org.snmp4j.asn1

Class BER

java.lang.Object

org.snmp4j.asn1.BER

public class BER
extends Object

The BER class provides utility methods for the BER encoding and decoding.

Version:

2.5.8

Author:

Frank Fock, Jochen Katz

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	BER.MutableByte The MutableByte class serves for exchanging type information from the various decode* methods.

Field Summary

Fields

Modifier and Type	Field and Description
static byte	ASN_APPLICATION
static byte	ASN_BIT_STR
static byte	ASN_BIT8
static byte	ASN_BOOLEAN
static byte	ASN_CONSTRUCTOR
static byte	ASN_CONTEXT
static byte	ASN_EXTENSION_ID
static byte	ASN_INTEGER
static byte	ASN_LONG_LEN
static byte	ASN_NULL
static byte	ASN_OBJECT_ID
static byte	ASN_OCTET_STR
static byte	ASN_PRIMITIVE
static byte	ASN_PRIVATE
static byte	ASN_SEQUENCE
static byte	ASN_SET
static byte	ASN_UNIVERSAL
static byte	BITSTRING
static byte	COUNTER
static byte	COUNTER32
static byte	COUNTER64
static int	ENDOFMIBVIEW
static byte	GAUGE
static byte	GAUGE32
static byte	INTEGER
static byte	INTEGER32
static byte	IPADDRESS
static int	MAX_OID_LENGTH
static int	NOSUCHINSTANCE
static int	NOSUCHOBJECT
static byte	NULL
static byte	OCTETSTRING
static byte	OID
static byte	OPAQUE
static byte	SEQUENCE
static byte	TIMETICKS

Constructor Summary

Constructors

Constructor and Description
BER()

Method Summary

Modifier and Type	Method and Description
static void	checkSequenceLength(int expectedLength, BERSerializable sequence)
static void	checkSequenceLength(int expectedLength, int actualLength, BERSerializable sequence)
static BigInteger	decodeBigInteger(BERInputStream is, BER.MutableByte type)
static int	decodeHeader(BERInputStream is, BER.MutableByte type) Decodes an ASN.1 header for an object with the ID and length specified.
static int	decodeHeader(BERInputStream is, BER.MutableByte type, boolean checkLength) Decodes an ASN.1 header for an object with the ID and length specified.
static int	decodeInteger(BERInputStream is, BER.MutableByte type)
static int	decodeLength(BERInputStream is) Decodes a ASN.1 length.
static int	decodeLength(BERInputStream is, boolean checkLength) Decodes a ASN.1 length.
static void	decodeNull(BERInputStream is, BER.MutableByte type)
static int[]	decodeOID(BERInputStream is, BER.MutableByte type)
static byte[]	decodeString(BERInputStream is, BER.MutableByte type)
static long	decodeUnsignedInt64(BERInputStream is, BER.MutableByte type)
static long	decodeUnsignedInteger(BERInputStream is, BER.MutableByte type)
static void	encodeBigInteger(OutputStream os, byte type, BigInteger value) Encode a signed integer.
static void	encodeHeader(OutputStream os, int type, int length) Encodes an ASN.1 header for an object with the ID and length specified.
static void	encodeHeader(OutputStream os, int type, int length, int numBytesLength) Encodes an ASN.1 header for an object with the ID and length specified with a fixed length of the encoded length as supplied.
static void	encodeInteger(OutputStream os, byte type, int value) Encode a signed integer.
static void	encodeLength(OutputStream os, int length) Encodes the length of an ASN.1 object.
static void	encodeLength(OutputStream os, int length, int numLengthBytes) Encodes the length of an ASN.1 object.
static void	encodeOID(OutputStream os, byte type, int[] oid) Encode an ASN.1 oid filled with the supplied oid value.
static void	encodeSequence(OutputStream os, byte type, int length) Encode an ASN.1 header for a sequence with the ID and length specified.
static void	encodeString(OutputStream os, byte type, byte[] string) Encode an ASN.1 octet string filled with the supplied input string.
static void	encodeUnsignedInt64(OutputStream os, byte type, long value)
static void	encodeUnsignedInteger(OutputStream os, byte type, long value) Encode an unsigned integer.
static int	getBERLengthOfLength(int length) Compute the space needed to encode the length.
static int	getBigIntegerBERLength(BigInteger value) Get the BER encoded length of a BigInteger value.
static int	getOIDLength(int[] value) Gets the payload length in bytes of the BER encoded OID value.
static boolean	isCheckFirstSubID012()
static boolean	isCheckSequenceLength() Gets the SEQUENCE length checking mode.
boolean	isCheckValueLength()
static void	setCheckFirstSubID012(boolean checkFirstSubID012)
static void	setCheckSequenceLength(boolean checkSequenceLen) Sets the application wide SEQUENCE length checking mode.
void	setCheckValueLength(boolean checkValueLength)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ASN_BOOLEAN

