[locationinfo] Add error log for backends

14 files changed, 183 insertions, 92 deletions

diff --git a/modules-available/locationinfo/api.inc.php b/modules-available/locationinfo/api.inc.php
index 9ebbcea6..c44ec72d 100644
--- a/modules-available/locationinfo/api.inc.php
+++ b/modules-available/locationinfo/api.inc.php
@@ -204,7 +204,7 @@ function getCalendar($idList)
 			$calendarFromBackend = array();
 		}
 
-		LocationInfo::setServerError($serverid, $serverInstance->getError());
+		LocationInfo::setServerError($serverid, $serverInstance->getErrors());
 
 		if (is_array($calendarFromBackend)) {
 			foreach ($calendarFromBackend as $key => $value) {
diff --git a/modules-available/locationinfo/inc/coursebackend.inc.php b/modules-available/locationinfo/inc/coursebackend.inc.php
index 68a0e09b..bc5b059e 100644
--- a/modules-available/locationinfo/inc/coursebackend.inc.php
+++ b/modules-available/locationinfo/inc/coursebackend.inc.php
@@ -15,9 +15,13 @@ abstract class CourseBackend
 	 */
 	private static $backendTypes = false;
 	/**
-	 * @var boolean|string false = no error, error message otherwise
+	 * @var boolean|string legacy, do not use
 	 */
-	protected $error;
+	protected $error = false;
+	/**
+	 * @var array list of errors that occured, fill using addError()
+	 */
+	private $errors;
 	/**
 	 * @var int as internal serverId
 	 */
@@ -32,7 +36,12 @@ abstract class CourseBackend
 	 */
 	public final function __construct()
 	{
-		$this->error = false;
+		$this->errors = [];
+	}
+
+	protected final function addError($message, $fatal)
+	{
+		$this->errors[] = ['time' => time(), 'message' => $message, 'fatal' => $fatal];
 	}
 
 	/**
@@ -156,13 +165,13 @@ abstract class CourseBackend
 	/**
 	 * Method for fetching the schedule of the given rooms on a server.
 	 *
-	 * @param array $roomId array of room ID to fetch
+	 * @param array $requestedLocationIds array of room ID to fetch
 	 * @return array|bool array containing the timetables as value and roomid as key as result, or false on error
 	 */
 	public final function fetchSchedule($requestedLocationIds)
 	{
 		if (!is_array($requestedLocationIds)) {
-			$this->error = 'No array of roomids was given to fetchSchedule';
+			$this->addError('No array of roomids was given to fetchSchedule', false);
 			return false;
 		}
 		if (empty($requestedLocationIds))
@@ -286,10 +295,19 @@ abstract class CourseBackend
 	 */
 	public final function getError()
 	{
+		trigger_error('getError() is legacy; use getErrors()');
 		return $this->error;
 	}
 
