The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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

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    1 /*
    2  * Copyright (c) 1982, 1986, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1. Redistributions of source code must retain the above copyright
    9  *    notice, this list of conditions and the following disclaimer.
   10  * 2. Redistributions in binary form must reproduce the above copyright
   11  *    notice, this list of conditions and the following disclaimer in the
   12  *    documentation and/or other materials provided with the distribution.
   13  * 3. All advertising materials mentioning features or use of this software
   14  *    must display the following acknowledgement:
   15  *      This product includes software developed by the University of
   16  *      California, Berkeley and its contributors.
   17  * 4. Neither the name of the University nor the names of its contributors
   18  *    may be used to endorse or promote products derived from this software
   19  *    without specific prior written permission.
   20  *
   21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   31  * SUCH DAMAGE.
   32  *
   33  *      @(#)if_loop.c   8.2 (Berkeley) 1/9/95
   34  * $FreeBSD: releng/5.2/sys/net/if_loop.c 122922 2003-11-20 20:07:39Z andre $
   35  */
   36 
   37 /*
   38  * Loopback interface driver for protocol testing and timing.
   39  */
   40 
   41 #include "opt_atalk.h"
   42 #include "opt_inet.h"
   43 #include "opt_inet6.h"
   44 #include "opt_ipx.h"
   45 #include "opt_mac.h"
   46 
   47 #include <sys/param.h>
   48 #include <sys/systm.h>
   49 #include <sys/kernel.h>
   50 #include <sys/mac.h>
   51 #include <sys/malloc.h>
   52 #include <sys/mbuf.h>
   53 #include <sys/module.h>
   54 #include <machine/bus.h>
   55 #include <sys/rman.h>
   56 #include <sys/socket.h>
   57 #include <sys/sockio.h>
   58 #include <sys/sysctl.h>
   59 
   60 #include <net/if.h>
   61 #include <net/if_types.h>
   62 #include <net/netisr.h>
   63 #include <net/route.h>
   64 #include <net/bpf.h>
   65 #include <net/bpfdesc.h>
   66 
   67 #ifdef  INET
   68 #include <netinet/in.h>
   69 #include <netinet/in_var.h>
   70 #endif
   71 
   72 #ifdef IPX
   73 #include <netipx/ipx.h>
   74 #include <netipx/ipx_if.h>
   75 #endif
   76 
   77 #ifdef INET6
   78 #ifndef INET
   79 #include <netinet/in.h>
   80 #endif
   81 #include <netinet6/in6_var.h>
   82 #include <netinet/ip6.h>
   83 #endif
   84 
   85 #ifdef NETATALK
   86 #include <netatalk/at.h>
   87 #include <netatalk/at_var.h>
   88 #endif
   89 
   90 #ifdef TINY_LOMTU
   91 #define LOMTU   (1024+512)
   92 #elif defined(LARGE_LOMTU)
   93 #define LOMTU   131072
   94 #else
   95 #define LOMTU   16384
   96 #endif
   97 
   98 #define LONAME  "lo"
   99 
  100 struct lo_softc {
  101         struct  ifnet sc_if;            /* network-visible interface */
  102         LIST_ENTRY(lo_softc) sc_next;
  103 };
  104 
  105 int             loioctl(struct ifnet *, u_long, caddr_t);
  106 static void     lortrequest(int, struct rtentry *, struct rt_addrinfo *);
  107 int             looutput(struct ifnet *ifp, struct mbuf *m,
  108                     struct sockaddr *dst, struct rtentry *rt);
  109 int             lo_clone_create(struct if_clone *, int);
  110 void            lo_clone_destroy(struct ifnet *);
  111 
  112 struct ifnet *loif = NULL;                      /* Used externally */
  113 
  114 static MALLOC_DEFINE(M_LO, LONAME, "Loopback Interface");
  115 
  116 static LIST_HEAD(lo_list, lo_softc) lo_list;
  117 
  118 struct if_clone lo_cloner = IF_CLONE_INITIALIZER(LONAME,
  119     lo_clone_create, lo_clone_destroy, 1, IF_MAXUNIT);
  120 
  121 void
  122 lo_clone_destroy(ifp)
  123         struct ifnet *ifp;
  124 {
  125         struct lo_softc *sc;
  126         
  127         sc = ifp->if_softc;
  128 
  129         /* XXX: destroying lo0 will lead to panics. */
  130         KASSERT(loif != ifp, ("%s: destroying lo0", __func__));
  131 
  132         bpfdetach(ifp);
  133         if_detach(ifp);
  134         LIST_REMOVE(sc, sc_next);
  135         free(sc, M_LO);
  136 }
  137 
  138 int
  139 lo_clone_create(ifc, unit)
  140         struct if_clone *ifc;
  141         int unit;
  142 {
  143         struct lo_softc *sc;
