TransportUtil (Javadocs [I2P+ 2.13.0+]

java.lang.Object
- net.i2p.router.transport.TransportUtil

```
public abstract class TransportUtil
extends Object
```
Utility class providing common transport operations and configurations. This class contains static methods and constants used throughout the transport system for address validation, port management, IPv6 configuration, and network utility functions. Key Features:
- IPv4 and IPv6 address validation and parsing
- Port range validation and assignment
- IPv6 configuration options for transports
- Firewall and NAT detection utilities
- Geographic IP filtering and validation
- Transport-specific constants and defaults
IPv6 Support:
- Configuration options for NTCP and SSU transports
- Address format validation for IPv6
- Port assignment and range checking
- Compatibility helpers for mixed IPv4/IPv6 environments
Network Utilities:
- Port assignment strategies (random vs. configured)
- Firewall detection and bypass methods
- Transport protocol constants and defaults
- Address type detection and validation

Nested Class Summary
Nested Classes
Modifier and Type Class and Description
static class TransportUtil.IPv6Config
IPv6 configuration options for transports.

Nested Classes
Modifier and Type	Class and Description
`static class`	`TransportUtil.IPv6Config` IPv6 configuration options for transports.

Field Summary

Fields
Modifier and Type	Field and Description
`static TransportUtil.IPv6Config`	`DEFAULT_IPV6_CONFIG` DEFAULT_IPV6_CONFIG.
`static String`	`NTCP_IPV6_CONFIG` NTCP_IPV6_CONFIG.
`static String`	`PROP_IPV4_FIREWALLED` PROP_IPV4_FIREWALLED.
`static String`	`PROP_IPV6_FIREWALLED`
`static String`	`SSU_IPV6_CONFIG` SSU_IPV6_CONFIG.

Constructor Summary
Constructors
Constructor and Description
TransportUtil()

Constructors
Constructor and Description
`TransportUtil()`

Method Summary

All Methods Static Methods Concrete Methods
Modifier and Type	Method and Description
`static TransportUtil.IPv6Config`	`getIPv6Config(RouterContext ctx, String transportStyle)`
`static TransportUtil.IPv6Config`	`getIPv6Config(String cfg)`
`static AddressType`	`getType(byte[] ip)`
`static AddressType`	`getType(RouterAddress addr)`
`static AddressType`	`getType(String host)`
`static boolean`	`isIPv4Firewalled(RouterContext ctx)` This returns true if the force-firewalled setting is configured, false otherwise.
`static boolean`	`isIPv6(RouterAddress addr)` Addresses without a host (i.e.
`static boolean`	`isIPv6Firewalled(RouterContext ctx)` This returns true if the force-firewalled setting is configured, false otherwise.
`static boolean`	`isPubliclyRoutable(byte[] addr, boolean allowIPv6)`
`static boolean`	`isPubliclyRoutable(byte[] addr, boolean allowIPv4, boolean allowIPv6)` Ref: RFC 5735
`static boolean`	`isValidPort(int port)` Is this a valid port for us or a remote router? ref: http://i2p-projekt.i2p/en/docs/ports ref: https://cs.chromium.org/chromium/src/net/base/port_util.cc
`static boolean`	`isYggdrasil(RouterAddress addr)`
`static void`	`logInvalidPort(Log log, String transportStyle, int port)` log an error
`static int`	`selectRandomPort(RouterContext ctx, String transportStyle)` Pick a random port between the configured boundaries

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

Field Detail
- DEFAULT_IPV6_CONFIG
```
public static final TransportUtil.IPv6Config DEFAULT_IPV6_CONFIG
```
  DEFAULT_IPV6_CONFIG.
- NTCP_IPV6_CONFIG
```
public static final String NTCP_IPV6_CONFIG
```
  NTCP_IPV6_CONFIG.
  See Also:
  Constant Field Values
- PROP_IPV4_FIREWALLED
```
public static final String PROP_IPV4_FIREWALLED
```
  PROP_IPV4_FIREWALLED.
  See Also:
  Constant Field Values
- PROP_IPV6_FIREWALLED
```
public static final String PROP_IPV6_FIREWALLED
```
  See Also:
  Constant Field Values
- SSU_IPV6_CONFIG
```
public static final String SSU_IPV6_CONFIG
```
  SSU_IPV6_CONFIG.
  See Also:
  Constant Field Values

Constructor Detail
- TransportUtil
```
public TransportUtil()
```

Method Detail

getIPv6Config

public static TransportUtil.IPv6Config getIPv6Config(RouterContext ctx,
                                                     String transportStyle)

Returns:: the i pv6 config

getIPv6Config

public static TransportUtil.IPv6Config getIPv6Config(String cfg)

Returns:: the i pv6 config

getType

public static AddressType getType(byte[] ip)

Returns:: null if unknown

getType

public static AddressType getType(RouterAddress addr)

Returns:: null if unknown

getType

public static AddressType getType(String host)

Returns:: null if unknown

isIPv4Firewalled
```
public static boolean isIPv4Firewalled(RouterContext ctx)
```
This returns true if the force-firewalled setting is configured, false otherwise.
Returns:
whether i pv4 firewalled

isIPv6
```
public static boolean isIPv6(RouterAddress addr)
```
Addresses without a host (i.e. w/introducers) are assumed to be IPv4 unless a '6' cap is present
Parameters:
addr - non-null
Returns:
whether i pv6

isIPv6Firewalled
```
public static boolean isIPv6Firewalled(RouterContext ctx)
```
This returns true if the force-firewalled setting is configured, false otherwise.
Returns:
whether i pv6 firewalled

isPubliclyRoutable

public static boolean isPubliclyRoutable(byte[] addr,
                                         boolean allowIPv6)

Parameters:: addr - non-null
Returns:: whether publicly routable

isPubliclyRoutable

public static boolean isPubliclyRoutable(byte[] addr,
                                         boolean allowIPv4,
                                         boolean allowIPv6)

Ref: RFC 5735

Parameters:: addr - non-null
Returns:: whether publicly routable

isValidPort
```
public static boolean isValidPort(int port)
```
Is this a valid port for us or a remote router? ref: http://i2p-projekt.i2p/en/docs/ports ref: https://cs.chromium.org/chromium/src/net/base/port_util.cc
Returns:
whether valid port

isYggdrasil

public static boolean isYggdrasil(RouterAddress addr)

Returns:: whether yggdrasil

logInvalidPort

public static void logInvalidPort(Log log,
                                  String transportStyle,
                                  int port)

log an error

selectRandomPort

public static int selectRandomPort(RouterContext ctx,
                                   String transportStyle)

Pick a random port between the configured boundaries

Class TransportUtil

Nested Class Summary

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

DEFAULT_IPV6_CONFIG

NTCP_IPV6_CONFIG

PROP_IPV4_FIREWALLED

PROP_IPV6_FIREWALLED

SSU_IPV6_CONFIG

Constructor Detail

TransportUtil

Method Detail

getIPv6Config

getIPv6Config

getType

getType

getType

isIPv4Firewalled

isIPv6

isIPv6Firewalled

isPubliclyRoutable

isPubliclyRoutable

isValidPort

isYggdrasil

logInvalidPort

selectRandomPort