text: 
  /*
   * ng_tee.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@whistle.com>
   *
   * $FreeBSD: src/sys/netgraph/ng_tee.c,v 1.4.2.4 1999/12/03 07:44:24 julian Exp $
   * $Whistle: ng_tee.c,v 1.18 1999/11/01 09:24:52 julian Exp $
   */
  
  /*
   * This node is like the tee(1) command and is useful for ``snooping.''
   * It has 4 hooks: left, right, left2right, and right2left. Data
   * entering from the right is passed to the left and duplicated on
   * right2left, and data entering from the left is passed to the right
   * and duplicated on left2right. Data entering from left2right is
   * sent to right, and data from right2left to left.
   */
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/errno.h>
  #include <sys/kernel.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <netgraph/ng_message.h>
  #include <netgraph/netgraph.h>
  #include <netgraph/ng_tee.h>
  
  /* Per hook info */
  struct hookinfo {
  	hook_p			hook;
  	struct ng_tee_hookstat	stats;
  };
  
  /* Per node info */
  struct privdata {
  	node_p			node;
  	struct hookinfo		left;
  	struct hookinfo		right;
  	struct hookinfo		left2right;
  	struct hookinfo		right2left;
  };
  typedef struct privdata *sc_p;
  
  /* Netgraph methods */
  static ng_constructor_t	ngt_constructor;
  static ng_rcvmsg_t	ngt_rcvmsg;
  static ng_shutdown_t	ngt_rmnode;
  static ng_newhook_t	ngt_newhook;
  static ng_rcvdata_t	ngt_rcvdata;
  static ng_disconnect_t	ngt_disconnect;
  
  /* Netgraph type descriptor */
  static struct ng_type typestruct = {
  	NG_VERSION,
  	NG_TEE_NODE_TYPE,
  	NULL,
  	ngt_constructor,
  	ngt_rcvmsg,
  	ngt_rmnode,
  	ngt_newhook,
  	NULL,
  	NULL,
  	ngt_rcvdata,
  	ngt_rcvdata,
  	ngt_disconnect,
  	NULL
  };
  NETGRAPH_INIT(tee, &typestruct);
  
  /*
   * Node constructor
   */
  static int
  ngt_constructor(node_p *nodep)
  {
  	sc_p privdata;
  	int error = 0;
  
  	MALLOC(privdata, sc_p, sizeof(*privdata), M_NETGRAPH, M_WAITOK);
  	if (privdata == NULL)
  		return (ENOMEM);
  	bzero(privdata, sizeof(*privdata));
  
  	if ((error = ng_make_node_common(&typestruct, nodep))) {
  		FREE(privdata, M_NETGRAPH);
  		return (error);
  	}
  	(*nodep)->private = privdata;
  	privdata->node = *nodep;
  	return (0);
  }
  
  /*
   * Add a hook
   */
  static int
  ngt_newhook(node_p node, hook_p hook, const char *name)
  {
  	const sc_p sc = node->private;
  
  	if (strcmp(name, NG_TEE_HOOK_RIGHT) == 0) {
  		sc->right.hook = hook;
  		bzero(&sc->right.stats, sizeof(sc->right.stats));
  		hook->private = &sc->right;
  	} else if (strcmp(name, NG_TEE_HOOK_LEFT) == 0) {
  		sc->left.hook = hook;
  		bzero(&sc->left.stats, sizeof(sc->left.stats));
  		hook->private = &sc->left;
  	} else if (strcmp(name, NG_TEE_HOOK_RIGHT2LEFT) == 0) {
  		sc->right2left.hook = hook;
  		bzero(&sc->right2left.stats, sizeof(sc->right2left.stats));
  		hook->private = &sc->right2left;
  	} else if (strcmp(name, NG_TEE_HOOK_LEFT2RIGHT) == 0) {
  		sc->left2right.hook = hook;
  		bzero(&sc->left2right.stats, sizeof(sc->left2right.stats));
  		hook->private = &sc->left2right;
  	} else
  		return (EINVAL);
  	return (0);
  }
  
  /*
   * Receive a control message
   */
  static int
  ngt_rcvmsg(node_p node, struct ng_mesg *msg, const char *retaddr,
  	   struct ng_mesg **rptr)
  {
  	const sc_p sc = node->private;
  	struct ng_mesg *resp = NULL;
  	int error = 0;
  
  	switch (msg->header.typecookie) {
  	case NGM_TEE_COOKIE:
  		switch (msg->header.cmd) {
  		case NGM_TEE_GET_STATS:
  		    {
  			struct ng_tee_stats *stats;
  
