/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 1998 The NetBSD Foundation, Inc.
 * Copyright (c) 2014 Andrey V. Elsukov <ae@FreeBSD.org>
 * All rights reserved
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Heiko W.Rupp <hwr@pilhuhn.de>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * $NetBSD: if_gre.h,v 1.13 2003/11/10 08:51:52 wiz Exp $
 */

#ifndef _NET_IF_GRE_H_
#define _NET_IF_GRE_H_

#ifdef _KERNEL
/* GRE header according to RFC 2784 and RFC 2890 */
struct grehdr {
        uint16_t        gre_flags;      /* GRE flags */
#define GRE_FLAGS_CP    0x8000          /* checksum present */
#define GRE_FLAGS_KP    0x2000          /* key present */
#define GRE_FLAGS_SP    0x1000          /* sequence present */
#define GRE_FLAGS_MASK  (GRE_FLAGS_CP|GRE_FLAGS_KP|GRE_FLAGS_SP)
        uint16_t        gre_proto;      /* protocol type */
        uint32_t        gre_opts[0];    /* optional fields */
} __packed;

#ifdef INET
struct greip {
        struct ip       gi_ip;
        struct grehdr   gi_gre;
} __packed;

struct greudp {
        struct ip       gi_ip;
        struct udphdr   gi_udp;
        struct grehdr   gi_gre;
} __packed;
#endif /* INET */

#ifdef INET6
struct greip6 {
        struct ip6_hdr  gi6_ip6;
        struct grehdr   gi6_gre;
} __packed;

struct greudp6 {
        struct ip6_hdr  gi6_ip6;
        struct udphdr   gi6_udp;
        struct grehdr   gi6_gre;
} __packed;
#endif /* INET6 */

CK_LIST_HEAD(gre_list, gre_softc);
CK_LIST_HEAD(gre_sockets, gre_socket);
struct gre_socket {
        struct socket           *so;
        struct gre_list         list;
        CK_LIST_ENTRY(gre_socket) chain;
        struct epoch_context    epoch_ctx;
};

struct gre_softc {
        struct ifnet            *gre_ifp;
        int                     gre_family;     /* AF of delivery header */
        uint32_t                gre_iseq;
        uint32_t                gre_oseq;
        uint32_t                gre_key;
        uint32_t                gre_options;
        uint32_t                gre_csumflags;
        uint32_t                gre_port;
        u_int                   gre_fibnum;
        u_int                   gre_hlen;       /* header size */
        union {
                void            *hdr;
#ifdef INET
                struct greip    *iphdr;
                struct greudp   *udphdr;
#endif
#ifdef INET6
                struct greip6   *ip6hdr;
                struct greudp6  *udp6hdr;
#endif
        } gre_uhdr;
        struct gre_socket       *gre_so;

        CK_LIST_ENTRY(gre_softc) chain;
        CK_LIST_ENTRY(gre_softc) srchash;
};

MALLOC_DECLARE(M_GRE);

#ifndef GRE_HASH_SIZE
#define GRE_HASH_SIZE   (1 << 4)
#endif

#define GRE2IFP(sc)             ((sc)->gre_ifp)
#define GRE_RLOCK_TRACKER       struct epoch_tracker gre_et
#define GRE_RLOCK()             epoch_enter_preempt(net_epoch_preempt, &gre_et)
#define GRE_RUNLOCK()           epoch_exit_preempt(net_epoch_preempt, &gre_et)
#define GRE_WAIT()              epoch_wait_preempt(net_epoch_preempt)

#define gre_hdr                 gre_uhdr.hdr
#define gre_iphdr               gre_uhdr.iphdr
#define gre_ip6hdr              gre_uhdr.ip6hdr
#define gre_udphdr              gre_uhdr.udphdr
#define gre_udp6hdr             gre_uhdr.udp6hdr

#define gre_oip                 gre_iphdr->gi_ip
#define gre_udp                 gre_udphdr->gi_udp
#define gre_oip6                gre_ip6hdr->gi6_ip6
#define gre_udp6                gre_udp6hdr->gi6_udp

struct gre_list *gre_hashinit(void);
void gre_hashdestroy(struct gre_list *);

int     gre_input(struct mbuf *, int, int, void *);
void    gre_update_hdr(struct gre_softc *, struct grehdr *);
void    gre_update_udphdr(struct gre_softc *, struct udphdr *, uint16_t);
void    gre_sofree(epoch_context_t);

void    in_gre_init(void);
void    in_gre_uninit(void);
int     in_gre_setopts(struct gre_softc *, u_long, uint32_t);
int     in_gre_ioctl(struct gre_softc *, u_long, caddr_t);
int     in_gre_output(struct mbuf *, int, int);

void    in6_gre_init(void);
void    in6_gre_uninit(void);
int     in6_gre_setopts(struct gre_softc *, u_long, uint32_t);
int     in6_gre_ioctl(struct gre_softc *, u_long, caddr_t);
int     in6_gre_output(struct mbuf *, int, int, uint32_t);
/*
 * CISCO uses special type for GRE tunnel created as part of WCCP
 * connection, while in fact those packets are just IPv4 encapsulated
 * into GRE.
 */
#define ETHERTYPE_WCCP          0x883E
#endif /* _KERNEL */

#define GRESADDRS       _IOW('i', 101, struct ifreq)
#define GRESADDRD       _IOW('i', 102, struct ifreq)
#define GREGADDRS       _IOWR('i', 103, struct ifreq)
#define GREGADDRD       _IOWR('i', 104, struct ifreq)
#define GRESPROTO       _IOW('i' , 105, struct ifreq)
#define GREGPROTO       _IOWR('i', 106, struct ifreq)

#define GREGKEY         _IOWR('i', 107, struct ifreq)
#define GRESKEY         _IOW('i', 108, struct ifreq)
#define GREGOPTS        _IOWR('i', 109, struct ifreq)
#define GRESOPTS        _IOW('i', 110, struct ifreq)
#define GREGPORT        _IOWR('i', 111, struct ifreq)
#define GRESPORT        _IOW('i', 112, struct ifreq)

/* GRE-in-UDP encapsulation destination port as defined in RFC8086 */
#define GRE_UDPPORT             4754

#define GRE_ENABLE_CSUM         0x0001
#define GRE_ENABLE_SEQ          0x0002
#define GRE_UDPENCAP            0x0004
#define GRE_OPTMASK             (GRE_ENABLE_CSUM|GRE_ENABLE_SEQ|GRE_UDPENCAP)

#endif /* _NET_IF_GRE_H_ */