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[dragonfly.git] / sys / netgraph7 / ng_ether.c

/*
 * ng_ether.c
 */

/*-
 * Copyright (c) 1996-2000 Whistle Communications, Inc.
 * All rights reserved.
 * 
 * Subject to the following obligations and disclaimer of warranty, use and
 * redistribution of this software, in source or object code forms, with or
 * without modifications are expressly permitted by Whistle Communications;
 * provided, however, that:
 * 1. Any and all reproductions of the source or object code must include the
 *    copyright notice above and the following disclaimer of warranties; and
 * 2. No rights are granted, in any manner or form, to use Whistle
 *    Communications, Inc. trademarks, including the mark "WHISTLE
 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
 *    such appears in the above copyright notice or in the software.
 * 
 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER 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 WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
 * OF SUCH DAMAGE.
 *
 * Authors: Archie Cobbs <archie@freebsd.org>
 *          Julian Elischer <julian@freebsd.org>
 *
 * $FreeBSD: src/sys/netgraph/ng_ether.c,v 1.62 2007/03/20 00:36:10 bms Exp $
 * $DragonFly: src/sys/netgraph7/ng_ether.c,v 1.2 2008/06/26 23:05:35 dillon Exp $
 */

/*
 * ng_ether(4) netgraph node type
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/errno.h>
#include <sys/syslog.h>
#include <sys/socket.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/if_arp.h>
#include <net/if_var.h>
#include <net/ethernet.h>
#include <net/if_bridgevar.h>

#include "ng_message.h"
#include "netgraph.h"
#include "ng_parse.h"
#include "ng_ether.h"

#define IFP2NG(ifp)  (IFP2AC((ifp))->ac_netgraph)

/* Per-node private data */
struct private {
        struct ifnet    *ifp;           /* associated interface */
        hook_p          upper;          /* upper hook connection */
        hook_p          lower;          /* lower hook connection */
        hook_p          orphan;         /* orphan hook connection */
        u_char          autoSrcAddr;    /* always overwrite source address */
        u_char          promisc;        /* promiscuous mode enabled */
        u_long          hwassist;       /* hardware checksum capabilities */
        u_int           flags;          /* flags e.g. really die */
};
typedef struct private *priv_p;

/* Hook pointers used by if_ethersubr.c to callback to netgraph */
extern  void    (*ng_ether_input_p)(struct ifnet *ifp, struct mbuf **mp);
extern  void    (*ng_ether_input_orphan_p)(struct ifnet *ifp, struct mbuf *m);
extern  int     (*ng_ether_output_p)(struct ifnet *ifp, struct mbuf **mp);
extern  void    (*ng_ether_attach_p)(struct ifnet *ifp);
extern  void    (*ng_ether_detach_p)(struct ifnet *ifp);
extern  void    (*ng_ether_link_state_p)(struct ifnet *ifp, int state);

/* Functional hooks called from if_ethersubr.c */
static void     ng_ether_input(struct ifnet *ifp, struct mbuf **mp);
static void     ng_ether_input_orphan(struct ifnet *ifp, struct mbuf *m);
static int      ng_ether_output(struct ifnet *ifp, struct mbuf **mp);
static void     ng_ether_attach(struct ifnet *ifp);
static void     ng_ether_detach(struct ifnet *ifp); 
static void     ng_ether_link_state(struct ifnet *ifp, int state); 

/* Other functions */
static int      ng_ether_rcv_lower(node_p node, struct mbuf *m);
static int      ng_ether_rcv_upper(node_p node, struct mbuf *m);

/* Netgraph node methods */
static ng_constructor_t ng_ether_constructor;
static ng_rcvmsg_t      ng_ether_rcvmsg;
static ng_shutdown_t    ng_ether_shutdown;
static ng_newhook_t     ng_ether_newhook;
static ng_rcvdata_t     ng_ether_rcvdata;
static ng_disconnect_t  ng_ether_disconnect;
static int              ng_ether_mod_event(module_t mod, int event, void *data);

