text: /*
   * ng_socket.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.
   *
   * Author: Julian Elischer <julian@freebsd.org>
   *
   * $FreeBSD: src/sys/netgraph/ng_socket.c,v 1.85 2008/03/11 21:58:48 mav Exp $
   * $Whistle: ng_socket.c,v 1.28 1999/11/01 09:24:52 julian Exp $
   */
  
  /*
   * Netgraph socket nodes
   *
   * There are two types of netgraph sockets, control and data.
   * Control sockets have a netgraph node, but data sockets are
   * parasitic on control sockets, and have no node of their own.
   */
  
  #include <sys/domain.h>
  #include <sys/kernel.h>
  #include <sys/linker.h>
  #include <sys/lock.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <sys/msgport2.h>
  /*
  #include <sys/mutex.h>
  */
  #include <sys/param.h>
  #include <sys/priv.h>
  #include <sys/proc.h>
  #include <sys/protosw.h>
  #include <sys/queue.h>
  #include <sys/socket.h>
  #include <sys/socketvar.h>
  #include <sys/socketvar2.h>
  /*
  #include <sys/syscallsubr.h>
  */
  #include <sys/sysctl.h>
  #include <sys/vnode.h>
  
  #include <netgraph7/ng_message.h>
  #include <netgraph7/netgraph.h>
  #include "ng_socketvar.h"
  #include "ng_socket.h"
  
  #ifdef NG_SEPARATE_MALLOC
  MALLOC_DEFINE(M_NETGRAPH_PATH, "netgraph_path", "netgraph path info ");
  MALLOC_DEFINE(M_NETGRAPH_SOCK, "netgraph_sock", "netgraph socket info ");
  #else
  #define M_NETGRAPH_PATH M_NETGRAPH
  #define M_NETGRAPH_SOCK M_NETGRAPH
  #endif
  
  /*
   * It's Ascii-art time!
   *   +-------------+   +-------------+
   *   |socket  (ctl)|   |socket (data)|
   *   +-------------+   +-------------+
   *          ^                 ^
   *          |                 |
   *          v                 v
   *    +-----------+     +-----------+
   *    |pcb   (ctl)|     |pcb  (data)|
   *    +-----------+     +-----------+
   *          ^                 ^
   *          |                 |
   *          v                 v
   *      +--------------------------+
   *      |   Socket type private    |
   *      |       data               |
   *      +--------------------------+
   *                   ^
   *                   |
   *                   v
   *           +----------------+
   *           | struct ng_node |
   *           +----------------+
   */
  
  /* Netgraph node methods */
  static ng_constructor_t	ngs_constructor;
  static ng_rcvmsg_t	ngs_rcvmsg;
  static ng_shutdown_t	ngs_shutdown;
  static ng_newhook_t	ngs_newhook;
  static ng_connect_t	ngs_connect;
  static ng_rcvdata_t	ngs_rcvdata;
  static ng_disconnect_t	ngs_disconnect;
  
  /* Internal methods */
  static int	ng_attach_data(struct socket *so);
  static int	ng_attach_cntl(struct socket *so);
  static int	ng_attach_common(struct socket *so, int type);
  static void	ng_detach_common(struct ngpcb *pcbp, int type);
  static void	ng_socket_free_priv(struct ngsock *priv);
  #ifdef NOTYET
  static int	ng_internalize(struct mbuf *m, struct thread *p);
  #endif
  static int	ng_connect_data(struct sockaddr *nam, struct ngpcb *pcbp);
  static int	ng_bind(struct sockaddr *nam, struct ngpcb *pcbp);
  
  static int	ngs_mod_event(module_t mod, int event, void *data);
  static void	ng_socket_item_applied(void *context, int error);
  static int	linker_api_available(void);
  
  /* Netgraph type descriptor */
  static struct ng_type typestruct = {
  	.version =	NG_ABI_VERSION,
  	.name =		NG_SOCKET_NODE_TYPE,
  	.mod_event =	ngs_mod_event,
  	.constructor =	ngs_constructor,
  	.rcvmsg =	ngs_rcvmsg,
  	.shutdown =	ngs_shutdown,
  	.newhook =	ngs_newhook,
  	.connect =	ngs_connect,
  	.rcvdata =	ngs_rcvdata,
  	.disconnect =	ngs_disconnect,
  };
  NETGRAPH_INIT_ORDERED(socket, &typestruct, SI_SUB_PROTO_DOMAIN, SI_ORDER_ANY);
  
  /* Buffer space */
  static u_long ngpdg_sendspace = 20 * 1024;	/* really max datagram size */
  SYSCTL_INT(_net_graph, OID_AUTO, maxdgram, CTLFLAG_RW,
      &ngpdg_sendspace , 0, "Maximum outgoing Netgraph datagram size");
  static u_long ngpdg_recvspace = 20 * 1024;
  SYSCTL_INT(_net_graph, OID_AUTO, recvspace, CTLFLAG_RW,
      &ngpdg_recvspace , 0, "Maximum space for incoming Netgraph datagrams");
  
