ng_tag.c

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/*-
 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
 *
 * Copyright (c) 2006 Vadim Goncharov <vadimnuclight@tpu.ru>
 * 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 unmodified, 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.
 *
 * Portions Copyright (c) 1999 Whistle Communications, Inc.
 * (ng_bpf by Archie Cobbs <archie@freebsd.org>)
 *
 * $FreeBSD$
 */
 
/*
 * TAG NETGRAPH NODE TYPE
 *
 * This node type accepts an arbitrary number of hooks. Each hook can be
 * configured for an mbuf_tags(9) definition and two hook names: a hook
 * for matched packets, and a hook for packets, that didn't match. Incoming
 * packets are examined for configured tag, matched packets are delivered
 * out via first hook, and not matched out via second. If corresponding hook
 * is not configured, packets are dropped.
 *
 * A hook can also have an outgoing tag definition configured, so that
 * all packets leaving the hook will be unconditionally appended with newly
 * allocated tag.
 *
 * Both hooks can be set to null tag definitions (that is, with zeroed
 * fields), so that packet tags are unmodified on output or all packets
 * are unconditionally forwarded to non-matching hook on input.  There is
 * also a possibility to replace tags by specifying strip flag on input
 * and replacing tag on corresponding output tag (or simply remove tag if
 * no tag specified on output).
 *
 * If compiled with NG_TAG_DEBUG, each hook also keeps statistics about
 * how many packets have matched, etc.
 */
 
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/errno.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/stddef.h>
 
#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_parse.h>
#include <netgraph/ng_tag.h>
 
#ifdef NG_SEPARATE_MALLOC
static MALLOC_DEFINE(M_NETGRAPH_TAG, "netgraph_tag", "netgraph tag node");
#else
#define M_NETGRAPH_TAG M_NETGRAPH
#endif
 
#define ERROUT(x)       do { error = (x); goto done; } while (0)
 
/*
 * Per hook private info.
 *
 * We've separated API and ABI here, to make easier changes in this node,
 * if needed. If you want to change representation, please do not break API.
 * We still keep API structures in memory to simplify access to them for
 * GET* messages, but most of data is accessed in internal representation
 * only.  The reason for this is to speed things up - if data will be
 * accessed from API structures, there would be double pointer dereferencing
 * in the code, which almost necessarily leads to CPU cache misses and
 * reloads.
 *
 * We also do another optimization by using resolved pointers to
 * destination hooks instead of expensive ng_findhook().
 */
struct ng_tag_hookinfo {
        hook_p                  hi_match;       /* matching hook pointer */
        hook_p                  hi_nonmatch;    /* non-matching hook pointer */
        uint32_t                in_tag_cookie;
        uint32_t                out_tag_cookie;
        uint16_t                in_tag_id;
        uint16_t                in_tag_len;
        uint16_t                out_tag_id;
        uint16_t                out_tag_len;
        uint8_t                 strip;
        void                    *in_tag_data;
        void                    *out_tag_data;
        struct ng_tag_hookin    *in;
        struct ng_tag_hookout   *out;
#ifdef NG_TAG_DEBUG
        struct ng_tag_hookstat  stats;
#endif
};
typedef struct ng_tag_hookinfo *hinfo_p;
 
/* Netgraph methods. */
static ng_constructor_t ng_tag_constructor;
static ng_rcvmsg_t      ng_tag_rcvmsg;
static ng_shutdown_t    ng_tag_shutdown;
static ng_newhook_t     ng_tag_newhook;
static ng_rcvdata_t     ng_tag_rcvdata;
static ng_disconnect_t  ng_tag_disconnect;
 
/* Internal helper functions. */
static int      ng_tag_setdata_in(hook_p hook, const struct ng_tag_hookin *hp);
static int      ng_tag_setdata_out(hook_p hook, const struct ng_tag_hookout *hp);
 
