

        // 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.

     *

     */

    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

    // -------------------------------------------------------------------

    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 noSuchInstanceException;

            // There are too many arcs left in the OID (there should remain

            // a single trailing .0)

            if (depth+2 < length)

                throw noSuchInstanceException;

            // The last trailing arc is not .0

            if (oid[depth+1] != 0L)

                throw noSuchInstanceException;

            // It's one of our variable, register this node.

            handlers.add(this,depth,varbind);

        }

    }

    // -------------------------------------------------------------------

    // See comments in SnmpMibNode.

    // -------------------------------------------------------------------

    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 noSuchObjectException;

        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 noSuchObjectException;

                } 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 noSuchObjectException;

                    } 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 noSuchObjectException;

        } 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);

        }

    }

}