/*
* @(#)file BerEncoder.java
* @(#)author Sun Microsystems, Inc.
* @(#)version 4.16
* @(#)date 05/08/26
*
* Copyright 2004 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*
*/
package com.sun.jmx.snmp;
/**
* The <CODE>BerEncoder</CODE> class is used for encoding data using BER.
*
* A <CODE>BerEncoder</CODE> needs to be set up with a byte buffer. The encoded
* data are stored in this byte buffer.
* <P>
* NOTE : the buffer is filled from end to start. This means the caller
* needs to encode its data in the reverse order.
*
*
* <p><b>This API is a Sun Microsystems internal API and is subject
* to change without notice.</b></p>
* @version 4.16 12/19/03
* @author Sun Microsystems, Inc
*
* @since 1.5
*/
public class BerEncoder {
/**
* Constructs a new encoder and attaches it to the specified byte string.
*
* @param b The byte string containing the encoded data.
*/
public BerEncoder(byte b[]) {
bytes = b ;
start = b.length ;
stackTop = 0 ;
}
/**
* Trim the encoding data and returns the length of the encoding.
*
* The encoder does backward encoding : so the bytes buffer is
* filled from end to start. The encoded data must be shift before
* the buffer can be used. This is the purpose of the <CODE>trim</CODE> method.
*
* After a call to the <CODE>trim</CODE> method, the encoder is reinitialized and <CODE>putXXX</CODE>
* overwrite any existing encoded data.
*
* @return The length of the encoded data.
*/
public int trim() {
final int result = bytes.length - start ;
// for (int i = start ; i < bytes.length ; i++) {
// bytes[i-start] = bytes[i] ;
// }
if (result > 0)
java.lang.System.arraycopy(bytes,start,bytes,0,result);
start = bytes.length ;
stackTop = 0 ;
return result ;
}
/**
* Put an integer.
*
* @param v The integer to encode.
*/
public void putInteger(int v) {
putInteger(v, IntegerTag) ;
}
/**
* Put an integer with the specified tag.
*
* @param v The integer to encode.
* @param tag The tag to encode.
*/
public void putInteger(int v, int tag) {
putIntegerValue(v) ;
putTag(tag) ;
}
/**
* Put an integer expressed as a long.
*
* @param v The long to encode.
*/
public void putInteger(long v) {
putInteger(v, IntegerTag) ;
}
/**
* Put an integer expressed as a long with the specified tag.
*
* @param v The long to encode
* @param tag The tag to encode.
*/
public void putInteger(long v, int tag) {
putIntegerValue(v) ;
putTag(tag) ;
}
/**
* Put an octet string.
*
* @param s The bytes to encode
*/
public void putOctetString(byte[] s) {
putOctetString(s, OctetStringTag) ;
}
/**
* Put an octet string with a specified tag.
*
* @param s The bytes to encode
* @param tag The tag to encode.
*/
public void putOctetString(byte[] s, int tag) {
putStringValue(s) ;
putTag(tag) ;
}
/**
* Put an object identifier.
*
* @param s The oid to encode.
*/
public void putOid(long[] s) {
putOid(s, OidTag) ;
}
/**
* Put an object identifier with a specified tag.
*
* @param s The integer to encode.
* @param tag The tag to encode.
*/
public void putOid(long[] s, int tag) {
putOidValue(s) ;
putTag(tag) ;
}
/**
* Put a <CODE>NULL</CODE> value.
*/
public void putNull() {
putNull(NullTag) ;
}
/**
* Put a <CODE>NULL</CODE> value with a specified tag.
*
* @param tag The tag to encode.
*/
public void putNull(int tag) {
putLength(0) ;
putTag(tag) ;
}
/**
* Put an <CODE>ANY</CODE> value. In fact, this method does not encode anything.
* It simply copies the specified bytes into the encoding.
*
* @param s The encoding of the <CODE>ANY</CODE> value.
*/
public void putAny(byte[] s) {
putAny(s, s.length) ;
}
/**
* Put an <CODE>ANY</CODE> value. Only the first <CODE>byteCount</CODE> are considered.
*
* @param s The encoding of the <CODE>ANY</CODE> value.
* @param byteCount The number of bytes of the encoding.
*/
public void putAny(byte[] s, int byteCount) {
java.lang.System.arraycopy(s,0,bytes,start-byteCount,byteCount);
start -= byteCount;
// for (int i = byteCount - 1 ; i >= 0 ; i--) {
// bytes[--start] = s[i] ;
// }
}
/**
* Open a sequence.
* The encoder push the current position on its stack.
*/
public void openSequence() {
stackBuf[stackTop++] = start ;
}
/**
* Close a sequence.
* The decode pull the stack to know the end of the current sequence.
*/
public void closeSequence() {
closeSequence(SequenceTag) ;
}
/**
* Close a sequence with the specified tag.
