diff options
Diffstat (limited to 'sshlib/src/main/java/com/trilead/ssh2/channel/RemoteX11AcceptThread.java')
| -rw-r--r-- | sshlib/src/main/java/com/trilead/ssh2/channel/RemoteX11AcceptThread.java | 240 |
1 files changed, 240 insertions, 0 deletions
diff --git a/sshlib/src/main/java/com/trilead/ssh2/channel/RemoteX11AcceptThread.java b/sshlib/src/main/java/com/trilead/ssh2/channel/RemoteX11AcceptThread.java new file mode 100644 index 0000000..9f99410 --- /dev/null +++ b/sshlib/src/main/java/com/trilead/ssh2/channel/RemoteX11AcceptThread.java @@ -0,0 +1,240 @@ + +package com.trilead.ssh2.channel; + +import java.io.IOException; +import java.io.InputStream; +import java.io.OutputStream; +import java.net.Socket; + +import com.trilead.ssh2.log.Logger; + + +/** + * RemoteX11AcceptThread. + * + * @author Christian Plattner, plattner@trilead.com + * @version $Id: RemoteX11AcceptThread.java,v 1.2 2008/04/01 12:38:09 cplattne Exp $ + */ +public class RemoteX11AcceptThread extends Thread +{ + private static final Logger log = Logger.getLogger(RemoteX11AcceptThread.class); + + Channel c; + + String remoteOriginatorAddress; + int remoteOriginatorPort; + + Socket s; + + public RemoteX11AcceptThread(Channel c, String remoteOriginatorAddress, int remoteOriginatorPort) + { + this.c = c; + this.remoteOriginatorAddress = remoteOriginatorAddress; + this.remoteOriginatorPort = remoteOriginatorPort; + } + + public void run() + { + try + { + /* Send Open Confirmation */ + + c.cm.sendOpenConfirmation(c); + + /* Read startup packet from client */ + + OutputStream remote_os = c.getStdinStream(); + InputStream remote_is = c.getStdoutStream(); + + /* The following code is based on the protocol description given in: + * Scheifler/Gettys, + * X Windows System: Core and Extension Protocols: + * X Version 11, Releases 6 and 6.1 ISBN 1-55558-148-X + */ + + /* + * Client startup: + * + * 1 0X42 MSB first/0x6c lSB first - byteorder + * 1 - unused + * 2 card16 - protocol-major-version + * 2 card16 - protocol-minor-version + * 2 n - lenght of authorization-protocol-name + * 2 d - lenght of authorization-protocol-data + * 2 - unused + * string8 - authorization-protocol-name + * p - unused, p=pad(n) + * string8 - authorization-protocol-data + * q - unused, q=pad(d) + * + * pad(X) = (4 - (X mod 4)) mod 4 + * + * Server response: + * + * 1 (0 failed, 2 authenticate, 1 success) + * ... + * + */ + + /* Later on we will simply forward the first 6 header bytes to the "real" X11 server */ + + byte[] header = new byte[6]; + + if (remote_is.read(header) != 6) + throw new IOException("Unexpected EOF on X11 startup!"); + + if ((header[0] != 0x42) && (header[0] != 0x6c)) // 0x42 MSB first, 0x6C LSB first + throw new IOException("Unknown endian format in X11 message!"); + + /* Yes, I came up with this myself - shall I file an application for a patent? =) */ + + int idxMSB = (header[0] == 0x42) ? 0 : 1; + + /* Read authorization data header */ + + byte[] auth_buff = new byte[6]; + + if (remote_is.read(auth_buff) != 6) + throw new IOException("Unexpected EOF on X11 startup!"); + + int authProtocolNameLength = ((auth_buff[idxMSB] & 0xff) << 8) | (auth_buff[1 - idxMSB] & 0xff); + int authProtocolDataLength = ((auth_buff[2 + idxMSB] & 0xff) << 8) | (auth_buff[3 - idxMSB] & 0xff); + + if ((authProtocolNameLength > 256) || (authProtocolDataLength > 256)) + throw new IOException("Buggy X11 authorization data"); + + int authProtocolNamePadding = ((4 - (authProtocolNameLength % 4)) % 4); + int authProtocolDataPadding = ((4 - (authProtocolDataLength % 4)) % 4); + + byte[] authProtocolName = new byte[authProtocolNameLength]; + byte[] authProtocolData = new byte[authProtocolDataLength]; + + byte[] paddingBuffer = new byte[4]; + + if (remote_is.read(authProtocolName) != authProtocolNameLength) + throw new IOException("Unexpected EOF on X11 startup! (authProtocolName)"); + + if (remote_is.read(paddingBuffer, 0, authProtocolNamePadding) != authProtocolNamePadding) + throw new IOException("Unexpected EOF on X11 startup! (authProtocolNamePadding)"); + + if (remote_is.read(authProtocolData) != authProtocolDataLength) + throw new IOException("Unexpected EOF on X11 startup! (authProtocolData)"); + + if (remote_is.read(paddingBuffer, 0, authProtocolDataPadding) != authProtocolDataPadding) + throw new IOException("Unexpected EOF on X11 startup! (authProtocolDataPadding)"); + + if ("MIT-MAGIC-COOKIE-1".equals(new String(authProtocolName, "ISO-8859-1")) == false) + throw new IOException("Unknown X11 authorization protocol!"); + + if (authProtocolDataLength != 16) + throw new IOException("Wrong data length for X11 authorization data!"); + + StringBuffer tmp = new StringBuffer(32); + for (int i = 0; i < authProtocolData.length; i++) + { + String digit2 = Integer.toHexString(authProtocolData[i] & 0xff); + tmp.append((digit2.length() == 2) ? digit2 : "0" + digit2); + } + String hexEncodedFakeCookie = tmp.toString(); + + /* Order is very important here - it may be that a certain x11 forwarding + * gets disabled right in the moment when we check and register our connection + * */ + + synchronized (c) + { + /* Please read the comment in Channel.java */ + c.hexX11FakeCookie = hexEncodedFakeCookie; + } + + /* Now check our fake cookie directory to see if we produced this cookie */ + + X11ServerData sd = c.cm.checkX11Cookie(hexEncodedFakeCookie); + + if (sd == null) + throw new IOException("Invalid X11 cookie received."); + + /* If the session which corresponds to this cookie is closed then we will + * detect this: the session's close code will close all channels + * with the session's assigned x11 fake cookie. + */ + + s = new Socket(sd.hostname, sd.port); + + OutputStream x11_os = s.getOutputStream(); + InputStream x11_is = s.getInputStream(); + + /* Now we are sending the startup packet to the real X11 server */ + + x11_os.write(header); + + if (sd.x11_magic_cookie == null) + { + byte[] emptyAuthData = new byte[6]; + /* empty auth data, hopefully you are connecting to localhost =) */ + x11_os.write(emptyAuthData); + } + else + { + if (sd.x11_magic_cookie.length != 16) + throw new IOException("The real X11 cookie has an invalid length!"); + + /* send X11 cookie specified by client */ + x11_os.write(auth_buff); + x11_os.write(authProtocolName); /* re-use */ + x11_os.write(paddingBuffer, 0, authProtocolNamePadding); + x11_os.write(sd.x11_magic_cookie); + x11_os.write(paddingBuffer, 0, authProtocolDataPadding); + } + + x11_os.flush(); + + /* Start forwarding traffic */ + + StreamForwarder r2l = new StreamForwarder(c, null, s, remote_is, x11_os, "RemoteToX11"); + StreamForwarder l2r = new StreamForwarder(c, null, null, x11_is, remote_os, "X11ToRemote"); + + /* No need to start two threads, one can be executed in the current thread */ + + r2l.setDaemon(true); + r2l.start(); + l2r.run(); + + while (r2l.isAlive()) + { + try + { + r2l.join(); + } + catch (InterruptedException e) + { + } + } + + /* If the channel is already closed, then this is a no-op */ + + c.cm.closeChannel(c, "EOF on both X11 streams reached.", true); + s.close(); + } + catch (IOException e) + { + log.log(50, "IOException in X11 proxy code: " + e.getMessage()); + + try + { + c.cm.closeChannel(c, "IOException in X11 proxy code (" + e.getMessage() + ")", true); + } + catch (IOException e1) + { + } + try + { + if (s != null) + s.close(); + } + catch (IOException e1) + { + } + } + } +} |