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  * 4. Neither the name of the University nor the names of its contributors
   14  *    may be used to endorse or promote products derived from this software
   15  *    without specific prior written permission.
   16  *
   17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   27  * SUCH DAMAGE.
   28  *
   29  *      @(#)if_loop.c   8.2 (Berkeley) 1/9/95
   30  * $FreeBSD: src/sys/net/if_loop.c,v 1.101.2.2 2005/01/31 23:26:23 imp Exp $
   31  */
   32 
   33 /*
   34  * Loopback interface driver for protocol testing and timing.
   35  */
   36 
   37 #include "opt_atalk.h"
   38 #include "opt_inet.h"
   39 #include "opt_inet6.h"
   40 #include "opt_ipx.h"
   41 
   42 #include <sys/param.h>
   43 #include <sys/systm.h>
   44 #include <sys/kernel.h>
   45 #include <sys/malloc.h>
   46 #include <sys/mbuf.h>
   47 #include <sys/module.h>
   48 #include <machine/bus.h>
   49 #include <sys/rman.h>
   50 #include <sys/socket.h>
   51 #include <sys/sockio.h>
   52 #include <sys/sysctl.h>
   53 
   54 #include <net/if.h>
   55 #include <net/if_clone.h>
   56 #include <net/if_types.h>
   57 #include <net/netisr.h>
   58 #include <net/route.h>
   59 #include <net/bpf.h>
   60 #include <net/bpfdesc.h>
   61 
   62 #ifdef  INET
   63 #include <netinet/in.h>
   64 #include <netinet/in_var.h>
   65 #endif
   66 
   67 #ifdef IPX
   68 #include <netipx/ipx.h>
   69 #include <netipx/ipx_if.h>
   70 #endif
   71 
   72 #ifdef INET6
   73 #ifndef INET
   74 #include <netinet/in.h>
   75 #endif
   76 #include <netinet6/in6_var.h>
   77 #include <netinet/ip6.h>
   78 #endif
   79 
   80 #ifdef NETATALK
   81 #include <netatalk/at.h>
   82 #include <netatalk/at_var.h>
   83 #endif
   84 
   85 #ifdef TINY_LOMTU
   86 #define LOMTU   (1024+512)
   87 #elif defined(LARGE_LOMTU)
   88 #define LOMTU   131072
   89 #else
   90 #define LOMTU   16384
   91 #endif
   92 
   93 #define LONAME  "lo"
   94 
   95 struct lo_softc {
   96         struct  ifnet sc_if;            /* network-visible interface */
   97         LIST_ENTRY(lo_softc) sc_next;
   98 };
   99 
  100 int             loioctl(struct ifnet *, u_long, caddr_t);
  101 static void     lortrequest(int, struct rtentry *, struct rt_addrinfo *);
  102 int             looutput(struct ifnet *ifp, struct mbuf *m,
  103                     struct sockaddr *dst, struct rtentry *rt);
  104 static int      lo_clone_create(struct if_clone *, int);
  105 static void     lo_clone_destroy(struct ifnet *);
  106 
  107 struct ifnet *loif = NULL;                      /* Used externally */
  108 
  109 static MALLOC_DEFINE(M_LO, LONAME, "Loopback Interface");
  110 
  111 static struct mtx lo_mtx;
  112 static LIST_HEAD(lo_list, lo_softc) lo_list;
  113 
  114 IFC_SIMPLE_DECLARE(lo, 1);
  115 
  116 static void
  117 lo_clone_destroy(ifp)
  118         struct ifnet *ifp;
  119 {
  120         struct lo_softc *sc;
  121         
  122         sc = ifp->if_softc;
  123 
  124         /* XXX: destroying lo0 will lead to panics. */
  125         KASSERT(loif != ifp, ("%s: destroying lo0", __func__));
  126 
  127         mtx_lock(&lo_mtx);
  128         LIST_REMOVE(sc, sc_next);
  129         mtx_unlock(&lo_mtx);
  130         bpfdetach(ifp);
  131         if_detach(ifp);
  132         free(sc, M_LO);
  133 }
  134 
  135 static int
  136 lo_clone_create(ifc, unit)
  137         struct if_clone *ifc;
  138         int unit;
  139 {
  140         struct lo_softc *sc;
  141 
  142         MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
  143 
  144         if_initname(&sc->sc_if, ifc->ifc_name, unit);
  145         sc->sc_if.if_mtu = LOMTU;
  146         sc->sc_if.if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  147         sc->sc_if.if_ioctl = loioctl;
