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  * 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: releng/6.4/sys/net/if_loop.c 166943 2007-02-24 16:08:03Z cognet $
   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_ifp;
   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         if_free(ifp);
  133         free(sc, M_LO);
  134 }
  135 
  136 static int
  137 lo_clone_create(ifc, unit)
  138         struct if_clone *ifc;
  139         int unit;
  140 {
  141         struct ifnet *ifp;
  142         struct lo_softc *sc;
  143 
  144         MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
  145         ifp = sc->sc_ifp = if_alloc(IFT_LOOP);
  146         if (ifp == NULL) {
  147                 free(sc, M_LO);
  148                 return (ENOSPC);
  149         }
  150 
  151         if_initname(ifp, ifc->ifc_name, unit);
  152         ifp->if_mtu = LOMTU;
  153         ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  154         ifp->if_ioctl = loioctl;
  155         ifp->if_output = looutput;
  156         ifp->if_snd.ifq_maxlen = ifqmaxlen;
  157         ifp->if_softc = sc;
  158         if_attach(ifp);
  159         bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  160         mtx_lock(&lo_mtx);
  161         LIST_INSERT_HEAD(&lo_list, sc, sc_next);
  162         mtx_unlock(&lo_mtx);
  163         if (loif == NULL)
  164                 loif = ifp;
  165 
  166         return (0);
  167 }
  168 
  169 static int
  170 loop_modevent(module_t mod, int type, void *data) 
  171 { 
  172         switch (type) { 
  173         case MOD_LOAD: 
  174                 mtx_init(&lo_mtx, "lo_mtx", NULL, MTX_DEF);
  175                 LIST_INIT(&lo_list);
  176                 if_clone_attach(&lo_cloner);
  177                 break; 
  178         case MOD_UNLOAD: 
  179                 printf("loop module unload - not possible for this module type\n"); 
  180                 return EINVAL; 
  181         default:
  182                 return EOPNOTSUPP;
  183         } 
  184         return 0; 
  185 } 
  186 
  187 static moduledata_t loop_mod = { 
  188         "loop", 
  189         loop_modevent, 
  190         0
  191 }; 
  192 
  193 DECLARE_MODULE(loop, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  194 
  195 int
  196 looutput(ifp, m, dst, rt)
  197         struct ifnet *ifp;
  198         register struct mbuf *m;
  199         struct sockaddr *dst;
  200         register struct rtentry *rt;
  201 {
  202         u_int32_t af;
  203 
  204         M_ASSERTPKTHDR(m); /* check if we have the packet header */
  205 
  206         if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  207                 m_freem(m);
  208                 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  209                         rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  210         }
  211 
  212         ifp->if_opackets++;
  213         ifp->if_obytes += m->m_pkthdr.len;
  214 
  215         /* BPF writes need to be handled specially. */
  216         if (dst->sa_family == AF_UNSPEC) {
  217                 bcopy(dst->sa_data, &af, sizeof(af));
  218                 dst->sa_family = af;
  219         }
  220 
  221 #if 1   /* XXX */
  222         switch (dst->sa_family) {
  223         case AF_INET:
  224         case AF_INET6:
  225         case AF_IPX:
  226         case AF_APPLETALK:
  227                 break;
  228         default:
  229                 printf("looutput: af=%d unexpected\n", dst->sa_family);
  230                 m_freem(m);
  231                 return (EAFNOSUPPORT);
  232         }
  233 #endif
  234         return(if_simloop(ifp, m, dst->sa_family, 0));
  235 }
  236 
  237 /*
  238  * if_simloop()
  239  *
  240  * This function is to support software emulation of hardware loopback,
  241  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
  242  * hear their own broadcasts, we create a copy of the packet that we
  243  * would normally receive via a hardware loopback.
  244  *
  245  * This function expects the packet to include the media header of length hlen.
  246  */
  247 
  248 int
  249 if_simloop(ifp, m, af, hlen)
  250         struct ifnet *ifp;
  251         struct mbuf *m;
  252         int af;
  253         int hlen;
  254 {
  255         int isr;
  256 
  257         M_ASSERTPKTHDR(m);
  258         m_tag_delete_nonpersistent(m);
  259         m->m_pkthdr.rcvif = ifp;
  260 
  261         /*
  262          * Let BPF see incoming packet in the following manner:
  263          *  - Emulated packet loopback for a simplex interface 
  264          *    (net/if_ethersubr.c)
  265          *      -> passes it to ifp's BPF
  266          *  - IPv4/v6 multicast packet loopback (netinet(6)/ip(6)_output.c)
  267          *      -> not passes it to any BPF
  268          *  - Normal packet loopback from myself to myself (net/if_loop.c)
  269          *      -> passes to lo0's BPF (even in case of IPv6, where ifp!=lo0)
  270          */
  271         if (hlen > 0) {
  272                 if (bpf_peers_present(ifp->if_bpf)) {
  273                         bpf_mtap(ifp->if_bpf, m);
  274                 }
  275         } else {
  276                 if (bpf_peers_present(loif->if_bpf)) {
  277                         if ((m->m_flags & M_MCAST) == 0 || loif == ifp) {
  278                                 /* XXX beware sizeof(af) != 4 */
  279                                 u_int32_t af1 = af;     
  280 
  281                                 /*
  282                                  * We need to prepend the address family.
