com.objsys.asn1j.runtime

Class Asn1NasDecodeBuffer

java.lang.Object

com.objsys.asn1j.runtime.Asn1MessageBufferBase

com.objsys.asn1j.runtime.Asn1MessageBuffer

com.objsys.asn1j.runtime.Asn1DecodeBuffer

com.objsys.asn1j.runtime.Asn1DecodeBitBuffer

com.objsys.asn1j.runtime.Asn1NasDecodeBuffer

All Implemented Interfaces:

Asn1BitMessageBuffer

public class Asn1NasDecodeBuffer
extends Asn1DecodeBitBuffer

This class handles non-ASN.1 encodings related to 3GPP specifications. NAS stands for Non-Access Stratum, though not everything this class is used for is necessarily part of NAS; we use the term NAS as more of an umbrella term for messages that are not defined using ASN.1.

Field Summary

Fields

Modifier and Type	Field and Description
static int	DOWNLINK
int	mDirection 3GPP Release Version.
int	mVersion 3GPP Release Version.
static int	UPLINK

Fields inherited from class com.objsys.asn1j.runtime.Asn1DecodeBitBuffer

mTraceHandler

Fields inherited from class com.objsys.asn1j.runtime.Asn1DecodeBuffer

mByteCount

Fields inherited from class com.objsys.asn1j.runtime.Asn1MessageBufferBase

context, mTypeCode

Constructor Summary

Constructors

Constructor and Description
Asn1NasDecodeBuffer(byte[] msgdata) This constructor creates a NAS decode buffer object that references an encoded message.
Asn1NasDecodeBuffer(java.io.InputStream istream) This constructor creates a NAS decode buffer object that references an encoded message.

Method Summary

Modifier and Type	Method and Description
boolean	containerHasMoreBits() Return true if there are more bits to be read in the current length-constrained container, which is possibly the outer PDU.
int	decodeAltDetmnt(int detmntBits, int lhmask) Decode an alternative determinant value in the given number of bits, translating L/H bits according to the pattern 0x2B and based on the buffer's bit offset.
java.lang.String	decodeAPN() Decode an APN string, following TS 24.008 and TS 23.003, and returning it in dot-notation (a.b.c) format.
void	decodeL3NonImperative(boolean callCtrl) This function decodes the non-imperative part of an L3 message having an empty non-imperative part.
void	decodeMCCMNC(Asn1IA5String mcc, Asn1IA5String mnc) Decode an MCC-MNC pair.
java.lang.String	decodeMobileIdentityType1(int len, boolean odd, byte digit1) This function is used to decode common data present in different alternatives within the MobileIdentify CHOICE type.
int	decodeVarAltDetmnt(Asn1NasAltDecodeTabEntry[] table) Decode a variable length alternative determinant according to the given table.
long	getContainerRemBits() Return the number of bits remaining to be read in the current container.
boolean	getPatternBit(byte pattern) This function picks out the bit from the given pattern that corresponds to the last bit read from this buffer.
boolean	isInsideContainer() Return true if a container length is on the container stack.
void	popAllContainers() Pop all containers from the container stack.
void	popContainer() Notify the runtime layer of the end of decoding of a length-constrained container of the given length.
void	pushContainerBits(long bits) Notify the runtime layer of the start of decoding of a length-constrained container of a given length.
void	pushContainerBytes(long bytes) Notify the runtime layer of the start of decoding of a length-constrained container of a given length.
void	skipToContainerEnd() Skip all bits, up to and including the last bit of the container from the top of the container stack.

Methods inherited from class com.objsys.asn1j.runtime.Asn1DecodeBitBuffer

binDump, binDump, byteAlign, decodeBit, decodeBitsToInt, decodeBitsToLong, decodeBitsToOctetArray, decodeBitsToOctetArray, getAvailableBits, getBitOffset, getBitOffsetInByte, getMsgBitCnt, getTraceHandler, hasMoreBits, mark, moveBitCursor, readByte, reset, setInputStream, skipBits

Methods inherited from class com.objsys.asn1j.runtime.Asn1DecodeBuffer

addCaptureBuffer, capture, decodeIntValue, decodeOIDContents, decodeOIDContentsBig, decodeRelOIDContents, decodeRelOIDContentsBig, getByteCount, getInputStream, getLazyOpenTypeDecode, hexDump, init, read, read, read, read2Bytes, read4Bytes, removeCaptureBuffer, setLazyOpenTypeDecode, skip, skipOIDContents, skipRelOIDContents

Methods inherited from class com.objsys.asn1j.runtime.Asn1MessageBuffer

addNamedEventHandler, getEventHandlerListCount, hasEventHandlers, invokeCharacters, invokeEndElement, invokeStartElement, setEventHandlerList

Methods inherited from class com.objsys.asn1j.runtime.Asn1MessageBufferBase

getContext, hexDump, hexDump, setKey, setTypeCode

Methods inherited from class java.lang.Object

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

Methods inherited from interface com.objsys.asn1j.runtime.Asn1BitMessageBuffer

getInputStream

Field Detail

mVersion

public int mVersion

3GPP Release Version. Setting this to 0 signals decoders to decode data for all 3GPP release versions. Setting this to a different value signals decoders to skip extensions from later versions (but not all decoders will pay attention to this).

DOWNLINK

public static final int DOWNLINK

See Also:

Constant Field Values

UPLINK

public static final int UPLINK

See Also:

Constant Field Values

mDirection

public int mDirection

3GPP Release Version. Setting this to 0 signals decoders to decode data for all 3GPP release versions. Setting this to a different value signals decoders to skip extensions from later versions (but not all decoders will pay attention to this).

