Add security logger to RedDAV.

Some smaller clean ups whitepsaces and tabs, use PHP_EOL, Doxygen, etc.

include/auth.php

@@ -41,6 +41,9 @@ function nuke_session() {
 /**
  * @brief Verify login credentials.
  *
+ * If system <i>authlog</i> is set a log entry will be added for failed login
+ * attempts.
+ *
  * @param string $email
  *  The email address to verify.
  * @param string $pass
@@ -88,14 +91,25 @@ function account_verify_password($email, $pass) {
 	if($record['account_flags'] & ACCOUNT_PENDING)
 		logger('Account is pending. account_flags = ' . $record['account_flags']);
 
-	// Also log failed logins to a separate auth log to reduce overhead for server side intrusion prevention
-	$authlog = get_config('system', 'authlog');
-	if ($authlog)
-		@file_put_contents($authlog, datetime_convert() . ':' . session_id() . ' ' . $error . "\n", FILE_APPEND);
+	log_failed_login($error);
 
 	return null;
 }
 
+/**
+ * @brief Log failed logins to a separate auth log.
+ *
+ * Can be used to reduce overhead for server side intrusion prevention, like
+ * parse the authlog file with something like fail2ban, OSSEC, etc.
+ *
+ * @param string $errormsg
+ *  Error message to display for failed login.
+ */
+function log_failed_login($errormsg) {
+	$authlog = get_config('system', 'authlog');
+	if ($authlog)
+		@file_put_contents($authlog, datetime_convert() . ':' . session_id() . ' ' . $errormsg . PHP_EOL, FILE_APPEND);
+}
 
 /**
  * Inline - not a function