TunnelDataMessage

net.i2p.data.i2np.TunnelDataMessage

All Implemented Interfaces:: I2NPMessage

public class TunnelDataMessageextends FastI2NPMessageImpl

Defines the message sent between routers as part of the tunnel delivery

The tunnel ID is changed in-place by TunnelParticipant.send(), so we can't reuse the checksum on output, but we still subclass FastI2NPMessageImpl so we don't verify the checksum on input... because this is a high-usage class.

Nested Class Summary
Nested classes/interfaces inherited from class I2NPMessageImpl
I2NPMessageImpl.Builder
Modifier and Type
Class
Description
static interface
I2NPMessageImpl.Builder
Interface for extending the types of messages handled - unused.
Field Summary
Modifier and Type
Field
Description
private static final ByteCache
_cache
Pooled buffers for message payloads.
private byte[]
_data
The message's payload bytes.
private ByteArray
_dataBuf
The payload as a buffer, for reuse.
private boolean
_hadCache
For use-after-free checks.
private long
_tunnelId
The tunnel this message is routed on.
private TunnelId
_tunnelIdObj
The tunnel id in object form.
static final int
DATA_SIZE
Size of the data payload in bytes.
private static final int
EXPIRATION_PERIOD
If we can't deliver a tunnel message in 10s, forget it.
static final int
MESSAGE_TYPE
Message type ID for this I2NP message.
private static final boolean
PIPELINED_CACHE
When true, this tunnelDataMessage is used as part of a tunnel processing pipeline.
Fields inherited from class FastI2NPMessageImpl
_checksum, _hasChecksum
Modifier and Type
Field
Description
protected byte
_checksum
One-byte checksum.
protected boolean
_hasChecksum
Whether the message includes a checksum.
Fields inherited from class I2NPMessageImpl
_context, _expiration, _log, CHECKSUM_LENGTH, DEFAULT_EXPIRATION_MS, HEADER_LENGTH
Modifier and Type
Field
Description
protected final I2PAppContext
_context
Application context this message belongs to.
protected long
_expiration
Expiration time in milliseconds since the epoch, as an I2P Date.
protected final Log
_log
Log for the message class, taken from the context's log manager.
static final int
CHECKSUM_LENGTH
Number of checksum bytes the message header carries.
static final long
DEFAULT_EXPIRATION_MS
Default lifetime of an unsent message, one minute in milliseconds.
static final int
HEADER_LENGTH
I2NP message header size in bytes.
Fields inherited from interface I2NPMessage
MAX_ID_VALUE, MAX_SIZE
Modifier and Type
Field
Description
static final long
MAX_ID_VALUE
4 bytes unsigned.
static final int
MAX_SIZE
Nominal limit, actual max is much less.
Constructor Summary
Constructors
Constructor
Description
TunnelDataMessage(I2PAppContext context)
Constructor with 10-second message expiration from context clock.
Method Summary
Public Methods
Modifier and Type
Method
Description
protected int
calculateWrittenLength()
Calculate the message body's length (not including the header and footer).
boolean
equals(Object object)
Two TunnelDataMessages are equal if they have the same tunnel ID and data.
byte[]
getData()
The payload this message carries, for a message already read or written.
long
