org.apache.sshd.common.session.helpers.AbstractSession Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* 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
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.sshd.common.session.helpers;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.ProtocolException;
import java.net.SocketTimeoutException;
import java.nio.charset.StandardCharsets;
import java.security.GeneralSecurityException;
import java.time.Duration;
import java.time.Instant;
import java.util.AbstractMap.SimpleImmutableEntry;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Deque;
import java.util.EnumMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Objects;
import java.util.Set;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentLinkedDeque;
import java.util.concurrent.CopyOnWriteArraySet;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledFuture;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.TimeoutException;
import java.util.concurrent.atomic.AtomicLong;
import java.util.concurrent.atomic.AtomicReference;
import java.util.function.LongConsumer;
import java.util.logging.Level;
import java.util.stream.Collectors;
import org.apache.sshd.common.Closeable;
import org.apache.sshd.common.Factory;
import org.apache.sshd.common.FactoryManager;
import org.apache.sshd.common.NamedFactory;
import org.apache.sshd.common.NamedResource;
import org.apache.sshd.common.RuntimeSshException;
import org.apache.sshd.common.Service;
import org.apache.sshd.common.SshConstants;
import org.apache.sshd.common.SshException;
import org.apache.sshd.common.channel.ChannelListener;
import org.apache.sshd.common.cipher.Cipher;
import org.apache.sshd.common.cipher.CipherInformation;
import org.apache.sshd.common.compression.Compression;
import org.apache.sshd.common.compression.CompressionInformation;
import org.apache.sshd.common.digest.Digest;
import org.apache.sshd.common.forward.PortForwardingEventListener;
import org.apache.sshd.common.future.DefaultKeyExchangeFuture;
import org.apache.sshd.common.future.DefaultSshFuture;
import org.apache.sshd.common.future.GlobalRequestFuture;
import org.apache.sshd.common.future.KeyExchangeFuture;
import org.apache.sshd.common.global.GlobalRequestException;
import org.apache.sshd.common.io.IoSession;
import org.apache.sshd.common.io.IoWriteFuture;
import org.apache.sshd.common.kex.KexProposalOption;
import org.apache.sshd.common.kex.KexState;
import org.apache.sshd.common.kex.KeyExchange;
import org.apache.sshd.common.kex.KeyExchangeFactory;
import org.apache.sshd.common.kex.extension.KexExtensionHandler;
import org.apache.sshd.common.kex.extension.KexExtensionHandler.AvailabilityPhase;
import org.apache.sshd.common.kex.extension.KexExtensionHandler.KexPhase;
import org.apache.sshd.common.kex.extension.KexExtensions;
import org.apache.sshd.common.mac.Mac;
import org.apache.sshd.common.mac.MacInformation;
import org.apache.sshd.common.random.Random;
import org.apache.sshd.common.session.ReservedSessionMessagesHandler;
import org.apache.sshd.common.session.SessionDisconnectHandler;
import org.apache.sshd.common.session.SessionListener;
import org.apache.sshd.common.session.SessionWorkBuffer;
import org.apache.sshd.common.util.EventListenerUtils;
import org.apache.sshd.common.util.ExceptionUtils;
import org.apache.sshd.common.util.GenericUtils;
import org.apache.sshd.common.util.NumberUtils;
import org.apache.sshd.common.util.Readable;
import org.apache.sshd.common.util.ValidateUtils;
import org.apache.sshd.common.util.buffer.Buffer;
import org.apache.sshd.common.util.buffer.BufferUtils;
import org.apache.sshd.common.util.buffer.ByteArrayBuffer;
import org.apache.sshd.common.util.threads.ThreadUtils;
import org.apache.sshd.core.CoreModuleProperties;
/**
*
* The AbstractSession handles all the basic SSH protocol such as key exchange, authentication, encoding and decoding.
* Both server side and client side sessions should inherit from this abstract class. Some basic packet processing
* methods are defined but the actual call to these methods should be done from the {@link #handleMessage(Buffer)}
* method, which is dependent on the state and side of this session.
*
*
* TODO: if there is any very big packet, decoderBuffer and uncompressBuffer will get quite big and they won't be
* resized down at any time. Though the packet size is really limited by the channel max packet size
*
* @author Apache MINA SSHD Project
*/
@SuppressWarnings("checkstyle:MethodCount")
public abstract class AbstractSession extends SessionHelper {
/**
* Name of the property where this session is stored in the attributes of the underlying MINA session. See
* {@link #getSession(IoSession, boolean)} and {@link #attachSession(IoSession, AbstractSession)}.
*/
public static final String SESSION = "org.apache.sshd.session";
/**
* The pseudo random generator
*/
protected final Random random;
/**
* Session listeners container
*/
protected final Collection sessionListeners = new CopyOnWriteArraySet<>();
protected final SessionListener sessionListenerProxy;
/**
* Channel events listener container
*/
protected final Collection channelListeners = new CopyOnWriteArraySet<>();
protected final ChannelListener channelListenerProxy;
/**
* Port forwarding events listener container
*/
protected final Collection tunnelListeners = new CopyOnWriteArraySet<>();
protected final PortForwardingEventListener tunnelListenerProxy;
/*
* Key exchange support
*/
protected byte[] sessionId;
protected String serverVersion;
protected String clientVersion;
// if empty then means not-initialized
protected final Map serverProposal = new EnumMap<>(KexProposalOption.class);
protected final Map unmodServerProposal = Collections.unmodifiableMap(serverProposal);
protected final Map clientProposal = new EnumMap<>(KexProposalOption.class);
protected final Map unmodClientProposal = Collections.unmodifiableMap(clientProposal);
protected final Map negotiationResult = new EnumMap<>(KexProposalOption.class);
protected final Map unmodNegotiationResult = Collections.unmodifiableMap(negotiationResult);
protected KeyExchange kex;
protected Boolean firstKexPacketFollows;
protected boolean initialKexDone;
/**
* Holds the current key exchange state.
*/
protected final AtomicReference kexState = new AtomicReference<>(KexState.UNKNOWN);
protected final AtomicReference kexFutureHolder = new AtomicReference<>(null);
// The kexInitializedFuture is fulfilled when this side (client or server) has prepared its own proposal. Access is
// synchronized on kexState.
protected DefaultKeyExchangeFuture kexInitializedFuture;
/*
* SSH packets encoding / decoding support
*/
protected Cipher outCipher;
protected Cipher inCipher;
protected int outCipherSize = 8;
protected int inCipherSize = 8;
protected Mac outMac;
protected Mac inMac;
protected int outMacSize;
protected int inMacSize;
protected byte[] inMacResult;
protected Compression outCompression;
protected Compression inCompression;
/** Input packet sequence number. */
protected long seqi;
/** Output packet sequence number. */
protected long seqo;
protected SessionWorkBuffer uncompressBuffer;
protected final SessionWorkBuffer decoderBuffer;
protected int decoderState;
protected int decoderLength;
protected SshException discarding;
protected final Object encodeLock = new Object();
protected final Object decodeLock = new Object();
protected final Object requestLock = new Object();
/**
* "Strict KEX" is a mitigation for the "Terrapin attack". The KEX protocol is modified as follows:
*
* - During the initial (unencrypted) KEX, no extra messages not strictly necessary for KEX are allowed. The
* KEX_INIT message must be the first one after the version identification, and no IGNORE or DEBUG messages are
* allowed until the KEX is completed. If a party receives such a message, it terminates the connection.
* - Message sequence numbers are reset to zero after a key exchange (initial or later). When the NEW_KEYS message
* has been sent, the outgoing message number is reset; after a NEW_KEYS message has been received, the incoming
* message number is reset.
*
* Strict KEX is negotiated in the original KEX proposal; it is active if and only if both parties indicate that
* they support strict KEX.
*/
protected boolean strictKex;
protected long initialKexInitSequenceNumber = -1;
/**
* The {@link KeyExchangeMessageHandler} instance also serves as lock protecting {@link #kexState} changes from DONE
* to INIT or RUN, and from KEYS to DONE.
*/
protected final KeyExchangeMessageHandler kexHandler;
/*
* Rekeying
*/
protected final AtomicLong inPacketsCount = new AtomicLong(0L);
protected final AtomicLong outPacketsCount = new AtomicLong(0L);
protected final AtomicLong inBytesCount = new AtomicLong(0L);
protected final AtomicLong outBytesCount = new AtomicLong(0L);
protected final AtomicLong inBlocksCount = new AtomicLong(0L);
protected final AtomicLong outBlocksCount = new AtomicLong(0L);
protected final AtomicReference lastKeyTimeValue = new AtomicReference<>(Instant.now());
// we initialize them here in case super constructor calls some methods that use these values
protected long maxRekyPackets;
protected long maxRekeyBytes;
protected Duration maxRekeyInterval;
/**
* Resulting message coding settings at the end of a key exchange for incoming messages.
*
* @see #prepareNewKeys()
* @see #setInputEncoding()
*/
protected MessageCodingSettings inSettings;
/**
* Resulting message coding settings at the end of a key exchange for outgoing messages.
*
* @see #prepareNewKeys()
* @see #setOutputEncoding()
*/
protected MessageCodingSettings outSettings;
protected final CurrentService currentService;
// SSH_MSG_IGNORE stream padding
protected int ignorePacketDataLength;
protected long ignorePacketsFrequency;
protected int ignorePacketsVariance;
protected final AtomicLong maxRekeyBlocks
= new AtomicLong(CoreModuleProperties.REKEY_BYTES_LIMIT.getRequiredDefault() / 16);
protected final AtomicLong ignorePacketsCount
= new AtomicLong(CoreModuleProperties.IGNORE_MESSAGE_FREQUENCY.getRequiredDefault());
/**
* Used to wait for results of global requests sent with {@code want-reply = true}. Note that per RFC 4254, global
* requests may be sent at any time, but success/failure replies MUST come in the order the requests were sent. Some
* implementations may also reply with SSH_MSG_UNIMPLEMENTED, on which RFC 4253 says they must be sent in the order
* the message was received.
*
* This implies that it is legal to send "nested" global requests: a client or server may send two (or more) global
* requests, and then receives two (or more) replies in the correct order: first reply for the first request sent;
* second reply for the second request sent.
*
*
* We keep a FIFO list of pending global requests for which we expect a reply. We always add new global requests at
* the head. For success and failure replies, which don't identify the message sequence number of the global
* request, we apply the reply to the tail of the list. For unimplemented messages, we apply it to the request
* identified by the message sequence number, which normally also should be the tail.
*
*
* When a reply is received, the corresponding global request is removed from the list.
*
*
* Global requests sent with {@code want-reply = false} are never added to this list; they are fire-and-forget.
* According to the SSH RFCs, the peer MUST not reply on a message with {@code want-reply = false}. If it does so
* all the same, it is broken. We might then apply the result to the wrong pending global request if we have any.
*
*
* @see RFC 4254: Global Requests
* @see RFC 4254: Reserved Messages
* @see #request(Buffer, String, org.apache.sshd.common.future.GlobalRequestFuture.ReplyHandler)
* @see #requestSuccess(Buffer)
* @see #requestFailure(Buffer)
* @see #doInvokeUnimplementedMessageHandler(int, Buffer)
* @see #preClose()
*/
private final Deque pendingGlobalRequests = new ConcurrentLinkedDeque<>();
private final Map globalSequenceNumbers = new ConcurrentHashMap<>();
private byte[] clientKexData; // the payload of the client's SSH_MSG_KEXINIT
private byte[] serverKexData; // the payload of the server's SSH_MSG_KEXINIT
/**
* Create a new session.
*
* @param serverSession {@code true} if this is a server session, {@code false} if client one
* @param factoryManager the factory manager
* @param ioSession the underlying I/O session
*/
protected AbstractSession(boolean serverSession, FactoryManager factoryManager, IoSession ioSession) {
super(serverSession, factoryManager, ioSession);
this.decoderBuffer = new SessionWorkBuffer(this);
kexHandler = Objects.requireNonNull(initializeKeyExchangeMessageHandler(),
"No KeyExchangeMessageHandler set on the session");
currentService = Objects.requireNonNull(initializeCurrentService(), "No CurrentService set on the session");
attachSession(ioSession, this);
Factory factory = ValidateUtils.checkNotNull(
factoryManager.getRandomFactory(), "No random factory for %s", ioSession);
random = ValidateUtils.checkNotNull(
factory.create(), "No randomizer instance for %s", ioSession);
refreshConfiguration();
sessionListenerProxy = EventListenerUtils.proxyWrapper(
SessionListener.class, sessionListeners);
channelListenerProxy = EventListenerUtils.proxyWrapper(
ChannelListener.class, channelListeners);
tunnelListenerProxy = EventListenerUtils.proxyWrapper(
PortForwardingEventListener.class, tunnelListeners);
try {
signalSessionEstablished(ioSession);
} catch (RuntimeException e) {
throw e;
} catch (Exception e) {
throw new RuntimeSshException(e);
}
}
/**
* Creates a new {@link KeyExchangeMessageHandler} instance managing packet sending for this session.
