Tcl

Abort a Running SSH Tunnel Operation

Demonstrates the AbortCurrent property, which requests that the currently running foreground operation be aborted. It is intended to be set to true from another thread — for example, to interrupt a synchronous Connect that is waiting for an unresponsive server.

Background: A synchronous call like Connect blocks the calling thread until it finishes or times out, which is a problem when a user clicks "Cancel" or the app needs to shut down. Setting AbortCurrent from a different thread breaks the blocked operation out early, returning a failure the caller can handle. Note its scope is deliberately limited to the current foreground operation: it does not stop the background listener or terminate established tunnel clients — use StopAccepting or CloseTunnel for those.

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Tcl


load ./chilkat.dll

set success 0

#  Demonstrates the SshTunnel.AbortCurrent property, which requests that the currently running
#  foreground operation be aborted.

set tunnel [new_CkSshTunnel]

#  AbortCurrent is intended to be set to 1 from ANOTHER thread to interrupt a synchronous
#  operation in progress -- for example, a Connect that is waiting for an unresponsive server.
#  It does not stop the background listener or terminate established background tunnel clients.
#  
#  The assignment below illustrates the property.  In a real application it would be set on a
#  separate thread while Connect blocks; if it becomes 1, the blocked Connect returns with a
#  failure.
CkSshTunnel_put_AbortCurrent $tunnel 0

CkSshTunnel_put_DestHostname $tunnel "db.internal.example.com"
CkSshTunnel_put_DestPort $tunnel 5432

set sshPort 22
set success [CkSshTunnel_Connect $tunnel "ssh.example.com" $sshPort]
if {$success == 0} then {
    puts [CkSshTunnel_lastErrorText $tunnel]
    delete_CkSshTunnel $tunnel
    exit
}

puts "Connected."

set waitForThreadExit 1
set success [CkSshTunnel_CloseTunnel $tunnel $waitForThreadExit]
if {$success == 0} then {
    puts [CkSshTunnel_lastErrorText $tunnel]
    delete_CkSshTunnel $tunnel
    exit
}


delete_CkSshTunnel $tunnel