BerDecoder class is used for decoding
- * BER-encoded data.
- *
- * A BerDecoder needs to be set up with the byte string containing
- * the encoding. It maintains a current position in the byte string.
- *
- * Methods allows to fetch integer, string, OID, etc., from the current
- * position. After a fetch the current position is moved forward.
- *
- * A fetch throws a BerException if the encoding is not of the
- * expected type.
- *
- * This API is a Sun Microsystems internal API and is subject - * to change without notice.
- * - * @since 1.5 - */ - -public class BerDecoder { - - /** - * Constructs a new decoder and attaches it to the specified byte string. - * - * @param b The byte string containing the encoded data. - */ - - public BerDecoder(byte b[]) { - bytes = b ; - reset() ; - } - - public void reset() { - next = 0 ; - stackTop = 0 ; - } - - /** - * Fetch an integer. - * - * @return The decoded integer. - * - * @exception BerException Current position does not point to an integer. - */ - - public int fetchInteger() throws BerException { - return fetchInteger(IntegerTag) ; - } - - - /** - * Fetch an integer with the specified tag. - * - * @param tag The expected tag. - * - * @return The decoded integer. - * - * @exception BerException Current position does not point to an integer - * or the tag is not the expected one. - */ - - public int fetchInteger(int tag) throws BerException { - int result = 0 ; - final int backup = next ; - try { - if (fetchTag() != tag) { - throw new BerException() ; - } - result = fetchIntegerValue() ; - } - catch(BerException e) { - next = backup ; - throw e ; - } - - return result ; - } - - - - /** - * Fetch an integer and return a long value. - * - * @return The decoded integer. - * - * @exception BerException Current position does not point to an integer. - */ - - public long fetchIntegerAsLong() throws BerException { - return fetchIntegerAsLong(IntegerTag) ; - } - - - /** - * Fetch an integer with the specified tag and return a long value. - * - * @param tag The expected tag. - * - * @return The decoded integer. - * - * @exception BerException Current position does not point to an integer - * or the tag is not the expected one. - */ - - public long fetchIntegerAsLong(int tag) throws BerException { - long result = 0 ; - final int backup = next ; - try { - if (fetchTag() != tag) { - throw new BerException() ; - } - result = fetchIntegerValueAsLong() ; - } - catch(BerException e) { - next = backup ; - throw e ; - } - - return result ; - } - - - - /** - * Fetch an octet string. - * - * @return The decoded string. - * - * @exception BerException Current position does not point to an octet string. - */ - - public byte[] fetchOctetString() throws BerException { - return fetchOctetString(OctetStringTag) ; - } - - - /** - * Fetch an octet string with a specified tag. - * - * @param tag The expected tag. - * - * @return The decoded string. - * - * @exception BerException Current position does not point to an octet string - * or the tag is not the expected one. - */ - - public byte[] fetchOctetString(int tag) throws BerException { - byte[] result = null ; - final int backup = next ; - try { - if (fetchTag() != tag) { - throw new BerException() ; - } - result = fetchStringValue() ; - } - catch(BerException e) { - next = backup ; - throw e ; - } - - return result ; - } - - - /** - * Fetch an object identifier. - * - * @return The decoded object identifier as an array of long. - */ - - public long[] fetchOid() throws BerException { - return fetchOid(OidTag) ; - } - - - /** - * Fetch an object identifier with a specified tag. - * - * @param tag The expected tag. - * - * @return The decoded object identifier as an array of long. - * - * @exception BerException Current position does not point to an oid - * or the tag is not the expected one. - */ - - public long[] fetchOid(int tag) throws BerException { - long[] result = null ; - final int backup = next ; - try { - if (fetchTag() != tag) { - throw new BerException() ; - } - result = fetchOidValue() ; - } - catch(BerException e) { - next = backup ; - throw e ; - } - - return result ; - } - - - /** - * Fetch aNULL value.
