Class DDMReader

java.lang.Object
org.apache.derby.impl.drda.DDMReader
class DDMReader extends Object
The DDMReader is used to read DRDA protocol. DRDA Protocol is divided into three layers corresponding to the DDM three-tier architecture. For each layer, their is a DSS (Data Stream Structure) defined. Layer A Communications management services Layer B Agent services Layer C Data management services

At layer A are request, reply and data correlation, structure chaining, continuation or termination of chains when errors are detected, interleaving and multi-leaving request, reply, and data DSSs for multitasking environments. For TCP/IP, the format of the DDM envelope is 2 bytes Length of the data 1 byte 'D0' - indicates DDM data 1 byte DDM format byte(DSSFMT) - type of DSS(RQSDSS,RPYDSS), whether it is chained, information about the next chained DSS 2 bytes request correlation identifier

The correlation identifier ties together a request, the request data and the reply. In a chained DSS, each request has a correlation identifier which is higher than the previous request (all correlation identifiers must be greater than 0).

At layer B are object mapping, object validation and command routing. Layer B objects with data 5 bytes less than 32K bytes consist of 2 bytes Length 2 bytes Type of the object (code point) Object data Object data is either SCALAR or COLLECTION data. Scalar data consists of a string of bytes formatted as the class description of the object required. Collections consist of a set of objects in which the entries in the collection are nested within the length/ code point of the collection.

Layer B objects with data >=32763 bytes long format is 2 bytes Length - length of class, length, and extended total length fields (high order bit set, indicating >=32763) 2 bytes Type of the object (code point) n bytes Extended total length - length of the object (n = Length - 4) Object data

At layer C are services each class of DDM object provides. |-------------------------------------------| Layer C | Specific | Specific | Specific | | Commands | Replies | Scalars and | | and their | and their | Collections | |-------------------------------------------|----------------| Layer B | Commands | Reply | Scalars and | Communications | | | Messages | Collections | | |-----------|---------------|---------------|----------------| Layer A | RQSDSS | RPYDSS | OBJDSS | CMNDSS | | | | | Mapped Data | |-----------|---------------|---------------|----------------| | DDM Data Stream Structures | |------------------------------------------------------------| DSS's may be chained so that more than one can be transmitted at a time to improve performance. For more details, see DRDA Volume 3 (Distributed Data Management(DDM) Architecture (DDS definition)

  • Field Details

    • DEFAULT_BUFFER_SIZE

      private static final int DEFAULT_BUFFER_SIZE
      See Also:

    • MAX_MARKS_NESTING

      private static final int MAX_MARKS_NESTING
      See Also:

    • NO_CODEPOINT

      private static final int NO_CODEPOINT
      See Also:

    • EMPTY_STACK

      private static final int EMPTY_STACK
      See Also:

    • ADJUST_LENGTHS

      private static final boolean ADJUST_LENGTHS
      See Also:

    • NO_ADJUST_LENGTHS

      private static final boolean NO_ADJUST_LENGTHS
      See Also:

    • MAX_EXTDTA_SIZE

      private static final long MAX_EXTDTA_SIZE
      See Also:

