ethernet.h revision 22975 
1/*
2 * Fundamental constants relating to ethernet.
3 *
4 * $Id$
5 *
6 */
7
8#ifndef _NET_ETHERNET_H_
9#define _NET_ETHERNET_H_
10
11/*
12 * The number of bytes in an ethernet (MAC) address.
13 */
14#define	ETHER_ADDR_LEN		6
15
16/*
17 * The number of bytes in the type field.
18 */
19#define	ETHER_TYPE_LEN		2
20
21/*
22 * The number of bytes in the trailing CRC field.
23 */
24#define	ETHER_CRC_LEN		4
25
26/*
27 * The length of the combined header.
28 */
29#define	ETHER_HDR_LEN		(ETHER_ADDR_LEN*2+ETHER_TYPE_LEN)
30
31/*
32 * The minimum packet length.
33 */
34#define	ETHER_MIN_LEN		64
35
36/*
37 * The maximum packet length.
38 */
39#define	ETHER_MAX_LEN		1518
40
41/*
42 * A macro to validate a length with
43 */
44#define	ETHER_IS_VALID_LEN(foo)	\
45	((foo) >= ETHER_MIN_LEN && (foo) <= ETHER_MAX_LEN)
46
47/*
48 * Structure of a 10Mb/s Ethernet header.
49 */
50struct	ether_header {
51	u_char	ether_dhost[ETHER_ADDR_LEN];
52	u_char	ether_shost[ETHER_ADDR_LEN];
53	u_short	ether_type;
54};
55
56/*
57 * Structure of a 48-bit Ethernet address.
58 */
59struct	ether_addr {
60	u_char octet[ETHER_ADDR_LEN];
61};
62
63#define	ETHERTYPE_PUP		0x0200	/* PUP protocol */
64#define	ETHERTYPE_IP		0x0800	/* IP protocol */
65#define ETHERTYPE_ARP		0x0806	/* Addr. resolution protocol */
66#define ETHERTYPE_REVARP	0x8035	/* reverse Addr. resolution protocol */
67#define	ETHERTYPE_LOOPBACK	0x9000	/* used to test interfaces */
68/* XXX - add more useful types here */
69
70/*
71 * The ETHERTYPE_NTRAILER packet types starting at ETHERTYPE_TRAIL have
72 * (type-ETHERTYPE_TRAIL)*512 bytes of data followed
73 * by an ETHER type (as given above) and then the (variable-length) header.
74 */
75#define	ETHERTYPE_TRAIL		0x1000		/* Trailer packet */
76#define	ETHERTYPE_NTRAILER	16
77
78#define	ETHERMTU	(ETHER_MAX_LEN-ETHER_HDR_LEN-ETHER_CRC_LEN)
79#define	ETHERMIN	(ETHER_MIN_LEN-ETHER_HDR_LEN-ETHER_CRC_LEN)
80
81#ifndef KERNEL
82#include <sys/cdefs.h>
83
84/*
85 * Ethernet address conversion/parsing routines.
86 */
87__BEGIN_DECLS
88struct	ether_addr *ether_aton __P((char *));
89int	ether_hostton __P((char *, struct ether_addr *));
90int	ether_line __P((char *, struct ether_addr *, char *));
91char 	*ether_ntoa __P((struct ether_addr *));
92int	ether_ntohost __P((char *, struct ether_addr *));
93__END_DECLS
94#endif /* !KERNEL */
95
96#endif /* !_NET_ETHERNET_H_ */
97