  #define sotongpcb(so) ((struct ngpcb *)(so)->so_pcb)
  
  /* If getting unexplained errors returned, set this to "kdb_enter("X"); */
  #ifndef TRAP_ERROR
  #define TRAP_ERROR
  #endif
  
  /***************************************************************
  	Control sockets
  ***************************************************************/
  
  static void
  ngc_attach(netmsg_t msg)
  {
  	struct socket *so = msg->attach.base.nm_so;
  	struct pru_attach_info *ai = msg->attach.nm_ai;
  	struct ngpcb *const pcbp = sotongpcb(so);
  	int error;
  
  	if (priv_check_cred(ai->p_ucred, PRIV_ROOT, NULL_CRED_OKAY) != 0)
  		error = EPERM;
  	else if (pcbp != NULL)
  		error = EISCONN;
  	else
  		error = ng_attach_cntl(so);
  	lwkt_replymsg(&msg->attach.base.lmsg, error);
  }
  
  static void
  ngc_detach(netmsg_t msg)
  {
  	struct socket *so = msg->detach.base.nm_so;
  	struct ngpcb *const pcbp = sotongpcb(so);
  
  	KASSERT(pcbp != NULL, ("ngc_detach: pcbp == NULL"));
  	ng_detach_common(pcbp, NG_CONTROL);
  	lwkt_replymsg(&msg->detach.base.lmsg, 0);
  }
  
  static void
  ngc_send(netmsg_t netmsg)
  {
  	struct socket *so = netmsg->send.base.nm_so;
  	struct mbuf *m = netmsg->send.nm_m;
  	struct sockaddr *addr = netmsg->send.nm_addr;
  	struct mbuf *control = netmsg->send.nm_control;
  	struct ngpcb *const pcbp = sotongpcb(so);
  	struct sockaddr_ng *const sap = (struct sockaddr_ng *) addr;
  	struct ng_mesg *msg;
  	struct mbuf *m0;
  	item_p item;
  	char *path = NULL;
  	int len, error = 0;
  	struct ng_apply_info *apply;
  
  #ifdef	NOTYET
  	if (control && (error = ng_internalize(control, td))) {
  		if (pcbp->sockdata == NULL) {
  			error = ENOTCONN;
  			goto release;
  		}
  	}
  #else	/* NOTYET */
  	if (control) {
  		error = EINVAL;
  		goto release;
  	}
  #endif	/* NOTYET */
  
  	/* Require destination as there may be >= 1 hooks on this node. */
  	if (addr == NULL) {
  		error = EDESTADDRREQ;
  		goto release;
  	}
  
  	/*
  	 * Allocate an expendable buffer for the path, chop off
  	 * the sockaddr header, and make sure it's NUL terminated.
  	 */
  	len = sap->sg_len - 2;
  	path = kmalloc(len + 1, M_NETGRAPH_PATH, M_WAITOK);
  	bcopy(sap->sg_data, path, len);
  	path[len] = '\0';
  
  	/*
  	 * Move the actual message out of mbufs into a linear buffer.
  	 * Start by adding up the size of the data. (could use mh_len?)
  	 */
  	for (len = 0, m0 = m; m0 != NULL; m0 = m0->m_next)
  		len += m0->m_len;
  
  	/*
  	 * Move the data into a linear buffer as well.
  	 * Messages are not delivered in mbufs.
  	 */
  	msg = kmalloc(len + 1, M_NETGRAPH_MSG, M_WAITOK);
  	m_copydata(m, 0, len, (char *)msg);
  
  	if (msg->header.version != NG_VERSION) {
  		kfree(msg, M_NETGRAPH_MSG);
  		error = EINVAL;
  		goto release;
  	}
  
  	/*
  	 * Hack alert!
  	 * We look into the message and if it mkpeers a node of unknown type, we
  	 * try to load it. We need to do this now, in syscall thread, because if
  	 * message gets queued and applied later we will get panic.
  	 */
  	if (msg->header.typecookie == NGM_GENERIC_COOKIE &&
  	    msg->header.cmd == NGM_MKPEER) {
  		struct ngm_mkpeer *const mkp = (struct ngm_mkpeer *) msg->data;
  		struct ng_type *type;
  
  		if ((type = ng_findtype(mkp->type)) == NULL) {
  			char filename[NG_TYPESIZ + 3];
  			linker_file_t fileid;
  
  			if (!linker_api_available()) {
  				error = ENXIO;
  				goto done;
  			}
  
  			/* Not found, try to load it as a loadable module. */
  			ksnprintf(filename, sizeof(filename), "ng_%s.ko",
  			    mkp->type);
  			error = linker_load_file(filename, &fileid);
  			if (error != 0) {
  				kfree(msg, M_NETGRAPH_MSG);
  				goto release;
  			}
  
