net.i2p.router.transport

Class TransportManager

java.lang.Object

net.i2p.router.transport.TransportManager

All Implemented Interfaces:

TransportEventListener

public class TransportManager
extends Object
implements TransportEventListener

Central coordinator for all I2P transport protocols. This class manages the lifecycle, configuration, and coordination of all enabled transport protocols (NTCP, UDP, SSU, etc.). It provides unified access to transport functionality and handles transport-specific operations like address management, peer discovery, and message routing. Core Responsibilities:

• Transport lifecycle management (start/stop/restart)
• Address discovery and configuration
• Peer connection management and statistics
• Message routing between transports
• UPnP integration for NAT traversal
• Bandwidth allocation and coordination
• Transport event handling and notifications

Transport Support:

• Built-in transports: NTCP, UDP, SSU
• Pluggable transport support (incomplete)
• IPv4 and IPv6 addressing
• Automatic transport selection and failover

UPnP Integration: Automatically starts and manages UPnP service for NAT traversal and port forwarding discovery. API Access: This class is primarily internal to the router. Only a few methods are public for console and Android integration. External components should use CommSystemFacadeImpl for transport access rather than calling this class directly. Note: This is not intended as a public API for external use. Implementation details may change without notice.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
(package private) static class	TransportManager.Port Port configuration for transport protocols.

Field Summary

Fields

Modifier and Type	Field and Description
static boolean	DEFAULT_ENABLE_UPNP_IPV6
static String	PROP_ENABLE_NTCP default true
static String	PROP_ENABLE_UDP default true
static String	PROP_ENABLE_UPNP default true
static String	PROP_ENABLE_UPNP_IPV6

Constructor Summary

Constructors

Constructor and Description
TransportManager(RouterContext context)

Method Summary

Modifier and Type	Method and Description
(package private) int	countActivePeers() How many peers are we currently connected to, that we have sent a message to or received a message from in the last five minutes.
(package private) int	countActiveSendPeers() How many peers are we currently connected to, that we have sent a message to in the last minute.
(package private) void	externalAddressReceived(Transport.AddressSource source, byte[] ip, int port) Initialize from interfaces, and callback from UPnP or SSU.
(package private) void	externalAddressRemoved(Transport.AddressSource source, boolean ipv6) Remove all ipv4 or ipv6 addresses.
(package private) void	forceDisconnect(Hash peer) Tell the transports to disconnect from this peer.
(package private) void	forwardPortStatus(String style, byte[] ip, int port, int externalPort, boolean success, String reason) callback from UPnP
(package private) List<RouterAddress>	getAddresses() This forces a rebuild
(package private) TransportBid	getBid(OutNetMessage msg)
(package private) List<TransportBid>	getBids(OutNetMessage msg)
(package private) List<Long>	getClockSkews() Return our peer clock skews on all transports.
List<Hash>	getEstablished() Get list of peers with established connections across all transports.
byte[]	getIP(Hash peer) IP of the peer from the last connection (in or out, any transport).
(package private) List<String>	getMostRecentErrorMessages()
(package private) TransportBid	getNextBid(OutNetMessage msg)
(package private) CommSystemFacade.Status	getReachabilityStatus() Previously returned short, now enum as of 0.9.20
(package private) Transport	getTransport(String style)
(package private) int	getTransportCount()
(package private) SortedMap<String,Transport>	getTransports()
(package private) X25519KeyFactory	getXDHFactory() Get the X25519 key factory used by transports.
(package private) boolean	haveHighOutboundCapacity() Are all transports well below their outbound connection limit Use for throttling in the router.
(package private) boolean	haveInboundCapacity(int pct) Is at least one transport below its inbound connection limit + some margin Use for throttling in the router.
(package private) boolean	haveOutboundCapacity(int pct) Is at least one transport below its outbound connection limit + some margin Use for throttling in the router.
(package private) void	initializeAddress() Notify all transports of ALL routable interface addresses, including IPv6.
(package private) boolean	isBacklogged(Hash peer)
(package private) boolean	isEstablished(Hash peer)
static boolean	isNTCPEnabled(RouterContext ctx)
(package private) void	mayDisconnect(Hash peer) Tell the transports that we may disconnect from this peer.
void	messageReceived(I2NPMessage message, RouterIdentity fromRouter, Hash fromRouterHash) Handle incoming I2NP message from a peer.
(package private) void	registerAndStart(Transport t) Register and start a pluggable transport.
void	renderStatusHTML(Writer out, String urlBase, int sortFlags) Render transport status information as HTML for console display.
(package private) void	restart()
(package private) void	shutdown() Cannot be restarted.
(package private) void	startListening()
(package private) void	stopAndUnregister(Transport t) Stop and unregister a pluggable transport.
(package private) void	stopListening() Can be restarted.
void	transportAddressChanged() Handle transport address change notifications.
(package private) boolean	wasUnreachable(Hash peer) Was the peer UNreachable (outbound only) on any transport, based on the last time we tried it for each transport? This is NOT reset if the peer contacts us.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DEFAULT_ENABLE_UPNP_IPV6

