/*-
 * Copyright (c) 1996-1999 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: Julian Elischer <julian@freebsd.org>
 *          Archie Cobbs <archie@freebsd.org>
 *
 * $FreeBSD: src/sys/netgraph/ng_base.c,v 1.159 2008/04/19 05:30:49 mav Exp $
 * $Whistle: ng_base.c,v 1.39 1999/01/28 23:54:53 julian Exp $
 */

/*
 * This file implements the base netgraph code.
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/ctype.h>
#include <sys/errno.h>
#include <sys/hash.h>
/*#include <sys/kdb.h>*/
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/msgport2.h>
#include <sys/mutex2.h>
#include <sys/objcache.h>
#include <sys/proc.h>
#include <sys/queue.h>
#include <sys/refcount.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <machine/cpu.h>

#include <netgraph7/netgraph.h>
#include <netgraph7/netgraph2.h>
#include <netgraph7/ng_parse.h>

MODULE_VERSION(netgraph, NG_ABI_VERSION);

/* Token to protect topology events. */
static struct lwkt_token        ng_topo_token;
#define TOPOLOGY_RLOCK()        lwkt_gettoken_shared(&ng_topo_token)
#define TOPOLOGY_RUNLOCK()      lwkt_reltoken(&ng_topo_token)
#define TOPOLOGY_WLOCK()        lwkt_gettoken(&ng_topo_token)
#define TOPOLOGY_WUNLOCK()      lwkt_reltoken(&ng_topo_token)
#define TOPOLOGY_NOTOWNED()     KKASSERT(!LWKT_TOKEN_HELD_ANY(&ng_topo_token))

#ifdef  NETGRAPH_DEBUG
static struct mtx       ng_nodelist_mtx; /* protects global node/hook lists */
static struct mtx       ngq_mtx;        /* protects the queue item list */

static SLIST_HEAD(, ng_node) ng_allnodes;
static LIST_HEAD(, ng_node) ng_freenodes; /* in debug, we never free() them */
static SLIST_HEAD(, ng_hook) ng_allhooks;
static LIST_HEAD(, ng_hook) ng_freehooks; /* in debug, we never free() them */

static void ng_dumpitems(void);
static void ng_dumpnodes(void);
static void ng_dumphooks(void);

#endif  /* NETGRAPH_DEBUG */
/*
 * DEAD versions of the structures.
 * In order to avoid races, it is sometimes necessary to point
 * at SOMETHING even though theoretically, the current entity is
 * INVALID. Use these to avoid these races.
 */
struct ng_type ng_deadtype = {
        NG_ABI_VERSION,
        "dead",
        NULL,   /* modevent */
        NULL,   /* constructor */
        NULL,   /* rcvmsg */
        NULL,   /* shutdown */
        NULL,   /* newhook */
        NULL,   /* findhook */
        NULL,   /* connect */
        NULL,   /* rcvdata */
        NULL,   /* disconnect */
        NULL,   /* cmdlist */
};

struct ng_node ng_deadnode = {
        "dead",
        &ng_deadtype,   
        NGF_INVALID,
        0,      /* numhooks */
        NULL,   /* private */
        0,      /* ID */
        LIST_HEAD_INITIALIZER(ng_deadnode.hooks),
        {},     /* all_nodes list entry */
        {},     /* id hashtable list entry */
        {
                0,
                NULL,
                0,
                NULL,
        },      /* token */
        1,      /* refs */
#ifdef  NETGRAPH_DEBUG
        ND_MAGIC,
        __FILE__,
        __LINE__,
        {NULL}
#endif  /* NETGRAPH_DEBUG */
};

struct ng_hook ng_deadhook = {
        "dead",
        NULL,           /* private */
        HK_INVALID | HK_DEAD,
        0,              /* undefined data link type */
        &ng_deadhook,   /* Peer is self */
        &ng_deadnode,   /* attached to deadnode */
        {},             /* hooks list */
        NULL,           /* override rcvmsg() */
        NULL,           /* override rcvdata() */
        1,              /* refs always >= 1 */
#ifdef  NETGRAPH_DEBUG
        HK_MAGIC,
        __FILE__,
        __LINE__,
        {NULL}
#endif  /* NETGRAPH_DEBUG */
};

/*
 * END DEAD STRUCTURES
 */

/* We don't want our messages to be replied. This is our panic reply port. */
static struct lwkt_port ng_panic_reply_port;

/* Array of per-CPU target ports */
struct lwkt_port *ng_msgport[MAXCPU];

/* List of installed types */
static LIST_HEAD(, ng_type) ng_typelist;
static struct lwkt_token        ng_typelist_token;
#define TYPELIST_RLOCK()        lwkt_gettoken_shared(&ng_typelist_token)
#define TYPELIST_RUNLOCK()      lwkt_reltoken(&ng_typelist_token)
#define TYPELIST_WLOCK()        lwkt_gettoken(&ng_typelist_token)
#define TYPELIST_WUNLOCK()      lwkt_reltoken(&ng_typelist_token)

/* Hash related definitions */
LIST_HEAD(nodehash, ng_node);
static struct nodehash          *ng_ID_hash;
static u_long                    ng_ID_hmask;
static u_long                    ng_nodes;
static struct nodehash          *ng_name_hash;
static u_long                    ng_name_hmask;
static u_long                    ng_named_nodes;
static struct lwkt_token         ng_idhash_token;
#define IDHASH_RLOCK()          lwkt_gettoken_shared(&ng_idhash_token)
#define IDHASH_RUNLOCK()        lwkt_reltoken(&ng_idhash_token)
#define IDHASH_WLOCK()          lwkt_gettoken(&ng_idhash_token)
#define IDHASH_WUNLOCK()        lwkt_reltoken(&ng_idhash_token)
#define IDHASH_ASSERT_LOCKED()  KKASSERT(LWKT_TOKEN_HELD_ANY(&ng_idhash_token));
/* Method to find a node.. used twice so do it here */
#define NG_IDHASH_FN(ID) ((ID) % (ng_ID_hmask + 1))
#define NG_IDHASH_FIND(ID, node)                                        \
        do {                                                            \
                IDHASH_ASSERT_LOCKED();                                 \
                LIST_FOREACH(node, &ng_ID_hash[NG_IDHASH_FN(ID)],       \
                                                nd_idnodes) {           \
                        if (NG_NODE_IS_VALID(node)                      \
                        && (NG_NODE_ID(node) == ID)) {                  \
                                break;                                  \
                        }                                               \
                }                                                       \
        } while (0)

static struct lwkt_token                ng_namehash_token;
#define NAMEHASH_RLOCK()                lwkt_gettoken_shared(&ng_namehash_token)
#define NAMEHASH_RUNLOCK()              lwkt_reltoken(&ng_namehash_token)
#define NAMEHASH_WLOCK()                lwkt_gettoken(&ng_namehash_token)
#define NAMEHASH_WUNLOCK()              lwkt_reltoken(&ng_namehash_token)
#define NAMEHASH_ASSERT_LOCKED()        KKASSERT(LWKT_TOKEN_HELD_ANY(&ng_namehash_token));

/* Internal functions */
static int      ng_add_hook(node_p node, const char *name, hook_p * hookp);
static int      ng_generic_msg(node_p here, item_p item, hook_p lasthook);
static ng_ID_t  ng_decodeidname(const char *name);
static int      ngb_mod_event(module_t mod, int event, void *data);
static void     ngthread(void *dummy);
static int      ng_apply_item(item_p item);
static node_p   ng_ID2noderef(ng_ID_t ID);
static int      ng_con_nodes(item_p item, node_p node, const char *name,
                    node_p node2, const char *name2);
static int      ng_con_part2(node_p node, item_p item, hook_p hook);
static int      ng_con_part3(node_p node, item_p item, hook_p hook);
static int      ng_mkpeer(node_p node, const char *name, const char *name2,
                    char *type);
static void     ng_name_rehash(void);
static void     ng_ID_rehash(void);
static boolean_t        bzero_ctor(void *obj, void *private, int ocflags);

/* Imported, these used to be externally visible, some may go back. */
void    ng_destroy_hook(hook_p hook);
node_p  ng_name2noderef(node_p node, const char *name);
int     ng_path2noderef(node_p here, const char *path,
        node_p *dest, hook_p *lasthook);
int     ng_make_node(const char *type, node_p *nodepp);
int     ng_path_parse(char *addr, char **node, char **path, char **hook);
void    ng_rmnode(node_p node, hook_p dummy1, void *dummy2, int dummy3);
void    ng_unname(node_p node);


/* Our own netgraph malloc type */
MALLOC_DEFINE(M_NETGRAPH, "netgraph", "netgraph structures and ctrl messages");
MALLOC_DEFINE(M_NETGRAPH_HOOK, "netgraph_hook", "netgraph hook structures");
MALLOC_DEFINE(M_NETGRAPH_NODE, "netgraph_node", "netgraph node structures");
MALLOC_DEFINE(M_NETGRAPH_MSG, "netgraph_msg", "netgraph name storage");
MALLOC_DEFINE(M_NETGRAPH_APPLY, "netgraph_apply", "netgraph apply_info structures");

/* Should not be visible outside this file */

#define _NG_ALLOC_HOOK(hook) \
        hook = kmalloc(sizeof(*hook), M_NETGRAPH_HOOK, \
            M_WAITOK | M_NULLOK | M_ZERO)
#define _NG_ALLOC_NODE(node) \
        node = kmalloc(sizeof(*node), M_NETGRAPH_NODE, \
            M_WAITOK | M_NULLOK | M_ZERO)

#ifdef NETGRAPH_DEBUG /*----------------------------------------------*/
/*
 * In debug mode:
 * In an attempt to help track reference count screwups
 * we do not free objects back to the malloc system, but keep them
 * in a local cache where we can examine them and keep information safely
 * after they have been freed.
 * We use this scheme for nodes and hooks, and to some extent for items.
 */
static __inline hook_p
ng_alloc_hook(void)
{
        hook_p hook;
        SLIST_ENTRY(ng_hook) temp;
        mtx_lock(&ng_nodelist_mtx);
        hook = LIST_FIRST(&ng_freehooks);
        if (hook) {
                LIST_REMOVE(hook, hk_hooks);
                bcopy(&hook->hk_all, &temp, sizeof(temp));
                bzero(hook, sizeof(struct ng_hook));
                bcopy(&temp, &hook->hk_all, sizeof(temp));
                mtx_unlock(&ng_nodelist_mtx);
                hook->hk_magic = HK_MAGIC;
        } else {
                mtx_unlock(&ng_nodelist_mtx);
                _NG_ALLOC_HOOK(hook);
                if (hook) {
                        hook->hk_magic = HK_MAGIC;
                        mtx_lock(&ng_nodelist_mtx);
                        SLIST_INSERT_HEAD(&ng_allhooks, hook, hk_all);
                        mtx_unlock(&ng_nodelist_mtx);
                }
        }
        return (hook);
}

static __inline node_p
ng_alloc_node(void)
{
        node_p node;
        SLIST_ENTRY(ng_node) temp;
        mtx_lock(&ng_nodelist_mtx);
        node = LIST_FIRST(&ng_freenodes);
        if (node) {
                LIST_REMOVE(node, nd_nodes);
                bcopy(&node->nd_all, &temp, sizeof(temp));
                bzero(node, sizeof(struct ng_node));
                bcopy(&temp, &node->nd_all, sizeof(temp));
                mtx_unlock(&ng_nodelist_mtx);
                node->nd_magic = ND_MAGIC;
        } else {
                mtx_unlock(&ng_nodelist_mtx);
                _NG_ALLOC_NODE(node);
                if (node) {
                        node->nd_magic = ND_MAGIC;
                        mtx_lock(&ng_nodelist_mtx);
                        SLIST_INSERT_HEAD(&ng_allnodes, node, nd_all);
                        mtx_unlock(&ng_nodelist_mtx);
                }
        }
        return (node);
}

#define NG_ALLOC_HOOK(hook) do { (hook) = ng_alloc_hook(); } while (0)
#define NG_ALLOC_NODE(node) do { (node) = ng_alloc_node(); } while (0)


#define NG_FREE_HOOK(hook)                                              \
        do {                                                            \
                mtx_lock(&ng_nodelist_mtx);                     \
                LIST_INSERT_HEAD(&ng_freehooks, hook, hk_hooks);        \
                hook->hk_magic = 0;                                     \
                mtx_unlock(&ng_nodelist_mtx);                   \
        } while (0)

#define NG_FREE_NODE(node)                                              \
        do {                                                            \
                mtx_lock(&ng_nodelist_mtx);                     \
                LIST_INSERT_HEAD(&ng_freenodes, node, nd_nodes);        \
                node->nd_magic = 0;                                     \
                mtx_unlock(&ng_nodelist_mtx);                   \
        } while (0)

#else /* NETGRAPH_DEBUG */ /*----------------------------------------------*/

#define NG_ALLOC_HOOK(hook) _NG_ALLOC_HOOK(hook)
#define NG_ALLOC_NODE(node) _NG_ALLOC_NODE(node)

