Added global pointer

src/goodbyedpi.c

@@ -577,6 +577,7 @@ static void send_native_fragment(HANDLE w_filter, WINDIVERT_ADDRESS addr,
 }
 
 int main(int argc, char *argv[]) {
+    debugPrint = &printf;
     static enum packet_type_e {
         unknown,
         ipv4_tcp, ipv4_tcp_data, ipv4_udp_data,

src/goodbyedpi.h

@@ -1,8 +1,11 @@
 #define HOST_MAXLEN 253
 #define MAX_PACKET_SIZE 9016
-
+extern int (*debugPrint)(char const *const _Format, ...);
 #ifndef DEBUG
-#define debug(...) do {} while (0)
+#define debug(...)                                                             \
+	if (debugPrint) {                                                            \
+		debugPrint(__VA_ARGS__);                                                   \
+	}
 #else
 #define debug(...) printf(__VA_ARGS__)
 #endif