1. 根目录:
2. include
3. linux
4. in.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 of the Internet Protocol.
 *
 * Version:	@(#)in.h	1.0.1	04/21/93
 *
 * Authors:	Original taken from the GNU Project <netinet/in.h> file.
 *		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 _LINUX_IN_H
#define _LINUX_IN_H


#include <linux/errno.h>
#include <uapi/linux/in.h>

static inline int proto_ports_offset(int proto)
{
	switch (proto) {
	case IPPROTO_TCP:
	case IPPROTO_UDP:
	case IPPROTO_DCCP:
	case IPPROTO_ESP:	/* SPI */
	case IPPROTO_SCTP:
	case IPPROTO_UDPLITE:
		return 0;
	case IPPROTO_AH:	/* SPI */
		return 4;
	default:
		return -EINVAL;
	}
}

static inline bool ipv4_is_loopback(__be32 addr)
{
	return (addr & htonl(0xff000000)) == htonl(0x7f000000);
}

static inline bool ipv4_is_multicast(__be32 addr)
{
	return (addr & htonl(0xf0000000)) == htonl(0xe0000000);
}

static inline bool ipv4_is_local_multicast(__be32 addr)
{
	return (addr & htonl(0xffffff00)) == htonl(0xe0000000);
}

static inline bool ipv4_is_lbcast(__be32 addr)
{
	/* limited broadcast */
	return addr == htonl(INADDR_BROADCAST);
}

static inline bool ipv4_is_zeronet(__be32 addr)
{
	return (addr & htonl(0xff000000)) == htonl(0x00000000);
}

/* Special-Use IPv4 Addresses (RFC3330) */

static inline bool ipv4_is_private_10(__be32 addr)
{
	return (addr & htonl(0xff000000)) == htonl(0x0a000000);
}

static inline bool ipv4_is_private_172(__be32 addr)
{
	return (addr & htonl(0xfff00000)) == htonl(0xac100000);
}

static inline bool ipv4_is_private_192(__be32 addr)
{
	return (addr & htonl(0xffff0000)) == htonl(0xc0a80000);
}

static inline bool ipv4_is_linklocal_169(__be32 addr)
{
	return (addr & htonl(0xffff0000)) == htonl(0xa9fe0000);
}

static inline bool ipv4_is_anycast_6to4(__be32 addr)
{
	return (addr & htonl(0xffffff00)) == htonl(0xc0586300);
}

static inline bool ipv4_is_test_192(__be32 addr)
{
	return (addr & htonl(0xffffff00)) == htonl(0xc0000200);
}

static inline bool ipv4_is_test_198(__be32 addr)
{
	return (addr & htonl(0xfffe0000)) == htonl(0xc6120000);
}
#endif	/* _LINUX_IN_H */