Payload (Javadocs [I2P+ 2.13.0+] - API Version 0.9.70+)

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()
Required for deserialization.

Constructors
Constructor and Description
`Payload()` Required for deserialization.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object object)` Compares this payload with another object for equality.
`byte[]`	`getEncryptedData()` Encrypted data, or null.
`int`	`getSize()` Size in bytes.
`byte[]`	`getUnencryptedData()` Retrieve the unencrypted body of the message.
`int`	`hashCode()` Hash code based on the encrypted or unencrypted data.
`void`	`readBytes(InputStream in)` Reads this payload from an input stream (4-byte length-prefixed data).
`void`	`setEncryptedData(byte[] data)` the real data
`void`	`setUnencryptedData(byte[] data)` Populate the message body with data.
`String`	`toString()` Returns a string representation of this payload.
`int`	`writeBytes(byte[] target, int offset)` Writes the encrypted payload to the target array.
`void`	`writeBytes(OutputStream out)` Writes this payload to an output stream (4-byte length-prefixed data).

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()
```
    Required for deserialization.
- Method Detail
  - equals
```
public boolean equals(Object object)
```
    Compares this payload with another object for equality.
    Overrides:
    equals in class Object
  - getEncryptedData
```
public byte[] getEncryptedData()
```
    Encrypted data, or null.
    Returns:
    the encrypted data, or null
  - getSize
```
public int getSize()
```
    Size in bytes.
    Returns:
    the size in bytes
  - 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()
```
    Hash code based on the encrypted or unencrypted data.
    Overrides:
    hashCode in class Object
  - readBytes
```
public void readBytes(InputStream in)
               throws DataFormatException,
                      IOException
```
    Reads this payload from an input stream (4-byte length-prefixed data).
    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
    Parameters:
    data - the 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.
    Parameters:
    data - the data
    Throws:
    IllegalArgumentException - if bigger than 64KB
  - toString
```
public String toString()
```
    Returns a string representation of this payload.
    Overrides:
    toString in class Object
  - writeBytes
```
public int writeBytes(byte[] target,
                      int offset)
```
    Writes the encrypted payload to the target array.
    Parameters:
    target - the target
    offset - the offset
    Returns:
    the written length (NOT the new offset)
  - writeBytes
```
public void writeBytes(OutputStream out)
                throws DataFormatException,
                       IOException
```
    Writes this payload to an output stream (4-byte length-prefixed data).
    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

Class Payload

Constructor Summary

Method Summary

Methods inherited from class net.i2p.data.DataStructureImpl

Methods inherited from class java.lang.Object

Constructor Detail

Payload

Method Detail

equals

getEncryptedData

getSize

getUnencryptedData

hashCode

readBytes

setEncryptedData

setUnencryptedData

toString

writeBytes

writeBytes