  148         sc->sc_if.if_output = looutput;
  149         sc->sc_if.if_type = IFT_LOOP;
  150         sc->sc_if.if_snd.ifq_maxlen = ifqmaxlen;
  151         sc->sc_if.if_softc = sc;
  152         if_attach(&sc->sc_if);
  153         bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
  154         mtx_lock(&lo_mtx);
  155         LIST_INSERT_HEAD(&lo_list, sc, sc_next);
  156         mtx_unlock(&lo_mtx);
  157         if (loif == NULL)
  158                 loif = &sc->sc_if;
  159 
  160         return (0);
  161 }
  162 
  163 static int
  164 loop_modevent(module_t mod, int type, void *data) 
  165 { 
  166         switch (type) { 
  167         case MOD_LOAD: 
  168                 mtx_init(&lo_mtx, "lo_mtx", NULL, MTX_DEF);
  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         default:
  176                 return EOPNOTSUPP;
  177         } 
  178         return 0; 
  179 } 
  180 
  181 static moduledata_t loop_mod = { 
  182         "loop", 
  183         loop_modevent, 
  184         0
  185 }; 
  186 
  187 DECLARE_MODULE(loop, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  188 
  189 int
  190 looutput(ifp, m, dst, rt)
  191         struct ifnet *ifp;
  192         register struct mbuf *m;
  193         struct sockaddr *dst;
  194         register struct rtentry *rt;
  195 {
  196         M_ASSERTPKTHDR(m); /* check if we have the packet header */
  197 
  198         if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  199                 m_freem(m);
  200                 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  201                         rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  202         }
  203 
  204         ifp->if_opackets++;
  205         ifp->if_obytes += m->m_pkthdr.len;
  206 #if 1   /* XXX */
  207         switch (dst->sa_family) {
  208         case AF_INET:
  209         case AF_INET6:
  210         case AF_IPX:
  211         case AF_APPLETALK:
  212                 break;
  213         default:
  214                 printf("looutput: af=%d unexpected\n", dst->sa_family);
  215                 m_freem(m);
  216                 return (EAFNOSUPPORT);
  217         }
  218 #endif
  219         return(if_simloop(ifp, m, dst->sa_family, 0));
  220 }
  221 
  222 /*
  223  * if_simloop()
  224  *
  225  * This function is to support software emulation of hardware loopback,
  226  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
  227  * hear their own broadcasts, we create a copy of the packet that we
  228  * would normally receive via a hardware loopback.
  229  *
  230  * This function expects the packet to include the media header of length hlen.
  231  */
  232 
  233 int
  234 if_simloop(ifp, m, af, hlen)
  235         struct ifnet *ifp;
  236         struct mbuf *m;
  237         int af;
  238         int hlen;
  239 {
  240         int isr;
  241 
  242         M_ASSERTPKTHDR(m);
  243         m_tag_delete_nonpersistent(m);
  244         m->m_pkthdr.rcvif = ifp;
  245 
  246         /* BPF write needs to be handled specially */
  247         if (af == AF_UNSPEC) {
  248                 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
  249                 af = *(mtod(m, int *));
  250                 m->m_len -= sizeof(int);
  251                 m->m_pkthdr.len -= sizeof(int);
  252                 m->m_data += sizeof(int);
  253         }
  254 
  255         /* Let BPF see incoming packet */
  256         if (ifp->if_bpf) {
  257                 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
  258                         u_int32_t af1 = af;     /* XXX beware sizeof(af) != 4 */
  259                         /*
  260                          * We need to prepend the address family.