#define NG_FREE_HOOK(hook) do { kfree((hook), M_NETGRAPH_HOOK); } while (0)
#define NG_FREE_NODE(node) do { kfree((node), M_NETGRAPH_NODE); } while (0)

#endif /* NETGRAPH_DEBUG */ /*----------------------------------------------*/

/* Set this to kdb_enter("X") to catch all errors as they occur */
#ifndef TRAP_ERROR
#define TRAP_ERROR()
#endif

static  ng_ID_t nextID = 1;

#ifdef INVARIANTS
#define CHECK_DATA_MBUF(m)      do {                                    \
                struct mbuf *n;                                         \
                int total;                                              \
                                                                        \
                M_ASSERTPKTHDR(m);                                      \
                for (total = 0, n = (m); n != NULL; n = n->m_next) {    \
                        total += n->m_len;                              \
                        if (n->m_nextpkt != NULL)                       \
                                panic("%s: m_nextpkt", __func__);       \
                }                                                       \
                                                                        \
                if ((m)->m_pkthdr.len != total) {                       \
                        panic("%s: %d != %d",                           \
                            __func__, (m)->m_pkthdr.len, total);        \
                }                                                       \
        } while (0)
#else
#define CHECK_DATA_MBUF(m)
#endif

#define ERROUT(x)       do { error = (x); goto done; } while (0)

/************************************************************************
        Parse type definitions for generic messages
************************************************************************/

/* Handy structure parse type defining macro */
#define DEFINE_PARSE_STRUCT_TYPE(lo, up, args)                          \
static const struct ng_parse_struct_field                               \
        ng_ ## lo ## _type_fields[] = NG_GENERIC_ ## up ## _INFO args;  \
static const struct ng_parse_type ng_generic_ ## lo ## _type = {        \
        &ng_parse_struct_type,                                          \
        &ng_ ## lo ## _type_fields                                      \
}

DEFINE_PARSE_STRUCT_TYPE(mkpeer, MKPEER, ());
DEFINE_PARSE_STRUCT_TYPE(connect, CONNECT, ());
DEFINE_PARSE_STRUCT_TYPE(name, NAME, ());
DEFINE_PARSE_STRUCT_TYPE(rmhook, RMHOOK, ());
DEFINE_PARSE_STRUCT_TYPE(nodeinfo, NODEINFO, ());
DEFINE_PARSE_STRUCT_TYPE(typeinfo, TYPEINFO, ());
DEFINE_PARSE_STRUCT_TYPE(linkinfo, LINKINFO, (&ng_generic_nodeinfo_type));

/* Get length of an array when the length is stored as a 32 bit
   value immediately preceding the array -- as with struct namelist
   and struct typelist. */
static int
ng_generic_list_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        return *((const u_int32_t *)(buf - 4));
}

/* Get length of the array of struct linkinfo inside a struct hooklist */
static int
ng_generic_linkinfo_getLength(const struct ng_parse_type *type,
        const u_char *start, const u_char *buf)
{
        const struct hooklist *hl = (const struct hooklist *)start;

        return hl->nodeinfo.hooks;
}

/* Array type for a variable length array of struct namelist */
static const struct ng_parse_array_info ng_nodeinfoarray_type_info = {
        &ng_generic_nodeinfo_type,
        &ng_generic_list_getLength
};
static const struct ng_parse_type ng_generic_nodeinfoarray_type = {
        &ng_parse_array_type,
        &ng_nodeinfoarray_type_info
};

#if 0 /* unused */
/* Array type for a variable length array of struct typelist */
static const struct ng_parse_array_info ng_typeinfoarray_type_info = {
        &ng_generic_typeinfo_type,
        &ng_generic_list_getLength
};
static const struct ng_parse_type ng_generic_typeinfoarray_type = {
        &ng_parse_array_type,
        &ng_typeinfoarray_type_info
};
#endif

/* Array type for array of struct linkinfo in struct hooklist */
static const struct ng_parse_array_info ng_generic_linkinfo_array_type_info = {
        &ng_generic_linkinfo_type,
        &ng_generic_linkinfo_getLength
};
static const struct ng_parse_type ng_generic_linkinfo_array_type = {
        &ng_parse_array_type,
        &ng_generic_linkinfo_array_type_info
};

#if 0 /* unused */
DEFINE_PARSE_STRUCT_TYPE(typelist, TYPELIST, (&ng_generic_typeinfoarray_type));
#endif
DEFINE_PARSE_STRUCT_TYPE(hooklist, HOOKLIST,
        (&ng_generic_nodeinfo_type, &ng_generic_linkinfo_array_type));
DEFINE_PARSE_STRUCT_TYPE(listnodes, LISTNODES,
        (&ng_generic_nodeinfoarray_type));

/* List of commands and how to convert arguments to/from ASCII */
static const struct ng_cmdlist ng_generic_cmds[] = {
        {
          NGM_GENERIC_COOKIE,
          NGM_SHUTDOWN,
          "shutdown",
          NULL,
          NULL
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_MKPEER,
          "mkpeer",
          &ng_generic_mkpeer_type,
          NULL
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_CONNECT,
          "connect",
          &ng_generic_connect_type,
          NULL
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_NAME,
          "name",
          &ng_generic_name_type,
          NULL
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_RMHOOK,
          "rmhook",
          &ng_generic_rmhook_type,
          NULL
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_NODEINFO,
          "nodeinfo",
          NULL,
          &ng_generic_nodeinfo_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_LISTHOOKS,
          "listhooks",
          NULL,
          &ng_generic_hooklist_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_LISTNAMES,
          "listnames",
          NULL,
          &ng_generic_listnodes_type    /* same as NGM_LISTNODES */
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_LISTNODES,
          "listnodes",
          NULL,
          &ng_generic_listnodes_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_LISTTYPES,
          "listtypes",
          NULL,
          &ng_generic_typeinfo_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_TEXT_CONFIG,
          "textconfig",
          NULL,
          &ng_parse_string_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_TEXT_STATUS,
          "textstatus",
          NULL,
          &ng_parse_string_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_ASCII2BINARY,
          "ascii2binary",
          &ng_parse_ng_mesg_type,
          &ng_parse_ng_mesg_type
        },
        {
          NGM_GENERIC_COOKIE,
          NGM_BINARY2ASCII,
          "binary2ascii",
          &ng_parse_ng_mesg_type,
          &ng_parse_ng_mesg_type
        },
        { 0 }
};

/************************************************************************
                        Node routines
************************************************************************/

/*
 * Instantiate a node of the requested type
 */
int
ng_make_node(const char *typename, node_p *nodepp)
{
        struct ng_type *type;
        int     error;

        /* Check that the type makes sense */
        if (typename == NULL) {
                TRAP_ERROR();
                return (EINVAL);
        }

        /* Locate the node type. If we fail we return. Do not try to load
         * module.
         */
        if ((type = ng_findtype(typename)) == NULL)
                return (ENXIO);

        /*
         * If we have a constructor, then make the node and
         * call the constructor to do type specific initialisation.
         */
        if (type->constructor != NULL) {
                if ((error = ng_make_node_common(type, nodepp)) == 0) {
                        if ((error = ((*type->constructor)(*nodepp))) != 0) {
                                NG_NODE_UNREF(*nodepp);
                        }
                }
        } else {
                /*
                 * Node has no constructor. We cannot ask for one
                 * to be made. It must be brought into existence by
                 * some external agency. The external agency should
                 * call ng_make_node_common() directly to get the
                 * netgraph part initialised.
                 */
                TRAP_ERROR();
                error = EINVAL;
        }
        return (error);
}

/*
 * Generic node creation. Called by node initialisation for externally
 * instantiated nodes (e.g. hardware, sockets, etc ).
 * The returned node has a reference count of 1.
 */
int
ng_make_node_common(struct ng_type *type, node_p *nodepp)
{
        node_p node;

        /* Require the node type to have been already installed */
        if (ng_findtype(type->name) == NULL) {
                TRAP_ERROR();
                return (EINVAL);
        }

        /* Make a node and try attach it to the type */
        NG_ALLOC_NODE(node);
        if (node == NULL) {
                TRAP_ERROR();
                return (ENOMEM);
        }
        node->nd_type = type;
        NG_NODE_REF(node);                              /* note reference */
        type->refs++;

        /* Initialize the reader/writer shared token */
        lwkt_token_init(&node->nd_token, type->name);

        /* Initialize hook list for new node */
        LIST_INIT(&node->nd_hooks);

        /* Get an ID and put us in the hash chain. */
        IDHASH_WLOCK();
        for (;;) { /* wrap protection, even if silly */
                node_p node2 = NULL;
                node->nd_ID = nextID++; /* 137/second for 1 year before wrap */

                /* Is there a problem with the new number? */
                NG_IDHASH_FIND(node->nd_ID, node2); /* already taken? */
                if ((node->nd_ID != 0) && (node2 == NULL)) {
                        break;
                }
        }
        ng_nodes++;
        if (ng_nodes * 2 > ng_ID_hmask)
                ng_ID_rehash();
        LIST_INSERT_HEAD(&ng_ID_hash[NG_IDHASH_FN(node->nd_ID)], node,
            nd_idnodes);
        IDHASH_WUNLOCK();

        /* Done */
        *nodepp = node;
        return (0);
}

/*
 * Forceably start the shutdown process on a node. Either call
 * its shutdown method, or do the default shutdown if there is
 * no type-specific method.
 *
 * We can only be called from a shutdown message, so we know we have
 * a writer lock, and therefore exclusive access.
 *
 * Persistent node types must have a type-specific method which
 * allocates a new node in which case, this one is irretrievably going away,
 * or cleans up anything it needs, and just makes the node valid again,
 * in which case we allow the node to survive.
 *
 * XXX We need to think of how to tell a persistent node that we
 * REALLY need to go away because the hardware has gone or we
 * are rebooting.... etc.
 */
void
ng_rmnode(node_p node, hook_p dummy1, void *dummy2, int dummy3)
{
        hook_p hook;

        /* Check if it's already shutting down */
        if ((node->nd_flags & NGF_CLOSING) != 0)
                return;

        if (node == &ng_deadnode) {
                kprintf ("shutdown called on deadnode\n");
                return;
        }

        /* Add an extra reference so it doesn't go away during this */
        NG_NODE_REF(node);

        /*
         * Mark it invalid so any newcomers know not to try use it
         * Also add our own mark so we can't recurse
         * note that NGF_INVALID does not do this as it's also set during
         * creation
         */
        node->nd_flags |= NGF_INVALID|NGF_CLOSING;

        /* If node has its pre-shutdown method, then call it first*/
        if (node->nd_type && node->nd_type->close)
                (*node->nd_type->close)(node);

        /* Notify all remaining connected nodes to disconnect */
        while ((hook = LIST_FIRST(&node->nd_hooks)) != NULL)
                ng_destroy_hook(hook);

        /* Ask the type if it has anything to do in this case */
        if (node->nd_type && node->nd_type->shutdown) {
                (*node->nd_type->shutdown)(node);
                if (NG_NODE_IS_VALID(node)) {
                        /*
                         * Well, blow me down if the node code hasn't declared
                         * that it doesn't want to die.
                         * Presumably it is a persistant node.
                         * If we REALLY want it to go away,
                         *  e.g. hardware going away,
                         * Our caller should set NGF_REALLY_DIE in nd_flags.
                         */
                        node->nd_flags &= ~(NGF_INVALID|NGF_CLOSING);
                        NG_NODE_UNREF(node); /* Assume they still have theirs */
                        return;
                }
        } else {                                /* do the default thing */
                NG_NODE_UNREF(node);
        }

        ng_unname(node); /* basically a NOP these days */

        /*
         * Remove extra reference, possibly the last
         * Possible other holders of references may include
         * timeout callouts, but theoretically the node's supposed to
         * have cancelled them. Possibly hardware dependencies may
         * force a driver to 'linger' with a reference.
         */
        NG_NODE_UNREF(node);
}

/*
 * Remove a reference to the node, possibly the last.
 * deadnode always acts as it it were the last.
 */
void
ng_unref_node(node_p node)
{

        if (node == &ng_deadnode)
                return;

        if (refcount_release(&node->nd_refs)) { /* we were the last */

                node->nd_type->refs--; /* XXX maybe should get types lock? */
                NAMEHASH_WLOCK();
                if (NG_NODE_HAS_NAME(node)) {
                        ng_named_nodes--;
                        LIST_REMOVE(node, nd_nodes);
                }
                NAMEHASH_WUNLOCK();

                IDHASH_WLOCK();
                ng_nodes--;
                LIST_REMOVE(node, nd_idnodes);
                IDHASH_WUNLOCK();

                NG_FREE_NODE(node);
        }
}

/************************************************************************
                        Node ID handling
************************************************************************/
static node_p
ng_ID2noderef(ng_ID_t ID)
{
        node_p node;

        IDHASH_RLOCK();
        NG_IDHASH_FIND(ID, node);
        if (node)
                NG_NODE_REF(node);
        IDHASH_RUNLOCK();
        return(node);
}

ng_ID_t
ng_node2ID(node_p node)
{
        return (node ? NG_NODE_ID(node) : 0);
}

/************************************************************************
                        Node name handling
************************************************************************/

