/* SPDX-License-Identifier: GPL-2.0 */
#ifndef _NET_IP6_TUNNEL_H
#define _NET_IP6_TUNNEL_H

#include <linux/ipv6.h>
#include <linux/netdevice.h>
#include <linux/if_tunnel.h>
#include <linux/ip6_tunnel.h>
#include <net/ip_tunnels.h>
#include <net/dst_cache.h>

#define IP6TUNNEL_ERR_TIMEO (30*HZ)

/* capable of sending packets */
#define IP6_TNL_F_CAP_XMIT 0x10000
/* capable of receiving packets */
#define IP6_TNL_F_CAP_RCV 0x20000
/* determine capability on a per-packet basis */
#define IP6_TNL_F_CAP_PER_PACKET 0x40000

struct __ip6_tnl_parm {
        char name[IFNAMSIZ];    /* name of tunnel device */
        int link;               /* ifindex of underlying L2 interface */
        __u8 proto;             /* tunnel protocol */
        __u8 encap_limit;       /* encapsulation limit for tunnel */
        __u8 hop_limit;         /* hop limit for tunnel */
        bool collect_md;
        __be32 flowinfo;        /* traffic class and flowlabel for tunnel */
        __u32 flags;            /* tunnel flags */
        struct in6_addr laddr;  /* local tunnel end-point address */
        struct in6_addr raddr;  /* remote tunnel end-point address */

        IP_TUNNEL_DECLARE_FLAGS(i_flags);
        IP_TUNNEL_DECLARE_FLAGS(o_flags);
        __be32                  i_key;
        __be32                  o_key;

        __u32                   fwmark;
        __u32                   index;  /* ERSPAN type II index */
        __u8                    erspan_ver;     /* ERSPAN version */
        __u8                    dir;    /* direction */
        __u16                   hwid;   /* hwid */
};

/* IPv6 tunnel */
struct ip6_tnl {
        struct ip6_tnl __rcu *next;     /* next tunnel in list */
        struct net_device *dev; /* virtual device associated with tunnel */
        netdevice_tracker dev_tracker;
        struct net *net;        /* netns for packet i/o */
        struct __ip6_tnl_parm parms;    /* tunnel configuration parameters */
        struct flowi fl;        /* flowi template for xmit */
        struct dst_cache dst_cache;     /* cached dst */
        struct gro_cells gro_cells;

        int err_count;
        unsigned long err_time;

        /* These fields used only by GRE */
        __u32 i_seqno;  /* The last seen seqno  */
        atomic_t o_seqno;       /* The last output seqno */
        int hlen;       /* tun_hlen + encap_hlen */
        int tun_hlen;   /* Precalculated header length */
        int encap_hlen; /* Encap header length (FOU,GUE) */
        struct ip_tunnel_encap encap;
        int mlink;
};

struct ip6_tnl_encap_ops {
        size_t (*encap_hlen)(struct ip_tunnel_encap *e);
        int (*build_header)(struct sk_buff *skb, struct ip_tunnel_encap *e,
                            u8 *protocol, struct flowi6 *fl6);
        int (*err_handler)(struct sk_buff *skb, struct inet6_skb_parm *opt,
                           u8 type, u8 code, int offset, __be32 info);
};

#ifdef CONFIG_INET

extern const struct ip6_tnl_encap_ops __rcu *
                ip6tun_encaps[MAX_IPTUN_ENCAP_OPS];

int ip6_tnl_encap_add_ops(const struct ip6_tnl_encap_ops *ops,
                          unsigned int num);
int ip6_tnl_encap_del_ops(const struct ip6_tnl_encap_ops *ops,
                          unsigned int num);
int ip6_tnl_encap_setup(struct ip6_tnl *t,
                        struct ip_tunnel_encap *ipencap);

static inline int ip6_encap_hlen(struct ip_tunnel_encap *e)
{
        const struct ip6_tnl_encap_ops *ops;
        int hlen = -EINVAL;

        if (e->type == TUNNEL_ENCAP_NONE)
                return 0;

        if (e->type >= MAX_IPTUN_ENCAP_OPS)
                return -EINVAL;

        rcu_read_lock();
        ops = rcu_dereference(ip6tun_encaps[e->type]);
        if (likely(ops && ops->encap_hlen))
                hlen = ops->encap_hlen(e);
        rcu_read_unlock();

        return hlen;
}

static inline int ip6_tnl_encap(struct sk_buff *skb, struct ip6_tnl *t,
                                u8 *protocol, struct flowi6 *fl6)
{
        const struct ip6_tnl_encap_ops *ops;
        int ret = -EINVAL;

        if (t->encap.type == TUNNEL_ENCAP_NONE)
                return 0;

        if (t->encap.type >= MAX_IPTUN_ENCAP_OPS)
                return -EINVAL;

        rcu_read_lock();
        ops = rcu_dereference(ip6tun_encaps[t->encap.type]);
        if (likely(ops && ops->build_header))
                ret = ops->build_header(skb, &t->encap, protocol, fl6);
        rcu_read_unlock();

        return ret;
}

/* Tunnel encapsulation limit destination sub-option */

struct ipv6_tlv_tnl_enc_lim {
        __u8 type;              /* type-code for option         */
        __u8 length;            /* option length                */
        __u8 encap_limit;       /* tunnel encapsulation limit   */
} __packed;

int ip6_tnl_rcv_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
                const struct in6_addr *raddr);
int ip6_tnl_rcv(struct ip6_tnl *tunnel, struct sk_buff *skb,
                const struct tnl_ptk_info *tpi, struct metadata_dst *tun_dst,
                bool log_ecn_error);
int ip6_tnl_xmit_ctl(struct ip6_tnl *t, const struct in6_addr *laddr,
                     const struct in6_addr *raddr);
int ip6_tnl_xmit(struct sk_buff *skb, struct net_device *dev, __u8 dsfield,
                 struct flowi6 *fl6, int encap_limit, __u32 *pmtu, __u8 proto);
__u16 ip6_tnl_parse_tlv_enc_lim(struct sk_buff *skb, __u8 *raw);
__u32 ip6_tnl_get_cap(struct ip6_tnl *t, const struct in6_addr *laddr,
                             const struct in6_addr *raddr);
struct net *ip6_tnl_get_link_net(const struct net_device *dev);
int ip6_tnl_get_iflink(const struct net_device *dev);
int ip6_tnl_change_mtu(struct net_device *dev, int new_mtu);

static inline void ip6tunnel_xmit(struct sock *sk, struct sk_buff *skb,
                                  struct net_device *dev, u16 ip6cb_flags)
{
        int pkt_len, err;

        if (unlikely(dev_recursion_level() > IP_TUNNEL_RECURSION_LIMIT)) {
                if (dev) {
                        net_crit_ratelimited("Dead loop on virtual device %s, fix it urgently!\n",
                                             dev->name);
                        DEV_STATS_INC(dev, tx_errors);
                }
                kfree_skb(skb);
                return;
        }

        dev_xmit_recursion_inc();

        memset(skb->cb, 0, sizeof(struct inet6_skb_parm));
        IP6CB(skb)->flags = ip6cb_flags;
        pkt_len = skb->len - skb_inner_network_offset(skb);
        err = ip6_local_out(skb_dst_dev_net(skb), sk, skb);

        if (dev) {
                if (unlikely(net_xmit_eval(err)))
                        pkt_len = -1;
                iptunnel_xmit_stats(dev, pkt_len);
        }

        dev_xmit_recursion_dec();
}
#endif
#endif