- *
- * @exception BerException Current position does not point to NULL value.
- */
-
- public void fetchNull() throws BerException {
- fetchNull(NullTag) ;
- }
-
-
- /**
- * Fetch a NULL value with a specified tag.
- *
- * @param tag The expected tag.
- *
- * @exception BerException Current position does not point to
- * NULL value or the tag is not the expected one.
- */
-
- public void fetchNull(int tag) throws BerException {
- final int backup = next ;
- try {
- if (fetchTag() != tag) {
- throw new BerException() ;
- }
- final int length = fetchLength();
- if (length != 0) throw new BerException();
- }
- catch(BerException e) {
- next = backup ;
- throw e ;
- }
- }
-
-
-
- /**
- * Fetch an ANY value. In fact, this method does not decode anything
- * it simply returns the next TLV as an array of bytes.
- *
- * @return The TLV as a byte array.
- *
- * @exception BerException The next TLV is really badly encoded...
- */
-
- public byte[] fetchAny() throws BerException {
- byte[] result = null ;
- final int backup = next ;
- try {
- final int tag = fetchTag() ;
- final int contentLength = fetchLength() ;
- if (contentLength < 0) throw new BerException() ;
- final int tlvLength = next + contentLength - backup ;
- if (contentLength > (bytes.length - next))
- throw new IndexOutOfBoundsException("Decoded length exceeds buffer");
- final byte[] data = new byte[tlvLength] ;
- java.lang.System.arraycopy(bytes,backup,data,0,tlvLength);
- // for (int i = 0 ; i < tlvLength ; i++) {
- // data[i] = bytes[backup + i] ;
- // }
- next = next + contentLength ;
- result = data;
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
- // catch(Error e) {
- // debug("fetchAny: Error decoding BER: " + e);
- // throw e;
- // }
-
- return result ;
- }
-
-
- /**
- * Fetch an ANY value with a specific tag.
- *
- * @param tag The expected tag.
- *
- * @return The TLV as a byte array.
- *
- * @exception BerException The next TLV is really badly encoded...
- */
-
- public byte[] fetchAny(int tag) throws BerException {
- if (getTag() != tag) {
- throw new BerException() ;
- }
- return fetchAny() ;
- }
-
-
-
- /**
- * Fetch a sequence header.
- * The decoder computes the end position of the sequence and push it
- * on its stack.
- *
- * @exception BerException Current position does not point to a sequence header.
- */
-
- public void openSequence() throws BerException {
- openSequence(SequenceTag) ;
- }
-
-
- /**
- * Fetch a sequence header with a specific tag.
- *
- * @param tag The expected tag.
- *
- * @exception BerException Current position does not point to a sequence header
- * or the tag is not the expected one.
- */
-
- public void openSequence(int tag) throws BerException {
- final int backup = next ;
- try {
- if (fetchTag() != tag) {
- throw new BerException() ;
- }
- final int l = fetchLength() ;
- if (l < 0) throw new BerException();
- if (l > (bytes.length - next)) throw new BerException();
- stackBuf[stackTop++] = next + l ;
- }
- catch(BerException e) {
- next = backup ;
- throw e ;
- }
- }
-
-
- /**
- * Close a sequence.
- * The decode pull the stack and verifies that the current position
- * matches with the calculated end of the sequence. If not it throws
- * an exception.
- *
- * @exception BerException The sequence is not expected to finish here.
- */
-
- public void closeSequence() throws BerException {
- if (stackBuf[stackTop - 1] == next) {
- stackTop-- ;
- }
- else {
- throw new BerException() ;
- }
- }
-
-
- /**
- * Return true if the end of the current sequence is not reached.
- * When this method returns false, closeSequence can (and must) be
- * invoked.
- *
- * @return true if there is still some data in the sequence.
- */
-
- public boolean cannotCloseSequence() {
- return (next < stackBuf[stackTop - 1]) ;
- }
-
-
- /**
- * Get the tag of the data at the current position.
