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From Dean Gaudet <dgau...@arctic.org>
Subject Re: Bug Report 5671 - CGI Deadlock
Date Sat, 05 Feb 2000 21:24:36 GMT
i'm pretty sure squid is full duplex... but i doubt mod_proxy is.  even
SSL doesn't require full-duplex, it just has a few back-and-forths which
fit inside most reasonably sized buffers.

to do this stuff properly really requires poll/select and careful state
machine programming.

it's ironic this topic is coming up right now... i just got my hands on
the early bind9 code and they've got a really nice async i/o abstraction
in it which could be used to build a really nice proxy.  the pieces are
coming together :)

Dean

On Sat, 5 Feb 2000, Mike Gray wrote:

> I am very curious what limitations a proxy server would have on this design.
> For example, if you have a proxy server sitting between the desktop browser
> software and the web server where your cgi is installed.  Will it let all of
> this traffic through?  Do most proxy servers allow full-duplex transmission?
> (obviously an SSL capable proxy would have to in order for the handshake to
> occur, right?)
> 
> mikeg
> 
> "William A. Rowe, Jr." wrote:
> 
> > Precisely, Dean.
> >
> >   I'm looking at hacking a full-duplex cgi (targeting 2.0, not 1.3.x!!!)
> >
> >   My metacode idea is;
> >
> >   while (get inbuf <- client) {
> >     write inbuf -> cgi stdinpipe
> >     while (!empty cgi stdoutpipe)
> >       read outbuf <- cgi stdoutpipe
> >       put outbuf -> client
> >   }
> >   while (!empty cgi stdoutpipe)
> >     read outbuf <- cgi stdoutpipe
> >     put outbuf -> client
> >   }
> >   close client connections
> >
> >   The problem I have is with the size of the pipes.  NT's are VERY small by
> > default.  I discovered this with a simple CGI writing the client stream back
> > at the client as a hexdump.
> >
> >   Limited application?  Perhaps... but it would appear to the browser as a
> > more async processes flow.  Thresholds would be required... delta time or
> > size, but I'll think that through if this proves worthwhile.
> >
> >   Additional thoughts anyone?
> >
> > Bill
> 
> 


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