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Re: Feature request about curlinfo option returning resolver status/error code

From: Timothe Litt <litt_at_acm.org>
Date: Wed, 20 Apr 2022 16:34:27 -0400


On 19-Apr-22 18:26, Dan Fandrich via curl-library wrote:
> On Tue, Apr 19, 2022 at 04:14:23PM -0400, Timothe Litt via curl-library wrote:
>> No.  No need to invent abstract codes.  Use the DNS RCODE + (if available) the
>> ENS EDNS0 EDE (RFC8914).
> But do those codes include errors that only a local resolver might face? Things
> like access or syntax errors on /etc/resolv.conf, inability to connect to the
> local resolver daemon, or out of memory? In just looking at the set of c-ares
> error codes, they're defined in sections with 6 in the "server error codes"
> section and 11 in the "locally-generated error codes" section.

No, but that's why I suggested optionally including resolver-specific
codes at the end of the structure.

The point is to allow an application to be independent of the resolver
without learning a new, curl-specific vocabulary.  And, when new codes
are introduced in DNS, not to have to update curl with new abstract
codes - at least when the resolver supports getting the actual DNS error
code.

You would map any resolver codes that don't come from DNS to a code in
the "Reserved for Private Use" space.

You can also provide the text for humans.

See the RFCs and the code registries at:

https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-6

https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#extended-dns-error-codes


Timothe Litt
ACM Distinguished Engineer
--------------------------
This communication may not represent the ACM or my employer's views,
if any, on the matters discussed.


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Received on 2022-04-20