/*
 * Assign a node a name.
 */
int
ng_name_node(node_p node, const char *name)
{
        uint32_t hash;
        node_p node2;
        int i;

        /* Check the name is valid */
        for (i = 0; i < NG_NODESIZ; i++) {
                if (name[i] == '\0' || name[i] == '.' || name[i] == ':')
                        break;
        }
        if (i == 0 || name[i] != '\0') {
                TRAP_ERROR();
                return (EINVAL);
        }
        if (ng_decodeidname(name) != 0) { /* valid IDs not allowed here */
                TRAP_ERROR();
                return (EINVAL);
        }

        NAMEHASH_WLOCK();
        if (ng_named_nodes * 2 > ng_name_hmask)
                ng_name_rehash();

        hash = hash32_str(name, HASHINIT) & ng_name_hmask;
        /* Check the name isn't already being used. */
        LIST_FOREACH(node2, &ng_name_hash[hash], nd_nodes)
                if (NG_NODE_IS_VALID(node2) &&
                    (strcmp(NG_NODE_NAME(node2), name) == 0)) {
                        NAMEHASH_WUNLOCK();
                        return (EADDRINUSE);
                }

        if (NG_NODE_HAS_NAME(node))
                LIST_REMOVE(node, nd_nodes);
        else
                ng_named_nodes++;
        /* Copy it. */
        strlcpy(NG_NODE_NAME(node), name, NG_NODESIZ);

        /* Update name hash. */
        LIST_INSERT_HEAD(&ng_name_hash[hash], node, nd_nodes);
        NAMEHASH_WUNLOCK();

        return (0);
}

/*
 * Find a node by absolute name. The name should NOT end with ':'
 * The name "." means "this node" and "[xxx]" means "the node
 * with ID (ie, at address) xxx".
 *
 * Returns the node if found, else NULL.
 * Eventually should add something faster than a sequential search.
 * Note it acquires a reference on the node so you can be sure it's still
 * there.
 */
node_p
ng_name2noderef(node_p here, const char *name)
{
        node_p node;
        ng_ID_t temp;
        int     hash;

        /* "." means "this node" */
        if (strcmp(name, ".") == 0) {
                NG_NODE_REF(here);
                return(here);
        }

        /* Check for name-by-ID */
        if ((temp = ng_decodeidname(name)) != 0) {
                return (ng_ID2noderef(temp));
        }

        /* Find node by name. */
        hash = hash32_str(name, HASHINIT) & ng_name_hmask;
        NAMEHASH_RLOCK();
        LIST_FOREACH(node, &ng_name_hash[hash], nd_nodes)
                if (NG_NODE_IS_VALID(node) &&
                    (strcmp(NG_NODE_NAME(node), name) == 0)) {
                        NG_NODE_REF(node);
                        break;
                }
        NAMEHASH_RUNLOCK();

        return (node);
}

/*
 * Decode an ID name, eg. "[f03034de]". Returns 0 if the
 * string is not valid, otherwise returns the value.
 */
static ng_ID_t
ng_decodeidname(const char *name)
{
        const int len = strlen(name);
        char *eptr;
        u_long val;

        /* Check for proper length, brackets, no leading junk */
        if ((len < 3)
        || (name[0] != '[')
        || (name[len - 1] != ']')
        || (!isxdigit(name[1]))) {
                return ((ng_ID_t)0);
        }

        /* Decode number */
        val = strtoul(name + 1, &eptr, 16);
        if ((eptr - name != len - 1)
        || (val == ULONG_MAX)
        || (val == 0)) {
                return ((ng_ID_t)0);
        }
        return (ng_ID_t)val;
}

/*
 * Remove a name from a node. This should only be called
 * when shutting down and removing the node.
 */
void
ng_unname(node_p node)
{
}

/*
 * Allocate a bigger name hash.
 */
static void
ng_name_rehash(void)
{
        struct nodehash *new;
        uint32_t hash;
        u_long hmask;
        node_p node, node2;
        int i;

        NAMEHASH_ASSERT_LOCKED();
        new = hashinit((ng_name_hmask + 1) * 2, M_NETGRAPH_NODE, &hmask);
        if (new == NULL)
                return;

        for (i = 0; i <= ng_name_hmask; i++) {
                LIST_FOREACH_MUTABLE(node, &ng_name_hash[i], nd_nodes, node2) {
#ifdef INVARIANTS
                        LIST_REMOVE(node, nd_nodes);
#endif
                        hash = hash32_str(NG_NODE_NAME(node), HASHINIT) & hmask;
                        LIST_INSERT_HEAD(&new[hash], node, nd_nodes);
                }
        }

        hashdestroy(ng_name_hash, M_NETGRAPH_NODE, ng_name_hmask);
        ng_name_hash = new;
        ng_name_hmask = hmask;
}

/*
 * Allocate a bigger ID hash.
 */
static void
ng_ID_rehash(void)
{
        struct nodehash *new;
        uint32_t hash;
        u_long hmask;
        node_p node, node2;
        int i;

        IDHASH_ASSERT_LOCKED();
        new = hashinit((ng_ID_hmask + 1) * 2, M_NETGRAPH_NODE, &hmask);
        if (new == NULL)
                return;

        for (i = 0; i <= ng_ID_hmask; i++) {
                LIST_FOREACH_MUTABLE(node, &ng_ID_hash[i], nd_idnodes, node2) {
#ifdef INVARIANTS
                        LIST_REMOVE(node, nd_idnodes);
#endif
                        hash = (node->nd_ID % (hmask + 1));
                        LIST_INSERT_HEAD(&new[hash], node, nd_idnodes);
                }
        }

        hashdestroy(ng_ID_hash, M_NETGRAPH_NODE, ng_name_hmask);
        ng_ID_hash = new;
        ng_ID_hmask = hmask;
}

/************************************************************************
                        Hook routines
 Names are not optional. Hooks are always connected, except for a
 brief moment within these routines. On invalidation or during creation
 they are connected to the 'dead' hook.
************************************************************************/

/*
 * Remove a hook reference
 */
void
ng_unref_hook(hook_p hook)
{
        int v;

        if (hook == &ng_deadhook) {
                return;
        }

        v = atomic_fetchadd_int(&hook->hk_refs, -1);

        if (v == 1) { /* we were the last */
                if (_NG_HOOK_NODE(hook)) /* it'll probably be ng_deadnode */
                        _NG_NODE_UNREF((_NG_HOOK_NODE(hook)));
                NG_FREE_HOOK(hook);
        }
}

/*
 * Add an unconnected hook to a node. Only used internally.
 * Assumes node is locked. (XXX not yet true )
 */
static int
ng_add_hook(node_p node, const char *name, hook_p *hookp)
{
        hook_p hook;
        int error = 0;

        /* Check that the given name is good */
        if (name == NULL) {
                TRAP_ERROR();
                return (EINVAL);
        }
        if (ng_findhook(node, name) != NULL) {
                TRAP_ERROR();
                return (EEXIST);
        }

        /* Allocate the hook and link it up */
        NG_ALLOC_HOOK(hook);
        if (hook == NULL) {
                TRAP_ERROR();
                return (ENOMEM);
        }
        hook->hk_refs = 1;              /* add a reference for us to return */
        hook->hk_flags = HK_INVALID;
        hook->hk_peer = &ng_deadhook;   /* start off this way */
        hook->hk_node = node;
        NG_NODE_REF(node);              /* each hook counts as a reference */

        /* Set hook name */
        strlcpy(NG_HOOK_NAME(hook), name, NG_HOOKSIZ);

        /*
         * Check if the node type code has something to say about it
         * If it fails, the unref of the hook will also unref the node.
         */
        if (node->nd_type->newhook != NULL) {
                if ((error = (*node->nd_type->newhook)(node, hook, name))) {
                        NG_HOOK_UNREF(hook);    /* this frees the hook */
                        return (error);
                }
        }
        /*
         * The 'type' agrees so far, so go ahead and link it in.
         * We'll ask again later when we actually connect the hooks.
         */
        LIST_INSERT_HEAD(&node->nd_hooks, hook, hk_hooks);
        node->nd_numhooks++;
        NG_HOOK_REF(hook);      /* one for the node */

        if (hookp)
                *hookp = hook;
        return (0);
}

/*
 * Find a hook
 *
 * Node types may supply their own optimized routines for finding
 * hooks.  If none is supplied, we just do a linear search.
 * XXX Possibly we should add a reference to the hook?
 */
hook_p
ng_findhook(node_p node, const char *name)
{
        hook_p hook;

        if (node->nd_type->findhook != NULL)
                return (*node->nd_type->findhook)(node, name);
        LIST_FOREACH(hook, &node->nd_hooks, hk_hooks) {
                if (NG_HOOK_IS_VALID(hook)
                && (strcmp(NG_HOOK_NAME(hook), name) == 0))
                        return (hook);
        }
        return (NULL);
}

/*
 * Destroy a hook
 *
 * As hooks are always attached, this really destroys two hooks.
 * The one given, and the one attached to it. Disconnect the hooks
 * from each other first. We reconnect the peer hook to the 'dead'
 * hook so that it can still exist after we depart. We then
 * send the peer its own destroy message. This ensures that we only
 * interact with the peer's structures when it is locked processing that
 * message. We hold a reference to the peer hook so we are guaranteed that
 * the peer hook and node are still going to exist until
 * we are finished there as the hook holds a ref on the node.
 * We run this same code again on the peer hook, but that time it is already
 * attached to the 'dead' hook.
 *
 * This routine is called at all stages of hook creation
 * on error detection and must be able to handle any such stage.
 */
void
ng_destroy_hook(hook_p hook)
{
        hook_p peer;
        node_p node;

        if (hook == &ng_deadhook) {     /* better safe than sorry */
                kprintf("ng_destroy_hook called on deadhook\n");
                return;
        }

        /*
         * Protect divorce process with mutex, to avoid races on
         * simultaneous disconnect.
         */
        TOPOLOGY_WLOCK();

        hook->hk_flags |= HK_INVALID;

        peer = NG_HOOK_PEER(hook);
        node = NG_HOOK_NODE(hook);

        if (peer && (peer != &ng_deadhook)) {
                /*
                 * Set the peer to point to ng_deadhook
                 * from this moment on we are effectively independent it.
                 * send it an rmhook message of it's own.
                 */
                peer->hk_peer = &ng_deadhook;   /* They no longer know us */
                hook->hk_peer = &ng_deadhook;   /* Nor us, them */
                if (NG_HOOK_NODE(peer) == &ng_deadnode) {
                        /*
                         * If it's already divorced from a node,
                         * just free it.
                         */
                        TOPOLOGY_WUNLOCK();
                } else {
                        TOPOLOGY_WUNLOCK();
                        ng_rmhook_self(peer);   /* Send it a surprise */
                }
                NG_HOOK_UNREF(peer);            /* account for peer link */
                NG_HOOK_UNREF(hook);            /* account for peer link */
        } else
                TOPOLOGY_WUNLOCK();

        TOPOLOGY_NOTOWNED();

        /*
         * Remove the hook from the node's list to avoid possible recursion
         * in case the disconnection results in node shutdown.
         */
        if (node == &ng_deadnode) { /* happens if called from ng_con_nodes() */
                return;
        }
        LIST_REMOVE(hook, hk_hooks);
        node->nd_numhooks--;
        if (node->nd_type->disconnect) {
                /*
                 * The type handler may elect to destroy the node so don't
                 * trust its existence after this point. (except
                 * that we still hold a reference on it. (which we
                 * inherrited from the hook we are destroying)
                 */
                (*node->nd_type->disconnect) (hook);
        }

        /*
         * Note that because we will point to ng_deadnode, the original node
         * is not decremented automatically so we do that manually.
         */
        _NG_HOOK_NODE(hook) = &ng_deadnode;
        NG_NODE_UNREF(node);    /* We no longer point to it so adjust count */
        NG_HOOK_UNREF(hook);    /* Account for linkage (in list) to node */
}

/*
 * Take two hooks on a node and merge the connection so that the given node
 * is effectively bypassed.
 */
int
ng_bypass(hook_p hook1, hook_p hook2)
{
        if (hook1->hk_node != hook2->hk_node) {
                TRAP_ERROR();
                return (EINVAL);
        }
        hook1->hk_peer->hk_peer = hook2->hk_peer;
        hook2->hk_peer->hk_peer = hook1->hk_peer;

        hook1->hk_peer = &ng_deadhook;
        hook2->hk_peer = &ng_deadhook;

        NG_HOOK_UNREF(hook1);
        NG_HOOK_UNREF(hook2);

        /* XXX If we ever cache methods on hooks update them as well */
        ng_destroy_hook(hook1);
        ng_destroy_hook(hook2);
        return (0);
}

/*
 * Install a new netgraph type
 */
int
ng_newtype(struct ng_type *tp)
{
        const size_t namelen = strlen(tp->name);

        /* Check version and type name fields */
        if ((tp->version != NG_ABI_VERSION)
        || (namelen == 0)
        || (namelen >= NG_TYPESIZ)) {
                TRAP_ERROR();
                if (tp->version != NG_ABI_VERSION) {
                        kprintf("Netgraph: Node type rejected. ABI mismatch. Suggest recompile\n");
                }
                return (EINVAL);
        }

