On 6/23/05, jean-frederic clere <[EMAIL PROTECTED]> wrote:
> Jeff Trawick wrote:
> > On 6/23/05, jean-frederic clere <[EMAIL PROTECTED]> wrote:
> >
> >>William A. Rowe, Jr. wrote:
> >>
> >>>++1 To Joe's comments.
> >>>
> >>>Jeff's fix is technically right, but scares the nibbles out
> >>>of me. If, for example, an exploit is able to inject the
> >>>T-E on top of the legit C-L, I really suspect we should not
> >>>trust the origin server at all.
> >
> >
> > One important situation to fear is a buggy server or proxy+server that
> > we may not be able to talk to at all if we are extremely strict.
> >
> > [As you implied w.r.t. Apache 1.3] The smuggling fear is really if we
> > allow keepalive on this connection to the origin server again. We
> > could be confused by making the wrong choice from {CL, TE} and
> > misunderstand the next response. We can set backend->close and
> > origin->keepalive to prevent that.
> >
> > If we don't allow keepalive, then it is down to whether or not this
> > single request can be parsed correctly if our choice of {CL, TE} makes
> > sense.
> >
> >
> >>>For origin servers (as opposed to clients) make this choice
> >>>between ignore C-L, or fail, configurable?
> >
> >
> > try very hard to make a reasonable choice with no configuration :)
> > (speaking to the choir, of course)
> >
> >
> >>>My observation is that there are far more varied clients in
> >>>the world than servers, each with unique faults. But the
> >>>RFC 2616 is clear...
> >>>
> >>> Messages MUST NOT include both a Content-Length header field and a
> >>> non-identity transfer-coding. If the message does include a non-
> >>> identity transfer-coding, the Content-Length MUST be ignored.
> >>>
> >>> When a Content-Length is given in a message where a message-body is
> >>> allowed, its field value MUST exactly match the number of OCTETs in
> >>> the message-body. HTTP/1.1 user agents MUST notify the user when an
> >>> invalid length is received and detected.
> >>>
> >>>...and server authors can be expected to be less buggy than clients.
> >>>"Permissive in what we accept, strict in what we send" implies some
> >>>strictness in what we trust to pass on to the client.
> >
> >
> > We're removing the protocol breakage in what we pass on to the client.
> > At this point, we either send a valid response or it is if the server
> > dropped the connection before sending the full response.
> >
> > (I hear what you're screaming. I think the minimal-intervention path
> > should be preferred if we can justify it.)
> >
> >
> >>>So +.5 to Jeff's patch, and let's discuss if the proxy response should
> >>>then be trusted at all with T-E and C-L, in httpd-2.x where we support
> >>>keepalives.
> >>
> >>Once the patch applied we lose the information that the request was
> >>"incorrect".
> >>That means we won't be able to choose in proxy between sending C-L (and
> >>dechunk)
> >>and T-E.
> >
> >
> > I don't follow here. How does the backend choice of {TE, CL} affect
> > what we send the client?
> >
> >
>
> If we are acting as a proxy, what we send to the next proxy is changed by the
> patch, isn't it?
This second patch is a bit confusing out of context because of the use
by that function of r->headers_OUT for information we have READ from
the origin server. It doesn't affect what we send to the next proxy
as far as I can tell.
The original patch could affect what we send to the next proxy.