    • tenRadixMagnitude

      private static final int[][] tenRadixMagnitude

    • agent

      private DRDAConnThread agent

    • utf8CcsidManager

      private Utf8CcsidManager utf8CcsidManager

    • ebcdicCcsidManager

      private EbcdicCcsidManager ebcdicCcsidManager

    • ccsidManager

      private CcsidManager ccsidManager

    • buffer

      private byte[] buffer

    • pos

      private int pos

    • count

      private int count

    • topDdmCollectionStack

      private int topDdmCollectionStack

    • ddmCollectionLenStack

      private long[] ddmCollectionLenStack

    • ddmScalarLen

      private long ddmScalarLen

    • dssLength

      private int dssLength

    • dssIsContinued

      private boolean dssIsContinued

    • terminateChainOnErr

      private boolean terminateChainOnErr

    • dssIsChainedWithSameID

      private boolean dssIsChainedWithSameID

    • dssIsChainedWithDiffID

      private boolean dssIsChainedWithDiffID

    • dssCorrelationID

      private int dssCorrelationID

    • prevCorrelationID

      private int prevCorrelationID

    • svrcod

      private int svrcod

    • dssTrace

      private DssTrace dssTrace

    • inputStream

      private InputStream inputStream

    • doingLayerBStreaming

      private boolean doingLayerBStreaming

    • totalByteCount

      volatile long totalByteCount

  • Constructor Details

    • DDMReader

      DDMReader(DRDAConnThread agent, DssTrace dssTrace)

    • DDMReader

      DDMReader(InputStream inputStream)
      This constructor is used for testing the protocol It is used by ProtocolTestAdapter to read the protocol returned by the server

  • Method Details

    • initialize

      protected void initialize(DRDAConnThread agent, DssTrace dssTrace)
      Initialize values for this session, the reader is reused so we need to set null and 0 values

    • setUtf8Ccsid

      protected void setUtf8Ccsid()

    • setEbcdicCcsid

      protected void setEbcdicCcsid()

    • terminateChainOnErr

      protected boolean terminateChainOnErr()

    • isChainedWithSameID

      protected boolean isChainedWithSameID()
      Next DSS has same correlator as current DSS
      Returns:
      true if next DSS has the same correlator as current DSS

    • isChainedWithDiffID

      protected boolean isChainedWithDiffID()
      Next DSS has different correlator than current DSS
      Returns:
      true if next DSS has a different correlator than current DSS

    • getDdmLength

      protected long getDdmLength()
      Length of current DDM object
      Returns:
      length of DDM object

    • moreDdmData

      protected boolean moreDdmData()
      Is there more in this DDM object
      Returns:
      true if DDM length is > 0

    • moreDssData

      protected boolean moreDssData()
      Is there more in this DDS object
      Returns:
      true if DDS length is > 0

    • moreData

      protected boolean moreData()
      Is there more data in the buffer
      Returns:
      true if there is more data in the buffer

    • isCmd

      protected boolean isCmd() throws DRDAProtocolException, UnsupportedEncodingException
      Check for the command protocol
      Returns:
      true if this is a command; false otherwise
      Throws:
      DRDAProtocolException - if a protocol error is detected
      UnsupportedEncodingException

    • readDssHeader

      protected int readDssHeader() throws DRDAProtocolException
      Read DSS header DSS Header format is 2 bytes - length 1 byte - 'D0' - indicates DDM data 1 byte - DSS format |---|---------|----------| | 0 | flags | type | |---|---------|----------| | 0 | 1 2 3 | 4 5 6 7 | |---|---------|----------| bit 0 - '0' bit 1 - '0' - unchained, '1' - chained bit 2 - '0' - do not continue on error, '1' - continue on error bit 3 - '0' - next DSS has different correlator, '1' - next DSS has same correlator type - 1 - Request DSS - 2 - Reply DSS - 3 - Object DSS - 4 - Communications DSS - 5 - Request DSS where no reply is expected 2 bytes - request correlation id
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readReplyDss

      protected void readReplyDss() throws DRDAProtocolException
      Read Reply DSS This is used in testing the protocol. We shouldn't see a reply DSS when we are servicing DRDA commands
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readLengthAndCodePoint

      protected int readLengthAndCodePoint(boolean isLayerBStreamingPossible) throws DRDAProtocolException
      Read the DDM Length and CodePoint
      Parameters:
      isLayerBStreamingPossible - true only when layer B streaming is possible
      Returns:
      - returns codepoint
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readCodePoint

      protected int readCodePoint()
      Read the CodePoint
      Returns:
      - returns codepoint