        /* Check for name collision */
        if (ng_findtype(tp->name) != NULL) {
                TRAP_ERROR();
                return (EEXIST);
        }

        /* Link in new type */
        TYPELIST_WLOCK();
        LIST_INSERT_HEAD(&ng_typelist, tp, types);
        tp->refs = 1;   /* first ref is linked list */
        TYPELIST_WUNLOCK();
        return (0);
}

/*
 * unlink a netgraph type
 * If no examples exist
 */
int
ng_rmtype(struct ng_type *tp)
{
        /* Check for name collision */
        if (tp->refs != 1) {
                TRAP_ERROR();
                return (EBUSY);
        }

        /* Unlink type */
        TYPELIST_WLOCK();
        LIST_REMOVE(tp, types);
        TYPELIST_WUNLOCK();
        return (0);
}

/*
 * Look for a type of the name given
 */
struct ng_type *
ng_findtype(const char *typename)
{
        struct ng_type *type;

        TYPELIST_RLOCK();
        LIST_FOREACH(type, &ng_typelist, types) {
                if (strcmp(type->name, typename) == 0)
                        break;
        }
        TYPELIST_RUNLOCK();
        return (type);
}

/************************************************************************
                        Composite routines
************************************************************************/
/*
 * Connect two nodes using the specified hooks, using queued functions.
 */
static int
ng_con_part3(node_p node, item_p item, hook_p hook)
{
        int     error = 0;

        /*
         * When we run, we know that the node 'node' is locked for us.
         * Our caller has a reference on the hook.
         * Our caller has a reference on the node.
         * (In this case our caller is ng_apply_item() ).
         * The peer hook has a reference on the hook.
         * We are all set up except for the final call to the node, and
         * the clearing of the INVALID flag.
         */
        if (NG_HOOK_NODE(hook) == &ng_deadnode) {
                /*
                 * The node must have been freed again since we last visited
                 * here. ng_destry_hook() has this effect but nothing else does.
                 * We should just release our references and
                 * free anything we can think of.
                 * Since we know it's been destroyed, and it's our caller
                 * that holds the references, just return.
                 */
                ERROUT(ENOENT);
        }
        if (hook->hk_node->nd_type->connect) {
                if ((error = (*hook->hk_node->nd_type->connect) (hook))) {
                        ng_destroy_hook(hook);  /* also zaps peer */
                        kprintf("failed in ng_con_part3()\n");
                        ERROUT(error);
                }
        }
        /*
         *  XXX this is wrong for SMP. Possibly we need
         * to separate out 'create' and 'invalid' flags.
         * should only set flags on hooks we have locked under our node.
         */
        hook->hk_flags &= ~HK_INVALID;
done:
        NG_FREE_ITEM(item);
        return (error);
}

static int
ng_con_part2(node_p node, item_p item, hook_p hook)
{
        hook_p  peer;
        int     error = 0;

        /*
         * When we run, we know that the node 'node' is locked for us.
         * Our caller has a reference on the hook.
         * Our caller has a reference on the node.
         * (In this case our caller is ng_apply_item() ).
         * The peer hook has a reference on the hook.
         * our node pointer points to the 'dead' node.
         * First check the hook name is unique.
         * Should not happen because we checked before queueing this.
         */
        if (ng_findhook(node, NG_HOOK_NAME(hook)) != NULL) {
                TRAP_ERROR();
                ng_destroy_hook(hook); /* should destroy peer too */
                kprintf("failed in ng_con_part2()\n");
                ERROUT(EEXIST);
        }
        /*
         * Check if the node type code has something to say about it
         * If it fails, the unref of the hook will also unref the attached node,
         * however since that node is 'ng_deadnode' this will do nothing.
         * The peer hook will also be destroyed.
         */
        if (node->nd_type->newhook != NULL) {
                if ((error = (*node->nd_type->newhook)(node, hook,
                    hook->hk_name))) {
                        ng_destroy_hook(hook); /* should destroy peer too */
                        kprintf("failed in ng_con_part2()\n");
                        ERROUT(error);
                }
        }

        /*
         * The 'type' agrees so far, so go ahead and link it in.
         * We'll ask again later when we actually connect the hooks.
         */
        hook->hk_node = node;           /* just overwrite ng_deadnode */
        NG_NODE_REF(node);              /* each hook counts as a reference */
        LIST_INSERT_HEAD(&node->nd_hooks, hook, hk_hooks);
        node->nd_numhooks++;
        NG_HOOK_REF(hook);      /* one for the node */
        
        /*
         * We now have a symmetrical situation, where both hooks have been
         * linked to their nodes, the newhook methods have been called
         * And the references are all correct. The hooks are still marked
         * as invalid, as we have not called the 'connect' methods
         * yet.
         * We can call the local one immediately as we have the
         * node locked, but we need to queue the remote one.
         */
        if (hook->hk_node->nd_type->connect) {
                if ((error = (*hook->hk_node->nd_type->connect) (hook))) {
                        ng_destroy_hook(hook);  /* also zaps peer */
                        kprintf("failed in ng_con_part2(A)\n");
                        ERROUT(error);
                }
        }

        /*
         * Acquire topo token to avoid race with ng_destroy_hook().
         */
        TOPOLOGY_RLOCK();
        peer = hook->hk_peer;
        if (peer == &ng_deadhook) {
                TOPOLOGY_RUNLOCK();
                kprintf("failed in ng_con_part2(B)\n");
                ng_destroy_hook(hook);
                ERROUT(ENOENT);
        }
        TOPOLOGY_RUNLOCK();

        if ((error = ng_send_fn2(peer->hk_node, peer, item, &ng_con_part3,
            NULL, 0, NG_REUSE_ITEM))) {
                kprintf("failed in ng_con_part2(C)\n");
                ng_destroy_hook(hook);  /* also zaps peer */
                return (error);         /* item was consumed. */
        }
        hook->hk_flags &= ~HK_INVALID; /* need both to be able to work */
        return (0);                     /* item was consumed. */
done:
        NG_FREE_ITEM(item);
        return (error);
}

/*
 * Connect this node with another node. We assume that this node is
 * currently locked, as we are only called from an NGM_CONNECT message.
 */
static int
ng_con_nodes(item_p item, node_p node, const char *name,
    node_p node2, const char *name2)
{
        int     error;
        hook_p  hook;
        hook_p  hook2;

        if (ng_findhook(node2, name2) != NULL) {
                return(EEXIST);
        }
        if ((error = ng_add_hook(node, name, &hook)))  /* gives us a ref */
                return (error);
        /* Allocate the other hook and link it up */
        NG_ALLOC_HOOK(hook2);
        if (hook2 == NULL) {
                TRAP_ERROR();
                ng_destroy_hook(hook);  /* XXX check ref counts so far */
                NG_HOOK_UNREF(hook);    /* including our ref */
                return (ENOMEM);
        }
        hook2->hk_refs = 1;             /* start with a reference for us. */
        hook2->hk_flags = HK_INVALID;
        hook2->hk_peer = hook;          /* Link the two together */
        hook->hk_peer = hook2;  
        NG_HOOK_REF(hook);              /* Add a ref for the peer to each*/
        NG_HOOK_REF(hook2);
        hook2->hk_node = &ng_deadnode;
        strlcpy(NG_HOOK_NAME(hook2), name2, NG_HOOKSIZ);

        /*
         * Queue the function above.
         * Procesing continues in that function in the lock context of
         * the other node.
         */
        if ((error = ng_send_fn2(node2, hook2, item, &ng_con_part2, NULL, 0,
            NG_NOFLAGS))) {
                kprintf("failed in ng_con_nodes(): %d\n", error);
                ng_destroy_hook(hook);  /* also zaps peer */
        }

        NG_HOOK_UNREF(hook);            /* Let each hook go if it wants to */
        NG_HOOK_UNREF(hook2);
        return (error);
}

/*
 * Make a peer and connect.
 * We assume that the local node is locked.
 * The new node probably doesn't need a lock until
 * it has a hook, because it cannot really have any work until then,
 * but we should think about it a bit more.
 *
 * The problem may come if the other node also fires up
 * some hardware or a timer or some other source of activation,
 * also it may already get a command msg via it's ID.
 *
 * We could use the same method as ng_con_nodes() but we'd have
 * to add ability to remove the node when failing. (Not hard, just
 * make arg1 point to the node to remove).
 * Unless of course we just ignore failure to connect and leave
 * an unconnected node?
 */
static int
ng_mkpeer(node_p node, const char *name, const char *name2, char *type)
{
        node_p  node2;
        hook_p  hook1, hook2;
        int     error;

        if ((error = ng_make_node(type, &node2))) {
                return (error);
        }

        if ((error = ng_add_hook(node, name, &hook1))) { /* gives us a ref */
                ng_rmnode(node2, NULL, NULL, 0);
                return (error);
        }

        if ((error = ng_add_hook(node2, name2, &hook2))) {
                ng_rmnode(node2, NULL, NULL, 0);
                ng_destroy_hook(hook1);
                NG_HOOK_UNREF(hook1);
                return (error);
        }

        /*
         * Actually link the two hooks together.
         */
        hook1->hk_peer = hook2;
        hook2->hk_peer = hook1;

        /* Each hook is referenced by the other */
        NG_HOOK_REF(hook1);
        NG_HOOK_REF(hook2);

        /* Give each node the opportunity to veto the pending connection */
        if (hook1->hk_node->nd_type->connect) {
                error = (*hook1->hk_node->nd_type->connect) (hook1);
        }

        if ((error == 0) && hook2->hk_node->nd_type->connect) {
                error = (*hook2->hk_node->nd_type->connect) (hook2);

        }

        /*
         * drop the references we were holding on the two hooks.
         */
        if (error) {
                ng_destroy_hook(hook2); /* also zaps hook1 */
                ng_rmnode(node2, NULL, NULL, 0);
        } else {
                /* As a last act, allow the hooks to be used */
                hook1->hk_flags &= ~HK_INVALID;
                hook2->hk_flags &= ~HK_INVALID;
        }
        NG_HOOK_UNREF(hook1);
        NG_HOOK_UNREF(hook2);
        return (error);
}

/************************************************************************
                Utility routines to send self messages
************************************************************************/
        
/* Shut this node down as soon as everyone is clear of it */
/* Should add arg "immediately" to jump the queue */
int
ng_rmnode_self(node_p node)
{
        int             error;

        if (node == &ng_deadnode)
                return (0);
        node->nd_flags |= NGF_INVALID;
        if (node->nd_flags & NGF_CLOSING)
                return (0);

        error = ng_send_fn(node, NULL, &ng_rmnode, NULL, 0);
        return (error);
}

static void
ng_rmhook_part2(node_p node, hook_p hook, void *arg1, int arg2)
{
        ng_destroy_hook(hook);
        return ;
}

int
ng_rmhook_self(hook_p hook)
{
        int             error;
        node_p node = NG_HOOK_NODE(hook);

        if (node == &ng_deadnode)
                return (0);

        error = ng_send_fn(node, hook, &ng_rmhook_part2, NULL, 0);
        return (error);
}

/***********************************************************************
 * Parse and verify a string of the form:  <NODE:><PATH>
 *
 * Such a string can refer to a specific node or a specific hook
 * on a specific node, depending on how you look at it. In the
 * latter case, the PATH component must not end in a dot.
 *
 * Both <NODE:> and <PATH> are optional. The <PATH> is a string
 * of hook names separated by dots. This breaks out the original
 * string, setting *nodep to "NODE" (or NULL if none) and *pathp
 * to "PATH" (or NULL if degenerate). Also, *hookp will point to
 * the final hook component of <PATH>, if any, otherwise NULL.
 *
 * This returns -1 if the path is malformed. The char ** are optional.
 ***********************************************************************/
int
ng_path_parse(char *addr, char **nodep, char **pathp, char **hookp)
{
        char    *node, *path, *hook;
        int     k;

        /*
         * Extract absolute NODE, if any
         */
        for (path = addr; *path && *path != ':'; path++);
        if (*path) {
                node = addr;    /* Here's the NODE */
                *path++ = '\0'; /* Here's the PATH */

                /* Node name must not be empty */
                if (!*node)
                        return -1;

                /* A name of "." is OK; otherwise '.' not allowed */
                if (strcmp(node, ".") != 0) {
                        for (k = 0; node[k]; k++)
                                if (node[k] == '.')
                                        return -1;
                }
        } else {
                node = NULL;    /* No absolute NODE */
                path = addr;    /* Here's the PATH */
        }

        /* Snoop for illegal characters in PATH */
        for (k = 0; path[k]; k++)
                if (path[k] == ':')
                        return -1;

        /* Check for no repeated dots in PATH */
        for (k = 0; path[k]; k++)
                if (path[k] == '.' && path[k + 1] == '.')
                        return -1;

        /* Remove extra (degenerate) dots from beginning or end of PATH */
        if (path[0] == '.')
                path++;
        if (*path && path[strlen(path) - 1] == '.')
                path[strlen(path) - 1] = 0;

