i2pplus

I2P Router (`router/`)

The router module implements the core I2P router: tunnel management, transport protocols, peer selection, network database, garlic routing, and client session management. It is the central engine that all applications and services depend on.

Structure

Directory	Description
`java/src/net/i2p/router/`	Router core: lifecycle, job queue, statistics, configuration, throttling
`java/src/net/i2p/router/client/`	I2CP client session management (sessions, message routing, lease sets)
`java/src/net/i2p/router/crypto/`	Router-level crypto: ElGamal/AES engine, ratchet, transient session keys
`java/src/net/i2p/router/message/`	Garlic message building, parsing, clove sets, outbound delivery
`java/src/net/i2p/router/networkdb/`	Kademlia DHT, floodfill, iterative lookups, reseed, data stores
`java/src/net/i2p/router/peermanager/`	Peer profiling, capacity/speed calculators, profile organizer
`java/src/net/i2p/router/startup/`	Router initialization, client app loading, RouterInfo creation
`java/src/net/i2p/router/sybil/`	Sybil attack detection and mitigation
`java/src/net/i2p/router/tasks/`	Background tasks: watchdog, stats coalescing, graceful shutdown
`java/src/net/i2p/router/time/`	NTP client for clock synchronization
`java/src/net/i2p/router/transport/`	NTCP2 and SSU2 transport protocols, bandwidth limiter, GeoIP
`java/src/net/i2p/router/tunnel/`	Tunnel building, dispatch, encryption/decryption at each hop
`java/src/net/i2p/router/util/`	Router-specific utilities
`java/src/net/i2p/router/dummy/`	Stub facades for testing and embedded builds
`doc/`	Router documentation
`locale/`	Translation `.po` files
`peerProfiles/`	Persistent peer profile storage

Key Packages

net.i2p.router - Router lifecycle, RouterContext, job queue, Tuner (automatic tunnel parameter tuning), BanLogger, statistics
net.i2p.router.client - I2CP protocol implementation: ClientManager, ClientWriterRunner, session creation, lease set requests
net.i2p.router.crypto - ElGamalAESEngine (garlic encryption), TransientSessionKeyManager, FamilyKeyCrypto, PQ ratchet
net.i2p.router.message - Garlic message construction (GarlicMessageBuilder), parsing, clove routing, outbound client message jobs
net.i2p.router.networkdb - KademliaNetworkDatabaseFacade, FloodOnlySearchJob, IterativeSearchJob, StoreJob, PersistentDataStore
net.i2p.router.networkdb.reseed - Bootstrap reseed from trusted routers (Reseeder)
net.i2p.router.peermanager - PeerProfile, ProfileOrganizer, CapacityCalculator, SpeedCalculator, peer test
net.i2p.router.transport - NTCP2 (NTCPTransport) and SSU2 (UDPTransport) outbound/inbound connections, CommSystemFacadeImpl, bandwidth limiting
net.i2p.router.tunnel - TunnelDispatcher, HopProcessor, FragmentHandler, TunnelGateway (per-hop encryption and message forwarding)
net.i2p.router.tunnel.pool - TunnelPool, BuildExecutor, TestJob, ExpireJob, BuildRequestor, TunnelPeerSelector (pool lifecycle, build storms, collapse detection)
net.i2p.router.sybil - Sybil attack detection (SybilRenderer)

Key Classes

Class	Purpose
`Router`	Main router class: startup, shutdown, configuration, lifecycle
`RouterContext`	Shared context: config, stats, crypto, peer management
`Tuner`	Automatic tunnel parameter tuning based on observed metrics
`JobQueue` / `JobQueueRunner`	Job scheduling and execution framework
`TunnelManagerFacade`	Interface for tunnel pool management
`BuildExecutor`	Orchestrates concurrent tunnel builds across all pools
`TunnelPool`	Per-destination tunnel pool: build, test, expire, select
`TunnelDispatcher`	Per-hop message forwarding, encryption/decryption
`CommSystemFacadeImpl`	Transport management: NTCP2/SSU2 connections, GeoIP
`PeerManager` / `ProfileOrganizer`	Peer selection, profiling, capacity/speed scoring
`FloodfillNetworkDatabaseFacade`	Kademlia DHT with floodfill: store, lookup, explore
`GarlicMessageBuilder`	Garlic message construction and encryption
`ClientManager`	I2CP client session lifecycle and message routing
`BanLogger` / `Banlist`	Peer banning and abuse tracking

Building

# Ant (from repo root)
ant updaterCompact

# Clean build
ant distclean && ant updaterCompact

Configuration

Router configuration lives in router.config and is managed through the console web UI (/configadvanced). Key settings include bandwidth limits, transport protocols, tunnel parameters, and peer selection policies. The Tuner class automatically adjusts tunnel parameters based on observed network conditions.