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

#ifndef _LINUX_IN_ROUTE_H
#define _LINUX_IN_ROUTE_H

/* IPv4 routing cache flags */

#define RTCF_DEAD	RTNH_F_DEAD
#define RTCF_ONLINK	RTNH_F_ONLINK

/* Obsolete flag. About to be deleted */
#define RTCF_NOPMTUDISC RTM_F_NOPMTUDISC

#define RTCF_NOTIFY	0x00010000
#define RTCF_DIRECTDST	0x00020000 /* unused */
#define RTCF_REDIRECTED	0x00040000
#define RTCF_TPROXY	0x00080000 /* unused */

#define RTCF_FAST	0x00200000 /* unused */
#define RTCF_MASQ	0x00400000 /* unused */
#define RTCF_SNAT	0x00800000 /* unused */
#define RTCF_DOREDIRECT 0x01000000
#define RTCF_DIRECTSRC	0x04000000
#define RTCF_DNAT	0x08000000
#define RTCF_BROADCAST	0x10000000
#define RTCF_MULTICAST	0x20000000
#define RTCF_REJECT	0x40000000 /* unused */
#define RTCF_LOCAL	0x80000000

#define RTCF_NAT	(RTCF_DNAT|RTCF_SNAT)

#define RT_TOS(tos)	((tos)&IPTOS_TOS_MASK)

#endif /* _LINUX_IN_ROUTE_H */