Using PLink interactively as a Telnet process with VB.Net 2003

[Guest]

I'm currently attempting to use PLink (the console component of PUTTY - see
http://www.chiark.greenend.org.uk/~sgtatham/putty/) as a Telnet component as
I may in future need to change to using SSH and this seems an ideal solution.
I'm running it as a process and re-directing the standardinput/output/error

However, despite working through all the different variations of code I can
either think of or find I am unable to achieve true interactivity with the
program (which would be nice). I can happily pass commands to the program,
but once it has connected to the Telnet destination (i.e. Once I have passed
the password), I do not get any output returned to standardoutput until PLink
exits, at which point I get it all. I have tried reading the
standardoutput/error on different threads to see if they were blocking the
processing, but this did not seem to be the case, so I dropped back to the
simpler more hackable code you see below.

I have attached the main block below, it's not very neat due to being
reworked multiple times and may now contain some redundant bits so apologies
in advance. Hopefully however it may provide a basis for someone to point out
what I need to change to get this thing working.

Friend Shared TelnetProcess As System.diagnostics.Process = New
System.diagnostics.Process
Friend Shared TelnetStage As Integer = 0
Friend Shared TelnetBuffer As String = ""
Friend Shared TelnetBufferFull As String = ""
Friend Shared TelnetIn As StreamWriter
Friend Shared TelnetOut As StreamReader
Friend Shared TelnetErr As StreamReader
Friend WithEvents tmrProcessAIX As System.Timers.Timer = New
System.Timers.Timer
Friend WithEvents tmrProcessSwitch As System.Timers.Timer = New
System.Timers.Timer
Friend WithEvents objStdOutRead As clsStdOutRead = New clsStdOutRead
Friend WithEvents objStdErrRead As clsStdErrRead = New clsStdErrRead
Friend thrdProcessStdOutRead As Thread = New Thread(AddressOf
objStdOutRead.StdOutRead)
Friend thrdProcessStdErrRead As Thread = New Thread(AddressOf
objStdErrRead.StdErrRead)

Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As
System.EventArgs) Handles Button1.Click

TextBox1.Text = ""

TelnetStage = 0
TelnetBuffer = ""
TelnetBufferFull = ""

TelnetProcess.StartInfo.FileName = Application.StartupPath &
"\tools\" & "plink.exe"
TelnetProcess.StartInfo.Arguments = " -telnet 192.168.1.6 -l myid"
TelnetProcess.StartInfo.UseShellExecute = False
TelnetProcess.StartInfo.CreateNoWindow = True
TelnetProcess.StartInfo.RedirectStandardInput = True
TelnetProcess.StartInfo.RedirectStandardOutput = True
'TelnetProcess.StartInfo.RedirectStandardError = True
TelnetProcess.Start()
TelnetIn = TelnetProcess.StandardInput
TelnetOut = TelnetProcess.StandardOutput
TelnetErr = TelnetProcess.StandardOutput
TelnetProcess.StandardInput.AutoFlush = True
tmrProcess.Interval = 1000
tmrProcess.Enabled = True

End Sub

Sub tmrProcess_Elapsed(ByVal sender As Object, ByVal e As
System.Timers.ElapsedEventArgs) Handles tmrProcessAIX.Elapsed

Dim sOutBuffer As String = ""
Dim x As String
Dim iChar As Integer

Try
Select Case TelnetStage
Case 0
tmrProcessAIX.Enabled = False
Do While TelnetProcess.StandardOutput.Peek() >= 0
iChar = TelnetProcess.StandardOutput.Read()
TelnetBuffer = TelnetBuffer & (Convert.ToChar(iChar))
Console.WriteLine("TB >" & TelnetBuffer.ToString())
Loop
If (InStr(TelnetBuffer, "Password:") > 0) Then
TelnetProcess.StandardInput.Write("password" & vbCrLf)
TelnetBufferFull = TelnetBufferFull & TelnetBuffer &
"xxxxxxxx" & System.Environment.NewLine
TelnetBuffer = ""
TelnetStage = 1
End If
tmrProcessAIX.Enabled = True
Case 1
tmrProcessAIX.Enabled = False
Do While TelnetProcess.StandardOutput.Peek() >= 0
iChar = TelnetProcess.StandardOutput.Read()
TelnetBuffer = TelnetBuffer & (Convert.ToChar(iChar))
Console.WriteLine("TB >" & TelnetBuffer.ToString())
Loop
TelnetProcess.StandardInput.WriteLine("command" & vbCrLf)
TelnetBufferFull = TelnetBufferFull & TelnetBuffer
TelnetBuffer = ""
TelnetStage = 98
tmrProcessAIX.Enabled = True

Case 98
tmrProcessAIX.Enabled = False
Do While TelnetProcess.StandardOutput.Peek() >= 0
iChar = TelnetProcess.StandardOutput.Read()
TelnetBuffer = TelnetBuffer & (Convert.ToChar(iChar))
Console.WriteLine("TB >" & TelnetBuffer.ToString())
Loop
TelnetProcess.StandardInput.WriteLine("exit" & vbCrLf)
TelnetProcess.StandardInput.WriteLine("exit" & vbCrLf)
TelnetBufferFull = TelnetBufferFull & TelnetBuffer
TelnetBuffer = ""
TelnetStage = 99
Console.WriteLine("TBF>" & TelnetBufferFull)
tmrProcessAIX.Enabled = True
Case 99
tmrProcessAIX.Enabled = False
Do While TelnetProcess.StandardOutput.Peek() >= 0
iChar = TelnetProcess.StandardOutput.Read()
TelnetBuffer = TelnetBuffer & (Convert.ToChar(iChar))
Console.WriteLine("TB >" & TelnetBuffer.ToString())
Loop
TelnetBufferFull = TelnetBufferFull & TelnetBuffer
x = TelnetBufferFull &
TelnetProcess.StandardOutput.ReadToEnd
'MsgBox(x)
TextBox1.Text = x
TelnetProcess.Kill()
End Select

Catch ioe As InvalidOperationException
Catch ex As Exception
MsgBox(ex.ToString)
Finally
End Try

End Sub

 

[vglass]

Consider using Telnet Factory for .NET and SSH Factory for .NET
together to obtain both telnet and ssh scripting functionality:

http://www.jscape.com/telnetfactorydotnet/

http://www.jscape.com/sshfactorydotnet/

 

[Guest]

Two points on that :

1. I would prefer not to use a commercial addin component as I have no
budget available for one.

2. Whilst in this instance I'm using PLink, it is likely that I will have
other external console/command-line programs to wrap and therefore I would
like to get the procedure sorted out properly now.

Al
Systems Type

Consider using Telnet Factory for .NET and SSH Factory for .NET
together to obtain both telnet and ssh scripting functionality:

<snip>