String \0 terminated in group objects

OpenKNX · Jun 19, 2024 · c5defe9 · c5defe9
1 parent acf4a0b
commit c5defe9
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Showing 4 changed files with 24 additions and 11 deletions.
diff --git a/src/knx/dptconvert.cpp b/src/knx/dptconvert.cpp
@@ -517,15 +517,13 @@ int busValueToAccess(const uint8_t* payload, size_t payload_length, const Dpt& d
 int busValueToString(const uint8_t* payload, size_t payload_length, const Dpt& datatype, KNXValue& value)
 {
     ASSERT_PAYLOAD(14);
-    char strValue[15];
-    strValue[14] = '\0';
     for (int n = 0; n < 14; ++n)
     {
-        strValue[n] = signed8FromPayload(payload, n);
-        if (!datatype.subGroup && (strValue[n] & 0x80))
+        auto value = signed8FromPayload(payload, n);
+        if (!datatype.subGroup && (value & 0x80))
             return false;
     }
-    value = strValue;
+    value = (const char*) payload;
     return true;
 }
 

diff --git a/src/knx/group_object.cpp b/src/knx/group_object.cpp
@@ -22,7 +22,7 @@ GroupObject::GroupObject()
 
 GroupObject::GroupObject(const GroupObject& other)
 {
-    _data = new uint8_t[other._dataLength];
+    _data = new uint8_t[other._table != nullptr ? other.sizeInMemory() : other._dataLength];
     _commFlagEx = other._commFlagEx;
     _dataLength = other._dataLength;
     _asap = other._asap;
@@ -114,12 +114,12 @@ size_t GroupObject::goSize()
     size_t size = sizeInTelegram();
     if (size == 0)
         return 1;
-
+ 
     return size;
 }
 
 // see knxspec 3.5.1 p. 178
-size_t GroupObject::asapValueSize(uint8_t code)
+size_t GroupObject::asapValueSize(uint8_t code) const
 {
     if (code < 7)
         return 0;
@@ -194,6 +194,16 @@ size_t GroupObject::sizeInTelegram()
     return asapValueSize(code);
 }
 
+size_t GroupObject::sizeInMemory() const
+{
+    uint8_t code = lowByte(ntohs(_table->_tableData[_asap]));
+    size_t result = asapValueSize(code);
+    if (code == 0)
+        return 1;
+    if (code == 14)
+        return 14 + 1;
+}
+
 #ifdef SMALL_GROUPOBJECT
 GroupObjectUpdatedHandler GroupObject::classCallback()
 {

diff --git a/src/knx/group_object.h b/src/knx/group_object.h
@@ -139,6 +139,11 @@ class GroupObject
      * will return 0.
      */
     size_t sizeInTelegram();
+    /**
+     * returns the size of the group object in the heap memory of the group object. The function returns the same value as goSize(), 
+     * exept fot the 14 byte string type to reserve one byte of a \0 terminator character.
+     */
+    size_t sizeInMemory() const;
     /**
      * returns the pointer to the value of the group object. This can be used if a datapoint type is not supported or if you want do 
      * your own conversion.
@@ -274,7 +279,7 @@ class GroupObject
     static GroupObjectUpdatedHandler _updateHandlerStatic;
 #endif
 
-    size_t asapValueSize(uint8_t code);
+    size_t asapValueSize(uint8_t code) const;
     size_t goSize();
     uint16_t _asap = 0;
     ComFlagEx _commFlagEx;

diff --git a/src/knx/group_object_table_object.cpp b/src/knx/group_object_table_object.cpp
@@ -107,9 +107,9 @@ bool GroupObjectTableObject::initGroupObjects()
         GroupObject& go = _groupObjects[asap - 1];
         go._asap = asap;
         go._table = this;
-        
+
         go._dataLength = go.goSize();
-        go._data = new uint8_t[go._dataLength];
+        go._data = new uint8_t[go.sizeInMemory()];
         memset(go._data, 0, go._dataLength);
 
         if (go.valueReadOnInit())