        /* If PATH has a dot, then we're not talking about a hook */
        if (*path) {
                for (hook = path, k = 0; path[k]; k++)
                        if (path[k] == '.') {
                                hook = NULL;
                                break;
                        }
        } else
                path = hook = NULL;

        /* Done */
        if (nodep)
                *nodep = node;
        if (pathp)
                *pathp = path;
        if (hookp)
                *hookp = hook;
        return (0);
}

/*
 * Given a path, which may be absolute or relative, and a starting node,
 * return the destination node.
 */
int
ng_path2noderef(node_p here, const char *address,
                                node_p *destp, hook_p *lasthook)
{
        char    fullpath[NG_PATHSIZ];
        char   *nodename, *path, pbuf[2];
        node_p  node, oldnode;
        char   *cp;
        hook_p hook = NULL;

        /* Initialize */
        if (destp == NULL) {
                TRAP_ERROR();
                return EINVAL;
        }
        *destp = NULL;

        /* Make a writable copy of address for ng_path_parse() */
        strncpy(fullpath, address, sizeof(fullpath) - 1);
        fullpath[sizeof(fullpath) - 1] = '\0';

        /* Parse out node and sequence of hooks */
        if (ng_path_parse(fullpath, &nodename, &path, NULL) < 0) {
                TRAP_ERROR();
                return EINVAL;
        }
        if (path == NULL) {
                pbuf[0] = '.';  /* Needs to be writable */
                pbuf[1] = '\0';
                path = pbuf;
        }

        /*
         * For an absolute address, jump to the starting node.
         * Note that this holds a reference on the node for us.
         * Don't forget to drop the reference if we don't need it.
         */
        if (nodename) {
                node = ng_name2noderef(here, nodename);
                if (node == NULL) {
                        TRAP_ERROR();
                        return (ENOENT);
                }
        } else {
                if (here == NULL) {
                        TRAP_ERROR();
                        return (EINVAL);
                }
                node = here;
                NG_NODE_REF(node);
        }

        /*
         * Now follow the sequence of hooks
         * XXX
         * We actually cannot guarantee that the sequence
         * is not being demolished as we crawl along it
         * without extra-ordinary locking etc.
         * So this is a bit dodgy to say the least.
         * We can probably hold up some things by holding
         * the nodelist mutex for the time of this
         * crawl if we wanted.. At least that way we wouldn't have to
         * worry about the nodes disappearing, but the hooks would still
         * be a problem.
         */
        for (cp = path; node != NULL && *cp != '\0'; ) {
                char *segment;

                /*
                 * Break out the next path segment. Replace the dot we just
                 * found with a NUL; "cp" points to the next segment (or the
                 * NUL at the end).
                 */
                for (segment = cp; *cp != '\0'; cp++) {
                        if (*cp == '.') {
                                *cp++ = '\0';
                                break;
                        }
                }

                /* Empty segment */
                if (*segment == '\0')
                        continue;

                /* We have a segment, so look for a hook by that name */
                hook = ng_findhook(node, segment);

                /* Can't get there from here... */
                if (hook == NULL
                    || NG_HOOK_PEER(hook) == NULL
                    || NG_HOOK_NOT_VALID(hook)
                    || NG_HOOK_NOT_VALID(NG_HOOK_PEER(hook))) {
                        TRAP_ERROR();
                        NG_NODE_UNREF(node);
#if 0
                        kprintf("hooknotvalid %s %s %d %d %d %d ",
                                        path,
                                        segment,
                                        hook == NULL,
                                        NG_HOOK_PEER(hook) == NULL,
                                        NG_HOOK_NOT_VALID(hook),
                                        NG_HOOK_NOT_VALID(NG_HOOK_PEER(hook)));
#endif
                        return (ENOENT);
                }

                /*
                 * Hop on over to the next node
                 * XXX
                 * Big race conditions here as hooks and nodes go away
                 * *** Idea.. store an ng_ID_t in each hook and use that
                 * instead of the direct hook in this crawl?
                 */
                oldnode = node;
                if ((node = NG_PEER_NODE(hook)))
                        NG_NODE_REF(node);      /* XXX RACE */
                NG_NODE_UNREF(oldnode); /* XXX another race */
                if (NG_NODE_NOT_VALID(node)) {
                        NG_NODE_UNREF(node);    /* XXX more races */
                        node = NULL;
                }
        }

        /* If node somehow missing, fail here (probably this is not needed) */
        if (node == NULL) {
                TRAP_ERROR();
                return (ENXIO);
        }

        /* Done */
        *destp = node;
        if (lasthook != NULL)
                *lasthook = (hook ? NG_HOOK_PEER(hook) : NULL);
        return (0);
}

/*********************************************************************\
* Inter-CPU node synchronization
*
* All activities are submitted to one of the netgraph per-CPU threads.
* There is one item input queue per CPU, not one per node as in
* FreeBSD.  If the item is entering netgraph for the first time, it is
* queued to the thread's msgport.  Otherwise it is applied directly.
* From start to finish, the item is processed on the same CPU.  Items
* are distributed based on the ingress node, to keep item ordering.
\***************************************************************/

static __inline void    ng_acquire_read(node_p node);
static __inline void    ng_acquire_write(node_p node);
static __inline void    ng_leave_readwrite(node_p node);

static __inline void
ng_acquire_read(node_p node)
{
        KASSERT(node != &ng_deadnode,
            ("%s: working on deadnode", __func__));

        lwkt_gettoken_shared(&node->nd_token);
}

/* Acquire writer lock on node. If node is busy, sleep. */
static __inline void
ng_acquire_write(node_p node)
{
        KASSERT(node != &ng_deadnode,
            ("%s: working on deadnode", __func__));

        lwkt_gettoken(&node->nd_token);
}

/* Release reader or writer lock. */
static __inline void
ng_leave_readwrite(node_p node)
{
        lwkt_reltoken(&node->nd_token);
}

/***********************************************************************
* Worklist routines
**********************************************************************/
/* NETGRAPH thread routine
 *
 * Pick an item from our thread's queue and apply it.
 */
static void
ngthread(void *dummy __unused)
{
        lwkt_msg_t msg;

        while ((msg = lwkt_waitport(&curthread->td_msgport, 0)) != NULL) {
                item_p  item = (void *)msg;

                ng_apply_item(item);
                /* Do not reply to the message */
        }
}

/***********************************************************************
* Externally visible method for sending or queueing messages or data.
***********************************************************************/

/*
 * The module code should have filled out the item correctly by this stage:
 * Common:
 *    reference to destination node.
 *    Reference to destination rcv hook if relevant.
 *    apply pointer must be or NULL or reference valid struct ng_apply_info.
 * Data:
 *    pointer to mbuf
 * Control_Message:
 *    pointer to msg.
 *    ID of original sender node. (return address)
 * Function:
 *    Function pointer
 *    void * argument
 *    integer argument
 *
 * The nodes have several routines and macros to help with this task:
 */

int
ng_snd_item(item_p item, int flags)
{
        hook_p hook;
        node_p node;
        int error = 0;

        /* We are sending item, so it must be present! */
        KASSERT(item != NULL, ("ng_snd_item: item is NULL"));

#ifdef  NETGRAPH_DEBUG
        _ngi_check(item, __FILE__, __LINE__);
#endif

        /*
         * Every time an item is sent or forwarded we hold a reference on it
         * to postone the callback (if there is one) and item freedom.
         */
        ng_ref_item(item);

        /*
         * Node is never optional.
         */
        node = NGI_NODE(item);
        KASSERT(node != NULL, ("ng_snd_item: node is NULL"));

        /*
         * Valid hook and mbuf are mandatory for data.
         */
        hook = NGI_HOOK(item);
        if ((item->el_flags & NGQF_TYPE) == NGQF_DATA) {
                KASSERT(hook != NULL, ("ng_snd_item: hook for data is NULL"));
                if (NGI_M(item) == NULL)
                        ERROUT(EINVAL);
                CHECK_DATA_MBUF(NGI_M(item));
        }

        /*
         * Always queue items entering netgraph for the first time.
         */
        if (item->refs == 1) {
                struct lwkt_msg *msg = &item->el_lmsg;

                lwkt_initmsg(msg, &ng_panic_reply_port, 0);
                /* Always send to cpu0 for now */
                lwkt_sendmsg(ng_cpuport(0), msg);

                return ((flags & NG_PROGRESS) ? EINPROGRESS : 0);
        }

        /*
         * The item wasn't queued.  Process it synchronously.
         */
        error = ng_apply_item(item);

done:
        return (error);
}

/*
 * We have an item that was possibly queued somewhere.
 * It should contain all the information needed
 * to run it on the appropriate node/hook.
 * If there is apply pointer and we own the last reference, call apply().
 */
static int
ng_apply_item(item_p item)
{
        hook_p  hook;
        node_p  node;
        ng_rcvdata_t *rcvdata;
        ng_rcvmsg_t *rcvmsg;
        int     error = 0;

        /* Node and item are never optional. */
        KASSERT(item != NULL, ("ng_apply_item: item is NULL"));
        NGI_GET_NODE(item, node);               /* zaps stored node */
        KASSERT(node != NULL, ("ng_apply_item: node is NULL"));
        NGI_GET_HOOK(item, hook);               /* clears stored hook */

        /*
         * If the item or the node specifies single threading, force
         * writer semantics. Similarly, the node may say one hook always
         * produces writers. These are overrides.
         */
        if (((item->el_flags & NGQF_RW) == NGQF_WRITER) ||
            (node->nd_flags & NGF_FORCE_WRITER) ||
            (hook && (hook->hk_flags & HK_FORCE_WRITER))) {
                ng_acquire_write(node);
        } else {
                ng_acquire_read(node);
        }

#ifdef  NETGRAPH_DEBUG
        _ngi_check(item, __FILE__, __LINE__);
#endif

        switch (item->el_flags & NGQF_TYPE) {
        case NGQF_DATA:
                /*
                 * Check things are still ok as when we were queued.
                 */
                KASSERT(hook != NULL, ("ng_apply_item: hook for data is NULL"));
                if (NG_HOOK_NOT_VALID(hook) ||
                    NG_NODE_NOT_VALID(node)) {
                        error = EIO;
                        NG_FREE_ITEM(item);
                        break;
                }
                /*
                 * If no receive method, just silently drop it.
                 * Give preference to the hook over-ride method
                 */
                if ((!(rcvdata = hook->hk_rcvdata))
                && (!(rcvdata = NG_HOOK_NODE(hook)->nd_type->rcvdata))) {
                        error = 0;
                        NG_FREE_ITEM(item);
                        break;
                }
                error = (*rcvdata)(hook, item);
                break;
        case NGQF_MESG:
                if (hook && NG_HOOK_NOT_VALID(hook)) {
                        /*
                         * The hook has been zapped then we can't use it.
                         * Immediately drop its reference.
                         * The message may not need it.
                         */
                        NG_HOOK_UNREF(hook);
                        hook = NULL;
                }
                /*
                 * Similarly, if the node is a zombie there is
                 * nothing we can do with it, drop everything.
                 */
                if (NG_NODE_NOT_VALID(node)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        NG_FREE_ITEM(item);
                        break;
                }
                /*
                 * Call the appropriate message handler for the object.
                 * It is up to the message handler to free the message.
                 * If it's a generic message, handle it generically,
                 * otherwise call the type's message handler (if it exists).
                 * XXX (race). Remember that a queued message may
                 * reference a node or hook that has just been
                 * invalidated. It will exist as the queue code
                 * is holding a reference, but..
                 */
                if ((NGI_MSG(item)->header.typecookie == NGM_GENERIC_COOKIE) &&
                    ((NGI_MSG(item)->header.flags & NGF_RESP) == 0)) {
                        error = ng_generic_msg(node, item, hook);
                        break;
                }
                if (((!hook) || (!(rcvmsg = hook->hk_rcvmsg))) &&
                    (!(rcvmsg = node->nd_type->rcvmsg))) {
                        TRAP_ERROR();
                        error = 0;
                        NG_FREE_ITEM(item);
                        break;
                }
                error = (*rcvmsg)(node, item, hook);
                break;
        case NGQF_FN:
        case NGQF_FN2:
                /*
                 *  We have to implicitly trust the hook,
                 * as some of these are used for system purposes
                 * where the hook is invalid. In the case of
                 * the shutdown message we allow it to hit
                 * even if the node is invalid.
                 */
                if ((NG_NODE_NOT_VALID(node))
                && (NGI_FN(item) != &ng_rmnode)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        NG_FREE_ITEM(item);
                        break;
                }
                if ((item->el_flags & NGQF_TYPE) == NGQF_FN) {
                        (*NGI_FN(item))(node, hook, NGI_ARG1(item),
                            NGI_ARG2(item));
                        NG_FREE_ITEM(item);
                } else  /* it is NGQF_FN2 */
                        error = (*NGI_FN2(item))(node, item, hook);
                break;
        }
        /*
         * We held references on some of the resources
         * that we took from the item. Now that we have
         * finished doing everything, drop those references.
         */
        if (hook)
                NG_HOOK_UNREF(hook);

        /* Release our node's token */
        ng_leave_readwrite(node);

        /* Free the item if we own the last reference to it. */
        ng_unref_item(item, error);