/* Parse types for the field 'tag_data' in structs ng_tag_hookin and out. */
static int
ng_tag_hookinary_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        const struct ng_tag_hookin *hp;
 
        hp = (const struct ng_tag_hookin *)
            (buf - offsetof(struct ng_tag_hookin, tag_data));
        return (hp->tag_len);
}
 
static int
ng_tag_hookoutary_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        const struct ng_tag_hookout *hp;
 
        hp = (const struct ng_tag_hookout *)
            (buf - offsetof(struct ng_tag_hookout, tag_data));
        return (hp->tag_len);
}
 
static const struct ng_parse_type ng_tag_hookinary_type = {
        &ng_parse_bytearray_type,
        &ng_tag_hookinary_getLength
};
 
static const struct ng_parse_type ng_tag_hookoutary_type = {
        &ng_parse_bytearray_type,
        &ng_tag_hookoutary_getLength
};
 
/* Parse type for struct ng_tag_hookin. */
static const struct ng_parse_struct_field ng_tag_hookin_type_fields[]
        = NG_TAG_HOOKIN_TYPE_INFO(&ng_tag_hookinary_type);
static const struct ng_parse_type ng_tag_hookin_type = {
        &ng_parse_struct_type,
        &ng_tag_hookin_type_fields
};
 
/* Parse type for struct ng_tag_hookout. */
static const struct ng_parse_struct_field ng_tag_hookout_type_fields[]
        = NG_TAG_HOOKOUT_TYPE_INFO(&ng_tag_hookoutary_type);
static const struct ng_parse_type ng_tag_hookout_type = {
        &ng_parse_struct_type,
        &ng_tag_hookout_type_fields
};
 
#ifdef NG_TAG_DEBUG
/* Parse type for struct ng_tag_hookstat. */
static const struct ng_parse_struct_field ng_tag_hookstat_type_fields[]
        = NG_TAG_HOOKSTAT_TYPE_INFO;
static const struct ng_parse_type ng_tag_hookstat_type = {
        &ng_parse_struct_type,
        &ng_tag_hookstat_type_fields
};
#endif
 
/* List of commands and how to convert arguments to/from ASCII. */
static const struct ng_cmdlist ng_tag_cmdlist[] = {
        {
          NGM_TAG_COOKIE,
          NGM_TAG_SET_HOOKIN,
          "sethookin",
          &ng_tag_hookin_type,
          NULL
        },
        {
          NGM_TAG_COOKIE,
          NGM_TAG_GET_HOOKIN,
          "gethookin",
          &ng_parse_hookbuf_type,
          &ng_tag_hookin_type
        },
        {
          NGM_TAG_COOKIE,
          NGM_TAG_SET_HOOKOUT,
          "sethookout",
          &ng_tag_hookout_type,
          NULL
        },
        {
          NGM_TAG_COOKIE,
          NGM_TAG_GET_HOOKOUT,
          "gethookout",
          &ng_parse_hookbuf_type,
          &ng_tag_hookout_type
        },
#ifdef NG_TAG_DEBUG
        {
          NGM_TAG_COOKIE,
          NGM_TAG_GET_STATS,
          "getstats",
          &ng_parse_hookbuf_type,
          &ng_tag_hookstat_type
        },
        {
          NGM_TAG_COOKIE,
          NGM_TAG_CLR_STATS,
          "clrstats",
          &ng_parse_hookbuf_type,
          NULL
        },
        {
          NGM_TAG_COOKIE,
          NGM_TAG_GETCLR_STATS,
          "getclrstats",
          &ng_parse_hookbuf_type,
          &ng_tag_hookstat_type
        },
#endif
        { 0 }
};
 
/* Netgraph type descriptor. */
static struct ng_type typestruct = {
        .version =      NG_ABI_VERSION,
        .name =         NG_TAG_NODE_TYPE,
        .constructor =  ng_tag_constructor,
        .rcvmsg =       ng_tag_rcvmsg,
        .shutdown =     ng_tag_shutdown,
        .newhook =      ng_tag_newhook,
        .rcvdata =      ng_tag_rcvdata,
        .disconnect =   ng_tag_disconnect,
        .cmdlist =      ng_tag_cmdlist,
};
NETGRAPH_INIT(tag, &typestruct);
 