*
* This initialization method is invoked once from the {@link AbstractSession} constructor. Do not rely on subclass
* fields being initialized.
*
*
* @return a new {@link KeyExchangeMessageHandler} instance for the session
*/
protected KeyExchangeMessageHandler initializeKeyExchangeMessageHandler() {
return new KeyExchangeMessageHandler(this, log);
}
/**
* Creates a new {@link CurrentService} instance managing this session's current SSH service.
*
* This initialization method is invoked once from the {@link AbstractSession} constructor. Do not rely on subclass
* fields being initialized.
*
*
* @return a new {@link CurrentService} instance for the session
*/
protected CurrentService initializeCurrentService() {
return new CurrentService(this);
}
/**
* @param len The packet payload size
* @param blockSize The cipher block size
* @param etmMode Whether using "encrypt-then-MAC" mode
* @return The required padding length
*/
public static int calculatePadLength(int len, int blockSize, boolean etmMode) {
/*
* Note: according to RFC-4253 section 6:
*
* The minimum size of a packet is 16 (or the cipher block size, whichever is larger) bytes (plus 'mac').
*
* Since all out ciphers, MAC(s), etc. have a block size > 8 then the minimum size of the packet will be at
* least 16 due to the padding at the very least - so even packets that contain an opcode with no arguments will
* be above this value. This avoids an un-necessary call to Math.max(len, 16) for each and every packet
*/
len++; // the pad length
if (!etmMode) {
len += Integer.BYTES;
}
/*
* Note: according to RFC-4253 section 6:
*
* Note that the length of the concatenation of 'packet_length', 'padding_length', 'payload', and 'random
* padding' MUST be a multiple of the cipher block size or 8, whichever is larger.
*
* However, we currently do not have ciphers with a block size of less than 8 so we do not take this into
* account in order to accelerate the calculation and avoiding an un-necessary call to Math.max(blockSize, 8)
* for each and every packet.
*/
int pad = (-len) & (blockSize - 1);
if (pad < blockSize) {
pad += blockSize;
}
return pad;
}
@Override
public String getServerVersion() {
return serverVersion;
}
@Override
public Map getServerKexProposals() {
return unmodServerProposal;
}
@Override
public String getClientVersion() {
return clientVersion;
}
@Override
public Map getClientKexProposals() {
return unmodClientProposal;
}
@Override
public KeyExchange getKex() {
return kex;
}
@Override
public KexState getKexState() {
return kexState.get();
}
@Override
public byte[] getSessionId() {
// return a clone to avoid anyone changing the internal value
return NumberUtils.isEmpty(sessionId) ? sessionId : sessionId.clone();
}
@Override
public Map getKexNegotiationResult() {
return unmodNegotiationResult;
}
@Override
public String getNegotiatedKexParameter(KexProposalOption paramType) {
if (paramType == null) {
return null;
}
synchronized (negotiationResult) {
return negotiationResult.get(paramType);
}
}
@Override
public CipherInformation getCipherInformation(boolean incoming) {
return incoming ? inCipher : outCipher;
}
@Override
public CompressionInformation getCompressionInformation(boolean incoming) {
return incoming ? inCompression : outCompression;
}
@Override
public MacInformation getMacInformation(boolean incoming) {
return incoming ? inMac : outMac;
}
/**
*
* Main input point for the MINA framework.
*
*
*
* This method will be called each time new data is received on the socket and will append it to the input buffer
* before calling the {@link #decode()} method.
*
*
* @param buffer the new buffer received
* @throws Exception if an error occurs while decoding or handling the data
*/
public void messageReceived(Readable buffer) throws Exception {
synchronized (decodeLock) {
decoderBuffer.putBuffer(buffer);
// One of those properties will be set by the constructor and the other
// one should be set by the readIdentification method
if ((clientVersion == null) || (serverVersion == null)) {
if (readIdentification(decoderBuffer)) {
decoderBuffer.compact();
} else {
return;
}
}
decode();
}
}
/**
* Refresh whatever internal configuration is not {@code final}
*/
protected void refreshConfiguration() {
synchronized (random) {
// re-keying configuration
maxRekeyBytes = CoreModuleProperties.REKEY_BYTES_LIMIT.getRequired(this);
maxRekeyInterval = CoreModuleProperties.REKEY_TIME_LIMIT.getRequired(this);
maxRekyPackets = CoreModuleProperties.REKEY_PACKETS_LIMIT.getRequired(this);
// intermittent SSH_MSG_IGNORE stream padding
ignorePacketDataLength = CoreModuleProperties.IGNORE_MESSAGE_SIZE.getRequired(this);
ignorePacketsFrequency = CoreModuleProperties.IGNORE_MESSAGE_FREQUENCY.getRequired(this);
ignorePacketsVariance = CoreModuleProperties.IGNORE_MESSAGE_VARIANCE.getRequired(this);
if (ignorePacketsVariance >= ignorePacketsFrequency) {
ignorePacketsVariance = 0;
}
long countValue = calculateNextIgnorePacketCount(
random, ignorePacketsFrequency, ignorePacketsVariance);
ignorePacketsCount.set(countValue);
}
}
/**
* Abstract method for processing incoming decoded packets. The given buffer will hold the decoded packet, starting
* from the command byte at the read position.
*
* @param buffer The {@link Buffer} containing the packet - it may be re-used to generate the response once
* request has been decoded
* @throws Exception if an exception occurs while handling this packet.
* @see #doHandleMessage(Buffer)
*/
protected void handleMessage(Buffer buffer) throws Exception {
try {
ThreadUtils.runAsInternal(() -> {
doHandleMessage(buffer);
return null;
});
} catch (Throwable e) {
DefaultKeyExchangeFuture kexFuture = kexFutureHolder.get();
// if have any ongoing KEX notify it about the failure
if (kexFuture != null) {
kexFuture.setValue(e);
}
if (e instanceof Exception) {
throw (Exception) e;
} else {
throw new RuntimeSshException(e);
}
}
}
protected void doHandleMessage(Buffer buffer) throws Exception {
int cmd = buffer.getUByte();
if (log.isDebugEnabled()) {
log.debug("doHandleMessage({}) process #{} {}", this, seqi - 1,
SshConstants.getCommandMessageName(cmd));
}
switch (cmd) {
case SshConstants.SSH_MSG_DISCONNECT:
handleDisconnect(buffer);
break;
case SshConstants.SSH_MSG_IGNORE:
failStrictKex(cmd);
handleIgnore(buffer);
break;
case SshConstants.SSH_MSG_UNIMPLEMENTED:
failStrictKex(cmd);
handleUnimplemented(buffer);
break;
case SshConstants.SSH_MSG_DEBUG:
// Fail after handling -- by default a message will be logged, which might be helpful.
handleDebug(buffer);
failStrictKex(cmd);
break;
case SshConstants.SSH_MSG_SERVICE_REQUEST:
failStrictKex(cmd);
handleServiceRequest(buffer);
break;
case SshConstants.SSH_MSG_SERVICE_ACCEPT:
failStrictKex(cmd);
handleServiceAccept(buffer);
break;
case SshConstants.SSH_MSG_KEXINIT:
handleKexInit(buffer);
break;
case SshConstants.SSH_MSG_NEWKEYS:
handleNewKeys(cmd, buffer);
break;
case KexExtensions.SSH_MSG_EXT_INFO:
failStrictKex(cmd);
handleKexExtension(cmd, buffer);
break;
case KexExtensions.SSH_MSG_NEWCOMPRESS:
failStrictKex(cmd);
handleNewCompression(cmd, buffer);
break;
default:
if ((cmd >= SshConstants.SSH_MSG_KEX_FIRST) && (cmd <= SshConstants.SSH_MSG_KEX_LAST)) {
if (firstKexPacketFollows != null) {
try {
if (!handleFirstKexPacketFollows(cmd, buffer, firstKexPacketFollows)) {
break;
}
} finally {
firstKexPacketFollows = null; // avoid re-checking
}
}
handleKexMessage(cmd, buffer);
} else {
failStrictKex(cmd);
if (currentService.process(cmd, buffer)) {
resetIdleTimeout();
} else {
/*
* According to https://tools.ietf.org/html/rfc4253#section-11.4
*
* An implementation MUST respond to all unrecognized messages with an SSH_MSG_UNIMPLEMENTED
* message in the order in which the messages were received.
*/
if (log.isDebugEnabled()) {
log.debug("process({}) Unsupported command: {}", this, SshConstants.getCommandMessageName(cmd));
}
notImplemented(cmd, buffer);
}
}
break;
}
checkRekey();
}
protected void failStrictKex(int cmd) throws SshException {
if (!initialKexDone && strictKex) {
throw new SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
SshConstants.getCommandMessageName(cmd) + " not allowed during initial key exchange in strict KEX");
}
}
protected boolean handleFirstKexPacketFollows(int cmd, Buffer buffer, boolean followFlag) {
if (!followFlag) {
return true; // if 1st KEX packet does not follow then process the command
}
/*
* According to RFC4253 section 7.1:
*
* If the other party's guess was wrong, and this field was TRUE, the next packet MUST be silently ignored
*/
boolean debugEnabled = log.isDebugEnabled();
for (KexProposalOption option : KexProposalOption.FIRST_KEX_PACKET_GUESS_MATCHES) {
Map.Entry result = comparePreferredKexProposalOption(option);
if (result != null) {
if (debugEnabled) {
log.debug(
"handleFirstKexPacketFollows({})[{}] 1st follow KEX packet {} option mismatch: client={}, server={}",
this, SshConstants.getCommandMessageName(cmd), option, result.getKey(), result.getValue());
}
return false;
}
}
return true;
}
/**
* Compares the specified {@link KexProposalOption} option value for client vs. server
*
* @param option The option to check
* @return {@code null} if option is equal, otherwise a key/value pair where key=client option value and
* value=the server-side one
*/
protected Map.Entry comparePreferredKexProposalOption(KexProposalOption option) {
String[] clientPreferences = GenericUtils.split(clientProposal.get(option), ',');
String clientValue = GenericUtils.isEmpty(clientPreferences) ? null : clientPreferences[0];
String[] serverPreferences = GenericUtils.split(serverProposal.get(option), ',');
String serverValue = GenericUtils.isEmpty(serverPreferences) ? null : serverPreferences[0];
if (GenericUtils.isEmpty(clientValue) || GenericUtils.isEmpty(serverValue)
|| (!Objects.equals(clientValue, serverValue))) {
return new SimpleImmutableEntry<>(clientValue, serverValue);
}
return null;
}
/**
* Send a message to put new keys into use.
*
* @return An {@link IoWriteFuture} that can be used to wait and check the result of sending the packet
* @throws Exception if an error occurs sending the message
*/
protected IoWriteFuture sendNewKeys() throws Exception {
if (log.isDebugEnabled()) {
log.debug("sendNewKeys({}) Send SSH_MSG_NEWKEYS", this);
}
prepareNewKeys();
Buffer buffer = createBuffer(SshConstants.SSH_MSG_NEWKEYS, Byte.SIZE);
IoWriteFuture future;
synchronized (encodeLock) {
// writePacket() would also work since it would never try to queue the packet, and would never try to
// initiate a new KEX, and thus would never try to get the kexLock monitor. If it did, we might get a
// deadlock due to lock inversion. It seems safer to push this out directly, though.
future = doWritePacket(buffer);
// Use the new settings from now on for any outgoing packet
setOutputEncoding();
}
kexHandler.updateState(() -> kexState.set(KexState.KEYS));
resetIdleTimeout();
/*
* According to https://tools.ietf.org/html/rfc8308#section-2.4:
*
*
* If a client sends SSH_MSG_EXT_INFO, it MUST send it as the next packet following the client's first
* SSH_MSG_NEWKEYS message to the server.
*
* If a server sends SSH_MSG_EXT_INFO, it MAY send it at zero, one, or both of the following opportunities:
*
* + As the next packet following the server's first SSH_MSG_NEWKEYS.
