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ng_base.c

/*
 * ng_base.c
 */

/*-
 * 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 1.135.2.2 2007/11/21 12:11:45 glebius 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/kdb.h>
#include <sys/kernel.h>
#include <sys/ktr.h>
#include <sys/limits.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/queue.h>
#include <sys/sysctl.h>
#include <sys/syslog.h>
#include <sys/refcount.h>

#include <net/netisr.h>

#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_parse.h>

MODULE_VERSION(netgraph, NG_ABI_VERSION);

/* List of all active nodes */
static LIST_HEAD(, ng_node) ng_nodelist;
static struct mtx ng_nodelist_mtx;

/* Mutex to protect topology events. */
static struct mtx ng_topo_mtx;

#ifdef      NETGRAPH_DEBUG
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 neccesary 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,
      1,    /* refs */
      0,    /* numhooks */
      NULL, /* private */
      0,    /* ID */
      LIST_HEAD_INITIALIZER(ng_deadnode.hooks),
      {},   /* all_nodes list entry */
      {},   /* id hashtable list entry */
      {},   /* workqueue entry */
      {     0,
            {}, /* should never use! (should hang) */
            NULL,
            &ng_deadnode.nd_input_queue.queue,
            &ng_deadnode
      },
#ifdef      NETGRAPH_DEBUG
      ND_MAGIC,
      __FILE__,
      __LINE__,
      {NULL}
#endif      /* NETGRAPH_DEBUG */
};

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

/*
 * END DEAD STRUCTURES
 */
/* List nodes with unallocated work */
static TAILQ_HEAD(, ng_node) ng_worklist = TAILQ_HEAD_INITIALIZER(ng_worklist);
static struct mtx ng_worklist_mtx;   /* MUST LOCK NODE FIRST */

/* List of installed types */
static LIST_HEAD(, ng_type) ng_typelist;
static struct mtx ng_typelist_mtx;

/* Hash related definitions */
/* XXX Don't need to initialise them because it's a LIST */
#define NG_ID_HASH_SIZE 32 /* most systems wont need even this many */
static LIST_HEAD(, ng_node) ng_ID_hash[NG_ID_HASH_SIZE];
static struct mtx ng_idhash_mtx;
/* Method to find a node.. used twice so do it here */
#define NG_IDHASH_FN(ID) ((ID) % (NG_ID_HASH_SIZE))
#define NG_IDHASH_FIND(ID, node)                            \
      do {                                            \
            mtx_assert(&ng_idhash_mtx, MA_OWNED);                 \
            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)


/* 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 ng_worklist_remove(node_p node);
static void ngintr(void);
static int  ng_apply_item(node_p node, item_p item, int rw);
static void ng_flush_input_queue(struct ng_queue * ngq);
static void ng_setisr(node_p node);
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);

/* 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_ITEM, "netgraph_item", "netgraph item structures");
MALLOC_DEFINE(M_NETGRAPH_MSG, "netgraph_msg", "netgraph name storage");

/* Should not be visible outside this file */

#define _NG_ALLOC_HOOK(hook) \
      MALLOC(hook, hook_p, sizeof(*hook), M_NETGRAPH_HOOK, M_NOWAIT | M_ZERO)
#define _NG_ALLOC_NODE(node) \
      MALLOC(node, node_p, sizeof(*node), M_NETGRAPH_NODE, M_NOWAIT | M_ZERO)

#define     NG_QUEUE_LOCK_INIT(n)               \
      mtx_init(&(n)->q_mtx, "ng_node", NULL, MTX_DEF)
#define     NG_QUEUE_LOCK(n)              \
      mtx_lock(&(n)->q_mtx)
#define     NG_QUEUE_UNLOCK(n)                  \
      mtx_unlock(&(n)->q_mtx)
#define     NG_WORKLIST_LOCK_INIT()             \
      mtx_init(&ng_worklist_mtx, "ng_worklist", NULL, MTX_DEF)
#define     NG_WORKLIST_LOCK()                  \
      mtx_lock(&ng_worklist_mtx)
#define     NG_WORKLIST_UNLOCK()                \
      mtx_unlock(&ng_worklist_mtx)

#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 { FREE((hook), M_NETGRAPH_HOOK); } while (0)
#define NG_FREE_NODE(node) do { FREE((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
};

/* 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
};

/* 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
};

DEFINE_PARSE_STRUCT_TYPE(typelist, TYPELIST, (&ng_generic_nodeinfoarray_type));
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++;

      NG_QUEUE_LOCK_INIT(&node->nd_input_queue);
      node->nd_input_queue.queue = NULL;
      node->nd_input_queue.last = &node->nd_input_queue.queue;
      node->nd_input_queue.q_flags = 0;
      node->nd_input_queue.q_node = node;

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

      /* Link us into the node linked list */
      mtx_lock(&ng_nodelist_mtx);
      LIST_INSERT_HEAD(&ng_nodelist, node, nd_nodes);
      mtx_unlock(&ng_nodelist_mtx);


      /* get an ID and put us in the hash chain */
      mtx_lock(&ng_idhash_mtx);
      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;
            }
      }
      LIST_INSERT_HEAD(&ng_ID_hash[NG_IDHASH_FN(node->nd_ID)],
                                          node, nd_idnodes);
      mtx_unlock(&ng_idhash_mtx);

      /* 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. It also means
 * that we should not be on the work queue, but we check anyhow.
 *
 * 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) {
            printf ("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);

      /*
       * Drain the input queue forceably.
       * it has no hooks so what's it going to do, bleed on someone?
       * Theoretically we came here from a queue entry that was added
       * Just before the queue was closed, so it should be empty anyway.
       * Also removes us from worklist if needed.
       */
      ng_flush_input_queue(&node->nd_input_queue);

      /* 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.
 */
int
ng_unref_node(node_p node)
{
      int v;