    • markCollection

      protected void markCollection()
      Push DDM Length on to collection stack

    • getCodePoint

      protected int getCodePoint() throws DRDAProtocolException
      Get the next CodePoint from a collection
      Returns:
      NO_CODEPOINT if collection stack is empty or remaining length is 0; otherwise, read length and code point
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • getCodePoint

      protected int getCodePoint(int codePointCheck) throws DRDAProtocolException
      Get the next CodePoint from a collection and check that it matches the specified CodePoint
      Parameters:
      codePointCheck - - codePoint to check against
      Returns:
      codePoint
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readByte

      protected byte readByte() throws DRDAProtocolException
      Read byte value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readUnsignedByte

      protected int readUnsignedByte() throws DRDAProtocolException
      Read byte value and mask out high order bytes before returning
      Returns:
      value
      Throws:
      DRDAProtocolException

    • readNetworkShort

      protected int readNetworkShort() throws DRDAProtocolException
      Read network short value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readSignedNetworkShort

      protected int readSignedNetworkShort() throws DRDAProtocolException
      Read signed network short value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readShort

      protected short readShort(int byteOrder) throws DRDAProtocolException
      Read platform short value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readNetworkInt

      protected int readNetworkInt() throws DRDAProtocolException
      Read network int value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readInt

      protected int readInt(int byteOrder) throws DRDAProtocolException
      Read platform int value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readNetworkLong

      protected long readNetworkLong() throws DRDAProtocolException
      Read network long value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readNetworkSixByteLong

      protected long readNetworkSixByteLong() throws DRDAProtocolException
      Read network six byte value and put it in a long v
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readLong

      protected long readLong(int byteOrder) throws DRDAProtocolException
      Read platform long value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readFloat

      protected float readFloat(int byteOrder) throws DRDAProtocolException
      Read platform float value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readDouble

      protected double readDouble(int byteOrder) throws DRDAProtocolException
      Read platform double value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readBigDecimal

      protected BigDecimal readBigDecimal(int precision, int scale) throws DRDAProtocolException
      Read a BigDecimal value
      Parameters:
      precision - of the BigDecimal
      scale - of the BigDecimal
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • getEXTDTAReaderInputStream

      EXTDTAReaderInputStream getEXTDTAReaderInputStream(boolean checkNullability) throws DRDAProtocolException
      Creates an InputStream which can stream EXTDTA objects. The InputStream uses this DDMReader to read data from network. The DDMReader should not be used before all data in the stream has been read.
      Parameters:
      checkNullability - used to check if the stream is null. If it is null, this method returns null
      Returns:
      EXTDTAReaderInputStream object which can be passed to prepared statement as a binary stream.
      Throws:
      DRDAProtocolException - standard DRDA protocol exception

    • readLOBInitStream

      ByteArrayInputStream readLOBInitStream() throws DRDAProtocolException
      This method is used by EXTDTAReaderInputStream to read the first chunk of data. This lengthless method must be called only when layer B streaming.
      Throws:
      DRDAProtocolException - standard DRDA protocol exception

    • readLOBInitStream

      ByteArrayInputStream readLOBInitStream(long desiredLength) throws DRDAProtocolException
      This method is used by EXTDTAReaderInputStream to read the first chunk of data.
      Parameters:
      desiredLength - the desired length of chunk. This parameter is ignored when layerB Streaming is doing.
      Throws:
      DRDAProtocolException - standard DRDA protocol exception

    • readLOBContinuationStream

      ByteArrayInputStream readLOBContinuationStream() throws IOException
      This method is used by EXTDTAReaderInputStream to read the next chunk of data. Calling this method finishes layer B streaming if continuation of DSS segment was finished. This lengthless method must be called only when layer B streaming.
      Throws:
      IOException - IOException

    • readLOBContinuationStream

      ByteArrayInputStream readLOBContinuationStream(long desiredLength) throws IOException
      This method is used by EXTDTAReaderInputStream to read the next chunk of data. Furthermore, when Layer B streaming is carried out, calling this method finishes layer B streaming if continuation of DSS segment was finished.
      Parameters:
      desiredLength - the desired length of chunk. This parameter is ignored when layerB Streaming is doing.
      Throws:
      IOException - IOException

