/*-
 * SPDX-License-Identifier: BSD-2-Clause
 *
 * Copyright (c) 2012 Chelsio Communications, Inc.
 * All rights reserved.
 * Written by: Navdeep Parhar <np@FreeBSD.org>
 *
 * 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 AUTHOR 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 AUTHOR 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.
 */

#include "opt_inet.h"
#include "opt_inet6.h"

#include <sys/param.h>
#include <sys/eventhandler.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <sys/types.h>
#include <sys/sockopt.h>
#include <sys/sysctl.h>
#include <sys/socket.h>

#include <net/ethernet.h>
#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_types.h>
#include <net/if_vlan_var.h>
#include <net/if_llatbl.h>
#include <net/route.h>

#include <netinet/if_ether.h>
#include <netinet/in.h>
#include <netinet/in_pcb.h>
#include <netinet/in_var.h>
#include <netinet6/in6_var.h>
#include <netinet6/in6_pcb.h>
#include <netinet6/nd6.h>
#define TCPSTATES
#include <netinet/tcp.h>
#include <netinet/tcp_fsm.h>
#include <netinet/tcp_timer.h>
#include <netinet/tcp_var.h>
#include <netinet/tcp_syncache.h>
#include <netinet/tcp_offload.h>
#include <netinet/toecore.h>

static struct mtx toedev_lock;
static TAILQ_HEAD(, toedev) toedev_list;
static eventhandler_tag listen_start_eh;
static eventhandler_tag listen_stop_eh;
static eventhandler_tag lle_event_eh;

static int
toedev_connect(struct toedev *tod __unused, struct socket *so __unused,
    struct nhop_object *nh __unused, struct sockaddr *nam __unused)
{

        return (ENOTSUP);
}

static int
toedev_listen_start(struct toedev *tod __unused, struct tcpcb *tp __unused)
{

        return (ENOTSUP);
}

static int
toedev_listen_stop(struct toedev *tod __unused, struct tcpcb *tp __unused)
{

        return (ENOTSUP);
}

static void
toedev_input(struct toedev *tod __unused, struct tcpcb *tp __unused,
    struct mbuf *m)
{

        m_freem(m);
        return;
}

static void
toedev_rcvd(struct toedev *tod __unused, struct tcpcb *tp __unused)
{

        return;
}

static int
toedev_output(struct toedev *tod __unused, struct tcpcb *tp __unused)
{

        return (ENOTSUP);
}

static void
toedev_pcb_detach(struct toedev *tod __unused, struct tcpcb *tp __unused)
{

        return;
}

static void
toedev_l2_update(struct toedev *tod __unused, struct ifnet *ifp __unused,
    struct sockaddr *sa __unused, uint8_t *lladdr __unused,
    uint16_t vtag __unused)
{

        return;
}

static void
toedev_route_redirect(struct toedev *tod __unused, struct ifnet *ifp __unused,
    struct nhop_object *nh0 __unused, struct nhop_object *nh1 __unused)
{

        return;
}

static void
toedev_syncache_added(struct toedev *tod __unused, void *ctx __unused)
{

        return;
}

static void
toedev_syncache_removed(struct toedev *tod __unused, void *ctx __unused)
{

        return;
}

static int
toedev_syncache_respond(struct toedev *tod __unused, void *ctx __unused,
    struct mbuf *m)
{

        m_freem(m);
        return (0);
}

static void
toedev_offload_socket(struct toedev *tod __unused, void *ctx __unused,
    struct socket *so __unused)
{

        return;
}

static void
toedev_ctloutput(struct toedev *tod __unused, struct tcpcb *tp __unused,
    int sopt_dir __unused, int sopt_name __unused)
{

        return;
}

static void
toedev_tcp_info(struct toedev *tod __unused, const struct tcpcb *tp __unused,
    struct tcp_info *ti __unused)
{

        return;
}

static int
toedev_alloc_tls_session(struct toedev *tod __unused, struct tcpcb *tp __unused,
    struct ktls_session *tls __unused, int direction __unused)
{

        return (EINVAL);
}

static void
toedev_pmtu_update(struct toedev *tod __unused, struct tcpcb *tp __unused,
    tcp_seq seq __unused, int mtu __unused)
{

        return;
}

/*
 * Inform one or more TOE devices about a listening socket.
 */
static void
toe_listen_start(struct inpcb *inp, void *arg)
{
        struct toedev *t, *tod;
        struct tcpcb *tp;