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

      do {
            v = node->nd_refs - 1;
      } while (! atomic_cmpset_int(&node->nd_refs, v + 1, v));

      if (v == 0) { /* we were the last */

            mtx_lock(&ng_nodelist_mtx);
            node->nd_type->refs--; /* XXX maybe should get types lock? */
            LIST_REMOVE(node, nd_nodes);
            mtx_unlock(&ng_nodelist_mtx);

            mtx_lock(&ng_idhash_mtx);
            LIST_REMOVE(node, nd_idnodes);
            mtx_unlock(&ng_idhash_mtx);

            mtx_destroy(&node->nd_input_queue.q_mtx);
            NG_FREE_NODE(node);
      }
      return (v);
}

/************************************************************************
                  Node ID handling
************************************************************************/
static node_p
ng_ID2noderef(ng_ID_t ID)
{
      node_p node;
      mtx_lock(&ng_idhash_mtx);
      NG_IDHASH_FIND(ID, node);
      if(node)
            NG_NODE_REF(node);
      mtx_unlock(&ng_idhash_mtx);
      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. Once assigned, the name cannot be changed.
 */
int
ng_name_node(node_p node, const char *name)
{
      int i;
      node_p node2;

      /* 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);
      }

      /* Check the name isn't already being used */
      if ((node2 = ng_name2noderef(node, name)) != NULL) {
            NG_NODE_UNREF(node2);
            TRAP_ERROR();
            return (EADDRINUSE);
      }

      /* copy it */
      strlcpy(NG_NODE_NAME(node), name, NG_NODESIZ);

      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;

      /* "." 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 */
      mtx_lock(&ng_nodelist_mtx);
      LIST_FOREACH(node, &ng_nodelist, nd_nodes) {
            if (NG_NODE_IS_VALID(node)
            && NG_NODE_HAS_NAME(node)
            && (strcmp(NG_NODE_NAME(node), name) == 0)) {
                  break;
            }
      }
      if (node)
            NG_NODE_REF(node);
      mtx_unlock(&ng_nodelist_mtx);
      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.
 * IF we allow name changing this may be more resurrected.
 */
void
ng_unname(node_p node)
{
}

/************************************************************************
                  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;
      }
      do {
            v = hook->hk_refs;
      } while (! atomic_cmpset_int(&hook->hk_refs, v, v - 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)));
                  hook->hk_node = NULL;
            }
            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 */
            printf("ng_destroy_hook called on deadhook\n");
            return;
      }

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

      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.
                   */
                  mtx_unlock(&ng_topo_mtx);
            } else {
                  mtx_unlock(&ng_topo_mtx);
                  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
            mtx_unlock(&ng_topo_mtx);

      mtx_assert(&ng_topo_mtx, MA_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) {
                  printf("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 */
      mtx_lock(&ng_typelist_mtx);
      LIST_INSERT_HEAD(&ng_typelist, tp, types);
      tp->refs = 1;     /* first ref is linked list */
      mtx_unlock(&ng_typelist_mtx);
      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 */
      mtx_lock(&ng_typelist_mtx);
      LIST_REMOVE(tp, types);
      mtx_unlock(&ng_typelist_mtx);
      return (0);
}

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

      mtx_lock(&ng_typelist_mtx);
      LIST_FOREACH(type, &ng_typelist, types) {
            if (strcmp(type->name, typename) == 0)
                  break;
      }
      mtx_unlock(&ng_typelist_mtx);
      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 */
                  printf("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 */
            printf("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 */
                  printf("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 */
                  printf("failed in ng_con_part2(A)\n");
                  ERROUT(error);
            }
      }

      /*
       * Acquire topo mutex to avoid race with ng_destroy_hook().
       */
      mtx_lock(&ng_topo_mtx);
      peer = hook->hk_peer;
      if (peer == &ng_deadhook) {
            mtx_unlock(&ng_topo_mtx);
            printf("failed in ng_con_part2(B)\n");
            ng_destroy_hook(hook);
            ERROUT(ENOENT);
      }
      mtx_unlock(&ng_topo_mtx);

      if ((error = ng_send_fn2(peer->hk_node, peer, item, &ng_con_part3,
          NULL, 0, NG_REUSE_ITEM))) {
            printf("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))) {
            printf("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
                  printf("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);
}

/***************************************************************\
* Input queue handling.
* All activities are submitted to the node via the input queue
* which implements a multiple-reader/single-writer gate.
* Items which cannot be handled immediately are queued.
*
* read-write queue locking inline functions                 *
\***************************************************************/

static __inline item_p ng_dequeue(struct ng_queue * ngq, int *rw);
static __inline item_p ng_acquire_read(struct ng_queue * ngq,
                              item_p  item);
static __inline item_p ng_acquire_write(struct ng_queue * ngq,
                              item_p  item);
static __inline void    ng_leave_read(struct ng_queue * ngq);
static __inline void    ng_leave_write(struct ng_queue * ngq);
static __inline void    ng_queue_rw(struct ng_queue * ngq,
                              item_p  item, int rw);

/*
 * Definition of the bits fields in the ng_queue flag word.
 * Defined here rather than in netgraph.h because no-one should fiddle
 * with them.
 *
 * The ordering here may be important! don't shuffle these.
 */
/*-
 Safety Barrier--------+ (adjustable to suit taste) (not used yet)
                       |
                       V
+-------+-------+-------+-------+-------+-------+-------+-------+
  | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
  | |A|c|t|i|v|e| |R|e|a|d|e|r| |C|o|u|n|t| | | | | | | | | |P|A|
  | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |O|W|
+-------+-------+-------+-------+-------+-------+-------+-------+
  \___________________________ ____________________________/ | |
                            V                                | |
                  [active reader count]                      | |
                                                             | |
            Operation Pending -------------------------------+ |
                                                               |
          Active Writer ---------------------------------------+


*/
#define WRITER_ACTIVE   0x00000001
#define OP_PENDING      0x00000002
#define READER_INCREMENT 0x00000004
#define READER_MASK     0xfffffffc  /* Not valid if WRITER_ACTIVE is set */
#define SAFETY_BARRIER  0x00100000  /* 128K items queued should be enough */

