openwrt / openwrt/packages

ddns-scripts: Setting a custom IPv6 `dns_server` is not possible

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Description

This check blocks IPv6 addresses in the configuration option dns_server '[2606:4700:4700::1111]':
https://github.com/openwrt/packages/blob/7e88aaacbd26f7a59eb4ffe58626ccb694e3c794/net/ddns-scripts/files/usr/lib/ddns/dynamic_dns_updater.sh#L259
Adapting that check will however still leave a the separate issue that GNU netcat does not accept IPv6 addresses:
https://github.com/openwrt/packages/blob/7e88aaacbd26f7a59eb4ffe58626ccb694e3c794/net/ddns-scripts/files/usr/lib/ddns/dynamic_dns_functions.sh#L591

root@FB3370:~# nc -v [2606:4700:4700::1111] 53
Error: Couldn't resolve host "[2606:4700:4700::1111]"

The workaround for that is to uninstall the netcat package and fall back to the busybox variant. Using something like socat might be the better option? If we don´t want to introduce that as a hard dependency then maybe using a check if that is installed?

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Research direction

Start in net/ddns-scripts/files/usr/lib/ddns/dynamic_dns_updater.sh around line 259 and inspect the IPv6 validation, then review dynamic_dns_functions.sh around line 591 for the netcat invocation. Confirm how the available netcat variants handle bracketed IPv6 addresses and define a working path for custom IPv6 DNS servers without requiring an unmentioned package change.

Written by the indexing model from the issue text.

Assessment

Tech stack
shell
Domain
networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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