feat(config): add `maximum.supported.desktop.version`

Signed-off-by: skjnldsv <skjnldsv@protonmail.com>

apps/dav/lib/Connector/Sabre/BlockLegacyClientPlugin.php

@@ -49,14 +49,26 @@ class BlockLegacyClientPlugin extends ServerPlugin {
 			return;
 		}
 
-		$minimumSupportedDesktopVersion = $this->config->getSystemValue('minimum.supported.desktop.version', '2.3.0');
+		$minimumSupportedDesktopVersion = $this->config->getSystemValueString('minimum.supported.desktop.version', '2.3.0');
+		$maximumSupportedDesktopVersion = $this->config->getSystemValueString('maximum.supported.desktop.version', '99.99.99');
+
+		// Check if the client is a desktop client
 		preg_match(IRequest::USER_AGENT_CLIENT_DESKTOP, $userAgent, $versionMatches);
-		if (isset($versionMatches[1]) &&
-			version_compare($versionMatches[1], $minimumSupportedDesktopVersion) === -1) {
+
+		// If the client is a desktop client and the version is too old, block it
+		if (isset($versionMatches[1]) && version_compare($versionMatches[1], $minimumSupportedDesktopVersion) === -1) {
 			$customClientDesktopLink = htmlspecialchars($this->themingDefaults->getSyncClientUrl());
 			$minimumSupportedDesktopVersion = htmlspecialchars($minimumSupportedDesktopVersion);
 
 			throw new \Sabre\DAV\Exception\Forbidden("This version of the client is unsupported. Upgrade to <a href=\"$customClientDesktopLink\">version $minimumSupportedDesktopVersion or later</a>.");
 		}
+
+		// If the client is a desktop client and the version is too new, block it
+		if (isset($versionMatches[1]) && version_compare($versionMatches[1], $maximumSupportedDesktopVersion) === 1) {
+			$customClientDesktopLink = htmlspecialchars($this->themingDefaults->getSyncClientUrl());
+			$maximumSupportedDesktopVersion = htmlspecialchars($maximumSupportedDesktopVersion);
+
+			throw new \Sabre\DAV\Exception\Forbidden("This version of the client is unsupported. Downgrade to <a href=\"$customClientDesktopLink\">version $maximumSupportedDesktopVersion or earlier</a>.");
+		}
 	}
 }

apps/dav/tests/unit/Connector/Sabre/BlockLegacyClientPluginTest.php

@@ -16,6 +16,12 @@ use PHPUnit\Framework\MockObject\MockObject;
 use Sabre\HTTP\RequestInterface;
 use Test\TestCase;
 
+enum ERROR_TYPE {
+	case MIN_ERROR;
+	case MAX_ERROR;
+	case NONE;
+}
+
 /**
  * Class BlockLegacyClientPluginTest
  *
@@ -40,29 +46,41 @@ class BlockLegacyClientPluginTest extends TestCase {
 
 	public static function oldDesktopClientProvider(): array {
 		return [
-			['Mozilla/5.0 (Windows) mirall/1.5.0'],
-			['Mozilla/5.0 (Bogus Text) mirall/1.6.9'],
+			['Mozilla/5.0 (Windows) mirall/1.5.0', ERROR_TYPE::MIN_ERROR],
+			['Mozilla/5.0 (Bogus Text) mirall/1.6.9', ERROR_TYPE::MIN_ERROR],
+			['Mozilla/5.0 (Windows) mirall/2.5.0', ERROR_TYPE::MAX_ERROR],
+			['Mozilla/5.0 (Bogus Text) mirall/2.0.1', ERROR_TYPE::MAX_ERROR],
+			['Mozilla/5.0 (Windows) mirall/2.0.0', ERROR_TYPE::NONE],
+			['Mozilla/5.0 (Bogus Text) mirall/2.0.0', ERROR_TYPE::NONE],
 		];
 	}
 
 	/**
 	 * @dataProvider oldDesktopClientProvider
 	 */
-	public function testBeforeHandlerException(string $userAgent): void {
-		$this->expectException(\Sabre\DAV\Exception\Forbidden::class);
-
+	public function testBeforeHandlerException(string $userAgent, ERROR_TYPE $errorType): void {
 		$this->themingDefaults
-			->expects($this->once())
+			->expects($this->atMost(1))
 			->method('getSyncClientUrl')
 			->willReturn('https://nextcloud.com/install/#install-clients');
 
 		$this->config
-			->expects($this->once())
-			->method('getSystemValue')
-			->with('minimum.supported.desktop.version', '2.3.0')
-			->willReturn('1.7.0');
-
-		$this->expectExceptionMessage('This version of the client is unsupported. Upgrade to <a href="https://nextcloud.com/install/#install-clients">version 1.7.0 or later</a>.');
+			->expects($this->exactly(2))
+			->method('getSystemValueString')
+			->willReturnCallback(function (string $key) {
+				if ($key === 'minimum.supported.desktop.version') {
+					return '1.7.0';
+				}
+				return '2.0.0';
+			});
+
+		if ($errorType !== ERROR_TYPE::NONE) {
+			$errorString = $errorType === ERROR_TYPE::MIN_ERROR
+			? 'This version of the client is unsupported. Upgrade to <a href="https://nextcloud.com/install/#install-clients">version 1.7.0 or later</a>.'
+			: 'This version of the client is unsupported. Downgrade to <a href="https://nextcloud.com/install/#install-clients">version 2.0.0 or earlier</a>.';
+			$this->expectException(\Sabre\DAV\Exception\Forbidden::class);
+			$this->expectExceptionMessage($errorString);
+		}
 