    • readLOBChunk

      private ByteArrayInputStream readLOBChunk(boolean readHeader, long desiredLength) throws DRDAProtocolException
      This method is used by EXTDTAReaderInputStream to read the next chunk of data. Furthermore, when Layer B streaming is carried out, calling this method may finish layer B streaming.
      Parameters:
      readHeader - set to true if the dss continuation should be read
      desiredLength - the desired length of chunk. This parameter is ignored when layerB Streaming is doing.
      Throws:
      DRDAProtocolException - standard DRDA protocol exception

    • getExtData

      byte[] getExtData(long desiredLength, boolean checkNullability) throws DRDAProtocolException
      Throws:
      DRDAProtocolException

    • readDSSContinuationHeader

      private void readDSSContinuationHeader() throws DRDAProtocolException
      Throws:
      DRDAProtocolException

    • isEXTDTANull

      private boolean isEXTDTANull() throws DRDAProtocolException
      Throws:
      DRDAProtocolException

    • packedNybblesToInt

      private int packedNybblesToInt(byte[] buffer, int offset, int startNybble, int numberOfNybbles)
      Convert a range of packed nybbles (up to 9 digits without overflow) to an int. Note that for performance purpose, it does not do array-out-of-bound checking.
      Parameters:
      buffer - buffer to read from
      offset - offset in the buffer
      startNybble - start nybble
      numberOfNybbles - number of nybbles
      Returns:
      an int value

    • packedNybblesToLong

      private long packedNybblesToLong(byte[] buffer, int offset, int startNybble, int numberOfNybbles)
      Convert a range of packed nybbles (up to 18 digits without overflow) to a long. Note that for performance purpose, it does not do array-out-of-bound checking.
      Parameters:
      buffer - buffer to read from
      offset - offset in the buffer
      startNybble - start nybble
      numberOfNybbles - number of nybbles
      Returns:
      an long value

    • computeMagnitude

      private int[] computeMagnitude(int[] input)
      Compute the int array of magnitude from input value segments.
      Parameters:
      input - value segments
      Returns:
      array of int magnitudes

    • readEncryptedString

      protected String readEncryptedString(DecryptionManager decryptM, int securityMechanism, byte[] initVector, byte[] sourcePublicKey) throws DRDAProtocolException, SQLException
      Read encrypted string
      Parameters:
      decryptM - decryption manager
      securityMechanism - security mechanism
      initVector - initialization vector for cipher
      sourcePublicKey - public key (as in Deffie-Hellman algorithm) from source (encryptor)
      Returns:
      decrypted string
      Throws:
      DRDAProtocolException - if a protocol error is detected
      SQLException - wrapping any exception in decryption

    • readString

      protected String readString(int length) throws DRDAProtocolException
      Read string value Strings in DRDA protocol are encoded in EBCDIC by default so we need to convert to UCS2
      Parameters:
      length - - length of string to read
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readString

      protected void readString(DRDAString dst, int size, boolean unpad) throws DRDAProtocolException
      Read string value into a DRDAString object.
      Parameters:
      dst - destination for the read string
      size - size (in bytes) of string to read
      unpad - if true, remove padding (trailing spaces)
      Throws:
      DRDAProtocolException

    • readString

      protected String readString(int length, String encoding) throws DRDAProtocolException
      Read encoded string value
      Parameters:
      length - - length of string to read
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readStringData

      protected String readStringData(int length) throws DRDAProtocolException
      Read specified length of string value in DDM data with default encoding
      Parameters:
      length - - length of string to read
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readLDStringData

      protected String readLDStringData(String encoding) throws DRDAProtocolException
      Read length delimited string value in DDM data with default encoding
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readString

      protected String readString() throws DRDAProtocolException
      Read string value
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readBytes

      protected byte[] readBytes(int length) throws DRDAProtocolException
      Read byte string value
      Parameters:
      length - - length of string to read
      Returns:
      byte array
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • readBytes

      protected byte[] readBytes() throws DRDAProtocolException
      Read byte string value
      Returns:
      byte array
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • skipBytes

      protected void skipBytes(int length) throws DRDAProtocolException
      Skip byte string value
      Parameters:
      length - - length of string to skip
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • skipBytes

      protected void skipBytes() throws DRDAProtocolException
      Skip byte string value
      Throws:
      DRDAProtocolException

