feat: reintroduce missing local dns override (fixes #236)

app/routes/dns/components/manage-ns.tsx

@@ -1,16 +1,24 @@
-import { Form } from 'react-router';
+import { Info } from 'lucide-react';
+import { Form, useSubmit } from 'react-router';
 import Button from '~/components/Button';
 import Link from '~/components/Link';
+import Switch from '~/components/Switch';
 import TableList from '~/components/TableList';
+import Tooltip from '~/components/Tooltip';
 import cn from '~/utils/cn';
 import AddNS from '../dialogs/add-ns';
 
 interface Props {
 	nameservers: Record<string, string[]>;
+	overrideLocalDns: boolean;
 	isDisabled: boolean;
 }
 
-export default function ManageNS({ nameservers, isDisabled }: Props) {
+export default function ManageNS({
+	nameservers,
+	isDisabled,
+	overrideLocalDns,
+}: Props) {
 	return (
 		<div className="flex flex-col w-2/3">
 			<h1 className="text-2xl font-medium mb-4">Nameservers</h1>
@@ -31,6 +39,7 @@ export default function ManageNS({ nameservers, isDisabled }: Props) {
 						isGlobal={key === 'global'}
 						isDisabled={isDisabled}
 						nameservers={nameservers}
+						overrideLocalDns={overrideLocalDns}
 						name={key}
 					/>
 				))}
@@ -45,6 +54,7 @@ interface ListProps {
 	isGlobal: boolean;
 	isDisabled: boolean;
 	nameservers: Record<string, string[]>;
+	overrideLocalDns: boolean;
 	name: string;
 }
 
@@ -52,6 +62,7 @@ function NameserverList({
 	isGlobal,
 	isDisabled,
 	nameservers,
+	overrideLocalDns,
 	name,
 }: ListProps) {
 	const list = isGlobal ? nameservers.global : nameservers[name];
@@ -59,12 +70,54 @@ function NameserverList({
 		return null;
 	}
 
+	const submit = useSubmit();
 	return (
 		<div className="mb-8">
 			<div className="flex items-center justify-between mb-2">
-				<h2 className="text-md font-medium opacity-80">
-					{isGlobal ? 'Global Nameservers' : name}
-				</h2>
+				{isGlobal ? (
+					<div className="flex items-center justify-between w-full">
+						<h2 className="text-md font-medium opacity-80">
+							Global Nameservers
+						</h2>
+						<div className="flex items-center gap-2 text-sm">
+							<Tooltip>
+								<Info className="size-4" />
+								<Tooltip.Body>
+									When enabled, use the DNS servers listed below to resolve
+									names outside the tailnet. When disabled (default), devices
+									will prefer their local DNS configuration.
+									<Link
+										to="https://tailscale.com/kb/1054/dns#global-nameservers"
+										name="Tailscale Global Nameservers Documentation"
+									>
+										Learn More
+									</Link>
+								</Tooltip.Body>
+							</Tooltip>
+							<p>Override DNS servers</p>
+							<Switch
+								label="Override local DNS settings"
+								className="h-[15px] w-[23px] p-[2px]"
+								switchClassName="h-[9px] w-[9px]"
+								name="override_dns"
+								defaultSelected={overrideLocalDns}
+								onChange={(v) => {
+									submit(
+										{
+											action_id: 'override_dns',
+											override_dns: v ? 'true' : 'false',
+										},
+										{
+											method: 'POST',
+										},
+									);
+								}}
+							/>
+						</div>
+					</div>
+				) : (
+					<h2 className="text-md font-medium opacity-80">{name}</h2>
+				)}
 			</div>
 			<TableList>
 				{list.length > 0