/*_############################################################################  _##  _##  SNMP4J - PDU.java  _##  _##  Copyright 2003-2005  Frank Fock and Jochen Katz (SNMP4J.org)  _##  _##  Licensed under the Apache License, Version 2.0 (the "License");  _##  you may not use this file except in compliance with the License.  _##  You may obtain a copy of the License at  _##  _##      http://www.apache.org/licenses/LICENSE-2.0  _##  _##  Unless required by applicable law or agreed to in writing, software  _##  distributed under the License is distributed on an "AS IS" BASIS,  _##  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  _##  See the License for the specific language governing permissions and  _##  limitations under the License.  _##  _##########################################################################*/package org.snmp4j;import org.snmp4j.smi.*;import org.snmp4j.asn1.*;import java.io.IOException;import java.io.OutputStream;import java.util.Vector;import org.snmp4j.smi.Integer32;import org.snmp4j.mp.SnmpConstants;/** * The <code>PDU</code> class represents a SNMP protocol data unit. The PDU * version supported by the BER decoding and encoding methods of this class * is v2. * <p> * The default PDU type is GET. * * @author Frank Fock * @version 1.1 * @see PDUv1 * @see ScopedPDU */public class PDU implements BERSerializable {  /**   * Denotes a get PDU.   */  public static final int GET      = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x0);  /**   * Denotes a getnext (search) PDU.   */  public static final int GETNEXT  = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x1);  /**   * Denotes a response PDU.   */  public static final int RESPONSE = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x2);  /**   * Denotes a set PDU.   */  public static final int SET      = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x3);  /**   * Denotes a SNMPv1 trap PDU. This type can only be used with instances of the   * {@link PDUv1} class.   */  public static final int V1TRAP   = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x4);  /**   * Denotes a SNMPv2c/v3 getbulk PDU.   */  public static final int GETBULK  = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x5);  /**   * Denotes a SNMPv2c/v3 inform PDU (unprecisely also known as a confirmed   * notification).   */  public static final int INFORM   = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x6);  /**   * Denotes a SNMPv2c/v3 notification PDU (undistinguishable from   * {@link #TRAP}).   */  public static final int TRAP     = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x7);  /**   * Denotes a SNMPv2c/v3 notification PDU (undistinguishable from   * {@link #NOTIFICATION}).   */  public static final int NOTIFICATION = TRAP;  /**   * Denotes a SNMPv3 report PDU.   */  public static final int REPORT   = (BER.ASN_CONTEXT | BER.ASN_CONSTRUCTOR | 0x8);  // Error status constants  /**   * Operation success (no error).   */  public static final int noError = SnmpConstants.SNMP_ERROR_SUCCESS;  /**   * PDU encoding is too big for the transport used.   */  public static final int tooBig = SnmpConstants.SNMP_ERROR_TOO_BIG;  /**   * No such variable binding name, see error index.   */  public static final int noSuchName = SnmpConstants.SNMP_ERROR_NO_SUCH_NAME;  /**   * Bad value in variable binding, see error index.   */  public static final int badValue = SnmpConstants.SNMP_ERROR_BAD_VALUE;  /**   * The variable binding is read-only, see error index.   */  public static final int readOnly = SnmpConstants.SNMP_ERROR_READ_ONLY;  /**   * An unspecific error caused by a variable binding, see error index.   */  public static final int genErr = SnmpConstants.SNMP_ERROR_GENERAL_ERROR;  /**   * The variable binding is not accessible by the current MIB view, see error   * index.   */  public static final int noAccess = SnmpConstants.SNMP_ERROR_NO_ACCESS;  /**   * The variable binding's value has the wrong type, see error index.   */  public static final int wrongType = SnmpConstants.SNMP_ERROR_WRONG_TYPE;  /**   * The variable binding's value has the wrong length, see error index.   */  public static final int wrongLength = SnmpConstants.SNMP_ERROR_WRONG_LENGTH;  /**   * The variable binding's value has the wrong encoding, see error index.   */  public static final int wrongEncoding =      SnmpConstants.SNMP_ERROR_WRONG_ENCODING;  /**   * The specified object does not exists and cannot be created,   * see error index.   */  public static final int noCreation = SnmpConstants.SNMP_ERROR_NO_CREATION;  /**   * The variable binding's value is presently inconsistent with the current   * state of the target object, see error index.   */  public static final int inconsistentValue =      SnmpConstants.SNMP_ERROR_INCONSISTENT_VALUE;  /**   * The resource needed to assign a variable binding's value is presently   * unavailable, see error index.   */  public static final int resourceUnavailable =      SnmpConstants.SNMP_ERROR_RESOURCE_UNAVAILABLE;  /**   * Unable to commit a value, see error index.   */  public static final int commitFailed = SnmpConstants.SNMP_ERROR_COMMIT_FAILED;  /**   * Unable to undo a committed value, see error index.   */  public static final int undoFailed = SnmpConstants.SNMP_ERROR_UNDO_FAILED;  /**   * Unauthorized access, see error index.   */  public static final int authorizationError =      SnmpConstants.SNMP_ERROR_AUTHORIZATION_ERROR;  /**   * The variable's value cannot be modified, see error index.   */  public static final int notWritable = SnmpConstants.SNMP_ERROR_NOT_WRITEABLE;  /**   * The specified object does not exists and presently it cannot be created,   * see error index.   */  public static final int inconsistentName =      SnmpConstants.SNMP_ERROR_INCONSISTENT_NAME;  protected Vector variableBindings = new Vector();  protected Integer32 errorStatus = new Integer32();  protected Integer32 errorIndex = new Integer32();  protected Integer32 requestID = new Integer32();  protected int type = GET;  /**   * Default constructor.   */  public PDU() {  }  /**   * Copy constructor.   * @param other   *    the <code>PDU</code> to copy from.   */  public PDU(PDU other) {    variableBindings = (Vector) other.variableBindings.clone();    errorIndex = (Integer32) other.errorIndex.clone();    errorStatus = (Integer32) other.errorStatus.clone();    type = other.type;    requestID = (Integer32) other.requestID.clone();  }  /**   * Adds a variable binding to this PDU.   * @param vb   *   a <code>VariableBinding</code> instance.   */  public void add(VariableBinding vb) {    variableBindings.add(vb);  }  /**   * Adds an array of variable bindings to this PDU.   * @param vbs   *   an array of <code>VariableBinding</code> instances. The instances in the   *   array will be appended to the current list of variable bindings in the   *   PDU.   */  public void addAll(VariableBinding[] vbs) {    variableBindings.ensureCapacity(variableBindings.size()+vbs.length);    for (int i=0; i<vbs.length; i++) {      variableBindings.add(vbs[i]);    }  }  /**   * Gets the variable binding at the specified position.   * @param index   *    a zero based positive integer (<code>0 <= index < {@link #size()}</code>)   * @return   *    a VariableBinding instance. If <code>index</code> is out of bounds   *    an exception is thrown.   */  public VariableBinding get(int index) {    return (VariableBinding)variableBindings.get(index);  }  /**   * Sets the variable binding at the specified position.   * @param index   *    a zero based positive integer (<code>0 <= index < {@link #size()}</code>)   *    If <code>index</code> is out of bounds   *    an exception is thrown.   * @param vb   *    a VariableBinding instance (<code>null</code> is not allowed).   * @return   *    the variable binding that has been replaced.   */  public VariableBinding set(int index, VariableBinding vb) {    if (vb == null) {      throw new NullPointerException("Variable binding must not be null");    }    return (VariableBinding)variableBindings.set(index, vb);  }  /**   * Removes the variable binding at the supplied position.   * @param index   *    a position >= 0 and < {@link #size()}.   */  public void remove(int index) {    variableBindings.remove(index);  }  /**   * Gets the number of variable bindings in the PDU.   * @return   *    the size of the PDU.   */  public int size() {    return variableBindings.size();  }  /**   * Gets the variable binding vector.   * @return   *    the internal <code>Vector</code> containing the PDU's variable bindings.   */  public Vector getVariableBindings() {    return variableBindings;  }  /**   * Remove the last variable binding from the PDU, if such an element exists.   */  public void trim() {    if (variableBindings.size() > 0) {      variableBindings.removeElementAt(variableBindings.size() - 1);    }  }  /**   * Sets the error status of the PDU.   * @param errorStatus   *    a SNMP error status.   * @see SnmpConstants   */  public void setErrorStatus(int errorStatus) {    this.errorStatus.setValue(errorStatus);  }  /**   * Gets the error status of the PDU.   * @return   *    a SNMP error status.   * @see SnmpConstants   */  public int getErrorStatus() {    return errorStatus.getValue();  }  /**   * Gets a textual description of the error status.   * @return   *    a String containing an element of the   *    {@link SnmpConstants#SNMP_ERROR_MESSAGES} array for a valid error status.   *    "Unknown error: <errorStatusNumber>" is returned for any other value.   */  public String getErrorStatusText() {