| Current Path : /usr/src/usr.sbin/arp/ |
FreeBSD hs32.drive.ne.jp 9.1-RELEASE FreeBSD 9.1-RELEASE #1: Wed Jan 14 12:18:08 JST 2015 root@hs32.drive.ne.jp:/sys/amd64/compile/hs32 amd64 |
| Current File : //usr/src/usr.sbin/arp/arp.c |
/*
* Copyright (c) 1984, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Sun Microsystems, Inc.
*
* 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 0
#ifndef lint
static char const copyright[] =
"@(#) Copyright (c) 1984, 1993\n\
The Regents of the University of California. All rights reserved.\n";
#endif /* not lint */
#ifndef lint
static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
#endif /* not lint */
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD: release/9.1.0/usr.sbin/arp/arp.c 237774 2012-06-29 12:05:19Z glebius $");
/*
* arp - display, set, and delete arp table entries
*/
#include <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/sockio.h>
#include <sys/sysctl.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>
#include <net/iso88025.h>
#include <netinet/in.h>
#include <netinet/if_ether.h>
#include <arpa/inet.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <netdb.h>
#include <nlist.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <strings.h>
#include <unistd.h>
typedef void (action_fn)(struct sockaddr_dl *sdl,
struct sockaddr_inarp *s_in, struct rt_msghdr *rtm);
static int search(u_long addr, action_fn *action);
static action_fn print_entry;
static action_fn nuke_entry;
static int delete(char *host, int do_proxy);
static void usage(void);
static int set(int argc, char **argv);
static int get(char *host);
static int file(char *name);
static struct rt_msghdr *rtmsg(int cmd,
struct sockaddr_inarp *dst, struct sockaddr_dl *sdl);
static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
static struct sockaddr_inarp *getaddr(char *host);
static int valid_type(int type);
static int nflag; /* no reverse dns lookups */
static char *rifname;
static time_t expire_time;
static int flags, doing_proxy, proxy_only;
/* which function we're supposed to do */
#define F_GET 1
#define F_SET 2
#define F_FILESET 3
#define F_REPLACE 4
#define F_DELETE 5
#define SETFUNC(f) { if (func) usage(); func = (f); }
int
main(int argc, char *argv[])
{
int ch, func = 0;
int rtn = 0;
int aflag = 0; /* do it for all entries */
while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
switch(ch) {
case 'a':
aflag = 1;
break;
case 'd':
SETFUNC(F_DELETE);
break;
case 'n':
nflag = 1;
break;
case 'S':
SETFUNC(F_REPLACE);
break;
case 's':
SETFUNC(F_SET);
break;
case 'f' :
SETFUNC(F_FILESET);
break;
case 'i':
rifname = optarg;
break;
case '?':
default:
usage();
}
argc -= optind;
argv += optind;
if (!func)
func = F_GET;
if (rifname) {
if (func != F_GET && !(func == F_DELETE && aflag))
errx(1, "-i not applicable to this operation");
if (if_nametoindex(rifname) == 0) {
if (errno == ENXIO)
errx(1, "interface %s does not exist", rifname);
else
err(1, "if_nametoindex(%s)", rifname);
}
}
switch (func) {
case F_GET:
if (aflag) {
if (argc != 0)
usage();
search(0, print_entry);
} else {
if (argc != 1)
usage();
rtn = get(argv[0]);
}
break;
case F_SET:
case F_REPLACE:
if (argc < 2 || argc > 6)
usage();
if (func == F_REPLACE)
(void)delete(argv[0], 0);
rtn = set(argc, argv) ? 1 : 0;
break;
case F_DELETE:
if (aflag) {
if (argc != 0)
usage();
search(0, nuke_entry);
} else {
if (argc == 2 && strncmp(argv[1], "pub", 3) == 0)
ch = SIN_PROXY;
else if (argc == 1)
ch = 0;
else
usage();
rtn = delete(argv[0], ch);
}
break;
case F_FILESET:
if (argc != 1)
usage();
rtn = file(argv[0]);
break;
}
return (rtn);
}
/*
* Process a file to set standard arp entries
*/
static int
file(char *name)
{
FILE *fp;
int i, retval;
char line[100], arg[5][50], *args[5], *p;
if ((fp = fopen(name, "r")) == NULL)
err(1, "cannot open %s", name);
args[0] = &arg[0][0];
args[1] = &arg[1][0];
args[2] = &arg[2][0];
args[3] = &arg[3][0];
args[4] = &arg[4][0];
retval = 0;
while(fgets(line, sizeof(line), fp) != NULL) {
if ((p = strchr(line, '#')) != NULL)
*p = '\0';
for (p = line; isblank(*p); p++);
if (*p == '\n' || *p == '\0')
continue;
i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
arg[2], arg[3], arg[4]);
if (i < 2) {
warnx("bad line: %s", line);
retval = 1;
continue;
}
if (set(i, args))
retval = 1;
}
fclose(fp);
return (retval);
}
/*
* Given a hostname, fills up a (static) struct sockaddr_inarp with
* the address of the host and returns a pointer to the
* structure.