/*
 * This are default API structures (initialized to zeroes) which are
 * returned in response to GET* messages when no configuration was made.
 * One could ask why to have this structures at all when we have
 * ng_tag_hookinfo initialized to zero and don't need in and out structures
 * at all to operate.  Unfortunatelly, we have to return thisHook field
 * in response to messages so the fastest and simpliest way is to have
 * this default structures and initialize thisHook once at hook creation
 * rather than to do it on every response.
 */
 
/* Default tag values for a hook that matches nothing. */
static const struct ng_tag_hookin ng_tag_default_in = {
        { '\0' },               /* to be filled in at hook creation time */
        { '\0' },
        { '\0' },
        0,
        0,
        0,
        0
};
 
/* Default tag values for a hook that adds nothing */
static const struct ng_tag_hookout ng_tag_default_out = {
        { '\0' },               /* to be filled in at hook creation time */
        0,
        0,
        0
};
 
/*
 * Node constructor.
 *
 * We don't keep any per-node private data - we do it on per-hook basis.
 */
static int
ng_tag_constructor(node_p node)
{
        return (0);
}
 
/*
 * Add a hook.
 */
static int
ng_tag_newhook(node_p node, hook_p hook, const char *name)
{
        hinfo_p hip;
        int error;
 
        /* Create hook private structure. */
        hip = malloc(sizeof(*hip), M_NETGRAPH_TAG, M_NOWAIT | M_ZERO);
        if (hip == NULL)
                return (ENOMEM);
        NG_HOOK_SET_PRIVATE(hook, hip);
 
        /*
         * After M_ZERO both in and out hook pointers are set to NULL,
         * as well as all members and pointers to in and out API
         * structures, so we need to set explicitly only thisHook field
         * in that structures (after allocating them, of course).
         */
 
        /* Attach the default IN data. */
        if ((error = ng_tag_setdata_in(hook, &ng_tag_default_in)) != 0) {
                free(hip, M_NETGRAPH_TAG);
                return (error);
        }
 
        /* Attach the default OUT data. */
        if ((error = ng_tag_setdata_out(hook, &ng_tag_default_out)) != 0) {
                free(hip, M_NETGRAPH_TAG);
                return (error);
        }
 
        /*
         * Set hook name.  This is done only once at hook creation time
         * since hook name can't change, rather than to do it on every
         * response to messages requesting API structures with data who
         * we are etc.
         */
        strncpy(hip->in->thisHook, name, sizeof(hip->in->thisHook) - 1);
        hip->in->thisHook[sizeof(hip->in->thisHook) - 1] = '\0';
        strncpy(hip->out->thisHook, name, sizeof(hip->out->thisHook) - 1);
        hip->out->thisHook[sizeof(hip->out->thisHook) - 1] = '\0';
        return (0);
}
 
/*
 * Receive a control message.
 */
static int
ng_tag_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
        struct ng_mesg *msg;
        struct ng_mesg *resp = NULL;
        int error = 0;
 
        NGI_GET_MSG(item, msg);
        switch (msg->header.typecookie) {
        case NGM_TAG_COOKIE:
                switch (msg->header.cmd) {
                case NGM_TAG_SET_HOOKIN:
                    {
                        struct ng_tag_hookin *const
                            hp = (struct ng_tag_hookin *)msg->data;
                        hook_p hook;
 
                        /* Sanity check. */
                        if (msg->header.arglen < sizeof(*hp) ||
                            msg->header.arglen < NG_TAG_HOOKIN_SIZE(hp->tag_len))
                                ERROUT(EINVAL);
 
                        /* Find hook. */
                        if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
                                ERROUT(ENOENT);
 