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_ether_cmdlist[] = {
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_GET_IFNAME,
          "getifname",
          NULL,
          &ng_parse_string_type
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_GET_IFINDEX,
          "getifindex",
          NULL,
          &ng_parse_int32_type
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_GET_ENADDR,
          "getenaddr",
          NULL,
          &ng_parse_enaddr_type
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_SET_ENADDR,
          "setenaddr",
          &ng_parse_enaddr_type,
          NULL
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_GET_PROMISC,
          "getpromisc",
          NULL,
          &ng_parse_int32_type
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_SET_PROMISC,
          "setpromisc",
          &ng_parse_int32_type,
          NULL
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_GET_AUTOSRC,
          "getautosrc",
          NULL,
          &ng_parse_int32_type
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_SET_AUTOSRC,
          "setautosrc",
          &ng_parse_int32_type,
          NULL
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_ADD_MULTI,
          "addmulti",
          &ng_parse_enaddr_type,
          NULL
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_DEL_MULTI,
          "delmulti",
          &ng_parse_enaddr_type,
          NULL
        },
        {
          NGM_ETHER_COOKIE,
          NGM_ETHER_DETACH,
          "detach",
          NULL,
          NULL
        },
        { 0 }
};

static struct ng_type ng_ether_typestruct = {
        .version =      NG_ABI_VERSION,
        .name =         NG_ETHER_NODE_TYPE,
        .mod_event =    ng_ether_mod_event,
        .constructor =  ng_ether_constructor,
        .rcvmsg =       ng_ether_rcvmsg,
        .shutdown =     ng_ether_shutdown,
        .newhook =      ng_ether_newhook,
        .rcvdata =      ng_ether_rcvdata,
        .disconnect =   ng_ether_disconnect,
        .cmdlist =      ng_ether_cmdlist,
};
NETGRAPH_INIT(ether, &ng_ether_typestruct);

/******************************************************************
                    ETHERNET FUNCTION HOOKS
******************************************************************/

/*
 * Handle a packet that has come in on an interface. We get to
 * look at it here before any upper layer protocols do.
 *
 * NOTE: this function will get called at splimp()
 */
static void
ng_ether_input(struct ifnet *ifp, struct mbuf **mp)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);
        int error;

        /* If "lower" hook not connected, let packet continue */
        if (priv->lower == NULL)
                return;
        NG_SEND_DATA_ONLY(error, priv->lower, *mp);     /* sets *mp = NULL */
}

/*
 * Handle a packet that has come in on an interface, and which
 * does not match any of our known protocols (an ``orphan'').
 *
 * NOTE: this function will get called at splimp()
 */
static void
ng_ether_input_orphan(struct ifnet *ifp, struct mbuf *m)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);
        int error;

        /* If "orphan" hook not connected, discard packet */
        if (priv->orphan == NULL) {
                m_freem(m);
                return;
        }
        NG_SEND_DATA_ONLY(error, priv->orphan, m);
}

/*
 * Handle a packet that is going out on an interface.
 * The Ethernet header is already attached to the mbuf.
 */
static int
ng_ether_output(struct ifnet *ifp, struct mbuf **mp)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);
        int error = 0;

        /* If "upper" hook not connected, let packet continue */
        if (priv->upper == NULL)
                return (0);

        /* Send it out "upper" hook */
        NG_SEND_DATA_ONLY(error, priv->upper, *mp);
        return (error);
}

/*
 * A new Ethernet interface has been attached.
 * Create a new node for it, etc.
 */
static void
ng_ether_attach(struct ifnet *ifp)
{
        priv_p priv;
        node_p node;

        /* Create node */
        KASSERT(!IFP2NG(ifp), ("%s: node already exists?", __func__));
        if (ng_make_node_common(&ng_ether_typestruct, &node) != 0) {
                log(LOG_ERR, "%s: can't %s for %s\n",
                    __func__, "create node", ifp->if_xname);
                return;
        }

        /* Allocate private data */
        MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_WAITOK | M_NULLOK | M_ZERO);
        if (priv == NULL) {
                log(LOG_ERR, "%s: can't %s for %s\n",
                    __func__, "allocate memory", ifp->if_xname);
                NG_NODE_UNREF(node);
                return;
        }
        NG_NODE_SET_PRIVATE(node, priv);
        priv->ifp = ifp;
        IFP2NG(ifp) = node;
        priv->hwassist = ifp->if_hwassist;

        /* Try to give the node the same name as the interface */
        if (ng_name_node(node, ifp->if_xname) != 0) {
                log(LOG_WARNING, "%s: can't name node %s\n",
                    __func__, ifp->if_xname);
        }
}

/*
 * An Ethernet interface is being detached.
 * REALLY Destroy its node.
 */
static void
ng_ether_detach(struct ifnet *ifp)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);

        NG_NODE_REALLY_DIE(node);       /* Force real removal of node */
        /*
         * We can't assume the ifnet is still around when we run shutdown
         * So zap it now. XXX We HOPE that anything running at this time
         * handles it (as it should in the non netgraph case).
         */
        IFP2NG(ifp) = NULL;
        priv->ifp = NULL;       /* XXX race if interrupted an output packet */
        ng_rmnode_self(node);           /* remove all netgraph parts */
}