*/
KexExtensionHandler extHandler = getKexExtensionHandler();
if ((extHandler != null) && extHandler.isKexExtensionsAvailable(this, AvailabilityPhase.NEWKEYS)) {
extHandler.sendKexExtensions(this, KexPhase.NEWKEYS);
}
SimpleImmutableEntry flushDone = kexHandler.terminateKeyExchange();
// Flush the queue asynchronously.
int numPending = flushDone.getKey().intValue();
if (numPending == 0) {
if (log.isDebugEnabled()) {
log.debug("handleNewKeys({}) No pending packets to flush at end of KEX", this);
}
flushDone.getValue().setValue(Boolean.TRUE);
} else {
if (log.isDebugEnabled()) {
log.debug("handleNewKeys({}) {} pending packets to flush at end of KEX", this, numPending);
}
kexHandler.flushQueue(flushDone.getValue());
}
return future;
}
protected void handleKexMessage(int cmd, Buffer buffer) throws Exception {
validateKexState(cmd, KexState.RUN);
boolean debugEnabled = log.isDebugEnabled();
if (kex.next(cmd, buffer)) {
if (debugEnabled) {
log.debug("handleKexMessage({})[{}] KEX processing complete after cmd={}",
this, kex.getName(), cmd);
}
checkKeys();
sendNewKeys();
} else {
if (debugEnabled) {
log.debug("handleKexMessage({})[{}] more KEX packets expected after cmd={}",
this, kex.getName(), cmd);
}
}
}
protected void handleKexExtension(int cmd, Buffer buffer) throws Exception {
KexExtensionHandler extHandler = getKexExtensionHandler();
int startPos = buffer.rpos();
if ((extHandler != null) && extHandler.handleKexExtensionsMessage(this, buffer)) {
return;
}
buffer.rpos(startPos); // restore original read position
notImplemented(cmd, buffer);
}
protected void handleNewCompression(int cmd, Buffer buffer) throws Exception {
KexExtensionHandler extHandler = getKexExtensionHandler();
int startPos = buffer.rpos();
if ((extHandler != null) && extHandler.handleKexCompressionMessage(this, buffer)) {
return;
}
buffer.rpos(startPos); // restore original read position
notImplemented(cmd, buffer);
}
protected void handleServiceRequest(Buffer buffer) throws Exception {
String serviceName = buffer.getString();
handleServiceRequest(serviceName, buffer);
}
protected boolean handleServiceRequest(String serviceName, Buffer buffer) throws Exception {
boolean debugEnabled = log.isDebugEnabled();
if (debugEnabled) {
log.debug("handleServiceRequest({}) SSH_MSG_SERVICE_REQUEST '{}'", this, serviceName);
}
KexState state = kexState.get();
if (!validateServiceKexState(state)) {
throw new IllegalStateException(
"Received " + SshConstants.getCommandMessageName(SshConstants.SSH_MSG_SERVICE_REQUEST)
+ " while in KEX state=" + state);
}
try {
startService(serviceName, buffer);
} catch (Throwable e) {
debug("handleServiceRequest({}) Service {} rejected: {} = {}",
this, serviceName, e.getClass().getSimpleName(), e.getMessage(), e);
disconnect(SshConstants.SSH2_DISCONNECT_SERVICE_NOT_AVAILABLE, "Bad service request: " + serviceName);
return false;
}
if (debugEnabled) {
log.debug("handleServiceRequest({}) Accepted service {}", this, serviceName);
}
Buffer response = createBuffer(
SshConstants.SSH_MSG_SERVICE_ACCEPT, Byte.SIZE + GenericUtils.length(serviceName));
response.putString(serviceName);
writePacket(response);
return true;
}
protected boolean validateServiceKexState(KexState state) {
if (KexState.DONE.equals(state)) {
return true;
} else if (KexState.INIT.equals(state)) {
// Allow service requests that were "in flight" when we sent our own KEX_INIT. We will send back the accept
// only after KEX is done. However, we will refuse a service request before the initial KEX.
return initialKexDone;
}
return false;
}
protected void handleServiceAccept(Buffer buffer) throws Exception {
handleServiceAccept(buffer.getString(), buffer);
}
protected void handleServiceAccept(String serviceName, Buffer buffer) throws Exception {
if (log.isDebugEnabled()) {
log.debug("handleServiceAccept({}) SSH_MSG_SERVICE_ACCEPT service={}", this, serviceName);
}
KexState state = kexState.get();
if (!validateServiceKexState(state)) {
throw new IllegalStateException(
"Received " + SshConstants.getCommandMessageName(SshConstants.SSH_MSG_SERVICE_REQUEST)
+ " while in KEX state=" + state);
}
}
protected void handleKexInit(Buffer buffer) throws Exception {
if (log.isDebugEnabled()) {
log.debug("handleKexInit({}) SSH_MSG_KEXINIT", this);
}
receiveKexInit(buffer);
doKexNegotiation();
}
private enum KexStart {
PEER,
BOTH,
ONGOING
}
protected void doKexNegotiation() throws Exception {
KexStart starting = kexHandler.updateState(() -> {
if (kexState.compareAndSet(KexState.DONE, KexState.RUN)) {
kexHandler.initNewKeyExchange();
return KexStart.PEER;
} else if (kexState.compareAndSet(KexState.INIT, KexState.RUN)) {
return KexStart.BOTH;
}
return KexStart.ONGOING;
});
switch (starting) {
case PEER:
sendKexInit();
break;
case BOTH:
DefaultKeyExchangeFuture initFuture;
synchronized (kexState) {
initFuture = kexInitializedFuture;
if (initFuture == null) {
initFuture = new DefaultKeyExchangeFuture(toString(), null);
kexInitializedFuture = initFuture;
}
}
// requestNewKeyExchange() is running in some other thread: wait until it has set up our own proposal.
// The timeout is a last resort only to avoid blocking indefinitely in case something goes
// catastrophically wrong somewhere; it should never be hit. If it is, an exception will be thrown.
//
// See https://issues.apache.org/jira/browse/SSHD-1197
initFuture.await(CoreModuleProperties.KEX_PROPOSAL_SETUP_TIMEOUT.getRequired(this));
break;
default:
throw new IllegalStateException("Received SSH_MSG_KEXINIT while key exchange is running");
}
Map result = negotiate();
String kexAlgorithm = result.get(KexProposalOption.ALGORITHMS);
Collection kexFactories = getKeyExchangeFactories();
KeyExchangeFactory kexFactory = NamedResource.findByName(
kexAlgorithm, String.CASE_INSENSITIVE_ORDER, kexFactories);
ValidateUtils.checkNotNull(kexFactory, "Unknown negotiated KEX algorithm: %s", kexAlgorithm);
byte[] v_s = serverVersion.getBytes(StandardCharsets.UTF_8);
byte[] v_c = clientVersion.getBytes(StandardCharsets.UTF_8);
byte[] i_s;
byte[] i_c;
synchronized (kexState) {
i_s = getServerKexData();
i_c = getClientKexData();
}
kex = kexFactory.createKeyExchange(this);
kex.init(v_s, v_c, i_s, i_c);
synchronized (kexState) {
kexInitializedFuture = null;
}
signalSessionEvent(SessionListener.Event.KexCompleted);
}
protected void handleNewKeys(int cmd, Buffer buffer) throws Exception {
boolean debugEnabled = log.isDebugEnabled();
if (debugEnabled) {
log.debug("handleNewKeys({}) SSH_MSG_NEWKEYS command={}",
this, SshConstants.getCommandMessageName(cmd));
}
validateKexState(cmd, KexState.KEYS);
// It is guaranteed that we handle the peer's SSH_MSG_NEWKEYS after having sent our own.
// prepareNewKeys() was already called in sendNewKeys().
//
// From now on, use the new settings for any incoming message.
setInputEncoding();
synchronized (kexState) {
kexInitializedFuture = null;
}
initialKexDone = true;
DefaultKeyExchangeFuture kexFuture = kexFutureHolder.get();
if (kexFuture != null) {
kexFuture.setValue(Boolean.TRUE);
}
signalSessionEvent(SessionListener.Event.KeyEstablished);
kexHandler.updateState(() -> {
kex = null; // discard and GC since KEX is completed
kexState.set(KexState.DONE);
});
synchronized (futureLock) {
futureLock.notifyAll();
}
}
protected void validateKexState(int cmd, KexState expected) {
KexState actual = kexState.get();
if (!expected.equals(actual)) {
throw new IllegalStateException("Received KEX command=" + SshConstants.getCommandMessageName(cmd)
+ " while in state=" + actual + " instead of " + expected);
}
}
@Override
protected Closeable getInnerCloseable() {
Closeable closer = builder()
.parallel(toString(), getServices())
.close(getIoSession())
.build();
closer.addCloseFutureListener(future -> clearAttributes());
return closer;
}
@Override
protected void preClose() {
DefaultKeyExchangeFuture initFuture;
synchronized (kexState) {
initFuture = kexInitializedFuture;
}
if (initFuture != null) {
initFuture.setValue(new SshException("Session closing while KEX in progress"));
}
DefaultKeyExchangeFuture kexFuture = kexFutureHolder.get();
if (kexFuture != null) {
// if have any pending KEX then notify it about the closing session
kexFuture.setValue(new SshException("Session closing while KEX in progress"));
}
kexHandler.shutdown();
// if anyone waiting for global response notify them about the closing session
boolean debugEnabled = log.isDebugEnabled();
for (;;) {
GlobalRequestFuture future = pendingGlobalRequests.pollLast();
if (future == null) {
break;
}
if (debugEnabled) {
log.debug("preClose({}): Session closing; failing still pending global request {}", this, future.getId());
}
future.setValue(new SshException("Session is closing"));
}
// Fire 'close' event
try {
signalSessionClosed();
} finally {
// clear the listeners since we are closing the session (quicker GC)
this.sessionListeners.clear();
this.channelListeners.clear();
this.tunnelListeners.clear();
}
super.preClose();
}
protected List getServices() {
Service service = currentService.getService();
return (service != null)
? Collections.singletonList(service)
: Collections.emptyList();
}
@Override
public T getService(Class clazz) {
Collection registeredServices = getServices();
ValidateUtils.checkState(GenericUtils.isNotEmpty(registeredServices),
"No registered services to look for %s", clazz.getSimpleName());
for (Service s : registeredServices) {
if (clazz.isInstance(s)) {
return clazz.cast(s);
}
}
throw new IllegalStateException("Attempted to access unknown service " + clazz.getSimpleName());
}
@Override
protected Buffer preProcessEncodeBuffer(int cmd, Buffer buffer) throws IOException {
buffer = super.preProcessEncodeBuffer(cmd, buffer);
// SSHD-968 - remember global request outgoing sequence number
LongConsumer setter = globalSequenceNumbers.remove(buffer);
if (setter != null) {
setter.accept(seqo);
}
return buffer;
}
@Override
public IoWriteFuture writePacket(Buffer buffer) throws IOException {
return kexHandler.writePacket(buffer, 0, null);
}
@Override
public IoWriteFuture writePacket(Buffer buffer, long timeout, TimeUnit unit) throws IOException {
long timeoutMillis = unit.toMillis(timeout);
IoWriteFuture writeFuture;
try {
long start = System.currentTimeMillis();
writeFuture = kexHandler.writePacket(buffer, timeout, unit);
long elapsed = System.currentTimeMillis() - start;
if (elapsed >= timeoutMillis) {
// We just barely made it. Give it a tiny grace period.
timeoutMillis = 1;
} else {
timeoutMillis -= elapsed;
}
} catch (InterruptedIOException e) {
// Already timed out
PendingWriteFuture timedOut = new PendingWriteFuture(this, buffer);
Throwable t = new TimeoutException("Timeout writing packet: " + timeout + " " + unit);
t.initCause(e);
if (log.isDebugEnabled()) {
log.debug("writePacket({}): {}", AbstractSession.this, t.getMessage());
}
timedOut.setValue(t);
return timedOut;
}
if (writeFuture.isDone()) {
// No need to schedule anything.
