Add more validation to serial read state machine

avr/send.c

@@ -198,12 +198,28 @@ int main() {
             }
 
             case 2: {
+                switch (c) {
+                    case 0x01:
+                    case 0x02:
+                    case 0x04:
+                    case 0x08:
+                    case 0x0f: {
                         header.type = c;
                         i++;
 
                         break;
                     }
 
+                    default: {
+                        i = 0;
+
+                        break;
+                    }
+                }
+
+                break;
+            }
+
             case 3: {
                 header.compression = c;
                 i++;