*/
static struct sockaddr_inarp *
getaddr(char *host)
{
struct hostent *hp;
static struct sockaddr_inarp reply;
bzero(&reply, sizeof(reply));
reply.sin_len = sizeof(reply);
reply.sin_family = AF_INET;
reply.sin_addr.s_addr = inet_addr(host);
if (reply.sin_addr.s_addr == INADDR_NONE) {
if (!(hp = gethostbyname(host))) {
warnx("%s: %s", host, hstrerror(h_errno));
return (NULL);
}
bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
sizeof reply.sin_addr);
}
return (&reply);
}
/*
* Returns true if the type is a valid one for ARP.
*/
static int
valid_type(int type)
{
switch (type) {
case IFT_ETHER:
case IFT_FDDI:
case IFT_ISO88023:
case IFT_ISO88024:
case IFT_ISO88025:
case IFT_L2VLAN:
case IFT_BRIDGE:
return (1);
default:
return (0);
}
}
/*
* Set an individual arp entry
*/
static int
set(int argc, char **argv)
{
struct sockaddr_inarp *addr;
struct sockaddr_inarp *dst; /* what are we looking for */
struct sockaddr_dl *sdl;
struct rt_msghdr *rtm;
struct ether_addr *ea;
char *host = argv[0], *eaddr = argv[1];
struct sockaddr_dl sdl_m;
argc -= 2;
argv += 2;
bzero(&sdl_m, sizeof(sdl_m));
sdl_m.sdl_len = sizeof(sdl_m);
sdl_m.sdl_family = AF_LINK;
dst = getaddr(host);
if (dst == NULL)
return (1);
doing_proxy = flags = proxy_only = expire_time = 0;
while (argc-- > 0) {
if (strncmp(argv[0], "temp", 4) == 0) {
struct timespec tp;
int max_age;
size_t len = sizeof(max_age);
clock_gettime(CLOCK_MONOTONIC, &tp);
if (sysctlbyname("net.link.ether.inet.max_age",
&max_age, &len, NULL, 0) != 0)
err(1, "sysctlbyname");
expire_time = tp.tv_sec + max_age;
} else if (strncmp(argv[0], "pub", 3) == 0) {
flags |= RTF_ANNOUNCE;
doing_proxy = 1;
if (argc && strncmp(argv[1], "only", 3) == 0) {
proxy_only = 1;
argc--; argv++;
}
} else if (strncmp(argv[0], "blackhole", 9) == 0) {
if (flags & RTF_REJECT) {
printf("Choose one of blackhole or reject, not both.\n");
}
flags |= RTF_BLACKHOLE;
} else if (strncmp(argv[0], "reject", 6) == 0) {
if (flags & RTF_BLACKHOLE) {
printf("Choose one of blackhole or reject, not both.\n");
}
flags |= RTF_REJECT;
} else if (strncmp(argv[0], "trail", 5) == 0) {
/* XXX deprecated and undocumented feature */
printf("%s: Sending trailers is no longer supported\n",
host);
}
argv++;
}
ea = (struct ether_addr *)LLADDR(&sdl_m);
if (doing_proxy && !strcmp(eaddr, "auto")) {
if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
printf("no interface found for %s\n",
inet_ntoa(dst->sin_addr));
return (1);
}
sdl_m.sdl_alen = ETHER_ADDR_LEN;
} else {
struct ether_addr *ea1 = ether_aton(eaddr);
if (ea1 == NULL) {
warnx("invalid Ethernet address '%s'", eaddr);
return (1);
} else {
*ea = *ea1;
sdl_m.sdl_alen = ETHER_ADDR_LEN;
}
}
/*
* In the case a proxy-arp entry is being added for
* a remote end point, the RTF_ANNOUNCE flag in the
* RTM_GET command is an indication to the kernel
* routing code that the interface associated with
* the prefix route covering the local end of the
* PPP link should be returned, on which ARP applies.
