/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1982, 1986, 1993
 *      The Regents of the University of California.  All rights reserved.
 *
 * 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.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

/*
 * Loopback interface driver for protocol testing and timing.
 */

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/mbuf.h>
#include <sys/module.h>
#include <machine/bus.h>
#include <sys/rman.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/if_private.h>
#include <net/if_clone.h>
#include <net/if_types.h>
#include <net/netisr.h>
#include <net/route.h>
#include <net/bpf.h>
#include <net/vnet.h>

#ifdef  INET
#include <netinet/in.h>
#include <netinet/in_var.h>
#endif

#ifdef INET6
#ifndef INET
#include <netinet/in.h>
#endif
#include <netinet6/in6_var.h>
#include <netinet/ip6.h>
#endif

#include <security/mac/mac_framework.h>

#ifdef TINY_LOMTU
#define LOMTU   (1024+512)
#elif defined(LARGE_LOMTU)
#define LOMTU   131072
#else
#define LOMTU   16384
#endif

#define LO_CSUM_FEATURES        (CSUM_IP | CSUM_TCP | CSUM_UDP | CSUM_SCTP)
#define LO_CSUM_FEATURES6       (CSUM_TCP_IPV6 | CSUM_UDP_IPV6 | CSUM_SCTP_IPV6)
#define LO_CSUM_SET             (CSUM_DATA_VALID | CSUM_DATA_VALID_IPV6 | \
                                    CSUM_PSEUDO_HDR | \
                                    CSUM_IP_CHECKED | CSUM_IP_VALID | \
                                    CSUM_SCTP_VALID)

static int      loioctl(struct ifnet *, u_long, caddr_t);
static int      looutput(struct ifnet *ifp, struct mbuf *m,
                    const struct sockaddr *dst, struct route *ro);

VNET_DEFINE(struct ifnet *, loif);      /* Used externally */
VNET_DEFINE_STATIC(struct if_clone *, lo_cloner);
#define V_lo_cloner             VNET(lo_cloner)

static const char loname[] = "lo";

static int
lo_clone_destroy(struct if_clone *ifc, struct ifnet *ifp, uint32_t flags)
{
        if (ifp->if_dunit == 0 && (flags & IFC_F_FORCE) == 0)
                return (EINVAL);

#ifndef VIMAGE
        /* XXX: destroying lo0 will lead to panics. */
        KASSERT(V_loif != ifp, ("%s: destroying lo0", __func__));
#endif

        bpfdetach(ifp);
        if_detach(ifp);
        if_free(ifp);

        return (0);
}

static int
lo_clone_create(struct if_clone *ifc, char *name, size_t len,
    struct ifc_data *ifd, struct ifnet **ifpp)
{
        struct ifnet *ifp;

        ifp = if_alloc(IFT_LOOP);
        if_initname(ifp, loname, ifd->unit);
        ifp->if_mtu = LOMTU;
        ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
        ifp->if_ioctl = loioctl;
        ifp->if_output = looutput;
        ifp->if_snd.ifq_maxlen = ifqmaxlen;
        ifp->if_capabilities = ifp->if_capenable =
            IFCAP_HWCSUM | IFCAP_HWCSUM_IPV6 | IFCAP_LINKSTATE;
        ifp->if_hwassist = LO_CSUM_FEATURES | LO_CSUM_FEATURES6;
        if_attach(ifp);
        bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
        *ifpp = ifp;

        return (0);
}

static void
vnet_loif_init(const void *unused __unused)
{
        struct if_clone_addreq req = {
                .create_f = lo_clone_create,
                .destroy_f = lo_clone_destroy,
                .flags = IFC_F_AUTOUNIT,
        };
        V_lo_cloner = ifc_attach_cloner(loname, &req);
        struct ifc_data ifd = { .unit = 0 };
        ifc_create_ifp(loname, &ifd, &V_loif);
}
VNET_SYSINIT(vnet_loif_init, SI_SUB_PROTO_IF, SI_ORDER_ANY,
    vnet_loif_init, NULL);

