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Ganymed SSH-2: Java based SSH-2 Protocol Implementation
/*
* Copyright (c) 2006-2013 Christian Plattner. All rights reserved.
* Please refer to the LICENSE.txt for licensing details.
*/
package ch.ethz.ssh2.transport;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetAddress;
import java.net.InetSocketAddress;
import java.net.Socket;
import java.net.SocketTimeoutException;
import java.net.UnknownHostException;
import java.security.SecureRandom;
import java.util.List;
import java.util.Vector;
import ch.ethz.ssh2.ConnectionInfo;
import ch.ethz.ssh2.ConnectionMonitor;
import ch.ethz.ssh2.DHGexParameters;
import ch.ethz.ssh2.HTTPProxyData;
import ch.ethz.ssh2.HTTPProxyException;
import ch.ethz.ssh2.ProxyData;
import ch.ethz.ssh2.ServerHostKeyVerifier;
import ch.ethz.ssh2.crypto.Base64;
import ch.ethz.ssh2.crypto.CryptoWishList;
import ch.ethz.ssh2.crypto.cipher.BlockCipher;
import ch.ethz.ssh2.crypto.digest.MAC;
import ch.ethz.ssh2.log.Logger;
import ch.ethz.ssh2.packets.PacketDisconnect;
import ch.ethz.ssh2.packets.Packets;
import ch.ethz.ssh2.packets.TypesReader;
import ch.ethz.ssh2.server.ServerConnectionState;
import ch.ethz.ssh2.signature.DSAPrivateKey;
import ch.ethz.ssh2.signature.RSAPrivateKey;
import ch.ethz.ssh2.util.StringEncoder;
import ch.ethz.ssh2.util.Tokenizer;
/*
* Yes, the "standard" is a big mess. On one side, the say that arbitary channel
* packets are allowed during kex exchange, on the other side we need to blindly
* ignore the next _packet_ if the KEX guess was wrong. Where do we know from that
* the next packet is not a channel data packet? Yes, we could check if it is in
* the KEX range. But the standard says nothing about this. The OpenSSH guys
* block local "normal" traffic during KEX. That's fine - however, they assume
* that the other side is doing the same. During re-key, if they receive traffic
* other than KEX, they become horribly irritated and kill the connection. Since
* we are very likely going to communicate with OpenSSH servers, we have to play
* the same game - even though we could do better.
*
* btw: having stdout and stderr on the same channel, with a shared window, is
* also a VERY good idea... =(
*/
/**
* TransportManager.
*
* @author Christian Plattner
* @version $Id: TransportManager.java 47 2013-07-31 23:59:52Z [email protected] $
*/
public class TransportManager
{
private static final Logger log = Logger.getLogger(TransportManager.class);
private static class HandlerEntry
{
MessageHandler mh;
int low;
int high;
}
private final List asynchronousQueue = new Vector();
private Thread asynchronousThread = null;
private boolean asynchronousPending = false;
class AsynchronousEntry
{
public byte[] msg;
public Runnable run;
public AsynchronousEntry(byte[] msg, Runnable run)
{
this.msg = msg;
this.run = run;
}
}
class AsynchronousWorker extends Thread
{
@Override
public void run()
{
while (true)
{
AsynchronousEntry item = null;
synchronized (asynchronousQueue)
{
if (asynchronousQueue.size() == 0)
{
/* Only now we may reset the flag, since we are sure that all queued items
* have been sent (there is a slight delay between de-queuing and sending,
* this is why we need this flag! See code below. Sending takes place outside
* of this lock, this is why a test for size()==0 (from another thread) does not ensure
* that all messages have been sent.
*/
asynchronousPending = false;
/* Notify any senders that they can proceed, all async messages have been delivered */
asynchronousQueue.notifyAll();
/* After the queue is empty for about 2 seconds, stop this thread */
try
{
asynchronousQueue.wait(2000);
}
catch (InterruptedException ignore)
{
}
if (asynchronousQueue.size() == 0)
{
asynchronousThread = null;
return;
}
}
item = asynchronousQueue.remove(0);
}
/* The following invocation may throw an IOException.
* There is no point in handling it - it simply means
* that the connection has a problem and we should stop
* sending asynchronously messages. We do not need to signal that
* we have exited (asynchronousThread = null): further
* messages in the queue cannot be sent by this or any
* other thread.
* Other threads will sooner or later (when receiving or
* sending the next message) get the same IOException and
* get to the same conclusion.
