xref: /freebsd/usr.sbin/ppp/arp.c (revision 99c02d39bc884ca9fc4940c9790934602ce19355)

/*
 * sys-bsd.c - System-dependent procedures for setting up
 * PPP interfaces on bsd-4.4-ish systems (including 386BSD, NetBSD, etc.)
 *
 * Copyright (c) 1989 Carnegie Mellon University.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by Carnegie Mellon University.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 *
 * $Id: arp.c,v 1.6 1997/01/03 20:19:42 wollman Exp $
 *
 */

/*
 * TODO:
 */

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/uio.h>
#include <sys/socket.h>
#include <sys/time.h>
#include <sys/errno.h>
#include <unistd.h>
#include <string.h>

#include <net/if.h>
#include <net/if_var.h>
#include <net/route.h>
#include <net/if_dl.h>
#include <netinet/in.h>
#include <stdio.h>
#include <fcntl.h>
#ifdef __bsdi__
#include <kvm.h>
#endif
#include <net/if_types.h>
#include <netinet/in_var.h>
#include <netinet/if_ether.h>
#include "log.h"

#if RTM_VERSION >= 3
#include <netinet/if_ether.h>
#endif

static int rtm_seq;

static int get_ether_addr __P((int, u_long, struct sockaddr_dl *));

#define BCOPY(s, d, l)		memcpy(d, s, l)
#define BZERO(s, n)		memset(s, 0, n)
/*
 * SET_SA_FAMILY - set the sa_family field of a struct sockaddr,
 * if it exists.
 */
#define SET_SA_FAMILY(addr, family)		\
    BZERO((char *) &(addr), sizeof(addr));	\
    addr.sa_family = (family); 			\
    addr.sa_len = sizeof(addr);


#if RTM_VERSION >= 3

/*
 * sifproxyarp - Make a proxy ARP entry for the peer.
 */
static struct {
    struct rt_msghdr		hdr;
    struct sockaddr_inarp	dst;
    struct sockaddr_dl		hwa;
    char			extra[128];
} arpmsg;

static int arpmsg_valid;

int
sifproxyarp(unit, hisaddr)
    int unit;
    u_long hisaddr;
{
    int routes;

    /*
     * Get the hardware address of an interface on the same subnet
     * as our local address.
     */
    memset(&arpmsg, 0, sizeof(arpmsg));
    if (!get_ether_addr(unit, hisaddr, &arpmsg.hwa)) {
	logprintf("Cannot determine ethernet address for proxy ARP\n");
	return 0;
    }

    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
	logprintf("sifproxyarp: opening routing socket: \n");
	return 0;
    }

    arpmsg.hdr.rtm_type = RTM_ADD;
    arpmsg.hdr.rtm_flags = RTF_ANNOUNCE | RTF_HOST | RTF_STATIC;
    arpmsg.hdr.rtm_version = RTM_VERSION;
    arpmsg.hdr.rtm_seq = ++rtm_seq;
    arpmsg.hdr.rtm_addrs = RTA_DST | RTA_GATEWAY;
    arpmsg.hdr.rtm_inits = RTV_EXPIRE;
    arpmsg.dst.sin_len = sizeof(struct sockaddr_inarp);
    arpmsg.dst.sin_family = AF_INET;
    arpmsg.dst.sin_addr.s_addr = hisaddr;
    arpmsg.dst.sin_other = SIN_PROXY;

    arpmsg.hdr.rtm_msglen = (char *) &arpmsg.hwa - (char *) &arpmsg
	+ arpmsg.hwa.sdl_len;
    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
	logprintf("add proxy arp entry: \n");
	close(routes);
	return 0;
    }

    close(routes);
    arpmsg_valid = 1;
    return 1;
}

/*
 * cifproxyarp - Delete the proxy ARP entry for the peer.
 */
int
cifproxyarp(unit, hisaddr)
    int unit;
    u_long hisaddr;
{
    int routes;

    if (!arpmsg_valid)
	return 0;
    arpmsg_valid = 0;

    arpmsg.hdr.rtm_type = RTM_DELETE;
    arpmsg.hdr.rtm_seq = ++rtm_seq;

    if ((routes = socket(PF_ROUTE, SOCK_RAW, AF_INET)) < 0) {
	logprintf("sifproxyarp: opening routing socket: \n");
	return 0;
    }

    if (write(routes, &arpmsg, arpmsg.hdr.rtm_msglen) < 0) {
	logprintf("delete proxy arp entry: \n");
	close(routes);
	return 0;
    }

    close(routes);
    return 1;
}

#else	/* RTM_VERSION */

/*
 * sifproxyarp - Make a proxy ARP entry for the peer.
 */
int
sifproxyarp(unit, hisaddr)
    int unit;
    u_long hisaddr;
{
    struct arpreq arpreq;
    struct {
	struct sockaddr_dl	sdl;
	char			space[128];
    } dls;

