octetstring.java

snmp4j

/*_############################################################################
  _##
  _##  SNMP4J - OctetString.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.smi;

import java.io.*;
import java.util.*;
import org.snmp4j.asn1.BER;
import org.snmp4j.asn1.BERInputStream;

/**
 * The <code>OctetString</code> class represents the SMI type OCTET STRING.
 *
 * @author Frank Fock
 * @version 1.2
 */
public class OctetString extends Variable {

  static final long serialVersionUID = 4125661211046256289L;

  private static final char DEFAULT_HEX_DELIMITER = ':';

  private byte[] value = new byte[0];

  /**
   * Creates a zero length octet string.
   */
  public OctetString() {
  }

  /**
   * Creates an octet string from an byte array.
   * @param rawValue
   *    an array of bytes.
   */
  public OctetString(byte[] rawValue) {
    this(rawValue, 0, rawValue.length);
  }

  /**
   * Creates an octet string from an byte array.
   * @param rawValue
   *    an array of bytes.
   * @param offset
   *    the position (zero based) of the first byte to be copied from
   *    <code>rawValue</code>into the new <code>OctetSring</code>.
   * @param length
   *    the number of bytes to be copied.
   */
  public OctetString(byte[] rawValue, int offset, int length) {
    value = new byte[length];
    System.arraycopy(rawValue, offset, value, 0, length);
  }

  /**
   * Creates an octet string from a java string.
   *
   * @param stringValue
   *    a Java string.
   */
  public OctetString(String stringValue) {
    this.value = stringValue.getBytes();
  }

  /**
   * Creates an octet string from another OctetString by cloning its value.
   *
   * @param other
   *    an <code>OctetString</code> instance.
   */
  public OctetString(OctetString other) {
    this.value = new byte[0];
    append(other);
  }

  /**
   * Appends a single byte to this octet string.
   * @param b
   *    a byte value.
   */
  public void append(byte b) {
    byte[] newValue = new byte[value.length+1];
    System.arraycopy(value, 0, newValue, 0, value.length);
    newValue[value.length] = b;
    value = newValue;
  }

  /**
   * Appends an array of bytes to this octet string.
   * @param bytes
   *    an array of bytes.
   */
  public void append(byte[] bytes) {
    byte[] newValue = new byte[value.length + bytes.length];
    System.arraycopy(value, 0, newValue, 0, value.length);
    System.arraycopy(bytes, 0, newValue, value.length, bytes.length);
    value = newValue;
  }

  /**
   * Appends an octet string.
   * @param octetString
   *   an <code>OctetString</code> to append to this octet string.
   */
  public void append(OctetString octetString) {
    append(octetString.getValue());
  }

  /**
   * Appends the supplied string to this <code>OctetString</code>. Calling this
   * method is identical to <I>append(string.getBytes())</I>.
   * @param string
   *    a String instance.
   */
  public void append(String string) {
    append(string.getBytes());
  }

  /**
   * Sets the value of the octet string to a zero length string.
   */
  public void clear() {
    value = new byte[0];
  }

  public void encodeBER(OutputStream outputStream) throws java.io.IOException {
    BER.encodeString(outputStream, BER.OCTETSTRING, getValue());
  }

  public void decodeBER(BERInputStream inputStream) throws java.io.IOException {
    BER.MutableByte type = new BER.MutableByte();
    byte[] v = BER.decodeString(inputStream, type);
    if (type.getValue() != (BER.ASN_UNIVERSAL | 0x04)) {
      throw new IOException("Wrong type encountered when decoding OctetString: "+type.getValue());
    }
    setValue(v);
  }

  public int getBERLength() {
    return value.length + BER.getBERLengthOfLength(value.length) + 1;
  }

  public int getSyntax() {
    return SMIConstants.SYNTAX_OCTET_STRING;
  }

  /**
   * Gets the byte at the specified index.
   * @param index
   *    a zero-based index into the octet string.
   * @return
   *    the byte value at the specified index.
   * @throws ArrayIndexOutOfBoundsException
   *    if <code>index</code> &lt; 0 or &gt; {@link #length()}.
   */
  public byte get(int index) {
    return value[index];
  }

