W3C home > Mailing lists > Public > ietf-http-wg@w3.org > July to September 2009

Re: NULL paths in requests

From: Adrien de Croy <adrien@qbik.com>
Date: Sun, 05 Jul 2009 12:07:40 +1200
Message-ID: <4A4FEECC.5050709@qbik.com>
To: "Roy T. Fielding" <fielding@gbiv.com>
CC: HTTP Working Group <ietf-http-wg@w3.org>


Roy T. Fielding wrote:
> On Jul 3, 2009, at 8:23 PM, Adrien de Croy wrote:
>
>> I've found a client that sends requests (when configured to use a 
>> proxy) like:
>>
>> GET  HTTP/1.1
>> Host: some host
>>
>> e.g. 2 spaces between GET and HTTP/1.1
>>
>> Is this deemed a "NULL" path?
>
> No, it is just a broken request.  Respond with 400 or 404, depending on
> whether you want to interpret it as a 1.1 request or 0.9 request.
turns out this was coming out the other side of a proxy, and what was 
going in was a absolute-URI missing a final '/'

In which case I think a proxy is allowed to add it back in.

>
>> In httpbis-p1-messaging-06.txt it talks about
>>
>>  A transparent proxy MUST NOT rewrite the "path-absolute" part of the
>>   received request-target when forwarding it to the next inbound
>>   server, except as noted above to replace a null path-absolute with
>>   "/".
>>
>>
>> However this doesn't make much sense, since what is a transparent proxy?
>
> It is defined in the spec.
>
>> Is this one that intercepted the TCP connection?
>
> No. It is a proxy that is not designed to transform requests or responses
> to something other than was requested/responded.
>
>> Otherwise it should have received a request in the form absolute-URI, 
>> which isn't allowed to be rewritten as above.  Or is it?
>
> It must be rewritten when a request is forwarded to an origin server.
> The above is specifically talking about the path part.
>
>> In fact path-absolute isn't necessarily a part of the request-URI, it 
>> could be the whole request-URI.
>
> Not on a request to a proxy.
>
>> Actually absolute-URI as per RFC 3986 seems to allow a lot more forms 
>> than it did in RFC2616.  Is this desired?  I'd presume not.
>>
>> from RFC 3986
>>
>>   absolute-URI  = scheme ":" hier-part [ "?" query ]
>>
>>   hier-part     = "//" authority path-abempty
>>                 / path-absolute
>>                 / path-rootless
>>                 / path-empty
>>
>>
>> e.g. in the old form, the path-absolute, path-rootless, and 
>> path-empty forms were not allowed as part of absolute-URI.
>
> Please read the ABNF from left to right.
you mean I should read it as

hier-part = "//" authority (path-abempty / path-absolute / path-rootless 
/ path-empty)

rather than

hier-part = ( "//" authority path-abempty) / (path-absolute) / 
(path-rootless) / (path-empty)

?

Thanks

Adrien

>
> ....Roy
>

-- 
Adrien de Croy - WinGate Proxy Server - http://www.wingate.com
Received on Sunday, 5 July 2009 00:04:58 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Friday, 27 April 2012 06:51:07 GMT