2 * SPDX-License-Identifier: BSD-3-Clause
4 * Copyright (c) 1984, 1993
5 * The Regents of the University of California. All rights reserved.
7 * This code is derived from software contributed to Berkeley by
8 * Sun Microsystems, Inc.
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 * 3. Neither the name of the University nor the names of its contributors
19 * may be used to endorse or promote products derived from this software
20 * without specific prior written permission.
22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37 static char const copyright[] =
38 "@(#) Copyright (c) 1984, 1993\n\
39 The Regents of the University of California. All rights reserved.\n";
43 static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
46 #include <sys/cdefs.h>
47 __FBSDID("$FreeBSD$");
50 * arp - display, set, and delete arp table entries
53 #include <sys/param.h>
55 #include <sys/socket.h>
56 #include <sys/sockio.h>
57 #include <sys/sysctl.h>
58 #include <sys/ioctl.h>
62 #include <net/if_dl.h>
63 #include <net/if_types.h>
64 #include <net/route.h>
66 #include <netinet/in.h>
67 #include <netinet/if_ether.h>
69 #include <arpa/inet.h>
87 typedef void (action_fn)(struct sockaddr_dl *sdl, struct sockaddr_in *s_in,
88 struct rt_msghdr *rtm);
89 static void nuke_entries(uint32_t ifindex, struct in_addr addr);
90 static int print_entries(uint32_t ifindex, struct in_addr addr);
92 static int delete(char *host);
93 static void usage(void);
94 static int set(int argc, char **argv);
95 static int get(char *host);
96 static int file(char *name);
97 static struct rt_msghdr *rtmsg(int cmd,
98 struct sockaddr_in *dst, struct sockaddr_dl *sdl);
99 static int get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr);
100 static int set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m,
103 static char *rifname;
105 struct if_nameindex *ifnameindex;
107 struct arp_opts opts = {};
109 /* which function we're supposed to do */
116 #define SETFUNC(f) { if (func) usage(); func = (f); }
118 #define ARP_XO_VERSION "1"
121 main(int argc, char *argv[])
126 argc = xo_parse_args(argc, argv);
130 while ((ch = getopt(argc, argv, "andfsSi:")) != -1)
163 if (func != F_GET && !(func == F_DELETE && opts.aflag))
164 xo_errx(1, "-i not applicable to this operation");
165 if (if_nametoindex(rifname) == 0) {
167 xo_errx(1, "interface %s does not exist",
170 xo_err(1, "if_nametoindex(%s)", rifname);
179 xo_set_version(ARP_XO_VERSION);
180 xo_open_container("arp");
181 xo_open_list("arp-cache");
183 struct in_addr all_addrs = {};
184 print_entries(0, all_addrs);
186 xo_close_list("arp-cache");
187 xo_close_container("arp");
197 if (argc < 2 || argc > 6)
199 if (func == F_REPLACE)
200 (void)delete(argv[0]);
201 rtn = set(argc, argv) ? 1 : 0;
207 struct in_addr all_addrs = {};
208 nuke_entries(0, all_addrs);
212 rtn = delete(argv[0]);
222 if (ifnameindex != NULL)
223 if_freenameindex(ifnameindex);
229 * Process a file to set standard arp entries
236 char line[100], arg[5][50], *args[5], *p;
238 if ((fp = fopen(name, "r")) == NULL)
239 xo_err(1, "cannot open %s", name);
240 args[0] = &arg[0][0];
241 args[1] = &arg[1][0];
242 args[2] = &arg[2][0];
243 args[3] = &arg[3][0];
244 args[4] = &arg[4][0];
246 while(fgets(line, sizeof(line), fp) != NULL) {
247 if ((p = strchr(line, '#')) != NULL)
249 for (p = line; isblank(*p); p++);
250 if (*p == '\n' || *p == '\0')
252 i = sscanf(p, "%49s %49s %49s %49s %49s", arg[0], arg[1],
253 arg[2], arg[3], arg[4]);
255 xo_warnx("bad line: %s", line);
267 * Given a hostname, fills up a (static) struct sockaddr_in with
268 * the address of the host and returns a pointer to the
275 static struct sockaddr_in reply;
277 bzero(&reply, sizeof(reply));
278 reply.sin_len = sizeof(reply);
279 reply.sin_family = AF_INET;
280 reply.sin_addr.s_addr = inet_addr(host);
281 if (reply.sin_addr.s_addr == INADDR_NONE) {
282 if (!(hp = gethostbyname(host))) {
283 xo_warnx("%s: %s", host, hstrerror(h_errno));
286 bcopy((char *)hp->h_addr, (char *)&reply.sin_addr,
287 sizeof reply.sin_addr);
292 int valid_type(int type);
294 * Returns true if the type is a valid one for ARP.
