Poll an SSH Channel for Incoming Data

See more SSH Examples

Demonstrates the Chilkat Ssh.ChannelPoll method, which polls a channel for incoming messages, waiting at most the given number of milliseconds. The first argument is the channel number and the second is the poll timeout; pass 0 for a nonblocking poll.

The integer return value is -1 on error, -2 if nothing arrived before the timeout, 0 if EOF or channel close was processed, or — when greater than 0 — the total bytes currently buffered for the channel (not the bytes newly received by this call).

-- Important: See this note about string length limitations for strings returned by sp_OAMethod calls.
--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @iTmp0 int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  Demonstrates the Ssh.ChannelPoll method, which polls a channel for incoming messages, waiting
    --  at most the given number of milliseconds.  The 1st argument is the channel number and the 2nd
    --  is the poll timeout.  Pass 0 for a nonblocking poll.

    DECLARE @ssh int
    EXEC @hr = sp_OACreate 'Chilkat.Ssh', @ssh OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    DECLARE @sshPort int
    SELECT @sshPort = 22
    EXEC sp_OAMethod @ssh, 'Connect', @success OUT, 'ssh.example.com', @sshPort
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        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.
    DECLARE @password nvarchar(4000)
    SELECT @password = 'mySshPassword'

    EXEC sp_OAMethod @ssh, 'AuthenticatePw', @success OUT, 'mySshLogin', @password
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    DECLARE @channelNum int
    EXEC sp_OAMethod @ssh, 'OpenSessionChannel', @channelNum OUT
    IF @channelNum < 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  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.
    EXEC sp_OAMethod @ssh, 'SendReqShell', @success OUT, @channelNum
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    EXEC sp_OAMethod @ssh, 'ChannelSendString', @success OUT, @channelNum, 'date' + CHAR(10), 'utf-8'
    IF @success = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    --  Wait up to 3 seconds for channel data.
    DECLARE @pollTimeoutMs int
    SELECT @pollTimeoutMs = 3000
    --  The return value is: -1 on error, -2 if nothing arrived before the timeout, 0 if EOF or
    --  channel close was processed, or the total number of buffered bytes when greater than 0.
    DECLARE @result int
    EXEC sp_OAMethod @ssh, 'ChannelPoll', @result OUT, @channelNum, @pollTimeoutMs
    IF @result = -1
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    IF @result = -2
      BEGIN

        PRINT 'No channel data arrived before the timeout.'
      END

    IF @result = 0
      BEGIN

        PRINT 'EOF or channel close was processed.  Buffered data may still remain.'
      END

    IF @result > 0
      BEGIN

        PRINT 'Total bytes buffered: ' + @result
      END

    DECLARE @output nvarchar(4000)
    EXEC sp_OAMethod @ssh, 'GetReceivedText', @output OUT, @channelNum, 'utf-8'
    EXEC sp_OAGetProperty @ssh, 'LastMethodSuccess', @iTmp0 OUT
    IF @iTmp0 = 0
      BEGIN
        EXEC sp_OAGetProperty @ssh, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @ssh
        RETURN
      END

    PRINT @output

    EXEC sp_OAMethod @ssh, 'Disconnect', NULL

    EXEC @hr = sp_OADestroy @ssh


END
GO