com.mindbright.ssh2

Class SSH2TransportPDU

java.lang.Object

com.mindbright.ssh2.SSH2DataBuffer

com.mindbright.ssh2.SSH2TransportPDU

Direct Known Subclasses:

SSH2TransportPDUPool, SSH2TransportPDUPool.PoolPDU

public class SSH2TransportPDU
extends SSH2DataBuffer

Handles one packet data unit. These are the actual packets which are sent over en encrypted tunnel. Encryption and compression are applied to these.

There is a difference bwteeen incoming and outgoing PDUs. The latter have extra space allocated in them to help speed up the encryption process.

This class makes an effort to avoid copying data wherever possible.

Field Summary

Fields

Modifier and Type	Field and Description
static SSH2TransportPDU	factoryInstance
static int	PACKET_DEFAULT_SIZE
static int	PACKET_MAX_SIZE
static int	PACKET_MIN_SIZE
protected int	padSize
static int	pktDefaultSize
protected int	pktSize
protected int	pktType
protected int	totSizeCompressed
protected int	totSizeUncompressed

Fields inherited from class com.mindbright.ssh2.SSH2DataBuffer

BOOLEAN_FALSE, BOOLEAN_TRUE, data, rPos, wPos

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	SSH2TransportPDU()
protected	SSH2TransportPDU(int pktType, int bufSize) Constructor which creates a prefabricated packet.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	checkMac(javax.crypto.Mac mac, int macSize)
static SSH2TransportPDU	createIncomingPacket() Have the factory create a PDU for an incoming packet.
static SSH2TransportPDU	createIncomingPacket(int bufSize) Have the factory create a PDU for an incoming packet.
protected SSH2TransportPDU	createInPDU(int bufSize) Create a new PDU to use for incoming packets.
static SSH2TransportPDU	createOutgoingPacket(int pktType) Have the factory create a PDU for an outgoing packet.
static SSH2TransportPDU	createOutgoingPacket(int pktType, int bufSize) Have the factory create a PDU for an outgoing packet.
protected SSH2TransportPDU	createOutPDU(int pktType, int bufSize) Create a new PDU for an outgoing packet.
protected SSH2TransportPDU	createPDU(int pktType, int bufSize) Create a new PDU for a packet.
static SSH2Transport.TransceiverContext	createTransceiverContext(java.lang.String cipherName, int cipherDiscard, java.lang.String macName, int macLength, java.lang.String compName, NonBlockingInput in) Static function which creates a transceiver context with the mentioned algorithms.
SSH2Transport.TransceiverContext	createTransceiverContextImpl(java.lang.String cipherName, int cipherDiscard, java.lang.String macName, int macLength, java.lang.String compName, NonBlockingInput in) An implementation which actually creates a transceiver context.
void	fillData(byte[] buf, int bufpos, int n)
int	getCompressedSize()
int	getNeededBytes()
int	getPayloadLength() Get the length of the payload.
int	getPayloadOffset() Get the offset in the data buffer where the payload starts.
int	getType()
int	getUncompressedSize()
void	initReceive(int seqNum, SSH2Transport.TransceiverContext context) Prepare this PDU for receiving data.
SSH2TransportPDU	makeCopy() Create a copy of this PDU.
boolean	processData() Read and decrypt data from the given stream.
void	release() Release this PDU.
static void	setFactoryInstance(SSH2TransportPDU factory) Register a factor which handles the creation and destruction of incoming and outgoing packets.
void	setType(int pktType)
java.lang.String	toString() Creates a string representation of this PDU.
void	writeByte(int b)
void	writeRaw(byte[] raw, int off, int len)
void	writeString(byte[] str, int off, int len)
void	writeTo(NonBlockingOutput out, int seqNum, SSH2Transport.TransceiverContext context, SecureRandomAndPad rand) Encrypts and writes an outgoing packet to the stream.

Methods inherited from class com.mindbright.ssh2.SSH2DataBuffer

getData, getMaxReadSize, getMaxSize, getMaxWriteSize, getRPos, getWPos, readBigInt, readBigIntBits, readBoolean, readByte, readInt, readJavaString, readLong, readRaw, readRaw, readRestRaw, readString, readString, readUInt, reset, resize, setData, setRPos, setWPos, writeBigInt, writeBigIntBits, writeBoolean, writeInt, writeInt, writeLong, writeRaw, writeString, writeString, writeUTF8String

Methods inherited from class java.lang.Object

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

Field Detail

PACKET_DEFAULT_SIZE

public static final int PACKET_DEFAULT_SIZE

See Also:

Constant Field Values

PACKET_MIN_SIZE

public static final int PACKET_MIN_SIZE

See Also:

Constant Field Values

PACKET_MAX_SIZE

public static final int PACKET_MAX_SIZE

See Also:

Constant Field Values

pktDefaultSize

public static int pktDefaultSize

factoryInstance

public static SSH2TransportPDU factoryInstance

pktSize

protected int pktSize

padSize

protected int padSize

pktType

protected int pktType

totSizeCompressed

protected int totSizeCompressed

totSizeUncompressed

protected int totSizeUncompressed

Constructor Detail

SSH2TransportPDU

protected SSH2TransportPDU()

SSH2TransportPDU

protected SSH2TransportPDU(int pktType,
                int bufSize)

Constructor which creates a prefabricated packet.

Parameters:

pktType - Type of packet to create.

bufSize - How many bytes it should have room for.

Method Detail

createInPDU

protected SSH2TransportPDU createInPDU(int bufSize)

Create a new PDU to use for incoming packets.