return writeFuture;
}
@SuppressWarnings("unchecked")
DefaultSshFuture future = (DefaultSshFuture) writeFuture;
FactoryManager factoryManager = getFactoryManager();
ScheduledExecutorService executor = factoryManager.getScheduledExecutorService();
ScheduledFuture sched = executor.schedule(() -> {
Throwable t = new TimeoutException("Timeout writing packet: " + timeout + " " + unit);
if (log.isDebugEnabled()) {
log.debug("writePacket({}): {}", AbstractSession.this, t.getMessage());
}
future.setValue(t);
}, timeoutMillis, TimeUnit.MILLISECONDS);
future.addListener(f -> sched.cancel(false));
return writeFuture;
}
// NOTE: must acquire encodeLock when calling this method
protected Buffer resolveOutputPacket(Buffer buffer) throws IOException {
Buffer ignoreBuf = null;
int ignoreDataLen = resolveIgnoreBufferDataLength();
if (ignoreDataLen > 0) {
ignoreBuf = createBuffer(SshConstants.SSH_MSG_IGNORE, ignoreDataLen + Byte.SIZE);
ignoreBuf.putUInt(ignoreDataLen);
int wpos = ignoreBuf.wpos();
synchronized (random) {
random.fill(ignoreBuf.array(), wpos, ignoreDataLen);
}
ignoreBuf.wpos(wpos + ignoreDataLen);
if (log.isDebugEnabled()) {
log.debug("resolveOutputPacket({}) append SSH_MSG_IGNORE message", this);
}
}
int curPos = buffer.rpos();
byte[] data = buffer.array();
int cmd = data[curPos] & 0xFF; // usually the 1st byte is the command
buffer = validateTargetBuffer(cmd, buffer);
if (ignoreBuf != null) {
ignoreBuf = encode(ignoreBuf);
IoSession networkSession = getIoSession();
networkSession.writeBuffer(ignoreBuf);
}
return encode(buffer);
}
protected IoWriteFuture doWritePacket(Buffer buffer) throws IOException {
// Synchronize all write requests as needed by the encoding algorithm
// and also queue the write request in this synchronized block to ensure
// packets are sent in the correct order
synchronized (encodeLock) {
Buffer packet = resolveOutputPacket(buffer);
IoSession networkSession = getIoSession();
IoWriteFuture future = networkSession.writeBuffer(packet);
return future;
}
}
protected int resolveIgnoreBufferDataLength() {
if (!initialKexDone || (ignorePacketDataLength <= 0)
|| (ignorePacketsFrequency <= 0L)
|| (ignorePacketsVariance < 0)) {
return 0;
}
long count = ignorePacketsCount.decrementAndGet();
if (count > 0L) {
return 0;
}
synchronized (random) {
count = calculateNextIgnorePacketCount(
random, ignorePacketsFrequency, ignorePacketsVariance);
ignorePacketsCount.set(count);
return ignorePacketDataLength + random.random(ignorePacketDataLength);
}
}
private boolean wantReply(Buffer buffer) {
// Examine the buffer to get the want-reply flag
int rpos = buffer.rpos();
buffer.getByte(); // Skip command
buffer.getString(); // Skip request name
boolean replyFlag = buffer.getBoolean();
buffer.rpos(rpos); // reset buffer
return replyFlag;
}
@Override
public Buffer request(String request, Buffer buffer, long maxWaitMillis) throws IOException {
ValidateUtils.checkTrue(maxWaitMillis > 0,
"Requested timeout for " + request + " is not strictly greater than zero: " + maxWaitMillis);
boolean debugEnabled = log.isDebugEnabled();
boolean withReply = wantReply(buffer);
GlobalRequestFuture future = request(buffer, request, null);
Object result;
boolean done = false;
try {
if (debugEnabled) {
log.debug("request({}) request={}, timeout={}ms", this, request, maxWaitMillis);
}
done = future.await(maxWaitMillis);
result = future.getValue();
} catch (InterruptedIOException e) {
throw (InterruptedIOException) new InterruptedIOException(
"Interrupted while waiting for request=" + request + " result").initCause(e);
}
if (!isOpen()) {
throw new IOException("Session was closed or closing while awaiting reply for request=" + request);
}
if (withReply) {
if (debugEnabled) {
log.debug("request({}) request={}, timeout={}ms, requestSeqNo={}, done {}, result received={}", this, request,
maxWaitMillis, future.getSequenceNumber(), done, result instanceof Buffer);
}
if (!done || result == null) {
throw new SocketTimeoutException("No response received after " + maxWaitMillis + "ms for request=" + request);
}
// The operation is specified to return null if the request could be made, but got an error reply.
// The caller cannot distinguish between SSH_MSG_UNIMPLEMENTED and SSH_MSG_REQUEST_FAILURE.
if (result instanceof GlobalRequestException) {
if (debugEnabled) {
log.debug("request({}) request={}, requestSeqNo={}: received={}", this, request, future.getSequenceNumber(),
SshConstants.getCommandMessageName(((GlobalRequestException) result).getCode()));
}
return null;
}
}
if (result instanceof Throwable) {
throw new IOException("Exception on request " + request, (Throwable) result);
}
if (result instanceof Buffer) {
return (Buffer) result;
}
return null;
}
@Override
public GlobalRequestFuture request(Buffer buffer, String request, GlobalRequestFuture.ReplyHandler replyHandler)
throws IOException {
GlobalRequestFuture globalRequest;
if (!wantReply(buffer)) {
if (!isOpen()) {
throw new IOException("Global request " + request + ": session is closing or closed.");
}
// Fire-and-forget global requests (want-reply = false) are always allowed; we don't need to register the
// future, nor do we have to wait for anything. Client code can wait on the returned future if it wants to
// be sure the message has been sent.
globalRequest = new GlobalRequestFuture(request, replyHandler) {
@Override
public void operationComplete(IoWriteFuture future) {
if (future.isWritten()) {
if (log.isDebugEnabled()) {
log.debug("makeGlobalRequest({})[{}] want-reply=false sent", this, getId());
}
setValue(new ByteArrayBuffer(new byte[0]));
GlobalRequestFuture.ReplyHandler handler = getHandler();
if (handler != null) {
handler.accept(SshConstants.SSH_MSG_REQUEST_SUCCESS, getBuffer());
}
}
super.operationComplete(future);
}
};
writePacket(buffer).addListener(globalRequest);
return globalRequest;
}
// We do expect a reply. The packet may get queued or otherwise delayed for an unknown time. We must
// consider this request pending only once its sequence number is known. If sending the message fails,
// the writeFuture will set an exception on the globalRequest, or will fail it.
globalRequest = new GlobalRequestFuture(request, replyHandler) {
@Override
public void operationComplete(IoWriteFuture future) {
if (!future.isWritten()) {
// If it was not written after all, make sure it's not considered pending anymore.
pendingGlobalRequests.removeFirstOccurrence(this);
}
// Super call will fulfill the future if not written
super.operationComplete(future);
if (future.isWritten() && getHandler() != null) {
// Fulfill this future now. The GlobalRequestFuture can thus be used to wait for the
// successful sending of the request, the framework will invoke the handler whenever
// the reply arrives. The buffer cannot be obtained though the future.
setValue(null);
}
}
};
if (!isOpen()) {
throw new IOException("Global request " + request + ": session is closing or closed.");
}
// This consumer will be invoked once before the packet actually goes out. Some servers respond to global
// requests with SSH_MSG_UNIMPLEMENTED instead of SSH_MSG_REQUEST_FAILURE (see SSHD-968), so we need to make
// sure we do know the sequence number.
globalSequenceNumbers.put(buffer, seqNo -> {
globalRequest.setSequenceNumber(seqNo);
if (log.isDebugEnabled()) {
log.debug("makeGlobalRequest({})[{}] want-reply=true with seqNo={}", this, globalRequest.getId(), seqNo);
}
// Insert at front
pendingGlobalRequests.push(globalRequest);
});
writePacket(buffer).addListener(f -> {
Throwable t = f.getException();
if (t != null) {
// Just in case we get an exception before preProcessEncodeBuffer was even called
globalSequenceNumbers.remove(buffer);
}
}).addListener(globalRequest); // Report errors through globalRequest, fulfilling globalRequest
return globalRequest;
}
@Override
protected boolean doInvokeUnimplementedMessageHandler(int cmd, Buffer buffer) throws Exception {
/*
* SSHD-968 Some servers respond to global requests with SSH_MSG_UNIMPLEMENTED instead of
* SSH_MSG_REQUEST_FAILURE (as mandated by https://tools.ietf.org/html/rfc4254#section-4) so deal with it.
*/
if (!pendingGlobalRequests.isEmpty() && cmd == SshConstants.SSH_MSG_UNIMPLEMENTED) {
// We do have ongoing global requests.
long msgSeqNo = buffer.rawUInt(buffer.rpos());
// Find the global request this applies to
GlobalRequestFuture future = pendingGlobalRequests.stream().filter(f -> f.getSequenceNumber() == msgSeqNo).findAny()
.orElse(null);
if (future != null && pendingGlobalRequests.removeFirstOccurrence(future)) {
// This SSH_MSG_UNIMPLEMENTED was the reply to a global request.
if (log.isDebugEnabled()) {
log.debug("doInvokeUnimplementedMessageHandler({}) report global request={} failure for seqNo={}", this,
future.getId(), msgSeqNo);
}
GlobalRequestFuture.ReplyHandler handler = future.getHandler();
if (handler != null) {
Buffer resultBuf = ByteArrayBuffer.getCompactClone(buffer.array(), buffer.rpos(), buffer.available());
handler.accept(cmd, resultBuf);
} else {
future.setValue(new GlobalRequestException(cmd));
}
return true; // message handled internally
} else if (future != null) {
// The SSH_MSG_UNIMPLEMENTED was for a global request, but that request is no longer in the list: it
// got terminated otherwise.
return true;
}
if (log.isTraceEnabled()) {
log.trace(
"doInvokeUnimplementedMessageHandler({}) SSH_MSG_UNIMPLEMENTED with message seqNo={} not for a global request",
this, msgSeqNo);
}
}
return super.doInvokeUnimplementedMessageHandler(cmd, buffer);
}
@Override
public Buffer createBuffer(byte cmd, int len) {
if (len <= 0) {
return prepareBuffer(cmd, new ByteArrayBuffer());
}
// Since the caller claims to know how many bytes they will need
// increase their request to account for our headers/footers if
// they actually send exactly this amount.
boolean etmMode = outMac != null && outMac.isEncryptThenMac();
int authLen = outCipher != null ? outCipher.getAuthenticationTagSize() : 0;
boolean authMode = authLen > 0;
int pad = calculatePadLength(len, outCipherSize, etmMode || authMode);
len += SshConstants.SSH_PACKET_HEADER_LEN + pad + authLen;
if (outMac != null) {
len += outMacSize;
}
return prepareBuffer(cmd, new ByteArrayBuffer(new byte[len + Byte.SIZE], false));
}
@Override
public Buffer prepareBuffer(byte cmd, Buffer buffer) {
buffer = validateTargetBuffer(cmd & 0xFF, buffer);
buffer.rpos(SshConstants.SSH_PACKET_HEADER_LEN);
buffer.wpos(SshConstants.SSH_PACKET_HEADER_LEN);
buffer.putByte(cmd);
return buffer;
}
/**
* Makes sure that the buffer used for output is not {@code null} or one of the session's internal ones used for
* decoding and uncompressing
*
* @param The {@link Buffer} type being validated
* @param cmd The most likely command this buffer refers to (not guaranteed to be correct)
* @param buffer The buffer to be examined
* @return The validated target instance - default same as input
* @throws IllegalArgumentException if any of the conditions is violated
*/
protected B validateTargetBuffer(int cmd, B buffer) {
ValidateUtils.checkNotNull(buffer, "No target buffer to examine for command=%d", cmd);
ValidateUtils.checkTrue(
buffer != decoderBuffer, "Not allowed to use the internal decoder buffer for command=%d", cmd);
ValidateUtils.checkTrue(
buffer != uncompressBuffer, "Not allowed to use the internal uncompress buffer for command=%d", cmd);
return buffer;
}
/**
* Encode a buffer into the SSH protocol. Note: This method must be called inside a {@code synchronized}
* block using {@code encodeLock}.
*
* @param buffer the buffer to encode
* @return The encoded buffer - may be different than original if input buffer does not have enough room
* for {@link SshConstants#SSH_PACKET_HEADER_LEN}, in which case a substitute buffer will be
* created and used.
