Visual Basic 6.0

Check Whether SSH Channel CLOSE Was Received

Demonstrates the Chilkat Ssh.ChannelReceivedClose method, which reports whether an SSH CLOSE message has been received for a channel. The only argument is the channel number. Remote CLOSE is distinct from EOF and closes the channel in both directions.

Background: Remote CLOSE is the definitive end of a channel's life. Once it is processed, ChannelIsOpen becomes false and the channel is normally removed from NumOpenChannels. Checking it distinguishes "the server finished sending output" (EOF) from "the channel is fully finished" (CLOSE) — which is what you want before concluding a remote command has completely wrapped up.

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Visual Basic 6.0

Dim success As Long
success = 0

'  Demonstrates the Ssh.ChannelReceivedClose method, which reports whether an SSH CLOSE message
'  has been received for a channel.  The only argument is the channel number.  Remote CLOSE is
'  distinct from EOF and closes the channel in both directions.

Dim ssh As New ChilkatSsh

Dim sshPort As Long
sshPort = 22
success = ssh.Connect("ssh.example.com",sshPort)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
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.
Dim password As String
password = "mySshPassword"

success = ssh.AuthenticatePw("mySshLogin",password)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

Dim channelNum As Long
channelNum = ssh.OpenSessionChannel()
If (channelNum < 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

success = ssh.SendReqExec(channelNum,"ls -l /tmp")
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  IMPORTANT: Set a read timeout.  ReadTimeoutMs defaults to 0, which means no limit -- without
'  it, this call waits forever if the server never sends channel close.
ssh.ReadTimeoutMs = 15000

success = ssh.ChannelReceiveToClose(channelNum)
If (success = 0) Then
    Debug.Print ssh.LastErrorText
    Exit Sub
End If

'  The server may send EOF before CLOSE.  During that interval EOF is 1 while CLOSE is
'  still 0.
If (ssh.ChannelReceivedEof(channelNum)) Then
    Debug.Print "EOF received."
End If

If (ssh.ChannelReceivedClose(channelNum)) Then
    Debug.Print "Remote CLOSE received -- the channel is closed in both directions."
Else
    Debug.Print "No remote CLOSE received."
End If

ssh.Disconnect