FreeBSD/Linux Kernel Cross Reference
sys/net/if_disc.c

     /*
      * Copyright (c) 1982, 1986, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON 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 ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     *      From: @(#)if_loop.c     8.1 (Berkeley) 6/10/93
     * $FreeBSD$
     */
    
    /*
     * Discard interface driver for protocol testing and timing.
     * (Based on the loopback.)
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/kernel.h>
    #include <sys/mbuf.h>
    #include <sys/socket.h>
    #include <sys/sockio.h>
    
    #include <net/if.h>
    #include <net/if_types.h>
    #include <net/route.h>
    #include <net/bpf.h>
    
    #include "bpfilter.h"
    #include "opt_inet.h"
    
    #ifdef TINY_DSMTU
    #define DSMTU   (1024+512)
    #else
    #define DSMTU   65532
    #endif
    
    static void discattach __P((void *dummy));
    PSEUDO_SET(discattach, if_disc);
    
    static struct   ifnet discif;
    static int discoutput(struct ifnet *, struct mbuf *, struct sockaddr *,
                        struct rtentry *);
    static void discrtrequest(int cmd, struct rtentry *rt, struct sockaddr *sa);
    static int discioctl(struct ifnet *, u_long, caddr_t);
    
    /* ARGSUSED */
    static void
    discattach(dummy)
            void *dummy;
    {
            register struct ifnet *ifp = &discif;
    
            ifp->if_name = "ds";
            ifp->if_mtu = DSMTU;
            ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
            ifp->if_ioctl = discioctl;
            ifp->if_output = discoutput;
            ifp->if_type = IFT_LOOP;
            ifp->if_hdrlen = 0;
            ifp->if_addrlen = 0;
            if_attach(ifp);
    #if NBPFILTER > 0
            bpfattach(ifp, DLT_NULL, sizeof(u_int));
    #endif
    }
    
    static int
    discoutput(ifp, m, dst, rt)
            struct ifnet *ifp;
            register struct mbuf *m;
            struct sockaddr *dst;
            register struct rtentry *rt;
    {
           if ((m->m_flags & M_PKTHDR) == 0)
                   panic("discoutput no HDR");
   #if NBPFILTER > 0
           /* BPF write needs to be handled specially */
           if (dst->sa_family == AF_UNSPEC) {
                   dst->sa_family = *(mtod(m, int *));
                   m->m_len -= sizeof(int);
                   m->m_pkthdr.len -= sizeof(int);
                   m->m_data += sizeof(int);
           }
   
           if (discif.if_bpf) {
                   /*
                    * We need to prepend the address family as
                    * a four byte field.  Cons up a dummy header
                    * to pacify bpf.  This is safe because bpf
                    * will only read from the mbuf (i.e., it won't
                    * try to free it or keep a pointer a to it).
                    */
                   struct mbuf m0;
                   u_int af = dst->sa_family;
   
                   m0.m_next = m;
                   m0.m_len = 4;
                   m0.m_data = (char *)&af;
   
                   bpf_mtap(&discif, &m0);
           }
   #endif
           m->m_pkthdr.rcvif = ifp;
   
           ifp->if_opackets++;
           ifp->if_obytes += m->m_pkthdr.len;
   
           m_freem(m);
           return 0;
   }
   
   /* ARGSUSED */
   static void
   discrtrequest(cmd, rt, sa)
           int cmd;
           struct rtentry *rt;
           struct sockaddr *sa;
   {
           if (rt)
                   rt->rt_rmx.rmx_mtu = DSMTU;
   }
   
   /*
    * Process an ioctl request.
    */
   /* ARGSUSED */
   static int
   discioctl(ifp, cmd, data)
           register struct ifnet *ifp;
           u_long cmd;
           caddr_t data;
   {
           register struct ifaddr *ifa;
           register struct ifreq *ifr = (struct ifreq *)data;
           register int error = 0;
   
           switch (cmd) {
   
           case SIOCSIFADDR:
                   ifp->if_flags |= IFF_UP;
                   ifa = (struct ifaddr *)data;
                   if (ifa != 0)
                           ifa->ifa_rtrequest = discrtrequest;
                   /*
                    * Everything else is done at a higher level.
                    */
                   break;
   
           case SIOCADDMULTI:
           case SIOCDELMULTI:
                   if (ifr == 0) {
                           error = EAFNOSUPPORT;           /* XXX */
                           break;
                   }
                   switch (ifr->ifr_addr.sa_family) {
   
   #ifdef INET
                   case AF_INET:
                           break;
   #endif
   
                   default:
                           error = EAFNOSUPPORT;
                           break;
                   }
                   break;
   
           case SIOCSIFMTU:
                   ifp->if_mtu = ifr->ifr_mtu;
                   break;
   
           default:
                   error = EINVAL;
           }
           return (error);
   }

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