upload file using post to https server

[cerr]

hi,

I've been unsucessfully trying to upload a file using POST to an https
server.
I've succesfully logged in and gotten to read something from the
server..
I have come up with something like this:

        authinfo = urllib2.HTTPBasicAuthHandler()

        authinfo.add_password(realm='Configuration Software',
        uri=url,
        user='admin',
        passwd='******')

        opener = urllib2.build_opener(authinfo)
        pagePtr = opener.open(url)

        dataRead = str(pagePtr.read())

        #Look for 'Software Upload' in the page
        if( "Software Upload" in dataRead ):
          print "FOUND Software Upload in string...<BR>"
        else:
          print "Software Upload page not found.  Exiting..."
          sys.exit()

        values = { 'filename' : 'pAce34-7.1.2.3-5189k-efs.bin' }

        try:
                data = urllib.urlencode( values )
                req = urllib2.Request( url, data )
                #response = urllib2.urlopen( req )
                response = opener.open( req )

                the_page = response.read()
                #print the_page

        except Exception,detail:
                print "err ",detail

        #Look for 'file must be efs' in the page
        if( "file must be efs" in the_page ):
          print "file must be efs.  Exiting..."
          sys.exit()
        else:
          print "OK"

But the file doesn't seem to get there correctly. What I wanna do, is
mocking the upload from the html site with my python script.... the
html looks something like this:

<form method="post" action="/cgi-bin/config.pl" enctype="multipart/
form-data" onsubmit="return validateForm()" name="advance">
<input type="file" name="filename" tabindex="1"  size="57" /
>  <input type="submit" tabindex="2" name="submit"
value="Upload Image" /></form>

Thanks for your hints and suggestions on how I have to go about this!

Ron