4.1cBSD/a/sys/netinet/ip.h

/* ip.h 1.11 82/12/28 */

/*
 * 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 {
#ifdef vax
	u_char	ip_hl:4,		/* header length */
		ip_v:4;			/* version */
#endif
#ifdef sun
	u_char	ip_v:4,			/* version */
		ip_hl:4;		/* header length */
#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 */
};

/*
 * Definitions for options.
 */
#define	IPOPT_COPIED(o)		((o)&0x80)
#define	IPOPT_CLASS(o)		((o)&0x40)
#define	IPOPT_NUMBER(o)		((o)&0x3f)

#define	IPOPT_CONTROL		0x00
#define	IPOPT_RESERVED1		0x10
#define	IPOPT_DEBMEAS		0x20
#define	IPOPT_RESERVED2		0x30

#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 */

/*
 * 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 */
	u_char	ipt_flg:4,		/* flags, see below */
		ipt_oflw:4;		/* overflow counter */
	union {
		n_long	ipt_time[1];
		struct	ipt_ta {
			struct in_addr ipt_addr;
			n_long ipt_time;
		} ipt_ta[1];
	}
};

/* 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	IPFRAGTTL	15		/* time to live for frag chains */
#define	IPTTLDEC	5		/* subtracted when forwarding */