        INP_WLOCK_ASSERT(inp);
        KASSERT(inp->inp_pcbinfo == &V_tcbinfo,
            ("%s: inp is not a TCP inp", __func__));

        if (inp->inp_flags & INP_DROPPED)
                return;

        tp = intotcpcb(inp);
        if (tp->t_state != TCPS_LISTEN)
                return;

        t = arg;
        mtx_lock(&toedev_lock);
        TAILQ_FOREACH(tod, &toedev_list, link) {
                if (t == NULL || t == tod)
                        tod->tod_listen_start(tod, tp);
        }
        mtx_unlock(&toedev_lock);
}

static void
toe_listen_start_event(void *arg __unused, struct tcpcb *tp)
{
        struct inpcb *inp = tptoinpcb(tp);

        INP_WLOCK_ASSERT(inp);
        KASSERT(tp->t_state == TCPS_LISTEN,
            ("%s: t_state %s", __func__, tcpstates[tp->t_state]));

        toe_listen_start(inp, NULL);
}

static void
toe_listen_stop_event(void *arg __unused, struct tcpcb *tp)
{
        struct toedev *tod;
#ifdef INVARIANTS
        struct inpcb *inp = tptoinpcb(tp);
#endif

        INP_WLOCK_ASSERT(inp);
        KASSERT(tp->t_state == TCPS_LISTEN,
            ("%s: t_state %s", __func__, tcpstates[tp->t_state]));

        mtx_lock(&toedev_lock);
        TAILQ_FOREACH(tod, &toedev_list, link)
            tod->tod_listen_stop(tod, tp);
        mtx_unlock(&toedev_lock);
}

/*
 * Fill up a freshly allocated toedev struct with reasonable defaults.
 */
void
init_toedev(struct toedev *tod)
{

        tod->tod_softc = NULL;

        /*
         * Provide no-op defaults so that the kernel can call any toedev
         * function without having to check whether the TOE driver supplied one
         * or not.
         */
        tod->tod_connect = toedev_connect;
        tod->tod_listen_start = toedev_listen_start;
        tod->tod_listen_stop = toedev_listen_stop;
        tod->tod_input = toedev_input;
        tod->tod_rcvd = toedev_rcvd;
        tod->tod_output = toedev_output;
        tod->tod_send_rst = toedev_output;
        tod->tod_send_fin = toedev_output;
        tod->tod_pcb_detach = toedev_pcb_detach;
        tod->tod_l2_update = toedev_l2_update;
        tod->tod_route_redirect = toedev_route_redirect;
        tod->tod_syncache_added = toedev_syncache_added;
        tod->tod_syncache_removed = toedev_syncache_removed;
        tod->tod_syncache_respond = toedev_syncache_respond;
        tod->tod_offload_socket = toedev_offload_socket;
        tod->tod_ctloutput = toedev_ctloutput;
        tod->tod_tcp_info = toedev_tcp_info;
        tod->tod_alloc_tls_session = toedev_alloc_tls_session;
        tod->tod_pmtu_update = toedev_pmtu_update;
}

/*
 * Register an active TOE device with the system.  This allows it to receive
 * notifications from the kernel.
 */
int
register_toedev(struct toedev *tod)
{
        struct toedev *t;

        mtx_lock(&toedev_lock);
        TAILQ_FOREACH(t, &toedev_list, link) {
                if (t == tod) {
                        mtx_unlock(&toedev_lock);
                        return (EEXIST);
                }
        }

        TAILQ_INSERT_TAIL(&toedev_list, tod, link);
        registered_toedevs++;
        mtx_unlock(&toedev_lock);

        inp_apply_all(&V_tcbinfo, toe_listen_start, tod);

        return (0);
}

/*
 * Remove the TOE device from the global list of active TOE devices.  It is the
 * caller's responsibility to ensure that the TOE device is quiesced prior to
 * this call.
 */
int
unregister_toedev(struct toedev *tod)
{
        struct toedev *t, *t2;
        int rc = ENODEV;

        mtx_lock(&toedev_lock);
        TAILQ_FOREACH_SAFE(t, &toedev_list, link, t2) {
                if (t == tod) {
                        TAILQ_REMOVE(&toedev_list, tod, link);
                        registered_toedevs--;
                        rc = 0;
                        break;
                }
        }
        KASSERT(registered_toedevs >= 0,
            ("%s: registered_toedevs (%d) < 0", __func__, registered_toedevs));
        mtx_unlock(&toedev_lock);
        return (rc);
}

void
toe_syncache_add(struct in_conninfo *inc, struct tcpopt *to, struct tcphdr *th,
    struct inpcb *inp, void *tod, void *todctx, uint8_t iptos)
{

