net.i2p.data

Class Lease

java.lang.Object

net.i2p.data.DataStructureImpl

net.i2p.data.Lease

All Implemented Interfaces:

Serializable, DataStructure

Direct Known Subclasses:

Lease2, MetaLease

public class Lease
extends DataStructureImpl

Authorization grant proving a router/tunnel may receive messages for a destination.

Lease represents the fundamental routing authorization in I2P:

• Authorization: Proves specific router can receive messages
• Time-Bound: Valid only for specified time period
• Destination-Specific: Authorizes service for particular destination
• Tunnel Endpoint: Identifies specific tunnel on gateway router

Key Components:

• Gateway: Hash identifying the router hosting the tunnel
• Tunnel ID: TunnelId identifying specific tunnel on gateway
• End Time: long timestamp when lease expires

Authorization Model:

• Proof of Authority: Destination authorizes specific router
• Time Limitation: Authorization expires after set duration
• Tunnel Specificity: Authorizes particular tunnel, not all tunnels
• Renewable: Leases can be refreshed before expiration

Usage in LeaseSet:

• Multiple Leases: Destinations typically have several concurrent leases
• Load Balancing: Multiple leases distribute message load
• Redundancy: Backup tunnels if primary becomes unavailable
• Mobility: Leases updated as destination moves between routers

Network Operations:

• Message Routing: Routers use leases to forward messages
• Tunnel Selection: Senders choose from available leases
• Expiration Handling: Leases removed when they expire
• LeaseSet Publication: Leases published to network database

Security Considerations:

• Verification: Verify lease authenticity via LeaseSet signature
• Expiration: Ensure leases are still valid before use
• Gateway Trust: Verify gateway router is trusted
• Tunnel Security: Ensure tunnel endpoint is secure

Performance Aspects:

• Efficient Lookup: Hash-based gateway identification
• Quick Expiration: Timestamp comparison for validity checks
• Compact Storage: Minimal data structure for network transmission
• Fast Comparison: Optimized equals() and hashCode() methods

Related Structures:

• LeaseSet - Container for multiple leases
• Lease2 - Enhanced version with 4-byte timestamps
• MetaLease - References other LeaseSets instead of tunnels
• TunnelId - Tunnel identifier on gateway router

See Also:

Serialized Form

Field Summary

Fields

Modifier and Type	Field and Description
protected long	_end
protected Hash	_gateway
protected TunnelId	_tunnelId

Constructor Summary

Constructors

Constructor and Description
Lease()

Method Summary

Modifier and Type	Method and Description
boolean	equals(Object object)
long	getEndTime() Gets the lease end time.
Hash	getGateway() Retrieve the router at which the destination can be contacted
TunnelId	getTunnelId() Tunnel on the gateway to communicate with
int	hashCode()
boolean	isExpired() has this lease already expired?
boolean	isExpired(long fudgeFactor) has this lease already expired (giving allowing up the fudgeFactor milliseconds for clock skew)?
void	readBytes(InputStream in) Load up the current object with data from the given stream.
void	setEndDate(long date) Sets the lease end date.
void	setGateway(Hash ident) Configure the router at which the destination can be contacted
void	setTunnelId(TunnelId id) Configure the tunnel on the gateway to communicate with
String	toString()
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

Field Detail

_end

protected long _end

_gateway

protected Hash _gateway

_tunnelId

protected TunnelId _tunnelId

Constructor Detail

Lease

public Lease()

Method Detail

equals

public boolean equals(Object object)

Overrides:

equals in class Object

getEndTime

public long getEndTime()

Gets the lease end time.

getGateway

public Hash getGateway()

Retrieve the router at which the destination can be contacted

Returns:

identity of the router acting as a gateway

getTunnelId

public TunnelId getTunnelId()

Tunnel on the gateway to communicate with

Returns:

tunnel ID

hashCode

public int hashCode()

Overrides:

hashCode in class Object

isExpired

public boolean isExpired()

has this lease already expired?

isExpired

public boolean isExpired(long fudgeFactor)

has this lease already expired (giving allowing up the fudgeFactor milliseconds for clock skew)?

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

setEndDate

public void setEndDate(long date)

Sets the lease end date.

setGateway

public void setGateway(Hash ident)

Configure the router at which the destination can be contacted

Parameters:

ident - router acting as the gateway

setTunnelId

public void setTunnelId(TunnelId id)

Configure the tunnel on the gateway to communicate with

Parameters:

id - tunnel ID

toString

public String toString()

Overrides:

toString in class Object

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