text: /*-
   * 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.
   * 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.
   *
   *	@(#)if_loop.c	8.2 (Berkeley) 1/9/95
   * $FreeBSD: src/sys/net/if_loop.c,v 1.107 2005/08/09 10:19:58 rwatson Exp $
   */
  
  /*
   * Loopback interface driver for protocol testing and timing.
   */
  
  #include "opt_atalk.h"
  #include "opt_inet.h"
  #include "opt_inet6.h"
  #include "opt_ipx.h"
  
  #include <sys/param.h>
  #include <sys/systm.h>
  #include <sys/kernel.h>
  #include <sys/malloc.h>
  #include <sys/mbuf.h>
  #include <sys/module.h>
  #include <machine/bus.h>
  #include <sys/rman.h>
  #include <sys/socket.h>
  #include <sys/sockio.h>
  #include <sys/sysctl.h>
  
  #include <net/if.h>
  #include <net/if_clone.h>
  #include <net/if_types.h>
  #include <net/netisr.h>
  #include <net/route.h>
  #include <net/bpf.h>
  #include <net/bpfdesc.h>
  
  #ifdef	INET
  #include <netinet/in.h>
  #include <netinet/in_var.h>
  #endif
  
  #ifdef IPX
  #include <netipx/ipx.h>
  #include <netipx/ipx_if.h>
  #endif
  
  #ifdef INET6
  #ifndef INET
  #include <netinet/in.h>
  #endif
  #include <netinet6/in6_var.h>
  #include <netinet/ip6.h>
  #endif
  
  #ifdef NETATALK
  #include <netatalk/at.h>
  #include <netatalk/at_var.h>
  #endif
  
  #ifdef TINY_LOMTU
  #define	LOMTU	(1024+512)
  #elif defined(LARGE_LOMTU)
  #define LOMTU	131072
  #else
  #define LOMTU	16384
  #endif
  
  #define LONAME	"lo"
  
  struct lo_softc {
  	struct	ifnet *sc_ifp;
  	LIST_ENTRY(lo_softc) sc_next;
  };
  
  int		loioctl(struct ifnet *, u_long, caddr_t);
  static void	lortrequest(int, struct rtentry *, struct rt_addrinfo *);
  int		looutput(struct ifnet *ifp, struct mbuf *m,
  		    struct sockaddr *dst, struct rtentry *rt);
  static int	lo_clone_create(struct if_clone *, int);
  static void	lo_clone_destroy(struct ifnet *);
  
  struct ifnet *loif = NULL;			/* Used externally */
  
  static MALLOC_DEFINE(M_LO, LONAME, "Loopback Interface");
  
  static struct mtx lo_mtx;
  static LIST_HEAD(lo_list, lo_softc) lo_list;
  
  IFC_SIMPLE_DECLARE(lo, 1);
  
  static void
  lo_clone_destroy(ifp)
  	struct ifnet *ifp;
  {
  	struct lo_softc *sc;
  	
  	sc = ifp->if_softc;
  
  	/* XXX: destroying lo0 will lead to panics. */
  	KASSERT(loif != ifp, ("%s: destroying lo0", __func__));
  
  	mtx_lock(&lo_mtx);
  	LIST_REMOVE(sc, sc_next);
  	mtx_unlock(&lo_mtx);
  	bpfdetach(ifp);
  	if_detach(ifp);
  	if_free(ifp);
  	free(sc, M_LO);
  }
  
  static int
  lo_clone_create(ifc, unit)
  	struct if_clone *ifc;
  	int unit;
  {
  	struct ifnet *ifp;
  	struct lo_softc *sc;
  
  	MALLOC(sc, struct lo_softc *, sizeof(*sc), M_LO, M_WAITOK | M_ZERO);
  	ifp = sc->sc_ifp = if_alloc(IFT_LOOP);
  	if (ifp == NULL) {
  		free(sc, M_LO);
  		return (ENOSPC);
  	}
  
  	if_initname(ifp, ifc->ifc_name, unit);
  	ifp->if_mtu = LOMTU;
  	ifp->if_flags = IFF_LOOPBACK | IFF_MULTICAST;
  	ifp->if_ioctl = loioctl;
  	ifp->if_output = looutput;
  	ifp->if_snd.ifq_maxlen = ifqmaxlen;
  	ifp->if_softc = sc;
  	if_attach(ifp);
  	bpfattach(ifp, DLT_NULL, sizeof(u_int32_t));
  	mtx_lock(&lo_mtx);
  	LIST_INSERT_HEAD(&lo_list, sc, sc_next);
  	mtx_unlock(&lo_mtx);
  	if (loif == NULL)
  		loif = ifp;
  
  	return (0);
  }
  
  static int
  loop_modevent(module_t mod, int type, void *data) 
  { 
  	switch (type) { 
  	case MOD_LOAD: 
  		mtx_init(&lo_mtx, "lo_mtx", NULL, MTX_DEF);
  		LIST_INIT(&lo_list);
  		if_clone_attach(&lo_cloner);
  		break; 
  	case MOD_UNLOAD: 
  		printf("loop module unload - not possible for this module type\n"); 
  		return EINVAL; 
  	default:
  		return EOPNOTSUPP;
  	} 
  	return 0; 
  } 
  
  static moduledata_t loop_mod = { 
  	"loop", 
  	loop_modevent, 
  	0
  }; 
  
