Hi ymnk,
I have found a timing issue with reverse port forwarding
(session.setPortForwardingR). This is affecting my application when it
is running on the same physical box as the SSH server. My application
sets up a series of remote forwards, and I noticed that calls to
session.setPortForwardingR() take a very long time (exactly 10 seconds
to be precise). This is because the reply from the SSH server is being
received before the sending thread is ready (sleeping). So, the thread
interrupt never occurs, and the sending thread sleeps for the full 10
seconds.
I have resolved the issue by replacing the sleep/interrupt logic with a
simple synchronized reply lock. I have attached the patch diffs to
0.1.43 below.
Thanks.
- Scott
P.S: Please also notice that I will throw the error Exception with
(reply!=1) as opposed to (reply==0) because reply is seeded to -1, and
if the reply is not received within the full 10 seconds window, I think
we still want to throw the error.
==== Begin Patch ====
*** Session.java version 0.1.43
--- Session.java patched
***************
*** 1503,1512 ****
break;
case SSH_MSG_REQUEST_FAILURE:
case SSH_MSG_REQUEST_SUCCESS:
Thread t=grr.getThread();
if(t!=null){
grr.setReply(msgType==SSH_MSG_REQUEST_SUCCESS? 1 : 0);
! t.interrupt();
}
break;
default:
--- 1503,1514 ----
break;
case SSH_MSG_REQUEST_FAILURE:
case SSH_MSG_REQUEST_SUCCESS:
+ synchronized(grr.replyLock){
Thread t=grr.getThread();
if(t!=null){
grr.setReply(msgType==SSH_MSG_REQUEST_SUCCESS? 1 : 0);
! grr.replyLock.notifyAll();
! }
}
break;
default:
***************
*** 1657,1662 ****
--- 1659,1665 ----
private class GlobalRequestReply{
private Thread thread=null;
private int reply=-1;
+ public Object replyLock = new Object();
void setThread(Thread thread){
this.thread=thread;
this.reply=-1;
***************
*** 1673,1678 ****
--- 1676,1682 ----
String address_to_bind=ChannelForwardedTCPIP.normalize(bind_address);
+ synchronized(grr.replyLock){
try{
// byte SSH_MSG_GLOBAL_REQUEST 80
// string "tcpip-forward"
***************
*** 1695,1709 ****
}
grr.setThread(Thread.currentThread());
! try{ Thread.sleep(10000);}
! catch(Exception e){
}
int reply=grr.getReply();
grr.setThread(null);
! if(reply==0){
throw new JSchException("remote port forwarding failed for
listen port "+rport);
}
}
}
public void delPortForwardingR(int rport) throws JSchException{
ChannelForwardedTCPIP.delPort(this, rport);
--- 1699,1714 ----
}
grr.setThread(Thread.currentThread());
! try{ grr.replyLock.wait(10000); }
! catch(InterruptedException e){
}
int reply=grr.getReply();
grr.setThread(null);
! if(reply!=1){
throw new JSchException("remote port forwarding failed for
listen port "+rport);
}
}
+ }
}
public void delPortForwardingR(int rport) throws JSchException{
ChannelForwardedTCPIP.delPort(this, rport);
==== End Patch ====
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