*/
try
{
sendMessageImmediate(item.msg);
}
catch (IOException e)
{
return;
}
if (item.run != null)
{
try
{
item.run.run();
}
catch (Exception ignore)
{
}
}
}
}
}
private Socket sock = new Socket();
private final Object connectionSemaphore = new Object();
private boolean flagKexOngoing = false;
private boolean connectionClosed = false;
private Throwable reasonClosedCause = null;
private TransportConnection tc;
private KexManager km;
private final List messageHandlers = new Vector();
private Thread receiveThread;
private List connectionMonitors = new Vector();
private boolean monitorsWereInformed = false;
/**
* There were reports that there are JDKs which use
* the resolver even though one supplies a dotted IP
* address in the Socket constructor. That is why we
* try to generate the InetAdress "by hand".
*
* @param host
* @return the InetAddress
* @throws UnknownHostException
*/
private static InetAddress createInetAddress(String host) throws UnknownHostException
{
/* Check if it is a dotted IP4 address */
InetAddress addr = parseIPv4Address(host);
if (addr != null)
{
return addr;
}
return InetAddress.getByName(host);
}
private static InetAddress parseIPv4Address(String host) throws UnknownHostException
{
if (host == null)
{
return null;
}
String[] quad = Tokenizer.parseTokens(host, '.');
if ((quad == null) || (quad.length != 4))
{
return null;
}
byte[] addr = new byte[4];
for (int i = 0; i < 4; i++)
{
int part = 0;
if ((quad[i].length() == 0) || (quad[i].length() > 3))
{
return null;
}
for (int k = 0; k < quad[i].length(); k++)
{
char c = quad[i].charAt(k);
/* No, Character.isDigit is not the same */
if ((c < '0') || (c > '9'))
{
return null;
}
part = part * 10 + (c - '0');
}
if (part > 255) /* 300.1.2.3 is invalid =) */
{
return null;
}
addr[i] = (byte) part;
}
return InetAddress.getByAddress(host, addr);
}
public int getPacketOverheadEstimate()
{
return tc.getPacketOverheadEstimate();
}
public void setTcpNoDelay(boolean state) throws IOException
{
sock.setTcpNoDelay(state);
}
public void setSoTimeout(int timeout) throws IOException
{
sock.setSoTimeout(timeout);
}
public ConnectionInfo getConnectionInfo(int kexNumber) throws IOException
{
return km.getOrWaitForConnectionInfo(kexNumber);
}
public Throwable getReasonClosedCause()
{
synchronized (connectionSemaphore)
{
return reasonClosedCause;
}
}
public byte[] getSessionIdentifier()
{
return km.sessionId;
}
public void close(Throwable cause, boolean useDisconnectPacket)
{
if (useDisconnectPacket == false)
{
/* OK, hard shutdown - do not aquire the semaphore,
* perhaps somebody is inside (and waits until the remote
* side is ready to accept new data). */
try
{
sock.close();
}
catch (IOException ignore)
{
}
/* OK, whoever tried to send data, should now agree that
* there is no point in further waiting =)
* It is safe now to aquire the semaphore.
*/
}
synchronized (connectionSemaphore)
{
if (connectionClosed == false)
{
if (useDisconnectPacket == true)
{
try
{
byte[] msg = new PacketDisconnect(Packets.SSH_DISCONNECT_BY_APPLICATION, cause.getMessage(), "")
.getPayload();
if (tc != null)
{
tc.sendMessage(msg);
}
}
catch (IOException ignore)
{
}
try
{
sock.close();
}
catch (IOException ignore)
{
}
}
connectionClosed = true;
reasonClosedCause = cause; /* may be null */
}
connectionSemaphore.notifyAll();
}
/* No check if we need to inform the monitors */
List monitors = new Vector();
synchronized (this)
{
/* Short term lock to protect "connectionMonitors"
* and "monitorsWereInformed"
* (they may be modified concurrently)
*/
if (monitorsWereInformed == false)
{
monitorsWereInformed = true;
monitors.addAll(connectionMonitors);
}
}
for (ConnectionMonitor cmon : monitors)
{
try
{
cmon.connectionLost(reasonClosedCause);
}
catch (Exception ignore)
{
}
}
}