        NG_NODE_UNREF(node);

        return (error);
}

/***********************************************************************
 * Implement the 'generic' control messages
 ***********************************************************************/
static int
ng_generic_msg(node_p here, item_p item, hook_p lasthook)
{
        int error = 0;
        struct ng_mesg *msg;
        struct ng_mesg *resp = NULL;

        NGI_GET_MSG(item, msg);
        if (msg->header.typecookie != NGM_GENERIC_COOKIE) {
                TRAP_ERROR();
                error = EINVAL;
                goto out;
        }
        switch (msg->header.cmd) {
        case NGM_SHUTDOWN:
                ng_rmnode(here, NULL, NULL, 0);
                break;
        case NGM_MKPEER:
            {
                struct ngm_mkpeer *const mkp = (struct ngm_mkpeer *) msg->data;

                if (msg->header.arglen != sizeof(*mkp)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        break;
                }
                mkp->type[sizeof(mkp->type) - 1] = '\0';
                mkp->ourhook[sizeof(mkp->ourhook) - 1] = '\0';
                mkp->peerhook[sizeof(mkp->peerhook) - 1] = '\0';
                error = ng_mkpeer(here, mkp->ourhook, mkp->peerhook, mkp->type);
                break;
            }
        case NGM_CONNECT:
            {
                struct ngm_connect *const con =
                        (struct ngm_connect *) msg->data;
                node_p node2;

                if (msg->header.arglen != sizeof(*con)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        break;
                }
                con->path[sizeof(con->path) - 1] = '\0';
                con->ourhook[sizeof(con->ourhook) - 1] = '\0';
                con->peerhook[sizeof(con->peerhook) - 1] = '\0';
                /* Don't forget we get a reference.. */
                error = ng_path2noderef(here, con->path, &node2, NULL);
                if (error)
                        break;
                error = ng_con_nodes(item, here, con->ourhook,
                    node2, con->peerhook);
                NG_NODE_UNREF(node2);
                break;
            }
        case NGM_NAME:
            {
                struct ngm_name *const nam = (struct ngm_name *) msg->data;

                if (msg->header.arglen != sizeof(*nam)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        break;
                }
                nam->name[sizeof(nam->name) - 1] = '\0';
                error = ng_name_node(here, nam->name);
                break;
            }
        case NGM_RMHOOK:
            {
                struct ngm_rmhook *const rmh = (struct ngm_rmhook *) msg->data;
                hook_p hook;

                if (msg->header.arglen != sizeof(*rmh)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        break;
                }
                rmh->ourhook[sizeof(rmh->ourhook) - 1] = '\0';
                if ((hook = ng_findhook(here, rmh->ourhook)) != NULL)
                        ng_destroy_hook(hook);
                break;
            }
        case NGM_NODEINFO:
            {
                struct nodeinfo *ni;

                NG_MKRESPONSE(resp, msg, sizeof(*ni), M_WAITOK | M_NULLOK);
                if (resp == NULL) {
                        error = ENOMEM;
                        break;
                }

                /* Fill in node info */
                ni = (struct nodeinfo *) resp->data;
                if (NG_NODE_HAS_NAME(here))
                        strcpy(ni->name, NG_NODE_NAME(here));
                strcpy(ni->type, here->nd_type->name);
                ni->id = ng_node2ID(here);
                ni->hooks = here->nd_numhooks;
                break;
            }
        case NGM_LISTHOOKS:
            {
                const int nhooks = here->nd_numhooks;
                struct hooklist *hl;
                struct nodeinfo *ni;
                hook_p hook;

                /* Get response struct */
                NG_MKRESPONSE(resp, msg, sizeof(*hl)
                    + (nhooks * sizeof(struct linkinfo)), M_WAITOK | M_NULLOK);
                if (resp == NULL) {
                        error = ENOMEM;
                        break;
                }
                hl = (struct hooklist *) resp->data;
                ni = &hl->nodeinfo;

                /* Fill in node info */
                if (NG_NODE_HAS_NAME(here))
                        strcpy(ni->name, NG_NODE_NAME(here));
                strcpy(ni->type, here->nd_type->name);
                ni->id = ng_node2ID(here);

                /* Cycle through the linked list of hooks */
                ni->hooks = 0;
                LIST_FOREACH(hook, &here->nd_hooks, hk_hooks) {
                        struct linkinfo *const link = &hl->link[ni->hooks];

                        if (ni->hooks >= nhooks) {
                                log(LOG_ERR, "%s: number of %s changed\n",
                                    __func__, "hooks");
                                break;
                        }
                        if (NG_HOOK_NOT_VALID(hook))
                                continue;
                        strcpy(link->ourhook, NG_HOOK_NAME(hook));
                        strcpy(link->peerhook, NG_PEER_HOOK_NAME(hook));
                        if (NG_PEER_NODE_NAME(hook)[0] != '\0')
                                strcpy(link->nodeinfo.name,
                                    NG_PEER_NODE_NAME(hook));
                        strcpy(link->nodeinfo.type,
                           NG_PEER_NODE(hook)->nd_type->name);
                        link->nodeinfo.id = ng_node2ID(NG_PEER_NODE(hook));
                        link->nodeinfo.hooks = NG_PEER_NODE(hook)->nd_numhooks;
                        ni->hooks++;
                }
                break;
            }

        case NGM_LISTNODES:
            {
                struct namelist *nl;
                node_p node;
                int i;

                IDHASH_RLOCK();
                /* Get response struct. */
                NG_MKRESPONSE(resp, msg, sizeof(*nl) +
                    (ng_nodes * sizeof(struct nodeinfo)), M_NOWAIT | M_ZERO);
                if (resp == NULL) {
                        IDHASH_RUNLOCK();
                        error = ENOMEM;
                        break;
                }
                nl = (struct namelist *) resp->data;

                /* Cycle through the lists of nodes. */
                nl->numnames = 0;
                for (i = 0; i <= ng_ID_hmask; i++) {
                        LIST_FOREACH(node, &ng_ID_hash[i], nd_idnodes) {
                                struct nodeinfo *const np =
                                    &nl->nodeinfo[nl->numnames];

                                if (NG_NODE_NOT_VALID(node))
                                        continue;
                                if (NG_NODE_HAS_NAME(node))
                                        strcpy(np->name, NG_NODE_NAME(node));
                                strcpy(np->type, node->nd_type->name);
                                np->id = ng_node2ID(node);
                                np->hooks = node->nd_numhooks;
                                KASSERT(nl->numnames < ng_nodes,
                                    ("%s: no space", __func__));
                                nl->numnames++;
                        }
                }
                IDHASH_RUNLOCK();
                break;
            }
        case NGM_LISTNAMES:
            {
                struct namelist *nl;
                node_p node;
                int i;

                NAMEHASH_RLOCK();
                /* Get response struct. */
                NG_MKRESPONSE(resp, msg, sizeof(*nl) +
                    (ng_named_nodes * sizeof(struct nodeinfo)), M_NOWAIT);
                if (resp == NULL) {
                        NAMEHASH_RUNLOCK();
                        error = ENOMEM;
                        break;
                }
                nl = (struct namelist *) resp->data;

                /* Cycle through the lists of nodes. */
                nl->numnames = 0;
                for (i = 0; i <= ng_name_hmask; i++) {
                        LIST_FOREACH(node, &ng_name_hash[i], nd_nodes) {
                                struct nodeinfo *const np =
                                    &nl->nodeinfo[nl->numnames];

                                if (NG_NODE_NOT_VALID(node))
                                        continue;
                                strcpy(np->name, NG_NODE_NAME(node));
                                strcpy(np->type, node->nd_type->name);
                                np->id = ng_node2ID(node);
                                np->hooks = node->nd_numhooks;
                                KASSERT(nl->numnames < ng_named_nodes,
                                    ("%s: no space", __func__));
                                nl->numnames++;
                        }
                }
                NAMEHASH_RUNLOCK();
                break;
            }

        case NGM_LISTTYPES:
            {
                struct typelist *tl;
                struct ng_type *type;
                int num = 0;

                TYPELIST_RLOCK();
                /* Count number of types */
                LIST_FOREACH(type, &ng_typelist, types)
                        num++;

                /* Get response struct */
                NG_MKRESPONSE(resp, msg, sizeof(*tl)
                    + (num * sizeof(struct typeinfo)), M_WAITOK | M_NULLOK);
                if (resp == NULL) {
                        TYPELIST_RUNLOCK();
                        error = ENOMEM;
                        break;
                }
                tl = (struct typelist *) resp->data;

                /* Cycle through the linked list of types */
                tl->numtypes = 0;
                LIST_FOREACH(type, &ng_typelist, types) {
                        struct typeinfo *const tp = &tl->typeinfo[tl->numtypes];

                        strcpy(tp->type_name, type->name);
                        tp->numnodes = type->refs - 1; /* don't count list */
                        KASSERT(tl->numtypes < num, ("%s: no space", __func__));
                        tl->numtypes++;
                }
                TYPELIST_RUNLOCK();
                break;
            }

        case NGM_BINARY2ASCII:
            {
                int bufSize = 20 * 1024;        /* XXX hard coded constant */
                const struct ng_parse_type *argstype;
                const struct ng_cmdlist *c;
                struct ng_mesg *binary, *ascii;

                /* Data area must contain a valid netgraph message */
                binary = (struct ng_mesg *)msg->data;
                if (msg->header.arglen < sizeof(struct ng_mesg) ||
                    (msg->header.arglen - sizeof(struct ng_mesg) <
                    binary->header.arglen)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        break;
                }

                /* Get a response message with lots of room */
                NG_MKRESPONSE(resp, msg, sizeof(*ascii) + bufSize, M_WAITOK | M_NULLOK);
                if (resp == NULL) {
                        error = ENOMEM;
                        break;
                }
                ascii = (struct ng_mesg *)resp->data;

                /* Copy binary message header to response message payload */
                bcopy(binary, ascii, sizeof(*binary));

                /* Find command by matching typecookie and command number */
                for (c = here->nd_type->cmdlist;
                    c != NULL && c->name != NULL; c++) {
                        if (binary->header.typecookie == c->cookie
                            && binary->header.cmd == c->cmd)
                                break;
                }
                if (c == NULL || c->name == NULL) {
                        for (c = ng_generic_cmds; c->name != NULL; c++) {
                                if (binary->header.typecookie == c->cookie
                                    && binary->header.cmd == c->cmd)
                                        break;
                        }
                        if (c->name == NULL) {
                                NG_FREE_MSG(resp);
                                error = ENOSYS;
                                break;
                        }
                }

                /* Convert command name to ASCII */
                ksnprintf(ascii->header.cmdstr, sizeof(ascii->header.cmdstr),
                    "%s", c->name);

                /* Convert command arguments to ASCII */
                argstype = (binary->header.flags & NGF_RESP) ?
                    c->respType : c->mesgType;
                if (argstype == NULL) {
                        *ascii->data = '\0';
                } else {
                        if ((error = ng_unparse(argstype,
                            (u_char *)binary->data,
                            ascii->data, bufSize)) != 0) {
                                NG_FREE_MSG(resp);
                                break;
                        }
                }

                /* Return the result as struct ng_mesg plus ASCII string */
                bufSize = strlen(ascii->data) + 1;
                ascii->header.arglen = bufSize;
                resp->header.arglen = sizeof(*ascii) + bufSize;
                break;
            }

        case NGM_ASCII2BINARY:
            {
                int bufSize = 2000;     /* XXX hard coded constant */
                const struct ng_cmdlist *c;
                const struct ng_parse_type *argstype;
                struct ng_mesg *ascii, *binary;
                int off = 0;

                /* Data area must contain at least a struct ng_mesg + '\0' */
                ascii = (struct ng_mesg *)msg->data;
                if ((msg->header.arglen < sizeof(*ascii) + 1) ||
                    (ascii->header.arglen < 1) ||
                    (msg->header.arglen < sizeof(*ascii) +
                    ascii->header.arglen)) {
                        TRAP_ERROR();
                        error = EINVAL;
                        break;
                }
                ascii->data[ascii->header.arglen - 1] = '\0';

                /* Get a response message with lots of room */
                NG_MKRESPONSE(resp, msg, sizeof(*binary) + bufSize, M_WAITOK | M_NULLOK);
                if (resp == NULL) {
                        error = ENOMEM;
                        break;
                }
                binary = (struct ng_mesg *)resp->data;

                /* Copy ASCII message header to response message payload */
                bcopy(ascii, binary, sizeof(*ascii));

                /* Find command by matching ASCII command string */
                for (c = here->nd_type->cmdlist;
                    c != NULL && c->name != NULL; c++) {
                        if (strcmp(ascii->header.cmdstr, c->name) == 0)
                                break;
                }
                if (c == NULL || c->name == NULL) {
                        for (c = ng_generic_cmds; c->name != NULL; c++) {
                                if (strcmp(ascii->header.cmdstr, c->name) == 0)
                                        break;
                        }
                        if (c->name == NULL) {
                                NG_FREE_MSG(resp);
                                error = ENOSYS;
                                break;
                        }
                }

