Subject: Re: SRV records - when?

From: Alan Barrett <[email-masked]>
Date: Thu, 21 Mar 2002 15:57:17 +0200

On Sat, 09 Feb 2002, [email-masked] wrote:
> 	draft-andrews-http-srv-01.txt is available

"     If the URI does explicitly specify a port to connect to then there
"     is a potential conflict in the port specification between the URI
"     and the SRV records, and the SRV record is ignored.  In this case
"     the user agent MUST query for address records for the host name in
"     the URI (instead of SRV records).

It would be possible to prepend a port number to the left hand side of
the SRV record:

	8080._http._tcp.example.com. SRV   10 1 80 host2.example.com.

Also, the text and the examples disagree about what to do if there is an
explicit port number, but the explicit port number happens to be "80".

This replacement text fixes the problem with port 80, and suggests
a different way of handling non-defaulr ports:

   2. URIs with a explicit port specification

      If the URI explicitly specifies a port to connect to, and the
      explicit port is the same as the default port (that is, port 80),
      then the user agent MUST behave as if no explicit port had been
      specified.

      If the URI explicitly specifies a non-default port to connect
      to then there is a potential conflict in the port specification
      between the URI and the SRV records.  In this case, the user agent
      MUST NOT attempt to use SRV records for _http._tcp.<target>.
      Instead, the user agent MUST follow one of the following two
      strategies:

      A) Do not query for SRV records, and instead query for address
         records for the host name in the URI, and connect to the host
         address using the port number specified in the URI; or

      B) Do not query for SRV records for _http._tcp.<target>, but
         instead query for SRV records for <port>._http._tcp.<target>,
         where <port> is an ASCII decimal representation of the port
         number specified in the URI.  Apart from the insertion of the
         port number, follow the logic specified in [RFC2782], including
         the server selection mechanism provided by the priority and
         weight fields.  If these SRV records do not exist then the
         client MUST fall back to looking for IP address records.

--apb (Alan Barrett)