*/
rtm = rtmsg(RTM_GET, dst, &sdl_m);
if (rtm == NULL) {
warn("%s", host);
return (1);
}
addr = (struct sockaddr_inarp *)(rtm + 1);
sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
if ((sdl->sdl_family != AF_LINK) ||
(rtm->rtm_flags & RTF_GATEWAY) ||
!valid_type(sdl->sdl_type)) {
printf("cannot intuit interface index and type for %s\n", host);
return (1);
}
sdl_m.sdl_type = sdl->sdl_type;
sdl_m.sdl_index = sdl->sdl_index;
return (rtmsg(RTM_ADD, dst, &sdl_m) == NULL);
}
/*
* Display an individual arp entry
*/
static int
get(char *host)
{
struct sockaddr_inarp *addr;
addr = getaddr(host);
if (addr == NULL)
return (1);
if (0 == search(addr->sin_addr.s_addr, print_entry)) {
printf("%s (%s) -- no entry",
host, inet_ntoa(addr->sin_addr));
if (rifname)
printf(" on %s", rifname);
printf("\n");
return (1);
}
return (0);
}
/*
* Delete an arp entry
*/
static int
delete(char *host, int do_proxy)
{
struct sockaddr_inarp *addr, *dst;
struct rt_msghdr *rtm;
struct sockaddr_dl *sdl;
struct sockaddr_dl sdl_m;
dst = getaddr(host);
if (dst == NULL)
return (1);
/*
* Perform a regular entry delete first.
*/
flags &= ~RTF_ANNOUNCE;
/*
* setup the data structure to notify the kernel
* it is the ARP entry the RTM_GET is interested
* in
*/
bzero(&sdl_m, sizeof(sdl_m));
sdl_m.sdl_len = sizeof(sdl_m);
sdl_m.sdl_family = AF_LINK;
for (;;) { /* try twice */
rtm = rtmsg(RTM_GET, dst, &sdl_m);
if (rtm == NULL) {
warn("%s", host);
return (1);
}
addr = (struct sockaddr_inarp *)(rtm + 1);
sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
/*
* With the new L2/L3 restructure, the route
* returned is a prefix route. The important
* piece of information from the previous
* RTM_GET is the interface index. In the
* case of ECMP, the kernel will traverse
* the route group for the given entry.
*/
if (sdl->sdl_family == AF_LINK &&
!(rtm->rtm_flags & RTF_GATEWAY) &&
valid_type(sdl->sdl_type) ) {
addr->sin_addr.s_addr = dst->sin_addr.s_addr;
break;
}
/*
* Regualar entry delete failed, now check if there
* is a proxy-arp entry to remove.
*/
if (flags & RTF_ANNOUNCE) {
fprintf(stderr, "delete: cannot locate %s\n",host);
return (1);
}
flags |= RTF_ANNOUNCE;
}
rtm->rtm_flags |= RTF_LLDATA;
if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
return (0);
}
return (1);
}
/*
* Search the arp table and do some action on matching entries
*/
static int
search(u_long addr, action_fn *action)
{
int mib[6];
size_t needed;
char *lim, *buf, *next;
struct rt_msghdr *rtm;
struct sockaddr_inarp *sin2;
struct sockaddr_dl *sdl;
char ifname[IF_NAMESIZE];
int st, found_entry = 0;
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
#ifdef RTF_LLINFO
mib[5] = RTF_LLINFO;
#else
mib[5] = 0;
#endif
if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
err(1, "route-sysctl-estimate");
if (needed == 0) /* empty table */
return 0;
buf = NULL;
for (;;) {
buf = reallocf(buf, needed);
if (buf == NULL)
errx(1, "could not reallocate memory");
st = sysctl(mib, 6, buf, &needed, NULL, 0);
if (st == 0 || errno != ENOMEM)
break;
needed += needed / 8;
}
if (st == -1)
err(1, "actual retrieval of routing table");
lim = buf + needed;
for (next = buf; next < lim; next += rtm->rtm_msglen) {
rtm = (struct rt_msghdr *)next;
sin2 = (struct sockaddr_inarp *)(rtm + 1);
sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
strcmp(ifname, rifname))
continue;
if (addr) {
if (addr != sin2->sin_addr.s_addr)
continue;
found_entry = 1;
}