  DECLARE_MODULE(loop, loop_mod, SI_SUB_PROTO_IFATTACHDOMAIN, SI_ORDER_ANY);
  
  int
  looutput(ifp, m, dst, rt)
  	struct ifnet *ifp;
  	register struct mbuf *m;
  	struct sockaddr *dst;
  	register struct rtentry *rt;
  {
  	u_int32_t af;
  
  	M_ASSERTPKTHDR(m); /* check if we have the packet header */
  
  	if (rt && rt->rt_flags & (RTF_REJECT|RTF_BLACKHOLE)) {
  		m_freem(m);
  		return (rt->rt_flags & RTF_BLACKHOLE ? 0 :
  		        rt->rt_flags & RTF_HOST ? EHOSTUNREACH : ENETUNREACH);
  	}
  
  	ifp->if_opackets++;
  	ifp->if_obytes += m->m_pkthdr.len;
  
  	/* BPF writes need to be handled specially. */
  	if (dst->sa_family == AF_UNSPEC) {
  		bcopy(dst->sa_data, &af, sizeof(af));
  		dst->sa_family = af;
  	}
  
  #if 1	/* XXX */
  	switch (dst->sa_family) {
  	case AF_INET:
  	case AF_INET6:
  	case AF_IPX:
  	case AF_APPLETALK:
  		break;
  	default:
  		printf("looutput: af=%d unexpected\n", dst->sa_family);
  		m_freem(m);
  		return (EAFNOSUPPORT);
  	}
  #endif
  	return(if_simloop(ifp, m, dst->sa_family, 0));
  }
  
  /*
   * if_simloop()
   *
   * This function is to support software emulation of hardware loopback,
   * i.e., for interfaces with the IFF_SIMPLEX attribute. Since they can't
   * hear their own broadcasts, we create a copy of the packet that we
   * would normally receive via a hardware loopback.
   *
   * This function expects the packet to include the media header of length hlen.
   */
  
  int
  if_simloop(ifp, m, af, hlen)
  	struct ifnet *ifp;
  	struct mbuf *m;
  	int af;
  	int hlen;
  {
  	int isr;
  
  	M_ASSERTPKTHDR(m);
  	m_tag_delete_nonpersistent(m);
  	m->m_pkthdr.rcvif = ifp;
  
  	/* Let BPF see incoming packet */
  	if (ifp->if_bpf) {
  		if (ifp->if_bpf->bif_dlt == DLT_NULL) {
  			u_int32_t af1 = af;	/* XXX beware sizeof(af) != 4 */
  			/*
  			 * We need to prepend the address family.
  			 */
  			bpf_mtap2(ifp->if_bpf, &af1, sizeof(af1), m);
  		} else
  			bpf_mtap(ifp->if_bpf, m);
  	}
  
  	/* Strip away media header */
  	if (hlen > 0) {
  		m_adj(m, hlen);
  #if defined(__alpha__) || defined(__ia64__) || defined(__sparc64__)
  		/* The alpha doesn't like unaligned data.
  		 * We move data down in the first mbuf */
  		if (mtod(m, vm_offset_t) & 3) {
  			KASSERT(hlen >= 3, ("if_simloop: hlen too small"));
  			bcopy(m->m_data, 
  			    (char *)(mtod(m, vm_offset_t) 
  				- (mtod(m, vm_offset_t) & 3)),
  			    m->m_len);
  			m->m_data -= (mtod(m,vm_offset_t) & 3);
  		}
  #endif
  	}
  
  	/* Deliver to upper layer protocol */
  	switch (af) {
  #ifdef INET
  	case AF_INET:
  		isr = NETISR_IP;
  		break;
  #endif
  #ifdef INET6
  	case AF_INET6:
  		m->m_flags |= M_LOOP;
  		isr = NETISR_IPV6;
  		break;
  #endif
  #ifdef IPX
  	case AF_IPX:
  		isr = NETISR_IPX;
  		break;
  #endif
  #ifdef NETATALK
  	case AF_APPLETALK:
  		isr = NETISR_ATALK2;
  		break;
  #endif
  	default:
  		printf("if_simloop: can't handle af=%d\n", af);
  		m_freem(m);
  		return (EAFNOSUPPORT);
  	}
  	ifp->if_ipackets++;
  	ifp->if_ibytes += m->m_pkthdr.len;
  	netisr_queue(isr, m);	/* mbuf is free'd on failure. */
  	return (0);
  }
  
  /* ARGSUSED */
  static void
  lortrequest(cmd, rt, info)
  	int cmd;
  	struct rtentry *rt;
  	struct rt_addrinfo *info;
  {
  	RT_LOCK_ASSERT(rt);
  	rt->rt_rmx.rmx_mtu = rt->rt_ifp->if_mtu;
  }
  
  /*
   * Process an ioctl request.
   */
  /* ARGSUSED */
  int
  loioctl(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;
  		ifp->if_drv_flags |= IFF_DRV_RUNNING;
  		ifa = (struct ifaddr *)data;
  		ifa->ifa_rtrequest = lortrequest;
  		/*
  		 * 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
  #ifdef INET6
  		case AF_INET6:
  			break;
  #endif
  
  		default:
  			error = EAFNOSUPPORT;
  			break;
  		}
  		break;
  
  	case SIOCSIFMTU:
  		ifp->if_mtu = ifr->ifr_mtu;
  		break;
  
  	case SIOCSIFFLAGS:
  		break;
  
  	default:
  		error = EINVAL;
  	}
  	return (error);
  }
  