DataFlex

Wait for a Message on Any SSH Channel

Demonstrates the Chilkat Ssh.WaitForChannelMessage method, which waits for the next SSH channel message on any channel. The only argument is the poll timeout: 0 for a nonblocking check, a positive value to wait that long, or a negative value to wait with no method-level timeout. It returns the channel number the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error such as a lost connection.

Background: When several channels are active at once, waiting on one specific channel would block while others sit ready. This method is the multiplexed alternative — it returns as soon as any channel has activity and tells you which one, so a single loop can service them all. The explicit timeout argument governs the wait; shorter ReadTimeoutMs values do not cut it short.

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DataFlex

Use ChilkatAx-win32.pkg

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

    Move False To iSuccess

    //  Demonstrates the Ssh.WaitForChannelMessage method, which waits for the next SSH channel
    //  message on ANY channel.  The only argument is the poll timeout in milliseconds: 0 for a
    //  nonblocking check, a positive value to wait that long, or a negative value to wait with no
    //  method-level timeout.

    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

    Get ComOpenSessionChannel Of hoSsh To iChannelNum
    If (iChannelNum < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComSendReqExec Of hoSsh iChannelNum "ls -l /tmp" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Wait up to 5 seconds for the next channel message.  The return value is the channel number
    //  the message belongs to, -1 if nothing arrived before the timeout, or -2 on another error.
    Move 5000 To iPollTimeoutMs
    Get ComWaitForChannelMessage Of hoSsh iPollTimeoutMs To iResult

    If (iResult = -2) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    If (iResult = -1) Begin
        Showln "No channel message arrived before the timeout."
    End

    If (iResult >= 0) Begin
        Showln "Processed a message for channel " iResult
    End

    Send ComDisconnect To hoSsh


End_Procedure