Fix bug where valid rtlwmbus telegrams were ignored when they came after a crc broken telegram. This bug did not tigger for the normal rtlsdr rtlwmbus usage. It triggered when piping an archive file with collected telegrams into wmbusmeters.

simulations/simulation_rtlwmbus_errors.txt

@@ -0,0 +1,4 @@
+T1;0;0;2021-12-29 13:50:57.000;8;101;91625359;0x294468505953629176f0a0009f29982b00e0982b00802e0601316acd636bcd63008dc3009ed4000fe5ff
+T1;0;0;2021-12-29 13:50:57.000;11;108;91625359;0x294468505953629176f0a0009f29982b00e0982b00802e0601316acd636bcd63008dc3009ed4000fe5ff
+C1;1;1;2021-12-29 13:50:57.000;94;83;03727567;0x574468506775720394088c0048900f002c25b3290900aa7c765a7dfed6737ab300300710bcabff50afff489e689f834a0bd9578ad52fb85f17854d3d5d522cbec020526a6242e2345a48214088a6a9b8ebfd47f80f15a3b4
+C1;1;1;2021-12-29 13:50:57.000;96;87;03727567;0x574468506775720394088c0048900f002c25b3290900aa7c765a7dfed6737ab300300710bcabff50afff489e689f834a0bd9578ad52fb85f17854d3d5d522cbec020526a6242e2345a48214088a6a9b8ebfd47f80f15a3b4

src/wmbus_rtlwmbus.cc

@@ -1,5 +1,5 @@
 /*
- Copyright (C) 2019-2020 Fredrik Öhrström
+ Copyright (C) 2019-2021 Fredrik Öhrström
 
  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
@@ -248,19 +248,17 @@ void WMBusRTLWMBUS::processSerialData()
         {
             break;
         }
-        if (status == TextAndNotFrame)
+        else if (status == TextAndNotFrame)
         {
             // The buffer has already been printed by serial cmd.
-            read_buffer_.clear();
-            break;
+            read_buffer_.erase(read_buffer_.begin(), read_buffer_.begin()+frame_length);
         }
-        if (status == ErrorInFrame)
+        else if (status == ErrorInFrame)
         {
             debug("(rtlwmbus) error in received message.\n");
-            read_buffer_.clear();
-            break;
+            read_buffer_.erase(read_buffer_.begin(), read_buffer_.begin()+frame_length);
         }
-        if (status == FullFrame)
+        else if (status == FullFrame)
         {
             vector<uchar> payload;
             if (hex_payload_len > 0)
@@ -302,6 +300,10 @@ void WMBusRTLWMBUS::processSerialData()
             AboutTelegram about(id, rssi, FrameType::WMBUS);
             handleTelegram(about, payload);
         }
+        else
+        {
+            assert(0);
+        }
     }
 }
 
@@ -333,11 +335,13 @@ FrameStatus WMBusRTLWMBUS::checkRTLWMBUSFrame(vector<uchar> &data,
         return PartialFrame;
     }
 
+    // Export how long the current line is, so that it can be removed from the buffer.
+    *hex_frame_length = eolp+1;
+
     // We got a full line, but if it is too short, then
     // there is something wrong. Discard the data.
     if (data.size() < 10)
     {
-
         debug("(rtlwmbus) too short line\n");
         return ErrorInFrame;
     }
@@ -411,7 +415,6 @@ FrameStatus WMBusRTLWMBUS::checkRTLWMBUSFrame(vector<uchar> &data,
     payload_len = eolp-i;
     *hex_payload_len_out = payload_len;
     *hex_payload_offset = i;
-    *hex_frame_length = eolp+1;
 
     debug("(rtlwmbus) received full frame\n");
     return FullFrame;

test.sh

@@ -120,6 +120,9 @@ if [ "$?" != "0" ]; then RC="1"; fi
 ./tests/test_broken.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 
+./tests/test_rtlwmbus_crc_errors.sh $PROG
+if [ "$?" != "0" ]; then RC="1"; fi
+
 ./tests/test_analyze.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 

tests/test_rtlwmbus_crc_errors.sh

@@ -0,0 +1,35 @@
+#!/bin/sh
+
+PROG="$1"
+TEST=testoutput
+mkdir -p $TEST
+
+TESTNAME="Test rtlwmbus with crc errors"
+TESTRESULT="ERROR"
+
+cat > $TEST/test_expected.txt <<EOF
+Started config rtlwmbus on stdin listening on any
+No meters configured. Printing id:s of all telegrams heard!
+Received telegram from: 03727567
+          manufacturer: (TCH) Techem Service (0x5068)
+                  type: Heat Cost Allocator (0x08) encrypted
+                   ver: 0x94
+                device: rtlwmbus[]
+                  rssi: 94 dBm
+                driver: fhkvdataiv
+EOF
+
+cat simulations/simulation_rtlwmbus_errors.txt | $PROG stdin:rtlwmbus > $TEST/test_output.txt 2>&1
+
+if [ "$?" = "0" ]
+then
+    diff $TEST/test_expected.txt $TEST/test_output.txt
+    if [ "$?" = "0" ]
+    then
+        echo OK: $TESTNAME
+        TESTRESULT="OK"
+    fi
+else
+    echo "wmbusmeters returned error code: $?"
+    cat $TEST/test_output.txt
+fi