2.11BSD/sys/netinet/ip.h

/*
 * Copyright (c) 1982, 1986 Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that this notice is preserved and that due credit is given
 * to the University of California at Berkeley. The name of the University
 * may not be used to endorse or promote products derived from this
 * software without specific prior written permission. This software
 * is provided ``as is'' without express or implied warranty.
 *
 *	@(#)ip.h	7.6.1.2 (2.11BSD) 1995/10/09
 */
#ifndef BYTE_ORDER
/*
 * Definitions for byte order,
 * according to byte significance from low address to high.
 */
#define	LITTLE_ENDIAN	1234	/* least-significant byte first (vax) */
#define	BIG_ENDIAN	4321	/* most-significant byte first (IBM, net) */
#define	PDP_ENDIAN	3412	/* LSB first in word, MSW first in long (pdp) */

#ifdef vax
#define	BYTE_ORDER	LITTLE_ENDIAN
#else
#ifdef pdp11
#define	BYTE_ORDER	PDP_ENDIAN
#else
#define	BYTE_ORDER	BIG_ENDIAN	/* mc68000, tahoe, most others */
#endif
#endif
#endif BYTE_ORDER

/*
 * Definitions for internet protocol version 4.
 * Per RFC 791, September 1981.
 */
#define	IPVERSION	4

/*
 * Structure of an internet header, naked of options.
 *
 * We declare ip_len and ip_off to be short, rather than u_short
 * pragmatically since otherwise unsigned comparisons can result
 * against negative integers quite easily, and fail in subtle ways.
 */
struct ip {
#if BYTE_ORDER == LITTLE_ENDIAN
	u_char	ip_hl:4,		/* header length */
		ip_v:4;			/* version */
#endif
#if BYTE_ORDER == BIG_ENDIAN
	u_char	ip_v:4,			/* version */
		ip_hl:4;		/* header length */
#endif
#if BYTE_ORDER == PDP_ENDIAN
	u_int	ip_hl:4,		/* header length */
		ip_v:4;			/* version */
#endif
	u_char	ip_tos;			/* type of service */
	short	ip_len;			/* total length */
	u_short	ip_id;			/* identification */
	short	ip_off;			/* fragment offset field */
#define	IP_DF 0x4000			/* dont fragment flag */
#define	IP_MF 0x2000			/* more fragments flag */
	u_char	ip_ttl;			/* time to live */
	u_char	ip_p;			/* protocol */
	u_short	ip_sum;			/* checksum */
	struct	in_addr ip_src,ip_dst;	/* source and dest address */
};

#define	IP_MAXPACKET	65535L		/* maximum packet size */

/*
 * Definitions for options.
 */
#define	IPOPT_COPIED(o)		((o)&0x80)
#define	IPOPT_CLASS(o)		((o)&0x60)
#define	IPOPT_NUMBER(o)		((o)&0x1f)

#define	IPOPT_CONTROL		0x00
#define	IPOPT_RESERVED1		0x20
#define	IPOPT_DEBMEAS		0x40
#define	IPOPT_RESERVED2		0x60

#define	IPOPT_EOL		0		/* end of option list */
#define	IPOPT_NOP		1		/* no operation */

#define	IPOPT_RR		7		/* record packet route */
#define	IPOPT_TS		68		/* timestamp */
#define	IPOPT_SECURITY		130		/* provide s,c,h,tcc */
#define	IPOPT_LSRR		131		/* loose source route */
#define	IPOPT_SATID		136		/* satnet id */
#define	IPOPT_SSRR		137		/* strict source route */

/*
 * Offsets to fields in options other than EOL and NOP.
 */
#define	IPOPT_OPTVAL		0		/* option ID */
#define	IPOPT_OLEN		1		/* option length */
#define IPOPT_OFFSET		2		/* offset within option */
#define	IPOPT_MINOFF		4		/* min value of above */

/*
 * Time stamp option structure.
 */
struct	ip_timestamp {
	u_char	ipt_code;		/* IPOPT_TS */
	u_char	ipt_len;		/* size of structure (variable) */
	u_char	ipt_ptr;		/* index of current entry */
#if BYTE_ORDER == LITTLE_ENDIAN
	u_char	ipt_flg:4,		/* flags, see below */
		ipt_oflw:4;		/* overflow counter */
#endif
#if BYTE_ORDER == BIG_ENDIAN
	u_char	ipt_oflw:4,		/* overflow counter */
		ipt_flg:4;		/* flags, see below */
#endif
#if BYTE_ORDER == PDP_ENDIAN
	u_char	ipt_flg:4,		/* flags, see below */
		ipt_oflw:4;		/* overflow counter */
#endif
	union ipt_timestamp {
		n_long	ipt_time[1];
		struct	ipt_ta {
			struct in_addr ipt_addr;
			n_long ipt_time;
		} ipt_ta[1];
	} ipt_timestamp;
};

/* flag bits for ipt_flg */
#define	IPOPT_TS_TSONLY		0		/* timestamps only */
#define	IPOPT_TS_TSANDADDR	1		/* timestamps and addresses */
#define	IPOPT_TS_PRESPEC	2		/* specified modules only */

/* bits for security (not byte swapped) */
#define	IPOPT_SECUR_UNCLASS	0x0000
#define	IPOPT_SECUR_CONFID	0xf135
#define	IPOPT_SECUR_EFTO	0x789a
#define	IPOPT_SECUR_MMMM	0xbc4d
#define	IPOPT_SECUR_RESTR	0xaf13
#define	IPOPT_SECUR_SECRET	0xd788
#define	IPOPT_SECUR_TOPSECRET	0x6bc5

/*
 * Internet implementation parameters.
 */
#define	MAXTTL		255		/* maximum time to live (seconds) */
#define	IPDEFTTL	64		/* default ttl, from RFC 1340 */
#define	IPFRAGTTL	60		/* time to live for frags, slowhz */
#define	IPTTLDEC	1		/* subtracted when forwarding */

#define	IP_MSS		576		/* default maximum segment size */