/*
 * Notify graph about link event.
 * if_link_state_change() has already checked that the state has changed.
 */
static void
ng_ether_link_state(struct ifnet *ifp, int state)
{
        const node_p node = IFP2NG(ifp);
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ng_mesg *msg;
        int cmd, dummy_error = 0;

        if (priv->lower == NULL)
                return;

        if (state == LINK_STATE_UP)
                cmd = NGM_LINK_IS_UP;
        else if (state == LINK_STATE_DOWN)
                cmd = NGM_LINK_IS_DOWN;
        else
                return;

        NG_MKMESSAGE(msg, NGM_FLOW_COOKIE, cmd, 0, M_WAITOK | M_NULLOK);
        if (msg != NULL)
                NG_SEND_MSG_HOOK(dummy_error, node, msg, priv->lower, 0);
}

/******************************************************************
                    NETGRAPH NODE METHODS
******************************************************************/

/*
 * It is not possible or allowable to create a node of this type.
 * Nodes get created when the interface is attached (or, when
 * this node type's KLD is loaded).
 */
static int
ng_ether_constructor(node_p node)
{
        return (EINVAL);
}

/*
 * Check for attaching a new hook.
 */
static  int
ng_ether_newhook(node_p node, hook_p hook, const char *name)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        hook_p *hookptr;

        /* Divert hook is an alias for lower */
        if (strcmp(name, NG_ETHER_HOOK_DIVERT) == 0)
                name = NG_ETHER_HOOK_LOWER;

        /* Which hook? */
        if (strcmp(name, NG_ETHER_HOOK_UPPER) == 0)
                hookptr = &priv->upper;
        else if (strcmp(name, NG_ETHER_HOOK_LOWER) == 0)
                hookptr = &priv->lower;
        else if (strcmp(name, NG_ETHER_HOOK_ORPHAN) == 0)
                hookptr = &priv->orphan;
        else
                return (EINVAL);

        /* Check if already connected (shouldn't be, but doesn't hurt) */
        if (*hookptr != NULL)
                return (EISCONN);

        /* Disable hardware checksums while 'upper' hook is connected */
        if (hookptr == &priv->upper)
                priv->ifp->if_hwassist = 0;

        /* OK */
        *hookptr = hook;
        return (0);
}

/*
 * Receive an incoming control message.
 */
static int
ng_ether_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ng_mesg *resp = NULL;
        int error = 0;
        struct ng_mesg *msg;

        NGI_GET_MSG(item, msg);
        switch (msg->header.typecookie) {
        case NGM_ETHER_COOKIE:
                switch (msg->header.cmd) {
                case NGM_ETHER_GET_IFNAME:
                        NG_MKRESPONSE(resp, msg, IFNAMSIZ, M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        strlcpy(resp->data, priv->ifp->if_xname, IFNAMSIZ);
                        break;
                case NGM_ETHER_GET_IFINDEX:
                        NG_MKRESPONSE(resp, msg, sizeof(u_int32_t), M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        *((u_int32_t *)resp->data) = priv->ifp->if_index;
                        break;
                case NGM_ETHER_GET_ENADDR:
                        NG_MKRESPONSE(resp, msg, ETHER_ADDR_LEN, M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        bcopy(IF_LLADDR(priv->ifp),
                            resp->data, ETHER_ADDR_LEN);
                        break;
                case NGM_ETHER_SET_ENADDR:
                    {
                        if (msg->header.arglen != ETHER_ADDR_LEN) {
                                error = EINVAL;
                                break;
                        }
                        error = if_setlladdr(priv->ifp,
                            (u_char *)msg->data, ETHER_ADDR_LEN);
                        break;
                    }
                case NGM_ETHER_GET_PROMISC:
                        NG_MKRESPONSE(resp, msg, sizeof(u_int32_t), M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        *((u_int32_t *)resp->data) = priv->promisc;
                        break;
                case NGM_ETHER_SET_PROMISC:
                    {
                        u_char want;

                        if (msg->header.arglen != sizeof(u_int32_t)) {
                                error = EINVAL;
                                break;
                        }
                        want = !!*((u_int32_t *)msg->data);
                        if (want ^ priv->promisc) {
                                if ((error = ifpromisc(priv->ifp, want)) != 0)
                                        break;
                                priv->promisc = want;
                        }
                        break;
                    }
                case NGM_ETHER_GET_AUTOSRC:
                        NG_MKRESPONSE(resp, msg, sizeof(u_int32_t), M_WAITOK | M_NULLOK);
                        if (resp == NULL) {
                                error = ENOMEM;
                                break;
                        }
                        *((u_int32_t *)resp->data) = priv->autoSrcAddr;
                        break;
                case NGM_ETHER_SET_AUTOSRC:
                        if (msg->header.arglen != sizeof(u_int32_t)) {
                                error = EINVAL;
                                break;
                        }
                        priv->autoSrcAddr = !!*((u_int32_t *)msg->data);
                        break;
                case NGM_ETHER_ADD_MULTI:
                    {
                        struct sockaddr_dl sa_dl;
                        struct ifmultiaddr *ifma;