public static final byte ASN_BOOLEAN

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Constant Field Values

ASN_INTEGER

public static final byte ASN_INTEGER

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Constant Field Values

ASN_BIT_STR

public static final byte ASN_BIT_STR

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Constant Field Values

ASN_OCTET_STR

public static final byte ASN_OCTET_STR

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ASN_NULL

public static final byte ASN_NULL

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ASN_OBJECT_ID

public static final byte ASN_OBJECT_ID

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ASN_SEQUENCE

public static final byte ASN_SEQUENCE

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ASN_SET

public static final byte ASN_SET

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Constant Field Values

ASN_UNIVERSAL

public static final byte ASN_UNIVERSAL

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ASN_APPLICATION

public static final byte ASN_APPLICATION

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ASN_CONTEXT

public static final byte ASN_CONTEXT

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ASN_PRIVATE

public static final byte ASN_PRIVATE

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ASN_PRIMITIVE

public static final byte ASN_PRIMITIVE

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ASN_CONSTRUCTOR

public static final byte ASN_CONSTRUCTOR

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ASN_LONG_LEN

public static final byte ASN_LONG_LEN

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Constant Field Values

ASN_EXTENSION_ID

public static final byte ASN_EXTENSION_ID

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Constant Field Values

ASN_BIT8

public static final byte ASN_BIT8

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INTEGER

public static final byte INTEGER

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INTEGER32

public static final byte INTEGER32

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BITSTRING

public static final byte BITSTRING

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Constant Field Values

OCTETSTRING

public static final byte OCTETSTRING

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NULL

public static final byte NULL

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OID

public static final byte OID

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SEQUENCE

public static final byte SEQUENCE

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IPADDRESS

public static final byte IPADDRESS

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COUNTER

public static final byte COUNTER

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COUNTER32

public static final byte COUNTER32

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GAUGE

public static final byte GAUGE

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GAUGE32

public static final byte GAUGE32

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Constant Field Values

TIMETICKS

public static final byte TIMETICKS

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Constant Field Values

OPAQUE

public static final byte OPAQUE

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COUNTER64

public static final byte COUNTER64

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Constant Field Values

NOSUCHOBJECT

public static final int NOSUCHOBJECT

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NOSUCHINSTANCE

public static final int NOSUCHINSTANCE

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ENDOFMIBVIEW

public static final int ENDOFMIBVIEW

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MAX_OID_LENGTH

public static final int MAX_OID_LENGTH

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Constructor Detail

BER

public BER()

Method Detail

encodeHeader

public static void encodeHeader(OutputStream os,
                                int type,
                                int length)
                         throws IOException

Encodes an ASN.1 header for an object with the ID and length specified.

Parameters:

os - an OutputStream to which the header is encoded.

type - the type of the ASN.1 object. Must be < 30, i.e. no extension octets.

length - the length of the object. The maximum length is 0xFFFFFFFF;

Throws:

IOException - if the output stream fails to store the encoded header.

encodeHeader

public static void encodeHeader(OutputStream os,
                                int type,
                                int length,
                                int numBytesLength)
                         throws IOException

Encodes an ASN.1 header for an object with the ID and length specified with a fixed length of the encoded length as supplied.

Parameters:

os - an OutputStream to which the header is encoded.

type - the type of the ASN.1 object. Must be < 30, i.e. no extension octets.

length - the length of the object. The maximum length is 0xFFFFFFFF;

numBytesLength - the number of bytes used to encode the length of the length.

