/*
 * 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.
 *
 *      @(#)if_loop.c   8.1 (Berkeley) 6/10/93
 * $FreeBSD: src/sys/net/if_loop.c,v 1.47.2.9 2004/02/08 08:40:24 silby Exp $
 */

/*
 * Loopback interface driver for protocol testing and timing.
 */
#include "use_loop.h"

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

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/sockio.h>

#include <net/if.h>
#include <net/if_types.h>
#include <net/if_clone.h>
#include <net/ifq_var.h>
#include <net/netisr.h>
#include <net/route.h>
#include <net/bpf.h>
#include <net/bpfdesc.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

static int      lo_clone_create(struct if_clone *, int, caddr_t, caddr_t);
static int      lo_clone_destroy(struct ifnet *);

static int      lo_output(struct ifnet *, struct mbuf *, struct sockaddr *,
                    struct rtentry *);
static int      lo_ioctl(struct ifnet *, u_long, caddr_t, struct ucred *);
static void     lo_rtrequest(int, struct rtentry *);
#ifdef ALTQ
static void     lo_altqstart(struct ifnet *, struct ifaltq_subque *);
#endif

#if defined(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_UDP | CSUM_TCP)

struct ifnet    *loif;

static struct if_clone lo_cloner = IF_CLONE_INITIALIZER("lo",
    lo_clone_create, lo_clone_destroy, NLOOP, IF_MAXUNIT);

static void
lo_sysinit(void *dummy __unused)
{
        if_clone_attach(&lo_cloner);
}
SYSINIT(lo_sysinit, SI_SUB_PSEUDO, SI_ORDER_ANY, lo_sysinit, NULL);

static int
lo_clone_create(struct if_clone *ifc, int unit,
                caddr_t params __unused, caddr_t data __unused)
{
        struct ifnet *ifp;

        ifp = kmalloc(sizeof(*ifp), M_IFNET, M_WAITOK | M_ZERO);
        if_initname(ifp, ifc->ifc_name, unit);
        ifp->if_mtu = LOMTU;
        ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
        ifp->if_capabilities = IFCAP_HWCSUM | IFCAP_RSS;
        ifp->if_hwassist = LO_CSUM_FEATURES;
        ifp->if_capenable = ifp->if_capabilities;
        ifp->if_ioctl = lo_ioctl;
        ifp->if_output = lo_output;
        ifp->if_type = IFT_LOOP;
        ifq_set_maxlen(&ifp->if_snd, ifqmaxlen);
        ifq_set_ready(&ifp->if_snd);
#ifdef ALTQ
        ifp->if_start = lo_altqstart;
#endif
        if_attach(ifp, NULL);
        bpfattach(ifp, DLT_NULL, sizeof(uint32_t));

        if (loif == NULL) {
                KASSERT(unit == 0, ("loif is %s", ifp->if_xname));
                loif = ifp;
        }
        return (0);
}

static int
lo_clone_destroy(struct ifnet *ifp)
{
        if (loif == ifp)
                return (EPERM);

        bpfdetach(ifp);
        if_detach(ifp);
        kfree(ifp, M_IFNET);
        return (0);
}

static int
lo_output(struct ifnet *ifp, struct mbuf *m, struct sockaddr *dst,
    struct rtentry *rt)
{
        M_ASSERTPKTHDR(m);

        if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
                m_freem(m);
                return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
                        rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
        }

        IFNET_STAT_INC(ifp, opackets, 1);
        IFNET_STAT_INC(ifp, obytes, m->m_pkthdr.len);
#if 1   /* XXX */
        switch (dst->sa_family) {
        case AF_INET:
        case AF_INET6:
                break;
        default:
                kprintf("lo_output: af=%d unexpected\n", dst->sa_family);
                m_freem(m);
                return (EAFNOSUPPORT);
        }
#endif

        if (ifp->if_capenable & IFCAP_RXCSUM) {
                int csum_flags = 0;

                if (m->m_pkthdr.csum_flags & CSUM_IP)
                        csum_flags |= (CSUM_IP_CHECKED | CSUM_IP_VALID);
                if (m->m_pkthdr.csum_flags & CSUM_DELAY_DATA)
                        csum_flags |= (CSUM_DATA_VALID | CSUM_PSEUDO_HDR);

                m->m_pkthdr.csum_flags |= csum_flags;
                if (csum_flags & CSUM_DATA_VALID)
                        m->m_pkthdr.csum_data = 0xffff;
        }
        if ((ifp->if_capenable & IFCAP_RSS) == 0)
                m->m_flags &= ~M_HASH;
        return (if_simloop(ifp, m, dst->sa_family, 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;