                        /* Set new tag values. */
                        if ((error = ng_tag_setdata_in(hook, hp)) != 0)
                                ERROUT(error);
                        break;
                    }
 
                case NGM_TAG_SET_HOOKOUT:
                    {
                        struct ng_tag_hookout *const
                            hp = (struct ng_tag_hookout *)msg->data;
                        hook_p hook;
 
                        /* Sanity check. */
                        if (msg->header.arglen < sizeof(*hp) ||
                            msg->header.arglen < NG_TAG_HOOKOUT_SIZE(hp->tag_len))
                                ERROUT(EINVAL);
 
                        /* Find hook. */
                        if ((hook = ng_findhook(node, hp->thisHook)) == NULL)
                                ERROUT(ENOENT);
 
                        /* Set new tag values. */
                        if ((error = ng_tag_setdata_out(hook, hp)) != 0)
                                ERROUT(error);
                        break;
                    }
 
                case NGM_TAG_GET_HOOKIN:
                    {
                        struct ng_tag_hookin *hp;
                        hook_p hook;
 
                        /* Sanity check. */
                        if (msg->header.arglen == 0)
                                ERROUT(EINVAL);
                        msg->data[msg->header.arglen - 1] = '\0';
 
                        /* Find hook. */
                        if ((hook = ng_findhook(node, msg->data)) == NULL)
                                ERROUT(ENOENT);
 
                        /* Build response. */
                        hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->in;
                        NG_MKRESPONSE(resp, msg,
                            NG_TAG_HOOKIN_SIZE(hp->tag_len), M_WAITOK);
                        /* M_WAITOK can't return NULL. */
                        bcopy(hp, resp->data,
                           NG_TAG_HOOKIN_SIZE(hp->tag_len));
                        break;
                    }
 
                case NGM_TAG_GET_HOOKOUT:
                    {
                        struct ng_tag_hookout *hp;
                        hook_p hook;
 
                        /* Sanity check. */
                        if (msg->header.arglen == 0)
                                ERROUT(EINVAL);
                        msg->data[msg->header.arglen - 1] = '\0';
 
                        /* Find hook. */
                        if ((hook = ng_findhook(node, msg->data)) == NULL)
                                ERROUT(ENOENT);
 
                        /* Build response. */
                        hp = ((hinfo_p)NG_HOOK_PRIVATE(hook))->out;
                        NG_MKRESPONSE(resp, msg,
                            NG_TAG_HOOKOUT_SIZE(hp->tag_len), M_WAITOK);
                        /* M_WAITOK can't return NULL. */
                        bcopy(hp, resp->data,
                           NG_TAG_HOOKOUT_SIZE(hp->tag_len));
                        break;
                    }
 
#ifdef NG_TAG_DEBUG
                case NGM_TAG_GET_STATS:
                case NGM_TAG_CLR_STATS:
                case NGM_TAG_GETCLR_STATS:
                    {
                        struct ng_tag_hookstat *stats;
                        hook_p hook;
 
                        /* Sanity check. */
                        if (msg->header.arglen == 0)
                                ERROUT(EINVAL);
                        msg->data[msg->header.arglen - 1] = '\0';
 
                        /* Find hook. */
                        if ((hook = ng_findhook(node, msg->data)) == NULL)
                                ERROUT(ENOENT);
                        stats = &((hinfo_p)NG_HOOK_PRIVATE(hook))->stats;
 
                        /* Build response (if desired). */
                        if (msg->header.cmd != NGM_TAG_CLR_STATS) {
                                NG_MKRESPONSE(resp,
                                    msg, sizeof(*stats), M_WAITOK);
                                /* M_WAITOK can't return NULL. */
                                bcopy(stats, resp->data, sizeof(*stats));
                        }
 