Throws:

IOException - if the output stream fails to store the encoded header.

getBERLengthOfLength

public static int getBERLengthOfLength(int length)

Compute the space needed to encode the length.

Parameters:

length - Length to encode

Returns:

the count of bytes needed to encode the value length

encodeLength

public static void encodeLength(OutputStream os,
                                int length)
                         throws IOException

Encodes the length of an ASN.1 object.

Parameters:

os - an OutputStream to which the length is encoded.

length - the length of the object. The maximum length is 0xFFFFFFFF;

Throws:

IOException - if the output stream fails to store the encoded length.

encodeLength

public static void encodeLength(OutputStream os,
                                int length,
                                int numLengthBytes)
                         throws IOException

Encodes the length of an ASN.1 object.

Parameters:

os - an OutputStream to which the length is encoded.

length - the length of the object. The maximum length is 0xFFFFFFFF;

numLengthBytes - the number of bytes to be used to encode the length using the long form.

Throws:

IOException - if the output stream fails to store the encoded length.

encodeInteger

public static void encodeInteger(OutputStream os,
                                 byte type,
                                 int value)
                          throws IOException

Encode a signed integer.

Parameters:

os - an OutputStream to which the length is encoded.

type - the tag type for the integer (typically 0x02)

value - the integer value to encode.

Throws:

IOException - if the output stream fails to store the encoded integer.

encodeBigInteger

public static void encodeBigInteger(OutputStream os,
                                    byte type,
                                    BigInteger value)
                             throws IOException

Encode a signed integer.

Parameters:

os - an OutputStream to which the length is encoded.

type - the tag type for the integer (typically 0x02)

value - the integer value to encode.

Throws:

IOException - if the output stream fails to store the encoded integer.

getBigIntegerBERLength

public static int getBigIntegerBERLength(BigInteger value)

Get the BER encoded length of a BigInteger value.

Parameters:

value - a BigInteger value with a length that is less 2^31.

Returns:

the length of the BER encoding of the supplied BigInteger as INTEGER value.

encodeUnsignedInteger

public static void encodeUnsignedInteger(OutputStream os,
                                         byte type,
                                         long value)
                                  throws IOException

Encode an unsigned integer. ASN.1 integer ::= 0x02 asnlength byte {byte}*

Parameters:

os - an OutputStream to which the length is encoded.

type - the tag type for the integer (typically 0x02)

value - the integer value to encode.

Throws:

IOException - if the output stream fails to store the encoded value.

encodeString

public static void encodeString(OutputStream os,
                                byte type,
                                byte[] string)
                         throws IOException

Encode an ASN.1 octet string filled with the supplied input string.

Parameters:

os - an OutputStream to which the length is encoded.

type - the tag type for the integer (typically 0x02)

string - the byte array containing the octet string value.

Throws:

IOException - if the output stream fails to store the encoded value.

encodeSequence

public static void encodeSequence(OutputStream os,
                                  byte type,
                                  int length)
                           throws IOException

Encode an ASN.1 header for a sequence with the ID and length specified. This only works on data types < 30, i.e. no extension octets. The maximum length is 0xFFFF;

Parameters:

os - an OutputStream to which the length is encoded.

type - the tag type for the integer (typically 0x02)

length - the length of the sequence to encode.

Throws:

IOException - if the output stream fails to store the encoded value.

getOIDLength

public static int getOIDLength(int[] value)

Gets the payload length in bytes of the BER encoded OID value.

Parameters:

value - an array of unsigned integer values representing an object identifier.

Returns:

the BER encoded length of the OID without header and length.

encodeOID

public static void encodeOID(OutputStream os,
                             byte type,
                             int[] oid)
                      throws IOException

Encode an ASN.1 oid filled with the supplied oid value.

Parameters:

os - an OutputStream to which the length is encoded.

type - the tag type for the integer (typically 0x06)

oid - the int array containing the OID value.

Throws:

IOException - if the output stream fails to store the encoded value.

encodeUnsignedInt64

public static void encodeUnsignedInt64(OutputStream os,
                                       byte type,
                                       long value)
                                throws IOException

Throws:

IOException

decodeLength

public static int decodeLength(BERInputStream is)
                        throws IOException

Decodes a ASN.1 length.

