FTP appears to be caching(?)

[CharlieH]

Hi,

 

I have written a small script to read a file from an FTP server and check its contents. This can be re-run by the press of a button, however, if the file is deleted from the ftp server between runs (with the .exe still live), the file is still "read" and written locally, which then passes the check.

 

If I run it initially without the file, it correctly fails and pops up my error message, but if the file is then added, it then seemingly gets cached (or similar) so that the app then always reports a success.

 

The below code snippet is just the function run when the "test" button is pressed. It includes a load of debug message boxes, and from that I think I've gathered a few (possibly) interesting/relevant things:

• $Open and $Conn are 8 byte values, which increments (not by 1) when the FTP connection is not closed, but if the connection is closed, they stick at the value (presumably windows can re-use that session id if it's been closed

e.g:

1st run (file not present) $Open -> 0x00CC0004 $Conn -> 0x00CC0008

2nd run (file not present) $Open -> 0x00CC0010 $Conn -> 0x00CC0014

3rd run (file now present) $Open -> 0x00CC001C $Conn -> 0x00CC0020

4th run (file still present) $Open -> 0x00CC001C $Conn -> 0x00CC0020

• $Ftp = _FTP_FileGet.... returns a 1 when file not present (in a run after it was present) and "test_transfer.txt" does get created and does contain the correct string

This is the key bit I dont understand, I dont know how/where it is getting the data to write this file when it literally no longer exists on the target FTP server...

• resetting every variable used in the function each time it's run does work (in that they become 0), but it doesn't affect the putcome

I had thought perhaps some key values were being stored in the variables, but this doesn't seem to be the case

 

 

Is there any concept of clearing a cache when closing an ftp session? Or deleting any unknown temporary files windows might make?

 

Thanks all

 

expandcollapse popup

Func Transfer()
    Local $connected = 0
    $Ftpp = 0           ;Trying to reset these every time function is called
    $file = 0
    $Open = 0
    $Conn = 0
    $Ftpc = 0

    ;Make a new "connecting..." window so that the user has feedback that a transfer is attempting to take place
    ;Otherwise it just runs in the background and there's no indication its doing anything
    $connection_window = GUICreate ("Ethernet Switch Test" , 300 , 160 , -1 , -1 , -1 , -1 , 0)
    GUISetBkColor(0xFFFFFF)
    GUISetFont(10 * _GDIPlus_GraphicsGetDPIRatio()[0], 400, Default, "Sans Serif")
    $connecting_label = GUICtrlCreateLabel("Connecting to board...", 0, 25, 300, -1, $SS_Center, "")
    GUISetState(@SW_SHOW, $connection_window)
    Sleep(100)

    ;Connect
    ;MsgBox(0, "DEBUG", "1" & $Conn)
    While $connected = 0
        $Open = _FTP_Open($count)
        ;MsgBox(0, "DEBUG", "open " & $Open)
        $Conn = _FTP_Connect($Open, $server, $username, $password)
        ;MsgBox(0, "DEBUG", "2" & $Conn)
        If $Conn = 0 then
            Local $retry = Msgbox(65, 'FTP Transfer', 'Connection failed' & @CRLF & "Retry?")
            If $retry = 2 Then
                MsgBox(0, "FTP Transfer", "Operation aborted")
                GUISetState(@SW_HIDE, $connection_window)
                Return
            EndIf
        Else
            $connected_label = GUICtrlCreateLabel("Connected!", 0, 45, 300, -1, $SS_Center, "")
            $connected = 1
            MsgBox(0, "DEBUG", "3" & $connected)
            Sleep(100)
        endIf
    WEnd

    $transfering_label = GUICtrlCreateLabel("Reading file....", 0, 45, 300, -1, $SS_Center, "")

    ;Read file from server
    ;MsgBox(0, "DEBUG", "5" & $Ftpp)
    ;MsgBox(0, "DEBUG", "flie " & $file)
    $Ftpp = _FTP_FileGet($Conn, 'test/test.txt', 'test_transfer.txt')
    ;MsgBox(0, "DEBUG", "6" & $Ftpp)
    If ($Ftpp) then
        $transfered_label = GUICtrlCreateLabel("Transfered, checking...", 0, 65, 300, -1, $SS_Center, "")
        ;MsgBox(0, "DEBUG", "flie " & $file)
        $file = FileRead("test_transfer.txt")
        ;MsgBox(0, "DEBUG", "flie " & $file)
        If Not StringInStr($file, 'this is a test string 12345') Then
            MsgBox(0, "File check", "Received file incorrect, test failed!")
            GUISetState(@SW_HIDE, $connection_window)
            Return
        Else
            $tested_label = GUICtrlCreateLabel("Tested and Passed!", 0, 85, 300, -1, $SS_Center, "")
            $Ftpc = _FTP_Close($Open)
            ;MsgBox(0, "DEBUG", "close" & $Ftpc)
            ;$count = $count+1
            $ok_button = GUICtrlCreateButton("OK", 125, 105, 50, -1)
            While 1
                Local $pressed = GUIGetMsg()
                If ($pressed = $ok_button) Then
                    FileDelete("test_transfer.txt")
                    GUISetState(@SW_HIDE, $connection_window)
                    ;$connection_window = 0
                    Return
                EndIf
            WEnd
        EndIf
    Else
        MsgBox(0, "Transfer", "Could not read file " & @error)
        GUISetState(@SW_HIDE, $connection_window)
        Return
    EndIf

EndFunc

 

[Andreik]

You can use  $INTERNET_FLAG_RELOAD in _FTP_Open() to force the download from the origin server instead from cache.

Edited March 7, 2018 by Andreik

[CharlieH]

45 minutes ago, Andreik said:

You can use  $INTERNET_FLAG_RELOAD in _FTP_Open() to force the download from the origin server instead from cache.

Many thanks for the suggestion, I've now edited the _FTP_Open call:

$Open = _FTP_Open($count, $INTERNET_OPEN_TYPE_DIRECT, '', '', $INTERNET_FLAG_RELOAD)

However, this hasn't solved the issue I was having... :/

Is the above syntax correct? Can I avoid the extra overflow parameters or do I need all to send the iFlags?

[Andreik]

Sorry, my mistake, I wanted to say to use this flag in _FTP_FileGet().

[CharlieH]

Ah, amazing thanks! All sorted now.