/* Defines of more elaborate states on the queue */
/* Mask of bits a new read cares about */
#define NGQ_RMASK (WRITER_ACTIVE|OP_PENDING)

/* Mask of bits a new write cares about */
#define NGQ_WMASK (NGQ_RMASK|READER_MASK)

/* Test to decide if there is something on the queue. */
#define QUEUE_ACTIVE(QP) ((QP)->q_flags & OP_PENDING)

/* How to decide what the next queued item is. */
#define HEAD_IS_READER(QP)  NGI_QUEUED_READER((QP)->queue)
#define HEAD_IS_WRITER(QP)  NGI_QUEUED_WRITER((QP)->queue) /* notused */

/* Read the status to decide if the next item on the queue can now run. */
#define QUEUED_READER_CAN_PROCEED(QP)                 \
            (((QP)->q_flags & (NGQ_RMASK & ~OP_PENDING)) == 0)
#define QUEUED_WRITER_CAN_PROCEED(QP)                 \
            (((QP)->q_flags & (NGQ_WMASK & ~OP_PENDING)) == 0)

/* Is there a chance of getting ANY work off the queue? */
#define NEXT_QUEUED_ITEM_CAN_PROCEED(QP)                    \
      (QUEUE_ACTIVE(QP) &&                                  \
      ((HEAD_IS_READER(QP)) ? QUEUED_READER_CAN_PROCEED(QP) :           \
                        QUEUED_WRITER_CAN_PROCEED(QP)))


#define NGQRW_R 0
#define NGQRW_W 1

/*
 * Taking into account the current state of the queue and node, possibly take
 * the next entry off the queue and return it. Return NULL if there was
 * nothing we could return, either because there really was nothing there, or
 * because the node was in a state where it cannot yet process the next item
 * on the queue.
 *
 * This MUST MUST MUST be called with the mutex held.
 */
static __inline item_p
ng_dequeue(struct ng_queue *ngq, int *rw)
{
      item_p item;
      u_int       add_arg;

      mtx_assert(&ngq->q_mtx, MA_OWNED);
      /*
       * If there is nothing queued, then just return.
       * No point in continuing.
       * XXXGL: assert this?
       */
      if (!QUEUE_ACTIVE(ngq)) {
            CTR4(KTR_NET, "%20s: node [%x] (%p) queue empty; "
                "queue flags 0x%lx", __func__,
                ngq->q_node->nd_ID, ngq->q_node, ngq->q_flags);
            return (NULL);
      }

      /*
       * From here, we can assume there is a head item.
       * We need to find out what it is and if it can be dequeued, given
       * the current state of the node.
       */
      if (HEAD_IS_READER(ngq)) {
            if (!QUEUED_READER_CAN_PROCEED(ngq)) {
                  /*
                   * It's a reader but we can't use it.
                   * We are stalled so make sure we don't
                   * get called again until something changes.
                   */
                  ng_worklist_remove(ngq->q_node);
                  CTR4(KTR_NET, "%20s: node [%x] (%p) queued reader "
                      "can't proceed; queue flags 0x%lx", __func__,
                      ngq->q_node->nd_ID, ngq->q_node, ngq->q_flags);
                  return (NULL);
            }
            /*
             * Head of queue is a reader and we have no write active.
             * We don't care how many readers are already active.
             * Add the correct increment for the reader count.
             */
            add_arg = READER_INCREMENT;
            *rw = NGQRW_R;
      } else if (QUEUED_WRITER_CAN_PROCEED(ngq)) {
            /*
             * There is a pending write, no readers and no active writer.
             * This means we can go ahead with the pending writer. Note
             * the fact that we now have a writer, ready for when we take
             * it off the queue.
             *
             * We don't need to worry about a possible collision with the
             * fasttrack reader.
             *
             * The fasttrack thread may take a long time to discover that we
             * are running so we would have an inconsistent state in the
             * flags for a while. Since we ignore the reader count
             * entirely when the WRITER_ACTIVE flag is set, this should
             * not matter (in fact it is defined that way). If it tests
             * the flag before this operation, the OP_PENDING flag
             * will make it fail, and if it tests it later, the
             * WRITER_ACTIVE flag will do the same. If it is SO slow that
             * we have actually completed the operation, and neither flag
             * is set by the time that it tests the flags, then it is
             * actually ok for it to continue. If it completes and we've
             * finished and the read pending is set it still fails.
             *
             * So we can just ignore it,  as long as we can ensure that the
             * transition from WRITE_PENDING state to the WRITER_ACTIVE
             * state is atomic.
             *
             * After failing, first it will be held back by the mutex, then
             * when it can proceed, it will queue its request, then it
             * would arrive at this function. Usually it will have to
             * leave empty handed because the ACTIVE WRITER bit will be
             * set.
             *
             * Adjust the flags for the new active writer.
             */
            add_arg = WRITER_ACTIVE;
            *rw = NGQRW_W;
            /*
             * We want to write "active writer, no readers " Now go make
             * it true. In fact there may be a number in the readers
             * count but we know it is not true and will be fixed soon.
             * We will fix the flags for the next pending entry in a
             * moment.
             */
      } else {
            /*
             * We can't dequeue anything.. return and say so. Probably we
             * have a write pending and the readers count is non zero. If
             * we got here because a reader hit us just at the wrong
             * moment with the fasttrack code, and put us in a strange
             * state, then it will be coming through in just a moment,
             * (just as soon as we release the mutex) and keep things
             * moving.
             * Make sure we remove ourselves from the work queue. It
             * would be a waste of effort to do all this again.
             */
            ng_worklist_remove(ngq->q_node);
            CTR4(KTR_NET, "%20s: node [%x] (%p) can't dequeue anything; "
                "queue flags 0x%lx", __func__,
                ngq->q_node->nd_ID, ngq->q_node, ngq->q_flags);
            return (NULL);
      }