    • skipDss

      protected void skipDss() throws DRDAProtocolException
      Skip remaining DSS
      Throws:
      DRDAProtocolException

    • clearBuffer

      protected void clearBuffer() throws DRDAProtocolException
      Throws:
      DRDAProtocolException

    • convertBytes

      protected String convertBytes(byte[] buf)
      Convert EBCDIC byte array to unicode string
      Parameters:
      buf - - byte array
      Returns:
      string

    • adjustLengths

      private void adjustLengths(int length)
      Adjust remaining length
      Parameters:
      length - - adjustment length

    • readCmdString

      protected String readCmdString(int length) throws DRDAProtocolException, UnsupportedEncodingException
      Read string value
      Parameters:
      length - - length of string to read
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected
      UnsupportedEncodingException

    • readCmdString

      protected String readCmdString() throws DRDAProtocolException, UnsupportedEncodingException
      Read string value
      Returns:
      value
      Throws:
      DRDAProtocolException - if a protocol error is detected
      UnsupportedEncodingException

    • ensureALayerDataInBuffer

      private void ensureALayerDataInBuffer(int desiredDataSize) throws DRDAProtocolException
      Make sure a certain amount of Layer A data is in the buffer. The data will be in the buffer after this method is called.
      Parameters:
      desiredDataSize - - amount of data we need
      Throws:
      DRDAProtocolException

    • ensureBLayerDataInBuffer

      private void ensureBLayerDataInBuffer(int desiredDataSize, boolean adjustLen) throws DRDAProtocolException
      Make sure a certain amount of Layer B data is in the buffer. The data will be in the buffer after this method is called.
      Parameters:
      desiredDataSize - - amount of data we need
      adjustLen - - whether to adjust the remaining lengths
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • compressBLayerData

      private void compressBLayerData(int continueDssHeaderCount) throws DRDAProtocolException
      Compress B Layer data if extended total length is used by removing the continuation headers
      Parameters:
      continueDssHeaderCount - - amount of data we need
      Throws:
      DRDAProtocolException

    • shiftBuffer

      private void shiftBuffer(byte[] destinationBuffer)
      This is a helper method which shifts the buffered bytes from wherever they are in the current buffer to the beginning of different buffer (note these buffers could be the same). State information is updated as needed after the shift.
      Parameters:
      destinationBuffer - - buffer to shift data to

    • ensureSpaceInBufferForFill

      private void ensureSpaceInBufferForFill(int desiredSpace)
      This method makes sure there is enough room in the buffer for a certain number of bytes. This method will allocate a new buffer if needed and shift the bytes in the current buffer to make ensure space is available for a fill. Right now this method will shift bytes as needed to make sure there is as much room as possible in the buffer before trying to do the read. The idea is to try to have space to get as much data as possible if we need to do a read on the socket's stream.
      Parameters:
      desiredSpace - - amount of data we need

    • fill

      private void fill(int minimumBytesNeeded) throws DRDAProtocolException
      This method will attempt to read a minimum number of bytes from the underlying stream. This method will keep trying to read bytes until it has obtained at least the minimum number.
      Parameters:
      minimumBytesNeeded - - minimum required bytes
      Throws:
      DRDAProtocolException - if a protocol error is detected

    • trace

      private void trace(String msg)
      Print a internal trace message

    • getCurrChainState

      protected byte getCurrChainState()
      Return chaining bit for current DSS.

    • startLayerBStreaming

      private void startLayerBStreaming()

    • finishLayerBStreaming

      private void finishLayerBStreaming()

    • doingLayerBStreaming

      boolean doingLayerBStreaming()