Parameters:

bufSize - How many bytes it should have room for.

createOutPDU

protected SSH2TransportPDU createOutPDU(int pktType,
                            int bufSize)

Create a new PDU for an outgoing packet.

Parameters:

pktType - Type of packet to create.

bufSize - How many bytes it should have room for.

createPDU

protected SSH2TransportPDU createPDU(int pktType,
                         int bufSize)

Create a new PDU for a packet.

Parameters:

pktType - Type of packet to create.

bufSize - How many bytes it should have room for.

setFactoryInstance

public static final void setFactoryInstance(SSH2TransportPDU factory)

Register a factor which handles the creation and destruction of incoming and outgoing packets.

createIncomingPacket

public static final SSH2TransportPDU createIncomingPacket(int bufSize)

Have the factory create a PDU for an incoming packet.

Parameters:

bufSize - How many bytes it should have room for.

createIncomingPacket

public static final SSH2TransportPDU createIncomingPacket()

Have the factory create a PDU for an incoming packet.

createOutgoingPacket

public static final SSH2TransportPDU createOutgoingPacket(int pktType,
                                    int bufSize)

Have the factory create a PDU for an outgoing packet.

Parameters:

pktType - Type of packet to create.

bufSize - How many bytes it should have room for.

createOutgoingPacket

public static final SSH2TransportPDU createOutgoingPacket(int pktType)

Have the factory create a PDU for an outgoing packet.

Parameters:

pktType - Type of packet to create.

createTransceiverContext

public static final SSH2Transport.TransceiverContext createTransceiverContext(java.lang.String cipherName,
                                                        int cipherDiscard,
                                                        java.lang.String macName,
                                                        int macLength,
                                                        java.lang.String compName,
                                                        NonBlockingInput in)
                                                                       throws java.lang.Exception

Static function which creates a transceiver context with the mentioned algorithms.

Parameters:

cipherName - Name of cipher algorithm to use.

cipherDiscard - How many bytes to discard after key init.

macName - Name of message authentication cipher to use.

macLength - How many bytes of the mac digest to use

compName - Name of compression algorithm to use.

Throws:

java.lang.Exception

release

public void release()

Release this PDU. This means that the PDU can be freed or reused for another packet.

makeCopy

public SSH2TransportPDU makeCopy()

Create a copy of this PDU.

getType

public int getType()

setType

public void setType(int pktType)

getPayloadLength

public int getPayloadLength()

Get the length of the payload. The payload is the actual data sent. Note that the payload may still be compressed.

getPayloadOffset

public int getPayloadOffset()

Get the offset in the data buffer where the payload starts.

getCompressedSize

public int getCompressedSize()

getUncompressedSize

public int getUncompressedSize()

initReceive

public void initReceive(int seqNum,
               SSH2Transport.TransceiverContext context)

Prepare this PDU for receiving data.

Parameters:

seqNum - Sequence number of packet.

context - Transceiver context.

getNeededBytes

public int getNeededBytes()

fillData

public void fillData(byte[] buf,
            int bufpos,
            int n)

processData

public boolean processData()
                    throws SSH2Exception,
                           javax.crypto.ShortBufferException,
                           java.security.GeneralSecurityException

Read and decrypt data from the given stream. This function handles decryption, mac checking and uncompression. When we get there we know that the data buffer holds at least as many bytes as we previously prepared it for in prepareForRead

Returns:

True if more data is needed to create the entire packet, otherwise False

Throws:

SSH2Exception

javax.crypto.ShortBufferException

java.security.GeneralSecurityException

checkMac

protected void checkMac(javax.crypto.Mac mac,
            int macSize)
                 throws SSH2MacCheckException,
                        java.security.GeneralSecurityException

Throws:

SSH2MacCheckException

java.security.GeneralSecurityException

writeByte

public final void writeByte(int b)

Overrides:

writeByte in class SSH2DataBuffer

writeString

public final void writeString(byte[] str,
               int off,
               int len)

Overrides:

writeString in class SSH2DataBuffer

writeRaw

public final void writeRaw(byte[] raw,
            int off,
            int len)

Overrides:

writeRaw in class SSH2DataBuffer

writeTo

public void writeTo(NonBlockingOutput out,
           int seqNum,
           SSH2Transport.TransceiverContext context,
           SecureRandomAndPad rand)
             throws java.io.IOException,
                    java.security.GeneralSecurityException,
                    SSH2CompressionException

Encrypts and writes an outgoing packet to the stream. This function handles compression, mac calculation and encryption.

Parameters:

out - Stream to write resulting data to.

seqNum - Sequence number of packet.

context - Transceiver context to use.

rand - An object from which random numbers and padding data is read.

Throws:

java.io.IOException

java.security.GeneralSecurityException

SSH2CompressionException

toString

public java.lang.String toString()

Creates a string representation of this PDU.

Overrides:

toString in class java.lang.Object

createTransceiverContextImpl

public SSH2Transport.TransceiverContext createTransceiverContextImpl(java.lang.String cipherName,
                                                            int cipherDiscard,
                                                            java.lang.String macName,
                                                            int macLength,
                                                            java.lang.String compName,
                                                            NonBlockingInput in)
                                                              throws java.lang.Exception

An implementation which actually creates a transceiver context.

Parameters:

cipherName - Name of cipher algorithm to use.

cipherDiscard - How many bytes to discard after key init.

macName - Name of message authentication cipher to use.

macLength - How many bytes of the mac digest to use

compName - Name of compression algorithm to use.

Throws:

java.lang.Exception