Re: [dnsext] New RRtype "KREALM" in draft-vanrein-dnstxt-krb1-02.txt

Rick van Rein <rick@openfortress.nl> Fri, 11 September 2015 11:05 UTC

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Date: Fri, 11 Sep 2015 13:04:53 +0200
From: Rick van Rein <rick@openfortress.nl>
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To: Tony Finch <dot@dotat.at>
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Subject: Re: [dnsext] New RRtype "KREALM" in draft-vanrein-dnstxt-krb1-02.txt
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Hi Tony,

> Yes, I think the wire format and presentation format should be native DNS
> not ASN.1.

Ah.  That would call for more complex parsing.  I hadn't expected that to be preferred by the DNS community, over simplicity.  Is the reason readability of zone files?

HINFO uses precisely 2 strings, with KREALM it'd be variable, but could be done with something like

@ IN KREALM ( "realm=EXAMPLE.COM" "realm=EXAMPLE.ORG"
      admin=carl "admin=mary"
      service=HTTP "service=imap" )

The parser then MAY check the presence of an = sign in the string but otherwise keep tag and value together.

Each of these strings would then independently translate to a separate <character-string>, namely

12 72 65 61 6c 6d 3d 45 58 41 4d 50 4c 45 2e 43 4f 4d
12 72 65 61 6c 6d 3d 45 58 41 4d 50 4c 45 2e 4f 52 47
0b 61 64 6d 69 6e 3d 63 61 72 6c
0b 61 64 6d 69 6e 3d 6d 61 72 79
0d 73 65 72 76 69 63 65 3d 48 54 54 50
0d 73 65 72 76 69 63 65 3d 69 6d 61 70

But that's a variable number of strings in the textual format *and* in the RDATA format.  The RDATA is preceded by RDLENGTH, so it would be possible, but I am hesitant about such new approaches to DNS.

Alternatively, we could incorporate separator characters such as comma's but that would constrain the possible string values (and call for even more escaping and another level, which isn't my favourite place to go).

I expect an uproar from both alternatives to be honest.  Or not?

-Rick