- * Current position is unchanged.
- *
- * @return The next tag.
- */
-
- public int getTag() throws BerException {
- int result = 0 ;
- final int backup = next ;
- try {
- result = fetchTag() ;
- }
- finally {
- next = backup ;
- }
-
- return result ;
- }
-
-
-
- public String toString() {
- final StringBuffer result = new StringBuffer(bytes.length * 2) ;
- for (int i = 0 ; i < bytes.length ; i++) {
- final int b = (bytes[i] > 0) ? bytes[i] : bytes[i] + 256 ;
- if (i == next) {
- result.append("(") ;
- }
- result.append(Character.forDigit(b / 16, 16)) ;
- result.append(Character.forDigit(b % 16, 16)) ;
- if (i == next) {
- result.append(")") ;
- }
- }
- if (bytes.length == next) {
- result.append("()") ;
- }
-
- return new String(result) ;
- }
-
-
- //
- // 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 ;
-
-
-
-
- ////////////////////////// PRIVATE ///////////////////////////////
-
-
-
- /**
- * Fetch a tag and move the current position forward.
- *
- * @return The tag
- */
-
- private final int fetchTag() throws BerException {
- int result = 0 ;
- final int backup = next ;
-
- try {
- final byte b0 = bytes[next++] ;
- result = (b0 >= 0) ? b0 : b0 + 256 ;
- if ((result & 31) == 31) {
- while ((bytes[next] & 128) != 0) {
- result = result << 7 ;
- result = result | (bytes[next++] & 127);
- }
- }
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
-
- return result ;
- }
-
-
- /**
- * Fetch a length and move the current position forward.
- *
- * @return The length
- */
-
- private final int fetchLength() throws BerException {
- int result = 0 ;
- final int backup = next ;
-
- try {
- final byte b0 = bytes[next++] ;
- if (b0 >= 0) {
- result = b0 ;
- }
- else {
- for (int c = 128 + b0 ; c > 0 ; c--) {
- final byte bX = bytes[next++] ;
- result = result << 8 ;
- result = result | ((bX >= 0) ? bX : bX+256) ;
- }
- }
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
-
- return result ;
- }
-
-
- /**
- * Fetch an integer value and move the current position forward.
- *
- * @return The integer
- */
-
- private int fetchIntegerValue() throws BerException {
- int result = 0 ;
- final int backup = next ;
-
- try {
- final int length = fetchLength() ;
- if (length <= 0) throw new BerException() ;
- if (length > (bytes.length - next)) throw
- new IndexOutOfBoundsException("Decoded length exceeds buffer");
- final int end = next + length ;
- result = bytes[next++] ;
- while (next < end) {
- final byte b = bytes[next++] ;
- if (b < 0) {
- result = (result << 8) | (256 + b) ;
- }
- else {
- result = (result << 8) | b ;
- }
- }
- }
- catch(BerException e) {
- next = backup ;
- throw e ;
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
- catch(ArithmeticException e) {
- next = backup ;
- throw new BerException() ;
- }
- return result ;
- }
-
-
- /**
- * Fetch an integer value and return a long value.
- * FIX ME: someday we could have only on fetchIntegerValue() which always
- * returns a long value.
- *
- * @return The integer
- */
-
- private final long fetchIntegerValueAsLong() throws BerException {
- long result = 0 ;
- final int backup = next ;
-
- try {
- final int length = fetchLength() ;
- if (length <= 0) throw new BerException() ;
- if (length > (bytes.length - next)) throw
- new IndexOutOfBoundsException("Decoded length exceeds buffer");
-
- final int end = next + length ;
- result = bytes[next++] ;
- while (next < end) {
- final byte b = bytes[next++] ;
- if (b < 0) {
- result = (result << 8) | (256 + b) ;
- }
- else {
- result = (result << 8) | b ;
- }
- }
- }
- catch(BerException e) {
- next = backup ;
- throw e ;
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
- catch(ArithmeticException e) {
- next = backup ;
- throw new BerException() ;
- }
- return result ;
- }
-
-
- /**
- * Fetch a byte string and move the current position forward.