 	/**
+	 * @return array list of errors that occured during processing.
+	 */
+	public final function getErrors()
+	{
+		return $this->errors;
+	}
+
+	/**
 	 * Query path in array-representation of XML document.
 	 * e.g. 'path/syntax/foo/wanteditem'
 	 * This works for intermediate nodes (that have more children)
@@ -349,13 +367,13 @@ abstract class CourseBackend
 	 * @param string $response xml document to convert
 	 * @return bool|array array representation of the xml if possible, false otherwise
 	 */
-	protected function xmlStringToArray($response)
+	protected function xmlStringToArray($response, &$error)
 	{
 		$cleanresponse = preg_replace('/(<\/?)(\w+):([^>]*>)/', '$1$2$3', $response);
 		try {
 			$xml = @new SimpleXMLElement($cleanresponse); // This spams before throwing exception
 		} catch (Exception $e) {
-			$this->error = 'Could not parse reply as XML, got ' . get_class($e) . ': ' . $e->getMessage();
+			$error = get_class($e) . ': ' . $e->getMessage();
 			if (CONFIG_DEBUG) {
 				error_log($cleanresponse);
 			}
diff --git a/modules-available/locationinfo/inc/coursebackend/coursebackend_davinci.inc.php b/modules-available/locationinfo/inc/coursebackend/coursebackend_davinci.inc.php
index ed3d7ec2..2b2b9d00 100644
--- a/modules-available/locationinfo/inc/coursebackend/coursebackend_davinci.inc.php
+++ b/modules-available/locationinfo/inc/coursebackend/coursebackend_davinci.inc.php
@@ -14,7 +14,7 @@ class CourseBackend_Davinci extends CourseBackend
 	public function setCredentialsInternal($data)
 	{
 		if (empty($data['baseUrl'])) {
-			$this->error = "No url is given";
+			$this->addError("No url is given", true);
 			return false;
 		}
 		$location = preg_replace('#/+(davinciis\.dll)?\W*$#i', '', $data['baseUrl']);
@@ -27,16 +27,17 @@ class CourseBackend_Davinci extends CourseBackend
 	public function checkConnection()
 	{
 		if (empty($this->location)) {
-			$this->error = "Credentials are not set";
-		} else {
-			$startDate = new DateTime('today 0:00');
-			$endDate = new DateTime('+7 days 0:00');
-			$data = $this->fetchRoomRaw('someroomid123', $startDate, $endDate);
-			if ($data !== false && strpos($data, 'DAVINCI SERVER') === false) {
-				$this->error = "Unknown reply; this doesn't seem to be a DAVINCI server.";
-			}
+			$this->addError("Credentials are not set", true);
+			return false;
+		}
+		$startDate = new DateTime('today 0:00');
+		$endDate = new DateTime('+7 days 0:00');
+		$data = $this->fetchRoomRaw('someroomid123', $startDate, $endDate);
+		if ($data !== false && strpos($data, 'DAVINCI SERVER') === false) {
+			$this->addError("Unknown reply; this doesn't seem to be a DAVINCI server.", true);
+			return false;
 		}
-		return $this->error === false;
+		return true;
 	}
 
 	public function getCredentialDefinitions()
@@ -87,11 +88,8 @@ class CourseBackend_Davinci extends CourseBackend
 		curl_setopt_array($this->curlHandle, $options);
 		$output = curl_exec($this->curlHandle);
 		if ($output === false) {
-			$this->error = 'Curl error: ' . curl_error($this->curlHandle);
+			$this->addError('Curl error: ' . curl_error($this->curlHandle), true);
 			return false;
-		} else {
-			$this->error = false;
-			///Operation completed successfully
 		}
 		return $output;
 
@@ -109,22 +107,20 @@ class CourseBackend_Davinci extends CourseBackend
 			if ($return === false) {
 				continue;
 			}
-			$return = $this->xmlStringToArray($return);
+			$return = $this->xmlStringToArray($return, $err);
 			if ($return === false) {
-				if (CONFIG_DEBUG) {
-					error_log('Room was ' . $roomId);
-				}
+				$this->addError("Parsing room $roomId XML: $err", false);
 				continue;
 			}
 			$lessons = $this->getArrayPath($return, '/Lessons/Lesson');
 			if ($lessons === false) {
-				$this->error = "Cannot find /Lessons/Lesson in XML";
+				$this->addError("Cannot find /Lessons/Lesson in XML", false);
 				continue;
 			}
 			$timetable = [];
 			foreach ($lessons as $lesson) {
 				if (!isset($lesson['Date']) || !isset($lesson['Start']) || !isset($lesson['Finish'])) {
-					$this->error = 'Lesson is missing Date, Start or Finish';
+					$this->addError('Lesson is missing Date, Start or Finish', false);
 					continue;
 				}
 				$c = (int)$lesson['Date'];
diff --git a/modules-available/locationinfo/inc/coursebackend/coursebackend_dummy.inc.php b/modules-available/locationinfo/inc/coursebackend/coursebackend_dummy.inc.php
index 94c967de..5807a4ff 100644
--- a/modules-available/locationinfo/inc/coursebackend/coursebackend_dummy.inc.php
+++ b/modules-available/locationinfo/inc/coursebackend/coursebackend_dummy.inc.php
@@ -21,12 +21,10 @@ class CourseBackend_Dummy extends CourseBackend
 		$this->pw = $x['password'];
 
 		if ($this->pw === "mfg") {
-			$this->error = false;
 			return true;
-		} else {
-			$this->error = "USE mfg as password!";
-			return false;
 		}
+		$this->addError("USE mfg as password!", true);
+		return false;
 	}
 
