Add more validation to serial read state machine

avr/send.c

@@ -198,8 +198,24 @@ int main() {
             }
 
             case 2: {
-                header.type = c;
+                switch (c) {
-                i++;
+                    case 0x01:
+                    case 0x02:
+                    case 0x04:
+                    case 0x08:
+                    case 0x0f: {
+                        header.type = c;
+                        i++;
+
+                        break;
+                    }
+
+                    default: {
+                        i = 0;
+
+                        break;
+                    }
+                }
 
                 break;
             }