Classic ASP

Receive from an SSH Channel Until a Pattern Matches

Demonstrates the Chilkat Ssh.ChannelReceiveUntilMatch method, which receives text until the accumulated text matches a pattern. The arguments are the channel number, the pattern, the charset, and whether matching is case-sensitive. Existing buffered text is checked before waiting for more network data.

Important: Set the ReadTimeoutMs property before calling this method. It defaults to 0, meaning no limit, so without it the call waits forever if the received data never contains a match.

Background: Driving a shell channel means knowing when the remote side has finished talking. With no PTY requested the shell is non-interactive and never prints a prompt, so the reliable signal is a marker you deliberately echo after your command. This method automates "read until you see X." The pattern syntax is deliberately minimal: literal characters plus *, which matches zero or more characters and can span line breaks. ? and bracket classes are not supported, and backslash does not escape a literal *.

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<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
</head>
<body>
<%
success = 0

'  Demonstrates the Ssh.ChannelReceiveUntilMatch method, which receives text until the
'  accumulated text matches a pattern.  The 1st argument is the channel number, the 2nd is the
'  pattern, the 3rd is the charset, and the 4th selects case-sensitive matching.  The pattern
'  supports literal characters plus "*", which matches zero or more characters.

set ssh = Server.CreateObject("Chilkat.Ssh")

sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

'  Normally you would not hard-code the password in source.  You should instead obtain it
'  from an interactive prompt, environment variable, or a secrets vault.
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

channelNum = ssh.OpenSessionChannel()
If (channelNum < 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

'  Start a shell WITHOUT requesting a PTY.  Without a PTY the shell sees it is connected to a
'  raw data pipe and enters non-interactive mode: it suppresses the command prompt, does not
'  echo typed commands back, and skips interactive login scripts.  The output is therefore
'  clean and easily parseable -- but because no prompt is ever sent, code must not wait for
'  one.  Instead, have each command print a predictable marker, or wait for EOF / channel close.
success = ssh.SendReqShell(channelNum)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

'  There is no prompt to wait for, so make the command itself announce when it has finished
'  by echoing a marker after it.
success = ssh.ChannelSendString(channelNum,"ls -l /tmp; echo DONE_MARKER" & vbLf,"utf-8")
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

'  IMPORTANT: Set a read timeout before receiving until a match.  ReadTimeoutMs defaults to 0,
'  which means no limit -- without it, this call waits forever if the received data never
'  contains a match.
ssh.ReadTimeoutMs = 15000

'  Receive until the marker appears in the output.
caseSensitive = 0
success = ssh.ChannelReceiveUntilMatch(channelNum,"DONE_MARKER","utf-8",caseSensitive)
If (success = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

output = ssh.GetReceivedText(channelNum,"utf-8")
If (ssh.LastMethodSuccess = 0) Then
    Response.Write "<pre>" & Server.HTMLEncode( ssh.LastErrorText) & "</pre>"
    Response.End
End If

Response.Write "<pre>" & Server.HTMLEncode( output) & "</pre>"

ssh.Disconnect 

%>
</body>
</html>