DataFlex

Check Whether an SSH Channel is Open

Demonstrates the Chilkat Ssh.ChannelIsOpen method, which reports whether a channel number identifies a channel Chilkat currently considers open for application I/O. The only argument is the channel number. This example checks the channel before and after sending CLOSE.

Background: Because one SSH connection can carry many channels with independent lifetimes, code that manages several needs a way to ask whether a given one is still usable. This returns false for invalid or nonexistent channel numbers, after a local Disconnect, once remote closure is processed, and immediately after ChannelSendClose — which marks the channel locally closed without waiting for the remote side.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSsh
    Integer iSshPort
    String sPassword
    Integer iChannelNum
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  Demonstrates the Ssh.ChannelIsOpen method, which reports whether a channel number identifies
    //  a channel Chilkat currently considers open for application I/O.  The only argument is the
    //  channel number.

    Get Create (RefClass(cComChilkatSsh)) To hoSsh
    If (Not(IsComObjectCreated(hoSsh))) Begin
        Send CreateComObject of hoSsh
    End

    Move 22 To iSshPort
    Get ComConnect Of hoSsh "ssh.example.com" iSshPort To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Move "mySshPassword" To sPassword

    Get ComAuthenticatePw Of hoSsh "mySshLogin" sPassword To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Open a session channel.  A negative return value indicates failure.
    Get ComOpenSessionChannel Of hoSsh To iChannelNum
    If (iChannelNum < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComChannelIsOpen Of hoSsh iChannelNum To bTemp1
    If (bTemp1) Begin
        Showln "The channel is open."
    End
    Else Begin
        Showln "The channel is not open."
    End

    //  Send CLOSE, which immediately marks the channel locally closed.
    Get ComChannelSendClose Of hoSsh iChannelNum To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComChannelIsOpen Of hoSsh iChannelNum To bTemp1
    If (bTemp1) Begin
        Showln "Still open."
    End
    Else Begin
        Showln "The channel is now closed."
    End

    Send ComDisconnect To hoSsh


End_Procedure