org.apache.sshd.common.session.SessionContext Maven / Gradle / Ivy
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* distributed with this work for additional information
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* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
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* specific language governing permissions and limitations
* under the License.
*/
package org.apache.sshd.common.session;
import java.util.Map;
import org.apache.sshd.common.AttributeStore;
import org.apache.sshd.common.Closeable;
import org.apache.sshd.common.SshConstants;
import org.apache.sshd.common.auth.UsernameHolder;
import org.apache.sshd.common.cipher.BuiltinCiphers;
import org.apache.sshd.common.cipher.CipherInformation;
import org.apache.sshd.common.compression.CompressionInformation;
import org.apache.sshd.common.kex.KexProposalOption;
import org.apache.sshd.common.kex.KexState;
import org.apache.sshd.common.mac.MacInformation;
import org.apache.sshd.common.util.GenericUtils;
import org.apache.sshd.common.util.ValidateUtils;
import org.apache.sshd.common.util.net.ConnectionEndpointsIndicator;
/**
* A "succinct" summary of the most important attributes of an SSH session
*
* @author Apache MINA SSHD Project
*/
public interface SessionContext
extends ConnectionEndpointsIndicator,
UsernameHolder,
SessionHeartbeatController,
AttributeStore,
Closeable {
/**
* Default prefix expected for the client / server identification string
*
* @see RFC 4253 - section 4.2
*/
String DEFAULT_SSH_VERSION_PREFIX = "SSH-2.0-";
/**
* Backward compatible special prefix
*
* @see RFC 4253 - section 5
*/
String FALLBACK_SSH_VERSION_PREFIX = "SSH-1.99-";
/**
* Maximum number of characters for any single line sent as part of the initial handshake - according to
* RFC 4253 - section 4.2:
*
*
*
* The maximum length of the string is 255 characters,
* including the Carriage Return and Line Feed.
*
*
*/
int MAX_VERSION_LINE_LENGTH = 256;
/**
* @return A clone of the established session identifier - {@code null} if not yet established
*/
byte[] getSessionId();
/**
* Quick indication if this is a server or client session (instead of having to ask {@code instanceof}).
*
* @return {@code true} if this is a server session
*/
boolean isServerSession();
/**
* Retrieve the client version for this session.
*
* @return the client version - may be {@code null}/empty if versions not yet exchanged
*/
String getClientVersion();
/**
* @return An un-modifiable map of the latest KEX client proposal options May be empty if KEX not yet
* completed or re-keying in progress
* @see #getKexState()
*/
Map getClientKexProposals();
/**
* Retrieve the server version for this session.
*
* @return the server version - may be {@code null}/empty if versions not yet exchanged
*/
String getServerVersion();
/**
* @return An un-modifiable map of the latest KEX client proposal options. May be empty if KEX not yet
* completed or re-keying in progress
* @see #getKexState()
*/
Map getServerKexProposals();
KexState getKexState();
Map getKexNegotiationResult();
/**
* Retrieve one of the negotiated values during the KEX stage
*
* @param paramType The request {@link KexProposalOption} value - ignored if {@code null}
* @return The negotiated parameter value - {@code null} if invalid parameter or no negotiated value.
* @see #getKexState()
*/
String getNegotiatedKexParameter(KexProposalOption paramType);
/**
* Retrieves current cipher information - Note: may change if key re-exchange executed
*
* @param incoming If {@code true} then the cipher for the incoming data, otherwise for the outgoing data
* @return The {@link CipherInformation} - or {@code null} if not negotiated yet.
*/
CipherInformation getCipherInformation(boolean incoming);
/**
* Retrieves current compression information - Note: may change if key re-exchange executed
*
* @param incoming If {@code true} then the compression for the incoming data, otherwise for the outgoing data
* @return The {@link CompressionInformation} - or {@code null} if not negotiated yet.
*/
CompressionInformation getCompressionInformation(boolean incoming);
/**
* Retrieves current MAC information - Note: may change if key re-exchange executed
*
* @param incoming If {@code true} then the MAC for the incoming data, otherwise for the outgoing data
* @return The {@link MacInformation} - or {@code null} if not negotiated yet.
*/
MacInformation getMacInformation(boolean incoming);
/**
* @return {@code true} if session has successfully completed the authentication phase
*/
boolean isAuthenticated();
/**
* @param version The reported client/server version
* @return {@code true} if version not empty and starts with either {@value #DEFAULT_SSH_VERSION_PREFIX} or
* {@value #FALLBACK_SSH_VERSION_PREFIX}
*/
static boolean isValidVersionPrefix(String version) {
return GenericUtils.isNotEmpty(version)
&& (version.startsWith(DEFAULT_SSH_VERSION_PREFIX) || version.startsWith(FALLBACK_SSH_VERSION_PREFIX));
}
/**
* @param session The {@link SessionContext} to be examined
* @return {@code true} if the context is not {@code null} and the ciphers have been established to anything
* other than "none".
* @see #getNegotiatedKexParameter(KexProposalOption) getNegotiatedKexParameter
* @see KexProposalOption#CIPHER_PROPOSALS CIPHER_PROPOSALS
*/
static boolean isSecureSessionTransport(SessionContext session) {
if (session == null) {
return false;
}
for (KexProposalOption opt : KexProposalOption.CIPHER_PROPOSALS) {
String value = session.getNegotiatedKexParameter(opt);
if (GenericUtils.isEmpty(value)
|| BuiltinCiphers.Constants.NONE.equalsIgnoreCase(value)) {
return false;
}
}
return true;
}
/**
* @param session The {@link SessionContext} to be examined
* @return {@code true} if the context is not {@code null} and the MAC(s) used to verify packet integrity
* have been established.
* @see #getNegotiatedKexParameter(KexProposalOption) getNegotiatedKexParameter
* @see KexProposalOption#MAC_PROPOSALS MAC_PROPOSALS
*/
static boolean isDataIntegrityTransport(SessionContext session) {
if (session == null) {
return false;
}
for (KexProposalOption opt : KexProposalOption.MAC_PROPOSALS) {
String value = session.getNegotiatedKexParameter(opt);
if (GenericUtils.isEmpty(value)) {
return false;
}
}
return true;
}
static boolean isValidSessionPayloadSize(long value) {
return (value >= 0L) && (value < (Integer.MAX_VALUE - SshConstants.SSH_PACKET_HEADER_LEN - 8 /* some padding */));
}
static long validateSessionPayloadSize(long value, String format) {
ValidateUtils.checkTrue(isValidSessionPayloadSize(value), format, value);
return value;
}
}
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