#ifdef VIMAGE
static void
vnet_loif_uninit(const void *unused __unused)
{

        ifc_detach_cloner(V_lo_cloner);
        V_loif = NULL;
}
VNET_SYSUNINIT(vnet_loif_uninit, SI_SUB_INIT_IF, SI_ORDER_SECOND,
    vnet_loif_uninit, NULL);
#endif

static int
loop_modevent(module_t mod, int type, void *data)
{

        switch (type) {
        case MOD_LOAD:
                break;

        case MOD_UNLOAD:
                printf("loop module unload - not possible for this module type\n");
                return (EINVAL);

        default:
                return (EOPNOTSUPP);
        }
        return (0);
}

static moduledata_t loop_mod = {
        "if_lo",
        loop_modevent,
        0
};

DECLARE_MODULE(if_lo, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);

static int
looutput(struct ifnet *ifp, struct mbuf *m, const struct sockaddr *dst,
    struct route *ro)
{
        u_int32_t af;
#ifdef MAC
        int error;
#endif

        M_ASSERTPKTHDR(m); /* check if we have the packet header */

#ifdef MAC
        error = mac_ifnet_check_transmit(ifp, m);
        if (error) {
                m_freem(m);
                return (error);
        }
#endif

        if (ro != NULL && ro->ro_flags & (RT_REJECT|RT_BLACKHOLE)) {
                m_freem(m);
                return (ro->ro_flags & RT_BLACKHOLE ? 0 : EHOSTUNREACH);
        }

        if_inc_counter(ifp, IFCOUNTER_OPACKETS, 1);
        if_inc_counter(ifp, IFCOUNTER_OBYTES, m->m_pkthdr.len);

        M_HASHTYPE_CLEAR(m);

        /* BPF writes need to be handled specially. */
        if (dst->sa_family == AF_UNSPEC || dst->sa_family == pseudo_AF_HDRCMPLT)
                bcopy(dst->sa_data, &af, sizeof(af));
        else
                af = RO_GET_FAMILY(ro, dst);

#if 1   /* XXX */
        switch (af) {
        case AF_INET:
                if (ifp->if_capenable & IFCAP_RXCSUM) {
                        m->m_pkthdr.csum_data = 0xffff;
                        m->m_pkthdr.csum_flags = LO_CSUM_SET;
                }
                m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES;
                break;
        case AF_INET6:
#if 0
                /*
                 * XXX-BZ for now always claim the checksum is good despite
                 * any interface flags.   This is a workaround for 9.1-R and
                 * a proper solution ought to be sought later.
                 */
                if (ifp->if_capenable & IFCAP_RXCSUM_IPV6) {
                        m->m_pkthdr.csum_data = 0xffff;
                        m->m_pkthdr.csum_flags = LO_CSUM_SET;
                }
#else
                m->m_pkthdr.csum_data = 0xffff;
                m->m_pkthdr.csum_flags = LO_CSUM_SET;
#endif
                m->m_pkthdr.csum_flags &= ~LO_CSUM_FEATURES6;
                break;
        default:
                printf("looutput: af=%d unexpected\n", af);
                m_freem(m);
                return (EAFNOSUPPORT);
        }
#endif
        return (if_simloop(ifp, m, af, 0));
}

/*
 * if_simloop()
 *
 * This function is to support software emulation of hardware loopback,
 * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
 * hear their own broadcasts, we create a copy of the packet that we
 * would normally receive via a hardware loopback.
 *
 * This function expects the packet to include the media header of length hlen.
 */
int
if_simloop(struct ifnet *ifp, struct mbuf *m, int af, int hlen)
{
        int isr;

        M_ASSERTPKTHDR(m);
        m_tag_delete_nonpersistent(m);
        m->m_pkthdr.rcvif = ifp;

#ifdef MAC
        mac_ifnet_create_mbuf(ifp, m);
#endif

        /*
         * Let BPF see incoming packet in the following manner:
         *  - Emulated packet loopback for a simplex interface
         *    (net/if_ethersubr.c)
         *      -> passes it to ifp's BPF
         *  - IPv4/v6 multicast packet loopback (netinet(6)/ip(6)_output.c)
         *      -> not passes it to any BPF
         *  - Normal packet loopback from myself to myself (net/if_loop.c)
         *      -> passes to lo0's BPF (even in case of IPv6, where ifp!=lo0)
         */
        if (hlen > 0) {
                if (bpf_peers_present(ifp->if_bpf)) {
                        bpf_mtap(ifp->if_bpf, m);
                }
        } else {
                if (bpf_peers_present(V_loif->if_bpf)) {
                        if ((m->m_flags & M_MCAST) == 0 || V_loif == ifp) {
                                /* XXX beware sizeof(af) != 4 */
                                u_int32_t af1 = af;

