org.apache.sshd.common.kex.extension

Interface KexExtensionHandler

All Known Implementing Classes:

DefaultClientKexExtensionHandler

public interface KexExtensionHandler

Used to support RFC 8308

Author:

Apache MINA SSHD Project

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static class	KexExtensionHandler.AvailabilityPhase Provides a hint as to the context in which isKexExtensionsAvailable is invoked
static class	KexExtensionHandler.KexPhase The phase at which sendKexExtensions is invoked

Method Summary

Modifier and Type	Method and Description
default boolean	handleKexCompressionMessage(Session session, Buffer buffer) Parses the SSH_MSG_NEWCOMPRESS message.
default void	handleKexExtensionNegotiation(Session session, KexProposalOption option, String nValue, Map<KexProposalOption,String> c2sOptions, String cValue, Map<KexProposalOption,String> s2cOptions, String sValue) Invoked during the KEX negotiation phase to inform about option being negotiated.
default boolean	handleKexExtensionRequest(Session session, int index, int count, String name, byte[] data) Invoked by handleKexExtensionsMessage(Session, Buffer) in order to handle a specific extension.
default boolean	handleKexExtensionsMessage(Session session, Buffer buffer) Parses the SSH_MSG_EXT_INFO message.
default void	handleKexInitProposal(Session session, boolean initiator, Map<KexProposalOption,String> proposal) Invoked when a peer is ready to send the KEX options proposal or has received such a proposal.
default boolean	isKexExtensionsAvailable(Session session, KexExtensionHandler.AvailabilityPhase phase)
default void	sendKexExtensions(Session session, KexExtensionHandler.KexPhase phase) Invoked in order to allow the handler to send an SSH_MSG_EXT_INFO message.

Method Detail

isKexExtensionsAvailable

default boolean isKexExtensionsAvailable(Session session,
                                         KexExtensionHandler.AvailabilityPhase phase)
                                  throws IOException

Parameters:

session - The Session about to execute KEX

phase - The KexExtensionHandler.AvailabilityPhase hint as to why the query is being made

Returns:

true whether to KEX extensions are supported/allowed for the session

Throws:

IOException - If failed to process the request

handleKexInitProposal

default void handleKexInitProposal(Session session,
                                   boolean initiator,
                                   Map<KexProposalOption,String> proposal)
                            throws Exception

Invoked when a peer is ready to send the KEX options proposal or has received such a proposal. Note: this method is called during the negotiation phase even if isKexExtensionsAvailable returns false for the session.

Parameters:

session - The Session initiating or receiving the proposal

initiator - true if the proposal is about to be sent, false if this is a proposal received from the peer.

proposal - The proposal contents - Caveat emptor: the proposal is modifiable i.e., the handler can modify it before being sent or before being processed (if incoming)

Throws:

Exception - If failed to handle the request

handleKexExtensionNegotiation

default void handleKexExtensionNegotiation(Session session,
                                           KexProposalOption option,
                                           String nValue,
                                           Map<KexProposalOption,String> c2sOptions,
                                           String cValue,
                                           Map<KexProposalOption,String> s2cOptions,
                                           String sValue)
                                    throws Exception

Invoked during the KEX negotiation phase to inform about option being negotiated. Note: this method is called during the negotiation phase even if isKexExtensionsAvailable returns false for the session.

Parameters:

session - The Session executing the negotiation

option - The negotiated KexProposalOption

nValue - The negotiated option value (may be null/empty).

c2sOptions - The client proposals

cValue - The client-side value for the option (may be null/empty).

s2cOptions - The server proposals

sValue - The server-side value for the option (may be null/empty).

Throws:

Exception - If failed to handle the invocation

sendKexExtensions

default void sendKexExtensions(Session session,
                               KexExtensionHandler.KexPhase phase)
                        throws Exception

Invoked in order to allow the handler to send an SSH_MSG_EXT_INFO message. Note: this method is called only if isKexExtensionsAvailable returns true for the session.

Parameters:

session - The Session

phase - The phase at which the handler is invoked

Throws:

Exception - If failed to handle the invocation

See Also:

RFC-8308 - section 2.4

handleKexExtensionsMessage

default boolean handleKexExtensionsMessage(Session session,
                                           Buffer buffer)
                                    throws Exception

Parses the SSH_MSG_EXT_INFO message. Note: this method is called regardless of whether isKexExtensionsAvailable returns true for the session.

Parameters:

session - The Session through which the message was received

buffer - The message buffer

Returns:

true if message handled - if false then SSH_MSG_UNIMPLEMENTED will be generated

Throws:

Exception - If failed to handle the message

See Also:

RFC-8308 - section 2.3, handleKexExtensionRequest(Session, int, int, String, byte[])

handleKexCompressionMessage

default boolean handleKexCompressionMessage(Session session,
                                            Buffer buffer)
                                     throws Exception

Parses the SSH_MSG_NEWCOMPRESS message. Note: this method is called regardless of whether isKexExtensionsAvailable returns true for the session.

Parameters:

session - The Session through which the message was received

buffer - The message buffer

Returns:

true if message handled - if false then SSH_MSG_UNIMPLEMENTED will be generated

Throws:

Exception - If failed to handle the message

See Also:

RFC-8308 - section 3.2

handleKexExtensionRequest

default boolean handleKexExtensionRequest(Session session,
                                          int index,
                                          int count,
                                          String name,
                                          byte[] data)
                                   throws Exception

Invoked by handleKexExtensionsMessage(Session, Buffer) in order to handle a specific extension.

Parameters:

session - The Session through which the message was received

index - The 0-based extension index

count - The total extensions in the message

name - The extension name

data - The extension data

Returns:

true whether to proceed to the next extension or stop processing the rest

Throws:

Exception - If failed to handle the extension