route.h

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/*
 * 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 router.
 *
 * Version: @(#)route.h 1.0.4   05/27/93
 *
 * Authors: Ross Biro
 *      Fred N. van Kempen, <[email protected]>
 * Fixes:
 *      Alan Cox    :   Reformatted. Added ip_rt_local()
 *      Alan Cox    :   Support for TCP parameters.
 *      Alexey Kuznetsov:   Major changes for new routing code.
 *      Mike McLagan    :   Routing by source
 *      Robert Olsson   :   Added rt_cache statistics
 *
 *      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 _ROUTE_H
#define _ROUTE_H

#include <net/dst.h>
#include <net/inetpeer.h>
#include <net/flow.h>
#include <net/inet_sock.h>
#include <linux/in_route.h>
#include <linux/rtnetlink.h>
#include <linux/rcupdate.h>
#include <linux/route.h>
#include <linux/ip.h>
#include <linux/cache.h>
#include <linux/security.h>

#define RTO_ONLINK  0x01

#define RT_CONN_FLAGS(sk)   (RT_TOS(inet_sk(sk)->tos) | sock_flag(sk, SOCK_LOCALROUTE))

struct fib_nh;
struct fib_info;
struct rtable {
    struct dst_entry    dst;

    int         rt_genid;
    unsigned int        rt_flags;
    __u16           rt_type;
    __u8            rt_is_input;
    __u8            rt_uses_gateway;

    int         rt_iif;

    /* Info on neighbour */
    __be32          rt_gateway;

    /* Miscellaneous cached information */
    u32         rt_pmtu;

    struct list_head    rt_uncached;
};

static inline bool rt_is_input_route(const struct rtable *rt)
{
    return rt->rt_is_input != 0;
}

static inline bool rt_is_output_route(const struct rtable *rt)
{
    return rt->rt_is_input == 0;
}

static inline __be32 rt_nexthop(const struct rtable *rt, __be32 daddr)
{
    if (rt->rt_gateway)
        return rt->rt_gateway;
    return daddr;
}

struct ip_rt_acct {
    __u32   o_bytes;
    __u32   o_packets;
    __u32   i_bytes;
    __u32   i_packets;
};

struct rt_cache_stat {
        unsigned int in_hit;
        unsigned int in_slow_tot;
        unsigned int in_slow_mc;
        unsigned int in_no_route;
        unsigned int in_brd;
        unsigned int in_martian_dst;
        unsigned int in_martian_src;
        unsigned int out_hit;
        unsigned int out_slow_tot;
        unsigned int out_slow_mc;
        unsigned int gc_total;
        unsigned int gc_ignored;
        unsigned int gc_goal_miss;
        unsigned int gc_dst_overflow;
        unsigned int in_hlist_search;
        unsigned int out_hlist_search;
};

extern struct ip_rt_acct __percpu *ip_rt_acct;

struct in_device;
extern int      ip_rt_init(void);
extern void     rt_cache_flush(struct net *net);
extern void     rt_flush_dev(struct net_device *dev);
extern struct rtable *__ip_route_output_key(struct net *, struct flowi4 *flp);
extern struct rtable *ip_route_output_flow(struct net *, struct flowi4 *flp,
                       struct sock *sk);
extern struct dst_entry *ipv4_blackhole_route(struct net *net, struct dst_entry *dst_orig);

static inline struct rtable *ip_route_output_key(struct net *net, struct flowi4 *flp)
{
    return ip_route_output_flow(net, flp, NULL);
}

static inline struct rtable *ip_route_output(struct net *net, __be32 daddr,
                         __be32 saddr, u8 tos, int oif)
{
    struct flowi4 fl4 = {
        .flowi4_oif = oif,
        .flowi4_tos = tos,
        .daddr = daddr,
        .saddr = saddr,
    };
    return ip_route_output_key(net, &fl4);
}

static inline struct rtable *ip_route_output_ports(struct net *net, struct flowi4 *fl4,
                           struct sock *sk,
                           __be32 daddr, __be32 saddr,
                           __be16 dport, __be16 sport,
                           __u8 proto, __u8 tos, int oif)
{
    flowi4_init_output(fl4, oif, sk ? sk->sk_mark : 0, tos,
               RT_SCOPE_UNIVERSE, proto,
               sk ? inet_sk_flowi_flags(sk) : 0,
               daddr, saddr, dport, sport);
    if (sk)
        security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
    return ip_route_output_flow(net, fl4, sk);
}

static inline struct rtable *ip_route_output_gre(struct net *net, struct flowi4 *fl4,
                         __be32 daddr, __be32 saddr,
                         __be32 gre_key, __u8 tos, int oif)
{
    memset(fl4, 0, sizeof(*fl4));
    fl4->flowi4_oif = oif;
    fl4->daddr = daddr;
    fl4->saddr = saddr;
    fl4->flowi4_tos = tos;
    fl4->flowi4_proto = IPPROTO_GRE;
    fl4->fl4_gre_key = gre_key;
    return ip_route_output_key(net, fl4);
}

extern int ip_route_input_noref(struct sk_buff *skb, __be32 dst, __be32 src,
                u8 tos, struct net_device *devin);

static inline int ip_route_input(struct sk_buff *skb, __be32 dst, __be32 src,
                 u8 tos, struct net_device *devin)
{
    int err;