* @throws IOException if an exception occurs during the encoding process
*/
protected Buffer encode(Buffer buffer) throws IOException {
try {
// Check that the packet has some free space for the header
int curPos = buffer.rpos();
int cmd = buffer.rawByte(curPos) & 0xFF; // usually the 1st byte is an SSH opcode
Buffer nb = preProcessEncodeBuffer(cmd, buffer);
if (nb != buffer) {
buffer = nb;
curPos = buffer.rpos();
int newCmd = buffer.rawByte(curPos) & 0xFF;
if (cmd != newCmd) {
log.warn("encode({}) - command changed from {}[{}] to {}[{}] by pre-processor",
this, cmd, SshConstants.getCommandMessageName(cmd),
newCmd, SshConstants.getCommandMessageName(newCmd));
cmd = newCmd;
}
}
// Grab the length of the packet (excluding the 5 header bytes)
int len = buffer.available();
if (log.isDebugEnabled()) {
log.debug("encode({}) packet #{} sending command={}[{}] len={}",
this, seqo, cmd, SshConstants.getCommandMessageName(cmd), len);
}
int off = curPos - SshConstants.SSH_PACKET_HEADER_LEN;
// Debug log the packet
boolean traceEnabled = log.isTraceEnabled();
if (traceEnabled) {
buffer.dumpHex(getSimplifiedLogger(), Level.FINEST,
"encode(" + this + ") packet #" + seqo, this);
}
// Compress the packet if needed
if ((outCompression != null)
&& outCompression.isCompressionExecuted()
&& (isAuthenticated() || (!outCompression.isDelayed()))) {
int oldLen = len;
outCompression.compress(buffer);
len = buffer.available();
if (traceEnabled) {
log.trace("encode({}) packet #{} command={}[{}] compressed {} -> {}",
this, seqo, cmd, SshConstants.getCommandMessageName(cmd), oldLen, len);
}
}
// Compute padding length
boolean etmMode = outMac != null && outMac.isEncryptThenMac();
int authSize = outCipher != null ? outCipher.getAuthenticationTagSize() : 0;
boolean authMode = authSize > 0;
int oldLen = len;
int pad = calculatePadLength(len, outCipherSize, etmMode || authMode);
len += Byte.BYTES + pad;
if (traceEnabled) {
log.trace("encode({}) packet #{} command={}[{}] len={}, pad={}, mac={}",
this, seqo, cmd, SshConstants.getCommandMessageName(cmd), len, pad, outMac);
}
// Write 5 header bytes
buffer.wpos(off);
buffer.putUInt(len);
buffer.putByte((byte) pad);
// Make sure enough room for padding and then fill it
buffer.wpos(off + oldLen + SshConstants.SSH_PACKET_HEADER_LEN + pad);
synchronized (random) {
random.fill(buffer.array(), buffer.wpos() - pad, pad);
}
if (authMode) {
int wpos = buffer.wpos();
buffer.wpos(wpos + authSize);
aeadOutgoingBuffer(buffer, off, len);
} else if (etmMode) {
// Do not encrypt the length field
encryptOutgoingBuffer(buffer, off + Integer.BYTES, len);
appendOutgoingMac(buffer, off, len);
} else {
appendOutgoingMac(buffer, off, len);
encryptOutgoingBuffer(buffer, off, len + Integer.BYTES);
}
// Increment packet id
seqo = (seqo + 1L) & 0x0ffffffffL;
// Update counters used to track re-keying
outPacketsCount.incrementAndGet();
outBytesCount.addAndGet(len);
// Make buffer ready to be read
buffer.rpos(off);
return buffer;
} catch (IOException e) {
throw e;
} catch (Exception e) {
throw new SshException(e);
}
}
protected void aeadOutgoingBuffer(Buffer buf, int offset, int len) throws Exception {
if (outCipher == null || outCipher.getAuthenticationTagSize() == 0) {
throw new IllegalArgumentException("AEAD mode requires an AEAD cipher");
}
byte[] data = buf.array();
outCipher.updateWithAAD(data, offset, Integer.BYTES, len);
int blocksCount = len / outCipherSize;
outBlocksCount.addAndGet(Math.max(1, blocksCount));
}
protected void appendOutgoingMac(Buffer buf, int offset, int len) throws Exception {
if (outMac == null) {
return;
}
int l = buf.wpos();
// ensure enough room for MAC in outgoing buffer
buf.wpos(l + outMacSize);
// Include sequence number
outMac.updateUInt(seqo);
// Include the length field in the MAC calculation
outMac.update(buf.array(), offset, len + Integer.BYTES);
// Append MAC to end of packet
outMac.doFinal(buf.array(), l);
}
protected void encryptOutgoingBuffer(Buffer buf, int offset, int len) throws Exception {
if (outCipher == null) {
return;
}
outCipher.update(buf.array(), offset, len);
int blocksCount = len / outCipherSize;
outBlocksCount.addAndGet(Math.max(1, blocksCount));
}
/**
* Decode the incoming buffer and handle packets as needed.
*
* @throws Exception If failed to decode
*/
protected void decode() throws Exception {
// Decoding loop
for (;;) {
int authSize = inCipher != null ? inCipher.getAuthenticationTagSize() : 0;
boolean authMode = authSize > 0;
int macSize = inMac != null ? inMacSize : 0;
boolean etmMode = inMac != null && inMac.isEncryptThenMac();
// Wait for beginning of packet
if (decoderState == 0) {
// The read position should always be 0 at this point because we have compacted this buffer
assert decoderBuffer.rpos() == 0;
/*
* Note: according to RFC-4253 section 6:
*
* Implementations SHOULD decrypt the length after receiving the first 8 (or cipher block size whichever
* is larger) bytes
*
* However, we currently do not have ciphers with a block size of less than 8 we avoid un-necessary
* Math.max(minBufLen, 8) for each and every packet
*/
int minBufLen = etmMode || authMode ? Integer.BYTES : inCipherSize;
// If we have received enough bytes, start processing those
if (decoderBuffer.available() > minBufLen) {
if (authMode) {
// RFC 5647: packet length encoded in additional data
inCipher.updateAAD(decoderBuffer.array(), 0, Integer.BYTES);
} else if ((inCipher != null) && (!etmMode)) {
// Decrypt the first bytes so we can extract the packet length
inCipher.update(decoderBuffer.array(), 0, inCipherSize);
inBlocksCount.incrementAndGet();
}
// Read packet length
decoderLength = decoderBuffer.getInt();
/*
* Check packet length validity - we allow 8 times the minimum required packet length support in
* order to be aligned with some OpenSSH versions that allow up to 256k
*/
boolean lengthOK = true;
if ((decoderLength < SshConstants.SSH_PACKET_HEADER_LEN)
|| (decoderLength > (8 * SshConstants.SSH_REQUIRED_PAYLOAD_PACKET_LENGTH_SUPPORT))) {
log.warn("decode({}) Error decoding packet(invalid length): {}", this, decoderLength);
lengthOK = false;
} else if (inCipher != null
&& ((decoderLength + ((authMode || etmMode) ? 0 : Integer.BYTES)) % inCipherSize != 0)) {
log.warn("decode({}) Error decoding packet(padding; not multiple of {}): {}", this, inCipherSize,
decoderLength);
lengthOK = false;
}
if (!lengthOK) {
decoderBuffer.dumpHex(getSimplifiedLogger(), Level.FINEST,
"decode(" + this + ") invalid length packet", this);
// Mitigation against CVE-2008-5161 AKA CPNI-957037: make any disconnections due to decoding
// errors indistinguishable from failed MAC checks.
//
// If we disconnect here, a client may still deduce (since it sent only one block) that the
// length check failed. So we keep on requesting more data and fail later. OpenSSH actually
// discards the next 256kB of data, but in fact any number of bytes will do.
//
// Remember the exception, continue requiring an arbitrary number of bytes, and throw the
// exception later.
discarding = new SshException(SshConstants.SSH2_DISCONNECT_PROTOCOL_ERROR,
"Invalid packet length: " + decoderLength);
decoderLength = decoderBuffer.available() + (2 + random.random(20)) * inCipherSize;
// Next larger multiple of the block size
decoderLength = ((decoderLength + (inCipherSize - 1)) / inCipherSize) * inCipherSize;
if (!authMode && !etmMode) {
decoderLength -= Integer.BYTES;
}
log.warn("decode({}) Invalid packet length; requesting {} bytes before disconnecting", this,
decoderLength - decoderBuffer.available());
}
// Ok, that's good, we can go to the next step
decoderState = 1;
} else {
// need more data
break;
}
// We have received the beginning of the packet
} else if (decoderState == 1) {
// The read position should always be after reading the packet length at this point
assert decoderBuffer.rpos() == Integer.BYTES;
// Check if the packet has been fully received
if (decoderBuffer.available() >= (decoderLength + macSize + authSize)) {
byte[] data = decoderBuffer.array();
if (authMode) {
inCipher.update(data, Integer.BYTES /* packet length is handled by AAD */, decoderLength);
int blocksCount = decoderLength / inCipherSize;
inBlocksCount.addAndGet(Math.max(1, blocksCount));
} else if (etmMode) {
validateIncomingMac(data, 0, decoderLength + Integer.BYTES);
if (inCipher != null) {
inCipher.update(data, Integer.BYTES /* packet length is unencrypted */, decoderLength);
int blocksCount = decoderLength / inCipherSize;
inBlocksCount.addAndGet(Math.max(1, blocksCount));
}
} else {
/*
* Decrypt the remaining of the packet - skip the block we already decoded in order to extract
* the packet length
*/
if (inCipher != null) {
int updateLen = decoderLength + Integer.BYTES - inCipherSize;
inCipher.update(data, inCipherSize, updateLen);
int blocksCount = updateLen / inCipherSize;
inBlocksCount.addAndGet(Math.max(1, blocksCount));
}
validateIncomingMac(data, 0, decoderLength + Integer.BYTES);
}
// Mitigation against CVE-2008-5161 AKA CPNI-957037. But is is highly unlikely that we pass the AAD or MAC checks above.
if (discarding != null) {
throw new SshException(SshConstants.SSH2_DISCONNECT_PROTOCOL_ERROR, discarding);
}
// Increment incoming packet sequence number
seqi = (seqi + 1L) & 0x0ffffffffL;
// Get padding
int pad = decoderBuffer.getUByte();
Buffer packet;
int wpos = decoderBuffer.wpos();
// Decompress if needed
if ((inCompression != null)
&& inCompression.isCompressionExecuted()
&& (isAuthenticated() || (!inCompression.isDelayed()))) {
if (uncompressBuffer == null) {
uncompressBuffer = new SessionWorkBuffer(this);
} else {
uncompressBuffer.forceClear(true);
}
decoderBuffer.wpos(decoderBuffer.rpos() + decoderLength - 1 - pad);
inCompression.uncompress(decoderBuffer, uncompressBuffer);
packet = uncompressBuffer;
} else {
decoderBuffer.wpos(decoderLength + Integer.BYTES - pad);
packet = decoderBuffer;
}
if (log.isTraceEnabled()) {
packet.dumpHex(getSimplifiedLogger(), Level.FINEST,
"decode(" + this + ") packet #" + seqi, this);
}
// Update counters used to track re-keying
inPacketsCount.incrementAndGet();
inBytesCount.addAndGet(packet.available());
// Process decoded packet
handleMessage(packet);
// Set ready to handle next packet
decoderBuffer.rpos(decoderLength + Integer.BYTES + macSize + authSize);
decoderBuffer.wpos(wpos);
decoderBuffer.compact();
decoderState = 0;
} else {
// need more data
break;
}
}
}
}
protected void validateIncomingMac(byte[] data, int offset, int len) throws Exception {
if (inMac == null) {
return;
}
// Update mac with packet id
inMac.updateUInt(seqi);
// Update mac with packet data
inMac.update(data, offset, len);
// Compute mac result
inMac.doFinal(inMacResult, 0);
// Check the computed result with the received mac (just after the packet data)
if (!Mac.equals(inMacResult, 0, data, offset + len, inMacSize)) {
throw new SshException(SshConstants.SSH2_DISCONNECT_MAC_ERROR, "MAC Error");
}
}
/**
* Read the other side identification. This method is specific to the client or server side, but both should call
* {@link #doReadIdentification(Buffer, boolean)} and store the result in the needed property.
*
* @param buffer The {@link Buffer} containing the remote identification
* @return true if the identification has been fully read or false if more data
* is needed
* @throws Exception if an error occurs such as a bad protocol version or unsuccessful KEX was involved
*/
protected abstract boolean readIdentification(Buffer buffer) throws Exception;
/**
* Send the key exchange initialization packet. This packet contains random data along with our proposal.
*
* @param proposal our proposal for key exchange negotiation
* @return the sent packet data which must be kept for later use when deriving the session keys
* @throws Exception if an error occurred sending the packet
*/
protected byte[] sendKexInit(Map proposal) throws Exception {
boolean debugEnabled = log.isDebugEnabled();
if (debugEnabled) {
log.debug("sendKexInit({}) Send SSH_MSG_KEXINIT", this);
}
Buffer buffer = createBuffer(SshConstants.SSH_MSG_KEXINIT);
int p = buffer.wpos();
buffer.wpos(p + SshConstants.MSG_KEX_COOKIE_SIZE);
synchronized (random) {
random.fill(buffer.array(), p, SshConstants.MSG_KEX_COOKIE_SIZE);
}
boolean traceEnabled = log.isTraceEnabled();
if (traceEnabled) {
log.trace("sendKexInit({}) cookie={}",
this, BufferUtils.toHex(buffer.array(), p, SshConstants.MSG_KEX_COOKIE_SIZE, ':'));
}
for (KexProposalOption paramType : KexProposalOption.VALUES) {
String s = proposal.get(paramType);
if (traceEnabled) {
log.trace("sendKexInit({})[{}] {}", this, paramType.getDescription(), s);
}
buffer.putString(GenericUtils.trimToEmpty(s));
}
buffer.putBoolean(false); // first kex packet follows
buffer.putUInt(0L); // reserved (FFU)
ReservedSessionMessagesHandler handler = getReservedSessionMessagesHandler();
IoWriteFuture future = (handler == null) ? null : handler.sendKexInitRequest(this, proposal, buffer);
byte[] data = buffer.getCompactData();
if (future == null) {
writePacket(buffer);
} else {
if (debugEnabled) {
log.debug("sendKexInit({}) KEX handled by reserved messages handler", this);
}
}
return data;
}
/**
* Receive the remote key exchange init message. The packet data is returned for later use.
