This is xnu-8019. See this file in:
/*
 * Copyright (c) 2000-2016 Apple Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 *
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 *
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 *
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1982, 1986, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)ip.h	8.2 (Berkeley) 6/1/94
 * $FreeBSD: src/sys/netinet/ip.h,v 1.17 1999/12/22 19:13:20 shin Exp $
 */

#ifndef _NETINET_IP_H_
#define _NETINET_IP_H_
#ifndef DRIVERKIT
#include <sys/appleapiopts.h>
#include <sys/types.h>          /* XXX temporary hack to get u_ types */
#else
#include <sys/_types.h>
#include <sys/_types/_u_int.h>
#include <sys/_types/_u_char.h>
#include <sys/_types/_u_short.h>

#include <machine/endian.h>
#endif /* DRIVERKIT */

#include <netinet/in.h>
#include <netinet/in_systm.h>

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

/*
 * Structure of an internet header, naked of options.
 */
struct ip {
#ifdef _IP_VHL
	u_char  ip_vhl;                 /* version << 4 | header length >> 2 */
#else
#if BYTE_ORDER == LITTLE_ENDIAN
	u_int   ip_hl:4,                /* header length */
	    ip_v:4;                     /* version */
#endif
#if BYTE_ORDER == BIG_ENDIAN
	u_int   ip_v:4,                 /* version */
	    ip_hl:4;                    /* header length */
#endif
#endif /* not _IP_VHL */
	u_char  ip_tos;                 /* type of service */
	u_short ip_len;                 /* total length */
	u_short ip_id;                  /* identification */
	u_short ip_off;                 /* fragment offset field */
#define IP_RF 0x8000                    /* reserved fragment flag */
#define IP_DF 0x4000                    /* dont fragment flag */
#define IP_MF 0x2000                    /* more fragments flag */
#define IP_OFFMASK 0x1fff               /* mask for fragmenting bits */
	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 */
};

#ifdef _IP_VHL
#define IP_MAKE_VHL(v, hl)      ((uint8_t)((v) << 4 | (hl)))
#define IP_VHL_HL(vhl)          ((vhl) & 0x0f)
#define IP_VHL_V(vhl)           ((vhl) >> 4)
#define IP_VHL_BORING           0x45
#endif

#define IP_MAXPACKET    65535           /* maximum packet size */

/*
 * Definitions for IP type of service (ip_tos)
 */
#define IPTOS_LOWDELAY          0x10
#define IPTOS_THROUGHPUT        0x08
#define IPTOS_RELIABILITY       0x04
#define IPTOS_MINCOST           0x02
#if 1
/* ECN RFC3168 obsoletes RFC2481, and these will be deprecated soon. */
#define IPTOS_CE                0x01
#define IPTOS_ECT               0x02
#endif

#define IPTOS_DSCP_SHIFT        2

/*
 * ECN (Explicit Congestion Notification) codepoints in RFC3168
 * mapped to the lower 2 bits of the TOS field.
 */
#define IPTOS_ECN_NOTECT        0x00    /* not-ECT */
#define IPTOS_ECN_ECT1          0x01    /* ECN-capable transport (1) */
#define IPTOS_ECN_ECT0          0x02    /* ECN-capable transport (0) */
#define IPTOS_ECN_CE            0x03    /* congestion experienced */
#define IPTOS_ECN_MASK          0x03    /* ECN field mask */

/*
 * Definitions for IP precedence (also in ip_tos) (hopefully unused)
 */
#define IPTOS_PREC_NETCONTROL           0xe0
#define IPTOS_PREC_INTERNETCONTROL      0xc0
#define IPTOS_PREC_CRITIC_ECP           0xa0
#define IPTOS_PREC_FLASHOVERRIDE        0x80
#define IPTOS_PREC_FLASH                0x60
#define IPTOS_PREC_IMMEDIATE            0x40
#define IPTOS_PREC_PRIORITY             0x20
#define IPTOS_PREC_ROUTINE              0x00

#ifdef PRIVATE
/*
 * Definitions of traffic class for use within wireless LAN.
 * Mainly used by AFP for backup. Not recommended for general use.
 */
#define IP_TCLASS_BE                    0x00    /* standard, best effort */
#define IP_TCLASS_BK                    0x20    /* Background, low priority */
#define IP_TCLASS_VI                    0x80    /* Interactive */
#define IP_TCLASS_VO                    0xc0    /* Signalling */

#endif
/*
 * 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 */
#define IPOPT_RA                148             /* router alert */

/*
 * 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_int   ipt_flg:4,              /* flags, see below */
	    ipt_oflw:4;                 /* overflow counter */
#endif
#if BYTE_ORDER == BIG_ENDIAN
	u_int   ipt_oflw:4,             /* overflow counter */
	    ipt_flg:4;                  /* flags, see below */
#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        3               /* 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       30              /* time to live for frags (seconds) */
#define IPTTLDEC        1               /* subtracted when forwarding */

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

#endif