do not flip available state to unavailable, allow empty results

- the detection relies that the first, requested result is not empty
- it might be empty though – groups without members
- protect switching from available to unavailable
  - switching the other way around was also not envisaged either

Signed-off-by: Arthur Schiwon <blizzz@arthur-schiwon.de>

apps/user_ldap/lib/Connection.php

@@ -72,6 +72,7 @@ use OCP\ILogger;
  * @property string ldapGidNumber
  * @property int hasMemberOfFilterSupport
  * @property int useMemberOfToDetectMembership
+ * @property string ldapMatchingRuleInChainState
  */
 class Connection extends LDAPUtility {
 	private $ldapConnectionRes = null;

apps/user_ldap/lib/Group_LDAP.php

@@ -254,21 +254,27 @@ class Group_LDAP extends BackendUtility implements GroupInterface, IGroupLDAP, I
 		) {
 			$attemptedLdapMatchingRuleInChain = true;
 			// compatibility hack with servers supporting :1.2.840.113556.1.4.1941:, and others)
-			$filter = $this->access->combineFilterWithAnd([$this->access->connection->ldapUserFilter, 'memberof:1.2.840.113556.1.4.1941:=' . $dnGroup]);
+			$filter = $this->access->combineFilterWithAnd([
+				$this->access->connection->ldapUserFilter,
+				$this->access->connection->ldapUserDisplayName . '=*',
+				'memberof:1.2.840.113556.1.4.1941:=' . $dnGroup
+			]);
 			$memberRecords = $this->access->fetchListOfUsers(
 				$filter,
 				$this->access->userManager->getAttributes(true)
 			);
-			if (!empty($memberRecords)) {
-				if ($this->access->connection->ldapMatchingRuleInChainState === Configuration::LDAP_SERVER_FEATURE_UNKNOWN) {
-					$this->access->connection->ldapMatchingRuleInChainState = Configuration::LDAP_SERVER_FEATURE_AVAILABLE;
-					$this->access->connection->saveConfiguration();
-				}
-				return array_reduce($memberRecords, function ($carry, $record) {
-					$carry[] = $record['dn'][0];
-					return $carry;
-				}, []);
+			$result = array_reduce($memberRecords, function ($carry, $record) {
+				$carry[] = $record['dn'][0];
+				return $carry;
+			}, []);
+			if ($this->access->connection->ldapMatchingRuleInChainState === Configuration::LDAP_SERVER_FEATURE_AVAILABLE) {
+				return $result;
+			} elseif (!empty($memberRecords)) {
+				$this->access->connection->ldapMatchingRuleInChainState = Configuration::LDAP_SERVER_FEATURE_AVAILABLE;
+				$this->access->connection->saveConfiguration();
+				return $result;
 			}
+			// when feature availability is unknown, and the result is empty, continue and test with original approach
 		}
 
 		$seen[$dnGroup] = 1;
@@ -283,7 +289,10 @@ class Group_LDAP extends BackendUtility implements GroupInterface, IGroupLDAP, I
 		$allMembers += $this->getDynamicGroupMembers($dnGroup);
 
 		$this->access->connection->writeToCache($cacheKey, $allMembers);
-		if (isset($attemptedLdapMatchingRuleInChain) && !empty($allMembers)) {
+		if (isset($attemptedLdapMatchingRuleInChain)
+			&& $this->access->connection->ldapMatchingRuleInChainState === Configuration::LDAP_SERVER_FEATURE_UNKNOWN
+			&& !empty($allMembers)
+		) {
 			$this->access->connection->ldapMatchingRuleInChainState = Configuration::LDAP_SERVER_FEATURE_UNAVAILABLE;
 			$this->access->connection->saveConfiguration();
 		}

apps/user_ldap/tests/Group_LDAPTest.php

@@ -129,6 +129,10 @@ class Group_LDAPTest extends TestCase {
 			->method('countUsers')
 			->willReturn(2);
 
+		$access->userManager->expects($this->any())
+			->method('getAttributes')
+			->willReturn(['displayName', 'mail']);
+
 		$groupBackend = new GroupLDAP($access, $pluginManager);
 		$users = $groupBackend->countUsersInGroup('group');
 
@@ -172,6 +176,10 @@ class Group_LDAPTest extends TestCase {
 			->method('escapeFilterPart')
 			->willReturnArgument(0);
 
+		$access->userManager->expects($this->any())
+			->method('getAttributes')
+			->willReturn(['displayName', 'mail']);
+
 		$groupBackend = new GroupLDAP($access, $pluginManager);
 		$users = $groupBackend->countUsersInGroup('group', '3');
 
@@ -546,7 +554,10 @@ class Group_LDAPTest extends TestCase {
 		$access->expects($this->any())
 			->method('combineFilterWithAnd')
 			->willReturn('pseudo=filter');
-		$access->userManager = $this->createMock(Manager::class);
+
+		$access->userManager->expects($this->any())
+			->method('getAttributes')
+			->willReturn(['displayName', 'mail']);
 
 		$groupBackend = new GroupLDAP($access, $pluginManager);
 		$users = $groupBackend->usersInGroup('foobar');
@@ -587,7 +598,10 @@ class Group_LDAPTest extends TestCase {
 		$access->expects($this->any())
 			->method('combineFilterWithAnd')
 			->willReturn('pseudo=filter');
-		$access->userManager = $this->createMock(Manager::class);
+
+		$access->userManager->expects($this->any())
+			->method('getAttributes')
+			->willReturn(['displayName', 'mail']);
 
 		$groupBackend = new GroupLDAP($access, $pluginManager);
 		$users = $groupBackend->usersInGroup('foobar');
@@ -627,6 +641,10 @@ class Group_LDAPTest extends TestCase {
 			->method('isDNPartOfBase')
 			->willReturn(true);
 
+		$access->userManager->expects($this->any())
+			->method('getAttributes')
+			->willReturn(['displayName', 'mail']);
+
 		$groupBackend = new GroupLDAP($access, $pluginManager);
 		$users = $groupBackend->countUsersInGroup('foobar');