DataFlex

SSH to a Cisco Switch - Processing "More" Responses

Demonstrates connecting to a Cisco switch, entering privileged mode with the ena command, and running a command whose response is paged. Each page ends with --More-- and requires a SPACE character to request the next page.

Note: QuickShell allocates a PTY, which is what a network device console expects. The device presents an interactive prompt, and each command's output is read up to the next prompt.

Background: Paged output is the console equivalent of a pager like more, and a client must reproduce the keypress a human would make. Matching a set of patterns is what makes this tractable: each read ends either at the device prompt (output complete) or at --More-- (another page waiting), and the code branches accordingly. Note the prompt pattern includes the device name rather than a bare #, because that character also appears inside configuration text and would otherwise match far too early.

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DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSsh
    Integer iPort
    String sPassword
    Integer iChannelNum
    Boolean iCaseSensitive
    String sReceived
    String sEnablePassword
    Variant vSaMatch
    Handle hoSaMatch
    Handle hoSbReceived
    Boolean iMoreComing
    String sPageText
    String sTemp1
    Boolean bTemp1

    Move False To iSuccess

    //  This example requires the Chilkat API to have been previously unlocked.
    //  See Global Unlock Sample for sample code.

    //  Demonstrates connecting to a Cisco switch, entering privileged mode, and running a command
    //  whose response is paged -- each page ends with "--More--" and requires a SPACE character to
    //  request the next page.

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

    Move 22 To iPort
    Get ComConnect Of hoSsh "172.16.16.100" iPort 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 ComQuickShell Of hoSsh To iChannelNum
    If (iChannelNum < 0) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  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.
    Set ComReadTimeoutMs Of hoSsh To 15000

    Move True To iCaseSensitive

    //  In unprivileged mode the switch prompt ends with ">".
    Get ComChannelReceiveUntilMatch Of hoSsh iChannelNum ">" "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sReceived
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sReceived

    //  Send "ena" to enter privileged mode.  Cisco devices expect a bare CR to terminate a command.
    Get ComChannelSendString Of hoSsh iChannelNum "ena" + (character(13)) "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComChannelReceiveUntilMatch Of hoSsh iChannelNum "Password:" "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sReceived
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sReceived

    //  The enable password is separate from the login password, and likewise should come from a
    //  secure source rather than being hard-coded.
    Move "myEnablePassword" To sEnablePassword
    Get ComChannelSendString Of hoSsh iChannelNum sEnablePassword "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComChannelSendString Of hoSsh iChannelNum (character(13)) "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  In privileged mode the prompt ends with "#" instead of ">".
    Get ComChannelReceiveUntilMatch Of hoSsh iChannelNum "#" "utf-8" iCaseSensitive To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sReceived
    Get ComLastMethodSuccess Of hoSsh To bTemp1
    If (bTemp1 = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln sReceived

    //  Run a command whose output is delivered a page at a time.
    Get ComChannelSendString Of hoSsh iChannelNum "show running-config" + (character(13)) "utf-8" To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoSsh To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    //  Each read ends either at the device prompt (output complete) or at "--More--" (another page
    //  is waiting).  Match the full prompt rather than a bare "#", because "#" also appears inside
    //  configuration text and would match too early.
    Get Create (RefClass(cComCkStringArray)) To hoSaMatch
    If (Not(IsComObjectCreated(hoSaMatch))) Begin
        Send CreateComObject of hoSaMatch
    End
    Get ComAppend Of hoSaMatch "MySwitchName#" To iSuccess
    Get ComAppend Of hoSaMatch "--More--" To iSuccess

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbReceived
    If (Not(IsComObjectCreated(hoSbReceived))) Begin
        Send CreateComObject of hoSbReceived
    End
    Move True To iMoreComing

    While iMoreComing
        Get pvComObject of hoSaMatch to vSaMatch
        Get ComChannelReceiveUntilMatchN Of hoSsh iChannelNum vSaMatch "utf-8" iCaseSensitive To iSuccess
        If (iSuccess = False) Begin
            Get ComLastErrorText Of hoSsh To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        Send ComClear To hoSbReceived
        Get ComGetReceivedText Of hoSsh iChannelNum "utf-8" To sPageText
        Get ComLastMethodSuccess Of hoSsh To bTemp1
        If (bTemp1 = False) Begin
            Get ComLastErrorText Of hoSsh To sTemp1
            Showln sTemp1
            Procedure_Return
        End

        Get ComAppend Of hoSbReceived sPageText To iSuccess
        Showln sPageText

        //  If this page ended with "--More--", send a SPACE to request the next page.
        Get ComContains Of hoSbReceived "--More--" iCaseSensitive To iMoreComing
        If (iMoreComing) Begin
            Get ComChannelSendString Of hoSsh iChannelNum " " "utf-8" To iSuccess
            If (iSuccess = False) Begin
                Get ComLastErrorText Of hoSsh To sTemp1
                Showln sTemp1
                Procedure_Return
            End

        End

    Loop

    Send ComDisconnect To hoSsh


End_Procedure