*
* @param buffer the {@link Buffer} containing the key exchange init packet
* @param proposal the remote proposal to fill
* @return the packet data
* @throws Exception If failed to handle the message
*/
protected byte[] receiveKexInit(Buffer buffer, Map proposal) throws Exception {
// Recreate the packet payload which will be needed at a later time
byte[] d = buffer.array();
byte[] data = new byte[buffer.available() + 1 /* the opcode */];
data[0] = SshConstants.SSH_MSG_KEXINIT;
int size = 6;
int cookieStartPos = buffer.rpos();
System.arraycopy(d, cookieStartPos, data, 1, data.length - 1);
// Skip random cookie data
buffer.rpos(cookieStartPos + SshConstants.MSG_KEX_COOKIE_SIZE);
size += SshConstants.MSG_KEX_COOKIE_SIZE;
boolean traceEnabled = log.isTraceEnabled();
if (traceEnabled) {
log.trace("receiveKexInit({}) cookie={}",
this, BufferUtils.toHex(d, cookieStartPos, SshConstants.MSG_KEX_COOKIE_SIZE, ':'));
}
// Read proposal
for (KexProposalOption paramType : KexProposalOption.VALUES) {
int lastPos = buffer.rpos();
String value = buffer.getString();
if (traceEnabled) {
log.trace("receiveKexInit({})[{}] {}", this, paramType.getDescription(), value);
}
int curPos = buffer.rpos();
int readLen = curPos - lastPos;
proposal.put(paramType, value);
size += readLen;
}
KexExtensionHandler extHandler = getKexExtensionHandler();
if (extHandler != null) {
if (traceEnabled) {
log.trace("receiveKexInit({}) options before handler: {}", this, proposal);
}
extHandler.handleKexInitProposal(this, false, proposal);
if (traceEnabled) {
log.trace("receiveKexInit({}) options after handler: {}", this, proposal);
}
}
firstKexPacketFollows = buffer.getBoolean();
if (traceEnabled) {
log.trace("receiveKexInit({}) first kex packet follows: {}", this, firstKexPacketFollows);
}
long reserved = buffer.getUInt();
if (reserved != 0L) {
if (traceEnabled) {
log.trace("receiveKexInit({}) non-zero reserved value: {}", this, reserved);
}
}
// Return data
byte[] dataShrinked = new byte[size];
System.arraycopy(data, 0, dataShrinked, 0, size);
return dataShrinked;
}
/**
* Prepares the new ciphers, macs and compression algorithms according to the negotiated server and client proposals
* and stores them in {@link #inSettings} and {@link #outSettings}. The new settings do not take effect yet; use
* {@link #setInputEncoding()} or {@link #setOutputEncoding()} for that.
*
* @throws Exception if an error occurs
*/
@SuppressWarnings("checkstyle:VariableDeclarationUsageDistance")
protected void prepareNewKeys() throws Exception {
byte[] k = kex.getK();
byte[] h = kex.getH();
Digest hash = kex.getHash();
boolean debugEnabled = log.isDebugEnabled();
if (sessionId == null) {
sessionId = h.clone();
if (debugEnabled) {
log.debug("prepareNewKeys({}) session ID={}", this, BufferUtils.toHex(':', sessionId));
}
}
Buffer buffer = new ByteArrayBuffer();
buffer.putBytes(k);
buffer.putRawBytes(h);
buffer.putByte((byte) 0x41);
buffer.putRawBytes(sessionId);
int pos = buffer.available();
byte[] buf = buffer.array();
hash.update(buf, 0, pos);
byte[] iv_c2s = hash.digest();
int j = pos - sessionId.length - 1;
buf[j]++;
hash.update(buf, 0, pos);
byte[] iv_s2c = hash.digest();
buf[j]++;
hash.update(buf, 0, pos);
byte[] e_c2s = hash.digest();
buf[j]++;
hash.update(buf, 0, pos);
byte[] e_s2c = hash.digest();
buf[j]++;
hash.update(buf, 0, pos);
byte[] mac_c2s = hash.digest();
buf[j]++;
hash.update(buf, 0, pos);
byte[] mac_s2c = hash.digest();
boolean serverSession = isServerSession();
String value = getNegotiatedKexParameter(KexProposalOption.S2CENC);
Cipher s2ccipher = ValidateUtils.checkNotNull(
NamedFactory.create(getCipherFactories(), value), "Unknown s2c cipher: %s", value);
e_s2c = resizeKey(e_s2c, s2ccipher.getKdfSize(), hash, k, h);
Mac s2cmac;
if (s2ccipher.getAuthenticationTagSize() == 0) {
value = getNegotiatedKexParameter(KexProposalOption.S2CMAC);
s2cmac = NamedFactory.create(getMacFactories(), value);
if (s2cmac == null) {
throw new SshException(SshConstants.SSH2_DISCONNECT_MAC_ERROR, "Unknown s2c MAC: " + value);
}
mac_s2c = resizeKey(mac_s2c, s2cmac.getBlockSize(), hash, k, h);
s2cmac.init(mac_s2c);
} else {
s2cmac = null;
}
value = getNegotiatedKexParameter(KexProposalOption.S2CCOMP);
Compression s2ccomp = NamedFactory.create(getCompressionFactories(), value);
if (s2ccomp == null) {
throw new SshException(SshConstants.SSH2_DISCONNECT_COMPRESSION_ERROR, "Unknown s2c compression: " + value);
}
value = getNegotiatedKexParameter(KexProposalOption.C2SENC);
Cipher c2scipher = ValidateUtils.checkNotNull(
NamedFactory.create(getCipherFactories(), value), "Unknown c2s cipher: %s", value);
e_c2s = resizeKey(e_c2s, c2scipher.getKdfSize(), hash, k, h);
Mac c2smac;
if (c2scipher.getAuthenticationTagSize() == 0) {
value = getNegotiatedKexParameter(KexProposalOption.C2SMAC);
c2smac = NamedFactory.create(getMacFactories(), value);
if (c2smac == null) {
throw new SshException(SshConstants.SSH2_DISCONNECT_MAC_ERROR, "Unknown c2s MAC: " + value);
}
mac_c2s = resizeKey(mac_c2s, c2smac.getBlockSize(), hash, k, h);
c2smac.init(mac_c2s);
} else {
c2smac = null;
}
value = getNegotiatedKexParameter(KexProposalOption.C2SCOMP);
Compression c2scomp = NamedFactory.create(getCompressionFactories(), value);
if (c2scomp == null) {
throw new SshException(SshConstants.SSH2_DISCONNECT_COMPRESSION_ERROR, "Unknown c2s compression: " + value);
}
if (serverSession) {
outSettings = new MessageCodingSettings(s2ccipher, s2cmac, s2ccomp, Cipher.Mode.Encrypt, e_s2c, iv_s2c);
inSettings = new MessageCodingSettings(c2scipher, c2smac, c2scomp, Cipher.Mode.Decrypt, e_c2s, iv_c2s);
} else {
outSettings = new MessageCodingSettings(c2scipher, c2smac, c2scomp, Cipher.Mode.Encrypt, e_c2s, iv_c2s);
inSettings = new MessageCodingSettings(s2ccipher, s2cmac, s2ccomp, Cipher.Mode.Decrypt, e_s2c, iv_s2c);
}
}
/**
* Installs the current prepared {@link #outSettings} so that they are effective and will be applied to any future
* outgoing packet. Clears {@link #outSettings}.
*
* @throws Exception on errors
*/
protected void setOutputEncoding() throws Exception {
if (strictKex) {
if (log.isDebugEnabled()) {
log.debug("setOutputEncoding({}): strict KEX resets output message sequence number from {} to 0", this, seqo);
}
seqo = 0;
}
outCipher = outSettings.getCipher(seqo);
outMac = outSettings.getMac();
outCompression = outSettings.getCompression();
outSettings = null;
outCipherSize = outCipher.getCipherBlockSize();
outMacSize = outMac != null ? outMac.getBlockSize() : 0;
// TODO add support for configurable compression level
outCompression.init(Compression.Type.Deflater, -1);
maxRekeyBlocks.set(determineRekeyBlockLimit(inCipherSize, outCipherSize));
outBytesCount.set(0L);
outPacketsCount.set(0L);
outBlocksCount.set(0L);
lastKeyTimeValue.set(Instant.now());
firstKexPacketFollows = null;
if (log.isDebugEnabled()) {
log.debug("setOutputEncoding({}): cipher {}; mac {}; compression {}; blocks limit {}", this, outCipher, outMac,
outCompression, maxRekeyBlocks);
}
}
/**
* Installs the current prepared {@link #inSettings} so that they are effective and will be applied to any future
* incoming packet. Clears {@link #inSettings}.
*
* @throws Exception on errors
*/
protected void setInputEncoding() throws Exception {
if (strictKex) {
if (log.isDebugEnabled()) {
log.debug("setInputEncoding({}): strict KEX resets input message sequence number from {} to 0", this, seqi);
}
seqi = 0;
}
inCipher = inSettings.getCipher(seqi);
inMac = inSettings.getMac();
inCompression = inSettings.getCompression();
inSettings = null;
inCipherSize = inCipher.getCipherBlockSize();
inMacSize = inMac != null ? inMac.getBlockSize() : 0;
inMacResult = new byte[inMacSize];
// TODO add support for configurable compression level
inCompression.init(Compression.Type.Inflater, -1);
maxRekeyBlocks.set(determineRekeyBlockLimit(inCipherSize, outCipherSize));
inBytesCount.set(0L);
inPacketsCount.set(0L);
inBlocksCount.set(0L);
lastKeyTimeValue.set(Instant.now());
firstKexPacketFollows = null;
if (log.isDebugEnabled()) {
log.debug("setInputEncoding({}): cipher {}; mac {}; compression {}; blocks limit {}", this, inCipher, inMac,
inCompression, maxRekeyBlocks);
}
}
/**
* Compute the number of blocks after which we should re-key again. See RFC 4344.
*
* @param inCipherBlockSize block size of the input cipher
* @param outCipherBlockSize block size of the output cipher
* @return the number of block after which re-keying occur at the latest
* @see RFC 4344, section 3.2
*/
protected long determineRekeyBlockLimit(int inCipherBlockSize, int outCipherBlockSize) {
// see https://tools.ietf.org/html/rfc4344#section-3.2
// select the lowest cipher size
long rekeyBlocksLimit = CoreModuleProperties.REKEY_BLOCKS_LIMIT.getRequired(this);
if (rekeyBlocksLimit <= 0) {
// Default per RFC 4344
int minCipherBlockBytes = Math.min(inCipherSize, outCipherSize);
if (minCipherBlockBytes >= 16) {
rekeyBlocksLimit = 1L << Math.min(minCipherBlockBytes * 2, 63);
} else {
// With a block size of 8 we'd end up with 2^16. That would re-key very often.
// RFC 4344: "If L is less than 128 [...], then, although it may be too
// expensive to rekey every 2**(L/4) blocks, it is still advisable for SSH
// implementations to follow the original recommendation in [RFC4253]: rekey at
// least once for every gigabyte of transmitted data."
//
// Note that chacha20-poly1305 has a block size of 8. The OpenSSH recommendation
// is: "ChaCha20 must never reuse a {key, nonce} for encryption nor may it be
// used to encrypt more than 2^70 bytes under the same {key, nonce}. The
// SSH Transport protocol (RFC4253) recommends a far more conservative
// rekeying every 1GB of data sent or received. If this recommendation
// is followed, then [email protected] requires no special
// handling in this area."
rekeyBlocksLimit = (1L << 30) / minCipherBlockBytes; // 1GB
}
}
return rekeyBlocksLimit;
}
/**
* Send a {@code SSH_MSG_UNIMPLEMENTED} packet. This packet should contain the sequence id of the unsupported
* packet: this number is assumed to be the last packet received.
*
* @param cmd The un-implemented command value
* @param buffer The {@link Buffer} that contains the command. Note: the buffer's read position is just
* beyond the command.
