luci-app-51ddns: add remote access agent interface

[21hkcloud]

Description

Add a LuCI interface for the open-source 51DDNS OpenWrt agent.

The page is available under Services > 51DDNS Remote Access and provides:

• account-token configuration with password masking;
• service status and installed agent version;
• current plan name, expiry and remaining time;
• a direct link to the 51DDNS console.

The application depends on 51ddns-agent, which is submitted separately in openwrt/packages#30158. The LuCI application is intentionally not bundled in the agent source archive.

Documentation and trust model

English installation, operation, privacy, troubleshooting and removal documentation:
https://www.51ddns.com/openwrt

Agent source and client privacy notice:
https://github.com/21hkcloud/51ddns-openwrt

The UI explicitly identifies 51DDNS as a vendor-hosted remote-access service. The agent uses the feed-provided frpc package and runs as a dedicated unprivileged user in a procd/ujail sandbox.

Testing

• The page and RPC helper use translatable English strings.
• ACL access is limited to the 51DDNS UCI configuration, service status and the dedicated read-only RPC helper.
• The app has been tested with the source-built agent on OpenWrt 24.10 and 25.12 snapshots.

[openwrt-ai]

Reviewed 1 new commit; see inline comments. The commit message matches its changes, and the backend dependency on 51ddns-agent (openwrt/packages#30158) is already called out in the PR description, so I did not flag it as a missing consumer.

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Generated by Claude Code

[openwrt-ai]

The hand-rolled json_escape only escapes \ and ". Any control character in the agent's --version output — a tab, a CR from a \r\n line ending, a backspace — is emitted raw into the string and produces invalid JSON, which makes the whole info ubus call fail rather than just showing a mangled version string. head -n 1 strips the LF but not a trailing CR.

Other rpcd helpers in this repo use jshn for exactly this reason, e.g. luci.squid and olsrvizinfo.

Suggested change

	info)
	version="$(/usr/bin/51ddns-agent --version 2>/dev/null | head -n 1)"
	printf '{"version":"%s"}\n' "$(json_escape "$version")"
	;;
	info)
	version="$(/usr/bin/51ddns-agent --version 2>/dev/null | head -n 1)"
	json_init
	json_add_string version "$version"
	json_dump
	;;

This also needs . /usr/share/libubox/jshn.sh near the top of the file, and the json_escape helper on lines 3-5 can then be dropped.

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Generated by Claude Code

[openwrt-ai]

status relays the whole of /var/lib/51ddns/status.json verbatim as the ubus reply, but the view only consumes plan.product_name and plan.expires_at. Two consequences worth confirming:

1. Everything the agent happens to write into that file becomes readable by any session holding the luci-app-51ddns read ACL. Can status.json contain the account token, a device secret or a relay credential? If so, this widens the exposure well beyond what the page needs — emitting only the fields the view reads (online, plan.product_name, plan.expires_at) would keep the ACL honest.
2. The file is passed through without any validation, so if the agent rewrites it non-atomically a partial read is returned as the ubus payload and the call fails to parse instead of falling back to {"online":false}.

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Generated by Claude Code

[openwrt-ai]

nit: these two strings are count-dependent, so translators into languages with more than two plural forms can't render them correctly through _(). luci-base exposes N_(n, singular, plural) for this (see nftables.js:401),`` and it is already whitelisted as a global in eslint.config.mjs.

Suggested change

	const hours = Math.ceil(milliseconds / 3600000);
	const label = hours > 48
	? _('About %d days').format(Math.ceil(hours / 24))
	: _('%d hours').format(hours);
	const hours = Math.ceil(milliseconds / 3600000);
	const days = Math.ceil(hours / 24);
	const label = hours > 48
	? N_(days, 'About %d day', 'About %d days').format(days)
	: N_(hours, '%d hour', '%d hours').format(hours);

The .pot template needs regenerating afterwards so the entries pick up their msgid_plural form.

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Generated by Claude Code

[openwrt-ai]

nit: anonymous is only consulted by TypedSection/GridSection; NamedSection never reads it, so line 97 has no effect.

Suggested change

	const section = map.section(form.NamedSection, 'main', 'agent', _('Quick setup'));
	section.anonymous = true;
	section.addremove = false;
	const section = map.section(form.NamedSection, 'main', 'agent', _('Quick setup'));
	section.addremove = false;

Separately: with addremove = false this page can only edit a pre-existing config agent 'main' section — if /etc/config/51ddns is missing or has no such section the form renders empty and the user has no way to enter the token. This package ships no root/etc/config/51ddns, so I assume 51ddns-agent provides it with that exact section name; can you confirm that's the case in openwrt/packages#30158?

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Generated by Claude Code

[openwrt-ai]

nit: "About %d days" sorts before "Account token", so this template can't have come out of the in-tree scanner — it pipes everything through msguniq -s, which emits msgids in strict byte order. Please regenerate the template with the repo's i18n scanner rather than hand-maintaining it, otherwise the next automated refresh will churn this file.

Suggested change

	#: applications/luci-app-51ddns/htdocs/luci-static/resources/view/51ddns/overview.js:133
	msgid "Account token"
	msgstr ""
	#: applications/luci-app-51ddns/htdocs/luci-static/resources/view/51ddns/overview.js:105
	msgid "Agent version"
	msgstr ""
	#: applications/luci-app-51ddns/htdocs/luci-static/resources/view/51ddns/overview.js:64
	msgid "About %d days"
	msgstr ""
	#: applications/luci-app-51ddns/htdocs/luci-static/resources/view/51ddns/overview.js:64
	msgid "About %d days"
	msgstr ""
	#: applications/luci-app-51ddns/htdocs/luci-static/resources/view/51ddns/overview.js:133
	msgid "Account token"
	msgstr ""
	#: applications/luci-app-51ddns/htdocs/luci-static/resources/view/51ddns/overview.js:105
	msgid "Agent version"
	msgstr ""

(If you take the N_() change suggested on overview.js, ignore this hunk and just regenerate — the entries change shape anyway.)

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Generated by Claude Code