 	/**
@@ -35,12 +33,10 @@ class CourseBackend_Dummy extends CourseBackend
 	public function checkConnection()
 	{
 		if ($this->pw == "mfg") {
-			$this->error = false;
 			return true;
-		} else {
-			$this->error = "USE mfg as password!";
-			return false;
 		}
+		$this->addError("USE mfg as password!", true);
+		return false;
 	}
 
 	/**
diff --git a/modules-available/locationinfo/inc/coursebackend/coursebackend_exchange.inc.php b/modules-available/locationinfo/inc/coursebackend/coursebackend_exchange.inc.php
index 1623755f..c61c3f2f 100755
--- a/modules-available/locationinfo/inc/coursebackend/coursebackend_exchange.inc.php
+++ b/modules-available/locationinfo/inc/coursebackend/coursebackend_exchange.inc.php
@@ -82,7 +82,7 @@ class CourseBackend_Exchange extends CourseBackend
 		try {
 			$response = $client->ResolveNames($request);
 		} catch (Exception $e) {
-			$this->error = $e->getMessage();
+			$this->addError($e->getMessage(), true);
 			return false;
 		}
 
@@ -92,7 +92,7 @@ class CourseBackend_Exchange extends CourseBackend
 				return !empty($mailadress);
 			}
 		} catch (Exception $e) {
-			$this->error = $e->getMessage();
+			$this->addError($e->getMessage(), true);
 		}
 		return false;
 	}
@@ -108,13 +108,13 @@ class CourseBackend_Exchange extends CourseBackend
 	{
 		foreach (['username', 'password'] as $field) {
 			if (empty($data[$field])) {
-				$this->error = 'setCredentials: Missing field ' . $field;
+				$this->addError('setCredentials: Missing field ' . $field, true);
 				return false;
 			}
 		}
 
 		if (empty($data['serverAddress'])) {
-			$this->error = "No url is given";
+			$this->addError("No url is given", true);
 			return false;
 		}
 
@@ -166,7 +166,7 @@ class CourseBackend_Exchange extends CourseBackend
 			try {
 				$items = $this->findEventsForRoom($client, $startDate, $endDate, $roomId);
 			} catch (Exception $e) {
-				$this->error .= "Failed to search for events for room $roomId: '{$e->getMessage()}'\n";
+				$this->addError("Failed to search for events for room $roomId: '{$e->getMessage()}'", true);
 				continue;
 			}
 
@@ -216,7 +216,7 @@ class CourseBackend_Exchange extends CourseBackend
 			if ($response_message->ResponseClass !== ResponseClassType::SUCCESS) {
 				$code = $response_message->ResponseCode;
 				$message = $response_message->MessageText;
-				$this->error .= "Failed to search for events for room $roomAddress: '$code: $message'\n";
+				$this->addError("Failed to search for events for room $roomAddress: '$code: $message'", true);
 				continue;
 			}
 			$items = array_merge($items, $response_message->RootFolder->Items->CalendarItem);
diff --git a/modules-available/locationinfo/inc/coursebackend/coursebackend_hisinone.inc.php b/modules-available/locationinfo/inc/coursebackend/coursebackend_hisinone.inc.php
index 2ffb9f41..809634ad 100644
--- a/modules-available/locationinfo/inc/coursebackend/coursebackend_hisinone.inc.php
+++ b/modules-available/locationinfo/inc/coursebackend/coursebackend_hisinone.inc.php
@@ -20,17 +20,16 @@ class CourseBackend_HisInOne extends CourseBackend
 			// If not using OpenCourseService, require credentials
 			foreach (['username', 'password'] as $field) {
 				if (empty($data[$field])) {
-					$this->error = 'setCredentials: Missing field ' . $field;
+					$this->addError('setCredentials: Missing field ' . $field, true);
 					return false;
 				}
 			}
 		}
 		if (empty($data['baseUrl'])) {
-			$this->error = "No url is given";
+			$this->addError("No url is given", true);
 			return false;
 		}
 