* @return An {@link IoWriteFuture} that can be used to wait for packet write completion - {@code null} if
* the registered {@link ReservedSessionMessagesHandler} decided to handle the command internally
* @throws Exception if an error occurred while handling the packet.
* @see #sendNotImplemented(long)
*/
protected IoWriteFuture notImplemented(int cmd, Buffer buffer) throws Exception {
if (doInvokeUnimplementedMessageHandler(cmd, buffer)) {
return null;
}
return sendNotImplemented(seqi - 1L);
}
/**
* Given a KEX proposal and a {@link KexProposalOption}, removes all occurrences of a value from a comma-separated
* value list.
*
* @param options {@link Map} holding the Kex proposal
* @param option {@link KexProposalOption} to modify
* @param toRemove value to remove
* @return {@code true} if the option contained the value (and it was removed); {@code false} otherwise
*/
protected boolean removeValue(Map options, KexProposalOption option, String toRemove) {
String val = options.get(option);
Set algorithms = new LinkedHashSet<>(Arrays.asList(val.split(",")));
boolean result = algorithms.remove(toRemove);
if (result) {
options.put(option, algorithms.stream().collect(Collectors.joining(",")));
}
return result;
}
/**
* Compute the negotiated proposals by merging the client and server proposal. The negotiated proposal will also be
* stored in the {@link #negotiationResult} property.
*
* @return The negotiated options {@link Map}
* @throws Exception If negotiation failed
*/
protected Map negotiate() throws Exception {
Map c2sOptions = getClientKexProposals();
Map s2cOptions = getServerKexProposals();
signalNegotiationStart(c2sOptions, s2cOptions);
// Make modifiable. Strict KEX flags are to be heeded only in initial KEX, and to be ignored afterwards.
c2sOptions = new EnumMap<>(c2sOptions);
s2cOptions = new EnumMap<>(s2cOptions);
boolean strictKexClient = removeValue(c2sOptions, KexProposalOption.ALGORITHMS,
KexExtensions.STRICT_KEX_CLIENT_EXTENSION);
boolean strictKexServer = removeValue(s2cOptions, KexProposalOption.ALGORITHMS,
KexExtensions.STRICT_KEX_SERVER_EXTENSION);
if (removeValue(c2sOptions, KexProposalOption.ALGORITHMS, KexExtensions.STRICT_KEX_SERVER_EXTENSION)
&& !initialKexDone) {
log.warn("negotiate({}) client proposal contains server flag {}; will be ignored", this,
KexExtensions.STRICT_KEX_SERVER_EXTENSION);
}
if (removeValue(s2cOptions, KexProposalOption.ALGORITHMS, KexExtensions.STRICT_KEX_CLIENT_EXTENSION)
&& !initialKexDone) {
log.warn("negotiate({}) server proposal contains client flag {}; will be ignored", this,
KexExtensions.STRICT_KEX_CLIENT_EXTENSION);
}
// Make unmodifiable again
c2sOptions = Collections.unmodifiableMap(c2sOptions);
s2cOptions = Collections.unmodifiableMap(s2cOptions);
Map guess = new EnumMap<>(KexProposalOption.class);
Map negotiatedGuess = Collections.unmodifiableMap(guess);
try {
boolean debugEnabled = log.isDebugEnabled();
boolean traceEnabled = log.isTraceEnabled();
if (!initialKexDone) {
strictKex = strictKexClient && strictKexServer;
if (debugEnabled) {
log.debug("negotiate({}) strict KEX={} client={} server={}", this, strictKex, strictKexClient,
strictKexServer);
}
if (strictKex && initialKexInitSequenceNumber != 1) {
throw new SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
"Strict KEX negotiated but sequence number of first KEX_INIT received is not 1: "
+ initialKexInitSequenceNumber);
}
}
SessionDisconnectHandler discHandler = getSessionDisconnectHandler();
KexExtensionHandler extHandler = getKexExtensionHandler();
for (KexProposalOption paramType : KexProposalOption.VALUES) {
String clientParamValue = c2sOptions.get(paramType);
String serverParamValue = s2cOptions.get(paramType);
String[] c = GenericUtils.split(clientParamValue, ',');
String[] s = GenericUtils.split(serverParamValue, ',');
/*
* According to https://tools.ietf.org/html/rfc8308#section-2.2:
*
* Implementations MAY disconnect if the counterpart sends an incorrect (KEX extension) indicator
*
* TODO - for now we do not enforce this
*/
for (String ci : c) {
for (String si : s) {
if (ci.equals(si)) {
guess.put(paramType, ci);
break;
}
}
String value = guess.get(paramType);
if (value != null) {
break;
}
}
// check if reached an agreement
String value = guess.get(paramType);
if (extHandler != null) {
extHandler.handleKexExtensionNegotiation(
this, paramType, value, c2sOptions, clientParamValue, s2cOptions, serverParamValue);
}
if (value != null) {
if (traceEnabled) {
log.trace("negotiate({})[{}] guess={} (client={} / server={})",
this, paramType.getDescription(), value, clientParamValue, serverParamValue);
}
continue;
}
try {
if ((discHandler != null)
&& discHandler.handleKexDisconnectReason(
this, c2sOptions, s2cOptions, negotiatedGuess, paramType)) {
if (debugEnabled) {
log.debug("negotiate({}) ignore missing value for KEX option={}", this, paramType);
}
continue;
}
} catch (IOException | RuntimeException e) {
// If disconnect handler throws an exception continue with the disconnect
debug("negotiate({}) failed ({}) to invoke disconnect handler due to mismatched KEX option={}: {}",
this, e.getClass().getSimpleName(), paramType, e.getMessage(), e);
}
String message = "Unable to negotiate key exchange for " + paramType.getDescription()
+ " (client: " + clientParamValue + " / server: " + serverParamValue + ")";
// OK if could not negotiate languages
if (KexProposalOption.S2CLANG.equals(paramType) || KexProposalOption.C2SLANG.equals(paramType)) {
if (traceEnabled) {
log.trace("negotiate({}) {}", this, message);
}
} else {
throw new SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED, message);
}
}
/*
* According to https://tools.ietf.org/html/rfc8308#section-2.2:
*
* If "ext-info-c" or "ext-info-s" ends up being negotiated as a key exchange method, the parties MUST
* disconnect.
*/
String kexOption = guess.get(KexProposalOption.ALGORITHMS);
if (KexExtensions.IS_KEX_EXTENSION_SIGNAL.test(kexOption)) {
if ((discHandler != null)
&& discHandler.handleKexDisconnectReason(
this, c2sOptions, s2cOptions, negotiatedGuess, KexProposalOption.ALGORITHMS)) {
if (debugEnabled) {
log.debug("negotiate({}) ignore violating {} KEX option={}", this, KexProposalOption.ALGORITHMS,
kexOption);
}
} else {
throw new SshException(SshConstants.SSH2_DISCONNECT_KEY_EXCHANGE_FAILED,
"Illegal KEX option negotiated: " + kexOption);
}
}
} catch (IOException | RuntimeException | Error e) {
signalNegotiationEnd(c2sOptions, s2cOptions, negotiatedGuess, e);
throw e;
}
signalNegotiationEnd(c2sOptions, s2cOptions, negotiatedGuess, null);
return setNegotiationResult(guess);
}
protected Map setNegotiationResult(Map guess) {
synchronized (negotiationResult) {
if (!negotiationResult.isEmpty()) {
negotiationResult.clear(); // debug breakpoint
}
negotiationResult.putAll(guess);
}
if (log.isDebugEnabled()) {
guess.forEach((option, value) -> log.debug("setNegotiationResult({}) Kex: {} = {}", this,
option.getDescription(), value));
}
return guess;
}
/**
* Indicates the reception of a {@code SSH_MSG_REQUEST_SUCCESS} message
*
* @param buffer The {@link Buffer} containing the message data
* @throws Exception If failed to handle the message
*/
protected void requestSuccess(Buffer buffer) throws Exception {
resetIdleTimeout();
// Remove at end
GlobalRequestFuture request = pendingGlobalRequests.pollLast();
if (request != null) {
// use a copy of the original data in case it is re-used on return
Buffer resultBuf = ByteArrayBuffer.getCompactClone(buffer.array(), buffer.rpos(), buffer.available());
GlobalRequestFuture.ReplyHandler handler = request.getHandler();
if (handler != null) {
handler.accept(SshConstants.SSH_MSG_REQUEST_SUCCESS, resultBuf);
} else {
request.setValue(resultBuf);
}
}
}
/**
* Indicates the reception of a {@code SSH_MSG_REQUEST_FAILURE} message
*
* @param buffer The {@link Buffer} containing the message data
* @throws Exception If failed to handle the message
*/
protected void requestFailure(Buffer buffer) throws Exception {
resetIdleTimeout();
// Remove at end
GlobalRequestFuture request = pendingGlobalRequests.pollLast();
if (request != null) {
GlobalRequestFuture.ReplyHandler handler = request.getHandler();
if (handler != null) {
Buffer resultBuf = ByteArrayBuffer.getCompactClone(buffer.array(), buffer.rpos(), buffer.available());
handler.accept(SshConstants.SSH_MSG_REQUEST_FAILURE, resultBuf);
} else {
request.setValue(new GlobalRequestException(SshConstants.SSH_MSG_REQUEST_FAILURE));
}
}
}
@Override
public void addSessionListener(SessionListener listener) {
SessionListener.validateListener(listener);
// avoid race conditions on notifications while session is being closed
if (!isOpen()) {
log.warn("addSessionListener({})[{}] ignore registration while session is closing", this, listener);
return;
}
if (this.sessionListeners.add(listener)) {
if (log.isTraceEnabled()) {
log.trace("addSessionListener({})[{}] registered", this, listener);
}
} else {
if (log.isTraceEnabled()) {
log.trace("addSessionListener({})[{}] ignored duplicate", this, listener);
}
}
}
@Override
public void removeSessionListener(SessionListener listener) {
if (listener == null) {
return;
}
SessionListener.validateListener(listener);
if (this.sessionListeners.remove(listener)) {
if (log.isTraceEnabled()) {
log.trace("removeSessionListener({})[{}] removed", this, listener);
}
} else {
if (log.isTraceEnabled()) {
log.trace("removeSessionListener({})[{}] not registered", this, listener);
}
}
}
@Override
public SessionListener getSessionListenerProxy() {
return sessionListenerProxy;
}
@Override
public void addChannelListener(ChannelListener listener) {
ChannelListener.validateListener(listener);
// avoid race conditions on notifications while session is being closed
if (!isOpen()) {
log.warn("addChannelListener({})[{}] ignore registration while session is closing", this, listener);
return;
}
if (this.channelListeners.add(listener)) {
if (log.isTraceEnabled()) {
log.trace("addChannelListener({})[{}] registered", this, listener);
}
} else {
if (log.isTraceEnabled()) {
log.trace("addChannelListener({})[{}] ignored duplicate", this, listener);
}
}
}
@Override
public void removeChannelListener(ChannelListener listener) {
if (listener == null) {
return;
}
ChannelListener.validateListener(listener);
if (this.channelListeners.remove(listener)) {
if (log.isTraceEnabled()) {
log.trace("removeChannelListener({})[{}] removed", this, listener);
}
} else {
if (log.isTraceEnabled()) {
log.trace("removeChannelListener({})[{}] not registered", this, listener);
}
}
}
@Override
public ChannelListener getChannelListenerProxy() {
return channelListenerProxy;
}
@Override
public PortForwardingEventListener getPortForwardingEventListenerProxy() {
return tunnelListenerProxy;
}
@Override
public void addPortForwardingEventListener(PortForwardingEventListener listener) {
PortForwardingEventListener.validateListener(listener);
// avoid race conditions on notifications while session is being closed
if (!isOpen()) {
log.warn("addPortForwardingEventListener({})[{}] ignore registration while session is closing", this, listener);
return;
}
if (this.tunnelListeners.add(listener)) {
if (log.isTraceEnabled()) {
log.trace("addPortForwardingEventListener({})[{}] registered", this, listener);
}
} else {
if (log.isTraceEnabled()) {
log.trace("addPortForwardingEventListener({})[{}] ignored duplicate", this, listener);
}
}
}
@Override
public void removePortForwardingEventListener(PortForwardingEventListener listener) {
if (listener == null) {
return;
}
PortForwardingEventListener.validateListener(listener);
if (this.tunnelListeners.remove(listener)) {
if (log.isTraceEnabled()) {
log.trace("removePortForwardingEventListener({})[{}] removed", this, listener);
}
} else {
if (log.isTraceEnabled()) {
log.trace("removePortForwardingEventListener({})[{}] not registered", this, listener);
}
}
}
@Override
public KeyExchangeFuture reExchangeKeys() throws IOException {
try {
requestNewKeysExchange();
} catch (GeneralSecurityException e) {
debug("reExchangeKeys({}) failed ({}) to request new keys: {}",
this, e.getClass().getSimpleName(), e.getMessage(), e);
throw ValidateUtils.initializeExceptionCause(
new ProtocolException("Failed (" + e.getClass().getSimpleName() + ")"
+ " to generate keys for exchange: " + e.getMessage()),
e);
} catch (Exception e) {
ExceptionUtils.rethrowAsIoException(e);
return null; // actually dead code
}
return ValidateUtils.checkNotNull(
kexFutureHolder.get(), "No current KEX future on state=%s", kexState);
}
/**
* Checks if a re-keying is required and if so initiates it
*
* @return A {@link KeyExchangeFuture} to wait for the initiated exchange or {@code null} if no need to
* re-key or an exchange is already in progress
* @throws Exception If failed load/generate the keys or send the request
* @see #isRekeyRequired()
* @see #requestNewKeysExchange()
*/
protected KeyExchangeFuture checkRekey() throws Exception {
return isRekeyRequired() ? requestNewKeysExchange() : null;
}
/**
* Initiates a new keys exchange if one not already in progress
*
* @return A {@link KeyExchangeFuture} to wait for the initiated exchange or {@code null} if an exchange
* is already in progress
* @throws Exception If failed to load/generate the keys or send the request
*/
protected KeyExchangeFuture requestNewKeysExchange() throws Exception {
boolean kexRunning = kexHandler.updateState(() -> {
boolean isRunning = !kexState.compareAndSet(KexState.DONE, KexState.INIT);
if (!isRunning) {
kexHandler.initNewKeyExchange();
}
return Boolean.valueOf(isRunning);
}).booleanValue();
if (kexRunning) {
if (log.isDebugEnabled()) {
log.debug("requestNewKeysExchange({}) KEX state not DONE: {}", this, kexState);
}
return null;
}
log.info("requestNewKeysExchange({}) Initiating key re-exchange", this);
DefaultKeyExchangeFuture newFuture = new DefaultKeyExchangeFuture(toString(), null);
DefaultKeyExchangeFuture kexFuture = kexFutureHolder.getAndSet(newFuture);
if (kexFuture != null) {
// Should actually never do anything. We don't reset the kexFuture at the end of KEX, and we do check for a
// running KEX above. The old future should in all cases be fulfilled already.
