Package 

Class XorMappedAddressAttribute

  • All Implemented Interfaces:
    
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.

    • Nested Class Summary

      Nested Classes 
      Modifier and Type Class Description

    • Field Summary

      Fields 
      Modifier and Type Field Description
      public final static String NAME

    • Constructor Summary

      Constructors 
      Constructor Description

    • Enum Constant Summary

      Enum Constants 
      Enum Constant Description

    • Method Summary

      Modifier and Type Method Description
      static TransportAddress applyXor(TransportAddress address, Array<byte> transactionID) Returns the result of applying XOR on the specified attribute's address.
      TransportAddress getAddress(Array<byte> transactionID) Returns the result of applying XOR on this attribute's address, using the specified transaction ID when converting IPv6 addresses.
      TransportAddress applyXor(Array<byte> xorMask) Returns the result of applying XOR on this attribute's address, using the specified XOR mask.
      void setAddress(TransportAddress address, Array<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.ice4j.attribute.AddressAttribute

        encode, equals, getAddress, getAddressBytes, getDataLength, getFamily, getName, getPort, setAddress

      • Methods inherited from class org.ice4j.attribute.Attribute

        getAttributeType, getLocationInMessage, setLocationInMessage

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

    • Method Detail

      • applyXor

         static TransportAddress applyXor(TransportAddress address, Array<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

      • getAddress

         TransportAddress getAddress(Array<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.

      • applyXor

         TransportAddress applyXor(Array<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.

      • setAddress

         void setAddress(TransportAddress address, Array<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.