-		$this->error = false;
 		$this->username = $data['username'];
 		if (!empty($data['role'])) {
 			$this->username .= "\t" . $data['role'];
@@ -65,11 +64,10 @@ class CourseBackend_HisInOne extends CourseBackend
 	public function checkConnection()
 	{
 		if (empty($this->location)) {
-			$this->error = "Credentials are not set";
-		} else {
-			$this->findUnit(123456789, date('Y-m-d'), true);
+			$this->addError("Credentials are not set", true);
+			return false;
 		}
-		return $this->error === false;
+		return $this->findUnit(123456789, date('Y-m-d'), true) !== false;
 	}
 
 	/**
@@ -100,22 +98,21 @@ class CourseBackend_HisInOne extends CourseBackend
 
 		$soap_request = $doc->saveXML();
 		$response1 = $this->postToServer($soap_request, "findUnit");
-		if ($this->error !== false) {
+		if ($response1 === false) {
+			$this->addError('Could not fetch room ' . $roomId, true);
 			return false;
 		}
-		$response2 = $this->xmlStringToArray($response1);
+		$response2 = $this->xmlStringToArray($response1, $err);
 		if (!is_array($response2)) {
-			if ($this->error === false) {
-				$this->error = 'Cannot convert XML response to array';
-			}
+			$this->addError("Parsing room $roomId: $err", false);
 			return false;
 		}
 		if (!isset($response2['soapenvBody'])) {
-			$this->error = 'Backend reply is missing element soapenvBody';
+			$this->addError('Backend reply is missing element soapenvBody', true);
 			return false;
 		}
 		if (isset($response2['soapenvBody']['soapenvFault'])) {
-			$this->error = 'SOAP-Fault (' . $response2['soapenvBody']['soapenvFault']['faultcode'] . ") " . $response2['soapenvBody']['soapenvFault']['faultstring'];
+			$this->addError('SOAP-Fault (' . $response2['soapenvBody']['soapenvFault']['faultcode'] . ") " . $response2['soapenvBody']['soapenvFault']['faultstring'], true);
 			return false;
 		}
 		// We only need to check if the connection is working (URL ok, credentials ok, ..) so bail out early
@@ -131,7 +128,7 @@ class CourseBackend_HisInOne extends CourseBackend
 		}
 		$idSubDoc = $this->getArrayPath($response2, $path);
 		if ($idSubDoc === false) {
-			$this->error = 'Cannot find ' . $path;
+			$this->addError('Cannot find ' . $path, false);
 			//@file_put_contents('/tmp/findUnit-1.' . $roomId . '.' . microtime(true), print_r($response2, true));
 			return false;
 		}
@@ -139,7 +136,7 @@ class CourseBackend_HisInOne extends CourseBackend
 			return $idSubDoc;
 		$idList = $this->getArrayPath($idSubDoc, $subpath);
 		if ($idList === false) {
-			$this->error = 'Cannot find ' . $subpath . ' after ' . $path;
+			$this->addError('Cannot find ' . $subpath . ' after ' . $path, false);
 			@file_put_contents('/tmp/bwlp-findUnit-2.' . $roomId . '.' . microtime(true), print_r($idSubDoc, true));
 		}
 		return $idList;
@@ -201,10 +198,7 @@ class CourseBackend_HisInOne extends CourseBackend
 		$output = curl_exec($this->curlHandle);
 
