Fix KISS beacon frame length

Fix frame length handling to meet minimum length requirements (15 bytes) for
TNCs like Direwolf. Previously, raw beacon data was being sent directly,
causing frame length errors.

Changed code to pad beacon data with zeros to ensure minimum frame length.

RNS/Interfaces/KISSInterface.py

@@ -319,7 +319,13 @@ def readLoop(self):
                             if time.time() > self.first_tx + self.beacon_i:
                                 RNS.log("Interface "+str(self)+" is transmitting beacon data: "+str(self.beacon_d.decode("utf-8")), RNS.LOG_DEBUG)
                                 self.first_tx = None
-                                self.processOutgoing(self.beacon_d)
+
+                                # Pad to minimum length
+                                frame = bytearray(self.beacon_d)
+                                while len(frame) < 15:
+                                    frame.append(0x00)
+
+                                self.processOutgoing(bytes(frame))
 
         except Exception as e:
             self.online = False