SnmpMibNode


1   /*
2    * @(#)file      SnmpMibNode.java
3    * @(#)author    Sun Microsystems, Inc.
4    * @(#)version   4.20
5    * @(#)date      08/02/09
6    *
7    * Copyright 2004 Sun Microsystems, Inc. All rights reserved.
8    * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
9    *
10   */
11  
12  
13  package com.sun.jmx.snmp.agent;
14  
15  
16  
17  // java imports
18  //
19  import java.io.Serializable  ;
20  import java.util.Vector  ;
21  import java.util.Hashtable  ;
22  import java.util.Enumeration  ;
23  
24  // jmx imports
25  //
26  import com.sun.jmx.snmp.SnmpOid;
27  import com.sun.jmx.snmp.SnmpValue;
28  import com.sun.jmx.snmp.SnmpVarBind;
29  import com.sun.jmx.snmp.SnmpDefinitions;
30  import com.sun.jmx.snmp.SnmpStatusException;
31  
32  /**
33   * The <CODE>SnmpMibNode</CODE> class represents a node in an SNMP MIB.
34   * <P>
35   * This class is used internally and by the class generated by 
36   * <CODE>mibgen</CODE>.
37   * You should not need to use this class directly.
38   *
39   * <p><b>This API is a Sun Microsystems internal API  and is subject 
40   * to change without notice.</b></p>
41   * @version     4.20     12/19/03
42   * @author      Sun Microsystems, Inc
43   */
44  
45  public abstract class SnmpMibNode implements Serializable   {
46      
47      // ---------------------------------------------------------------------
48      // PUBLIC METHODS
49      //----------------------------------------------------------------------
50    
51      /**
52       * Get the next OID arc corresponding to a readable scalar variable, 
53       * a branch leading to a subgroub, or a table.
54       *
55       * @param id Id we start from looking for the next.
56       * @param userData A contextual object containing user-data.
57       *        This object is allocated through the <code>
58       *        {@link com.sun.jmx.snmp.agent.SnmpUserDataFactory}</code>
59       *        for each incoming SNMP request.
60       *
61       * @return The next id in this group.
62       *
63       * @exception SnmpStatusException If no id is found after the given id.
64       */
65      public long getNextVarId(long id, Object   userData)  
66      throws SnmpStatusException {
67      return getNextIdentifier(varList,id);
68      }
69  
70      /**
71       * Get the next OID arc corresponding to a readable scalar variable, 
72       * a branch leading to a subgroub, or a table, possibly skipping over
73       * those arcs that must not or cannot be returned.
74       *
75       * Calls {@link #getNextVarId(long,java.lang.Object)} until
76       * {@link #skipVariable(long,java.lang.Object,int)} returns false.
77       *
78       * @param id Id we start from looking for the next.
79       * @param userData A contextual object containing user-data.
80       *        This object is allocated through the <code>
81       *        {@link com.sun.jmx.snmp.agent.SnmpUserDataFactory}</code>
82       *        for each incoming SNMP request.
83       * @param pduVersion Protocol version of the original request PDU.
84       *
85       * @return The next id in this group which can be returned using
86       *         the given PDU's protocol version.
87       *
88       * @exception SnmpStatusException If no id is found after the given id.
89       */
90      public long getNextVarId(long id, Object   userData, int pduVersion)  
91      throws SnmpStatusException {
92      long varid=id;
93      do {
94          varid = getNextVarId(varid,userData);
95      } while (skipVariable(varid,userData,pduVersion));
96  
97      return varid;
98      }
99          
100     /**
101      * Hook for subclasses. 
102      * The default implementation of this method is to always return
103      * false. Subclasses should redefine this method so that it returns
104      * true when:
105      * <ul><li>the variable is a leaf that is not instantiated,</li>
106      * <li>or the variable is a leaf whose type cannot be returned by that
107      *     version of the protocol (e.g. an Counter64 with SNMPv1).</li>
108      * </ul>
109      *
110      * @param id Id we start from looking for the next.
111      * @param userData A contextual object containing user-data.
112      *        This object is allocated through the <code>
113      *        {@link com.sun.jmx.snmp.agent.SnmpUserDataFactory}</code>
114      *        for each incoming SNMP request.
115      * @param pduVersion Protocol version of the original request PDU.
116      *
117      * @return true if the variable must be skipped by the get-next
118      *         algorithm.