public static final boolean DEFAULT_ENABLE_UPNP_IPV6

See Also:

Constant Field Values

PROP_ENABLE_NTCP

public static final String PROP_ENABLE_NTCP

default true

See Also:

Constant Field Values

PROP_ENABLE_UDP

public static final String PROP_ENABLE_UDP

default true

See Also:

Constant Field Values

PROP_ENABLE_UPNP

public static final String PROP_ENABLE_UPNP

default true

See Also:

Constant Field Values

PROP_ENABLE_UPNP_IPV6

public static final String PROP_ENABLE_UPNP_IPV6

See Also:

Constant Field Values

Constructor Detail

TransportManager

public TransportManager(RouterContext context)

Method Detail

countActivePeers

int countActivePeers()

How many peers are we currently connected to, that we have sent a message to or received a message from in the last five minutes.

countActiveSendPeers

int countActiveSendPeers()

How many peers are we currently connected to, that we have sent a message to in the last minute. Unused for anything, to be removed.

externalAddressReceived

void externalAddressReceived(Transport.AddressSource source,
                             byte[] ip,
                             int port)

Initialize from interfaces, and callback from UPnP or SSU. See CSFI.notifyReplaceAddress(). Tell all transports... but don't loop.

externalAddressRemoved

void externalAddressRemoved(Transport.AddressSource source,
                            boolean ipv6)

Remove all ipv4 or ipv6 addresses. See CSFI.notifyRemoveAddress(). Tell all transports... but don't loop.

forceDisconnect

void forceDisconnect(Hash peer)

Tell the transports to disconnect from this peer.

forwardPortStatus

void forwardPortStatus(String style,
                       byte[] ip,
                       int port,
                       int externalPort,
                       boolean success,
                       String reason)

callback from UPnP

getAddresses

List<RouterAddress> getAddresses()

This forces a rebuild

getBid

TransportBid getBid(OutNetMessage msg)

getBids

List<TransportBid> getBids(OutNetMessage msg)

getClockSkews

List<Long> getClockSkews()

Return our peer clock skews on all transports. List composed of Long, each element representing a peer skew in seconds. A positive number means our clock is ahead of theirs. Note: this method returns them in whimsical order.

getEstablished

public List<Hash> getEstablished()

Get list of peers with established connections across all transports. This method aggregates established peers from all active transports (NTCP, UDP, SSU, etc.) to provide a unified view of the router's current peer connections.

Returns:

list of peer hashes with established connections, may be empty if no connections exist

getIP

public byte[] getIP(Hash peer)

IP of the peer from the last connection (in or out, any transport). This may be different from that advertised in the netDb, as the peer may be hidden, or connect from a different IP, or change his netDb later, in an attempt to avoid restrictions. For blocking purposes, etc. it's worth checking both the netDb addresses and this address.

Returns:

IPv4 or IPv6 or null

getMostRecentErrorMessages

List<String> getMostRecentErrorMessages()

getNextBid

TransportBid getNextBid(OutNetMessage msg)

getReachabilityStatus

CommSystemFacade.Status getReachabilityStatus()

Previously returned short, now enum as of 0.9.20

Returns:

the best status of any transport

getTransport

Transport getTransport(String style)

getTransportCount

int getTransportCount()

getTransports

SortedMap<String,Transport> getTransports()

Returns:

SortedMap of style to Transport (a copy)

getXDHFactory

X25519KeyFactory getXDHFactory()

Get the X25519 key factory used by transports. This method returns the key factory that provides X25519 key pairs for transport encryption operations. The factory is used by NTCP and UDP transports for ephemeral key generation in session establishment.

