refactor(npdu): fail early on protocol version mismatch

BiancoRoyal · May 15, 2024 · c120144 · c120144
1 parent 5e22199
commit c120144
Showing 1 changed file with 4 additions and 4 deletions.
diff --git a/lib/npdu.js b/lib/npdu.js
@@ -52,7 +52,10 @@ module.exports.decodeFunction = (buffer, offset) => {
 module.exports.decode = (buffer, offset) => {
   let adrLen;
   const orgOffset = offset;
-  offset++;
+  const protocolVersion = buffer[offset++];
+  if (protocolVersion !== BACNET_PROTOCOL_VERSION) {
+    return undefined;
+  }
   const funct = buffer[offset++];
   let destination;
   if (funct & baEnum.NpduControlBit.DESTINATION_SPECIFIED) {
@@ -80,9 +83,6 @@ module.exports.decode = (buffer, offset) => {
       offset += 2;
     }
   }
-  if (buffer[orgOffset + 0] !== BACNET_PROTOCOL_VERSION) {
-    return undefined;
-  }
   return {
     len: offset - orgOffset,
     funct,