org.eclipse.californium.scandium.dtls

Interface ConnectionIdGenerator

All Known Subinterfaces:

NodeConnectionIdGenerator

All Known Implementing Classes:

MultiNodeConnectionIdGenerator, SingleNodeConnectionIdGenerator

public interface ConnectionIdGenerator

Connection id generator. Responsible for generating ID which identifies scandium connections in store. By default, DTLS defined that IP address and port of the peer are used to identify the DTLS Connection. The DTLS connection ID draft defines a way to identify connection using Connection ID and so supports environments where IP address/port changes. See draft-ietf-tls-dtls-connection-id-03. The draft enables the peers to chose the level of support or usage. The dtls client peer informs the dtls server peer about its preference using a new HELLO_EXTENSION in it's CLIENT_HELLO.

The dtls client can chose:

client doesn't support it

the new extension is not included in the client hello

client supports it (but doesn't use it)

the new extension with an empty connection id (0 length) is included in the client hello

client uses it

the new extension with a non-empty connection id is included in the client hello

If the client doesn't support it, the server must reply with a server hello without the new hello extension, regardless of the configuration.

If the client supports or uses it, the server can chose.

server doesn't support it

the new extension is not included in the server hello

server supports it (but doesn't use it)

the new extension with an empty connection id (0 length) is included in the server hello

server uses it

the new extension with a non-empty connection id is included in the server hello

The behavior of a peer within the above rules could be configured using DtlsConnectorConfig.Builder.setConnectionIdGenerator(org.eclipse.californium.scandium.dtls.ConnectionIdGenerator).

do not support it

use a null as connection id generator

support it (but doesn't use it)

use a ConnectionIdGenerator, which returns false on useConnectionId()

use it

use a ConnectionIdGenerator, which returns true on useConnectionId() and generates and reads connection ids.

Method Summary

Methods

Modifier and Type	Method and Description
ConnectionId	createConnectionId() Creates a connection id.
ConnectionId	read(org.eclipse.californium.elements.util.DatagramReader reader) Read connection id from record header bytes.
boolean	useConnectionId() Indicates, if connection ids are used or just supported.

Method Detail

useConnectionId

boolean useConnectionId()

Indicates, if connection ids are used or just supported.

Returns:

true, if a connection is used, false, if only a connection id from the other peer is supported.

createConnectionId

ConnectionId createConnectionId()

Creates a connection id. The caller must take care to use only unique connection ids. In cases where the generated connection id is already in use, it's intended to create a next connection id calling this method again.

Returns:

created connection id or null, if this generator only supports connection ids from the other peer.

read

ConnectionId read(org.eclipse.californium.elements.util.DatagramReader reader)

Read connection id from record header bytes.

Parameters:

reader - reader with header bytes at the position of the connection id.

Returns:

read connection id or null, if this generator only supports connection ids from the other peer.