Constructor Detail

Asn1NasDecodeBuffer

public Asn1NasDecodeBuffer(byte[] msgdata)

This constructor creates a NAS decode buffer object that references an encoded message.

Parameters:

msgdata - Byte array containing an encoded message.

Asn1NasDecodeBuffer

public Asn1NasDecodeBuffer(java.io.InputStream istream)

This constructor creates a NAS decode buffer object that references an encoded message. In this case, the message is passed in using an InputStream object.

Parameters:

istream - Input stream containing an encoded message.

Method Detail

containerHasMoreBits

public final boolean containerHasMoreBits()

Return true if there are more bits to be read in the current length-constrained container, which is possibly the outer PDU. See also pushContainer(Bits|Bytes)/popContainer

decodeAltDetmnt

public final int decodeAltDetmnt(int detmntBits,
                                 int lhmask)
                          throws java.io.IOException

Decode an alternative determinant value in the given number of bits, translating L/H bits according to the pattern 0x2B and based on the buffer's bit offset. The lhmask specifies which bits are L/H bits and which are simply 0/1 bits.

Parameters:

detmntBits - The number of bits to decode.

lhmask - A mask which indicates whether each bit in detmnt is a 0/1 bit or an L/H bit. L/H bits are represented in detmnt using 0/1, respectively. This is left-aligned so that the highest bit in the mask applies to the first bit to be decoded.

Returns:

The decoded determinant value.

Throws:

java.io.IOException

decodeAPN

public java.lang.String decodeAPN()
                           throws java.io.IOException

Decode an APN string, following TS 24.008 and TS 23.003, and returning it in dot-notation (a.b.c) format.

Returns:

The APN string.

Throws:

java.io.IOException

decodeMCCMNC

public void decodeMCCMNC(Asn1IA5String mcc,
                         Asn1IA5String mnc)
                  throws java.io.IOException

Decode an MCC-MNC pair.

Parameters:

mcc - Receives the MCC

mnc - Receives the MNC

Throws:

java.io.IOException

decodeVarAltDetmnt

public int decodeVarAltDetmnt(Asn1NasAltDecodeTabEntry[] table)
                       throws java.io.IOException

Decode a variable length alternative determinant according to the given table.

Parameters:

table - Controls decoding. See Asn1NasAltDecodeTabEntry.

Returns:

The decoded alternative.

Throws:

java.io.IOException

decodeL3NonImperative

public void decodeL3NonImperative(boolean callCtrl)
                           throws Asn1UnknownIEI,
                                  java.io.IOException

This function decodes the non-imperative part of an L3 message having an empty non-imperative part.

Parameters:

callCtrl - Boolean indicating this is a call control message.

Throws:

Asn1UnknownIEI - if an unknown comprehension required IE is found.

java.io.IOException

decodeMobileIdentityType1

public final java.lang.String decodeMobileIdentityType1(int len,
                                                        boolean odd,
                                                        byte digit1)
                                                 throws java.io.IOException

This function is used to decode common data present in different alternatives within the MobileIdentify CHOICE type. These include the IMSI, IMEI, and IMEISV alternatives.

Parameters:

len - Length in bytes of the data to be decoded. This includes 1 byte for the header.

odd - Odd/even indicator boolean decoded from header.

digit1 - First BCD character decoded from header.

Returns:

decoded value

Throws:

java.io.IOException

getPatternBit

public final boolean getPatternBit(byte pattern)

This function picks out the bit from the given pattern that corresponds to the last bit read from this buffer. For example, if the last read bit was the most significant bit of the byte, then this will return the value of the most significant bit in the given pattern. This can be used to get the value of a CSN.1 "L" bit by using pattern 0x2B or an H bit using pattern 0xD4.

Returns:

true for 1 bit, false for 0 bit, as described above

getContainerRemBits

public final long getContainerRemBits()

Return the number of bits remaining to be read in the current container. This can only be called when isInsideContainer() returns true.

Returns:

isInsideContainer

public final boolean isInsideContainer()

Return true if a container length is on the container stack. When this returns true, getContainerBits() returns the number of bits remaining in the container.

Returns:

pushContainerBytes

public final void pushContainerBytes(long bytes)

Notify the runtime layer of the start of decoding of a length-constrained container of a given length. This method should be called when the next bit to be decoded is the first bit of the length-constrained content. This pushes an entry onto the container stack.

Parameters:

bytes - Number of bytes of the length-constrained container.

pushContainerBits

public final void pushContainerBits(long bits)

Notify the runtime layer of the start of decoding of a length-constrained container of a given length. This method should be called when the next bit to be decoded is the first bit of the length-constrained content. This pushes an entry onto the container stack.

Parameters:

bits - Number of bits in the length-constrained container.

popContainer

public final void popContainer()

Notify the runtime layer of the end of decoding of a length-constrained container of the given length. This method should be called when the final bit to be decoded has been decoded. This pops an entry off of the container stack.

popAllContainers

public final void popAllContainers()

Pop all containers from the container stack. This is useful for clearing the stack when an error has occurred and the decode buffer is being reused.

skipToContainerEnd

public final void skipToContainerEnd()
                              throws java.io.IOException,
                                     Asn1EndOfBufferException

Skip all bits, up to and including the last bit of the container from the top of the container stack. The container stack must not be empty when this is invoked. This does not pop the container off the container stack.

Throws:

java.io.IOException

Asn1EndOfBufferException