119      */
120     protected boolean skipVariable(long id, Object   userData, int pduVersion) {
121     return false;
122     }
123 
124     /**
125      * Find the node which handles a varbind, and register it in the
126      * SnmpRequestTree. This method is a pure internal method. You should
127      * never try to call it directly.
128      *
129      * @param varbind  The varbind to be handled
130      *
131      * @param oid      The OID array extracted from the varbind
132      *
133      * @param depth    The depth reached in the OID at this step of the
134      *                 processing.
135      *
136      * @param handlers The Hashtable in which the varbind will be registered
137      *                 with its handling node. This hashtable contains 
138      *                 <CODE>SnmpRequestTree.Handler</CODE> items.
139      *
140      * @exception SnmpStatusException No handling node was found.
141      **/
142     void findHandlingNode(SnmpVarBind varbind, 
143               long[] oid, int depth, 
144               SnmpRequestTree handlers)
145     throws SnmpStatusException {
146     throw noSuchObjectException;
147     }
148 
149     /**
150      * Find the node which handles the leaf that immediately follows the
151      * given varbind OID, and register the it in the SnmpRequestTree.
152      * This method is a pure internal method. You should never try to call
153      * it directly.
154      *
155      * @param varbind  The varbind to be handled
156      *
157      * @param oid      The OID array extracted from the varbind
158      *
159      * @param depth    The depth reached in the OID at this step of the
160      *                 processing.
161      * 
162      * @param handlers The Hashtable in which the varbind will be registered
163      *                 with its handling node. This hashtable contains 
164      *                 SnmpRequestTree.Handler items.
165      *
166      * @return The SnmpOid of the next leaf.
167      *
168      * @exception SnmpStatusException No handling node was found.
169      **/
170     long[] findNextHandlingNode(SnmpVarBind varbind, 
171                  long[] oid, int pos, int depth, 
172                  SnmpRequestTree handlers, AcmChecker checker) 
173     throws SnmpStatusException {
174     throw noSuchObjectException;
175     }
176 
177     /**
178      * Generic handling of the <CODE>get</CODE> operation.
179      *
180      * <p> You can override this method if you need to implement some
181      * specific policies for minimizing the accesses made to some remote
182      * underlying resources.
183      * <p>
184      *
185      * @param req   The sub-request that must be handled by this node.
186      *
187      * @param depth The depth reached in the OID tree.
188      *
189      * @exception SnmpStatusException An error occurred while accessing 
190      *  the MIB node.
191      */
192     public abstract void get(SnmpMibSubRequest req, int depth) 
193     throws SnmpStatusException;
194 
195     /**
196      * Generic handling of the <CODE>set</CODE> operation.
197      * <p> You can override this method if you need to implement some
198      * specific policies for minimizing the accesses made to some remote
199      * underlying resources.
200      * <p>
201      *
202      * @param req   The sub-request that must be handled by this node.
203      *
204      * @param depth The depth reached in the OID tree.
205      *
206      * @exception SnmpStatusException An error occurred while accessing 
207      *  the MIB node.
208      */
209     public abstract void set(SnmpMibSubRequest req, int depth) 
210     throws SnmpStatusException;
211 
212     /**
213      * Generic handling of the <CODE>check</CODE> operation.
214      * <p> You can override this method if you need to implement some
215      * specific policies for minimizing the accesses made to some remote
216      * underlying resources, or if you need to implement some consistency
217      * checks between the different values provided in the varbind list.
218      * <p>
219      *
220      * @param req   The sub-request that must be handled by this node.
221      *
222      * @param depth The depth reached in the OID tree.
223      *
224      * @exception SnmpStatusException An error occurred while accessing 
225      *  the MIB node.
226      */
227     public abstract void check(SnmpMibSubRequest req, int depth) 
228     throws SnmpStatusException;
229 
230     /**
231      * Sorts the specified integer array.
232      *
233      * @param array An integer array.
234      */
235     static public void sort(int array[]) {
236         QuickSort(array, 0, array.length - 1);
237     }
238     
239     /**
240      * Computes the root OID of the MIB.
241      */
242     public void getRootOid(Vector   result) {
243         return;
244     }
245     
246     //----------------------------------------------------------------------
247     // PACKAGE METHODS
248     //----------------------------------------------------------------------
249     
250     /**
251      * This is a generic version of C.A.R Hoare's Quick Sort
252      * algorithm.  This will handle arrays that are already
253      * sorted, and arrays with duplicate keys.