getTunnelId()
Numeric form of the tunnel ID, for callers that cannot use a TunnelId.
TunnelId
getTunnelIdObj()
The TunnelId form of the tunnel ID, built once and then cached.
int
getType()
Return the type.
int
hashCode()
Hash based on tunnel ID and data payload.
void
readMessage(byte[] data, int offset, int dataSize, int type)
Read and parse the message from raw data into fields.
void
setData(byte[] data)
Tunnel payload; may only be set once.
void
setTunnelId(long id)
(correctly) Invalidates stored checksum.
void
setTunnelId(TunnelId id)
(correctly) Invalidates stored checksum.
byte[]
toByteArray()
Serialized message bytes with header and footer.
String
toString()
Label with unique ID for logging.
protected int
writeMessageBody(byte[] out, int curIndex)
Write the message body to the output array, starting at the given index.
Methods inherited from class FastI2NPMessageImpl
readBytes, toByteArray, toByteArrayWithSavedChecksum
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 I2NPMessageImpl
createMessage, fromRawByteArray, fromRawByteArrayNTCP2, getMessageExpiration, getMessageSize, getRawMessageSize, getUniqueId, getUniqueId, readBytes, readMessage, setMessageExpiration, setUniqueId, toByteArray, toRawByteArray, toRawByteArrayNTCP2
Modifier and Type
Method
Description
static I2NPMessage
createMessage(I2PAppContext context, int type)
Yes, this is fairly ugly, but its the only place it ever happens.
static I2NPMessage
fromRawByteArray(I2PAppContext ctx, byte[] buffer, int offset, int len, I2NPMessageHandler handler)
Read the message with a short 5-byte header.
static I2NPMessage
fromRawByteArrayNTCP2(I2PAppContext ctx, byte[] buffer, int offset, int len, I2NPMessageHandler handler)
Read the message with a short 9-byte header.
long
getMessageExpiration()
Date after which the message should be dropped (and the associated uniqueId forgotten).
int
getMessageSize()
Serialized message size, including the 16-byte header.
int
getRawMessageSize()
The raw header consists of a one-byte type and a 4-byte expiration in seconds only.
long
getUniqueId()
Unique id for this message, lazily initialized when negative.
long
getUniqueId(long msgIDBloomXor)
Replay resistant message Id.
int
readBytes(byte[] data, int type, int offset)
Read the header, then read the rest into buffer, then call readMessage in the implemented message type.
void
readMessage(byte[] data, int offset, int dataSize, int type, I2NPMessageHandler handler)
Read the message fields from the byte array, ignoring the handler.
void
setMessageExpiration(long exp)
The expiration is set to one minute from now in the constructor but it can be overridden here.
void
setUniqueId(long id)
The ID is set to a random value when written but it can be overridden here.
int
toByteArray(byte[] buffer, int off)
Write the message to the buffer, returning the new offset (NOT the length).
int
toRawByteArray(byte[] buffer)
Write the message with a short 5-byte header.
int
toRawByteArrayNTCP2(byte[] buffer, int off)
Write the message to the buffer, returning the new offset (NOT the length).
Methods inherited from class Object
clone, getClass, notify, notifyAll, wait, wait, wait

