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From "Ed Korthof" ...@organic.com>
Subject AOL's Proxy Is Broken
Date Thu, 19 Dec 1996 23:13:35 GMT
The answer we have recieved (indirectly) from AOL regarding AOL's policy of
rejecting messages begining with "HTTP/1.1" is below.  This answer is
incorrect.  After recieving numerous reports of this, rather than fixing the
problems of their proxy server, the AOL proxy team things made it worse.
 Originally, only AOL 3.0 for Windows had the problem; now all versions we've
been able to test have it (so far as we can tell, it is a problem with the
proxy).  Please forward this message to your proxy team and tell them to fix
their broken software.

For the relevant portions of the HTTP specification, please see
<http://www.graphcomp.com/info/specs/http10.html#HTTP-Version> for HTTP/1.0 and
 <http://www.graphcomp.com/info/specs/http11.html#HTTP-Version> for the
HTTP/1.1 statement.

In brief, an HTTP/1.0 server must accept requests and responses from any
HTTP/1.x client or server, as well as those from HTTP/0.9.  Responses from an
HTTP/1.1 server are guaranteed to be comprehensible by an HTTP/1.0 server or
client (so long as the request was HTTP/1.0).  Since Apache recieves an
HTTP/1.0 request from AOL's proxies, it responses with a valid HTTP/1.0
response; it indicates it's version is HTTP/1.1 *so that your server/client
will know it can send HTTP/1.1 requests if it wants to*.  This is a method of
communicating HTTP version and capabilities.

Your proxy is well within its rights to translate an HTTP/1.1 request to
HTTP/1.0; it is not correct to drop HTTP/1.1 responses.  To quote from the
HTTP/1.0 specification (note the second sentence):

"HTTP uses a "<major>.<minor>" numbering scheme to indicate versions of the
protocol. The protocol versioning policy is intended to allow the sender to
indicate the format of a message and its capacity for understanding further
HTTP communication, rather than the features obtained via that communication.
No change is made to the version number for the addition of message components
which do not affect communication behavior or which only add to extensible
field values. The <minor> number is incremented when the changes made to the
protocol add features which do not change the general message parsing
algorithm, but which may add to the message semantics and imply additional
capabilities of the sender. The <major> number is incremented when the format
of a message within the protocol is changed."

Further, as soon as we changed the first line from "HTTP/1.1 ..." to "HTTP/1.0
..." (*nothing* changed other than the version number), things magically
worked.

Please fix your bloody proxy so that HTTP/1.1 can be implemented without ugly
hacks to send an old version number to AOL clients and servers.

I have included the Apache development team in this e-mail; I should add that
the two people addressed at AOL are not themselves part of the proxy team and
are not the people deserving flames.  They've sent prompt and resonable
responses.

On Dec 19,  1:07pm, uppity woman wrote:
> Subject: info from aol
>
> this came out of some correspondance at aol about the problem ...
>
> ---------------- Begin Forwarded Message ----------------
> This message comes from sites that do not issue explicit HTTP/1.0
> responses to HTTP/1.0 requests.  In the past we've had problems with
> sites returning HTTP/0.9 responses and only the "compressed" side was
> able to filter them out (issuing "cannot retreive..." messages.  Now
> those sites can be caught on both compressed and uncompressed sides of
> the house.
>
> However, a new problem was emerging on the horizon.  New HTTP/1.1 web
> servers are starting to generate HTTP/1.1 responses to HTTP/1.0 requests
> when they should be generating only HTTP/1.0 responses.  We wanted to
> stem the tide of those faults proliferating and becoming a de facto
> standard by blocking them now.  Hopefully the authors of those web
> servers will change their software to only generate HTTP/1.1 responses
> when an HTTP/1.1 request is submitted.
> ----------------- End Forwarded Message -----------------



-- 
     -- Ed Korthof        |  Web Server Engineer --
     -- ed@organic.com    |  Organic Online, Inc --
     -- (415) 278-5676    |  Fax: (415) 284-6891 --

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