      /*
       * Now we dequeue the request (whatever it may be) and correct the
       * pending flags and the next and last pointers.
       */
      item = ngq->queue;
      ngq->queue = item->el_next;
      CTR6(KTR_NET, "%20s: node [%x] (%p) dequeued item %p with flags 0x%lx; "
          "queue flags 0x%lx", __func__,
          ngq->q_node->nd_ID,ngq->q_node, item, item->el_flags, ngq->q_flags);
      if (ngq->last == &(item->el_next)) {
            /*
             * that was the last entry in the queue so set the 'last
             * pointer up correctly and make sure the pending flag is
             * clear.
             */
            add_arg += -OP_PENDING;
            ngq->last = &(ngq->queue);
            /*
             * Whatever flag was set will be cleared and
             * the new acive field will be set by the add as well,
             * so we don't need to change add_arg.
             * But we know we don't need to be on the work list.
             */
            atomic_add_long(&ngq->q_flags, add_arg);
            ng_worklist_remove(ngq->q_node);
      } else {
            /*
             * Since there is still something on the queue
             * we don't need to change the PENDING flag.
             */
            atomic_add_long(&ngq->q_flags, add_arg);
            /*
             * If we see more doable work, make sure we are
             * on the work queue.
             */
            if (NEXT_QUEUED_ITEM_CAN_PROCEED(ngq)) {
                  ng_setisr(ngq->q_node);
            }
      }
      CTR6(KTR_NET, "%20s: node [%x] (%p) returning item %p as %s; "
          "queue flags 0x%lx", __func__,
          ngq->q_node->nd_ID, ngq->q_node, item, *rw ? "WRITER" : "READER" ,
          ngq->q_flags);
      return (item);
}

/*
 * Queue a packet to be picked up by someone else.
 * We really don't care who, but we can't or don't want to hang around
 * to process it ourselves. We are probably an interrupt routine..
 * If the queue could be run, flag the netisr handler to start.
 */
static __inline void
ng_queue_rw(struct ng_queue * ngq, item_p  item, int rw)
{
      mtx_assert(&ngq->q_mtx, MA_OWNED);

      if (rw == NGQRW_W)
            NGI_SET_WRITER(item);
      else
            NGI_SET_READER(item);
      item->el_next = NULL;   /* maybe not needed */
      *ngq->last = item;
      CTR5(KTR_NET, "%20s: node [%x] (%p) queued item %p as %s", __func__,
          ngq->q_node->nd_ID, ngq->q_node, item, rw ? "WRITER" : "READER" );
      /*
       * If it was the first item in the queue then we need to
       * set the last pointer and the type flags.
       */
      if (ngq->last == &(ngq->queue)) {
            atomic_add_long(&ngq->q_flags, OP_PENDING);
            CTR3(KTR_NET, "%20s: node [%x] (%p) set OP_PENDING", __func__,
                ngq->q_node->nd_ID, ngq->q_node);
      }

      ngq->last = &(item->el_next);
      /*
       * We can take the worklist lock with the node locked
       * BUT NOT THE REVERSE!
       */
      if (NEXT_QUEUED_ITEM_CAN_PROCEED(ngq))
            ng_setisr(ngq->q_node);
}


/*
 * This function 'cheats' in that it first tries to 'grab' the use of the
 * node, without going through the mutex. We can do this becasue of the
 * semantics of the lock. The semantics include a clause that says that the
 * value of the readers count is invalid if the WRITER_ACTIVE flag is set. It
 * also says that the WRITER_ACTIVE flag cannot be set if the readers count
 * is not zero. Note that this talks about what is valid to SET the
 * WRITER_ACTIVE flag, because from the moment it is set, the value if the
 * reader count is immaterial, and not valid. The two 'pending' flags have a
 * similar effect, in that If they are orthogonal to the two active fields in
 * how they are set, but if either is set, the attempted 'grab' need to be
 * backed out because there is earlier work, and we maintain ordering in the
 * queue. The result of this is that the reader request can try obtain use of
 * the node with only a single atomic addition, and without any of the mutex
 * overhead. If this fails the operation degenerates to the same as for other
 * cases.
 *
 */
static __inline item_p
ng_acquire_read(struct ng_queue *ngq, item_p item)
{
      KASSERT(ngq != &ng_deadnode.nd_input_queue,
          ("%s: working on deadnode", __func__));

      /* ######### Hack alert ######### */
      atomic_add_long(&ngq->q_flags, READER_INCREMENT);
      if ((ngq->q_flags & NGQ_RMASK) == 0) {
            /* Successfully grabbed node */
            CTR4(KTR_NET, "%20s: node [%x] (%p) fast acquired item %p",
                __func__, ngq->q_node->nd_ID, ngq->q_node, item);
            return (item);
      }
      /* undo the damage if we didn't succeed */
      atomic_subtract_long(&ngq->q_flags, READER_INCREMENT);

      /* ######### End Hack alert ######### */
      NG_QUEUE_LOCK(ngq);
      /*
       * Try again. Another processor (or interrupt for that matter) may
       * have removed the last queued item that was stopping us from
       * running, between the previous test, and the moment that we took
       * the mutex. (Or maybe a writer completed.)
       * Even if another fast-track reader hits during this period
       * we don't care as multiple readers is OK.
       */
      if ((ngq->q_flags & NGQ_RMASK) == 0) {
            atomic_add_long(&ngq->q_flags, READER_INCREMENT);
            NG_QUEUE_UNLOCK(ngq);
            CTR4(KTR_NET, "%20s: node [%x] (%p) slow acquired item %p",
                __func__, ngq->q_node->nd_ID, ngq->q_node, item);
            return (item);
      }