  			/* See if type has been loaded successfully. */
  			if ((type = ng_findtype(mkp->type)) == NULL) {
  				kfree(msg, M_NETGRAPH_MSG);
  				(void)linker_file_unload(fileid);
  				error =  ENXIO;
  				goto release;
  			}
  		}
  	}
  
  	item = ng_package_msg(msg, NG_WAITOK);
  	if ((error = ng_address_path((pcbp->sockdata->node), item, path, 0))
  	    != 0) {
  #ifdef TRACE_MESSAGES
  		kprintf("ng_address_path: errx=%d\n", error);
  #endif
  		goto release;
  	}
  
  #ifdef TRACE_MESSAGES
  	kprintf("[%x]:<---------[socket]: c=<%d>cmd=%x(%s) f=%x #%d (%s)\n",
  		item->el_dest->nd_ID,
  		msg->header.typecookie,
  		msg->header.cmd,
  		msg->header.cmdstr,
  		msg->header.flags,
  		msg->header.token,
  		item->el_dest->nd_type->name);
  #endif
  	SAVE_LINE(item);
  
  	/*
  	 * We do not want the user thread to return from syscall until the
  	 * item is processed by destination node.  We register callback
  	 * on the item, which will reply to the user thread when item
  	 * was applied.
  	 */
  	apply = ng_alloc_apply();
  	bzero(apply, sizeof(*apply));
  	apply->apply = ng_socket_item_applied;
  	apply->context = &netmsg->send.base.lmsg;
  	item->apply = apply;
  
  	error = ng_snd_item(item, NG_PROGRESS);
  
  release:
  	if (path != NULL)
  		kfree(path, M_NETGRAPH_PATH);
  	if (control != NULL)
  		m_freem(control);
  	if (m != NULL)
  		m_freem(m);
  done:
  	if (error != EINPROGRESS)
  		lwkt_replymsg(&netmsg->send.base.lmsg, error);
  }
  
  static void
  ngc_bind(netmsg_t msg)
  {
  	struct socket *so = msg->connect.base.nm_so;
  	struct sockaddr *nam = msg->connect.nm_nam;
  	struct ngpcb *const pcbp = sotongpcb(so);
  	int error;
  
  	if (pcbp == NULL)
  		error = EINVAL;
  	else
  		error = ng_bind(nam, pcbp);
  	lwkt_replymsg(&msg->connect.base.lmsg, error);
  }
  
  static void
  ngc_connect(netmsg_t msg)
  {
  	/*
  	 * At this time refuse to do this.. it used to
  	 * do something but it was undocumented and not used.
  	 */
  	kprintf("program tried to connect control socket to remote node\n");
  	lwkt_replymsg(&msg->connect.base.lmsg, EINVAL);
  }
  
  /***************************************************************
  	Data sockets
  ***************************************************************/
  
  static void
  ngd_attach(netmsg_t msg)
  {
  	struct socket *so = msg->attach.base.nm_so;
  	struct ngpcb *const pcbp = sotongpcb(so);
  	int error;
  
  	if (pcbp != NULL)
  		error =  EISCONN;
  	else
  		error = ng_attach_data(so);
  	lwkt_replymsg(&msg->connect.base.lmsg, error);
  }
  
  static void
  ngd_detach(netmsg_t msg)
  {
  	struct socket *so = msg->detach.base.nm_so;
  	struct ngpcb *const pcbp = sotongpcb(so);
  
  	KASSERT(pcbp != NULL, ("ngd_detach: pcbp == NULL"));
  	ng_detach_common(pcbp, NG_DATA);
  	lwkt_replymsg(&msg->detach.base.lmsg, 0);
  }
  
  static void
  ngd_send(netmsg_t msg)
  {
  	struct socket *so = msg->send.base.nm_so;
  	struct mbuf *m = msg->send.nm_m;
  	struct sockaddr *addr = msg->send.nm_addr;
  	struct mbuf *control = msg->send.nm_control;
  	struct ngpcb *const pcbp = sotongpcb(so);
  	struct sockaddr_ng *const sap = (struct sockaddr_ng *) addr;
  	int	len, error;
  	hook_p  hook = NULL;
  	char	hookname[NG_HOOKSIZ];
  
  	if ((pcbp == NULL) || (control != NULL)) {
  		error = EINVAL;
  		goto release;
  	}
  	if (pcbp->sockdata == NULL) {
  		error = ENOTCONN;
  		goto release;
  	}
  
  	if (sap == NULL)
  		len = 0;		/* Make compiler happy. */
  	else
  		len = sap->sg_len - 2;
  
  	/*
  	 * If the user used any of these ways to not specify an address
  	 * then handle specially.
  	 */
  	if ((sap == NULL) || (len <= 0) || (*sap->sg_data == '\0')) {
  		if (NG_NODE_NUMHOOKS(pcbp->sockdata->node) != 1) {
  			error = EDESTADDRREQ;
  			goto release;
  		}
  		/*
  		 * If exactly one hook exists, just use it.
  		 * Special case to allow write(2) to work on an ng_socket.
  		 */
  		hook = LIST_FIRST(&pcbp->sockdata->node->nd_hooks);
  	} else {
  		if (len >= NG_HOOKSIZ) {
  			error = EINVAL;
  			goto release;
  		}
  
