[DNSOP] SVCB ALPN value presentation format

Larry Campbell <lcampbel@akamai.com> Sat, 13 June 2020 14:53 UTC

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From: Larry Campbell <lcampbel@akamai.com>
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Subject: [DNSOP] SVCB ALPN value presentation format
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Seciont 6.1 says:

> The presentation value of "alpn" is a comma-separated list of one or more "alpn-id"s. Any commas present in the protocol-id are escaped by a backslash:
> 
>     escaped-octet = %x00-2b / "\," / %x2d-5b / "\\" / %x5D-FF
>     escaped-id = 1*(escaped-octet)
>     alpn-value = escaped-id *("," escaped-id)

If I read this correctly, the presentation value is allowed to contain nulls and control characters. This seems likely to make such records very difficult to edit. Wouldn't it be better to require these to be encoded as \nnn?

- lc