Re: partial URLs ? (was <p> ... </p>)

William C. Cheng (
Wed, 20 Dec 1995 23:02:58 -0500

John Franks <> wrote:
> As I recall the draft RFC for URL's specifies that certain characters
> (like space) are forbidden, certain (like '?') have special meaning
> and otherwise the "path" part of a URL is an opaque string (which, in
> particular, may have nothing to do with a path). Neither '/' nor '.'
> are forbidden or have special meaning. They do have special meaning
> *for some implementations* and no special meaning for others.
> Likewise the colon may have special meaning for some implementations
> and not for others.
> The fact that certain strings may represent securtity risks for
> some implementations does not automatically make them illegal.
> I don't believe that "/../" is forbidden in HTTP URL's. If
> I am wrong I would be interested in a reference.
> It would, of course, be quite reasonable for the HTTP spec to have
> a UNIX-centric warning to implementors that they should make this
> string illegal for their implementation (or risk the consequences).

It seems to be true that "/../" is not forbidden explicitely. Now,
can anyone give me an example where http://foo/b/../bar.html and
http://foo/bar.html should _not_ be interpreted the same way? Forget
about the UNIX-centric business (we all know where DOS gets its "\"
and Mac gets its ":") because all these systems basically have
hierarchical file systems. So the real question is whether a "/"
separator in an URL implies a level change in a hierarchy.

Bill Cheng // Guest at Columbia Unversity Computer Science Department
william@CS.COLUMBIA.EDU      ...!{uunet|ucbvax}!!william
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