Forum: Mongrel Transfer-Encoding: Chunked

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C17cd6b14963e9cdbe3ad320ea575e7e?d=identicon&s=25 Zachary Roetemeyer (Guest)
on 2008-02-15 21:37
(Received via mailing list)
I'm working with someone who is having issues with a Transfer-
Encoding: Chunked upload. With out a content-length set in the
request, everything is treating the content length as 0 and the file
is more or less getting sent to the bit bucket.  Does anyone have any
experience with this kind of issue?  We started proxying with
nginx(returned a HTTP Error 411), then we tried to directly expose a
mongrel and ended up getting strange results, and errors in the
mongrel logs.  The client is uploading with a mobile phone using J2ME.

  Zachary Roetemeyer
B984299ceb40752b58146714eb192554?d=identicon&s=25 ry dahl (Guest)
on 2008-02-16 00:54
(Received via mailing list)
> With out a content-length set in the
>  request, everything is treating the content length as 0 and the file
>  is more or less getting sent to the bit bucket.

Is the content length header really not getting set? Mongrel
automatically sets this. If you do something like while writing the
response code. You might have to overload mongrel's
HttpResponse#send_status method to explicitly not send this header.

I think http://merb.devjavu.com/ticket/121 might have some useful hints
too.

ry
0847706937d26cc1377a447240e71d84?d=identicon&s=25 Eden Li (Guest)
on 2008-02-16 05:40
(Received via mailing list)
Looks like mongrel can't handle chunked posts (see
http://mongrel.rubyforge.org/svn/trunk/lib/mongrel...
line 29).  You'll need to put another web server (other than nginx) in
front of it to handle this, or you could file a bug in the mongrel
tracker to get them to add this support (or you could code it up
yourself :).
E7cff3cfd41c495e1012227d7dc24202?d=identicon&s=25 Luis Lavena (luislavena)
on 2008-02-16 05:46
(Received via mailing list)
On Feb 15, 2008 9:53 PM, ry dahl <ry@tinyclouds.org> wrote:
> > With out a content-length set in the
> >  request, everything is treating the content length as 0 and the file
> >  is more or less getting sent to the bit bucket.
>
> I think http://merb.devjavu.com/ticket/121 might have some useful hints too.
>

Oh, got lost, there is merb.devjavu.com and also merb.lighthouseapp.com
?
:-P

--
Luis Lavena
Multimedia systems
-
A common mistake that people make when trying to design
something completely foolproof is to underestimate
the ingenuity of complete fools.
Douglas Adams
8c43ed7f065406bf171c0f3eb32cf615?d=identicon&s=25 Zed A. Shaw (Guest)
on 2008-02-17 03:23
(Received via mailing list)
On Fri, 15 Feb 2008 14:35:04 -0600
Zachary Roetemeyer <zprime@gmail.com> wrote:

> I'm working with someone who is having issues with a Transfer-
> Encoding: Chunked upload. With out a content-length set in the
> request, everything is treating the content length as 0 and the file
> is more or less getting sent to the bit bucket.  Does anyone have any
> experience with this kind of issue?  We started proxying with
> nginx(returned a HTTP Error 411), then we tried to directly expose a
> mongrel and ended up getting strange results, and errors in the
> mongrel logs.  The client is uploading with a mobile phone using J2ME.

Uh, you aren't allowed to set a Content-Length AND use CE in the same
request.  That would let the two contradict so it's an RFC violation.
Actually, WebLogic makes this mistake and we had to school them about
it until they told us to turn it off.  (WebLogic is such a piece of
shit).

My RFC knowledge on CE is rusty since I banished that shitty part of
HTTP from my mind when I implemented it in RFuzz, but my thoughts are:

1) CE wasn't designed for clients to upload, since no browser does it.
2) It's originally for a server to send periodic parts of a request
without having to know it's total final size.
3) Anyone doing a CE as a client is seriously screwing with the RFC and
really exercising the corners of it for no apparent reason since CE
isn't needed by a client (the client knows the size, or better).
4) This puts a burden on the server to process the CE as it comes
over, which has the same problems as mime boundaries but with a more
horribly designed part of the RFC.
5) My recommendation is that you just don't do this.  The value add for
a client (or even modern servers really) is quite minimal.

Now, how you go about implementing it:

A) Read up on how to write a Mongrel handler.
B) Register it at the front of your web app or create a separate server
that runs just mongrel (probably your best if you want any kind of
performance).
C) Your handler would detect the CE via the normal headers and such,
and then process the final request body as it comes in for each chunk.
D) This might involve subclassing the Http processing parts that handle
the body and doing a bit of other hacking, and it's seriously fucking
dumb because after that you've gotta process mime boundaries and other
stuff, which will punish your server heavily.