(*action)(sdl, sin2, rtm);
}
free(buf);
return (found_entry);
}
/*
* Display an arp entry
*/
static char lifname[IF_NAMESIZE];
static int64_t lifindex = -1;
static void
print_entry(struct sockaddr_dl *sdl,
struct sockaddr_inarp *addr, struct rt_msghdr *rtm)
{
const char *host;
struct hostent *hp;
struct iso88025_sockaddr_dl_data *trld;
int seg;
if (nflag == 0)
hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
sizeof addr->sin_addr, AF_INET);
else
hp = 0;
if (hp)
host = hp->h_name;
else {
host = "?";
if (h_errno == TRY_AGAIN)
nflag = 1;
}
printf("%s (%s) at ", host, inet_ntoa(addr->sin_addr));
if (sdl->sdl_alen) {
if ((sdl->sdl_type == IFT_ETHER ||
sdl->sdl_type == IFT_L2VLAN ||
sdl->sdl_type == IFT_BRIDGE) &&
sdl->sdl_alen == ETHER_ADDR_LEN)
printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
else {
int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
printf("%s", link_ntoa(sdl) + n);
}
} else
printf("(incomplete)");
if (sdl->sdl_index != lifindex &&
if_indextoname(sdl->sdl_index, lifname) != NULL) {
lifindex = sdl->sdl_index;
printf(" on %s", lifname);
} else if (sdl->sdl_index == lifindex)
printf(" on %s", lifname);
if (rtm->rtm_rmx.rmx_expire == 0)
printf(" permanent");
else {
static struct timespec tp;
if (tp.tv_sec == 0)
clock_gettime(CLOCK_MONOTONIC, &tp);
if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
printf(" expires in %d seconds", (int)expire_time);
else
printf(" expired");
}
if (addr->sin_other & SIN_PROXY)
printf(" published (proxy only)");
if (rtm->rtm_flags & RTF_ANNOUNCE)
printf(" published");
switch(sdl->sdl_type) {
case IFT_ETHER:
printf(" [ethernet]");
break;
case IFT_ISO88025:
printf(" [token-ring]");
trld = SDL_ISO88025(sdl);
if (trld->trld_rcf != 0) {
printf(" rt=%x", ntohs(trld->trld_rcf));
for (seg = 0;
seg < ((TR_RCF_RIFLEN(trld->trld_rcf) - 2 ) / 2);
seg++)
printf(":%x", ntohs(*(trld->trld_route[seg])));
}
break;
case IFT_FDDI:
printf(" [fddi]");
break;
case IFT_ATM:
printf(" [atm]");
break;
case IFT_L2VLAN:
printf(" [vlan]");
break;
case IFT_IEEE1394:
printf(" [firewire]");
break;
case IFT_BRIDGE:
printf(" [bridge]");
break;
default:
break;
}
printf("\n");
}
/*
* Nuke an arp entry
*/
static void
nuke_entry(struct sockaddr_dl *sdl __unused,
struct sockaddr_inarp *addr, struct rt_msghdr *rtm __unused)
{
char ip[20];
snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
(void)delete(ip, 0);
}
static void
usage(void)
{
fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
"usage: arp [-n] [-i interface] hostname",
" arp [-n] [-i interface] -a",
" arp -d hostname [pub]",
" arp -d [-i interface] -a",
" arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
" arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
" arp -f filename");
exit(1);
}
static struct rt_msghdr *
rtmsg(int cmd, struct sockaddr_inarp *dst, struct sockaddr_dl *sdl)
{
static int seq;
int rlen;
int l;
struct sockaddr_in so_mask, *som = &so_mask;
static int s = -1;
static pid_t pid;
static struct {
struct rt_msghdr m_rtm;
char m_space[512];
} m_rtmsg;
struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
char *cp = m_rtmsg.m_space;
if (s < 0) { /* first time: open socket, get pid */
s = socket(PF_ROUTE, SOCK_RAW, 0);
if (s < 0)
err(1, "socket");
pid = getpid();
}
bzero(&so_mask, sizeof(so_mask));
so_mask.sin_len = 8;
so_mask.sin_addr.s_addr = 0xffffffff;
errno = 0;
/*
* XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
* appropriately.
