Re: Filter question

Eric Rosenquist (
Wed, 24 May 1995 16:42:40 -0400

> >From: Roland Hedberg <>
> > To:
> >
> > I issue a search for "Ake Sandgren"
> > (notice the special swedish character in the beginning, an A with an ring
> > above)
> > in a slightly modified version of web500gw, but that has little bearing
> > for this, since it uses standard ldap operations.
> >
> > The filter I see in the DSAs logfile is what I would expect
> >
> > | ((sn={T.61}\caAke Sandgren)(cn={T.61}\caAke Sandgren))
> >
> > but if this does not match then another filter is tried, an
> > approximate match, and I get the following strange filter
> >
> > | ((sn~={T.61}3AKE SANDGREN)(cn~={T.61}3AKE SANDGREN))
> >
> > Which, not surpricingly, doesn't match anything.
> I tried to duplicate this at our site and observed the following:
> 1. The problem doesn't seem to be in the LDAP client code -- it looks
> like the correct filters are being constructed there.
> 2. When our ldapd submits the search to a QUIPU DSA, the approximate
> search filter logged by QUIPU looks stange, as you observed. I
> tried this on an ICR1 DSA.
> 3. When our ldapd submits the search to the GDA DSA we run here for
> our primary service, the correct filters are logged in all cases.
> I didn't check to see if the searches work correctly or not, but it seems to
> me that QUIPU is doing something odd here, probably when it does some
> normalizing of the search filter to do the approximate searching. I didn't
> go as far as to look at the DSA code though.

I took a quick look at the DSA's soundex code (used for approximate string
matching) and it appears as though it knows nothing about T.61. I don't
know if Quipu is smart enough to strip T.61 accents etc before computing a
soundex value, but it didn't appear as though it handled it. I suspect
that the nonprinting T.61 characters would be interpreted as ASCII
characters and would probably throw off the soundex code computed for the

Why it doesn't handle exact matching properly is another question...

Eric Rosenquist, Senior Software Engineer, Enterprise Solutions Limited
Email: Fax: +1 (613) 591-3485 Opinions: are my own
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