  		/*
  		 * chop off the sockaddr header, and make sure it's NUL
  		 * terminated
  		 */
  		bcopy(sap->sg_data, hookname, len);
  		hookname[len] = '\0';
  
  		/* Find the correct hook from 'hookname' */
  		hook = ng_findhook(pcbp->sockdata->node, hookname);
  		if (hook == NULL) {
  			error = EHOSTUNREACH;
  			goto release;
  		}
  	}
  
  	/* Send data. */
  	NG_SEND_DATA_FLAGS(error, hook, m, NG_WAITOK);
  
  release:
  	if (control != NULL)
  		m_freem(control);
  	if (m != NULL)
  		m_freem(m);
  	lwkt_replymsg(&msg->send.base.lmsg, error);
  }
  
  static void
  ngd_connect(netmsg_t msg)
  {
  	struct socket *so = msg->connect.base.nm_so;
  	struct sockaddr *nam = msg->connect.nm_nam;
  	struct ngpcb *const pcbp = sotongpcb(so);
  	int error;
  
  	if (pcbp == NULL)
  		error = EINVAL;
  	else
  		error = ng_connect_data(nam, pcbp);
  	lwkt_replymsg(&msg->connect.base.lmsg, error);
  }
  
  /*
   * Used for both data and control sockets
   */
  static void
  ng_getsockaddr(netmsg_t msg)
  {
  	struct socket *so = msg->sockaddr.base.nm_so;
  	struct sockaddr **addr = msg->sockaddr.nm_nam;
  	struct ngpcb *pcbp;
  	struct sockaddr_ng *sg;
  	int sg_len;
  	int error = 0;
  
  	/* Why isn't sg_data a `char[1]' ? :-( */
  	sg_len = sizeof(struct sockaddr_ng) - sizeof(sg->sg_data) + 1;
  
  	pcbp = sotongpcb(so);
  	if ((pcbp == NULL) || (pcbp->sockdata == NULL)) {
  		/* XXXGL: can this still happen? */
  		error = EINVAL;
  		goto replymsg;
  	}
  
  	mtx_lock(&pcbp->sockdata->mtx);
  	if (pcbp->sockdata->node != NULL) {
  		node_p node = pcbp->sockdata->node;
  		int namelen = 0;	/* silence compiler! */
  
  		if (NG_NODE_HAS_NAME(node))
  			sg_len += namelen = strlen(NG_NODE_NAME(node));
  
  		sg = kmalloc(sg_len, M_SONAME, M_WAITOK | M_ZERO);
  
  		if (NG_NODE_HAS_NAME(node))
  			bcopy(NG_NODE_NAME(node), sg->sg_data, namelen);
  
  		sg->sg_len = sg_len;
  		sg->sg_family = AF_NETGRAPH;
  		*addr = (struct sockaddr *)sg;
  		mtx_unlock(&pcbp->sockdata->mtx);
  	} else {
  		mtx_unlock(&pcbp->sockdata->mtx);
  		error = EINVAL;
  	}
  
  replymsg:
  	lwkt_replymsg(&msg->sockaddr.base.lmsg, error);
  }
  
  /*
   * Attach a socket to it's protocol specific partner.
   * For a control socket, actually create a netgraph node and attach
   * to it as well.
   */
  
  static int
  ng_attach_cntl(struct socket *so)
  {
  	struct ngsock *priv;
  	struct ngpcb *pcbp;
  	int error;
  
  	/* Allocate node private info */
  	priv = kmalloc(sizeof(*priv), M_NETGRAPH_SOCK, M_WAITOK | M_ZERO);
  
  	/* Setup protocol control block */
  	if ((error = ng_attach_common(so, NG_CONTROL)) != 0) {
  		kfree(priv, M_NETGRAPH_SOCK);
  		return (error);
  	}
  	pcbp = sotongpcb(so);
  
  	/* Link the pcb the private data. */
  	priv->ctlsock = pcbp;
  	pcbp->sockdata = priv;
  	priv->refs++;
  
  	/* Initialize mutex. */
  	mtx_init(&priv->mtx, "ng_socket");
  
  	/* Make the generic node components */
  	if ((error = ng_make_node_common(&typestruct, &priv->node)) != 0) {
  		kfree(priv, M_NETGRAPH_SOCK);
  		ng_detach_common(pcbp, NG_CONTROL);
  		return (error);
  	}
  
  	/* Link the node and the private data. */
  	NG_NODE_SET_PRIVATE(priv->node, priv);
  	NG_NODE_REF(priv->node);
  	priv->refs++;
  
  	return (0);
  }
  
  static int
  ng_attach_data(struct socket *so)
  {
  	return (ng_attach_common(so, NG_DATA));
  }
  
  /*
   * Set up a socket protocol control block.
   * This code is shared between control and data sockets.
   */
  static int
  ng_attach_common(struct socket *so, int type)
  {
  	struct ngpcb *pcbp;
  	int error;
  