    rcu_read_lock();
    err = ip_route_input_noref(skb, dst, src, tos, devin);
    if (!err)
        skb_dst_force(skb);
    rcu_read_unlock();

    return err;
}

extern void ipv4_update_pmtu(struct sk_buff *skb, struct net *net, u32 mtu,
                 int oif, u32 mark, u8 protocol, int flow_flags);
extern void ipv4_sk_update_pmtu(struct sk_buff *skb, struct sock *sk, u32 mtu);
extern void ipv4_redirect(struct sk_buff *skb, struct net *net,
              int oif, u32 mark, u8 protocol, int flow_flags);
extern void ipv4_sk_redirect(struct sk_buff *skb, struct sock *sk);
extern void ip_rt_send_redirect(struct sk_buff *skb);

extern unsigned int     inet_addr_type(struct net *net, __be32 addr);
extern unsigned int     inet_dev_addr_type(struct net *net, const struct net_device *dev, __be32 addr);
extern void     ip_rt_multicast_event(struct in_device *);
extern int      ip_rt_ioctl(struct net *, unsigned int cmd, void __user *arg);
extern void     ip_rt_get_source(u8 *src, struct sk_buff *skb, struct rtable *rt);
extern int      ip_rt_dump(struct sk_buff *skb,  struct netlink_callback *cb);

struct in_ifaddr;
extern void fib_add_ifaddr(struct in_ifaddr *);
extern void fib_del_ifaddr(struct in_ifaddr *, struct in_ifaddr *);

static inline void ip_rt_put(struct rtable * rt)
{
    if (rt)
        dst_release(&rt->dst);
}

#define IPTOS_RT_MASK   (IPTOS_TOS_MASK & ~3)

extern const __u8 ip_tos2prio[16];

static inline char rt_tos2priority(u8 tos)
{
    return ip_tos2prio[IPTOS_TOS(tos)>>1];
}

/* ip_route_connect() and ip_route_newports() work in tandem whilst
 * binding a socket for a new outgoing connection.
 *
 * In order to use IPSEC properly, we must, in the end, have a
 * route that was looked up using all available keys including source
 * and destination ports.
 *
 * However, if a source port needs to be allocated (the user specified
 * a wildcard source port) we need to obtain addressing information
 * in order to perform that allocation.
 *
 * So ip_route_connect() looks up a route using wildcarded source and
 * destination ports in the key, simply so that we can get a pair of
 * addresses to use for port allocation.
 *
 * Later, once the ports are allocated, ip_route_newports() will make
 * another route lookup if needed to make sure we catch any IPSEC
 * rules keyed on the port information.
 *
 * The callers allocate the flow key on their stack, and must pass in
 * the same flowi4 object to both the ip_route_connect() and the
 * ip_route_newports() calls.
 */

static inline void ip_route_connect_init(struct flowi4 *fl4, __be32 dst, __be32 src,
                     u32 tos, int oif, u8 protocol,
                     __be16 sport, __be16 dport,
                     struct sock *sk, bool can_sleep)
{
    __u8 flow_flags = 0;

    if (inet_sk(sk)->transparent)
        flow_flags |= FLOWI_FLAG_ANYSRC;
    if (can_sleep)
        flow_flags |= FLOWI_FLAG_CAN_SLEEP;

    flowi4_init_output(fl4, oif, sk->sk_mark, tos, RT_SCOPE_UNIVERSE,
               protocol, flow_flags, dst, src, dport, sport);
}

static inline struct rtable *ip_route_connect(struct flowi4 *fl4,
                          __be32 dst, __be32 src, u32 tos,
                          int oif, u8 protocol,
                          __be16 sport, __be16 dport,
                          struct sock *sk, bool can_sleep)
{
    struct net *net = sock_net(sk);
    struct rtable *rt;

    ip_route_connect_init(fl4, dst, src, tos, oif, protocol,
                  sport, dport, sk, can_sleep);

    if (!dst || !src) {
        rt = __ip_route_output_key(net, fl4);
        if (IS_ERR(rt))
            return rt;
        ip_rt_put(rt);
        flowi4_update_output(fl4, oif, tos, fl4->daddr, fl4->saddr);
    }
    security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
    return ip_route_output_flow(net, fl4, sk);
}

static inline struct rtable *ip_route_newports(struct flowi4 *fl4, struct rtable *rt,
                           __be16 orig_sport, __be16 orig_dport,
                           __be16 sport, __be16 dport,
                           struct sock *sk)
{
    if (sport != orig_sport || dport != orig_dport) {
        fl4->fl4_dport = dport;
        fl4->fl4_sport = sport;
        ip_rt_put(rt);
        flowi4_update_output(fl4, sk->sk_bound_dev_if,
                     RT_CONN_FLAGS(sk), fl4->daddr,
                     fl4->saddr);
        security_sk_classify_flow(sk, flowi4_to_flowi(fl4));
        return ip_route_output_flow(sock_net(sk), fl4, sk);
    }
    return rt;
}

static inline int inet_iif(const struct sk_buff *skb)
{
    int iif = skb_rtable(skb)->rt_iif;

    if (iif)
        return iif;
    return skb->skb_iif;
}

extern int sysctl_ip_default_ttl;

static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
{
    int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);

    if (hoplimit == 0)
        hoplimit = sysctl_ip_default_ttl;
    return hoplimit;
}

#endif  /* _ROUTE_H */