      /*
       * and queue the request for later.
       */
      ng_queue_rw(ngq, item, NGQRW_R);
      NG_QUEUE_UNLOCK(ngq);

      return (NULL);
}

static __inline item_p
ng_acquire_write(struct ng_queue *ngq, item_p item)
{
      KASSERT(ngq != &ng_deadnode.nd_input_queue,
          ("%s: working on deadnode", __func__));

restart:
      NG_QUEUE_LOCK(ngq);
      /*
       * If there are no readers, no writer, and no pending packets, then
       * we can just go ahead. In all other situations we need to queue the
       * request
       */
      if ((ngq->q_flags & NGQ_WMASK) == 0) {
            /* collision could happen *HERE* */
            atomic_add_long(&ngq->q_flags, WRITER_ACTIVE);
            NG_QUEUE_UNLOCK(ngq);
            if (ngq->q_flags & READER_MASK) {
                  /* Collision with fast-track reader */
                  atomic_subtract_long(&ngq->q_flags, WRITER_ACTIVE);
                  goto restart;
            }
            CTR4(KTR_NET, "%20s: node [%x] (%p) acquired item %p",
                __func__, ngq->q_node->nd_ID, ngq->q_node, item);
            return (item);
      }

      /*
       * and queue the request for later.
       */
      ng_queue_rw(ngq, item, NGQRW_W);
      NG_QUEUE_UNLOCK(ngq);

      return (NULL);
}

#if 0
static __inline item_p
ng_upgrade_write(struct ng_queue *ngq, item_p item)
{
      KASSERT(ngq != &ng_deadnode.nd_input_queue,
          ("%s: working on deadnode", __func__));

      NGI_SET_WRITER(item);

      mtx_lock_spin(&(ngq->q_mtx));

      /*
       * There will never be no readers as we are there ourselves.
       * Set the WRITER_ACTIVE flags ASAP to block out fast track readers.
       * The caller we are running from will call ng_leave_read()
       * soon, so we must account for that. We must leave again with the
       * READER lock. If we find other readers, then
       * queue the request for later. However "later" may be rignt now
       * if there are no readers. We don't really care if there are queued
       * items as we will bypass them anyhow.
       */
      atomic_add_long(&ngq->q_flags, WRITER_ACTIVE - READER_INCREMENT);
      if (ngq->q_flags & (NGQ_WMASK & ~OP_PENDING) == WRITER_ACTIVE) {
            mtx_unlock_spin(&(ngq->q_mtx));
            
            /* It's just us, act on the item. */
            /* will NOT drop writer lock when done */
            ng_apply_item(node, item, 0);

            /*
             * Having acted on the item, atomically 
             * down grade back to READER and finish up
             */
            atomic_add_long(&ngq->q_flags,
                READER_INCREMENT - WRITER_ACTIVE);

            /* Our caller will call ng_leave_read() */
            return;
      }
      /*
       * It's not just us active, so queue us AT THE HEAD.
       * "Why?" I hear you ask.
       * Put us at the head of the queue as we've already been
       * through it once. If there is nothing else waiting,
       * set the correct flags.
       */
      if ((item->el_next = ngq->queue) == NULL) {
            /*
             * Set up the "last" pointer.
             * We are the only (and thus last) item
             */
            ngq->last = &(item->el_next);

            /* We've gone from, 0 to 1 item in the queue */
            atomic_add_long(&ngq->q_flags, OP_PENDING);

            CTR3(KTR_NET, "%20s: node [%x] (%p) set OP_PENDING", __func__,
                ngq->q_node->nd_ID, ngq->q_node);
      };
      ngq->queue = item;
      CTR5(KTR_NET, "%20s: node [%x] (%p) requeued item %p as WRITER",
          __func__, ngq->q_node->nd_ID, ngq->q_node, item );

      /* Reverse what we did above. That downgrades us back to reader */
      atomic_add_long(&ngq->q_flags, READER_INCREMENT - WRITER_ACTIVE);
      if (NEXT_QUEUED_ITEM_CAN_PROCEED(ngq))
            ng_setisr(ngq->q_node);
      mtx_unlock_spin(&(ngq->q_mtx));

      return;
}

#endif

static __inline void
ng_leave_read(struct ng_queue *ngq)
{
      atomic_subtract_long(&ngq->q_flags, READER_INCREMENT);
}

static __inline void
ng_leave_write(struct ng_queue *ngq)
{
      atomic_subtract_long(&ngq->q_flags, WRITER_ACTIVE);
}

static void
ng_flush_input_queue(struct ng_queue * ngq)
{
      item_p item;

      NG_QUEUE_LOCK(ngq);
      while (ngq->queue) {
            item = ngq->queue;
            ngq->queue = item->el_next;
            if (ngq->last == &(item->el_next)) {
                  ngq->last = &(ngq->queue);
                  atomic_add_long(&ngq->q_flags, -OP_PENDING);
            }
            NG_QUEUE_UNLOCK(ngq);

            /* If the item is supplying a callback, call it with an error */
            if (item->apply != NULL &&
                refcount_release(&item->apply->refs)) {
                  (*item->apply->apply)(item->apply->context, ENOENT);
            }
            NG_FREE_ITEM(item);
            NG_QUEUE_LOCK(ngq);
      }
      /*
       * Take us off the work queue if we are there.
       * We definately have no work to be done.
       */
      ng_worklist_remove(ngq->q_node);
      NG_QUEUE_UNLOCK(ngq);
}

/***********************************************************************
* 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 queue, rw;
      struct ng_queue *ngq;
      int error = 0;

      if (item == NULL) {
            TRAP_ERROR();
            return (EINVAL);  /* failed to get queue element */
      }

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

      if (item->apply)
            refcount_acquire(&item->apply->refs);

      hook = NGI_HOOK(item);
      node = NGI_NODE(item);
      ngq = &node->nd_input_queue;
      if (node == NULL) {
            TRAP_ERROR();
            ERROUT(EINVAL);   /* No address */
      }

      queue = (flags & NG_QUEUE) ? 1 : 0;

      switch(item->el_flags & NGQF_TYPE) {
      case NGQF_DATA:
            /*
             * DATA MESSAGE
             * Delivered to a node via a non-optional hook.
             * Both should be present in the item even though
             * the node is derivable from the hook.
             * References are held on both by the item.
             */