Returns:

X25519KeyFactory instance for transport cryptography

haveHighOutboundCapacity

boolean haveHighOutboundCapacity()

Are all transports well below their outbound connection limit Use for throttling in the router.

haveInboundCapacity

boolean haveInboundCapacity(int pct)

Is at least one transport below its inbound connection limit + some margin Use for throttling in the router.

Parameters:

pct - percent of limit 0-100

haveOutboundCapacity

boolean haveOutboundCapacity(int pct)

Is at least one transport below its outbound connection limit + some margin Use for throttling in the router.

Parameters:

pct - percent of limit 0-100

initializeAddress

void initializeAddress()

Notify all transports of ALL routable interface addresses, including IPv6. It's the transport's job to ignore what it can't handle.

isBacklogged

boolean isBacklogged(Hash peer)

isEstablished

boolean isEstablished(Hash peer)

isNTCPEnabled

public static boolean isNTCPEnabled(RouterContext ctx)

mayDisconnect

void mayDisconnect(Hash peer)

Tell the transports that we may disconnect from this peer. This is advisory only.

messageReceived

public void messageReceived(I2NPMessage message,
                            RouterIdentity fromRouter,
                            Hash fromRouterHash)

Handle incoming I2NP message from a peer. This method is called by transports when they receive an I2NP message that needs to be processed by the router. The TransportManager acts as a central message dispatcher and routes messages to appropriate handlers.

Specified by:

messageReceived in interface TransportEventListener

Parameters:

message - the received I2NP message to be processed

fromRouter - identity of the sending router

fromRouterHash - hash of the sending router for quick lookup

registerAndStart

void registerAndStart(Transport t)

Register and start a pluggable transport. This method registers a new pluggable transport (not NTCP or SSU) with the transport manager and starts it if this is the first transport being registered. The method handles validation, initialization, and lifecycle management. Process:

• Validates transport is not built-in (NTCP/UDP)
• Checks for duplicate transport styles
• Adds to pluggable transport registry
• Sets transport event listener
• Initializes transport addresses
• Starts transport listening if first transport
• Rebuilds router info with new addresses

Parameters:

t - the transport to register and start

Throws:

IllegalArgumentException - if transport is built-in type

IllegalStateException - if transport style already exists

renderStatusHTML

public void renderStatusHTML(Writer out,
                             String urlBase,
                             int sortFlags)
                      throws IOException

Render transport status information as HTML for console display. This method generates detailed HTML status for all transports, including connection counts, peer information, bandwidth usage, and transport-specific statistics. The output is used by the router console for transport monitoring.

Parameters:

out - writer to write HTML output to

urlBase - base URL for generating links

sortFlags - flags controlling sorting and display options

Throws:

IOException - if writing to output fails

restart

void restart()

shutdown

void shutdown()

Cannot be restarted.

startListening

void startListening()

stopAndUnregister

void stopAndUnregister(Transport t)

Stop and unregister a pluggable transport. This method gracefully shuts down a pluggable transport (not NTCP or SSU) and removes it from the transport registry. The method handles cleanup, listener removal, and address updates. Process:

• Validates transport is not built-in (NTCP/UDP)
• Removes transport event listener
• Removes from pluggable transport registry
• Stops transport listening
• Removes from main transport registry
• Rebuilds router info without transport addresses

Parameters:

t - the transport to stop and unregister

Throws:

IllegalArgumentException - if transport is built-in type

stopListening

void stopListening()

Can be restarted.

transportAddressChanged

public void transportAddressChanged()

Handle transport address change notifications. This method is called when any transport reports a change in its advertised addresses. The TransportManager coordinates address updates across all transports and updates the router's published information accordingly. This method is typically called by transports in response to:

• UPnP address discovery
• Interface address changes
• Configuration updates
• Network topology changes

Specified by:

transportAddressChanged in interface TransportEventListener

wasUnreachable

boolean wasUnreachable(Hash peer)

Was the peer UNreachable (outbound only) on any transport, based on the last time we tried it for each transport? This is NOT reset if the peer contacts us.