  	/* Standard socket setup stuff. */
  	error = soreserve(so, ngpdg_sendspace, ngpdg_recvspace, NULL);
  	if (error)
  		return (error);
  
  	/* Allocate the pcb. */
  	pcbp = kmalloc(sizeof(struct ngpcb), M_PCB, M_WAITOK | M_ZERO);
  	pcbp->type = type;
  
  	/* Link the pcb and the socket. */
  	so->so_pcb = (caddr_t)pcbp;
  	pcbp->ng_socket = so;
  
  	return (0);
  }
  
  /*
   * Disassociate the socket from it's protocol specific
   * partner. If it's attached to a node's private data structure,
   * then unlink from that too. If we were the last socket attached to it,
   * then shut down the entire node. Shared code for control and data sockets.
   */
  static void
  ng_detach_common(struct ngpcb *pcbp, int which)
  {
  	struct ngsock *priv = pcbp->sockdata;
  
  	if (priv != NULL) {
  		mtx_lock(&priv->mtx);
  
  		switch (which) {
  		case NG_CONTROL:
  			priv->ctlsock = NULL;
  			break;
  		case NG_DATA:
  			priv->datasock = NULL;
  			break;
  		default:
  			panic(__func__);
  		}
  		pcbp->sockdata = NULL;
  
  		ng_socket_free_priv(priv);
  	}
  
  	pcbp->ng_socket->so_pcb = NULL;
  	kfree(pcbp, M_PCB);
  }
  
  /*
   * Remove a reference from node private data.
   */
  static void
  ng_socket_free_priv(struct ngsock *priv)
  {
  	KKASSERT(mtx_owned(&priv->mtx));
  
  	priv->refs--;
  
  	if (priv->refs == 0) {
  		mtx_uninit(&priv->mtx);
  		kfree(priv, M_NETGRAPH_SOCK);
  		return;
  	}
  
  	if ((priv->refs == 1) && (priv->node != NULL)) {
  		node_p node = priv->node;
  
  		priv->node = NULL;
  		mtx_unlock(&priv->mtx);
  		NG_NODE_UNREF(node);
  		ng_rmnode_self(node);
  	} else
  		mtx_unlock(&priv->mtx);
  }
  
  #ifdef NOTYET
  /*
   * File descriptors can be passed into an AF_NETGRAPH socket.
   * Note, that file descriptors cannot be passed OUT.
   * Only character device descriptors are accepted.
   * Character devices are useful to connect a graph to a device,
   * which after all is the purpose of this whole system.
   */
  static int
  ng_internalize(struct mbuf *control, struct thread *td)
  {
  	const struct cmsghdr *cm = mtod(control, const struct cmsghdr *);
  	struct file *fp;
  	struct vnode *vn;
  	int oldfds;
  	int fd;
  
  	if (cm->cmsg_type != SCM_RIGHTS || cm->cmsg_level != SOL_SOCKET ||
  	    cm->cmsg_len != control->m_len) {
  		TRAP_ERROR;
  		return (EINVAL);
  	}
  
  	/* Check there is only one FD. XXX what would more than one signify? */
  	oldfds = ((caddr_t)cm + cm->cmsg_len - (caddr_t)data) / sizeof (int);
  	if (oldfds != 1) {
  		TRAP_ERROR;
  		return (EINVAL);
  	}
  
  	/* Check that the FD given is legit. and change it to a pointer to a
  	 * struct file. */
  	fd = CMSG_DATA(cm);
  	if ((error = fget(td, fd, &fp)) != 0)
  		return (error);
  
  	/* Depending on what kind of resource it is, act differently. For
  	 * devices, we treat it as a file. For an AF_NETGRAPH socket,
  	 * shortcut straight to the node. */
  	switch (fp->f_type) {
  	case DTYPE_VNODE:
  		vn = fp->f_data;
  		if (vn && (vn->v_type == VCHR)) {
  			/* for a VCHR, actually reference the FILE */
  			fhold(fp);
  			/* XXX then what :) */
  			/* how to pass on to other modules? */
  		} else {
  			fdrop(fp, td);
  			TRAP_ERROR;
  			return (EINVAL);
  		}
  		break;
  	default:
  		fdrop(fp, td);
  		TRAP_ERROR;
  		return (EINVAL);
  	}
  	fdrop(fp, td);
  	return (0);
  }
  #endif	/* NOTYET */
  
  /*
   * Connect the data socket to a named control socket node.
   */
  static int
  ng_connect_data(struct sockaddr *nam, struct ngpcb *pcbp)
  {
  	struct sockaddr_ng *sap;
  	node_p farnode;
  	struct ngsock *priv;
  	int error;
  	item_p item;
  
  	/* If we are already connected, don't do it again. */
  	if (pcbp->sockdata != NULL)
  		return (EISCONN);
  