    BZERO(&arpreq, sizeof(arpreq));

    /*
     * Get the hardware address of an interface on the same subnet
     * as our local address.
     */
    if (!get_ether_addr(unit, hisaddr, &dls.sdl)) {
	LogPrintf(LOG_PHASE_BIT, "Cannot determine ethernet address for proxy ARP\n");
	return 0;
    }

    arpreq.arp_ha.sa_len = sizeof(struct sockaddr);
    arpreq.arp_ha.sa_family = AF_UNSPEC;
    BCOPY(LLADDR(&dls.sdl), arpreq.arp_ha.sa_data, dls.sdl.sdl_alen);
    SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
    ((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = hisaddr;
    arpreq.arp_flags = ATF_PERM | ATF_PUBL;
    if (ioctl(unit, SIOCSARP, (caddr_t)&arpreq) < 0) {
	fprintf(stderr, "ioctl(SIOCSARP): \n");
	return 0;
    }

    return 1;
}

/*
 * cifproxyarp - Delete the proxy ARP entry for the peer.
 */
int
cifproxyarp(unit, hisaddr)
    int unit;
    u_long hisaddr;
{
    struct arpreq arpreq;

    BZERO(&arpreq, sizeof(arpreq));
    SET_SA_FAMILY(arpreq.arp_pa, AF_INET);
    ((struct sockaddr_in *) &arpreq.arp_pa)->sin_addr.s_addr = hisaddr;
    if (ioctl(unit, SIOCDARP, (caddr_t)&arpreq) < 0) {
	fprintf(stderr, "ioctl(SIOCDARP): \n");
	return 0;
    }
    return 1;
}
#endif	/* RTM_VERSION */


/*
 * get_ether_addr - get the hardware address of an interface on the
 * the same subnet as ipaddr.
 */
#define MAX_IFS		32

int
get_ether_addr(s, ipaddr, hwaddr)
    int    s;
    u_long ipaddr;
    struct sockaddr_dl *hwaddr;
{
    struct ifreq *ifr, *ifend, *ifp;
    u_long ina, mask;
    struct sockaddr_dl *dla;
    struct ifreq ifreq;
    struct ifconf ifc;
    struct ifreq ifs[MAX_IFS];

    ifc.ifc_len = sizeof(ifs);
    ifc.ifc_req = ifs;
    if (ioctl(s, SIOCGIFCONF, &ifc) < 0) {
	fprintf(stderr, "ioctl(SIOCGIFCONF): \n");
	return 0;
    }

    /*
     * Scan through looking for an interface with an Internet
     * address on the same subnet as `ipaddr'.
     */
    ifend = (struct ifreq *) (ifc.ifc_buf + ifc.ifc_len);
    for (ifr = ifc.ifc_req; ifr < ifend; ) {
	if (ifr->ifr_addr.sa_family == AF_INET) {
	    ina = ((struct sockaddr_in *) &ifr->ifr_addr)->sin_addr.s_addr;
	    strncpy(ifreq.ifr_name, ifr->ifr_name, sizeof(ifreq.ifr_name));
	    ifreq.ifr_name[sizeof(ifreq.ifr_name)-1]='\0';
	    /*
	     * Check that the interface is up, and not point-to-point
	     * or loopback.
	     */
	    if (ioctl(s, SIOCGIFFLAGS, &ifreq) < 0)
		continue;
	    if ((ifreq.ifr_flags &
		 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|IFF_LOOPBACK|IFF_NOARP))
		 != (IFF_UP|IFF_BROADCAST))
		goto nextif;
	    /*
	     * Get its netmask and check that it's on the right subnet.
	     */
	    if (ioctl(s, SIOCGIFNETMASK, &ifreq) < 0)
		continue;
	    mask = ((struct sockaddr_in *) &ifreq.ifr_addr)->sin_addr.s_addr;
	    if ((ipaddr & mask) != (ina & mask))
		goto nextif;

	    break;
	}
nextif:
	ifr = (struct ifreq *) ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len);
    }

    if (ifr >= ifend)
	return 0;
    LogPrintf(LOG_PHASE_BIT, "found interface %s for proxy arp\n", ifr->ifr_name);