            /* Protect nodes from sending NULL pointers
             * to each other
             */
            if (NGI_M(item) == NULL)
                  ERROUT(EINVAL);

            CHECK_DATA_MBUF(NGI_M(item));
            if (hook == NULL) {
                  TRAP_ERROR();
                  ERROUT(EINVAL);
            }
            if ((NG_HOOK_NOT_VALID(hook))
            || (NG_NODE_NOT_VALID(NG_HOOK_NODE(hook)))) {
                  ERROUT(ENOTCONN);
            }
            if ((hook->hk_flags & HK_QUEUE)) {
                  queue = 1;
            }
            break;
      case NGQF_MESG:
            /*
             * CONTROL MESSAGE
             * Delivered to a node.
             * Hook is optional.
             * References are held by the item on the node and
             * the hook if it is present.
             */
            if (hook && (hook->hk_flags & HK_QUEUE)) {
                  queue = 1;
            }
            break;
      case NGQF_FN:
      case NGQF_FN2:
            break;
      default:
            TRAP_ERROR();
            ERROUT(EINVAL);
      }
      switch(item->el_flags & NGQF_RW) {
      case NGQF_READER:
            rw = NGQRW_R;
            break;
      case NGQF_WRITER:
            rw = NGQRW_W;
            break;
      default:
            panic("%s: invalid item flags %lx", __func__, item->el_flags);
      }

      /*
       * If the node specifies single threading, force writer semantics.
       * Similarly, the node may say one hook always produces writers.
       * These are overrides.
       */
      if ((node->nd_flags & NGF_FORCE_WRITER)
          || (hook && (hook->hk_flags & HK_FORCE_WRITER)))
                  rw = NGQRW_W;

      if (queue) {
            /* Put it on the queue for that node*/
#ifdef      NETGRAPH_DEBUG
            _ngi_check(item, __FILE__, __LINE__);
#endif
            NG_QUEUE_LOCK(ngq);
            ng_queue_rw(ngq, item, rw);
            NG_QUEUE_UNLOCK(ngq);

            if (flags & NG_PROGRESS)
                  return (EINPROGRESS);
            else
                  return (0);
      }

      /*
       * We already decided how we will be queueud or treated.
       * Try get the appropriate operating permission.
       */
      if (rw == NGQRW_R)
            item = ng_acquire_read(ngq, item);
      else
            item = ng_acquire_write(ngq, item);


      if (item == NULL) {
            if (flags & NG_PROGRESS)
                  return (EINPROGRESS);
            else
                  return (0);
      }

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

      NGI_GET_NODE(item, node); /* zaps stored node */

      error = ng_apply_item(node, item, rw); /* drops r/w lock when done */

      /*
       * If the node goes away when we remove the reference,
       * whatever we just did caused it.. whatever we do, DO NOT
       * access the node again!
       */
      if (NG_NODE_UNREF(node) == 0) {
            return (error);
      }

      NG_QUEUE_LOCK(ngq);
      if (NEXT_QUEUED_ITEM_CAN_PROCEED(ngq))
            ng_setisr(ngq->q_node);
      NG_QUEUE_UNLOCK(ngq);

      return (error);

done:
      /* Apply callback. */
      if (item->apply != NULL &&
          refcount_release(&item->apply->refs)) {
            (*item->apply->apply)(item->apply->context, error);
      }
      NG_FREE_ITEM(item);
      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(node_p node, item_p item, int rw)
{
      hook_p  hook;
      int   error = 0;
      ng_rcvdata_t *rcvdata;
      ng_rcvmsg_t *rcvmsg;
      struct ng_apply_info *apply;

      NGI_GET_HOOK(item, hook); /* clears stored hook */
#ifdef      NETGRAPH_DEBUG
      _ngi_check(item, __FILE__, __LINE__);
#endif

      apply = item->apply;

      switch (item->el_flags & NGQF_TYPE) {
      case NGQF_DATA:
            /*
             * Check things are still ok as when we were queued.
             */
            if ((hook == NULL)
            || 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) {
                  if (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);
            } else {
                  /*
                   * 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..
                   */

                  struct ng_mesg *msg = NGI_MSG(item);

                  /*
                   * check if the generic handler owns it.
                   */
                  if ((msg->header.typecookie == NGM_GENERIC_COOKIE)
                  && ((msg->header.flags & NGF_RESP) == 0)) {
                        error = ng_generic_msg(node, item, hook);
                        break;
                  }
                  /*
                   * Now see if there is a handler (hook or node specific)
                   * in the target node. If none, silently discard.
                   */
                  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);
      }

      if (rw == NGQRW_R) {
            ng_leave_read(&node->nd_input_queue);
      } else {
            ng_leave_write(&node->nd_input_queue);
      }

      /* Apply callback. */
      if (apply != NULL &&
          refcount_release(&apply->refs)) {
            (*apply->apply)(apply->context, error);
      }

      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_NOWAIT);
            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_NOWAIT);
            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_LISTNAMES:
      case NGM_LISTNODES:
          {
            const int unnamed = (msg->header.cmd == NGM_LISTNODES);
            struct namelist *nl;
            node_p node;
            int num = 0;

            mtx_lock(&ng_nodelist_mtx);
            /* Count number of nodes */
            LIST_FOREACH(node, &ng_nodelist, nd_nodes) {
                  if (NG_NODE_IS_VALID(node)
                  && (unnamed || NG_NODE_HAS_NAME(node))) {
                        num++;
                  }
            }
            mtx_unlock(&ng_nodelist_mtx);

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

            /* Cycle through the linked list of nodes */
            nl->numnames = 0;
            mtx_lock(&ng_nodelist_mtx);
            LIST_FOREACH(node, &ng_nodelist, nd_nodes) {
                  struct nodeinfo *const np = &nl->nodeinfo[nl->numnames];

                  if (NG_NODE_NOT_VALID(node))
                        continue;
                  if (!unnamed && (! NG_NODE_HAS_NAME(node)))
                        continue;
                  if (nl->numnames >= num) {
                        log(LOG_ERR, "%s: number of %s changed\n",
                            __func__, "nodes");
                        break;
                  }
                  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;
                  nl->numnames++;
            }
            mtx_unlock(&ng_nodelist_mtx);
            break;
          }