 		/** @var RequestInterface|MockObject $request */
 		$request = $this->createMock('\Sabre\HTTP\RequestInterface');
@@ -72,7 +90,6 @@ class BlockLegacyClientPluginTest extends TestCase {
 			->with('User-Agent')
 			->willReturn($userAgent);
 
-
 		$this->blockLegacyClientVersionPlugin->beforeHandler($request);
 	}
 
@@ -80,21 +97,28 @@ class BlockLegacyClientPluginTest extends TestCase {
 	 * Ensure that there is no room for XSS attack through configured URL / version
 	 * @dataProvider oldDesktopClientProvider
 	 */
-	public function testBeforeHandlerExceptionPreventXSSAttack(string $userAgent): void {
+	public function testBeforeHandlerExceptionPreventXSSAttack(string $userAgent, ERROR_TYPE $errorType): void {
 		$this->expectException(\Sabre\DAV\Exception\Forbidden::class);
 
 		$this->themingDefaults
-			->expects($this->once())
+			->expects($this->atMost(1))
 			->method('getSyncClientUrl')
 			->willReturn('https://example.com"><script>alter("hacked");</script>');
 
 		$this->config
-			->expects($this->once())
-			->method('getSystemValue')
-			->with('minimum.supported.desktop.version', '2.3.0')
-			->willReturn('1.7.0 <script>alert("unsafe")</script>');
-
-		$this->expectExceptionMessage('This version of the client is unsupported. Upgrade to <a href="https://example.com&quot;&gt;&lt;script&gt;alter(&quot;hacked&quot;);&lt;/script&gt;">version 1.7.0 &lt;script&gt;alert(&quot;unsafe&quot;)&lt;/script&gt; or later</a>.');
+			->expects($this->exactly(2))
+			->method('getSystemValueString')
+			->willReturnCallback(function (string $key) {
+				if ($key === 'minimum.supported.desktop.version') {
+					return '1.7.0 <script>alert("unsafe")</script>';
+				}
+				return '2.0.0 <script>alert("unsafe")</script>';
+			});
+
+		$errorString = $errorType === ERROR_TYPE::MIN_ERROR
+			? 'This version of the client is unsupported. Upgrade to <a href="https://example.com&quot;&gt;&lt;script&gt;alter(&quot;hacked&quot;);&lt;/script&gt;">version 1.7.0 &lt;script&gt;alert(&quot;unsafe&quot;)&lt;/script&gt; or later</a>.'
+			: 'This version of the client is unsupported. Downgrade to <a href="https://example.com&quot;&gt;&lt;script&gt;alter(&quot;hacked&quot;);&lt;/script&gt;">version 2.0.0 &lt;script&gt;alert(&quot;unsafe&quot;)&lt;/script&gt; or earlier</a>.';
+		$this->expectExceptionMessage($errorString);
 
 		/** @var RequestInterface|MockObject $request */
 		$request = $this->createMock('\Sabre\HTTP\RequestInterface');
@@ -104,15 +128,17 @@ class BlockLegacyClientPluginTest extends TestCase {
 			->with('User-Agent')
 			->willReturn($userAgent);
 
-
 		$this->blockLegacyClientVersionPlugin->beforeHandler($request);
 	}
 
-	public function newAndAlternateDesktopClientProvider(): array {
+	public static function newAndAlternateDesktopClientProvider(): array {
 		return [
 			['Mozilla/5.0 (Windows) mirall/1.7.0'],
 			['Mozilla/5.0 (Bogus Text) mirall/1.9.3'],
 			['Mozilla/5.0 (Not Our Client But Old Version) LegacySync/1.1.0'],
+			['Mozilla/5.0 (Windows) mirall/4.7.0'],
+			['Mozilla/5.0 (Bogus Text) mirall/3.9.3'],
+			['Mozilla/5.0 (Not Our Client But Old Version) LegacySync/45.0.0'],
 		];
 	}
 
@@ -129,10 +155,14 @@ class BlockLegacyClientPluginTest extends TestCase {
 			->willReturn($userAgent);
 
 		$this->config
-			->expects($this->once())
-			->method('getSystemValue')
-			->with('minimum.supported.desktop.version', '2.3.0')
-			->willReturn('1.7.0');
+			->expects($this->exactly(2))
+			->method('getSystemValueString')
+			->willReturnCallback(function (string $key) {
+				if ($key === 'minimum.supported.desktop.version') {
+					return '1.7.0';
+				}
+				return '10.0.0';
+			});
 
 		$this->blockLegacyClientVersionPlugin->beforeHandler($request);
 	}
@@ -145,6 +175,7 @@ class BlockLegacyClientPluginTest extends TestCase {
 			->method('getHeader')
 			->with('User-Agent')
 			->willReturn(null);
+
 		$this->blockLegacyClientVersionPlugin->beforeHandler($request);
 	}
 }

config/config.sample.php

@@ -2136,6 +2136,15 @@ $CONFIG = [
  */
 'minimum.supported.desktop.version' => '2.3.0',
 
+/**
+ * The maximum Nextcloud desktop client version that will be allowed to sync with
+ * this server instance. All connections made from later clients will be denied
+ * by the server.
+ *
+ * Defaults to 99.99.99
+ */
+'maximum.supported.desktop.version' => '99.99.99',
+
 /**
  * Option to allow local storage to contain symlinks.
  * WARNING: Not recommended. This would make it possible for Nextcloud to access