1. 根目录:
2. include
3. uapi
4. linux
5. ip.h

/*
 * INET		An implementation of the TCP/IP protocol suite for the LINUX
 *		operating system.  INET is implemented using the  BSD Socket
 *		interface as the means of communication with the user level.
 *
 *		Definitions for the IP protocol.
 *
 * Version:	@(#)ip.h	1.0.2	04/28/93
 *
 * Authors:	Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
 *
 *		This program is free software; you can redistribute it and/or
 *		modify it under the terms of the GNU General Public License
 *		as published by the Free Software Foundation; either version
 *		2 of the License, or (at your option) any later version.
 */
#ifndef _UAPI_LINUX_IP_H
#define _UAPI_LINUX_IP_H
#include <linux/types.h>
#include <asm/byteorder.h>

#define IPTOS_TOS_MASK		0x1E
#define IPTOS_TOS(tos)		((tos)&IPTOS_TOS_MASK)
#define	IPTOS_LOWDELAY		0x10
#define	IPTOS_THROUGHPUT	0x08
#define	IPTOS_RELIABILITY	0x04
#define	IPTOS_MINCOST		0x02

#define IPTOS_PREC_MASK		0xE0
#define IPTOS_PREC(tos)		((tos)&IPTOS_PREC_MASK)
#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


/* IP options */
#define IPOPT_COPY		0x80
#define IPOPT_CLASS_MASK	0x60
#define IPOPT_NUMBER_MASK	0x1f

#define	IPOPT_COPIED(o)		((o)&IPOPT_COPY)
#define	IPOPT_CLASS(o)		((o)&IPOPT_CLASS_MASK)
#define	IPOPT_NUMBER(o)		((o)&IPOPT_NUMBER_MASK)

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

#define IPOPT_END	(0 |IPOPT_CONTROL)
#define IPOPT_NOOP	(1 |IPOPT_CONTROL)
#define IPOPT_SEC	(2 |IPOPT_CONTROL|IPOPT_COPY)
#define IPOPT_LSRR	(3 |IPOPT_CONTROL|IPOPT_COPY)
#define IPOPT_TIMESTAMP	(4 |IPOPT_MEASUREMENT)
#define IPOPT_CIPSO	(6 |IPOPT_CONTROL|IPOPT_COPY)
#define IPOPT_RR	(7 |IPOPT_CONTROL)
#define IPOPT_SID	(8 |IPOPT_CONTROL|IPOPT_COPY)
#define IPOPT_SSRR	(9 |IPOPT_CONTROL|IPOPT_COPY)
#define IPOPT_RA	(20|IPOPT_CONTROL|IPOPT_COPY)

#define IPVERSION	4
#define MAXTTL		255
#define IPDEFTTL	64

#define IPOPT_OPTVAL 0
#define IPOPT_OLEN   1
#define IPOPT_OFFSET 2
#define IPOPT_MINOFF 4
#define MAX_IPOPTLEN 40
#define IPOPT_NOP IPOPT_NOOP
#define IPOPT_EOL IPOPT_END
#define IPOPT_TS  IPOPT_TIMESTAMP

#define	IPOPT_TS_TSONLY		0		/* timestamps only */
#define	IPOPT_TS_TSANDADDR	1		/* timestamps and addresses */
#define	IPOPT_TS_PRESPEC	3		/* specified modules only */

#define IPV4_BEET_PHMAXLEN 8

struct iphdr {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u8	ihl:4,
		version:4;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u8	version:4,
  		ihl:4;
#else
#error	"Please fix <asm/byteorder.h>"
#endif
	__u8	tos;
	__be16	tot_len;
	__be16	id;
	__be16	frag_off;
	__u8	ttl;
	__u8	protocol;
	__sum16	check;
	__be32	saddr;
	__be32	daddr;
	/*The options start here. */
};


struct ip_auth_hdr {
	__u8  nexthdr;
	__u8  hdrlen;		/* This one is measured in 32 bit units! */
	__be16 reserved;
	__be32 spi;
	__be32 seq_no;		/* Sequence number */
	__u8  auth_data[0];	/* Variable len but >=4. Mind the 64 bit alignment! */
};

struct ip_esp_hdr {
	__be32 spi;
	__be32 seq_no;		/* Sequence number */
	__u8  enc_data[0];	/* Variable len but >=8. Mind the 64 bit alignment! */
};

struct ip_comp_hdr {
	__u8 nexthdr;
	__u8 flags;
	__be16 cpi;
};

struct ip_beet_phdr {
	__u8 nexthdr;
	__u8 hdrlen;
	__u8 padlen;
	__u8 reserved;
};

#endif /* _UAPI_LINUX_IP_H */