- *
- * @return The byte string
- */
-
- private byte[] fetchStringValue() throws BerException {
- byte[] result = null ;
- final int backup = next ;
-
- try {
- final int length = fetchLength() ;
- if (length < 0) throw new BerException() ;
- if (length > (bytes.length - next))
- throw new IndexOutOfBoundsException("Decoded length exceeds buffer");
- final byte data[] = new byte[length] ;
- java.lang.System.arraycopy(bytes,next,data,0,length);
- next += length;
- // int i = 0 ;
- // while (i < length) {
- // result[i++] = bytes[next++] ;
- // }
- result = data;
- }
- catch(BerException e) {
- next = backup ;
- throw e ;
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
- catch(ArithmeticException e) {
- next = backup ;
- throw new BerException() ;
- }
- // catch(Error e) {
- // debug("fetchStringValue: Error decoding BER: " + e);
- // throw e;
- // }
-
- return result ;
- }
-
-
-
- /**
- * Fetch an oid and move the current position forward.
- *
- * @return The oid
- */
-
- private final long[] fetchOidValue() throws BerException {
- long[] result = null ;
- final int backup = next ;
-
- try {
- final int length = fetchLength() ;
- if (length <= 0) throw new BerException() ;
- if (length > (bytes.length - next))
- throw new IndexOutOfBoundsException("Decoded length exceeds buffer");
- // Count how many bytes have their 8th bit to 0
- // -> this gives the number of components in the oid
- int subidCount = 2 ;
- for (int i = 1 ; i < length ; i++) {
- if ((bytes[next + i] & 0x80) == 0) {
- subidCount++ ;
- }
- }
- final int datalen = subidCount;
- final long[] data = new long[datalen];
- final byte b0 = bytes[next++] ;
-
- // bugId 4641746
- // The 8th bit of the first byte should always be set to 0
- if (b0 < 0) throw new BerException();
-
- // bugId 4641746
- // The first sub Id cannot be greater than 2
- final long lb0 = b0 / 40 ;
- if (lb0 > 2) throw new BerException();
-
- final long lb1 = b0 % 40;
- data[0] = lb0 ;
- data[1] = lb1 ;
- int i = 2 ;
- while (i < datalen) {
- long subid = 0 ;
- byte b = bytes[next++] ;
- while ((b & 0x80) != 0) {
- subid = (subid << 7) | (b & 0x7f) ;
- // bugId 4654674
- if (subid < 0) throw new BerException();
- b = bytes[next++] ;
- }
- subid = (subid << 7) | b ;
- // bugId 4654674
- if (subid < 0) throw new BerException();
- data[i++] = subid ;
- }
- result = data;
- }
- catch(BerException e) {
- next = backup ;
- throw e ;
- }
- catch(IndexOutOfBoundsException e) {
- next = backup ;
- throw new BerException() ;
- }
- // catch(Error e) {
- // debug("fetchOidValue: Error decoding BER: " + e);
- // throw e;
- // }
-
- return result ;
- }
-
- // private static final void debug(String str) {
- // System.out.println(str);
- // }
-
- //
- // This is the byte array containing the encoding.
- //
- private final byte bytes[];
-
- //
- // This is the current location. It is the next byte
- // to be decoded. It's an index in bytes[].
- //
- private int next = 0 ;
-
- //
- // This is the stack where end of sequences are kept.
- // A value is computed and pushed in it each time openSequence()
- // is invoked.
- // A value is pulled and checked each time closeSequence() is called.
- //
- private final int stackBuf[] = new int[200] ;
- private int stackTop = 0 ;
-
-}