Parameters:

is - an InputStream

Returns:

the decoded length.

Throws:

IOException - if the input stream contains an invalid BER encoding or an IO exception occurred while reading from the stream.

decodeLength

public static int decodeLength(BERInputStream is,
                               boolean checkLength)
                        throws IOException

Decodes a ASN.1 length.

Parameters:

is - an InputStream

checkLength - if false length check is always suppressed.

Returns:

the decoded length.

Throws:

IOException - if the input stream contains an invalid BER encoding or an IO exception occurred while reading from the stream.

decodeHeader

public static int decodeHeader(BERInputStream is,
                               BER.MutableByte type,
                               boolean checkLength)
                        throws IOException

Decodes an ASN.1 header for an object with the ID and length specified. On entry, datalength is input as the number of valid bytes following "data". On exit, it is returned as the number of valid bytes in this object following the id and length. This only works on data types < 30, i.e. no extension octets. The maximum length is 0xFFFF;

Parameters:

is - the BERInputStream to decode.

type - returns the type of the object at the current position in the input stream.

checkLength - if false length check is always suppressed.

Returns:

the decoded length of the object.

Throws:

IOException - if the input stream contains an invalid BER encoding or an IO exception occurred while reading from the stream.

decodeHeader

public static int decodeHeader(BERInputStream is,
                               BER.MutableByte type)
                        throws IOException

Decodes an ASN.1 header for an object with the ID and length specified. On entry, datalength is input as the number of valid bytes following "data". On exit, it is returned as the number of valid bytes in this object following the id and length. This only works on data types < 30, i.e. no extension octets. The maximum length is 0xFFFF;

Parameters:

is - the BERInputStream to decode.

type - returns the type of the object at the current position in the input stream.

Returns:

the decoded length of the object.

Throws:

IOException - if the input stream contains an invalid BER encoding or an IO exception occurred while reading from the stream.

decodeInteger

public static int decodeInteger(BERInputStream is,
                                BER.MutableByte type)
                         throws IOException

Throws:

IOException

decodeBigInteger

public static BigInteger decodeBigInteger(BERInputStream is,
                                          BER.MutableByte type)
                                   throws IOException

Throws:

IOException

decodeUnsignedInteger

public static long decodeUnsignedInteger(BERInputStream is,
                                         BER.MutableByte type)
                                  throws IOException

Throws:

IOException

decodeString

public static byte[] decodeString(BERInputStream is,
                                  BER.MutableByte type)
                           throws IOException

Throws:

IOException

decodeOID

public static int[] decodeOID(BERInputStream is,
                              BER.MutableByte type)
                       throws IOException

Throws:

IOException

decodeNull

public static void decodeNull(BERInputStream is,
                              BER.MutableByte type)
                       throws IOException

Throws:

IOException

decodeUnsignedInt64

public static long decodeUnsignedInt64(BERInputStream is,
                                       BER.MutableByte type)
                                throws IOException

Throws:

IOException

isCheckSequenceLength

public static boolean isCheckSequenceLength()

Gets the SEQUENCE length checking mode.

Returns:

true if the length of a parsed SEQUENCE should be checked against the real length of the objects parsed.

setCheckSequenceLength

public static void setCheckSequenceLength(boolean checkSequenceLen)

Sets the application wide SEQUENCE length checking mode.

Parameters:

checkSequenceLen - specifies whether he length of a parsed SEQUENCE should be checked against the real length of the objects parsed.

checkSequenceLength

public static void checkSequenceLength(int expectedLength,
                                       BERSerializable sequence)
                                throws IOException

Throws:

IOException

checkSequenceLength

public static void checkSequenceLength(int expectedLength,
                                       int actualLength,
                                       BERSerializable sequence)
                                throws IOException

Throws:

IOException

isCheckValueLength

public boolean isCheckValueLength()

setCheckValueLength

public void setCheckValueLength(boolean checkValueLength)

isCheckFirstSubID012

public static boolean isCheckFirstSubID012()

setCheckFirstSubID012

public static void setCheckFirstSubID012(boolean checkFirstSubID012)