Enjoy!

--
Zed A. Shaw
- Hate: http://savingtheinternetwithhate.com/
- Good: http://www.zedshaw.com/
- Evil: http://yearofevil.com/
C17cd6b14963e9cdbe3ad320ea575e7e?d=identicon&s=25 Zachary Roetemeyer (Guest)
on 2008-02-18 13:40
(Received via mailing list)
The upload is coming from a mobile device with J2ME, and it does this
by default with anything over 2K, and apparently there's no way to
turn it off.

On Feb 17, 2008, at 8:18 PM, Zed A. Shaw wrote:

>> mongrel logs.  The client is uploading with a mobile phone using
>
> 5) My recommendation is that you just don't do this.  The value add
> C) Your handler would detect the CE via the normal headers and such,
> Zed A. Shaw
> - Hate: http://savingtheinternetwithhate.com/
> - Good: http://www.zedshaw.com/
> - Evil: http://yearofevil.com/
> _______________________________________________
> Mongrel-users mailing list
> Mongrel-users@rubyforge.org
> http://rubyforge.org/mailman/listinfo/mongrel-users

Zachary Roetemeyer
zprime@gmail.com
714df4094c6cc4a71b835b5ed3668f6b?d=identicon&s=25 Todd Fisher (Guest)
on 2008-02-18 21:45
(Received via mailing list)
I implemented a chunked transfer encoding to handle ESI in pages... Each
fragment is sent as a chunk... Since, I can't determine ahead of time
what
the content-length would be as the individual ESI fragments are of
unknown
length until the page is assembled...
 I can see where a mobile device might want to do this because of memory
constraints, however.... if the device has what's it's sending stored
somewhere one would hope it can measure that something's length, ahead
of
time - writing the Content-length first... Then connect the write end of
the
socket to the read end of the file...   and away it goes never storing
more
then the OS decides to keep in memory...

This page might be helpful...
http://www.jmarshall.com/easy/http/#http1.1c2
0847706937d26cc1377a447240e71d84?d=identicon&s=25 Eden Li (Guest)
on 2008-02-19 01:37
(Received via mailing list)
Mind posting a patch?

As an aside, the j2me people seem to think CE requests are part the
http 1.1 spec (rfc2616):

   http://developers.sun.com/mobility/midp/questions/chunking/

and the minimal justification they give is that "interactive
applications may not know ahead of time how much data they're going to
send" (paraphrase).
8c43ed7f065406bf171c0f3eb32cf615?d=identicon&s=25 Zed A. Shaw (Guest)
on 2008-02-19 06:09
(Received via mailing list)
On Tue, 19 Feb 2008 08:36:43 +0800
Eden Li <eden@mojiti.com> wrote:

> Mind posting a patch?
>
> As an aside, the j2me people seem to think CE requests are part the
> http 1.1 spec (rfc2616):
>
>    http://developers.sun.com/mobility/midp/questions/chunking/
>
> and the minimal justification they give is that "interactive
> applications may not know ahead of time how much data they're going to
> send" (paraphrase).

Alright, let's see the code being used.  If this is truly the only way
to submit a request from a memory constrained device, and I can't find
an alternative that's simpler then I'll add CE to the Mongrel handler.
CE is already in the RFuzz handler so it'd be nothing more than putting
the same code in the Mongrel parser.  Of course this will just be an
exercise and I'll let the mongrel crew decide if they want it in or not.

And when I say "see the code" I don't mean a toy version, I mean the
actual code being used to do the upload that I can work with and test.
Doesn't have to be the full app, but enough for me to run in a MIDP
emulator and try out.

--
Zed A. Shaw
- Hate: http://savingtheinternetwithhate.com/
- Good: http://www.zedshaw.com/
- Evil: http://yearofevil.com/
0847706937d26cc1377a447240e71d84?d=identicon&s=25 Eden Li (Guest)
on 2008-02-20 04:04
(Received via mailing list)
Zachary, mind posting some of the code you're using in J2ME?  I've got
no dog in this fight.
C17cd6b14963e9cdbe3ad320ea575e7e?d=identicon&s=25 Zachary Roetemeyer (Guest)
on 2008-02-20 13:53
(Received via mailing list)
I'll have to see what I can do since the code isn't mine.

On Feb 19, 2008, at 9:03 PM, Eden Li wrote:

>>> As an aside, the j2me people seem to think CE requests are part the
>> way
>> And when I say "see the code" I don't mean a toy version, I mean the
>> _______________________________________________
>> Mongrel-users mailing list
>> Mongrel-users@rubyforge.org
>> http://rubyforge.org/mailman/listinfo/mongrel-users
>

Zachary Roetemeyer
zprime@gmail.com
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