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/5.0/sys/net/if_loop.c 108056 2002-12-18 21:03:41Z rwatson $
   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 NS
   86 #include <netns/ns.h>
   87 #include <netns/ns_if.h>
   88 #endif
   89 
   90 #ifdef NETATALK
   91 #include <netatalk/at.h>
   92 #include <netatalk/at_var.h>
   93 #endif
   94 
   95 #ifdef TINY_LOMTU
   96 #define LOMTU   (1024+512)
   97 #elif defined(LARGE_LOMTU)
   98 #define LOMTU   131072
   99 #else
  100 #define LOMTU   16384
  101 #endif
  102 
  103 #define LONAME  "lo"
  104 
  105 struct lo_softc {
  106         struct  ifnet sc_if;            /* network-visible interface */
  107         LIST_ENTRY(lo_softc) sc_next;
  108 };
  109 
  110 int             loioctl(struct ifnet *, u_long, caddr_t);
  111 static void     lortrequest(int, struct rtentry *, struct rt_addrinfo *);
  112 int             looutput(struct ifnet *ifp, struct mbuf *m,
  113                     struct sockaddr *dst, struct rtentry *rt);
  114 int             lo_clone_create(struct if_clone *, int);
  115 void            lo_clone_destroy(struct ifnet *);
  116 
  117 struct ifnet *loif = NULL;                      /* Used externally */
  118 
  119 static MALLOC_DEFINE(M_LO, LONAME, "Loopback Interface");
  120 
  121 static LIST_HEAD(lo_list, lo_softc) lo_list;
  122 
  123 struct if_clone lo_cloner = IF_CLONE_INITIALIZER(LONAME,
  124     lo_clone_create, lo_clone_destroy, 1, IF_MAXUNIT);
  125 
  126 void
  127 lo_clone_destroy(ifp)
  128         struct ifnet *ifp;
  129 {
  130         struct lo_softc *sc;
  131         
  132         sc = ifp->if_softc;
  133 
  134         /* XXX: destroying lo0 will lead to panics. */
  135         KASSERT(loif != ifp, ("%s: destroying lo0", __func__));
  136 
  137         bpfdetach(ifp);
  138         if_detach(ifp);
  139         LIST_REMOVE(sc, sc_next);
  140         free(sc, M_LO);
  141 }
  142 
  143 int
  144 lo_clone_create(ifc, unit)
  145         struct if_clone *ifc;
  146         int unit;
  147 {
  148         struct lo_softc *sc;
  149 
  150         MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
  151 
  152         sc->sc_if.if_name = LONAME;
  153         sc->sc_if.if_unit = unit;
  154         sc->sc_if.if_mtu = LOMTU;
  155         sc->sc_if.if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  156         sc->sc_if.if_ioctl = loioctl;
  157         sc->sc_if.if_output = looutput;
  158         sc->sc_if.if_type = IFT_LOOP;
  159         sc->sc_if.if_snd.ifq_maxlen = ifqmaxlen;
  160         sc->sc_if.if_softc = sc;
  161         if_attach(&sc->sc_if);
  162         bpfattach(&sc->sc_if, DLT_NULL, sizeof(u_int));
  163         LIST_INSERT_HEAD(&lo_list, sc, sc_next);
  164         if (loif == NULL)
  165                 loif = &sc->sc_if;
  166 
  167         return (0);
  168 }
  169 
  170 static int
  171 loop_modevent(module_t mod, int type, void *data) 
  172 { 
  173         switch (type) { 
  174         case MOD_LOAD: 
  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         } 
  182         return 0; 
  183 } 
  184 
  185 static moduledata_t loop_mod = { 
  186         "loop", 
  187         loop_modevent, 
  188         0
  189 }; 
  190 
  191 DECLARE_MODULE(loop, loop_mod, SI_SUB_PSEUDO, SI_ORDER_ANY);
  192 
  193 int
  194 looutput(ifp, m, dst, rt)
  195         struct ifnet *ifp;
  196         register struct mbuf *m;
  197         struct sockaddr *dst;
  198         register struct rtentry *rt;
  199 {
  200         if ((m->m_flags & M_PKTHDR) == 0)
  201                 panic("looutput no HDR");
  202 
  203         if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  204                 m_freem(m);
  205                 return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  206                         rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  207         }
  208         /*
  209          * KAME requires that the packet to be contiguous on the
  210          * mbuf.  We need to make that sure.