 		if ($output === false) {
-			$this->error = 'Curl error: ' . curl_error($this->curlHandle);
-		} else {
-			$this->error = false;
-			///Operation completed successfully
+			$this->addError('Curl error: ' . curl_error($this->curlHandle), false);
 		}
 		return $output;
 	}
@@ -239,14 +233,8 @@ class CourseBackend_HisInOne extends CourseBackend
 			$ok = false;
 			foreach ($currentWeek as $day) {
 				$roomEventIds = $this->findUnit($roomId, $day, false);
-				if ($roomEventIds === false) {
-					if ($this->error !== false) {
-						error_log('Cannot findUnit(' . $roomId . '): ' . $this->error);
-						$this->error = false;
-					}
-					// TODO: Error gets swallowed
+				if ($roomEventIds === false)
 					continue;
-				}
 				$ok = true;
 				$eventIds = array_merge($eventIds, $roomEventIds);
 			}
@@ -262,12 +250,8 @@ class CourseBackend_HisInOne extends CourseBackend
 		//get all information on each event
 		foreach ($eventIds as $eventId) {
 			$event = $this->readUnit(intval($eventId));
-			if ($event === false) {
-				error_log('Cannot readUnit(' . $eventId . '): ' . $this->error);
-				$this->error = false;
-				// TODO: Error gets swallowed
+			if ($event === false)
 				continue;
-			}
 			$eventDetails = array_merge($eventDetails, $event);
 		}
 		$name = false;
@@ -286,9 +270,9 @@ class CourseBackend_HisInOne extends CourseBackend
 			}
 			$planElements = $this->getArrayPath($event, '/hisplanelements/hisplanelement');
 			if ($planElements === false) {
-				$this->error = 'Cannot find ./hisplanelements/hisplanelement';
-				error_log('Cannot find ./hisplanelements/hisplanelement');
-				error_log(print_r($event, true));
+				$this->addError('Cannot find ./hisplanelements/hisplanelement', false);
+				//error_log('Cannot find ./hisplanelements/hisplanelement');
+				//error_log(print_r($event, true));
 				continue;
 			}
 			foreach ($planElements as $planElement) {
@@ -308,9 +292,9 @@ class CourseBackend_HisInOne extends CourseBackend
 				$unitPlannedDates = $this->getArrayPath($planElement,
 					'/hisplannedDates/hisplannedDate/hisindividualDates/hisindividualDate');
 				if ($unitPlannedDates === false) {
-					$this->error = 'Cannot find ./hisplannedDates/hisplannedDate/hisindividualDates/hisindividualDate';
-					error_log('Cannot find ./hisplannedDates/hisplannedDate/hisindividualDates/hisindividualDate');
-					error_log(print_r($planElement, true));
+					$this->addError('Cannot find ./hisplannedDates/hisplannedDate/hisindividualDates/hisindividualDate', false);
+					//error_log('Cannot find ./hisplannedDates/hisplannedDate/hisindividualDates/hisindividualDate');
+					//error_log(print_r($planElement, true));
 					continue;
 				}
 				$localName = $this->getArrayPath($planElement, '/hisdefaulttext');