  144 
  145         MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
  146 
  147         if_initname(&sc->sc_if, ifc->ifc_name, unit);
  148         sc->sc_if.if_mtu = LOMTU;
  149         sc->sc_if.if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  150         sc->sc_if.if_ioctl = loioctl;
  151         sc->sc_if.if_output = looutput;
  152         sc->sc_if.if_type = IFT_LOOP;
  153         sc->sc_if.if_snd.ifq_maxlen = ifqmaxlen;
  154         sc->sc_if.if_softc = sc;
  155         if_attach(&sc->sc_if);
  156         bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
  157         LIST_INSERT_HEAD(&lo_list, sc, sc_next);
  158         if (loif == NULL)
  159                 loif = &sc->sc_if;
  160 
  161         return (0);
  162 }
  163 
  164 static int
  165 loop_modevent(module_t mod, int type, void *data) 
  166 { 
  167         switch (type) { 
  168         case MOD_LOAD: 
  169                 LIST_INIT(&lo_list);
  170                 if_clone_attach(&lo_cloner);
  171                 break; 
  172         case MOD_UNLOAD: 
  173                 printf("loop module unload - not possible for this module type\n"); 
  174                 return EINVAL; 
  175         } 
  176         return 0; 
  177 } 
  178 
  179 static moduledata_t loop_mod = { 
  180         "loop", 
  181         loop_modevent, 
  182         0
  183 }; 
  184 
  185 DECLARE_MODULE(loop, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  186 
  187 int
  188 looutput(ifp, m, dst, rt)
  189         struct ifnet *ifp;
  190         register struct mbuf *m;
  191         struct sockaddr *dst;
  192         register struct rtentry *rt;
  193 {
  194         M_ASSERTPKTHDR(m); /* check if we have the packet header */
  195 
  196         if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  197                 m_freem(m);
  198                 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  199                         rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  200         }
  201 
  202         ifp->if_opackets++;
  203         ifp->if_obytes += m->m_pkthdr.len;
  204 #if 1   /* XXX */
  205         switch (dst->sa_family) {
  206         case AF_INET:
  207         case AF_INET6:
  208         case AF_IPX:
  209         case AF_APPLETALK:
  210                 break;
  211         default:
  212                 printf("looutput: af=%d unexpected\n", dst->sa_family);
  213                 m_freem(m);
  214                 return (EAFNOSUPPORT);
  215         }
  216 #endif
  217         return(if_simloop(ifp, m, dst->sa_family, 0));
  218 }
  219 
  220 /*
  221  * if_simloop()
  222  *
  223  * This function is to support software emulation of hardware loopback,
  224  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
  225  * hear their own broadcasts, we create a copy of the packet that we
  226  * would normally receive via a hardware loopback.
  227  *
  228  * This function expects the packet to include the media header of length hlen.
  229  */
  230 
  231 int
  232 if_simloop(ifp, m, af, hlen)
  233         struct ifnet *ifp;
  234         struct mbuf *m;
  235         int af;
  236         int hlen;
  237 {
  238         int isr;
  239 
  240         M_ASSERTPKTHDR(m);
  241         m_tag_delete_nonpersistent(m);
  242         m->m_pkthdr.rcvif = ifp;
  243 
  244         /* BPF write needs to be handled specially */
  245         if (af == AF_UNSPEC) {
  246                 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
  247                 af = *(mtod(m, int *));
  248                 m->m_len -= sizeof(int);
  249                 m->m_pkthdr.len -= sizeof(int);
  250                 m->m_data += sizeof(int);
  251         }
  252 
  253         /* Let BPF see incoming packet */
  254         if (ifp->if_bpf) {
  255                 struct mbuf m0, *n = m;
  256 
  257                 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
  258                         /*
  259                          * We need to prepend the address family as
  260                          * a four byte field.  Cons up a dummy header
  261                          * to pacify bpf.  This is safe because bpf
  262                          * will only read from the mbuf (i.e., it won't
  263                          * try to free it or keep a pointer a to it).
