net.i2p.data

Class Payload

java.lang.Object

net.i2p.data.DataStructureImpl

net.i2p.data.Payload

All Implemented Interfaces:

Serializable, DataStructure

public class Payload
extends DataStructureImpl

Message payload container for I2P communications with encryption support.

Payload provides message content delivery in I2P:

• Message Content: Contains actual data being delivered
• Encryption Support: Standard encryption wrapping per I2P spec
• I2CP Protocol: Primarily used in client-router communication
• Legacy Feature: Previously supported end-to-end encryption

Historical Context:

• End-to-End Encryption: Previously encrypted messages between clients
• Protocol Change: End-to-end encryption removed in I2P
• Current Usage: Use get/setEncryptedData() methods instead
• I2CP Focus: Now mainly used for I2CP message transport

Current Structure:

• Encrypted Data: Primary payload content for transmission
• Unencrypted Data: Legacy support for decrypted content access
• Size Limits: Maximum 64KB to prevent OOM attacks
• Format Compliance: Follows I2P data structure specification

Usage Patterns:

• Modern Usage: Use getEncryptedData()/setEncryptedData() for payload
• I2CP Messages: Transport messages between client and router
• Legacy Support: getUnencryptedData() for backward compatibility
• Size Management: Monitor payload size to prevent resource exhaustion

Security Considerations:

• Size Validation: Enforce 64KB maximum payload size
• Memory Protection: Prevent OOM attacks through large payloads
• Content Validation: Verify payload integrity and format
• Encryption Context: Understand current encryption model in I2P

Performance Aspects:

• Efficient Storage: Minimal overhead for payload data
• Fast Access: Direct byte array access methods
• Memory Management: Careful allocation and cleanup
• Size Checking: Quick validation of payload limits

Migration Notes:

• From End-to-End: Previously handled client-to-client encryption
• To Transport Only: Now focuses on message transport
• API Simplification: Use encrypted data methods for clarity
• Backward Compatibility: Legacy methods still available

See Also:

Serialized Form

Constructor Summary

Constructors

Constructor and Description
Payload()

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object object)
byte[]	getEncryptedData() the real data
int	getSize()
byte[]	getUnencryptedData() Retrieve the unencrypted body of the message.
int	hashCode()
void	readBytes(InputStream in) Load up the current object with data from the given stream.
void	setEncryptedData(byte[] data) the real data
void	setUnencryptedData(byte[] data) Populate the message body with data.
String	toString()
int	writeBytes(byte[] target, int offset) Writes the encrypted payload to the target array.
void	writeBytes(OutputStream out) Write out the data structure to the stream, using the format defined in the I2P data structure specification.

Methods inherited from class net.i2p.data.DataStructureImpl

calculateHash, fromBase64, fromByteArray, read, toBase64, toByteArray

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Payload

public Payload()

Method Detail

equals

public boolean equals(Object object)

Overrides:

equals in class Object

getEncryptedData

public byte[] getEncryptedData()

the real data

getSize

public int getSize()

getUnencryptedData

public byte[] getUnencryptedData()

Retrieve the unencrypted body of the message. Deprecated. Unless you are doing encryption, use getEncryptedData() instead.

Returns:

body of the message, or null if the message has either not been decrypted yet or if the hash is not correct

hashCode

public int hashCode()

Overrides:

hashCode in class Object

readBytes

public void readBytes(InputStream in)
               throws DataFormatException,
                      IOException

Description copied from interface: DataStructure

Load up the current object with data from the given stream. Data loaded this way must match the I2P data structure specification. Warning - many classes will throw IllegalStateException if data is already set.

Parameters:

in - stream to read from

Throws:

DataFormatException - if the data is improperly formatted

IOException - if there was a problem reading the stream

setEncryptedData

public void setEncryptedData(byte[] data)

the real data

Throws:

IllegalArgumentException - if bigger than 64KB

setUnencryptedData

public void setUnencryptedData(byte[] data)

Populate the message body with data. This does not automatically encrypt yet. Deprecated. Unless you are doing encryption, use setEncryptedData() instead.

Throws:

IllegalArgumentException - if bigger than 64KB

toString

public String toString()

Overrides:

toString in class Object

writeBytes

public int writeBytes(byte[] target,
                      int offset)

Writes the encrypted payload to the target array.

Returns:

the written length (NOT the new offset)

writeBytes

public void writeBytes(OutputStream out)
                throws DataFormatException,
                       IOException

Description copied from interface: DataStructure

Write out the data structure to the stream, using the format defined in the I2P data structure specification.

Parameters:

out - stream to write to

Throws:

DataFormatException - if the data was incomplete or not yet ready to be written

IOException - if there was a problem writing to the stream