@@ -366,15 +350,17 @@ class CourseBackend_HisInOne extends CourseBackend
 		if ($response1 === false) {
 			return false;
 		}
-		$response2 = $this->xmlStringToArray($response1);
-		if ($response2 === false)
+		$response2 = $this->xmlStringToArray($response1, $err);
+		if ($response2 === false) {
+			$this->addError("Cannot parse unit $unit as XML: $err", false);
 			return false;
+		}
 		if (!isset($response2['soapenvBody'])) {
-			$this->error = 'Backend reply is missing element soapenvBody';
+			$this->addError('Backend reply is missing element soapenvBody', true);
 			return false;
 		}
 		if (isset($response2['soapenvBody']['soapenvFault'])) {
-			$this->error = 'SOAP-Fault (' . $response2['soapenvBody']['soapenvFault']['faultcode'] . ") " . $response2['soapenvBody']['soapenvFault']['faultstring'];
+			$this->addError('SOAP-Fault (' . $response2['soapenvBody']['soapenvFault']['faultcode'] . ") " . $response2['soapenvBody']['soapenvFault']['faultstring'], true);
 			return false;
 		}
 		return $this->getArrayPath($response2, '/soapenvBody/hisreadUnitResponse/hisunit');
diff --git a/modules-available/locationinfo/inc/locationinfo.inc.php b/modules-available/locationinfo/inc/locationinfo.inc.php
index 377e960b..6cc71b3e 100644
--- a/modules-available/locationinfo/inc/locationinfo.inc.php
+++ b/modules-available/locationinfo/inc/locationinfo.inc.php
@@ -46,10 +46,25 @@ class LocationInfo
 	 * Set current error message of given server. Pass null or false to clear.
 	 *
 	 * @param int $serverId id of server
-	 * @param string $message error message to set, null or false clears error.
+	 * @param string|array $message error message to set, array of error message struct, null or false clears error.
 	 */
 	public static function setServerError($serverId, $message)
 	{
+		if (is_array($message)) {
+			$fatal = false;
+			foreach ($message as $m) {
+				if ($m['fatal']) {
+					$fatal = $m['message'];
+				}
+				Database::exec('INSERT INTO locationinfo_backendlog (serverid, dateline, message)
+						VALUES (:sid, :dateline, :message)', [
+					'sid' => $serverId,
+					'dateline' => $m['time'],
+					'message' => ($m['fatal'] ? '[F]' : '[W]') . $m['message'],
+				]);
+			}
+			$message = $fatal;
+		}
 		if ($message === false || $message === null) {
 			Database::exec("UPDATE `locationinfo_coursebackend` SET error = NULL
 					WHERE serverid = :id", array('id' => $serverId));
diff --git a/modules-available/locationinfo/install.inc.php b/modules-available/locationinfo/install.inc.php
index fc02ed76..7e58315b 100644
--- a/modules-available/locationinfo/install.inc.php
+++ b/modules-available/locationinfo/install.inc.php
@@ -35,6 +35,16 @@ $t3 = $res[] = tableCreate('locationinfo_panel', "
 	KEY `panelname` (`panelname`)
 ");
 