                        if (msg->header.arglen != ETHER_ADDR_LEN) {
                                error = EINVAL;
                                break;
                        }
                        bzero(&sa_dl, sizeof(struct sockaddr_dl));
                        sa_dl.sdl_len = sizeof(struct sockaddr_dl);
                        sa_dl.sdl_family = AF_LINK;
                        sa_dl.sdl_alen = ETHER_ADDR_LEN;
                        bcopy((void *)msg->data, LLADDR(&sa_dl),
                            ETHER_ADDR_LEN);
                        /*
                         * Netgraph is only permitted to join groups once
                         * via the if_addmulti() KPI, because it cannot hold
                         * struct ifmultiaddr * between calls. It may also
                         * lose a race while we check if the membership
                         * already exists.
                         */
                        IF_ADDR_LOCK(priv->ifp);
                        ifma = if_findmulti(priv->ifp,
                            (struct sockaddr *)&sa_dl);
                        IF_ADDR_UNLOCK(priv->ifp);
                        if (ifma != NULL) {
                                error = EADDRINUSE;
                        } else {
                                error = if_addmulti(priv->ifp,
                                    (struct sockaddr *)&sa_dl, &ifma);
                        }
                        break;
                    }
                case NGM_ETHER_DEL_MULTI:
                    {
                        struct sockaddr_dl sa_dl;

                        if (msg->header.arglen != ETHER_ADDR_LEN) {
                                error = EINVAL;
                                break;
                        }
                        bzero(&sa_dl, sizeof(struct sockaddr_dl));
                        sa_dl.sdl_len = sizeof(struct sockaddr_dl);
                        sa_dl.sdl_family = AF_LINK;
                        sa_dl.sdl_alen = ETHER_ADDR_LEN;
                        bcopy((void *)msg->data, LLADDR(&sa_dl),
                            ETHER_ADDR_LEN);
                        error = if_delmulti(priv->ifp,
                            (struct sockaddr *)&sa_dl);
                        break;
                    }
                case NGM_ETHER_DETACH:
                        ng_ether_detach(priv->ifp);
                        break;
                default:
                        error = EINVAL;
                        break;
                }
                break;
        default:
                error = EINVAL;
                break;
        }
        NG_RESPOND_MSG(error, node, item, resp);
        NG_FREE_MSG(msg);
        return (error);
}

/*
 * Receive data on a hook.
 */
static int
ng_ether_rcvdata(hook_p hook, item_p item)
{
        const node_p node = NG_HOOK_NODE(hook);
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct mbuf *m;

        NGI_GET_M(item, m);
        NG_FREE_ITEM(item);

        if (hook == priv->lower || hook == priv->orphan)
                return ng_ether_rcv_lower(node, m);
        if (hook == priv->upper)
                return ng_ether_rcv_upper(node, m);
        panic("%s: weird hook", __func__);
#ifdef RESTARTABLE_PANICS /* so we don't get an error msg in LINT */
        return (0);
#endif
}

/*
 * Handle an mbuf received on the "lower" or "orphan" hook.
 */
static int
ng_ether_rcv_lower(node_p node, struct mbuf *m)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ifnet *const ifp = priv->ifp;

        /* Check whether interface is ready for packets */
        if (!((ifp->if_flags & IFF_UP) &&
            (ifp->if_drv_flags & IFF_DRV_RUNNING))) {
                NG_FREE_M(m);
                return (ENETDOWN);
        }

        /* Make sure header is fully pulled up */
        if (m->m_pkthdr.len < sizeof(struct ether_header)) {
                NG_FREE_M(m);
                return (EINVAL);
        }
        if (m->m_len < sizeof(struct ether_header)
            && (m = m_pullup(m, sizeof(struct ether_header))) == NULL)
                return (ENOBUFS);

        /* Drop in the MAC address if desired */
        if (priv->autoSrcAddr) {

                /* Make the mbuf writable if it's not already */
                if (!M_WRITABLE(m)
                    && (m = m_pullup(m, sizeof(struct ether_header))) == NULL)
                        return (ENOBUFS);

                /* Overwrite source MAC address */
                bcopy(IF_LLADDR(ifp),
                    mtod(m, struct ether_header *)->ether_shost,
                    ETHER_ADDR_LEN);
        }