kexFuture.setValue(new SshException("New KEX started while previous one still ongoing"));
}
sendKexInit();
return newFuture;
}
protected boolean isRekeyRequired() {
if ((!isOpen()) || isClosing() || isClosed()) {
return false;
}
KexState curState = kexState.get();
if (!KexState.DONE.equals(curState)) {
return false;
}
return isRekeyTimeIntervalExceeded()
|| isRekeyPacketCountsExceeded()
|| isRekeyBlocksCountExceeded()
|| isRekeyDataSizeExceeded();
}
protected boolean isRekeyTimeIntervalExceeded() {
if (GenericUtils.isNegativeOrNull(maxRekeyInterval)) {
return false; // disabled
}
Instant now = Instant.now();
Duration rekeyDiff = Duration.between(lastKeyTimeValue.get(), now);
boolean rekey = rekeyDiff.compareTo(maxRekeyInterval) > 0;
if (rekey) {
if (log.isDebugEnabled()) {
log.debug("isRekeyTimeIntervalExceeded({}) re-keying: last={}, now={}, diff={}, max={}",
this, lastKeyTimeValue.get(), now, rekeyDiff, maxRekeyInterval);
}
}
return rekey;
}
protected boolean isRekeyPacketCountsExceeded() {
if (maxRekyPackets <= 0L) {
return false; // disabled
}
boolean rekey = (inPacketsCount.get() > maxRekyPackets)
|| (outPacketsCount.get() > maxRekyPackets);
if (rekey) {
if (log.isDebugEnabled()) {
log.debug("isRekeyPacketCountsExceeded({}) re-keying: in={}, out={}, max={}",
this, inPacketsCount, outPacketsCount, maxRekyPackets);
}
}
return rekey;
}
protected boolean isRekeyDataSizeExceeded() {
if (maxRekeyBytes <= 0L) {
return false;
}
boolean rekey = (inBytesCount.get() > maxRekeyBytes) || (outBytesCount.get() > maxRekeyBytes);
if (rekey) {
if (log.isDebugEnabled()) {
log.debug("isRekeyDataSizeExceeded({}) re-keying: in={}, out={}, max={}",
this, inBytesCount, outBytesCount, maxRekeyBytes);
}
}
return rekey;
}
protected boolean isRekeyBlocksCountExceeded() {
long maxBlocks = maxRekeyBlocks.get();
if (maxBlocks <= 0L) {
return false;
}
boolean rekey = (inBlocksCount.get() > maxBlocks) || (outBlocksCount.get() > maxBlocks);
if (rekey) {
if (log.isDebugEnabled()) {
log.debug("isRekeyBlocksCountExceeded({}) re-keying: in={}, out={}, max={}",
this, inBlocksCount, outBlocksCount, maxBlocks);
}
}
return rekey;
}
@Override
protected String resolveSessionKexProposal(String hostKeyTypes) throws IOException {
String proposal = super.resolveSessionKexProposal(hostKeyTypes);
// see https://tools.ietf.org/html/rfc8308
KexExtensionHandler extHandler = getKexExtensionHandler();
if ((extHandler == null) || (!extHandler.isKexExtensionsAvailable(this, AvailabilityPhase.PROPOSAL))) {
return proposal;
}
String extType = isServerSession() ? KexExtensions.SERVER_KEX_EXTENSION : KexExtensions.CLIENT_KEX_EXTENSION;
if (GenericUtils.isEmpty(proposal)) {
return extType;
} else {
return proposal + "," + extType;
}
}
protected Map doStrictKexProposal(Map proposal) {
String value = proposal.get(KexProposalOption.ALGORITHMS);
String askForStrictKex = isServerSession()
? KexExtensions.STRICT_KEX_SERVER_EXTENSION
: KexExtensions.STRICT_KEX_CLIENT_EXTENSION;
if (!initialKexDone) {
// On the initial KEX, include the strict KEX flag
if (GenericUtils.isEmpty(value)) {
value = askForStrictKex;
} else {
value += "," + askForStrictKex;
}
} else if (!GenericUtils.isEmpty(value)) {
// On subsequent KEXes, do not include ext-info-c/ext-info-s or the strict KEX flag in the proposal.
List algorithms = new ArrayList<>(Arrays.asList(value.split(",")));
String extType = isServerSession() ? KexExtensions.SERVER_KEX_EXTENSION : KexExtensions.CLIENT_KEX_EXTENSION;
boolean changed = algorithms.remove(extType);
changed |= algorithms.remove(askForStrictKex);
if (changed) {
value = algorithms.stream().collect(Collectors.joining(","));
}
}
proposal.put(KexProposalOption.ALGORITHMS, value);
return proposal;
}
protected byte[] sendKexInit() throws Exception {
Map proposal = doStrictKexProposal(getKexProposal());
byte[] seed;
synchronized (kexState) {
DefaultKeyExchangeFuture initFuture = kexInitializedFuture;
if (initFuture == null) {
initFuture = new DefaultKeyExchangeFuture(toString(), null);
kexInitializedFuture = initFuture;
}
try {
seed = sendKexInit(proposal);
setKexSeed(seed);
initFuture.setValue(Boolean.TRUE);
} catch (Exception e) {
initFuture.setValue(e);
throw e;
}
}
if (log.isTraceEnabled()) {
log.trace("sendKexInit({}) proposal={} seed: {}", this, proposal, BufferUtils.toHex(':', seed));
}
return seed;
}
protected byte[] getClientKexData() {
synchronized (kexState) {
return (clientKexData == null) ? null : clientKexData.clone();
}
}
protected void setClientKexData(byte[] data) {
ValidateUtils.checkNotNullAndNotEmpty(data, "No client KEX seed");
synchronized (kexState) {
clientKexData = data.clone();
}
}
protected byte[] getServerKexData() {
synchronized (kexState) {
return (serverKexData == null) ? null : serverKexData.clone();
}
}
protected void setServerKexData(byte[] data) {
ValidateUtils.checkNotNullAndNotEmpty(data, "No server KEX seed");
synchronized (kexState) {
serverKexData = data.clone();
}
}
/**
* @param seed The result of the KEXINIT handshake - required for correct session key establishment
*/
protected abstract void setKexSeed(byte... seed);
/**
* Indicates the the key exchange is completed and the exchanged keys can now be verified - e.g., client can verify
* the server's key
*
* @throws IOException If validation failed
*/
protected abstract void checkKeys() throws IOException;
protected byte[] receiveKexInit(Buffer buffer) throws Exception {
Map proposal = new EnumMap<>(KexProposalOption.class);
if (!initialKexDone) {
initialKexInitSequenceNumber = seqi;
}
byte[] seed;
synchronized (kexState) {
seed = receiveKexInit(buffer, proposal);
receiveKexInit(proposal, seed);
}
if (log.isTraceEnabled()) {
log.trace("receiveKexInit({}) proposal={} seed: {}",
this, proposal, BufferUtils.toHex(':', seed));
}
return seed;
}
protected abstract void receiveKexInit(
Map proposal, byte[] seed)
throws IOException;
/**
* Retrieve the SSH session from the I/O session. If the session has not been attached, an exception will be thrown
*
* @param ioSession The {@link IoSession}
* @return The SSH session attached to the I/O session
* @see #getSession(IoSession, boolean)
* @throws MissingAttachedSessionException if no attached SSH session
*/
public static AbstractSession getSession(IoSession ioSession)
throws MissingAttachedSessionException {
return getSession(ioSession, false);
}
/**
* Attach an SSH {@link AbstractSession} to the I/O session
*
* @param ioSession The {@link IoSession}
* @param session The SSH session to attach
* @throws MultipleAttachedSessionException If a previous session already attached
*/
public static void attachSession(IoSession ioSession, AbstractSession session)
throws MultipleAttachedSessionException {
Objects.requireNonNull(ioSession, "No I/O session");
Objects.requireNonNull(session, "No SSH session");
Object prev = ioSession.setAttributeIfAbsent(SESSION, session);
if (prev != null) {
throw new MultipleAttachedSessionException(
"Multiple attached session to " + ioSession + ": " + prev + " and " + session);
}
}
/**
* Retrieve the session SSH from the I/O session. If the session has not been attached and allowNull is
* false, an exception will be thrown, otherwise a {@code null} will be returned.
*
* @param ioSession The {@link IoSession}
* @param allowNull If true, a {@code null} value may be returned if no session
* is attached
* @return the session attached to the I/O session or {@code null}
* @throws MissingAttachedSessionException if no attached session and allowNull=false
*/
public static AbstractSession getSession(IoSession ioSession, boolean allowNull)
throws MissingAttachedSessionException {
AbstractSession session = (AbstractSession) ioSession.getAttribute(SESSION);
if ((session == null) && (!allowNull)) {
throw new MissingAttachedSessionException("No session attached to " + ioSession);
}
return session;
}
/**
* Message encoding or decoding settings as determined at the end of a key exchange.
*/
protected static class MessageCodingSettings {
private final Cipher cipher;
private final Mac mac;
private final Compression compression;
private final Cipher.Mode mode;
private byte[] key;
private byte[] iv;
public MessageCodingSettings(Cipher cipher, Mac mac, Compression compression, Cipher.Mode mode, byte[] key, byte[] iv) {
this.cipher = cipher;
this.mac = mac;
this.compression = compression;
this.mode = mode;
this.key = key.clone();
this.iv = iv.clone();
}
private void initCipher(long packetSequenceNumber) throws Exception {
if (key != null) {
if (cipher.getAlgorithm().startsWith("ChaCha")) {
BufferUtils.putLong(packetSequenceNumber, iv, 0, iv.length);
}
cipher.init(mode, key, iv);
key = null;
}
}
/**
* Get the {@link Cipher}.
*
* @param packetSequenceNumber SSH packet sequence number for initializing the cipher. Pass {@link #seqo} if
* the cipher is to be used for output, {@link #seqi} otherwise.
* @return the fully initialized cipher
* @throws Exception if the cipher cannot be initialized
*/
public Cipher getCipher(long packetSequenceNumber) throws Exception {
initCipher(packetSequenceNumber);
return cipher;
}
public Mac getMac() {
return mac;
}
public Compression getCompression() {
return compression;
}
}
}
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