/* * @(#)file BerEncoder.java * @(#)author Sun Microsystems, Inc. * @(#)version 4.17 * @(#)date 07/03/14 * * Copyright 2006 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. * */ package com.sun.jmx.snmp; /** * The BerEncoder class is used for encoding data using BER. * * A BerEncoder needs to be set up with a byte buffer. The encoded * data are stored in this byte buffer. * * NOTE : the buffer is filled from end to start. This means the caller * needs to encode its data in the reverse order. * * * This API is a Sun Microsystems internal API and is subject * to change without notice. * @version 4.17 11/17/05 * @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 trim method. * * After a call to the trim method, the encoder is reinitialized and putXXX * 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 NULL value. */ public void putNull() { putNull(NullTag) ; } /** * Put a NULL value with a specified tag. * * @param tag The tag to encode. */ public void putNull(int tag) { putLength(0) ; putTag(tag) ; } /** * Put an ANY value. In fact, this method does not encode anything. * It simply copies the specified bytes into the encoding. * * @param s The encoding of the ANY value. */ public void putAny(byte[] s) { putAny(s, s.length) ; } /** * Put an ANY value. Only the first byteCount are considered. * * @param s The encoding of the ANY 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 } } } /** * 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 bytes.length 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 openSequence method // is invoked. // A value is pulled and checked each time the closeSequence method is called. // protected final int stackBuf[] = new int[200] ; protected int stackTop = 0 ; }