  211          * this kind of code should be avoided.
  212          * XXX: fails to join if interface MTU > MCLBYTES.  jumbogram?
  213          */
  214         if (m && m->m_next != NULL && m->m_pkthdr.len < MCLBYTES) {
  215                 struct mbuf *n;
  216 
  217                 MGETHDR(n, M_DONTWAIT, MT_HEADER);
  218                 if (!n)
  219                         goto contiguousfail;
  220                 MCLGET(n, M_DONTWAIT);
  221                 if (! (n->m_flags & M_EXT)) {
  222                         m_freem(n);
  223                         goto contiguousfail;
  224                 }
  225 
  226                 m_copydata(m, 0, m->m_pkthdr.len, mtod(n, caddr_t));
  227                 n->m_pkthdr = m->m_pkthdr;
  228                 n->m_len = m->m_pkthdr.len;
  229                 SLIST_INIT(&m->m_pkthdr.tags);
  230 #ifdef MAC
  231                 /* 
  232                  * XXXMAC: Once we put labels in tags and proper
  233                  * primitives are used for relocating mbuf header
  234                  * data, this will no longer be required.
  235                  */
  236                 m->m_pkthdr.label.l_flags &= ~MAC_FLAG_INITIALIZED;
  237 #endif
  238                 m_freem(m);
  239                 m = n;
  240         }
  241         if (0) {
  242 contiguousfail:
  243                 printf("looutput: mbuf allocation failed\n");
  244         }
  245 
  246         ifp->if_opackets++;
  247         ifp->if_obytes += m->m_pkthdr.len;
  248 #if 1   /* XXX */
  249         switch (dst->sa_family) {
  250         case AF_INET:
  251         case AF_INET6:
  252         case AF_IPX:
  253         case AF_NS:
  254         case AF_APPLETALK:
  255                 break;
  256         default:
  257                 printf("looutput: af=%d unexpected\n", dst->sa_family);
  258                 m_freem(m);
  259                 return (EAFNOSUPPORT);
  260         }
  261 #endif
  262         return(if_simloop(ifp, m, dst->sa_family, 0));
  263 }
  264 
  265 /*
  266  * if_simloop()
  267  *
  268  * This function is to support software emulation of hardware loopback,
  269  * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
  270  * hear their own broadcasts, we create a copy of the packet that we
  271  * would normally receive via a hardware loopback.
  272  *
  273  * This function expects the packet to include the media header of length hlen.
  274  */
  275 
  276 int
  277 if_simloop(ifp, m, af, hlen)
  278         struct ifnet *ifp;
  279         struct mbuf *m;
  280         int af;
  281         int hlen;
  282 {
  283         int isr;
  284         struct ifqueue *inq = 0;
  285 
  286         KASSERT((m->m_flags & M_PKTHDR) != 0, ("if_simloop: no HDR"));
  287         m->m_pkthdr.rcvif = ifp;
  288 
  289         /* BPF write needs to be handled specially */
  290         if (af == AF_UNSPEC) {
  291                 KASSERT(m->m_len >= sizeof(int), ("if_simloop: m_len"));
  292                 af = *(mtod(m, int *));
  293                 m->m_len -= sizeof(int);
  294                 m->m_pkthdr.len -= sizeof(int);
  295                 m->m_data += sizeof(int);
  296         }
  297 
  298         /* Let BPF see incoming packet */
  299         if (ifp->if_bpf) {
  300                 struct mbuf m0, *n = m;
  301 
  302                 if (ifp->if_bpf->bif_dlt == DLT_NULL) {
  303                         /*
  304                          * We need to prepend the address family as
  305                          * a four byte field.  Cons up a dummy header
  306                          * to pacify bpf.  This is safe because bpf
  307                          * will only read from the mbuf (i.e., it won't
  308                          * try to free it or keep a pointer a to it).
  309                          */
  310                         m0.m_next = m;
  311                         m0.m_len = 4;
  312                         m0.m_data = (char *)&af;
  313                         n = &m0;
  314                 }
  315                 BPF_MTAP(ifp, n);
  316         }
  317 
  318         /* Strip away media header */
  319         if (hlen > 0) {
  320                 m_adj(m, hlen);
  321 #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
  322                 /* The alpha doesn't like unaligned data.