*/
public void closeSequence(int tag) {
final int end = stackBuf[--stackTop] ;
putLength(end - start) ;
putTag(tag) ;
}
//
// Some standard tags
//
public final static int BooleanTag = 1 ;
public final static int IntegerTag = 2 ;
public final static int OctetStringTag = 4 ;
public final static int NullTag = 5 ;
public final static int OidTag = 6 ;
public final static int SequenceTag = 0x30 ;
////////////////////////// PROTECTED ///////////////////////////////
/**
* Put a tag and move the current position backward.
*
* @param tag The tag to encode.
*/
protected final void putTag(int tag) {
if (tag < 256) {
bytes[--start] = (byte)tag ;
}
else {
while (tag != 0) {
bytes[--start] = (byte)(tag & 127) ;
tag = tag << 7 ;
}
}
}
/**
* Put a length and move the current position backward.
*
* @param length The length to encode.
*/
protected final void putLength(final int length) {
if (length < 0) {
throw new IllegalArgumentException() ;
}
else if (length < 128) {
bytes[--start] = (byte)length ;
}
else if (length < 256) {
bytes[--start] = (byte)length ;
bytes[--start] = (byte)0x81 ;
}
else if (length < 65536) {
bytes[--start] = (byte)(length) ;
bytes[--start] = (byte)(length >> 8) ;
bytes[--start] = (byte)0x82 ;
}
else if (length < 16777126) {
bytes[--start] = (byte)(length) ;
bytes[--start] = (byte)(length >> 8) ;
bytes[--start] = (byte)(length >> 16) ;
bytes[--start] = (byte)0x83 ;
}
else {
bytes[--start] = (byte)(length) ;
bytes[--start] = (byte)(length >> 8) ;
bytes[--start] = (byte)(length >> 16) ;
bytes[--start] = (byte)(length >> 24) ;
bytes[--start] = (byte)0x84 ;
}
}
/**
* Put an integer value and move the current position backward.
*
* @param v The integer to encode.
*/
protected final void putIntegerValue(int v) {
final int end = start ;
int mask = 0x7f800000 ;
int byteNeeded = 4 ;
if (v < 0) {
while (((mask & v) == mask) && (byteNeeded > 1)) {
mask = mask >> 8 ;
byteNeeded-- ;
}
}
else {
while (((mask & v) == 0) && (byteNeeded > 1)) {
mask = mask >> 8 ;
byteNeeded-- ;
}
}
for (int i = 0 ; i < byteNeeded ; i++) {
bytes[--start] = (byte)v ;
v = v >> 8 ;
}
putLength(end - start) ;
}
/**
* Put an integer value expressed as a long.
*
* @param v The integer to encode.
*/
protected final void putIntegerValue(long v) {
final int end = start ;
long mask = 0x7f80000000000000L ;
int byteNeeded = 8 ;
if (v < 0) {
while (((mask & v) == mask) && (byteNeeded > 1)) {
mask = mask >> 8 ;
byteNeeded-- ;
}
}
else {
while (((mask & v) == 0) && (byteNeeded > 1)) {
mask = mask >> 8 ;
byteNeeded-- ;
}
}
for (int i = 0 ; i < byteNeeded ; i++) {
bytes[--start] = (byte)v ;
v = v >> 8 ;
}
putLength(end - start) ;
}
/**
* Put a byte string and move the current position backward.
*
* @param s The byte string to encode.
*/
protected final void putStringValue(byte[] s) {
final int datalen = s.length;
java.lang.System.arraycopy(s,0,bytes,start-datalen,datalen);
start -= datalen;
// for (int i = s.length - 1 ; i >= 0 ; i--) {
// bytes[--start] = s[i] ;
// }
putLength(datalen) ;
}
/**
* Put an oid and move the current position backward.
*
* @param s The oid to encode.
*/
protected final void putOidValue(final long[] s) {
final int end = start ;
final int slength = s.length;
// bugId 4641746: 0, 1, and 2 are legal values.
if ((slength < 2) || (s[0] > 2) || (s[1] >= 40)) {
throw new IllegalArgumentException() ;
}
for (int i = slength - 1 ; i >= 2 ; i--) {
long c = s[i] ;
if (c < 0) {
throw new IllegalArgumentException() ;
}
else if (c < 128) {
bytes[--start] = (byte)c ;
}
else {
bytes[--start] = (byte)(c & 127) ;
c = c >> 7 ;
while (c != 0) {
bytes[--start] = (byte)(c | 128) ;
c = c >> 7 ;
}
}
}
bytes[--start] = (byte)(s[0] * 40 + s[1]) ;
putLength(end - start) ;
}
//
// This is the byte array containing the encoding.
//
protected final byte bytes[];
//
// This is the index of the first byte of the encoding.
// It is initialized to <CODE>bytes.length</CODE> and decrease each time
// an value is put in the encoder.
//
protected int start = -1 ;
//
// This is the stack where end of sequences are kept.
// A value is computed and pushed in it each time the <CODE>openSequence</CODE> method
// is invoked.
// A value is pulled and checked each time the <CODE>closeSequence</CODE> method is called.
//
protected final int stackBuf[] = new int[200] ;
protected int stackTop = 0 ;
}
|