private static Socket establishConnection(String hostname, int port, ProxyData proxyData, int connectTimeout)
throws IOException
{
/* See the comment for createInetAddress() */
if (proxyData == null)
{
InetAddress addr = createInetAddress(hostname);
Socket s = new Socket();
s.connect(new InetSocketAddress(addr, port), connectTimeout);
return s;
}
if (proxyData instanceof HTTPProxyData)
{
HTTPProxyData pd = (HTTPProxyData) proxyData;
/* At the moment, we only support HTTP proxies */
InetAddress addr = createInetAddress(pd.proxyHost);
Socket s = new Socket();
s.connect(new InetSocketAddress(addr, pd.proxyPort), connectTimeout);
/* OK, now tell the proxy where we actually want to connect to */
StringBuilder sb = new StringBuilder();
sb.append("CONNECT ");
sb.append(hostname);
sb.append(':');
sb.append(port);
sb.append(" HTTP/1.0\r\n");
if ((pd.proxyUser != null) && (pd.proxyPass != null))
{
String credentials = pd.proxyUser + ":" + pd.proxyPass;
char[] encoded = Base64.encode(StringEncoder.GetBytes(credentials));
sb.append("Proxy-Authorization: Basic ");
sb.append(encoded);
sb.append("\r\n");
}
if (pd.requestHeaderLines != null)
{
for (int i = 0; i < pd.requestHeaderLines.length; i++)
{
if (pd.requestHeaderLines[i] != null)
{
sb.append(pd.requestHeaderLines[i]);
sb.append("\r\n");
}
}
}
sb.append("\r\n");
OutputStream out = s.getOutputStream();
out.write(StringEncoder.GetBytes(sb.toString()));
out.flush();
/* Now parse the HTTP response */
byte[] buffer = new byte[1024];
InputStream in = s.getInputStream();
int len = ClientServerHello.readLineRN(in, buffer);
String httpReponse = StringEncoder.GetString(buffer, 0, len);
if (httpReponse.startsWith("HTTP/") == false)
{
throw new IOException("The proxy did not send back a valid HTTP response.");
}
/* "HTTP/1.X XYZ X" => 14 characters minimum */
if ((httpReponse.length() < 14) || (httpReponse.charAt(8) != ' ') || (httpReponse.charAt(12) != ' '))
{
throw new IOException("The proxy did not send back a valid HTTP response.");
}
int errorCode = 0;
try
{
errorCode = Integer.parseInt(httpReponse.substring(9, 12));
}
catch (NumberFormatException ignore)
{
throw new IOException("The proxy did not send back a valid HTTP response.");
}
if ((errorCode < 0) || (errorCode > 999))
{
throw new IOException("The proxy did not send back a valid HTTP response.");
}
if (errorCode != 200)
{
throw new HTTPProxyException(httpReponse.substring(13), errorCode);
}
/* OK, read until empty line */
while (true)
{
len = ClientServerHello.readLineRN(in, buffer);
if (len == 0)
{
break;
}
}
return s;
}
throw new IOException("Unsupported ProxyData");
}
private void startReceiver() throws IOException
{
receiveThread = new Thread(new Runnable()
{
public void run()
{
try
{
receiveLoop();
}
catch (Exception e)
{
close(e, false);
log.warning("Receive thread: error in receiveLoop: " + e.getMessage());
}
if (log.isDebugEnabled())
{
log.debug("Receive thread: back from receiveLoop");
}
/* Tell all handlers that it is time to say goodbye */
if (km != null)
{
try
{
km.handleMessage(null, 0);
}
catch (IOException ignored)
{
}
}
for (HandlerEntry he : messageHandlers)
{
try
{
he.mh.handleMessage(null, 0);
}
catch (Exception ignore)
{
}
}
}
});
receiveThread.setDaemon(true);
receiveThread.start();
}
public void clientInit(String hostname, int port, String softwareversion, CryptoWishList cwl,
ServerHostKeyVerifier verifier, DHGexParameters dhgex, int connectTimeout, SecureRandom rnd,
ProxyData proxyData) throws IOException
{
/* First, establish the TCP connection to the SSH-2 server */
sock = establishConnection(hostname, port, proxyData, connectTimeout);
/* Parse the server line and say hello - important: this information is later needed for the
* key exchange (to stop man-in-the-middle attacks) - that is why we wrap it into an object
* for later use.