254      *
255      * If you think of a one dimensional array as going from
256      * the lowest index on the left to the highest index on the right
257      * then the parameters to this function are lowest index or
258      * left and highest index or right.  The first time you call
259      * this function it will be with the parameters 0, a.length - 1.
260      *
261      * @param a An integer array.
262      * @param lo0 Left boundary of array partition.
263      * @param hi0 Right boundary of array partition.
264      */
265     static void QuickSort(int a[], int lo0, int hi0) {
266         int lo = lo0;
267         int hi = hi0;
268         int mid;
269 
270         if ( hi0 > lo0) {  
271 
272             /* Arbitrarily establishing partition element as the midpoint of
273              * the array.
274              */
275             mid = a[ ( lo0 + hi0 ) / 2 ];
276 
277             // loop through the array until indices cross
278             while( lo <= hi ) {
279                 /* find the first element that is greater than or equal to
280                  * the partition element starting from the left Index.
281                  */
282                 while( ( lo < hi0 )  && ( a[lo] < mid ))
283                     ++lo;
284 
285                 /* find an element that is smaller than or equal to
286                  * the partition element starting from the right Index.
287                  */
288                 while( ( hi > lo0 ) && ( a[hi] > mid ))
289                     --hi;
290 
291                 // if the indexes have not crossed, swap
292                 if( lo <= hi ) {
293                     swap(a, lo, hi);
294                     ++lo;
295                     --hi;
296                 }
297             }
298 
299             /* If the right index has not reached the left side of array
300              * must now sort the left partition.
301              */
302             if( lo0 < hi )
303                 QuickSort( a, lo0, hi );
304 
305             /* If the left index has not reached the right side of array
306              * must now sort the right partition.
307              */
308             if( lo < hi0 )
309                 QuickSort( a, lo, hi0 );
310 
311         }  
312     }   
313 
314     //----------------------------------------------------------------------
315     // PROTECTED METHODS
316     //----------------------------------------------------------------------
317     
318     /**
319      * This will give the first element greater than <CODE>value</CODE> 
320      * in a sorted array.
321      * If there is no element of the array greater than <CODE>value</CODE>,
322      * the method will throw a <CODE>SnmpStatusException</CODE>.
323      *
324      * @param table A sorted integer array.
325      *
326      * @param value The greatest value.
327      *
328      * @exception SnmpStatusException If there is no element greater than
329      *     <CODE>value</CODE>.
330      */
331     final static protected int getNextIdentifier(int table[], long value) 
332     throws SnmpStatusException {
333  
334     final int[] a = table;
335         final int val= (int) value;
336 
337     if (a == null) 
338         throw noSuchObjectException;
339 
340         int low= 0;
341         int max= a.length;
342         int curr= low + (max-low)/2;
343         int elmt= 0;
344     
345         // Basic check
346         //
347     if (max < 1) 
348         throw noSuchObjectException;
349 
350         if (a[max-1] <= val) 
351             throw noSuchObjectException;
352  
353         while (low <= max) {
354             elmt= a[curr];     
355             if (val == elmt) {
356                 // We ned to get the next index ...
357                 //
358                 curr++;
359                 return a[curr];
360             }
361             if (elmt < val) {
362                 low= curr +1;
363             } else {
364                 max= curr -1;
365             }
366             curr= low + (max-low)/2;
367         }
368         return a[curr];
369     }  
370 
371     
372     //----------------------------------------------------------------------
373     // PRIVATE METHODS
374     //----------------------------------------------------------------------
375     
376     final static private void swap(int a[], int i, int j) {
377         int T;
378         T = a[i];
379         a[i] = a[j];
380         a[j] = T;
381     }
382     
383     //----------------------------------------------------------------------
384     // PROTECTED VARIABLES
385     //----------------------------------------------------------------------
386     
387     /**
388      * Contains the list of variable identifiers.
389      */
390     protected int[] varList;
391 
392     /**
393      * Contains a predefined exception that is often fired when an 
394      * object is not found in the MIB.
395      */
396     static final protected SnmpStatusException noSuchInstanceException =
397         new SnmpStatusException(SnmpStatusException.noSuchInstance);
398     static final protected SnmpStatusException noSuchObjectException =
399         new SnmpStatusException(SnmpStatusException.noSuchObject);
400     static final protected SnmpStatusException noSuchNameException =
401         new SnmpStatusException(SnmpDefinitions.snmpRspNoSuchName);
402 }
403
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