[Dnsmasq-discuss] [RFC PATCH] Add a no-auto-edns compatibility option

[Dmitry Kuleshov]

Hi Simon,
I would like to propose an optional --no-auto-edns setting for compatibility with upstream DNS servers or intervening network devices which fail to handle queries carrying EDNS0.
Since dnsmasq 2.91, a plain upstream UDP query is automatically given an OPT record. Reducing --edns-packet-max still leaves that record present; this proposal allows administrators to suppress its automatic creation.
The attached patch changes only that default insertion step when the option is enabled. Existing OPT records are retained, including those supplied by clients or created by configured EDNS features or DNSSEC. The usual UDP-size adjustment still applies to an existing record. Default behaviour and TCP forwarding are unchanged. The patch includes help text and a manual entry.
Base: upstream master a9880c595f052d63859d6ed8aa86a3a6b007bf20.
The patch applies independently, without OpenWrt patches.
After rebasing, the default build, option/configuration checks and manual formatting were checked. Live upstream-query and DNSSEC protocol testing were not performed in this environment, so I am submitting this as an RFC.
I used AI assistance in preparing the change and its review. Would an opt-in compatibility setting with this scope be acceptable?
Best regards,
Dmitry
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