                                /*
                                 * We need to prepend the address family.
                                 */
                                bpf_mtap2(V_loif->if_bpf, &af1, sizeof(af1), m);
                        }
                }
        }

        /* Strip away media header */
        if (hlen > 0) {
                m_adj(m, hlen);
#ifndef __NO_STRICT_ALIGNMENT
                /*
                 * Some archs do not like unaligned data, so
                 * we move data down in the first mbuf.
                 */
                if (mtod(m, vm_offset_t) & 3) {
                        KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
                        bcopy(m->m_data,
                            (char *)(mtod(m, vm_offset_t)
                                - (mtod(m, vm_offset_t) & 3)),
                            m->m_len);
                        m->m_data -= (mtod(m,vm_offset_t) & 3);
                }
#endif
        }

        /* Deliver to upper layer protocol */
        switch (af) {
#ifdef INET
        case AF_INET:
                isr = NETISR_IP;
                break;
#endif
#ifdef INET6
        case AF_INET6:
                m->m_flags |= M_LOOP;
                isr = NETISR_IPV6;
                break;
#endif
        default:
                printf("if_simloop: can't handle af=%d\n", af);
                m_freem(m);
                return (EAFNOSUPPORT);
        }
        if_inc_counter(ifp, IFCOUNTER_IPACKETS, 1);
        if_inc_counter(ifp, IFCOUNTER_IBYTES, m->m_pkthdr.len);
        netisr_queue(isr, m);   /* mbuf is free'd on failure. */
        return (0);
}

/*
 * Process an ioctl request.
 */
static int
loioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
{
        struct ifreq *ifr = (struct ifreq *)data;
        int error = 0, mask;

        switch (cmd) {
        case SIOCSIFADDR:
                ifp->if_flags |= IFF_UP;
                ifp->if_drv_flags |= IFF_DRV_RUNNING;
                if_link_state_change(ifp, LINK_STATE_UP);
                /*
                 * Everything else is done at a higher level.
                 */
                break;

        case SIOCADDMULTI:
        case SIOCDELMULTI:
                if (ifr == NULL) {
                        error = EAFNOSUPPORT;           /* XXX */
                        break;
                }
                switch (ifr->ifr_addr.sa_family) {
#ifdef INET
                case AF_INET:
                        break;
#endif
#ifdef INET6
                case AF_INET6:
                        break;
#endif

                default:
                        error = EAFNOSUPPORT;
                        break;
                }
                break;

        case SIOCSIFMTU:
                ifp->if_mtu = ifr->ifr_mtu;
                break;

        case SIOCSIFFLAGS:
                if_link_state_change(ifp, (ifp->if_flags & IFF_UP) ?
                    LINK_STATE_UP: LINK_STATE_DOWN);
                break;

        case SIOCSIFCAP:
                mask = ifp->if_capenable ^ ifr->ifr_reqcap;
                if ((mask & IFCAP_RXCSUM) != 0)
                        ifp->if_capenable ^= IFCAP_RXCSUM;
                if ((mask & IFCAP_TXCSUM) != 0)
                        ifp->if_capenable ^= IFCAP_TXCSUM;
                if ((mask & IFCAP_RXCSUM_IPV6) != 0) {
#if 0
                        ifp->if_capenable ^= IFCAP_RXCSUM_IPV6;
#else
                        error = EOPNOTSUPP;
                        break;
#endif
                }
                if ((mask & IFCAP_TXCSUM_IPV6) != 0) {
#if 0
                        ifp->if_capenable ^= IFCAP_TXCSUM_IPV6;
#else
                        error = EOPNOTSUPP;
                        break;
#endif
                }
                ifp->if_hwassist = 0;
                if (ifp->if_capenable & IFCAP_TXCSUM)
                        ifp->if_hwassist = LO_CSUM_FEATURES;
#if 0
                if (ifp->if_capenable & IFCAP_TXCSUM_IPV6)
                        ifp->if_hwassist |= LO_CSUM_FEATURES6;
#endif
                break;

        default:
                error = EINVAL;
        }
        return (error);
}