Winsock file transfer issue (through Internet only?)

Hi, I'm using the Winsock OCX in VB6 to create a personal file server application, and it transfer files perfectly within the LAN, but not the Internet. If I access it via localhost or the machine name over LAN, it works perfect. But when accessing via the Internet IP, only the first block of the file arrives to the user's browser. However it is entirely sent, no errors appear in the server application. :(

The main code to send the file is below, taken from DigiRev's Send File With Winsock code and modified to make it politely wait for the SendComplete event before sending the next chunk of data. Didn't fix the problem anyway.

Code:

---

Open FilePath For Binary Access Read As #lonFF
   
    ReDim bytData(1 To PacketSize) As Byte
   
    Do Until (lonSize - lonCurByte) < PacketSize
        Get #lonFF, lonCurByte + 1, bytData()
        lonCurByte = lonCurByte + PacketSize
       
        Do While sendComplete = False
            DoEvents '-- wait for the sendComplete event from winsock (using a flag)
        Loop
       
        Debug.Print SocketObject.State '-- show socket state (sckConnected)
        Debug.Print "Sending block " & lonCurByte
       
        sendComplete = False
        SocketObject.SendData bytData()
        DoEvents
    Loop
   
    lonPrevSize = lonSize - lonCurByte
   
    If lonPrevSize > 0 Then
        ReDim bytData(1 To lonPrevSize) As Byte
        Get #lonFF, lonCurByte + 1, bytData()
        lonCurByte = lonCurByte + lonPrevSize
       
        Do While sendComplete = False
            DoEvents '-- wait for the sendComplete event from winsock (using a flag)
        Loop
       
        Debug.Print SocketObject.State '-- show socket state (sckConnnected)
        Debug.Print "Sending final block..."
       
        sendComplete = False
        SocketObject.SendData bytData()
        DoEvents
    End If

Close #lonFF

---

Also tried with the UniSock API and the result is the same. And I used the Winsock repair utility just in case, of course it was useless. Also tried all possible block sizes: 1024, 2048, 4096, 8192... always the first block arrives to destination, and the browser keeps "Loading..." forever.

ANY help wil be greatly appreciated. I'm not sending any headers before sending the file, I've tried that but didn't fix anything. And if it works OK over LAN, why it fails when accessing the server using the Internet IP? :ehh:

I suspect the problem is not with the sending,more likely with the receiving. Can you post the receiving code (ie the winsock_dataarrival code)?

Not sure what example you went by, but there is no need for any DoEvents calls in proper Winsock code. You've written this is some sort of pseudo-blocking fashion. Your "triggering" event handler should just open the file and send the first block. Subsequent blocks (and file close after EOF) would be done within the SendComplete event handler.

I agree that your root problem is most likely in the receving code though.

Thanks, I've taken the code just as suggested here and it seems the code is correct and works.

I have no receiving code, that would be Firefox and Internet Explorer, because my program servers the pages with the content in an FTP-fashion (via HTTP of course) and sends the requested file to to browser.

Are you suggesting that I send the rest of the blocks of the file from the SendComplete event itself? I doubt that will make any difference... please try to explain because my english might not be good enough to understand, sorry!

Thanks