Package net.i2p.data.i2np

Class FastI2NPMessageImpl

java.lang.Object

net.i2p.data.i2np.I2NPMessageImpl

net.i2p.data.i2np.FastI2NPMessageImpl

All Implemented Interfaces:

I2NPMessage

Direct Known Subclasses:

DatabaseLookupMessage, DatabaseSearchReplyMessage, DatabaseStoreMessage, DataMessage, DeliveryStatusMessage, GarlicMessage, TunnelDataMessage, TunnelGatewayMessage, UnknownI2NPMessage

public abstract class FastI2NPMessageImpl
extends I2NPMessageImpl

Ignore, but save, the SHA-256 checksum in the full 16-byte header when read in. Use the same checksum when writing out. This is a savings for NTCP in, and for NTCP-in to NTCP-out for TunnelDataMessages. It's also a savings for messages embedded in other messages. Note that SSU does not use the SHA-256 checksum. Subclasses must take care to set _hasChecksum to false to invalidate it if the message payload changes between reading and writing. It isn't clear where, if anywhere, we actually need to send a checksum. For point-to-point messages over NTCP where we know the router version of the peer, we could add a method to skip checksum generation. For end-to-end I2NP messages embedded in a Garlic, TGM, etc... we would need a flag day.

Since:

0.8.12

Nested Class Summary

Nested classes/interfaces inherited from class net.i2p.data.i2np.I2NPMessageImpl

I2NPMessageImpl.Builder

Field Summary

Fields

Modifier and Type	Field	Description
protected byte	_checksum
protected boolean	_hasChecksum

Fields inherited from class net.i2p.data.i2np.I2NPMessageImpl

_context, _expiration, _log, CHECKSUM_LENGTH, DEFAULT_EXPIRATION_MS, HEADER_LENGTH

Fields inherited from interface net.i2p.data.i2np.I2NPMessage

MAX_ID_VALUE, MAX_SIZE

Constructor Summary

Constructors

Constructor	Description
FastI2NPMessageImpl(I2PAppContext context)

Method Summary

Modifier and Type	Method	Description
int	readBytes(byte[] data, int type, int offset, int maxLen)	Ignore, but save, the checksum, to be used later if necessary.
int	toByteArray(byte[] buffer)	If available, use the previously-computed or previously-read checksum for speed
protected int	toByteArrayWithSavedChecksum(byte[] buffer)	Use a previously-computed checksum for speed

Methods inherited from class net.i2p.data.i2np.I2NPMessageImpl

calculateWrittenLength, createMessage, fromRawByteArray, fromRawByteArrayNTCP2, getMessageExpiration, getMessageSize, getRawMessageSize, getUniqueId, readBytes, readBytes, readMessage, registerBuilder, setMessageExpiration, setUniqueId, toByteArray, toByteArray, toRawByteArray, toRawByteArrayNTCP2, writeBytes, writeMessageBody

Methods inherited from class java.lang.Object

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

Methods inherited from interface net.i2p.data.i2np.I2NPMessage

getType, readMessage

Field Detail

_checksum

protected byte _checksum

_hasChecksum

protected boolean _hasChecksum

Constructor Detail

FastI2NPMessageImpl

public FastI2NPMessageImpl(I2PAppContext context)

Method Detail

readBytes

public int readBytes(byte[] data,
                     int type,
                     int offset,
                     int maxLen)
              throws I2NPMessageException

Ignore, but save, the checksum, to be used later if necessary.

Specified by:

readBytes in interface I2NPMessage

Overrides:

readBytes in class I2NPMessageImpl

Parameters:

maxLen - read no more than this many bytes from data starting at offset, even if it is longer This includes the type byte only if type < 0

data - the data, may or may not include the type

type - the message type or -1 if we should read it here

offset - where to start starting at type if type is < 0 (16 byte header) starting at ID if type is >= 0 (15 byte header)

Returns:

total length of the message

Throws:

IllegalStateException - if called twice, to protect saved checksum

I2NPMessageException - if there is no valid message

toByteArray

public int toByteArray(byte[] buffer)

If available, use the previously-computed or previously-read checksum for speed

Specified by:

toByteArray in interface I2NPMessage

Overrides:

toByteArray in class I2NPMessageImpl

Returns:

the length written

toByteArrayWithSavedChecksum

protected int toByteArrayWithSavedChecksum(byte[] buffer)

Use a previously-computed checksum for speed