Handle a NWL 0x81 ci-field, but does not understand it... yet.

simulations/simulation_broken.txt

@@ -0,0 +1,3 @@
+# This telegram is not really broken, but the current dvparser fails, in particular the end triggers a varlen with
+# not enough bytes in the telegram. When the protocol/dvparser is improved, a replacement telegram should be placed here.
+telegram=|3444EE4D813929271608|811D|7A51000000|046D1912A62B036E000000|5170426CE1F1436E00000002FF2C00000259D6D0D4090265FC0902FD66A00044C4|

src/dvparser.cc

@@ -253,11 +253,7 @@ bool parseDV(Telegram *t,
         int remaining = std::distance(data, data_end);
         if (variable_length) {
             DEBUG_PARSER("(dvparser debug) varlen %02x\n", *(data+0));
-            if (remaining > 2) {
-                datalen = *(data);
-            } else {
-                datalen = remaining;
-            }
+            datalen = *(data);
         }
         DEBUG_PARSER("(dvparser debug) remaining data %d len=%d\n", remaining, datalen);
         if (remaining < datalen) {
@@ -267,7 +263,7 @@ bool parseDV(Telegram *t,
 
         // Skip the length byte in the variable length data.
         if (variable_length) {
-            t->addExplanationAndIncrementPos(data, 1, "%02X varlen=%d", datalen, datalen);
+            t->addExplanationAndIncrementPos(data, 1, "%02X varlen=%d", *(data+0), datalen);
         }
         string value = bin2hex(data, data_end, datalen);
         int offset = start_parse_here+data-data_start;

src/wmbus.cc

@@ -595,6 +595,7 @@ string mediaTypeJSON(int a_field_device_type, int m_field)
     X(0x78, TPL_78,  "TPL: no header APL follows", 0, CI_TYPE::TPL, "") \
     X(0x79, TPL_79,  "TPL: compact APL follows", 0, CI_TYPE::TPL, "") \
     X(0x7A, TPL_7A,  "TPL: short header APL follows", 0, CI_TYPE::TPL, "") \
+    X(0x81, NWL_81,  "NWL: TPL or APL follows?", 0, CI_TYPE::NWL, "") \
     X(0x8C, ELL_I,   "ELL: I",    2, CI_TYPE::ELL, "CC, ACC") \
     X(0x8D, ELL_II,  "ELL: II",   8, CI_TYPE::ELL, "CC, ACC, SN, Payload CRC") \
     X(0x8E, ELL_III, "ELL: III", 10, CI_TYPE::ELL, "CC, ACC, M2, A2") \
@@ -1030,6 +1031,23 @@ bool Telegram::parseELL(vector<uchar>::iterator &pos)
 
 bool Telegram::parseNWL(vector<uchar>::iterator &pos)
 {
+    int remaining = distance(pos, frame.end());
+    if (remaining == 0) return false;
+
+    debug("(wmbus) parseNWL @%d %d\n", distance(frame.begin(), pos), remaining);
+    int ci_field = *pos;
+    if (!isCiFieldOfType(ci_field, CI_TYPE::NWL)) return true;
+    addExplanationAndIncrementPos(pos, 1, "%02x nwl-ci-field (%s)",
+                                  ci_field, ciType(ci_field).c_str());
+    nwl_ci = ci_field;
+    // We have only seen 0x81 0x1d so far.
+    int len = 1; // ciFieldLength(nwl_ci);
+
+    if (remaining < len+1) return expectedMore(__LINE__);
+
+    uchar nwl = *pos;
+    addExplanationAndIncrementPos(pos, 1, "%02x nwl?", nwl);
+
     return true;
 }
 

test.sh

@@ -114,6 +114,9 @@ if [ "$?" != "0" ]; then RC="1"; fi
 ./tests/test_hex_cmdline.sh $PROG
 if [ "$?" != "0" ]; then RC="1"; fi
 
+./tests/test_broken.sh $PROG
+if [ "$?" != "0" ]; then RC="1"; fi
+
 if [ -x ../additional_tests.sh ]
 then
     (cd ..; ./additional_tests.sh $PROG)

tests/test_broken.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+
+PROG="$1"
+TEST=testoutput
+mkdir -p $TEST
+
+TESTNAME="Test broken telegrams"
+TESTRESULT="ERROR"
+
+cat > $TEST/test_expected.txt <<EOF
+(dvparser) warning: unexpected end of data
+(dvparser) found new format "046D036E51706CE1F14302FF2C0259D40902FD66A000" with hash 48a9, remembering!
+(dvparser) warning: unexpected end of data
+(dvparser) warning: unexpected end of data
+EOF
+
+$PROG --format=fields --selectfields=id,current_consumption_hca,device_date_time --debug simulations/simulation_broken.txt HCA auto 27293981 NOKEY 2>&1 | grep dvparser > $TEST/test_output.txt
+
+if [ "$?" = "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