                /* Convert command name to binary */
                binary->header.cmd = c->cmd;
                binary->header.typecookie = c->cookie;

                /* Convert command arguments to binary */
                argstype = (binary->header.flags & NGF_RESP) ?
                    c->respType : c->mesgType;
                if (argstype == NULL) {
                        bufSize = 0;
                } else {
                        if ((error = ng_parse(argstype, ascii->data,
                            &off, (u_char *)binary->data, &bufSize)) != 0) {
                                NG_FREE_MSG(resp);
                                break;
                        }
                }

                /* Return the result */
                binary->header.arglen = bufSize;
                resp->header.arglen = sizeof(*binary) + bufSize;
                break;
            }

        case NGM_TEXT_CONFIG:
        case NGM_TEXT_STATUS:
                /*
                 * This one is tricky as it passes the command down to the
                 * actual node, even though it is a generic type command.
                 * This means we must assume that the item/msg is already freed
                 * when control passes back to us.
                 */
                if (here->nd_type->rcvmsg != NULL) {
                        NGI_MSG(item) = msg; /* put it back as we found it */
                        return((*here->nd_type->rcvmsg)(here, item, lasthook));
                }
                /* Fall through if rcvmsg not supported */
        default:
                TRAP_ERROR();
                error = EINVAL;
        }
        /*
         * Sometimes a generic message may be statically allocated
         * to avoid problems with allocating when in tight memeory situations.
         * Don't free it if it is so.
         * I break them appart here, because erros may cause a free if the item
         * in which case we'd be doing it twice.
         * they are kept together above, to simplify freeing.
         */
out:
        NG_RESPOND_MSG(error, here, item, resp);
        if (msg)
                NG_FREE_MSG(msg);
        return (error);
}

/************************************************************************
                        Queue element get/free routines
************************************************************************/

static struct objcache  *ng_oc;
static struct objcache  *ng_apply_oc;
static int               maxalloc = 4096; /* limit the damage of a leak */

TUNABLE_INT("net.graph.maxalloc", &maxalloc);
SYSCTL_INT(_net_graph, OID_AUTO, maxalloc, CTLFLAG_RD, &maxalloc,
    0, "Maximum number of queue items to allocate");

#ifdef  NETGRAPH_DEBUG
static TAILQ_HEAD(, ng_item) ng_itemlist = TAILQ_HEAD_INITIALIZER(ng_itemlist);
static int                      allocated;      /* number of items malloc'd */
#endif

/*
 * Get a queue entry.
 * This is usually called when a packet first enters netgraph.
 * By definition, this is usually from an interrupt, or from a user.
 * Users are not so important, but try be quick for the times that it's
 * an interrupt.
 */
static __inline item_p
ng_alloc_item(int type, int flags)
{
        item_p item;

        KASSERT(((type & ~NGQF_TYPE) == 0),
            ("%s: incorrect item type: %d", __func__, type));

        item = objcache_get(ng_oc,
            (flags & NG_WAITOK) ? M_WAITOK : M_NOWAIT );

        if (item) {
                item->el_flags = type;
#ifdef  NETGRAPH_DEBUG
                mtx_lock(&ngq_mtx);
                TAILQ_INSERT_TAIL(&ng_itemlist, item, all);
                allocated++;
                mtx_unlock(&ngq_mtx);
#endif
        }

        return (item);
}

/*
 * Release a queue entry
 */
void
ng_free_item(item_p item)
{
        /*
         * If the item still has an apply callback registered, it is
         * being freed too early.
         */
        KASSERT(item->apply == NULL, ("freeing item with registered callback"));

        /*
         * Make sure the reference count has reached zero.
         */
        KASSERT(item->refs == 0, ("freeing item with non-zero refcount"));

        /*
         * The item may hold resources on it's own. We need to free
         * these before we can free the item. What they are depends upon
         * what kind of item it is. it is important that nodes zero
         * out pointers to resources that they remove from the item
         * or we release them again here.
         */
        switch (item->el_flags & NGQF_TYPE) {
        case NGQF_DATA:
                /* If we have an mbuf still attached.. */
                NG_FREE_M(_NGI_M(item));
                break;
        case NGQF_MESG:
                _NGI_RETADDR(item) = 0;
                NG_FREE_MSG(_NGI_MSG(item));
                break;
        case NGQF_FN:
        case NGQF_FN2:
                /* nothing to free really, */
                _NGI_FN(item) = NULL;
                _NGI_ARG1(item) = NULL;
                _NGI_ARG2(item) = 0;
                break;
        }
        /* If we still have a node or hook referenced... */
        _NGI_CLR_NODE(item);
        _NGI_CLR_HOOK(item);

#ifdef  NETGRAPH_DEBUG
        mtx_lock(&ngq_mtx);
        TAILQ_REMOVE(&ng_itemlist, item, all);
        allocated--;
        mtx_unlock(&ngq_mtx);
#endif
        /* Object must be initialized before returning to objcache */
        bzero(item, sizeof(struct ng_item));
        objcache_put(ng_oc, item);
}

/*
 * Change type of the queue entry.
 */
static __inline item_p
ng_realloc_item(item_p item, int type, int flags)
{

        KASSERT((item != NULL), ("%s: can't reallocate NULL", __func__));
        KASSERT(((type & ~NGQF_TYPE) == 0),
            ("%s: incorrect item type: %d", __func__, type));

        item->el_flags = (item->el_flags & ~NGQF_TYPE) | type;

        return (item);
}

__inline apply_p
ng_alloc_apply(void)
{
        return (objcache_get(ng_apply_oc, M_WAITOK));
}

__inline void
ng_free_apply(apply_p apply)
{
        objcache_put(ng_apply_oc, apply);
}

/************************************************************************
                        Module routines
************************************************************************/

/*
 * Handle the loading/unloading of a netgraph node type module
 */
int
ng_mod_event(module_t mod, int event, void *data)
{
        struct ng_type *const type = data;
        int error = 0;

        switch (event) {
        case MOD_LOAD:

                /* Register new netgraph node type */
                if ((error = ng_newtype(type)) != 0) {
                        break;
                }

                /* Call type specific code */
                if (type->mod_event != NULL)
                        if ((error = (*type->mod_event)(mod, event, data))) {
                                TYPELIST_WLOCK();
                                type->refs--;   /* undo it */
                                LIST_REMOVE(type, types);
                                TYPELIST_WUNLOCK();
                        }
                break;

        case MOD_UNLOAD:
                if (type->refs > 1) {           /* make sure no nodes exist! */
                        error = EBUSY;
                } else {
                        if (type->refs == 0) {
                                /* failed load, nothing to undo */
                                break;
                        }
                        if (type->mod_event != NULL) {  /* check with type */
                                error = (*type->mod_event)(mod, event, data);
                                if (error != 0) {       /* type refuses.. */
                                        break;
                                }
                        }
                        TYPELIST_WLOCK();
                        LIST_REMOVE(type, types);
                        TYPELIST_WUNLOCK();
                }
                break;

        default:
                if (type->mod_event != NULL)
                        error = (*type->mod_event)(mod, event, data);
                else
                        error = EOPNOTSUPP;             /* XXX ? */
                break;
        }
        return (error);
}

/*
 * Handle loading and unloading for this code.
 */
static int
ngb_mod_event(module_t mod, int event, void *data)
{
        int i, error = 0;

        switch (event) {
        case MOD_LOAD:
                /* Initialize everything. */
                lwkt_token_init(&ng_typelist_token, "ng typelist");
                lwkt_token_init(&ng_idhash_token, "ng idhash");
                lwkt_token_init(&ng_namehash_token, "ng namehash");
                lwkt_token_init(&ng_topo_token, "ng topology");
#ifdef  NETGRAPH_DEBUG
                mtx_init(&ng_nodelist_mtx, "ng nodelist");
                mtx_init(&ngq_mtx, "ng queue");
#endif
                ng_oc = objcache_create_mbacked(M_NETGRAPH,
                            sizeof(struct ng_item), maxalloc, 0, bzero_ctor,
                            NULL, NULL);
                ng_apply_oc = objcache_create_mbacked(M_NETGRAPH_APPLY,
                            sizeof(struct ng_apply_info), 0, 0, bzero_ctor,
                            NULL, NULL);

                /* We start with small hashes, but they can grow. */
                ng_ID_hash = hashinit(16, M_NETGRAPH_NODE, &ng_ID_hmask);
                ng_name_hash = hashinit(16, M_NETGRAPH_NODE, &ng_name_hmask);

                lwkt_initport_panic(&ng_panic_reply_port);
                for (i = 0; i < ncpus; ++i) {
                        thread_t td;

                        lwkt_create(ngthread, NULL, &td,
                           NULL, 0, i, "netgraph %d", i);
                        ng_msgport[i] = &td->td_msgport;
                }
                break;
        case MOD_UNLOAD:
#if 0
                hashdestroy(V_ng_name_hash, M_NETGRAPH_NODE, V_ng_name_hmask);
                hashdestroy(V_ng_ID_hash, M_NETGRAPH_NODE, V_ng_ID_hmask);

                /* Destroy the lwkt threads too */

                objcache_destroy(ng_apply_oc);
                objcache_destroy(ng_oc);
#endif
                /* You can't unload it because an interface may be using it. */
                error = EBUSY;
                break;
        default:
                error = EOPNOTSUPP;
                break;
        }
        return (error);
}

static moduledata_t netgraph_mod = {
        "netgraph",
        ngb_mod_event,
        (NULL)
};
DECLARE_MODULE(netgraph, netgraph_mod, SI_SUB_NETGRAPH, SI_ORDER_MIDDLE);
SYSCTL_NODE(_net, OID_AUTO, graph, CTLFLAG_RW, 0, "netgraph Family");
SYSCTL_INT(_net_graph, OID_AUTO, abi_version, CTLFLAG_RD, 0, NG_ABI_VERSION,"");
SYSCTL_INT(_net_graph, OID_AUTO, msg_version, CTLFLAG_RD, 0, NG_VERSION, "");

#ifdef  NETGRAPH_DEBUG
void
dumphook (hook_p hook, char *file, int line)
{
        kprintf("hook: name %s, %d refs, Last touched:\n",
                _NG_HOOK_NAME(hook), hook->hk_refs);
        kprintf("       Last active @ %s, line %d\n",
                hook->lastfile, hook->lastline);
        if (line) {
                kprintf(" problem discovered at file %s, line %d\n", file, line);
        }
}

void
dumpnode(node_p node, char *file, int line)
{
        kprintf("node: ID [%x]: type '%s', %d hooks, flags 0x%x, %d refs, %s:\n",
                _NG_NODE_ID(node), node->nd_type->name,
                node->nd_numhooks, node->nd_flags,
                node->nd_refs, node->nd_name);
        kprintf("       Last active @ %s, line %d\n",
                node->lastfile, node->lastline);
        if (line) {
                kprintf(" problem discovered at file %s, line %d\n", file, line);
        }
}

void
dumpitem(item_p item, char *file, int line)
{
        kprintf(" ACTIVE item, last used at %s, line %d",
                item->lastfile, item->lastline);
        switch(item->el_flags & NGQF_TYPE) {
        case NGQF_DATA:
                kprintf(" - [data]\n");
                break;
        case NGQF_MESG:
                kprintf(" - retaddr[%d]:\n", _NGI_RETADDR(item));
                break;
        case NGQF_FN:
                kprintf(" - fn@%p (%p, %p, %p, %d (%x))\n",
                        _NGI_FN(item),
                        _NGI_NODE(item),
                        _NGI_HOOK(item),
                        item->body.fn.fn_arg1,
                        item->body.fn.fn_arg2,
                        item->body.fn.fn_arg2);
                break;
        case NGQF_FN2:
                kprintf(" - fn2@%p (%p, %p, %p, %d (%x))\n",
                        _NGI_FN2(item),
                        _NGI_NODE(item),
                        _NGI_HOOK(item),
                        item->body.fn.fn_arg1,
                        item->body.fn.fn_arg2,
                        item->body.fn.fn_arg2);
                break;
        }
        if (line) {
                kprintf(" problem discovered at file %s, line %d\n", file, line);
                if (_NGI_NODE(item)) {
                        kprintf("node %p ([%x])\n",
                                _NGI_NODE(item), ng_node2ID(_NGI_NODE(item)));
                }
        }
}

static void
ng_dumpitems(void)
{
        item_p item;
        int i = 1;
        TAILQ_FOREACH(item, &ng_itemlist, all) {
                kprintf("[%d] ", i++);
                dumpitem(item, NULL, 0);
        }
}

static void
ng_dumpnodes(void)
{
        node_p node;
        int i = 1;
        mtx_lock(&ng_nodelist_mtx);
        SLIST_FOREACH(node, &ng_allnodes, nd_all) {
                kprintf("[%d] ", i++);
                dumpnode(node, NULL, 0);
        }
        mtx_unlock(&ng_nodelist_mtx);
}

static void
ng_dumphooks(void)
{
        hook_p hook;
        int i = 1;
        mtx_lock(&ng_nodelist_mtx);
        SLIST_FOREACH(hook, &ng_allhooks, hk_all) {
                kprintf("[%d] ", i++);
                dumphook(hook, NULL, 0);
        }
        mtx_unlock(&ng_nodelist_mtx);
}

static int
sysctl_debug_ng_dump_items(SYSCTL_HANDLER_ARGS)
{
        int error;
        int val;

        val = allocated;
        error = sysctl_handle_int(oidp, &val, 0, req);
        if (error != 0 || req->newptr == NULL)
                return (error);
        if (val == 42) {
                ng_dumpitems();
                ng_dumpnodes();
                ng_dumphooks();
        }
        return (0);
}