        KASSERT((m->m_flags & M_PKTHDR) != 0, ("if_simloop: no HDR"));
        m->m_pkthdr.rcvif = ifp;

        /* BPF write needs to be handled specially */
        if (af == AF_UNSPEC) {
                KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
                af = *(mtod(m, int *));
                m->m_len -= sizeof(int);
                m->m_pkthdr.len -= sizeof(int);
                m->m_data += sizeof(int);
        }

        if (ifp->if_bpf) {
                bpf_gettoken();

                /* Re-check */
                if (ifp->if_bpf == NULL)
                        goto rel;

                if (ifp->if_bpf->bif_dlt == DLT_NULL) {
                        uint32_t bpf_af = (uint32_t)af;
                        bpf_ptap(ifp->if_bpf, m, &bpf_af, 4);
                } else {
                        bpf_mtap(ifp->if_bpf, m);
                }
rel:
                bpf_reltoken();
        }

        /* Strip away media header */
        if (hlen > 0)
                m_adj(m, hlen);

#ifdef ALTQ
        /*
         * altq for loop is just for debugging.
         * only used when called for loop interface (not for
         * a simplex interface).
         */
        if (ifq_is_enabled(&ifp->if_snd) && ifp->if_start == lo_altqstart) {
                struct altq_pktattr pktattr;
                int32_t *afp;

                /*
                 * if the queueing discipline needs packet classification,
                 * do it before prepending link headers.
                 */
                ifq_classify(&ifp->if_snd, m, af, &pktattr);

                M_PREPEND(m, sizeof(int32_t), M_NOWAIT);
                if (m == NULL)
                        return(ENOBUFS);
                afp = mtod(m, int32_t *);
                *afp = (int32_t)af;

                return ifq_dispatch(ifp, m, &pktattr);
        }
#endif /* ALTQ */

        /* 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:
                kprintf("if_simloop: can't handle af=%d\n", af);
                m_freem(m);
                return (EAFNOSUPPORT);
        }

        IFNET_STAT_INC(ifp, ipackets, 1);
        IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len);
        netisr_queue(isr, m);
        return (0);
}

#ifdef ALTQ
static void
lo_altqstart(struct ifnet *ifp, struct ifaltq_subque *ifsq)
{
        struct mbuf *m;
        int32_t af, *afp;
        int isr;

        while (1) {
                crit_enter();
                m = ifsq_dequeue(ifsq);
                crit_exit();
                if (m == NULL)
                        return;

                afp = mtod(m, int32_t *);
                af = *afp;
                m_adj(m, sizeof(int32_t));

                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:
                        kprintf("lo_altqstart: can't handle af%d\n", af);
                        m_freem(m);
                        return;
                }

                IFNET_STAT_INC(ifp, ipackets, 1);
                IFNET_STAT_INC(ifp, ibytes, m->m_pkthdr.len);
                netisr_queue(isr, m);
        }
}
#endif /* ALTQ */

/* ARGSUSED */
static void
lo_rtrequest(int cmd, struct rtentry *rt)
{
        if (rt) {
                rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
                /*
                 * For optimal performance, the send and receive buffers
                 * should be at least twice the MTU plus a little more for
                 * overhead.
                 */
                rt->rt_rmx.rmx_recvpipe = rt->rt_rmx.rmx_sendpipe = 3 * LOMTU;
        }
}

/*
 * Process an ioctl request.
 */
/* ARGSUSED */
static int
lo_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data, struct ucred *cr)
{
        struct ifaddr *ifa;
        struct ifreq *ifr = (struct ifreq *)data;
        int error = 0, mask;

        switch (cmd) {
        case SIOCSIFADDR:
                ifp->if_flags |= IFF_UP | IFF_RUNNING;
                ifa = (struct ifaddr *)data;
                ifa->ifa_rtrequest = lo_rtrequest;
                /*
                 * 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:
                break;

        case SIOCSIFCAP:
                mask = ifr->ifr_reqcap ^ ifp->if_capenable;
                if (mask & IFCAP_HWCSUM) {
                        ifp->if_capenable ^= (mask & IFCAP_HWCSUM);
                        if (IFCAP_TXCSUM & ifp->if_capenable)
                                ifp->if_hwassist = LO_CSUM_FEATURES;
                        else
                                ifp->if_hwassist = 0;
                }
                if (mask & IFCAP_RSS)
                        ifp->if_capenable ^= IFCAP_RSS;
                break;

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