text: /*
   * ng_ether_echo.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 Elisher <julian@freebsd.org>
   *
   * $FreeBSD: soc2013/dpl/head/sys/netgraph/ng_ether_echo.c 186524 2008-12-25 00:01:29Z julian $
   * $Whistle: ng_echo.c,v 1.13 1999/11/01 09:24:51 julian Exp $
   */
  
  /*
   * Netgraph "ether_echo" node
   *
   * This node simply bounces data and messages back to whence they came.
   * However it swaps the source and destination ether fields.
   * No testing is done!
   */
  
  #include <sys/param.h>
  #include <sys/systm.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_ether_echo.h>
  
  #include <net/ethernet.h>
  
  /* Netgraph methods */
  static ng_constructor_t	ngee_cons;
  static ng_rcvmsg_t	ngee_rcvmsg;
  static ng_rcvdata_t	ngee_rcvdata;
  static ng_disconnect_t	ngee_disconnect;
  
  /* Netgraph type */
  static struct ng_type typestruct = {
  	.version =	NG_ABI_VERSION,
  	.name =		NG_ETHER_ECHO_NODE_TYPE,
  	.constructor =	ngee_cons,
  	.rcvmsg =	ngee_rcvmsg,
  	.rcvdata =	ngee_rcvdata,
  	.disconnect =	ngee_disconnect,
  };
  NETGRAPH_INIT(ether_echo, &typestruct);
  
  static int
  ngee_cons(node_p node)
  {
  	return (0);
  }
  
  /*
   * Receive control message. We just bounce it back as a reply.
   */
  static int
  ngee_rcvmsg(node_p node, item_p item, hook_p lasthook)
  {
  	struct ng_mesg *msg;
  	int error = 0;
  
  	NGI_GET_MSG(item, msg);
  	msg->header.flags |= NGF_RESP;
  	NG_RESPOND_MSG(error, node, item, msg);
  	return (error);
  }
  
  /*
   * Receive data
   */
  static int
  ngee_rcvdata(hook_p hook, item_p item)
  {
  	int error;
  	struct mbuf *m;
  
  	struct ether_header *eh;
  	struct ether_addr tmpaddr;
  
  	/* Make sure we have an entire header */
  	NGI_GET_M(item, m);
  	if (m->m_len < sizeof(*eh) ) {
  		m = m_pullup(m, sizeof(*eh));
  		if (m == NULL) {
  			NG_FREE_ITEM(item);
  			return(EINVAL);
  		}
  	}
  	eh = mtod(m, struct ether_header *);
  
  	/* swap the source and destination fields */
  	bcopy(eh->ether_dhost, &tmpaddr, ETHER_ADDR_LEN);
  	bcopy(eh->ether_shost, eh->ether_dhost, ETHER_ADDR_LEN);
  	bcopy(&tmpaddr, eh->ether_shost, ETHER_ADDR_LEN);
  
  	NG_FWD_NEW_DATA(error, item, hook, m);
  	return (error);
  }
  
  /*
   * Removal of the last link destroys the nodeo
   */
  static int
  ngee_disconnect(hook_p hook)
  {
  	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
  	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
  		ng_rmnode_self(NG_HOOK_NODE(hook));
  	}
  	return (0);
  }
  
  