+// 2019-03-06: Add logging table
+$res[] = tableCreate('locationinfo_backendlog', "
+	`logid` int(10) UNSIGNED NOT NULL AUTO_INCREMENT,
+	`serverid` int(10) UNSIGNED NOT NULL,
+	`dateline` int(10) UNSIGNED NOT NULL,
+	`message` varchar(500) NOT NULL,
+	PRIMARY KEY (`logid`),
+	KEY (`serverid`)
+");
+
 // Update
 
 if ($t1 === UPDATE_NOOP) {
@@ -89,6 +99,13 @@ if (!tableHasColumn('locationinfo_locationconfig', 'lastuse')) {
 	$res[] = UPDATE_DONE;
 }
 
+// 2019-03-06: Add logging table constraint
+if (tableGetConstraints('locationinfo_backendlog', 'serverid',
+		'locationinfo_coursebackend', 'serverid') === false) {
+	$res[] = tableAddConstraint('locationinfo_backendlog', 'serverid',
+		'locationinfo_coursebackend', 'serverid', 'ON UPDATE CASCADE ON DELETE CASCADE');
+}
+
 // Create response for browser
 
 if (in_array(UPDATE_RETRY, $res)) {
diff --git a/modules-available/locationinfo/lang/de/messages.json b/modules-available/locationinfo/lang/de/messages.json
index 622b94ac..bcaf687d 100644
--- a/modules-available/locationinfo/lang/de/messages.json
+++ b/modules-available/locationinfo/lang/de/messages.json
@@ -1,5 +1,4 @@
 {
-    "auth-failed": "[{{0}}] {{1}} Error: {{2}}",
     "config-saved": "Einstellungen erfolgreich gespeichert.",
     "ignored-invalid-end": "Eintrag mit ung\u00fcltiger Endzeit ignoriert",
     "ignored-invalid-range": "Eintrag mit ung\u00fcltiger Range ignoriert",
diff --git a/modules-available/locationinfo/lang/en/messages.json b/modules-available/locationinfo/lang/en/messages.json
index 348390dd..5111a408 100644
--- a/modules-available/locationinfo/lang/en/messages.json
+++ b/modules-available/locationinfo/lang/en/messages.json
@@ -1,5 +1,4 @@
 {
-    "auth-failed": "[{{0}}] {{1}} Error: {{2}}",
     "config-saved": "Config successfully saved.",
     "ignored-invalid-end": "Ignored entry with invalid end time",
     "ignored-invalid-range": "Ignored entry with invalid range",
diff --git a/modules-available/locationinfo/page.inc.php b/modules-available/locationinfo/page.inc.php
index 7be875d0..b082c0f4 100644
--- a/modules-available/locationinfo/page.inc.php
+++ b/modules-available/locationinfo/page.inc.php
@@ -59,11 +59,16 @@ class Page_LocationInfo extends Page
 	 */
 	protected function doRender()
 	{
+		$data = array('class-' . $this->show => 'active', 'errors' => []);
 		// Do this here so we always see backend errors
 		if (User::hasPermission('backend.*')) {
 			$backends = $this->loadBackends();
+			foreach ($backends as $backend) {
+				if (!empty($backend['error'])) {
+					$data['errors'][] = $backend;
+				}
+			}
 		}
-		$data = array('class-' . $this->show => 'active');
 		Permission::addGlobalTags($data['perms'], null, ['backend.*', 'location.*', 'panel.list']);
 		Render::addTemplate('page-tabs', $data);
 		switch ($this->show) {
@@ -79,6 +84,9 @@ class Page_LocationInfo extends Page
 		case 'panels':
 			$this->showPanelsTable();
 			break;
+		case 'backendlog':
+			$this->showBackendLog();
+			break;
 		default:
 			Util::redirect('?do=locationinfo');
 		}
@@ -471,7 +479,7 @@ class Page_LocationInfo extends Page
 			$serverInstance->checkConnection();
 		}
 
-		LocationInfo::setServerError($serverid, $serverInstance->getError());
+		LocationInfo::setServerError($serverid, $serverInstance->getErrors());
 	}
 
 	private function loadBackends()
@@ -495,14 +503,14 @@ class Page_LocationInfo extends Page
 			}
 
 			if (!empty($row['error'])) {
-				$row['autherror'] = true;
 				$error = json_decode($row['error'], true);
 				if (isset($error['timestamp'])) {
-					$time = date('Y/m/d H:i:s', $error['timestamp']);
+					$time = date('Y-m-d H:i', $error['timestamp']);
 				} else {
 					$time = '???';
 				}
-				Message::addError('auth-failed', $row['servername'], $time, $error['error']);
+				$row['error'] = $error['error'];
+				$row['errtime'] = $time;
 			}
 			$serverlist[] = $row;
 		}
@@ -523,6 +531,31 @@ class Page_LocationInfo extends Page
 		Render::addTemplate('page-servers', $data);
 	}
 
