org.restcomm.media.stun.messages.attributes.address

Class XorMappedAddressAttribute

java.lang.Object

org.restcomm.media.stun.messages.attributes.StunAttribute

org.restcomm.media.stun.messages.attributes.address.AddressAttribute

org.restcomm.media.stun.messages.attributes.address.XorMappedAddressAttribute

Direct Known Subclasses:

XorPeerAddressAttribute, XorRelayedAddressAttribute

public class XorMappedAddressAttribute
extends AddressAttribute

The XOR-MAPPED-ADDRESS attribute is only present in Binding Responses. It provides the same information that is present in the MAPPED-ADDRESS attribute. However, the information is encoded by performing an exclusive or (XOR) operation between the mapped address and the transaction ID. Unfortunately, some NAT devices have been found to rewrite binary encoded IP addresses and ports that are present in protocol payloads. This behavior interferes with the operation of STUN. By providing the mapped address in an obfuscated form, STUN can continue to operate through these devices. The format of the XOR-MAPPED-ADDRESS is: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |x x x x x x x x| Family | X-Port | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | X-Address (Variable) +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ The Family represents the IP address family, and is encoded identically to the Family in MAPPED-ADDRESS. X-Port is equal to the port in MAPPED-ADDRESS, exclusive or'ed with most significant 16 bits of the transaction ID. If the IP address family is IPv4, X-Address is equal to the IP address in MAPPED- ADDRESS, exclusive or'ed with the most significant 32 bits of the transaction ID. If the IP address family is IPv6, the X-Address is equal to the IP address in MAPPED-ADDRESS, exclusive or'ed with the entire 128 bit transaction ID.

Field Summary

Fields

Modifier and Type	Field and Description
static String	NAME

Fields inherited from class org.restcomm.media.stun.messages.attributes.address.AddressAttribute

ADDRESS_FAMILY_IPV4, ADDRESS_FAMILY_IPV6, transportAddress

Fields inherited from class org.restcomm.media.stun.messages.attributes.StunAttribute

ALTERNATE_SERVER, attributeType, CHANGE_REQUEST, CHANGED_ADDRESS, CHANNEL_NUMBER, DATA, DESTINATION_ADDRESS, DONT_FRAGMENT, ERROR_CODE, EVEN_PORT, FINGERPRINT, HEADER_LENGTH, ICE_CONTROLLED, ICE_CONTROLLING, LIFETIME, MAGIC_COOKIE, MAPPED_ADDRESS, MESSAGE_INTEGRITY, NONCE, PASSWORD, PRIORITY, REALM, REFLECTED_FROM, REMOTE_ADDRESS, REQUESTED_TRANSPORT, RESERVATION_TOKEN, RESPONSE_ADDRESS, SOFTWARE, SOURCE_ADDRESS, UNKNOWN_ATTRIBUTES, UNKNOWN_OPTIONAL_ATTRIBUTE, USE_CANDIDATE, USERNAME, XOR_MAPPED_ADDRESS, XOR_ONLY, XOR_PEER_ADDRESS, XOR_RELAYED_ADDRESS

Constructor Summary

Constructors

Modifier	Constructor and Description
	XorMappedAddressAttribute()
protected	XorMappedAddressAttribute(char type)

Method Summary

Methods

Modifier and Type	Method and Description
TransportAddress	applyXor(byte[] xorMask) Returns the result of applying XOR on this attribute's address, using the specified XOR mask.
static TransportAddress	applyXor(TransportAddress address, byte[] transactionID) Returns the result of applying XOR on the specified attribute's address.
TransportAddress	getAddress(byte[] transactionID) Returns the result of applying XOR on this attribute's address, using the specified transaction ID when converting IPv6 addresses.
String	getName() Returns the human readable name of this attribute.
void	setAddress(TransportAddress address, byte[] transactionID) Applies a XOR mask to the specified address and then sets it as the value transported by this attribute.

Methods inherited from class org.restcomm.media.stun.messages.attributes.address.AddressAttribute

decodeAttributeBody, encode, equals, getAddress, getAddressBytes, getDataLength, getFamily, getPort, setAddress, setAttributeType

Methods inherited from class org.restcomm.media.stun.messages.attributes.StunAttribute

getAttributeType, getLocationInMessage, setLocationInMessage

Methods inherited from class java.lang.Object

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

Field Detail

NAME

public static final String NAME

See Also:

Constant Field Values

Constructor Detail

XorMappedAddressAttribute

public XorMappedAddressAttribute()

XorMappedAddressAttribute

protected XorMappedAddressAttribute(char type)

Method Detail

applyXor

public static TransportAddress applyXor(TransportAddress address,
                        byte[] transactionID)

Returns the result of applying XOR on the specified attribute's address. The method may be used for both encoding and decoding XorMappedAddresses.

Parameters:

address - the address on which XOR should be applied

transactionID - the transaction id to use for the XOR

Returns:

the XOR-ed address.

getAddress

public TransportAddress getAddress(byte[] transactionID)

Returns the result of applying XOR on this attribute's address, using the specified transaction ID when converting IPv6 addresses.

Parameters:

transactionID - the transaction ID to use in case this attribute is encapsulating an IPv6 address.

Returns:

the XOR-ed address.

applyXor

public TransportAddress applyXor(byte[] xorMask)

Returns the result of applying XOR on this attribute's address, using the specified XOR mask. The method may be used for both encoding and decoding XorMappedAddresses.

Parameters:

xorMask - the XOR mask to use when obtaining the original address.

Returns:

the XOR-ed address.

setAddress

public void setAddress(TransportAddress address,
              byte[] transactionID)

Applies a XOR mask to the specified address and then sets it as the value transported by this attribute.

Parameters:

address - the address that we should xor and then record in this attribute.

transactionID - the transaction identifier that we should use when creating the XOR mask.

getName

public String getName()

Description copied from class: StunAttribute

Returns the human readable name of this attribute. Attribute names do not really matter from the protocol point of view. They are only used for debugging and readability.

Specified by:

getName in class StunAttribute

Returns:

this attribute's name.