        /* Send it on its way */
        return ether_output_frame(ifp, m);
}

/*
 * Handle an mbuf received on the "upper" hook.
 */
static int
ng_ether_rcv_upper(node_p node, struct mbuf *m)
{
        const priv_p priv = NG_NODE_PRIVATE(node);
        struct ifnet *ifp = priv->ifp;

        /* Check length and pull off header */
        if (m->m_pkthdr.len < sizeof(struct ether_header)) {
                NG_FREE_M(m);
                return (EINVAL);
        }
        if (m->m_len < sizeof(struct ether_header) &&
            (m = m_pullup(m, sizeof(struct ether_header))) == NULL)
                return (ENOBUFS);

        m->m_pkthdr.rcvif = ifp;

        /* Pass the packet to the bridge, it may come back to us */
        if (ifp->if_bridge) {
                BRIDGE_INPUT(ifp, m);
                if (m == NULL)
                        return (0);
        }

        /* Route packet back in */
        ether_demux(ifp, m);
        return (0);
}

/*
 * Shutdown node. This resets the node but does not remove it
 * unless the REALLY_DIE flag is set.
 */
static int
ng_ether_shutdown(node_p node)
{
        const priv_p priv = NG_NODE_PRIVATE(node);

        if (node->nd_flags & NGF_REALLY_DIE) {
                /*
                 * WE came here because the ethernet card is being unloaded,
                 * so stop being persistant.
                 * Actually undo all the things we did on creation.
                 * Assume the ifp has already been freed.
                 */
                NG_NODE_SET_PRIVATE(node, NULL);
                FREE(priv, M_NETGRAPH);         
                NG_NODE_UNREF(node);    /* free node itself */
                return (0);
        }
        if (priv->promisc) {            /* disable promiscuous mode */
                (void)ifpromisc(priv->ifp, 0);
                priv->promisc = 0;
        }
        priv->autoSrcAddr = 1;          /* reset auto-src-addr flag */
        NG_NODE_REVIVE(node);           /* Signal ng_rmnode we are persisant */

        return (0);
}

/*
 * Hook disconnection.
 */
static int
ng_ether_disconnect(hook_p hook)
{
        const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));

        if (hook == priv->upper) {
                priv->upper = NULL;
                if (priv->ifp != NULL)          /* restore h/w csum */
                        priv->ifp->if_hwassist = priv->hwassist;
        } else if (hook == priv->lower)
                priv->lower = NULL;
        else if (hook == priv->orphan)
                priv->orphan = NULL;
        else
                panic("%s: weird hook", __func__);
        if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
        && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook))))
                ng_rmnode_self(NG_HOOK_NODE(hook));     /* reset node */
        return (0);
}

/******************************************************************
                        INITIALIZATION
******************************************************************/

/*
 * Handle loading and unloading for this node type.
 */
static int
ng_ether_mod_event(module_t mod, int event, void *data)
{
        struct ifnet *ifp;
        int error = 0;
        int s;

        s = splnet();
        switch (event) {
        case MOD_LOAD:

                /* Register function hooks */
                if (ng_ether_attach_p != NULL) {
                        error = EEXIST;
                        break;
                }
                ng_ether_attach_p = ng_ether_attach;
                ng_ether_detach_p = ng_ether_detach;
                ng_ether_output_p = ng_ether_output;
                ng_ether_input_p = ng_ether_input;
                ng_ether_input_orphan_p = ng_ether_input_orphan;
                ng_ether_link_state_p = ng_ether_link_state;

                /* Create nodes for any already-existing Ethernet interfaces */
                IFNET_RLOCK();
                TAILQ_FOREACH(ifp, &ifnet, if_link) {
                        if (ifp->if_type == IFT_ETHER
                            || ifp->if_type == IFT_L2VLAN)
                                ng_ether_attach(ifp);
                }
                IFNET_RUNLOCK();
                break;

        case MOD_UNLOAD:

                /*
                 * Note that the base code won't try to unload us until
                 * all nodes have been removed, and that can't happen
                 * until all Ethernet interfaces are removed. In any
                 * case, we know there are no nodes left if the action
                 * is MOD_UNLOAD, so there's no need to detach any nodes.
                 */

                /* Unregister function hooks */
                ng_ether_attach_p = NULL;
                ng_ether_detach_p = NULL;
                ng_ether_output_p = NULL;
                ng_ether_input_p = NULL;
                ng_ether_input_orphan_p = NULL;
                ng_ether_link_state_p = NULL;
                break;

        default:
                error = EOPNOTSUPP;
                break;
        }
        splx(s);
        return (error);
}