        INP_RLOCK_ASSERT(inp);

        (void )syncache_add(inc, to, th, inp, inp->inp_socket, NULL, tod,
            todctx, iptos, htons(0));
}

int
toe_syncache_expand(struct in_conninfo *inc, struct tcpopt *to,
    struct tcphdr *th, struct socket **lsop)
{

        NET_EPOCH_ASSERT();

        return (syncache_expand(inc, to, th, lsop, NULL, htons(0)));
}

/*
 * General purpose check to see if a 4-tuple is in use by the kernel.  If a TCP
 * header (presumably for an incoming SYN) is also provided, an existing 4-tuple
 * in TIME_WAIT may be assassinated freeing it up for re-use.
 *
 * Note that the TCP header must have been run through tcp_fields_to_host() or
 * equivalent.
 */
int
toe_4tuple_check(struct in_conninfo *inc, struct tcphdr *th, struct ifnet *ifp)
{
        struct inpcb *inp;
        struct tcpcb *tp;

        if (inc->inc_flags & INC_ISIPV6) {
                inp = in6_pcblookup(&V_tcbinfo, &inc->inc6_faddr,
                    inc->inc_fport, &inc->inc6_laddr, inc->inc_lport,
                    INPLOOKUP_RLOCKPCB, ifp);
        } else {
                inp = in_pcblookup(&V_tcbinfo, inc->inc_faddr, inc->inc_fport,
                    inc->inc_laddr, inc->inc_lport, INPLOOKUP_RLOCKPCB, ifp);
        }
        if (inp != NULL) {
                INP_RLOCK_ASSERT(inp);

                tp = intotcpcb(inp);
                if (tp->t_state == TCPS_TIME_WAIT && th != NULL) {
                        if (!tcp_twcheck(inp, NULL, th, NULL, 0))
                                return (EADDRINUSE);
                } else {
                        INP_RUNLOCK(inp);
                        return (EADDRINUSE);
                }
        }

        return (0);
}

static void
toe_lle_event(void *arg __unused, struct llentry *lle, int evt)
{
        struct toedev *tod;
        struct ifnet *ifp;
        struct sockaddr *sa;
        uint8_t *lladdr;
        uint16_t vid, pcp;
        int family;
        struct sockaddr_in6 sin6;

        LLE_WLOCK_ASSERT(lle);

        ifp = lltable_get_ifp(lle->lle_tbl);
        family = lltable_get_af(lle->lle_tbl);

        if (family != AF_INET && family != AF_INET6)
                return;
        /*
         * Not interested if the interface's TOE capability is not enabled.
         */
        if ((family == AF_INET && !(ifp->if_capenable & IFCAP_TOE4)) ||
            (family == AF_INET6 && !(ifp->if_capenable & IFCAP_TOE6)))
                return;

        tod = TOEDEV(ifp);
        if (tod == NULL)
                return;

        sa = (struct sockaddr *)&sin6;
        lltable_fill_sa_entry(lle, sa);

        vid = 0xfff;
        pcp = 0;
        if (evt != LLENTRY_RESOLVED) {
                /*
                 * LLENTRY_TIMEDOUT, LLENTRY_DELETED, LLENTRY_EXPIRED all mean
                 * this entry is going to be deleted.
                 */

                lladdr = NULL;
        } else {
                KASSERT(lle->la_flags & LLE_VALID,
                    ("%s: %p resolved but not valid?", __func__, lle));

                lladdr = (uint8_t *)lle->ll_addr;
                VLAN_TAG(ifp, &vid);
                VLAN_PCP(ifp, &pcp);
        }

        tod->tod_l2_update(tod, ifp, sa, lladdr, EVL_MAKETAG(vid, pcp, 0));
}

/*
 * Returns 0 or EWOULDBLOCK on success (any other value is an error).  0 means
 * lladdr and vtag are valid on return, EWOULDBLOCK means the TOE driver's
 * tod_l2_update will be called later, when the entry is resolved or times out.
 */
int
toe_l2_resolve(struct toedev *tod, struct ifnet *ifp, struct sockaddr *sa,
    uint8_t *lladdr, uint16_t *vtag)
{
        int rc;
        uint16_t vid, pcp;

