From 95be8b6983ce34f50922a2c3cb6ad91d8b9c5eec Mon Sep 17 00:00:00 2001
From: rudolfkoenig <>
Date: Wed, 3 May 2017 05:30:49 +0000
Subject: [PATCH] 00_ZWDongle.pm: Reset on 0-length data (Forum #71457)

git-svn-id: https://svn.fhem.de/fhem/trunk@14174 2b470e98-0d58-463d-a4d8-8e2adae1ed80
---
 fhem/FHEM/00_ZWDongle.pm | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fhem/FHEM/00_ZWDongle.pm b/fhem/FHEM/00_ZWDongle.pm
index 259ec4df9..1aa9f6d06 100755
--- a/fhem/FHEM/00_ZWDongle.pm
+++ b/fhem/FHEM/00_ZWDongle.pm
@@ -781,9 +781,16 @@ ZWDongle_Read($@)
       last;
     }
 
+    last if(length($data) < 4);
+
     my $len = substr($data, 2, 2);
     my $l = hex($len)*2;
-    last if(!$l || length($data) < $l+4);       # Message not yet complete
+    last if(length($data) < $l+4);       # Message not yet complete
+
+    if($l < 4) {       # Bogus messages, forget the rest
+      $data = "";
+      last;
+    }
 
     $msg = substr($data, 4, $l-2);
     my $rcs  = substr($data, $l+2, 2);          # Received Checksum