From 205b5593a8e6865b8b0ffe81b1e8feebe85340eb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fredrik=20=C3=96hrstr=C3=B6m?= <oehrstroem@gmail.com>
Date: Fri, 12 May 2023 21:05:36 +0200
Subject: [PATCH] Print warning if decode of zero length telegram is attempted.

---
 src/wmbus.cc        | 2 ++
 src/wmbus_rawtty.cc | 8 ++++++++
 2 files changed, 10 insertions(+)

diff --git a/src/wmbus.cc b/src/wmbus.cc
index 54e2dad..8057e65 100644
--- a/src/wmbus.cc
+++ b/src/wmbus.cc
@@ -4126,6 +4126,8 @@ bool BusDeviceCommonImplementation::handleTelegram(AboutTelegram &about, vector<
     bool handled = false;
     last_received_ = time(NULL);
 
+    assert(frame.size() > 0);
+
     if (about.type == FrameType::MBUS && frame.size() == 1)
     {
         if (frame[0] == 0xe5)
diff --git a/src/wmbus_rawtty.cc b/src/wmbus_rawtty.cc
index 8bcd559..a8535a6 100644
--- a/src/wmbus_rawtty.cc
+++ b/src/wmbus_rawtty.cc
@@ -211,6 +211,14 @@ void WMBusRawTTY::processSerialData()
     {
         FrameStatus status = checkWMBusFrame(data_buffer_, &frame_length, &payload_len, &payload_offset, false);
 
+        if (payload_len == 0)
+        {
+            verbose("(rawtty) protocol error in message received length byte is zero!\n");
+            string msg = bin2hex(data_buffer_);
+            debug("(rawtty) protocol error \"%s\"\n", msg.c_str());
+            data_buffer_.clear();
+            break;
+        }
         if (status == PartialFrame)
         {
             // Partial frame, stop eating.