  	/*
  	 * Find the target (victim) and check it doesn't already have
  	 * a data socket. Also check it is a 'socket' type node.
  	 * Use ng_package_data() and ng_address_path() to do this.
  	 */
  
  	sap = (struct sockaddr_ng *) nam;
  	/* The item will hold the node reference. */
  	item = ng_package_data(NULL, NG_WAITOK);
  
  	if ((error = ng_address_path(NULL, item,  sap->sg_data, 0))) {
  		ng_free_item(item);
  		return (error);
  	}
  
  	/*
  	 * Extract node from item and free item. Remember we now have
  	 * a reference on the node. The item holds it for us.
  	 * when we free the item we release the reference.
  	 */
  	farnode = item->el_dest; /* shortcut */
  	if (strcmp(farnode->nd_type->name, NG_SOCKET_NODE_TYPE) != 0) {
  		ng_free_item(item); /* drop the reference to the node */
  		return (EINVAL);
  	}
  	priv = NG_NODE_PRIVATE(farnode);
  	if (priv->datasock != NULL) {
  		ng_free_item(item);	/* drop the reference to the node */
  		return (EADDRINUSE);
  	}
  
  	/*
  	 * Link the PCB and the private data struct. and note the extra
  	 * reference. Drop the extra reference on the node.
  	 */
  	mtx_lock(&priv->mtx);
  	priv->datasock = pcbp;
  	pcbp->sockdata = priv;
  	priv->refs++;
  	mtx_unlock(&priv->mtx);
  	ng_free_item(item);	/* drop the reference to the node */
  	return (0);
  }
  
  /*
   * Binding a socket means giving the corresponding node a name
   */
  static int
  ng_bind(struct sockaddr *nam, struct ngpcb *pcbp)
  {
  	struct ngsock *const priv = pcbp->sockdata;
  	struct sockaddr_ng *const sap = (struct sockaddr_ng *) nam;
  
  	if (priv == NULL) {
  		TRAP_ERROR;
  		return (EINVAL);
  	}
  	if ((sap->sg_len < 4) || (sap->sg_len > (NG_NODESIZ + 2)) ||
  	    (sap->sg_data[0] == '\0') ||
  	    (sap->sg_data[sap->sg_len - 3] != '\0')) {
  		TRAP_ERROR;
  		return (EINVAL);
  	}
  	return (ng_name_node(priv->node, sap->sg_data));
  }
  
  /***************************************************************
  	Netgraph node
  ***************************************************************/
  
  /*
   * You can only create new nodes from the socket end of things.
   */
  static int
  ngs_constructor(node_p nodep)
  {
  	return (EINVAL);
  }
  
  /*
   * We allow any hook to be connected to the node.
   * There is no per-hook private information though.
   */
  static int
  ngs_newhook(node_p node, hook_p hook, const char *name)
  {
  	NG_HOOK_SET_PRIVATE(hook, NG_NODE_PRIVATE(node));
  	return (0);
  }
  
  /*
   * If only one hook, allow read(2) and write(2) to work.
   */
  static int
  ngs_connect(hook_p hook)
  {
  	node_p node = NG_HOOK_NODE(hook);
  	struct ngsock *priv = NG_NODE_PRIVATE(node);
  
  	if ((priv->datasock) && (priv->datasock->ng_socket)) {
  		if (NG_NODE_NUMHOOKS(node) == 1)
  			sosetstate(priv->datasock->ng_socket, SS_ISCONNECTED);
  		else
  			soclrstate(priv->datasock->ng_socket, SS_ISCONNECTED);
  	}
  	return (0);
  }
  
  /*
   * Incoming messages get passed up to the control socket.
   * Unless they are for us specifically (socket_type)
   */
  static int
  ngs_rcvmsg(node_p node, item_p item, hook_p lasthook)
  {
  	struct ngsock *const priv = NG_NODE_PRIVATE(node);
  	struct ngpcb *const pcbp = priv->ctlsock;
  	struct socket *so;
  	struct sockaddr_ng addr;
  	struct ng_mesg *msg;
  	struct mbuf *m;
  	ng_ID_t	retaddr = NGI_RETADDR(item);
  	int addrlen;
  	int error = 0;
  
  	NGI_GET_MSG(item, msg);
  	NG_FREE_ITEM(item);
  
  	/*
  	 * Only allow mesgs to be passed if we have the control socket.
  	 * Data sockets can only support the generic messages.
  	 */
  	if (pcbp == NULL) {
  		TRAP_ERROR;
  		NG_FREE_MSG(msg);
  		return (EINVAL);
  	}
  	so = pcbp->ng_socket;
  
  #ifdef TRACE_MESSAGES
  	kprintf("[%x]:---------->[socket]: c=<%d>cmd=%x(%s) f=%x #%d\n",
  		retaddr,
  		msg->header.typecookie,
  		msg->header.cmd,
  		msg->header.cmdstr,
  		msg->header.flags,
  		msg->header.token);
  #endif
  
  	if (msg->header.typecookie == NGM_SOCKET_COOKIE) {
  		switch (msg->header.cmd) {
  		case NGM_SOCK_CMD_NOLINGER:
  			priv->flags |= NGS_FLAG_NOLINGER;
  			break;
  		case NGM_SOCK_CMD_LINGER:
  			priv->flags &= ~NGS_FLAG_NOLINGER;
  			break;
  		default:
  			error = EINVAL;		/* unknown command */
  		}
  		/* Free the message and return. */
  		NG_FREE_MSG(msg);
  		return (error);
  	}
  