  /**
   * Sets the byte value at the specified index.
   * @param index
   *    an index value greater or equal 0 and less than {@link #length()}.
   * @param b
   *    the byte value to set.
   * @since v1.2
   */
  public void set(int index, byte b) {
    value[index] = b;
  }

  public int hashCode() {
    int hash = 0;
    for (int i=0; i<value.length; i++) {
      hash += value[i]*31^((value.length-1)-i);
    }
    return hash;
  }

  public boolean equals(Object o) {
    if (o instanceof OctetString) {
      OctetString other = (OctetString)o;
      return Arrays.equals(value, other.value);
    }
    else if (o instanceof byte[]) {
      return Arrays.equals(value, (byte[])o);
    }
    return false;
  }

  public int compareTo(Object o) {
    if (o instanceof OctetString) {
      OctetString other = (OctetString)o;
      int maxlen = Math.min(value.length, other.value.length);
      for (int i=0; i<maxlen; i++) {
        if (value[i] != other.value[i]) {
          if ((value[i] & 0xFF) < (other.value[i] & 0xFF)) {
            return -1;
          }
          else {
            return 1;
          }
        }
      }
      return (value.length - other.value.length);
    }
    throw new ClassCastException(o.getClass().getName());
  }

  /**
   * Returns a new string that is a substring of this string. The substring
   * begins at the specified <code>beginIndex</code> and extends to the
   * character at index <code>endIndex - 1</code>.
   * Thus the length of the substring is <code>endIndex-beginIndex</code>.
   * @param beginIndex
   *    the beginning index, inclusive.
   * @param endIndex
   *    the ending index, exclusive.
   * @return
   *    the specified substring.
   * @since 1.3
   */
  public OctetString substring(int beginIndex, int endIndex) {
    if ((beginIndex < 0) || (endIndex > length())) {
      /**@todo Implement better exception message */
      new IndexOutOfBoundsException();
    }
    byte[] substring = new byte[endIndex - beginIndex];
    System.arraycopy(value, beginIndex, substring, 0, substring.length);
    return new OctetString(substring);
  }

  /**
   * Tests if this octet string starts with the specified prefix.
   * @param prefix
   *    the prefix.
   * @return
   *    <code>true</code> if the bytes of this octet string up to the length
   *    of <code>prefix</code> equal those of <code>prefix</code>.
   * @since 1.2
   */
  public boolean startsWith(OctetString prefix) {
    if ((prefix == null) || prefix.length() < length()) {
      return false;
    }
    for (int i=0; i<prefix.length(); i++) {
      if (prefix.get(i) != value[i]) {
        return false;
      }
    }
    return true;
  }

  /**
   * Determines whether this octet string contains non ISO control characters
   * only.
   * @return
   *    <code>false</code> if this octet string contains any ISO control
   *    characters as defined by <code>Character.isISOControl(char)</code>.
   */
  public boolean isPrintable() {
    for (int i=0; i<value.length; i++) {
      if (Character.isISOControl((char)value[i])) {
        return false;
      }
    }
    return true;
  }

  public String toString() {
    if (isPrintable()) {
      return new String(value);
    }
    return toHexString();
  }

  public String toHexString() {
    return toHexString(DEFAULT_HEX_DELIMITER);
  }

  public static OctetString fromHexString(String hexString) {
    return fromHexString(hexString, DEFAULT_HEX_DELIMITER);
  }

  public static OctetString fromHexString(String hexString, char delimiter) {
    return OctetString.fromString(hexString, delimiter, 16);
  }

  public static OctetString fromString(String string, char delimiter, int radix) {
    String delim = "";
    delim += delimiter;
    StringTokenizer st = new StringTokenizer(string, delim);
    byte[] value = new byte[st.countTokens()];
    for (int n=0; st.hasMoreTokens(); n++) {
      String s = st.nextToken();
      value[n] = (byte)Integer.parseInt(s, radix);
    }
    return new OctetString(value);
  }

  public String toString(char separator, int radix) {
    int digits = (int)(Math.round((float)Math.log(256)/Math.log(radix)));
    StringBuffer buf = new StringBuffer(value.length*(digits+1));
    for (int i=0; i<value.length; i++) {
      if (i > 0) {
        buf.append(separator);
      }
      int v = (value[i] & 0xFF);
      String val = Integer.toString(v, radix);
      for (int j=0; j < digits - val.length(); j++) {
        buf.append('0');
      }
      buf.append(val);
    }
    return buf.toString();
  }

  public String toHexString(char separator) {
    return toString(separator, 16);
  }

  public void setValue(byte[] value) {
    if (value == null) {
      throw new IllegalArgumentException(
          "OctetString must not be assigned a null value");
    }
    this.value = value;
  }

  public byte[] getValue() {
    return value;
  }

  /**
   * Gets the length of the byte string.
   * @return
   *    an integer >= 0.
   */
  public int length() {
    return value.length;
  }

  public Object clone() {
    return new OctetString(value);
  }

  /**
   * Returns the length of the payload of this <code>BERSerializable</code>
   * object in bytes when encoded according to the Basic Encoding Rules (BER).
   *
   * @return the BER encoded length of this variable.
   */
  public int getBERPayloadLength() {
    return value.length;
  }

}