SYSCTL_PROC(_debug, OID_AUTO, ng_dump_items, CTLTYPE_INT | CTLFLAG_RW,
    0, sizeof(int), sysctl_debug_ng_dump_items, "I", "Number of allocated items");
#endif  /* NETGRAPH_DEBUG */


/***********************************************************************
* Externally useable functions to set up a queue item ready for sending
***********************************************************************/

#ifdef  NETGRAPH_DEBUG
#define ITEM_DEBUG_CHECKS                                               \
        do {                                                            \
                if (NGI_NODE(item) ) {                                  \
                        kprintf("item already has node");               \
                        kdb_enter(KDB_WHY_NETGRAPH, "has node");        \
                        NGI_CLR_NODE(item);                             \
                }                                                       \
                if (NGI_HOOK(item) ) {                                  \
                        kprintf("item already has hook");               \
                        kdb_enter(KDB_WHY_NETGRAPH, "has hook");        \
                        NGI_CLR_HOOK(item);                             \
                }                                                       \
        } while (0)
#else
#define ITEM_DEBUG_CHECKS
#endif

/*
 * Put mbuf into the item.
 * Hook and node references will be removed when the item is dequeued.
 * (or equivalent)
 * (XXX) Unsafe because no reference held by peer on remote node.
 * remote node might go away in this timescale.
 * We know the hooks can't go away because that would require getting
 * a writer item on both nodes and we must have at least a  reader
 * here to be able to do this.
 * Note that the hook loaded is the REMOTE hook.
 *
 * This is possibly in the critical path for new data.
 */
item_p
ng_package_data(struct mbuf *m, int flags)
{
        item_p item;

        if ((item = ng_alloc_item(NGQF_DATA, flags)) == NULL) {
                NG_FREE_M(m);
                return (NULL);
        }
        ITEM_DEBUG_CHECKS;
        item->el_flags |= NGQF_READER;
        NGI_M(item) = m;
        return (item);
}

/*
 * Allocate a queue item and put items into it..
 * Evaluate the address as this will be needed to queue it and
 * to work out what some of the fields should be.
 * Hook and node references will be removed when the item is dequeued.
 * (or equivalent)
 */
item_p
ng_package_msg(struct ng_mesg *msg, int flags)
{
        item_p item;

        if ((item = ng_alloc_item(NGQF_MESG, flags)) == NULL) {
                NG_FREE_MSG(msg);
                return (NULL);
        }
        ITEM_DEBUG_CHECKS;
        /* Messages items count as writers unless explicitly exempted. */
        if (msg->header.cmd & NGM_READONLY)
                item->el_flags |= NGQF_READER;
        else
                item->el_flags |= NGQF_WRITER;
        /*
         * Set the current lasthook into the queue item
         */
        NGI_MSG(item) = msg;
        NGI_RETADDR(item) = 0;
        return (item);
}



#define SET_RETADDR(item, here, retaddr)                                \
        do {    /* Data or fn items don't have retaddrs */              \
                if ((item->el_flags & NGQF_TYPE) == NGQF_MESG) {        \
                        if (retaddr) {                                  \
                                NGI_RETADDR(item) = retaddr;            \
                        } else {                                        \
                                /*                                      \
                                 * The old return address should be ok. \
                                 * If there isn't one, use the address  \
                                 * here.                                \
                                 */                                     \
                                if (NGI_RETADDR(item) == 0) {           \
                                        NGI_RETADDR(item)               \
                                                = ng_node2ID(here);     \
                                }                                       \
                        }                                               \
                }                                                       \
        } while (0)

int
ng_address_hook(node_p here, item_p item, hook_p hook, ng_ID_t retaddr)
{
        hook_p peer;
        node_p peernode;
        ITEM_DEBUG_CHECKS;
        /*
         * Quick sanity check..
         * Since a hook holds a reference on it's node, once we know
         * that the peer is still connected (even if invalid,) we know
         * that the peer node is present, though maybe invalid.
         */
        if ((hook == NULL) ||
            NG_HOOK_NOT_VALID(hook) ||
            NG_HOOK_NOT_VALID(peer = NG_HOOK_PEER(hook)) ||
            NG_NODE_NOT_VALID(peernode = NG_PEER_NODE(hook))) {
                NG_FREE_ITEM(item);
                TRAP_ERROR();
                return (ENETDOWN);
        }

        /*
         * Transfer our interest to the other (peer) end.
         */
        NG_HOOK_REF(peer);
        NG_NODE_REF(peernode);
        NGI_SET_HOOK(item, peer);
        NGI_SET_NODE(item, peernode);
        SET_RETADDR(item, here, retaddr);
        return (0);
}

int
ng_address_path(node_p here, item_p item, char *address, ng_ID_t retaddr)
{
        node_p  dest = NULL;
        hook_p  hook = NULL;
        int     error;

        ITEM_DEBUG_CHECKS;
        /*
         * Note that ng_path2noderef increments the reference count
         * on the node for us if it finds one. So we don't have to.
         */
        error = ng_path2noderef(here, address, &dest, &hook);
        if (error) {
                NG_FREE_ITEM(item);
                return (error);
        }
        NGI_SET_NODE(item, dest);
        if ( hook) {
                NG_HOOK_REF(hook);      /* don't let it go while on the queue */
                NGI_SET_HOOK(item, hook);
        }
        SET_RETADDR(item, here, retaddr);
        return (0);
}

int
ng_address_ID(node_p here, item_p item, ng_ID_t ID, ng_ID_t retaddr)
{
        node_p dest;

        ITEM_DEBUG_CHECKS;
        /*
         * Find the target node.
         */
        dest = ng_ID2noderef(ID); /* GETS REFERENCE! */
        if (dest == NULL) {
                NG_FREE_ITEM(item);
                TRAP_ERROR();
                return(EINVAL);
        }
        /* Fill out the contents */
        NGI_SET_NODE(item, dest);
        NGI_CLR_HOOK(item);
        SET_RETADDR(item, here, retaddr);
        return (0);
}

/*
 * special case to send a message to self (e.g. destroy node)
 * Possibly indicate an arrival hook too.
 * Useful for removing that hook :-)
 */
item_p
ng_package_msg_self(node_p here, hook_p hook, struct ng_mesg *msg)
{
        item_p item;

        /*
         * Find the target node.
         * If there is a HOOK argument, then use that in preference
         * to the address.
         */
        if ((item = ng_alloc_item(NGQF_MESG, NG_NOFLAGS)) == NULL) {
                NG_FREE_MSG(msg);
                return (NULL);
        }

        /* Fill out the contents */
        item->el_flags |= NGQF_WRITER;
        NG_NODE_REF(here);
        NGI_SET_NODE(item, here);
        if (hook) {
                NG_HOOK_REF(hook);
                NGI_SET_HOOK(item, hook);
        }
        NGI_MSG(item) = msg;
        NGI_RETADDR(item) = ng_node2ID(here);
        return (item);
}

/*
 * Send ng_item_fn function call to the specified node.
 */

int
ng_send_fn(node_p node, hook_p hook, ng_item_fn *fn, void * arg1, int arg2)
{
        return ng_send_fn1(node, hook, fn, arg1, arg2, NG_NOFLAGS);
}

int
ng_send_fn1(node_p node, hook_p hook, ng_item_fn *fn, void * arg1, int arg2,
        int flags)
{
        item_p item;

        if ((item = ng_alloc_item(NGQF_FN, flags)) == NULL) {
                return (ENOMEM);
        }
        item->el_flags |= NGQF_WRITER;
        NG_NODE_REF(node); /* and one for the item */
        NGI_SET_NODE(item, node);
        if (hook) {
                NG_HOOK_REF(hook);
                NGI_SET_HOOK(item, hook);
        }
        NGI_FN(item) = fn;
        NGI_ARG1(item) = arg1;
        NGI_ARG2(item) = arg2;
        return(ng_snd_item(item, flags));
}

/*
 * Send ng_item_fn2 function call to the specified node.
 *
 * If NG_REUSE_ITEM flag is set, no new item will be allocated,
 * pitem will be used instead.
 */
int
ng_send_fn2(node_p node, hook_p hook, item_p pitem, ng_item_fn2 *fn, void *arg1,
        int arg2, int flags)
{
        item_p item;

        KASSERT((pitem != NULL || (flags & NG_REUSE_ITEM) == 0),
            ("%s: NG_REUSE_ITEM but no pitem", __func__));

        /*
         * Allocate a new item if no supplied or
         * if we can't use supplied one.
         */
        if (pitem == NULL || (flags & NG_REUSE_ITEM) == 0) {
                if ((item = ng_alloc_item(NGQF_FN2, flags)) == NULL)
                        return (ENOMEM);
        } else {
                if ((item = ng_realloc_item(pitem, NGQF_FN2, flags)) == NULL)
                        return (ENOMEM);
        }

        item->el_flags = (item->el_flags & ~NGQF_RW) | NGQF_WRITER;
        NG_NODE_REF(node); /* and one for the item */
        NGI_SET_NODE(item, node);
        if (hook) {
                NG_HOOK_REF(hook);
                NGI_SET_HOOK(item, hook);
        }
        NGI_FN2(item) = fn;
        NGI_ARG1(item) = arg1;
        NGI_ARG2(item) = arg2;
        return(ng_snd_item(item, flags));
}

/*
 * Official timeout routines for Netgraph nodes.
 */
static void
ng_callout_trampoline(void *arg)
{
        item_p item = arg;

        ng_snd_item(item, 0);
}


int
ng_callout(struct callout *c, node_p node, hook_p hook, int ticks,
    ng_item_fn *fn, void * arg1, int arg2)
{
        item_p item, oitem;

        if ((item = ng_alloc_item(NGQF_FN, NG_NOFLAGS)) == NULL)
                return (ENOMEM);

        item->el_flags |= NGQF_WRITER;
        NG_NODE_REF(node);              /* and one for the item */
        NGI_SET_NODE(item, node);
        if (hook) {
                NG_HOOK_REF(hook);
                NGI_SET_HOOK(item, hook);
        }
        NGI_FN(item) = fn;
        NGI_ARG1(item) = arg1;
        NGI_ARG2(item) = arg2;
        oitem = callout_arg(c);
        callout_reset(c, ticks, &ng_callout_trampoline, item);
        return (0);
}

/* A special modified version of untimeout() */
int
ng_uncallout(struct callout *c, node_p node)
{
        item_p item;
        int rval;

        KASSERT(c != NULL, ("ng_uncallout: NULL callout"));
        KASSERT(node != NULL, ("ng_uncallout: NULL node"));

        rval = callout_stop(c);
        item = callout_arg(c);
        /* Do an extra check */
        if ((rval > 0) && (callout_func(c) == &ng_callout_trampoline) &&
            (NGI_NODE(item) == node)) {
                /*
                 * We successfully removed it from the queue before it ran
                 * So now we need to unreference everything that was
                 * given extra references. (NG_FREE_ITEM does this).
                 */
                NG_FREE_ITEM(item);
        }
        callout_set_arg(c, NULL);

        return (rval);
}

/*
 * Set the address, if none given, give the node here.
 */
void
ng_replace_retaddr(node_p here, item_p item, ng_ID_t retaddr)
{
        if (retaddr) {
                NGI_RETADDR(item) = retaddr;
        } else {
                /*
                 * The old return address should be ok.
                 * If there isn't one, use the address here.
                 */
                NGI_RETADDR(item) = ng_node2ID(here);
        }
}

static boolean_t
bzero_ctor(void *obj, void *private, int ocflags)
{
        struct ng_item *i = obj;

        bzero(i, sizeof(struct ng_item));
        return(TRUE);
}

#define TESTING
#ifdef TESTING
/* just test all the macros */
void
ng_macro_test(item_p item);
void
ng_macro_test(item_p item)
{
        node_p node = NULL;
        hook_p hook = NULL;
        struct mbuf *m;
        struct ng_mesg *msg;
        ng_ID_t retaddr;
        int     error;

        NGI_GET_M(item, m);
        NGI_GET_MSG(item, msg);
        retaddr = NGI_RETADDR(item);
        NG_SEND_DATA(error, hook, m, NULL);
        NG_SEND_DATA_ONLY(error, hook, m);
        NG_FWD_NEW_DATA(error, item, hook, m);
        NG_FWD_ITEM_HOOK(error, item, hook);
        NG_SEND_MSG_HOOK(error, node, msg, hook, retaddr);
        NG_SEND_MSG_ID(error, node, msg, retaddr, retaddr);
        NG_SEND_MSG_PATH(error, node, msg, ".:", retaddr);
        NG_FWD_MSG_HOOK(error, node, item, hook, retaddr);
}
#endif /* TESTING */