  261                          */
  262                         bpf_mtap2(ifp->if_bpf, &af1, sizeof(af1), m);
  263                 } else
  264                         bpf_mtap(ifp->if_bpf, m);
  265         }
  266 
  267         /* Strip away media header */
  268         if (hlen > 0) {
  269                 m_adj(m, hlen);
  270 #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
  271                 /* The alpha doesn't like unaligned data.
  272                  * We move data down in the first mbuf */
  273                 if (mtod(m, vm_offset_t) & 3) {
  274                         KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  275                         bcopy(m->m_data, 
  276                             (char *)(mtod(m, vm_offset_t) 
  277                                 - (mtod(m, vm_offset_t) & 3)),
  278                             m->m_len);
  279                         m->m_data -= (mtod(m,vm_offset_t) & 3);
  280                 }
  281 #endif
  282         }
  283 
  284         /* Deliver to upper layer protocol */
  285         switch (af) {
  286 #ifdef INET
  287         case AF_INET:
  288                 isr = NETISR_IP;
  289                 break;
  290 #endif
  291 #ifdef INET6
  292         case AF_INET6:
  293                 m->m_flags |= M_LOOP;
  294                 isr = NETISR_IPV6;
  295                 break;
  296 #endif
  297 #ifdef IPX
  298         case AF_IPX:
  299                 isr = NETISR_IPX;
  300                 break;
  301 #endif
  302 #ifdef NETATALK
  303         case AF_APPLETALK:
  304                 isr = NETISR_ATALK2;
  305                 break;
  306 #endif
  307         default:
  308                 printf("if_simloop: can't handle af=%d\n", af);
  309                 m_freem(m);
  310                 return (EAFNOSUPPORT);
  311         }
  312         ifp->if_ipackets++;
  313         ifp->if_ibytes += m->m_pkthdr.len;
  314         netisr_queue(isr, m);   /* mbuf is free'd on failure. */
  315         return (0);
  316 }
  317 
  318 /* ARGSUSED */
  319 static void
  320 lortrequest(cmd, rt, info)
  321         int cmd;
  322         struct rtentry *rt;
  323         struct rt_addrinfo *info;
  324 {
  325         RT_LOCK_ASSERT(rt);
  326         if (rt)
  327                 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  328 }
  329 
  330 /*
  331  * Process an ioctl request.
  332  */
  333 /* ARGSUSED */
  334 int
  335 loioctl(ifp, cmd, data)
  336         register struct ifnet *ifp;
  337         u_long cmd;
  338         caddr_t data;
  339 {
  340         register struct ifaddr *ifa;
  341         register struct ifreq *ifr = (struct ifreq *)data;
  342         register int error = 0;
  343 
  344         switch (cmd) {
  345 
  346         case SIOCSIFADDR:
  347                 ifp->if_flags |= IFF_UP | IFF_RUNNING;
  348                 ifa = (struct ifaddr *)data;
  349                 ifa->ifa_rtrequest = lortrequest;
  350                 /*
  351                  * Everything else is done at a higher level.
  352                  */
  353                 break;
  354 
  355         case SIOCADDMULTI:
  356         case SIOCDELMULTI:
  357                 if (ifr == 0) {
  358                         error = EAFNOSUPPORT;           /* XXX */
  359                         break;
  360                 }
  361                 switch (ifr->ifr_addr.sa_family) {
  362 
  363 #ifdef INET
  364                 case AF_INET:
  365                         break;
  366 #endif
  367 #ifdef INET6
  368                 case AF_INET6:
  369                         break;
  370 #endif
  371 
  372                 default:
  373                         error = EAFNOSUPPORT;
  374                         break;
  375                 }
  376                 break;
  377 
  378         case SIOCSIFMTU:
  379                 ifp->if_mtu = ifr->ifr_mtu;
  380                 break;
  381 
  382         case SIOCSIFFLAGS:
  383                 break;
  384 
  385         default:
  386                 error = EINVAL;
  387         }
  388         return (error);
  389 }

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