*/
ClientServerHello csh = ClientServerHello.clientHello(softwareversion, sock.getInputStream(),
sock.getOutputStream());
tc = new TransportConnection(sock.getInputStream(), sock.getOutputStream(), rnd);
km = new ClientKexManager(this, csh, cwl, hostname, port, verifier, rnd);
km.initiateKEX(cwl, dhgex, null, null);
startReceiver();
}
public void serverInit(ServerConnectionState state) throws IOException
{
/* TCP connection is already established */
this.sock = state.s;
/* Parse the client line and say hello - important: this information is later needed for the
* key exchange (to stop man-in-the-middle attacks) - that is why we wrap it into an object
* for later use.
*/
state.csh = ClientServerHello.serverHello(state.softwareversion, sock.getInputStream(), sock.getOutputStream());
tc = new TransportConnection(sock.getInputStream(), sock.getOutputStream(), state.generator);
km = new ServerKexManager(state);
km.initiateKEX(state.next_cryptoWishList, null, state.next_dsa_key, state.next_rsa_key);
startReceiver();
}
public void registerMessageHandler(MessageHandler mh, int low, int high)
{
HandlerEntry he = new HandlerEntry();
he.mh = mh;
he.low = low;
he.high = high;
synchronized (messageHandlers)
{
messageHandlers.add(he);
}
}
public void removeMessageHandler(MessageHandler mh, int low, int high)
{
synchronized (messageHandlers)
{
for (int i = 0; i < messageHandlers.size(); i++)
{
HandlerEntry he = messageHandlers.get(i);
if ((he.mh == mh) && (he.low == low) && (he.high == high))
{
messageHandlers.remove(i);
break;
}
}
}
}
public void sendKexMessage(byte[] msg) throws IOException
{
synchronized (connectionSemaphore)
{
if (connectionClosed)
{
throw (IOException) new IOException("Sorry, this connection is closed.").initCause(reasonClosedCause);
}
flagKexOngoing = true;
try
{
tc.sendMessage(msg);
}
catch (IOException e)
{
close(e, false);
throw e;
}
}
}
public void kexFinished() throws IOException
{
synchronized (connectionSemaphore)
{
flagKexOngoing = false;
connectionSemaphore.notifyAll();
}
}
/**
*
* @param cwl
* @param dhgex
* @param dsa may be null if this is a client connection
* @param rsa may be null if this is a client connection
* @throws IOException
*/
public void forceKeyExchange(CryptoWishList cwl, DHGexParameters dhgex, DSAPrivateKey dsa, RSAPrivateKey rsa)
throws IOException
{
synchronized (connectionSemaphore)
{
if (connectionClosed)
/* Inform the caller that there is no point in triggering a new kex */
throw (IOException) new IOException("Sorry, this connection is closed.").initCause(reasonClosedCause);
}
km.initiateKEX(cwl, dhgex, dsa, rsa);
}
public void changeRecvCipher(BlockCipher bc, MAC mac)
{
tc.changeRecvCipher(bc, mac);
}
public void changeSendCipher(BlockCipher bc, MAC mac)
{
tc.changeSendCipher(bc, mac);
}
public void sendAsynchronousMessage(byte[] msg) throws IOException
{
sendAsynchronousMessage(msg, null);
}
public void sendAsynchronousMessage(byte[] msg, Runnable run) throws IOException
{
synchronized (asynchronousQueue)
{
asynchronousQueue.add(new AsynchronousEntry(msg, run));
asynchronousPending = true;
/* This limit should be flexible enough. We need this, otherwise the peer
* can flood us with global requests (and other stuff where we have to reply
* with an asynchronous message) and (if the server just sends data and does not
* read what we send) this will probably put us in a low memory situation
* (our send queue would grow and grow and...) */
if (asynchronousQueue.size() > 100)
{
throw new IOException("Error: the peer is not consuming our asynchronous replies.");
}
/* Check if we have an asynchronous sending thread */
if (asynchronousThread == null)
{
asynchronousThread = new AsynchronousWorker();
asynchronousThread.setDaemon(true);
asynchronousThread.start();
/* The thread will stop after 2 seconds of inactivity (i.e., empty queue) */
}
asynchronousQueue.notifyAll();
}
}
public void setConnectionMonitors(List monitors)
{
synchronized (this)
{
connectionMonitors = new Vector();
connectionMonitors.addAll(monitors);
}
}
/**
* True if no response message expected.
*/
private boolean idle;
/**
* Send a message but ensure that all queued messages are being sent first.
*
* @param msg
* @throws IOException
*/
public void sendMessage(byte[] msg) throws IOException
{
synchronized (asynchronousQueue)
{
while (asynchronousPending)
{
try
{
asynchronousQueue.wait(1000);
}
catch (InterruptedException e)
{
}
}
}
sendMessageImmediate(msg);
}
/**
* Send message, ignore queued async messages that have not been delivered yet.
