Add interface struct for communication between protocols and protocols stack.

Changed the protocols structs to use one struct for each layer.

include/grub/net/udp.h

@@ -1,22 +1,23 @@
 #ifndef GRUB_NET_UDP_HEADER
 #define GRUB_NET_UDP_HEADER	1
 #include <grub/misc.h>
-/*
-typedef enum
-  {
-    GRUB_PROT_TFTP
-  } protocol_type;
-*/
 
-#define GRUB_PROT_TFTP 1 
-
-struct udphdr {
+struct udphdr
+{
   grub_uint16_t src;
   grub_uint16_t dst;
   grub_uint16_t len;
   grub_uint16_t chksum;
 } __attribute__ ((packed));
 
+struct udp_interf
+{
+  grub_uint16_t src;
+  grub_uint16_t dst;
+};
+
+
+
 void udp_ini(void);
 void udp_fini(void);
 #endif