Field Details
- _tunnelId
  private long _tunnelId
  The tunnel this message is routed on.
- _tunnelIdObj
  private TunnelId _tunnelIdObj
  The tunnel id in object form.
- _data
  private byte[] _data
  The message's payload bytes.
- _dataBuf
  private ByteArray _dataBuf
  The payload as a buffer, for reuse.
- MESSAGE_TYPE
  public static final int MESSAGE_TYPE
  Message type ID for this I2NP message.
  See Also:
  Constant Field Values
- DATA_SIZE
  public static final int DATA_SIZE
  Size of the data payload in bytes.
  See Also:
  Constant Field Values
- EXPIRATION_PERIOD
  private static final int EXPIRATION_PERIOD
  If we can't deliver a tunnel message in 10s, forget it.
  See Also:
  Constant Field Values
- _cache
  private static final ByteCache _cache
  Pooled buffers for message payloads.
- PIPELINED_CACHE
  private static final boolean PIPELINED_CACHE
  When true, this tunnelDataMessage is used as part of a tunnel processing pipeline. The byte array is acquired during the TunnelDataMessage's creation (per readMessage), held onto through several transitions (updating and moving that array between different TunnelDataMessage instances or the fragment handler's cache, etc.), until it is finally released back into the cache when written to the next peer (or explicitly by the fragment handler's completion). Setting this to false just increases memory churn.
  This is tricky to get right and avoid data corruption.
  See Also:
  Constant Field Values
- _hadCache
  private boolean _hadCache
  For use-after-free checks. Always false if PIPELINED_CACHE is false.
Constructor Details
- TunnelDataMessage
  public TunnelDataMessage(I2PAppContext context)
  Constructor with 10-second message expiration from context clock.
  Parameters:
  context - the context whose clock supplies the expiration stamp
Method Details
- getTunnelId
  public long getTunnelId()
  Numeric form of the tunnel ID, for callers that cannot use a TunnelId.
  Returns:
  the tunnel this data message is addressed to
- setTunnelId
  public void setTunnelId(long id)
  (correctly) Invalidates stored checksum.
  Parameters:
  id - the tunnel to address; assigning it invalidates the cached checksum
- getTunnelIdObj
  public TunnelId getTunnelIdObj()
  The TunnelId form of the tunnel ID, built once and then cached.
  Returns:
  the cached TunnelId object for this message's tunnel
- setTunnelId
  public void setTunnelId(TunnelId id)
  (correctly) Invalidates stored checksum.
  Parameters:
  id - the tunnel to address; assigning it invalidates the cached checksum
- getData
  public byte[] getData()
  The payload this message carries, for a message already read or written.
  Returns:
  the tunnel payload bytes
- setData
  public void setData(byte[] data)
  Tunnel payload; may only be set once.
  Parameters:
  data - the payload to carry; must be non-empty and may only be assigned once
  Throws:
  IllegalStateException - if data previously set, to protect saved checksum
- readMessage
  public void readMessage(byte[] data, int offset, int dataSize, int type) throws I2NPMessageException
  Read and parse the message from raw data into fields.
  Parameters:
  data - data to read from
  offset - where to start in the data array
  dataSize - how long into the data to read
  type - I2NP message type
  Throws:
  I2NPMessageException - if the stream doesn't contain a valid message that this class can read.
- calculateWrittenLength
  protected int calculateWrittenLength()
  Calculate the message body's length (not including the header and footer).
  Specified by:
  calculateWrittenLength in class I2NPMessageImpl
  Returns:
  the number of bytes the body will occupy once serialized
- writeMessageBody
  protected int writeMessageBody(byte[] out, int curIndex) throws I2NPMessageException
  Write the message body to the output array, starting at the given index.
  Specified by:
  writeMessageBody in class I2NPMessageImpl
  Parameters:
  out - the buffer to serialize the body into
  curIndex - the offset into out at which to begin writing; leave room for the signature where the header format calls for one
  Returns:
  the index into the array after the last byte written (NOT the length)
  Throws:
  I2NPMessageException - if the body cannot be serialized into out, because it is too small or a field is unserializable
- getType
  public int getType()
  Return the type.
  Returns:
  the message type number, as defined in the I2NP spec
- hashCode
  public int hashCode()
  Hash based on tunnel ID and data payload.
  Overrides:
  hashCode in class Object
  Returns:
  whether h code is present
- equals
  public boolean equals(Object object)
  Two TunnelDataMessages are equal if they have the same tunnel ID and data.
  Overrides:
  equals in class Object
- toByteArray
  public byte[] toByteArray()
  Serialized message bytes with header and footer.
  Specified by:
  toByteArray in interface I2NPMessage
  Overrides:
  toByteArray in class I2NPMessageImpl
  Returns:
  a new array holding the whole message, full 16 byte header included
- toString
  public String toString()
  Label with unique ID for logging.
  Overrides:
  toString in class Object

Nested Class Summary

Nested classes/interfaces inherited from class I2NPMessageImpl

Field Summary

Fields inherited from class FastI2NPMessageImpl

Fields inherited from class I2NPMessageImpl

Fields inherited from interface I2NPMessage

Constructor Summary

Method Summary

Methods inherited from class FastI2NPMessageImpl

Methods inherited from class I2NPMessageImpl

Methods inherited from class Object

Field Details

_tunnelId

_tunnelIdObj

_data

_dataBuf

MESSAGE_TYPE

DATA_SIZE

EXPIRATION_PERIOD

_cache

PIPELINED_CACHE

_hadCache

Constructor Details

Method Details

getTunnelId

setTunnelId

getTunnelIdObj

setTunnelId

getData

setData

readMessage

calculateWrittenLength

writeMessageBody

getType

hashCode

equals

toByteArray

toString