+	private function showBackendLog()
+	{
+		$id = Request::get('serverid', false, 'int');
+		if ($id === false) {
+			Message::addError('main.parameter-missing', 'serverid');
+			Util::redirect('?do=locationinfo');
+		}
+		$server = Database::queryFirst('SELECT servername FROM locationinfo_coursebackend
+				WHERE serverid = :id', ['id' => $id]);
+		if ($server === false) {
+			Message::addError('invalid-server-id', $id);
+			Util::redirect('?do=locationinfo');
+		}
+		$server['list'] = [];
+		$res = Database::simpleQuery('SELECT dateline, message FROM locationinfo_backendlog
+				WHERE serverid = :id ORDER BY logid DESC LIMIT 100', ['id' => $id]);
+		while ($row = $res->fetch(PDO::FETCH_ASSOC)) {
+			$row['dateline_s'] = Util::prettyTime($row['dateline']);
+			$row['class'] = substr($row['message'], 0, 3) === '[F]' ? 'text-danger' : 'text-warning';
+			$row['message'] = Substr($row['message'], 3);
+			$server['list'][] = $row;
+		}
+		Render::addTemplate('page-server-log', $server);
+	}
+
 	private function showLocationsTable()
 	{
 		$allowedLocations = User::getAllowedLocations('location.edit');
diff --git a/modules-available/locationinfo/templates/page-server-log.html b/modules-available/locationinfo/templates/page-server-log.html
new file mode 100644
index 00000000..7fc3b997
--- /dev/null
+++ b/modules-available/locationinfo/templates/page-server-log.html
@@ -0,0 +1,17 @@
+<h2>{{lang_serverLogHead}}</h2>
+<h3>{{servername}}</h3>
+
+<table class="table table-striped table-condensed">
+	<thead>
+	<th class="text-center slx-smallcol">{{lang_when}}</th>
+	<th class="text-center">{{lang_event}}</th>
+	</thead>
+	<tbody>
+	{{#list}}
+		<tr>
+			<td class="text-center" nowrap="nowrap">{{dateline_s}}</td>
+			<td class="{{class}}">{{message}}</td>
+		</tr>
+	{{/list}}
+	</tbody>
+</table>
\ No newline at end of file
diff --git a/modules-available/locationinfo/templates/page-servers.html b/modules-available/locationinfo/templates/page-servers.html
index 7c1cf79d..e295c4fd 100644
--- a/modules-available/locationinfo/templates/page-servers.html
+++ b/modules-available/locationinfo/templates/page-servers.html
@@ -9,6 +9,7 @@
 		<th>{{lang_locationName}}</th>
 		<th class="text-center slx-smallcol">{{lang_edit}}</th>
 		<th class="text-center slx-smallcol">{{lang_checkConnection}}</th>
+		<th class="text-center slx-smallcol">{{lang_showLog}}</th>
 		<th class="text-center slx-smallcol">{{lang_delete}}</th>
 	</tr>
 	</thead>
@@ -34,6 +35,11 @@
 					</button>
 				</td>
 				<td class="text-center">
+					<a href="?do=locationinfo&amp;show=backendlog&amp;serverid={{serverid}}" class="btn btn-xs btn-default">
+						<span class="glyphicon glyphicon-list-alt"></span>
+					</a>
+				</td>
+				<td class="text-center">
 					<button type="button" class="btn btn-xs btn-danger" onclick="$('#del-serverid').val({{serverid}})"
 							  data-toggle="modal" data-target="#deleteModal" {{perms.backend.edit.disabled}}>
 						<span class="glyphicon glyphicon-trash"></span>
diff --git a/modules-available/locationinfo/templates/page-tabs.html b/modules-available/locationinfo/templates/page-tabs.html
index 743297e7..14730e2f 100644
--- a/modules-available/locationinfo/templates/page-tabs.html
+++ b/modules-available/locationinfo/templates/page-tabs.html
@@ -1,3 +1,12 @@
+<div>
+	{{#errors}}
+		<div class="alert alert-danger">
+			[{{errtime}}] <a href="?do=locationinfo&amp;show=backendlog&amp;serverid={{serverid}}"><b>{{servername}}</b></a>:
+			{{error}}
+		</div>
+	{{/errors}}
+</div>
+
 <ul class="nav nav-tabs">
 	<li class="{{class-panels}} {{perms.panel.list.disabled}}"><a href="?do=locationinfo&show=panels">{{lang_panels}}</a></li>
 	<li class="{{class-locations}} {{perms.location.disabled}}"><a href="?do=locationinfo&amp;show=locations">{{lang_locationSettings}}</a></li>