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

            mtx_lock(&ng_typelist_mtx);
            /* Count number of types */
            LIST_FOREACH(type, &ng_typelist, types) {
                  num++;
            }
            mtx_unlock(&ng_typelist_mtx);

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

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

                  if (tl->numtypes >= num) {
                        log(LOG_ERR, "%s: number of %s changed\n",
                            __func__, "types");
                        break;
                  }
                  strcpy(tp->type_name, type->name);
                  tp->numnodes = type->refs - 1; /* don't count list */
                  tl->numtypes++;
            }
            mtx_unlock(&ng_typelist_mtx);
            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_NOWAIT);
            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 */
            snprintf(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_NOWAIT);
            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
************************************************************************/

uma_zone_t              ng_qzone;
static int              maxalloc = 512;   /* limit the damage of a leak */

TUNABLE_INT("net.graph.maxalloc", &maxalloc);
SYSCTL_INT(_net_graph, OID_AUTO, maxalloc, CTLFLAG_RDTUN, &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_getqblk(int flags)
{
      item_p item = NULL;
      int wait;

      wait = (flags & NG_WAITOK) ? M_WAITOK : M_NOWAIT;

      item = uma_zalloc(ng_qzone, wait | M_ZERO);

#ifdef      NETGRAPH_DEBUG
      if (item) {
                  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)
{
      /*
       * 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
      uma_zfree(ng_qzone, item);
}

/************************************************************************
                  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 s, error = 0;

      switch (event) {
      case MOD_LOAD:

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

            /* Call type specific code */
            if (type->mod_event != NULL)
                  if ((error = (*type->mod_event)(mod, event, data))) {
                        mtx_lock(&ng_typelist_mtx);
                        type->refs--;     /* undo it */
                        LIST_REMOVE(type, types);
                        mtx_unlock(&ng_typelist_mtx);
                  }
            splx(s);
            break;

      case MOD_UNLOAD:
            s = splnet();
            if (type->refs > 1) {         /* make sure no nodes exist! */
                  error = EBUSY;
            } else {
                  if (type->refs == 0) {
                        /* failed load, nothing to undo */
                        splx(s);
                        break;
                  }
                  if (type->mod_event != NULL) {      /* check with type */
                        error = (*type->mod_event)(mod, event, data);
                        if (error != 0) { /* type refuses.. */
                              splx(s);
                              break;
                        }
                  }
                  mtx_lock(&ng_typelist_mtx);
                  LIST_REMOVE(type, types);
                  mtx_unlock(&ng_typelist_mtx);
            }
            splx(s);
            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.
 * The only thing we need to link into is the NETISR strucure.
 */
static int
ngb_mod_event(module_t mod, int event, void *data)
{
      int error = 0;

      switch (event) {
      case MOD_LOAD:
            /* Initialize everything. */
            NG_WORKLIST_LOCK_INIT();
            mtx_init(&ng_typelist_mtx, "netgraph types mutex", NULL,
                MTX_DEF);
            mtx_init(&ng_nodelist_mtx, "netgraph nodelist mutex", NULL,
                MTX_DEF);
            mtx_init(&ng_idhash_mtx, "netgraph idhash mutex", NULL,
                MTX_DEF);
            mtx_init(&ng_topo_mtx, "netgraph topology mutex", NULL,
                MTX_DEF);
#ifdef      NETGRAPH_DEBUG
            mtx_init(&ngq_mtx, "netgraph item list mutex", NULL,
                MTX_DEF);
#endif
            ng_qzone = uma_zcreate("NetGraph items", sizeof(struct ng_item),
                NULL, NULL, NULL, NULL, UMA_ALIGN_CACHE, 0);
            uma_zone_set_max(ng_qzone, maxalloc);
            netisr_register(NETISR_NETGRAPH, (netisr_t *)ngintr, NULL,
                NETISR_MPSAFE);
            break;
      case MOD_UNLOAD:
            /* 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)
{
      printf("hook: name %s, %d refs, Last touched:\n",
            _NG_HOOK_NAME(hook), hook->hk_refs);
      printf("    Last active @ %s, line %d\n",
            hook->lastfile, hook->lastline);
      if (line) {
            printf(" problem discovered at file %s, line %d\n", file, line);
      }
}

void
dumpnode(node_p node, char *file, int line)
{
      printf("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);
      printf("    Last active @ %s, line %d\n",
            node->lastfile, node->lastline);
      if (line) {
            printf(" problem discovered at file %s, line %d\n", file, line);
      }
}

void
dumpitem(item_p item, char *file, int line)
{
      printf(" ACTIVE item, last used at %s, line %d",
            item->lastfile, item->lastline);
      switch(item->el_flags & NGQF_TYPE) {
      case NGQF_DATA:
            printf(" - [data]\n");
            break;
      case NGQF_MESG:
            printf(" - retaddr[%d]:\n", _NGI_RETADDR(item));
            break;
      case NGQF_FN:
            printf(" - 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:
            printf(" - 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) {
            printf(" problem discovered at file %s, line %d\n", file, line);
            if (_NGI_NODE(item)) {
                  printf("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) {
            printf("[%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) {
            printf("[%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) {
            printf("[%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;
      int i;

      val = allocated;
      i = 1;
      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 */