  283                                  */
  284                                 bpf_mtap2(loif->if_bpf, &af1, sizeof(af1), m);
  285                         }
  286                 }
  287         }
  288 
  289         /* Strip away media header */
  290         if (hlen > 0) {
  291                 m_adj(m, hlen);
  292 #ifndef __NO_STRICT_ALIGNMENT
  293                 /* The alpha doesn't like unaligned data.
  294                  * We move data down in the first mbuf */
  295                 if (mtod(m, vm_offset_t) & 3) {
  296                         KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  297                         bcopy(m->m_data, 
  298                             (char *)(mtod(m, vm_offset_t) 
  299                                 - (mtod(m, vm_offset_t) & 3)),
  300                             m->m_len);
  301                         m->m_data -= (mtod(m,vm_offset_t) & 3);
  302                 }
  303 #endif
  304         }
  305 
  306         /* Deliver to upper layer protocol */
  307         switch (af) {
  308 #ifdef INET
  309         case AF_INET:
  310                 isr = NETISR_IP;
  311                 break;
  312 #endif
  313 #ifdef INET6
  314         case AF_INET6:
  315                 m->m_flags |= M_LOOP;
  316                 isr = NETISR_IPV6;
  317                 break;
  318 #endif
  319 #ifdef IPX
  320         case AF_IPX:
  321                 isr = NETISR_IPX;
  322                 break;
  323 #endif
  324 #ifdef NETATALK
  325         case AF_APPLETALK:
  326                 isr = NETISR_ATALK2;
  327                 break;
  328 #endif
  329         default:
  330                 printf("if_simloop: can't handle af=%d\n", af);
  331                 m_freem(m);
  332                 return (EAFNOSUPPORT);
  333         }
  334         ifp->if_ipackets++;
  335         ifp->if_ibytes += m->m_pkthdr.len;
  336         netisr_queue(isr, m);   /* mbuf is free'd on failure. */
  337         return (0);
  338 }
  339 
  340 /* ARGSUSED */
  341 static void
  342 lortrequest(cmd, rt, info)
  343         int cmd;
  344         struct rtentry *rt;
  345         struct rt_addrinfo *info;
  346 {
  347         RT_LOCK_ASSERT(rt);
  348         rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  349 }
  350 
  351 /*
  352  * Process an ioctl request.
  353  */
  354 /* ARGSUSED */
  355 int
  356 loioctl(ifp, cmd, data)
  357         register struct ifnet *ifp;
  358         u_long cmd;
  359         caddr_t data;
  360 {
  361         register struct ifaddr *ifa;
  362         register struct ifreq *ifr = (struct ifreq *)data;
  363         register int error = 0;
  364 
  365         switch (cmd) {
  366 
  367         case SIOCSIFADDR:
  368                 ifp->if_flags |= IFF_UP;
  369                 ifp->if_drv_flags |= IFF_DRV_RUNNING;
  370                 ifa = (struct ifaddr *)data;
  371                 ifa->ifa_rtrequest = lortrequest;
  372                 /*
  373                  * Everything else is done at a higher level.
  374                  */
  375                 break;
  376 
  377         case SIOCADDMULTI:
  378         case SIOCDELMULTI:
  379                 if (ifr == 0) {
  380                         error = EAFNOSUPPORT;           /* XXX */
  381                         break;
  382                 }
  383                 switch (ifr->ifr_addr.sa_family) {
  384 
  385 #ifdef INET
  386                 case AF_INET:
  387                         break;
  388 #endif
  389 #ifdef INET6
  390                 case AF_INET6:
  391                         break;
  392 #endif
  393 
  394                 default:
  395                         error = EAFNOSUPPORT;
  396                         break;
  397                 }
  398                 break;
  399 
  400         case SIOCSIFMTU:
  401                 ifp->if_mtu = ifr->ifr_mtu;
  402                 break;
  403 
  404         case SIOCSIFFLAGS:
  405                 break;
  406 
  407         default:
  408                 error = EINVAL;
  409         }
  410         return (error);
  411 }

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