                        /* Clear stats (if desired). */
                        if (msg->header.cmd != NGM_TAG_GET_STATS)
                                bzero(stats, sizeof(*stats));
                        break;
                    }
#endif /* NG_TAG_DEBUG */
 
                default:
                        error = EINVAL;
                        break;
                }
                break;
        default:
                error = EINVAL;
                break;
        }
done:
        NG_RESPOND_MSG(error, node, item, resp);
        NG_FREE_MSG(msg);
        return (error);
}
 
/*
 * Receive data on a hook.
 *
 * Apply the filter, and then drop or forward packet as appropriate.
 */
static int
ng_tag_rcvdata(hook_p hook, item_p item)
{
        struct mbuf *m;
        struct m_tag *tag = NULL;
        const hinfo_p hip = NG_HOOK_PRIVATE(hook);
        uint16_t type, tag_len;
        uint32_t cookie;
        hinfo_p dhip;
        hook_p dest;
        int totlen;
        int found = 0, error = 0;
 
        m = NGI_M(item);        /* 'item' still owns it.. we are peeking */
        totlen = m->m_pkthdr.len;
 
#ifdef NG_TAG_DEBUG
        hip->stats.recvFrames++;
        hip->stats.recvOctets += totlen;
#endif
 
        /* Looking up incoming tag. */
        cookie = hip->in_tag_cookie;
        type = hip->in_tag_id;
        tag_len = hip->in_tag_len;
 
        /*
         * We treat case of all zeroes specially (that is, cookie and
         * type are equal to zero), as we assume that such tag
         * can never occur in the wild.  So we don't waste time trying
         * to find such tag (for example, these are zeroes after hook
         * creation in default structures).
         */
        if ((cookie != 0) || (type != 0)) {
                tag = m_tag_locate(m, cookie, type, NULL);
                while (tag != NULL) {
                        if (memcmp((void *)(tag + 1),
                            hip->in_tag_data, tag_len) == 0) {
                                found = 1;
                                break;
                        }
                        tag = m_tag_locate(m, cookie, type, tag);
                }
        }
 
        /* See if we got a match and find destination hook. */
        if (found) {
#ifdef NG_TAG_DEBUG
                hip->stats.recvMatchFrames++;
                hip->stats.recvMatchOctets += totlen;
#endif
                if (hip->strip)
                        m_tag_delete(m, tag);
                dest = hip->hi_match;
        } else
                dest = hip->hi_nonmatch;
        if (dest == NULL) {
                NG_FREE_ITEM(item);
                return (0);
        }
 
        /* Deliver frame out destination hook. */
        dhip = NG_HOOK_PRIVATE(dest);
 
#ifdef NG_TAG_DEBUG
        dhip->stats.xmitOctets += totlen;
        dhip->stats.xmitFrames++;
#endif
 
        cookie = dhip->out_tag_cookie;
        type = dhip->out_tag_id;
        tag_len = dhip->out_tag_len;
 
        if ((cookie != 0) || (type != 0)) {
                tag = m_tag_alloc(cookie, type, tag_len, M_NOWAIT);
                /* XXX may be free the mbuf if tag allocation failed? */
                if (tag != NULL) {
                        if (tag_len != 0) {
                                /* copy tag data to its place */
                                memcpy((void *)(tag + 1),
                                    dhip->out_tag_data, tag_len);
                        }
                        m_tag_prepend(m, tag);
                }
        }
 
        NG_FWD_ITEM_HOOK(error, item, dest);
        return (error);
}
 
/*
 * Shutdown processing.
 */
static int
ng_tag_shutdown(node_p node)
{
        NG_NODE_UNREF(node);
        return (0);
}
 
/*
 * Hook disconnection.
 *
 * We must check all hooks, since they may reference this one.
 */
static int
ng_tag_disconnect(hook_p hook)
{
        const hinfo_p hip = NG_HOOK_PRIVATE(hook);
        node_p node = NG_HOOK_NODE(hook);
        hook_p hook2;
 
        KASSERT(hip != NULL, ("%s: null info", __func__));
 