  323                  * We move data down in the first mbuf */
  324                 if (mtod(m, vm_offset_t) & 3) {
  325                         KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  326                         bcopy(m->m_data, 
  327                             (char *)(mtod(m, vm_offset_t) 
  328                                 - (mtod(m, vm_offset_t) & 3)),
  329                             m->m_len);
  330                         mtod(m,vm_offset_t) -= (mtod(m, vm_offset_t) & 3);
  331                 }
  332 #endif
  333         }
  334 
  335         /* Deliver to upper layer protocol */
  336         switch (af) {
  337 #ifdef INET
  338         case AF_INET:
  339                 inq = &ipintrq;
  340                 isr = NETISR_IP;
  341                 break;
  342 #endif
  343 #ifdef INET6
  344         case AF_INET6:
  345                 m->m_flags |= M_LOOP;
  346                 inq = &ip6intrq;
  347                 isr = NETISR_IPV6;
  348                 break;
  349 #endif
  350 #ifdef IPX
  351         case AF_IPX:
  352                 inq = &ipxintrq;
  353                 isr = NETISR_IPX;
  354                 break;
  355 #endif
  356 #ifdef NS
  357         case AF_NS:
  358                 inq = &nsintrq;
  359                 isr = NETISR_NS;
  360                 break;
  361 #endif
  362 #ifdef NETATALK
  363         case AF_APPLETALK:
  364                 inq = &atintrq2;
  365                 isr = NETISR_ATALK;
  366                 break;
  367 #endif
  368         default:
  369                 printf("if_simloop: can't handle af=%d\n", af);
  370                 m_freem(m);
  371                 return (EAFNOSUPPORT);
  372         }
  373         ifp->if_ipackets++;
  374         ifp->if_ibytes += m->m_pkthdr.len;
  375         (void) IF_HANDOFF(inq, m, NULL);
  376         schednetisr(isr);
  377         return (0);
  378 }
  379 
  380 /* ARGSUSED */
  381 static void
  382 lortrequest(cmd, rt, info)
  383         int cmd;
  384         struct rtentry *rt;
  385         struct rt_addrinfo *info;
  386 {
  387         if (rt) {
  388                 rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu; /* for ISO */
  389                 /*
  390                  * For optimal performance, the send and receive buffers
  391                  * should be at least twice the MTU plus a little more for
  392                  * overhead.
  393                  */
  394                 rt->rt_rmx.rmx_recvpipe =
  395                         rt->rt_rmx.rmx_sendpipe = 3 * LOMTU;
  396         }
  397 }
  398 
  399 /*
  400  * Process an ioctl request.
  401  */
  402 /* ARGSUSED */
  403 int
  404 loioctl(ifp, cmd, data)
  405         register struct ifnet *ifp;
  406         u_long cmd;
  407         caddr_t data;
  408 {
  409         register struct ifaddr *ifa;
  410         register struct ifreq *ifr = (struct ifreq *)data;
  411         register int error = 0;
  412 
  413         switch (cmd) {
  414 
  415         case SIOCSIFADDR:
  416                 ifp->if_flags |= IFF_UP | IFF_RUNNING;
  417                 ifa = (struct ifaddr *)data;
  418                 ifa->ifa_rtrequest = lortrequest;
  419                 /*
  420                  * Everything else is done at a higher level.
  421                  */
  422                 break;
  423 
  424         case SIOCADDMULTI:
  425         case SIOCDELMULTI:
  426                 if (ifr == 0) {
  427                         error = EAFNOSUPPORT;           /* XXX */
  428                         break;
  429                 }
  430                 switch (ifr->ifr_addr.sa_family) {
  431 
  432 #ifdef INET
  433                 case AF_INET:
  434                         break;
  435 #endif
  436 #ifdef INET6
  437                 case AF_INET6:
  438                         break;
  439 #endif
  440 
  441                 default:
  442                         error = EAFNOSUPPORT;
  443                         break;
  444                 }
  445                 break;
  446 
  447         case SIOCSIFMTU:
  448                 ifp->if_mtu = ifr->ifr_mtu;
  449                 break;
  450 
  451         case SIOCSIFFLAGS:
  452                 break;
  453 
  454         default:
  455                 error = EINVAL;
  456         }
  457         return (error);
  458 }

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