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

java.lang.Object
- net.i2p.data.TunnelId

```
public class TunnelId
extends Object
```
Tunnel identifier for routing messages through a sequence of routers in I2P.
TunnelId provides unique identification within tunnel routing:
- Local Uniqueness: Must be unique on each router in tunnel
- 4-Byte Value: 32-bit identifier (1 to 0xffffffff)
- Random Generation: Typically generated from cryptographically secure random
- Routing Coordination: Prevents message delivery to wrong tunnels
Constraints and Validation:
- Minimum Value: Must be greater than zero (ID > 0)
- Maximum Value: Limited to 0xffffffff (32-bit unsigned integer)
- Special Case: Zero reserved for direct replies in DatabaseStoreMessage
- Uniqueness: Router must enforce uniqueness across its tunnels
Usage in I2P:
- Tunnel Routing: Messages forwarded through tunnel chain
- Message Delivery: Ensures messages reach correct tunnel endpoint
- Tunnel Management: Creation, configuration, and teardown
- Load Balancing: Multiple tunnels for traffic distribution
- Client Communication: I2CP tunnel establishment and management
Performance Considerations:
- Efficient Storage: Compact 4-byte representation
- Fast Comparison: Optimized equals() and hashCode() methods
- Minimal Overhead: No object inheritance since 0.9.48
- Memory Efficiency: Primitive long storage
Security Aspects:
- ID Randomness: Use cryptographically secure random generation
- ID Unpredictability: Prevent tunnel ID guessing attacks
- Collision Avoidance: Local uniqueness prevents routing confusion
- Isolation: Different tunnels have separate ID spaces
Implementation Notes:
- Space Optimization: Does not extend DataStructureImpl since 0.9.48
- External Use: Not recommended for external use, subject to change
- Thread Safety: Immutable objects are inherently thread-safe
- Validation: Constructor enforces valid ID range
Constants:
- MAX_ID_VALUE - Maximum allowed tunnel ID (0xffffffff)

Field Summary
Fields
Modifier and Type Field and Description
static long MAX_ID_VALUE
Maximum tunnel ID value (2^32 - 1).

Fields
Modifier and Type	Field and Description
`static long`	`MAX_ID_VALUE` Maximum tunnel ID value (2^32 - 1).

Constructor Summary
Constructors
Constructor and Description
TunnelId()
TunnelId(long id)
1 to 0xffffffff.

Constructors
Constructor and Description
`TunnelId()`
`TunnelId(long id)` 1 to 0xffffffff.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`equals(Object obj)`
`long`	`getTunnelId()` Tunnel ID.
`int`	`hashCode()`
`void`	`readBytes(InputStream in)` Read the tunnel ID from a stream.
`void`	`setTunnelId(long id)` Sets the tunnel ID for this lease.
`String`	`toString()`
`void`	`writeBytes(OutputStream out)` Write the tunnel ID to a stream.

Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- Field Detail
  - MAX_ID_VALUE
```
public static final long MAX_ID_VALUE
```
    Maximum tunnel ID value (2^32 - 1).
    See Also:
    Constant Field Values
- Constructor Detail
  - TunnelId
```
public TunnelId()
```
  - TunnelId
```
public TunnelId(long id)
```
    1 to 0xffffffff.
    Parameters:
    id - 1 to 0xffffffff
    Throws:
    IllegalArgumentException - if less than or equal to zero or greater than max value
- Method Detail
  - equals
```
public boolean equals(Object obj)
```
    Overrides:
    equals in class Object
  - getTunnelId
```
public long getTunnelId()
```
    Tunnel ID.
    Returns:
    the tunnel ID
  - hashCode
```
public int hashCode()
```
    Overrides:
    hashCode in class Object
  - readBytes
```
public void readBytes(InputStream in)
               throws DataFormatException,
                      IOException
```
    Read the tunnel ID from a stream.
    Parameters:
    in - the input stream to read from
    Throws:
    DataFormatException - if the data is invalid
    IOException - if there is an error reading
  - setTunnelId
```
public final void setTunnelId(long id)
```
    Sets the tunnel ID for this lease.
    Parameters:
    id - 1 to 0xffffffff
    Throws:
    IllegalArgumentException - if less than or equal to zero or greater than max value
  - toString
```
public String toString()
```
    Overrides:
    toString in class Object
  - writeBytes
```
public void writeBytes(OutputStream out)
                throws DataFormatException,
                       IOException
```
    Write the tunnel ID to a stream.
    Parameters:
    out - the output stream to write to
    Throws:
    DataFormatException - if the data is invalid
    IOException - if there is an error writing

Class TunnelId

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

MAX_ID_VALUE

Constructor Detail

TunnelId

TunnelId

Method Detail

equals

getTunnelId

hashCode

readBytes

setTunnelId

toString

writeBytes