  	/* Get the return address into a sockaddr. */
  	bzero(&addr, sizeof(addr));
  	addr.sg_len = sizeof(addr);
  	addr.sg_family = AF_NETGRAPH;
  	addrlen = ksnprintf((char *)&addr.sg_data, sizeof(addr.sg_data),
  	    "[%x]:", retaddr);
  	if (addrlen < 0 || addrlen > sizeof(addr.sg_data)) {
  		kprintf("%s: ksnprintf([%x]) failed - %d\n", __func__, retaddr,
  		    addrlen);
  		NG_FREE_MSG(msg);
  		return (EINVAL);
  	}
  
  	/* Copy the message itself into an mbuf chain. */
  	m = m_devget((caddr_t)msg, sizeof(struct ng_mesg) + msg->header.arglen,
  		     0, NULL);
  
  	/*
  	 * Here we free the message. We need to do that
  	 * regardless of whether we got mbufs.
  	 */
  	NG_FREE_MSG(msg);
  
  	if (m == NULL) {
  		TRAP_ERROR;
  		return (ENOBUFS);
  	}
  
  	/* Send it up to the socket. */
  	lwkt_gettoken(&so->so_rcv.ssb_token);
  	if (sbappendaddr((struct sockbuf *)&so->so_rcv, (struct sockaddr *)&addr, m, NULL) == 0) {
  		lwkt_reltoken(&so->so_rcv.ssb_token);
  		TRAP_ERROR;
  		m_freem(m);
  		return (ENOBUFS);
  	}
  	lwkt_reltoken(&so->so_rcv.ssb_token);
  	sorwakeup(so);
  	
  	return (error);
  }
  
  /*
   * Receive data on a hook
   */
  static int
  ngs_rcvdata(hook_p hook, item_p item)
  {
  	struct ngsock *const priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
  	struct ngpcb *const pcbp = priv->datasock;
  	struct socket *so;
  	struct sockaddr_ng *addr;
  	char *addrbuf[NG_HOOKSIZ + 4];
  	int addrlen;
  	struct mbuf *m;
  
  	NGI_GET_M(item, m);
  	NG_FREE_ITEM(item);
  
  	/* If there is no data socket, black-hole it. */
  	if (pcbp == NULL) {
  		NG_FREE_M(m);
  		return (0);
  	}
  	so = pcbp->ng_socket;
  
  	/* Get the return address into a sockaddr. */
  	addrlen = strlen(NG_HOOK_NAME(hook));	/* <= NG_HOOKSIZ - 1 */
  	addr = (struct sockaddr_ng *) addrbuf;
  	addr->sg_len = addrlen + 3;
  	addr->sg_family = AF_NETGRAPH;
  	bcopy(NG_HOOK_NAME(hook), addr->sg_data, addrlen);
  	addr->sg_data[addrlen] = '\0';
  
  	/* Try to tell the socket which hook it came in on. */
  	lwkt_gettoken(&so->so_rcv.ssb_token);
  	if (sbappendaddr((struct sockbuf *)&so->so_rcv, (struct sockaddr *)addr, m, NULL) == 0) {
  		lwkt_reltoken(&so->so_rcv.ssb_token);
  		m_freem(m);
  		TRAP_ERROR;
  		return (ENOBUFS);
  	}
  	lwkt_reltoken(&so->so_rcv.ssb_token);
  	sorwakeup(so);
  	return (0);
  }
  
  /*
   * Hook disconnection
   *
   * For this type, removal of the last link destroys the node
   * if the NOLINGER flag is set.
   */
  static int
  ngs_disconnect(hook_p hook)
  {
  	node_p node = NG_HOOK_NODE(hook);
  	struct ngsock *const priv = NG_NODE_PRIVATE(node);
  
  	if ((priv->datasock) && (priv->datasock->ng_socket)) {
  		if (NG_NODE_NUMHOOKS(node) == 1)
  			sosetstate(priv->datasock->ng_socket, SS_ISCONNECTED);
  		else
  			soclrstate(priv->datasock->ng_socket, SS_ISCONNECTED);
  	}
  
  	if ((priv->flags & NGS_FLAG_NOLINGER) &&
  	    (NG_NODE_NUMHOOKS(node) == 0) && (NG_NODE_IS_VALID(node)))
  		ng_rmnode_self(node);
  
  	return (0);
  }
  
  /*
   * Do local shutdown processing.
   * In this case, that involves making sure the socket
   * knows we should be shutting down.
   */
  static int
  ngs_shutdown(node_p node)
  {
  	struct ngsock *const priv = NG_NODE_PRIVATE(node);
  	struct ngpcb *const dpcbp = priv->datasock;
  	struct ngpcb *const pcbp = priv->ctlsock;
  
  	if (dpcbp != NULL)
  		soisdisconnected(dpcbp->ng_socket);
  
  	if (pcbp != NULL)
  		soisdisconnected(pcbp->ng_socket);
  
  	mtx_lock(&priv->mtx);
  	priv->node = NULL;
  	NG_NODE_SET_PRIVATE(node, NULL);
  	ng_socket_free_priv(priv);
  
