Ticket History #1383: SRV record "." target, trailing dots

# Fri Mar 14 19:07:14 2003 raeburn (Ken Raeburn) - Ticket created

To:	krb5-bugs@MIT.EDU
Subject:	SRV record support
From:	Ken Raeburn <raeburn@MIT.EDU>
Date:	Fri, 14 Mar 2003 19:07:10 -0500

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The RFC says a SRV record can have a target name of ".", meaning
"service not available". We don't handle that case.

I think (but can't quite confirm, yet) that the target name is
supposed to be a complete name. So if a hostname is returned without
a trailing ".", we might want to add one before looking it up.

Ken

# Fri Mar 14 19:45:44 2003 tlyu (Taylor Yu) - Correspondence added

To:	rt@krbdev.mit.edu
Subject:	Re: [krbdev.mit.edu #1383] SRV record support
From:	Tom Yu <tlyu@mit.edu>
Date:	Fri, 14 Mar 2003 19:45:43 -0500
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>>>>> "Ken" == Ken Raeburn via RT <rt-comment@krbdev.mit.edu> writes:

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Ken> I think (but can't quite confirm, yet) that the target name is
Ken> supposed to be a complete name. So if a hostname is returned without
Ken> a trailing ".", we might want to add one before looking it up.

RFC 1035 says that a <domain-name> is terminated with a zero-length
label, which seems to indicate that the target name is absolute.

RFC 1034 also indicates that relative names are mostly a user
interface thing.

---Tom

# Thu Oct 07 18:48:28 2004 tlyu (Taylor Yu) - Correspondence added

To:	rt@krbdev.mit.edu
Subject:	Re: [krbdev.mit.edu #1383] SRV record support
From:	Tom Yu <tlyu@mit.edu>
Date:	Thu, 07 Oct 2004 18:48:26 -0400
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>>>>> "Ken" == Ken Raeburn via RT <rt-comment@krbdev.mit.edu> writes:

Show quoted text

Ken> I think (but can't quite confirm, yet) that the target name is
Ken> supposed to be a complete name. So if a hostname is returned without
Ken> a trailing ".", we might want to add one before looking it up.

I checked a little bit of the source code of dn_expand() and
ns_name_uncompress(), and neither returns a trailing dot unless the
root domain is what's being expanded. Even though a SRV record is
supposed to have a complete domain name as the target, and would
logically be represented with a trailing dot, the resolver API doesn't
show us the trailing dot. This means that we'll have to explicitly
append a trailing dot so that further lookups will bypass the local
domain search.

---Tom

# Thu Oct 07 18:51:03 2004 tlyu (Taylor Yu) - Subject changed from 'SRV record support' to 'SRV record "." target, trailing dots'

# Thu Oct 07 18:51:04 2004 tlyu (Taylor Yu) - Status changed from 'new' to 'open'

# Thu Oct 07 18:51:05 2004 tlyu (Taylor Yu) - Component krb5-libs added

# Thu Dec 09 20:45:13 2004 tlyu (Taylor Yu) - Status changed from 'open' to 'resolved'

# Thu Dec 09 20:45:13 2004 tlyu (Taylor Yu) - Version_Fixed 1.4 added

# Thu Dec 09 20:45:14 2004 tlyu (Taylor Yu) - Comments added

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Trailing "." appended already in lib/krb5/os/dnssrv.c:5.7. Closing.