  264                          */
  265                         m0.m_next = m;
  266                         m0.m_len = 4;
  267                         m0.m_data = (char *)&af;
  268                         n = &m0;
  269                 }
  270                 BPF_MTAP(ifp, n);
  271         }
  272 
  273         /* Strip away media header */
  274         if (hlen > 0) {
  275                 m_adj(m, hlen);
  276 #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
  277                 /* The alpha doesn't like unaligned data.
  278                  * We move data down in the first mbuf */
  279                 if (mtod(m, vm_offset_t) & 3) {
  280                         KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  281                         bcopy(m->m_data, 
  282                             (char *)(mtod(m, vm_offset_t) 
  283                                 - (mtod(m, vm_offset_t) & 3)),
  284                             m->m_len);
  285                         mtod(m,vm_offset_t) -= (mtod(m, vm_offset_t) & 3);
  286                 }
  287 #endif
  288         }
  289 
  290         /* Deliver to upper layer protocol */
  291         switch (af) {
  292 #ifdef INET
  293         case AF_INET:
  294                 isr = NETISR_IP;
  295                 break;
  296 #endif
  297 #ifdef INET6
  298         case AF_INET6:
  299                 m->m_flags |= M_LOOP;
  300                 isr = NETISR_IPV6;
  301                 break;
  302 #endif
  303 #ifdef IPX
  304         case AF_IPX:
  305                 isr = NETISR_IPX;
  306                 break;
  307 #endif
  308 #ifdef NETATALK
  309         case AF_APPLETALK:
  310                 isr = NETISR_ATALK2;
  311                 break;
  312 #endif
  313         default:
  314                 printf("if_simloop: can't handle af=%d\n", af);
  315                 m_freem(m);
  316                 return (EAFNOSUPPORT);
  317         }
  318         ifp->if_ipackets++;
  319         ifp->if_ibytes += m->m_pkthdr.len;
  320         netisr_queue(isr, m);
  321         return (0);
  322 }
  323 
  324 /* ARGSUSED */
  325 static void
  326 lortrequest(cmd, rt, info)
  327         int cmd;
  328         struct rtentry *rt;
  329         struct rt_addrinfo *info;
  330 {
  331         RT_LOCK_ASSERT(rt);
  332         if (rt)
  333                 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  334 }
  335 
  336 /*
  337  * Process an ioctl request.
  338  */
  339 /* ARGSUSED */
  340 int
  341 loioctl(ifp, cmd, data)
  342         register struct ifnet *ifp;
  343         u_long cmd;
  344         caddr_t data;
  345 {
  346         register struct ifaddr *ifa;
  347         register struct ifreq *ifr = (struct ifreq *)data;
  348         register int error = 0;
  349 
  350         switch (cmd) {
  351 
  352         case SIOCSIFADDR:
  353                 ifp->if_flags |= IFF_UP | IFF_RUNNING;
  354                 ifa = (struct ifaddr *)data;
  355                 ifa->ifa_rtrequest = lortrequest;
  356                 /*
  357                  * Everything else is done at a higher level.
  358                  */
  359                 break;
  360 
  361         case SIOCADDMULTI:
  362         case SIOCDELMULTI:
  363                 if (ifr == 0) {
  364                         error = EAFNOSUPPORT;           /* XXX */
  365                         break;
  366                 }
  367                 switch (ifr->ifr_addr.sa_family) {
  368 
  369 #ifdef INET
  370                 case AF_INET:
  371                         break;
  372 #endif
  373 #ifdef INET6
  374                 case AF_INET6:
  375                         break;
  376 #endif
  377 
  378                 default:
  379                         error = EAFNOSUPPORT;
  380                         break;
  381                 }
  382                 break;
  383 
  384         case SIOCSIFMTU:
  385                 ifp->if_mtu = ifr->ifr_mtu;
  386                 break;
  387 
  388         case SIOCSIFFLAGS:
  389                 break;
  390 
  391         default:
  392                 error = EINVAL;
  393         }
  394         return (error);
  395 }

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