* Will be called directly from the asynchronousThread thread.
*
* @param msg
* @throws IOException
*/
public void sendMessageImmediate(byte[] msg) throws IOException
{
if (Thread.currentThread() == receiveThread)
{
throw new IOException("Assertion error: sendMessage may never be invoked by the receiver thread!");
}
boolean wasInterrupted = false;
try
{
synchronized (connectionSemaphore)
{
while (true)
{
if (connectionClosed)
{
throw (IOException) new IOException("Sorry, this connection is closed.")
.initCause(reasonClosedCause);
}
if (flagKexOngoing == false)
{
break;
}
try
{
connectionSemaphore.wait();
}
catch (InterruptedException e)
{
wasInterrupted = true;
}
}
try
{
tc.sendMessage(msg);
idle = false;
}
catch (IOException e)
{
close(e, false);
throw e;
}
}
}
finally
{
if (wasInterrupted)
Thread.currentThread().interrupt();
}
}
public void receiveLoop() throws IOException
{
byte[] msg = new byte[35000];
while (true)
{
int msglen;
try
{
msglen = tc.receiveMessage(msg, 0, msg.length);
}
catch (SocketTimeoutException e)
{
// Timeout in read
if (idle)
{
log.debug("Ignoring socket timeout");
continue;
}
throw e;
}
idle = true;
int type = msg[0] & 0xff;
if (type == Packets.SSH_MSG_IGNORE)
{
continue;
}
if (type == Packets.SSH_MSG_DEBUG)
{
if (log.isDebugEnabled())
{
TypesReader tr = new TypesReader(msg, 0, msglen);
tr.readByte();
tr.readBoolean();
StringBuilder debugMessageBuffer = new StringBuilder();
debugMessageBuffer.append(tr.readString("UTF-8"));
for (int i = 0; i < debugMessageBuffer.length(); i++)
{
char c = debugMessageBuffer.charAt(i);
if ((c >= 32) && (c <= 126))
{
continue;
}
debugMessageBuffer.setCharAt(i, '\uFFFD');
}
log.debug("DEBUG Message from remote: '" + debugMessageBuffer.toString() + "'");
}
continue;
}
if (type == Packets.SSH_MSG_UNIMPLEMENTED)
{
throw new IOException("Peer sent UNIMPLEMENTED message, that should not happen.");
}
if (type == Packets.SSH_MSG_DISCONNECT)
{
TypesReader tr = new TypesReader(msg, 0, msglen);
tr.readByte();
int reason_code = tr.readUINT32();
StringBuilder reasonBuffer = new StringBuilder();
reasonBuffer.append(tr.readString("UTF-8"));
/*
* Do not get fooled by servers that send abnormal long error
* messages
*/
if (reasonBuffer.length() > 255)
{
reasonBuffer.setLength(255);
reasonBuffer.setCharAt(254, '.');
reasonBuffer.setCharAt(253, '.');
reasonBuffer.setCharAt(252, '.');
}
/*
* Also, check that the server did not send characters that may
* screw up the receiver -> restrict to reasonable US-ASCII
* subset -> "printable characters" (ASCII 32 - 126). Replace
* all others with 0xFFFD (UNICODE replacement character).
*/
for (int i = 0; i < reasonBuffer.length(); i++)
{
char c = reasonBuffer.charAt(i);
if ((c >= 32) && (c <= 126))
{
continue;
}
reasonBuffer.setCharAt(i, '\uFFFD');
}
throw new IOException("Peer sent DISCONNECT message (reason code " + reason_code + "): "
+ reasonBuffer.toString());
}
/*
* Is it a KEX Packet?
*/
if ((type == Packets.SSH_MSG_KEXINIT) || (type == Packets.SSH_MSG_NEWKEYS)
|| ((type >= 30) && (type <= 49)))
{
km.handleMessage(msg, msglen);
continue;
}
MessageHandler mh = null;
for (int i = 0; i < messageHandlers.size(); i++)
{
HandlerEntry he = messageHandlers.get(i);
if ((he.low <= type) && (type <= he.high))
{
mh = he.mh;
break;
}
}
if (mh == null)
{
throw new IOException("Unexpected SSH message (type " + type + ")");
}
mh.handleMessage(msg, msglen);
}
}
}
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