  	NG_NODE_UNREF(node);
  	return (0);
  }
  
  static void
  ng_socket_item_applied(void *context, int error)
  {
  	lwkt_msg *msg = context;
   
  	lwkt_replymsg(msg, error);
  }
  
  /*
   * Control and data socket type descriptors
   *
   * XXXRW: Perhaps _close should do something?
   */
  
  static struct pr_usrreqs ngc_usrreqs = {
  	.pru_abort =		NULL,
  	.pru_attach =		ngc_attach,
  	.pru_bind =		ngc_bind,
  	.pru_connect =		ngc_connect,
  	.pru_detach =		ngc_detach,
  	.pru_disconnect =	NULL,
  	.pru_peeraddr =		NULL,
  	.pru_send =		ngc_send,
  	.pru_shutdown =		NULL,
  	.pru_sockaddr =		ng_getsockaddr,
  	.pru_sosend =		sosend,
  	.pru_soreceive =	soreceive,
  	/* .pru_close =		NULL, */
  };
  
  static struct pr_usrreqs ngd_usrreqs = {
  	.pru_abort =		NULL,
  	.pru_attach =		ngd_attach,
  	.pru_bind =		NULL,
  	.pru_connect =		ngd_connect,
  	.pru_detach =		ngd_detach,
  	.pru_disconnect =	NULL,
  	.pru_peeraddr =		NULL,
  	.pru_send =		ngd_send,
  	.pru_shutdown =		NULL,
  	.pru_sockaddr =		ng_getsockaddr,
  	.pru_sosend =		sosend,
  	.pru_soreceive =	soreceive,
  	/* .pru_close =		NULL, */
  };
  
  /*
   * Definitions of protocols supported in the NETGRAPH domain.
   */
  
  extern struct domain ngdomain;		/* stop compiler warnings */
  
  static struct protosw ngsw[] = {
  {
  	.pr_type =		SOCK_DGRAM,
  	.pr_domain =		&ngdomain,
  	.pr_protocol =		NG_CONTROL,
  	.pr_flags =		PR_ATOMIC | PR_ADDR /* | PR_RIGHTS */,
  	.pr_usrreqs =		&ngc_usrreqs
  },
  {
  	.pr_type =		SOCK_DGRAM,
  	.pr_domain =		&ngdomain,
  	.pr_protocol =		NG_DATA,
  	.pr_flags =		PR_ATOMIC | PR_ADDR,
  	.pr_usrreqs =		&ngd_usrreqs
  }
  };
  
  struct domain ngdomain = {
  	.dom_family =		AF_NETGRAPH,
  	.dom_name =		"netgraph",
  	.dom_protosw =		ngsw,
  	.dom_protoswNPROTOSW =	&ngsw[NELEM(ngsw)]
  };
  
  /*
   * Handle loading and unloading for this node type.
   * This is to handle auxiliary linkages (e.g protocol domain addition).
   */
  static int
  ngs_mod_event(module_t mod, int event, void *data)
  {
  	int error = 0;
  
  	switch (event) {
  	case MOD_LOAD:
  		/* Register protocol domain. */
  		net_add_domain(&ngdomain);
  		break;
  	case MOD_UNLOAD:
  #ifdef NOTYET
  		/* Unregister protocol domain XXX can't do this yet.. */
  		if ((error = net_rm_domain(&ngdomain)) != 0)
  			break;
  		else
  #endif
  			error = EBUSY;
  		break;
  	default:
  		error = EOPNOTSUPP;
  		break;
  	}
  	return (error);
  }
  
  static int
  linker_api_available(void)
  {
  	/* linker_* API won't work without a process context */
  	if (curproc == NULL)
  		return 0;
  	/*
  	 * nlookup_init() relies on namei_oc to be initialized,
  	 * but it's not when the netgraph module is loaded during boot.
  	 */
  	if (namei_oc == NULL)
  		return 0;
  	return 1;
  }
  
  SYSCTL_INT(_net_graph, OID_AUTO, family, CTLFLAG_RD, 0, AF_NETGRAPH, "");
  SYSCTL_NODE(_net_graph, OID_AUTO, data, CTLFLAG_RW, 0, "DATA");
  SYSCTL_INT(_net_graph_data, OID_AUTO, proto, CTLFLAG_RD, 0, NG_DATA, "");
  SYSCTL_NODE(_net_graph, OID_AUTO, control, CTLFLAG_RW, 0, "CONTROL");
  SYSCTL_INT(_net_graph_control, OID_AUTO, proto, CTLFLAG_RD, 0, NG_CONTROL, "");
  
  