add arpa/tftp.h

include/arpa/tftp.h

+#ifndef _ARPA_TFTP_H
+#define _ARPA_TFTP_H
+#define SEGSIZE 512
+#define RRQ 01
+#define WRQ 02
+#define DATA 03
+#define ACK 04
+#define ERROR 05
+struct tftphdr {
+	short th_opcode;
+	union {
+		unsigned short tu_block;
+		short tu_code;
+		char tu_stuff[1];
+	} th_u;
+	char th_data[1];
+};
+#define th_block th_u.tu_block
+#define th_code th_u.tu_code
+#define th_stuff th_u.tu_stuff
+#define th_msg th_data
+#define EUNDEF 0
+#define ENOTFOUND 1
+#define EACCESS 2
+#define ENOSPACE 3
+#define EBADOP 4
+#define EBADID 5
+#define EEXISTS 6
+#define ENOUSER 7
+#endif
+