    /*
     * Now scan through again looking for a link-level address
     * for this interface.
     */
    ifp = ifr;
    for (ifr = ifc.ifc_req; ifr < ifend; ) {
	if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0
	    && ifr->ifr_addr.sa_family == AF_LINK) {
	    /*
	     * Found the link-level address - copy it out
	     */
	    dla = (struct sockaddr_dl *) &ifr->ifr_addr;
#ifdef __bsdi__
	    if (dla->sdl_alen == 0)
	      kmemgetether(ifr->ifr_name, dla);
#endif
	    BCOPY(dla, hwaddr, dla->sdl_len);
	    return 1;
	}
	ifr = (struct ifreq *) ((char *)&ifr->ifr_addr + ifr->ifr_addr.sa_len);
    }

    return 0;
}

#ifdef __bsdi__
#include <nlist.h>

struct nlist nl[] = {
#define N_IFNET		0
	{ "_ifnet" },
	"",
};


kvm_t *kvmd;

/*
 * Read kernel memory, return 0 on success.
 */
int
kread(addr, buf, size)
  u_long addr;
  char *buf;
  int size;
{

	if (kvm_read(kvmd, addr, buf, size) != size) {
		/* XXX this duplicates kvm_read's error printout */
		(void)fprintf(stderr, "kvm_read %s\n",
			kvm_geterr(kvmd));
		return (-1);
	}
	return (0);
}

kmemgetether(ifname, dlo)
char *ifname;
struct sockaddr_dl *dlo;
{
  struct ifnet ifnet;
  int n;
  u_long addr, ifaddraddr, ifnetfound, ifaddrfound;
  char name[16+32];
  struct sockaddr *sa;
  char *cp;
  struct sockaddr_dl *sdl;
  union {
	  struct ifaddr ifa;
	  struct in_ifaddr in;
  } ifaddr;
  struct arpcom ac;

  kvmd = kvm_open(NULL, NULL, NULL, O_RDONLY, NULL);
  if (kvmd) {
    n = kvm_nlist(kvmd, nl);
    if (n >= 0) {
      addr = nl[N_IFNET].n_value;
      kread(addr, (char *)&addr, sizeof(addr));
      ifaddraddr = ifnetfound = 0;
      while (addr || ifaddraddr) {
	ifnetfound = addr;
	if (ifaddraddr == 0) {
	  if (kread(addr, (char *)&ifnet, sizeof(ifnet)) ||
	      kread((u_long)ifnet.if_name, name, 16))
		return;
	  name[15] = 0;
	  addr = (u_long) ifnet.if_next;
	  cp = (char *)index(name, '\0');
	  cp += sprintf(cp, "%d", ifnet.if_unit);
	  *cp = '\0';
	  ifaddraddr = (u_long)ifnet.if_addrlist;
	}
	ifaddrfound = ifaddraddr;
	if (ifaddraddr) {
	  if (kread(ifaddraddr, (char *)&ifaddr, sizeof ifaddr)) {
	    ifaddraddr = 0;
	    continue;
	  }
#define CP(x) ((char *)(x))
	  cp = (CP(ifaddr.ifa.ifa_addr) - CP(ifaddraddr)) + CP(&ifaddr);
	  sa = (struct sockaddr *)cp;
	  if (sa->sa_family == AF_LINK && strcmp(ifname, name) == 0) {
	    sdl = (struct sockaddr_dl *)sa;
	    cp = (char *)LLADDR(sdl);
	    n = sdl->sdl_alen;
	    if (ifnet.if_type == IFT_ETHER) {
		if (n == 0) {
		  kread(ifnetfound, (char *)&ac, sizeof(ac));
	    	  cp = (char *)LLADDR(sdl);
		  bcopy((char *)ac.ac_enaddr, cp, 6);
		  sdl->sdl_alen = 6;
		}
		bcopy(sdl, dlo, sizeof(*sdl));
		return;
	    }
	  }
	  ifaddraddr = (u_long)ifaddr.ifa.ifa_next;
	}
      }
    }
  }
}
#endif

#ifdef DEBUG
main()
{
    u_long ipaddr;
    int s;

    s = socket(AF_INET, SOCK_DGRAM, 0);
    ipaddr = inet_addr("192.168.1.32");
    sifproxyarp(s, ipaddr);
    close(s);
}
#endif