httpd and form-based upload

[Alexander Kriegisch]

I wrote earlier:
>> I would like to know if httpd supports form-based uploads and how
>> they can be handled in plain shell scripts (/bin/sh). I would be glad
>> to see one or more sample script(s).

Some more background info: An HTML page for form-based upload could look like this:

<html>
<body>
  <form action="/cgi-bin/do_upload.cgi" method=post enctype="multipart/form-data">
    <input type=file size=50 maxlength=100000 name="File"><br>
    <input type=submit value="Submit">
  </form>
</body>
</html>

A server-side script receiving the upload could look like this:

#!/bin/sh
echo -n -e 'HTTP/1.0 200 OK\r\n'
echo -n -e 'Content-type: text/html\r\n\r\n'

cat > /var/tmp/upload.bin
cat << EOF
<html>
<body>
  <h2>Upload finished</h2>
</body>
</html>
EOF

And this would be the content of upload.bin:

-----------------------------7d72033ac0372
Content-Disposition: form-data; name="File"; filename="I:\install\sample_upload.tar.gz"
Content-Type: application/x-gzip

(...) unencoded binary stuff (...)
-----------------------------7d72033ac0372--

So, basically, I would need a shell script which could
cut away the MIME header and footer, so as to only save 
the "unencoded binary stuff" section to disk. This may 
not be a very busybox-specific question, but anyway, 
probably I should use the limited means provided by 
busybox's shell (ash) and toolset (sed, awk, maybe others) 
to achieve. I was also hoping for an httpd  configuration
option to help me achieve my goal without having to code
a CGI upload handler in C. BTW: My busybox is running on
a DSL router.
--
Alexander Kriegisch