        LIST_FOREACH(hook2, &node->nd_hooks, hk_hooks) {
                hinfo_p priv = NG_HOOK_PRIVATE(hook2);
 
                if (priv->hi_match == hook)
                        priv->hi_match = NULL;
                if (priv->hi_nonmatch == hook)
                        priv->hi_nonmatch = NULL;
        }
 
        free(hip->in, M_NETGRAPH_TAG);
        free(hip->out, M_NETGRAPH_TAG);
        free(hip, M_NETGRAPH_TAG);
        NG_HOOK_SET_PRIVATE(hook, NULL);                        /* for good measure */
        if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0) &&
            (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
                ng_rmnode_self(NG_HOOK_NODE(hook));
        }
        return (0);
}
 
/************************************************************************
                        HELPER STUFF
 ************************************************************************/
 
/*
 * Set the IN tag values associated with a hook.
 */
static int
ng_tag_setdata_in(hook_p hook, const struct ng_tag_hookin *hp0)
{
        const hinfo_p hip = NG_HOOK_PRIVATE(hook);
        struct ng_tag_hookin *hp;
        int size;
 
        /* Make a copy of the tag values and data. */
        size = NG_TAG_HOOKIN_SIZE(hp0->tag_len);
        hp = malloc(size, M_NETGRAPH_TAG, M_WAITOK);
        /* M_WAITOK can't return NULL. */
        bcopy(hp0, hp, size);
 
        /* Free previous tag, if any, and assign new one. */
        if (hip->in != NULL)
                free(hip->in, M_NETGRAPH_TAG);
        hip->in = hp;
 
        /*
         * Resolve hook names to pointers.
         *
         * As ng_findhook() is expensive operation to do it on every packet
         * after tag matching check, we do it here and use resolved pointers
         * where appropriate.
         *
         * XXX The drawback is that user can configure a hook to use
         * ifMatch/ifNotMatch hooks that do not yet exist and will be added
         * by user later, so that resolved pointers will be NULL even
         * if the hook already exists, causing node to drop packets and
         * user to report bugs.  We could do check for this situation on
         * every hook creation with pointers correction, but that involves
         * re-resolving for all pointers in all hooks, up to O(n^2) operations,
         * so we better document this in man page for user not to do
         * configuration before creating all hooks.
         */
        hip->hi_match = ng_findhook(NG_HOOK_NODE(hook), hip->in->ifMatch);
        hip->hi_nonmatch = ng_findhook(NG_HOOK_NODE(hook), hip->in->ifNotMatch);
 
        /* Fill internal values from API structures. */
        hip->in_tag_cookie = hip->in->tag_cookie;
        hip->in_tag_id = hip->in->tag_id;
        hip->in_tag_len = hip->in->tag_len;
        hip->strip = hip->in->strip;
        hip->in_tag_data = (void*)(hip->in->tag_data);
        return (0);
}
 
/*
 * Set the OUT tag values associated with a hook.
 */
static int
ng_tag_setdata_out(hook_p hook, const struct ng_tag_hookout *hp0)
{
        const hinfo_p hip = NG_HOOK_PRIVATE(hook);
        struct ng_tag_hookout *hp;
        int size;
 
        /* Make a copy of the tag values and data. */
        size = NG_TAG_HOOKOUT_SIZE(hp0->tag_len);
        hp = malloc(size, M_NETGRAPH_TAG, M_WAITOK);
        /* M_WAITOK can't return NULL. */
        bcopy(hp0, hp, size);
 
        /* Free previous tag, if any, and assign new one. */
        if (hip->out != NULL)
                free(hip->out, M_NETGRAPH_TAG);
        hip->out = hp;
 
        /* Fill internal values from API structures. */
        hip->out_tag_cookie = hip->out->tag_cookie;
        hip->out_tag_id = hip->out->tag_id;
        hip->out_tag_len = hip->out->tag_len;
        hip->out_tag_data = (void*)(hip->out->tag_data);
        return (0);
}