  			NG_MKRESPONSE(resp, msg,
  			    sizeof(struct ng_tee_stats), M_NOWAIT);
  			if (resp == NULL) {
  				error = ENOMEM;
  				goto done;
  			}
  			stats = (struct ng_tee_stats *) resp->data;
  			bcopy(&sc->right.stats,
  			    &stats->right, sizeof(stats->right));
  			bcopy(&sc->left.stats,
  			    &stats->left, sizeof(stats->left));
  			bcopy(&sc->right2left.stats,
  			    &stats->right2left, sizeof(stats->right2left));
  			bcopy(&sc->left2right.stats,
  			    &stats->left2right, sizeof(stats->left2right));
  			break;
  		    }
  		case NGM_TEE_CLR_STATS:
  			bzero(&sc->right.stats, sizeof(sc->right.stats));
  			bzero(&sc->left.stats, sizeof(sc->left.stats));
  			bzero(&sc->right2left.stats,
  			    sizeof(sc->right2left.stats));
  			bzero(&sc->left2right.stats,
  			    sizeof(sc->left2right.stats));
  			break;
  		default:
  			error = EINVAL;
  			break;
  		}
  		break;
  	default:
  		error = EINVAL;
  		break;
  	}
  	if (rptr)
  		*rptr = resp;
  	else if (resp)
  		FREE(resp, M_NETGRAPH);
  
  done:
  	FREE(msg, M_NETGRAPH);
  	return (error);
  }
  
  /*
   * Receive data on a hook
   *
   * If data comes in the right link send a copy out right2left, and then
   * send the original onwards out through the left link.
   * Do the opposite for data coming in from the left link.
   * Data coming in right2left or left2right is forwarded
   * on through the appropriate destination hook as if it had come
   * from the other side.
   */
  static int
  ngt_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
  {
  	const sc_p sc = hook->node->private;
  	struct hookinfo *const hinfo = (struct hookinfo *) hook->private;
  	struct hookinfo *dest;
  	struct hookinfo *dup;
  	int error = 0;
  
  	/* Which hook? */
  	if (hinfo == &sc->left) {
  		dup = &sc->left2right;
  		dest = &sc->right;
  	} else if (hinfo == &sc->right) {
  		dup = &sc->right2left;
  		dest = &sc->left;
  	} else if (hinfo == &sc->right2left) {
  		dup = NULL;
  		dest = &sc->left;
  	} else if (hinfo == &sc->left2right) {
  		dup = NULL;
  		dest = &sc->right;
  	} else
  		panic("%s: no hook!", __FUNCTION__);
  
  	/* Update stats on incoming hook */
  	hinfo->stats.inOctets += m->m_pkthdr.len;
  	hinfo->stats.inFrames++;
  
  	/* Duplicate packet and meta info if requried */
  	if (dup != NULL) {
  		struct mbuf *m2;
  		meta_p meta2;
  
  		/* Copy packet */
  		m2 = m_dup(m, M_NOWAIT);
  		if (m2 == NULL) {
  			NG_FREE_DATA(m, meta);
  			return (ENOBUFS);
  		}
  
  		/* Copy meta info */
  		if (meta != NULL) {
  			MALLOC(meta2, meta_p,
  			    meta->used_len, M_NETGRAPH, M_NOWAIT);
  			if (meta2 == NULL) {
  				m_freem(m2);
  				NG_FREE_DATA(m, meta);
  				return (ENOMEM);
  			}
  			bcopy(meta, meta2, meta->used_len);
  			meta2->allocated_len = meta->used_len;
  		} else
  			meta2 = NULL;
  
  		/* Deliver duplicate */
  		dup->stats.outOctets += m->m_pkthdr.len;
  		dup->stats.outFrames++;
  		NG_SEND_DATA(error, dup->hook, m2, meta2);
  	}
  
  	/* Deliver frame out destination hook */
  	dest->stats.outOctets += m->m_pkthdr.len;
  	dest->stats.outFrames++;
  	NG_SEND_DATA(error, dest->hook, m, meta);
  	return (0);
  }
  
  /*
   * Shutdown processing
   *
   * This is tricky. If we have both a left and right hook, then we
   * probably want to extricate ourselves and leave the two peers
   * still linked to each other. Otherwise we should just shut down as
   * a normal node would.
   *
   * To keep the scope of info correct the routine to "extract" a node
   * from two links is in ng_base.c.
   */
  static int
  ngt_rmnode(node_p node)
  {
  	const sc_p privdata = node->private;
  
  	node->flags |= NG_INVALID;
  	if (privdata->left.hook && privdata->right.hook)
  		ng_bypass(privdata->left.hook, privdata->right.hook);
  	ng_cutlinks(node);
  	ng_unname(node);
  	node->private = NULL;
  	ng_unref(privdata->node);
  	FREE(privdata, M_NETGRAPH);
  	return (0);
  }
  
  /*
   * Hook disconnection
   */
  static int
  ngt_disconnect(hook_p hook)
  {
  	struct hookinfo *const hinfo = (struct hookinfo *) hook->private;
  
  	KASSERT(hinfo != NULL, ("%s: null info", __FUNCTION__));
  	hinfo->hook = NULL;
  	if (hook->node->numhooks == 0)
  		ng_rmnode(hook->node);
  	return (0);
  }
  
  