File Download Problem

[lintz]

I use the below code to check and download updates for my app. The problem i've run into is if a user has a Download Manager enabled (eg. DAP), the Downlad Manager downloads the file and overwrites my code as to where the file should be downloaded to.

Is there a way I can disable the Download Manager or another way to over come my problem?

Option Explicit
Private Declare Function URLDownloadToFile Lib "urlmon" Alias _
    "URLDownloadToFileA" (ByVal pCaller As Long, ByVal szURL As String, _
    ByVal szFileName As String, ByVal dwReserved As Long, _
    ByVal lpfnCB As Long) As Long
 
Private Sub Form_Load()
Dim url As String
Dim localFileName As String
Dim errcode As Long
 
 
url = "http://www.mysite.com/myfile.txt"
localFileName = App.Path & "\myfile.dat"
errcode = URLDownloadToFile(0, url, localFileName, 0, 0)
 
End Sub

[Disiance]

Don't use the URLDownloadToFile API *gasp!*

Plugin a winsock control instead, connect on port 80, send the nessicary headers and download.

Disiance

[vbNeo]

Would you mind telling him what the headers are instead of being a b*tch about it? I'm interested in this information as well.

[Disiance]

Originally posted by vbNeo
Would you mind telling him what the headers are instead of being a b*tch about it? I'm interested in this information as well.

I thought maybe you could take an initiative and look it up yourself, guess not. Anywho, connect to the server and send the following:

GET /filename.extension HTTP/1.1

This tells the server what file you're after, starting after the domain name. e.g., if the file is http://www.domain.com/folder/file.zip then this line would read
GET /folder/file.zip HTTP/1.1

Host: www.google.com

This would be "www.domain.com" going from the above example. This is needed because some servers run multiple domains, it needs to know which it's looking for.

You may want to add

Connection: Keep-Alive

but that's your choice.

When sending this through Winsock, MAKE SURE to add vbCrLf to the end of the line, I kept leaving this off and it drove me nuts as the server wouldn't respond.

After sending the above headers send a blank line, e.g., Winsock1.Senddata vbCrLf

The server will respond with some information about itself and the filesize, then will start sending the file. The server will trigger a disconnect when the file has been sent.

Disiance

[Disiance]

Ok, I have made a sample program to help clear things up:

Private DLFile As String
 
Private Sub Command1_Click()
    Winsock1.RemoteHost = txtServer
    Winsock1.RemotePort = 80
    Winsock1.Connect
    Do Until Winsock1.State = 7
        DoEvents
    Loop
    Winsock1.SendData "GET " & txtFile & " HTTP/1.1" & vbCrLf
    DoEvents
    Winsock1.SendData "Host: " & txtServer & vbCrLf
    DoEvents
    Winsock1.SendData vbCrLf
End Sub
 
Private Sub Winsock1_DataArrival(ByVal bytesTotal As Long)
    Dim NewData As String
    Winsock1.GetData NewData
    DLFile = DLFile & NewData
End Sub

It has a winsock named Winsock1
Two textboxes, txtServer and txtFile
The txtServer is the server name e.g. "www.domain.com"
The txtFile is the file string, e.g. "/folder/file.zip"

The code will fill variable DLFile with the file (plus headers). I do not recommend downloading into a textbox because textboxes will leave some non-displayable characters out, so I'd download directly into a file, or a variable like shown above. Note the variable can only store about 2 billion characters, so I wouldn't use it for extremely large file downloads, but program updates it should be fine.

I was wrong in the above post, the server will not close the connection for you, so you'll have to parse the "Content-Length" header it sends and see when it has been reached.

Disiance