Re: [Chicken-users] http egg can't parse valid HTTP headers

[Peter Bex]

On Wed, Feb 04, 2009 at 11:27:24PM -0800, Drew Hess wrote:
> Hi,
> 
> The regex used to parse HTTP headers in http:read-request-attributes in the
> http egg isn't quite right.
> 
>   (let ((rx (if (feature? 'pregexp) 
>               "([\\-A-Za-z0-9]+):[ ]*([^ ].*)"
>               "([-A-Za-z0-9]+):[ ]*([^ ].*)") ) )
> 
> RFC 2616 states in Section 4.2 that HTTP headers "follow the same generic
> format as that given in Section 3.1 of RFC 822." That means HTTP header
> field values may contain quoted strings with spaces, may be empty,
> or may even be multi-line (ugh).

You're right, this regex is wrong here.

> Unfortunately, properly parsing RFC 822 headers looks pretty hairy,
> mainly due to the multi-line case.

Yeah, you can say that again :). Because of the hairiness of the RFC and
the current brittleness of the HTTP egg (it has been hacked to pieces,
and accumulated quite a bit of cruft) I decided to start from scratch on
a new HTTP egg.  That new egg is called "intarweb", and it at least has
a testsuite (probably not big enough yet). Unfortunately, it's
Chicken 4 only, and not completely finished right now, so it won't help
you right this moment (unless you can switch), but I hope this gives you
some new hope :)

For the time being, I changed the HTTP egg's regex to remove the
"nonspace character" match at the start of the submatch group, so
"Foo: " and "Foo:" are allowed header values. Please give the new trunk
a shot, and let me know whether it works for you.

It hasn't been tagged yet, so it's not available through chicken-setup
yet, but you can fetch the trunk from
https://galinha.ucpel.tche.br/svn/chicken-eggs/release/3/http/trunk
(username: anonymous, no password)

Cheers,
Peter
-- 
http://sjamaan.ath.cx
--
"The process of preparing programs for a digital computer
 is especially attractive, not only because it can be economically
 and scientifically rewarding, but also because it can be an aesthetic
 experience much like composing poetry or music."
                                                        -- Donald Knuth

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