feat(cbus): validate the checksum on read

apache · Jul 21, 2022 · cfffc80 · cfffc80
1 parent 905649e
commit cfffc80
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Showing 2 changed files with 24 additions and 10 deletions.
diff --git a/plc4go/protocols/cbus/readwrite/model/StaticHelper.go b/plc4go/protocols/cbus/readwrite/model/StaticHelper.go
@@ -123,16 +123,23 @@ func readBytesFromHex(logicalName string, readBuffer utils.ReadBuffer, payloadLe
 		readBuffer.Reset(readBuffer.GetPos() - 1)
 		hexBytes = hexBytes[:len(hexBytes)-1]
 	}
-	if srchk {
-		// We need to reset the last to hex bytes
-		readBuffer.Reset(readBuffer.GetPos() - 2)
-		hexBytes = hexBytes[:len(hexBytes)-2]
-	}
 	rawBytes := make([]byte, hex.DecodedLen(len(hexBytes)))
 	n, err := hex.Decode(rawBytes, hexBytes)
 	if err != nil {
 		return nil, err
 	}
+	if srchk {
+		checksum := byte(0x0)
+		for _, aByte := range rawBytes {
+			checksum += aByte
+		}
+		if checksum != 0x0 {
+			return nil, errors.New("Checksum validation failed")
+		}
+		// We need to reset the last to hex bytes
+		readBuffer.Reset(readBuffer.GetPos() - 2)
+		rawBytes = rawBytes[:len(rawBytes)-1]
+	}
 	log.Debug().Msgf("%d bytes decoded", n)
 	return rawBytes, nil
 }

diff --git a/.../drivers/c-bus/src/main/java/org/apache/plc4x/java/cbus/readwrite/utils/StaticHelper.java b/.../drivers/c-bus/src/main/java/org/apache/plc4x/java/cbus/readwrite/utils/StaticHelper.java
@@ -102,17 +102,24 @@ private static byte[] readBytesFromHex(String logicalName, ReadBuffer readBuffer
             readBuffer.reset(readBuffer.getPos() - 1);
             hexBytes = Arrays.copyOf(hexBytes, hexBytes.length - 1);
         }
-        if (srchk) {
-            // We need to reset the last to hex bytes
-            readBuffer.reset(readBuffer.getPos() - 2);
-            hexBytes = Arrays.copyOf(hexBytes, hexBytes.length - 2);
-        }
         byte[] rawBytes;
         try {
             rawBytes = Hex.decodeHex(new String(hexBytes));
         } catch (DecoderException e) {
             throw new ParseException("error getting hex", e);
         }
+        if (srchk) {
+            byte checksum = 0x0;
+            for (byte aByte : rawBytes) {
+                checksum+=aByte;
+            }
+            if (checksum != 0x0) {
+                throw new ParseException("Checksum validation failed");
+            }
+            // We need to reset the last to hex bytes
+            readBuffer.reset(readBuffer.getPos() - 2);
+            rawBytes = Arrays.copyOf(rawBytes, rawBytes.length - 1);
+        }
         return rawBytes;
     }