*/
if (cmd == RTM_DELETE)
goto doit;
bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
rtm->rtm_flags = flags;
rtm->rtm_version = RTM_VERSION;
switch (cmd) {
default:
errx(1, "internal wrong cmd");
case RTM_ADD:
rtm->rtm_addrs |= RTA_GATEWAY;
rtm->rtm_rmx.rmx_expire = expire_time;
rtm->rtm_inits = RTV_EXPIRE;
rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
dst->sin_other = 0;
if (doing_proxy) {
if (proxy_only)
dst->sin_other = SIN_PROXY;
else {
rtm->rtm_addrs |= RTA_NETMASK;
rtm->rtm_flags &= ~RTF_HOST;
}
}
/* FALLTHROUGH */
case RTM_GET:
rtm->rtm_addrs |= RTA_DST;
}
#define NEXTADDR(w, s) \
do { \
if ((s) != NULL && rtm->rtm_addrs & (w)) { \
bcopy((s), cp, sizeof(*(s))); \
cp += SA_SIZE(s); \
} \
} while (0)
NEXTADDR(RTA_DST, dst);
NEXTADDR(RTA_GATEWAY, sdl);
NEXTADDR(RTA_NETMASK, som);
rtm->rtm_msglen = cp - (char *)&m_rtmsg;
doit:
l = rtm->rtm_msglen;
rtm->rtm_seq = ++seq;
rtm->rtm_type = cmd;
if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
if (errno != ESRCH || cmd != RTM_DELETE) {
warn("writing to routing socket");
return (NULL);
}
}
do {
l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
} while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
if (l < 0)
warn("read from routing socket");
return (rtm);
}
/*
* get_ether_addr - get the hardware address of an interface on the
* the same subnet as ipaddr.
*/
#define MAX_IFS 32
static int
get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
{
struct ifreq *ifr, *ifend, *ifp;
in_addr_t ina, mask;
struct sockaddr_dl *dla;
struct ifreq ifreq;
struct ifconf ifc;
struct ifreq ifs[MAX_IFS];
int sock;
int retval = 0;
sock = socket(AF_INET, SOCK_DGRAM, 0);
if (sock < 0)
err(1, "socket");
ifc.ifc_len = sizeof(ifs);
ifc.ifc_req = ifs;
if (ioctl(sock, SIOCGIFCONF, &ifc) < 0) {
warnx("ioctl(SIOCGIFCONF)");
goto done;
}
#define NEXTIFR(i) \
((struct ifreq *)((char *)&(i)->ifr_addr \
+ MAX((i)->ifr_addr.sa_len, sizeof((i)->ifr_addr))) )
/*
* 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; ifr = NEXTIFR(ifr) ) {
if (ifr->ifr_addr.sa_family != AF_INET)
continue;
strncpy(ifreq.ifr_name, ifr->ifr_name,
sizeof(ifreq.ifr_name));
ifreq.ifr_addr = ifr->ifr_addr;
/*
* Check that the interface is up,
* and not point-to-point or loopback.
*/
if (ioctl(sock, SIOCGIFFLAGS, &ifreq) < 0)
continue;
if ((ifreq.ifr_flags &
(IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
IFF_LOOPBACK|IFF_NOARP))
!= (IFF_UP|IFF_BROADCAST))
continue;
/*
* Get its netmask and check that it's on
* the right subnet.
*/
if (ioctl(sock, SIOCGIFNETMASK, &ifreq) < 0)
continue;
mask = ((struct sockaddr_in *)
&ifreq.ifr_addr)->sin_addr.s_addr;
ina = ((struct sockaddr_in *)
&ifr->ifr_addr)->sin_addr.s_addr;
if ((ipaddr & mask) == (ina & mask))
break; /* ok, we got it! */
}
if (ifr >= ifend)
goto done;
/*
* Now scan through again looking for a link-level address
* for this interface.
*/
ifp = ifr;
for (ifr = ifc.ifc_req; ifr < ifend; ifr = NEXTIFR(ifr))
if (strcmp(ifp->ifr_name, ifr->ifr_name) == 0 &&
ifr->ifr_addr.sa_family == AF_LINK)
break;
if (ifr >= ifend)
goto done;
/*
* Found the link-level address - copy it out
*/
dla = (struct sockaddr_dl *) &ifr->ifr_addr;
memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
printf("using interface %s for proxy with address ",
ifp->ifr_name);
printf("%s\n", ether_ntoa(hwaddr));
retval = dla->sdl_alen;
done:
close(sock);
return (retval);
}