        switch (sa->sa_family) {
#ifdef INET
        case AF_INET:
                rc = arpresolve(ifp, 0, NULL, sa, lladdr, NULL, NULL);
                break;
#endif
#ifdef INET6
        case AF_INET6:
                rc = nd6_resolve(ifp, LLE_SF(AF_INET6, 0), NULL, sa, lladdr,
                    NULL, NULL);
                break;
#endif
        default:
                return (EPROTONOSUPPORT);
        }

        if (rc == 0) {
                vid = 0xfff;
                pcp = 0;
                if (ifp->if_type == IFT_L2VLAN) {
                        VLAN_TAG(ifp, &vid);
                        VLAN_PCP(ifp, &pcp);
                } else if (ifp->if_pcp != IFNET_PCP_NONE) {
                        vid = 0;
                        pcp = ifp->if_pcp;
                }
                *vtag = EVL_MAKETAG(vid, pcp, 0);
        }

        return (rc);
}

void
toe_connect_failed(struct toedev *tod, struct inpcb *inp, int err)
{

        NET_EPOCH_ASSERT();
        INP_WLOCK_ASSERT(inp);

        if (!(inp->inp_flags & INP_DROPPED)) {
                struct tcpcb *tp = intotcpcb(inp);

                KASSERT(tp->t_flags & TF_TOE,
                    ("%s: tp %p not offloaded.", __func__, tp));

                if (err == EAGAIN) {
                        /*
                         * Temporary failure during offload, take this PCB back.
                         * Detach from the TOE driver and do the rest of what
                         * TCP's pr_connect() would have done if the connection
                         * wasn't offloaded.
                         */

                        tod->tod_pcb_detach(tod, tp);
                        KASSERT(!(tp->t_flags & TF_TOE),
                            ("%s: tp %p still offloaded.", __func__, tp));
                        tcp_timer_activate(tp, TT_KEEP, TP_KEEPINIT(tp));
                        if (tcp_output(tp) < 0)
                                INP_WLOCK(inp); /* re-acquire */
                } else {
                        tp = tcp_drop(tp, err);
                        if (tp == NULL)
                                INP_WLOCK(inp); /* re-acquire */
                }
        }
        INP_WLOCK_ASSERT(inp);
}

static int
toecore_load(void)
{

        mtx_init(&toedev_lock, "toedev lock", NULL, MTX_DEF);
        TAILQ_INIT(&toedev_list);

        listen_start_eh = EVENTHANDLER_REGISTER(tcp_offload_listen_start,
            toe_listen_start_event, NULL, EVENTHANDLER_PRI_ANY);
        listen_stop_eh = EVENTHANDLER_REGISTER(tcp_offload_listen_stop,
            toe_listen_stop_event, NULL, EVENTHANDLER_PRI_ANY);
        lle_event_eh = EVENTHANDLER_REGISTER(lle_event, toe_lle_event, NULL,
            EVENTHANDLER_PRI_ANY);

        return (0);
}

static int
toecore_unload(void)
{

        mtx_lock(&toedev_lock);
        if (!TAILQ_EMPTY(&toedev_list)) {
                mtx_unlock(&toedev_lock);
                return (EBUSY);
        }

        EVENTHANDLER_DEREGISTER(tcp_offload_listen_start, listen_start_eh);
        EVENTHANDLER_DEREGISTER(tcp_offload_listen_stop, listen_stop_eh);
        EVENTHANDLER_DEREGISTER(lle_event, lle_event_eh);

        mtx_unlock(&toedev_lock);
        mtx_destroy(&toedev_lock);

        return (0);
}

static int
toecore_mod_handler(module_t mod, int cmd, void *arg)
{

        if (cmd == MOD_LOAD)
                return (toecore_load());

        if (cmd == MOD_UNLOAD)
                return (toecore_unload());

        return (EOPNOTSUPP);
}

static moduledata_t mod_data= {
        "toecore",
        toecore_mod_handler,
        0
};

MODULE_VERSION(toecore, 1);
DECLARE_MODULE(toecore, mod_data, SI_SUB_EXEC, SI_ORDER_ANY);