/***********************************************************************
* Worklist routines
**********************************************************************/
/* NETISR thread enters here */
/*
 * Pick a node off the list of nodes with work,
 * try get an item to process off it.
 * If there are no more, remove the node from the list.
 */
static void
ngintr(void)
{
      item_p item;
      node_p  node = NULL;

      for (;;) {
            NG_WORKLIST_LOCK();
            node = TAILQ_FIRST(&ng_worklist);
            if (!node) {
                  NG_WORKLIST_UNLOCK();
                  break;
            }
            node->nd_flags &= ~NGF_WORKQ; 
            TAILQ_REMOVE(&ng_worklist, node, nd_work);
            NG_WORKLIST_UNLOCK();
            CTR3(KTR_NET, "%20s: node [%x] (%p) taken off worklist",
                __func__, node->nd_ID, node);
            /*
             * We have the node. We also take over the reference
             * that the list had on it.
             * Now process as much as you can, until it won't
             * let you have another item off the queue.
             * All this time, keep the reference
             * that lets us be sure that the node still exists.
             * Let the reference go at the last minute.
             * ng_dequeue will put us back on the worklist
             * if there is more too do. This may be of use if there
             * are Multiple Processors and multiple Net threads in the
             * future.
             */
            for (;;) {
                  int rw;

                  NG_QUEUE_LOCK(&node->nd_input_queue);
                  item = ng_dequeue(&node->nd_input_queue, &rw);
                  if (item == NULL) {
                        NG_QUEUE_UNLOCK(&node->nd_input_queue);
                        break; /* go look for another node */
                  } else {
                        NG_QUEUE_UNLOCK(&node->nd_input_queue);
                        NGI_GET_NODE(item, node); /* zaps stored node */
                        ng_apply_item(node, item, rw);
                        NG_NODE_UNREF(node);
                  }
            }
            NG_NODE_UNREF(node);
      }
}

static void
ng_worklist_remove(node_p node)
{
      mtx_assert(&node->nd_input_queue.q_mtx, MA_OWNED);

      NG_WORKLIST_LOCK();
      if (node->nd_flags & NGF_WORKQ) {
            node->nd_flags &= ~NGF_WORKQ;
            TAILQ_REMOVE(&ng_worklist, node, nd_work);
            NG_WORKLIST_UNLOCK();
            NG_NODE_UNREF(node);
            CTR3(KTR_NET, "%20s: node [%x] (%p) removed from worklist",
                __func__, node->nd_ID, node);
      } else {
            NG_WORKLIST_UNLOCK();
      }
}

/*
 * XXX
 * It's posible that a debugging NG_NODE_REF may need
 * to be outside the mutex zone
 */
static void
ng_setisr(node_p node)
{

      mtx_assert(&node->nd_input_queue.q_mtx, MA_OWNED);

      if ((node->nd_flags & NGF_WORKQ) == 0) {
            /*
             * If we are not already on the work queue,
             * then put us on.
             */
            node->nd_flags |= NGF_WORKQ;
            NG_WORKLIST_LOCK();
            TAILQ_INSERT_TAIL(&ng_worklist, node, nd_work);
            NG_WORKLIST_UNLOCK();
            NG_NODE_REF(node); /* XXX fafe in mutex? */
            CTR3(KTR_NET, "%20s: node [%x] (%p) put on worklist", __func__,
                node->nd_ID, node);
      } else
            CTR3(KTR_NET, "%20s: node [%x] (%p) already on worklist",
                __func__, node->nd_ID, node);
      schednetisr(NETISR_NETGRAPH);
}


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

#ifdef      NETGRAPH_DEBUG
#define     ITEM_DEBUG_CHECKS                               \
      do {                                            \
            if (NGI_NODE(item) ) {                          \
                  printf("item already has node");          \
                  kdb_enter("has node");                    \
                  NGI_CLR_NODE(item);                       \
            }                                         \
            if (NGI_HOOK(item) ) {                          \
                  printf("item already has hook");          \
                  kdb_enter("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_getqblk(flags)) == NULL) {
            NG_FREE_M(m);
            return (NULL);
      }
      ITEM_DEBUG_CHECKS;
      item->el_flags = NGQF_DATA | NGQF_READER;
      item->el_next = NULL;
      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_getqblk(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_MESG | NGQF_READER;
      else
            item->el_flags = NGQF_MESG | NGQF_WRITER;
      item->el_next = NULL;
      /*
       * 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_PEER(hook) == NULL)
      || NG_HOOK_NOT_VALID(NG_HOOK_PEER(hook))
      || NG_NODE_NOT_VALID(NG_PEER_NODE(hook))) {
            NG_FREE_ITEM(item);
            TRAP_ERROR();
            return (ENETDOWN);
      }

      /*
       * Transfer our interest to the other (peer) end.
       */
      peer = NG_HOOK_PEER(hook);
      NG_HOOK_REF(peer);
      NGI_SET_HOOK(item, peer);
      peernode = NG_PEER_NODE(hook);
      NG_NODE_REF(peernode);
      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_getqblk(NG_NOFLAGS)) == NULL) {
            NG_FREE_MSG(msg);
            return (NULL);
      }

      /* Fill out the contents */
      item->el_flags = NGQF_MESG | NGQF_WRITER;
      item->el_next = NULL;
      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_getqblk(flags)) == NULL) {
            return (ENOMEM);
      }
      item->el_flags = NGQF_FN | 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 an optional pitem parameter is supplied, its apply
 * callback will be copied to the new item. If also NG_REUSE_ITEM
 * flag is set, no new item will be allocated, but pitem will
 * be used.
 */
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_getqblk(flags)) == NULL)
                  return (ENOMEM);
      } else
            item = pitem;

      item->el_flags = NGQF_FN2 | 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;
      if (pitem != NULL && (flags & NG_REUSE_ITEM) == 0)
            item->apply = pitem->apply;
      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_getqblk(NG_NOFLAGS)) == NULL)
            return (ENOMEM);

      item->el_flags = NGQF_FN | 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 = c->c_arg;
      if (callout_reset(c, ticks, &ng_callout_trampoline, item) == 1 &&
          oitem != NULL)
            NG_FREE_ITEM(oitem);
      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 = c->c_arg;
      /* Do an extra check */
      if ((rval > 0) && (c->c_func == &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);
      }
      c->c_arg = 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);
      }
}

#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 */


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