-extern Uint16 IPv4_Checksum(void *Buf, int Size);
-extern int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, void *Data);
+extern Uint16 IPv4_Checksum(const void *Buf, size_t Length);
+extern int IPv4_SendPacket(tInterface *Iface, tIPv4 Address, int Protocol, int ID, int Length, const void *Data);