net.i2p.data

Class TunnelId

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

Constructor Summary

Constructors

Constructor and Description
TunnelId()
TunnelId(long id)

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object obj)
long	getTunnelId()
int	hashCode()
void	readBytes(InputStream in)
void	setTunnelId(long id) Sets the tunnel ID for this lease.
String	toString()
void	writeBytes(OutputStream out)

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

See Also:

Constant Field Values

Constructor Detail

TunnelId

public TunnelId()

TunnelId

public TunnelId(long id)

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()

hashCode

public int hashCode()

Overrides:

hashCode in class Object

readBytes

public void readBytes(InputStream in)
               throws DataFormatException,
                      IOException

Throws:

DataFormatException

IOException

setTunnelId

public 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

Throws:

DataFormatException

IOException