316 * Set an individual arp entry
319 set(int argc, char **argv)
321 struct sockaddr_in *dst; /* what are we looking for */
322 struct ether_addr *ea;
323 char *host = argv[0], *eaddr = argv[1];
324 struct sockaddr_dl sdl_m;
329 bzero(&sdl_m, sizeof(sdl_m));
330 sdl_m.sdl_len = sizeof(sdl_m);
331 sdl_m.sdl_family = AF_LINK;
337 if (strcmp(argv[0], "temp") == 0) {
339 size_t len = sizeof(max_age);
341 if (sysctlbyname("net.link.ether.inet.max_age",
342 &max_age, &len, NULL, 0) != 0)
343 xo_err(1, "sysctlbyname");
344 opts.expire_time = max_age;
345 } else if (strcmp(argv[0], "pub") == 0) {
346 opts.flags |= RTF_ANNOUNCE;
347 if (argc && strcmp(argv[1], "only") == 0) {
349 * Compatibility: in pre FreeBSD 8 times
350 * the "only" keyword used to mean that
351 * an ARP entry should be announced, but
352 * not installed into routing table.
356 } else if (strcmp(argv[0], "blackhole") == 0) {
357 if (opts.flags & RTF_REJECT) {
358 xo_errx(1, "Choose one of blackhole or reject, "
361 opts.flags |= RTF_BLACKHOLE;
362 } else if (strcmp(argv[0], "reject") == 0) {
363 if (opts.flags & RTF_BLACKHOLE) {
364 xo_errx(1, "Choose one of blackhole or reject, "
367 opts.flags |= RTF_REJECT;
369 xo_warnx("Invalid parameter '%s'", argv[0]);
374 ea = (struct ether_addr *)LLADDR(&sdl_m);
375 if ((opts.flags & RTF_ANNOUNCE) && !strcmp(eaddr, "auto")) {
376 if (!get_ether_addr(dst->sin_addr.s_addr, ea)) {
377 xo_warnx("no interface found for %s",
378 inet_ntoa(dst->sin_addr));
381 sdl_m.sdl_alen = ETHER_ADDR_LEN;
383 struct ether_addr *ea1 = ether_aton(eaddr);
386 xo_warnx("invalid Ethernet address '%s'", eaddr);
390 sdl_m.sdl_alen = ETHER_ADDR_LEN;
393 #ifndef WITHOUT_NETLINK
394 return (set_nl(0, dst, &sdl_m, host));
396 return (set_rtsock(dst, &sdl_m, host));
400 #ifdef WITHOUT_NETLINK
402 set_rtsock(struct sockaddr_in *dst, struct sockaddr_dl *sdl_m, char *host)
404 struct sockaddr_in *addr;
405 struct sockaddr_dl *sdl;
406 struct rt_msghdr *rtm;
409 * In the case a proxy-arp entry is being added for
410 * a remote end point, the RTF_ANNOUNCE flag in the
411 * RTM_GET command is an indication to the kernel
412 * routing code that the interface associated with
413 * the prefix route covering the local end of the
414 * PPP link should be returned, on which ARP applies.
416 rtm = rtmsg(RTM_GET, dst, NULL);
421 addr = (struct sockaddr_in *)(rtm + 1);
422 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
424 if ((sdl->sdl_family != AF_LINK) ||
425 (rtm->rtm_flags & RTF_GATEWAY) ||
426 !valid_type(sdl->sdl_type)) {
427 xo_warnx("cannot intuit interface index and type for %s", host);
430 sdl_m->sdl_type = sdl->sdl_type;
431 sdl_m->sdl_index = sdl->sdl_index;
432 return (rtmsg(RTM_ADD, dst, sdl_m) == NULL);
437 * Display an individual arp entry
442 struct sockaddr_in *addr;
445 addr = getaddr(host);
449 xo_set_version(ARP_XO_VERSION);
450 xo_open_container("arp");
451 xo_open_list("arp-cache");
453 found = print_entries(0, addr->sin_addr);
456 xo_emit("{d:hostname/%s} ({d:ip-address/%s}) -- no entry",
457 host, inet_ntoa(addr->sin_addr));
459 xo_emit(" on {d:interface/%s}", rifname);
463 xo_close_list("arp-cache");
464 xo_close_container("arp");
471 * Delete an arp entry
473 #ifdef WITHOUT_NETLINK
475 delete_rtsock(char *host)
477 struct sockaddr_in *addr, *dst;
478 struct rt_msghdr *rtm;
479 struct sockaddr_dl *sdl;
486 * Perform a regular entry delete first.
488 opts.flags &= ~RTF_ANNOUNCE;
490 for (;;) { /* try twice */
491 rtm = rtmsg(RTM_GET, dst, NULL);
496 addr = (struct sockaddr_in *)(rtm + 1);
497 sdl = (struct sockaddr_dl *)(SA_SIZE(addr) + (char *)addr);
500 * With the new L2/L3 restructure, the route
501 * returned is a prefix route. The important
502 * piece of information from the previous
503 * RTM_GET is the interface index. In the
504 * case of ECMP, the kernel will traverse
505 * the route group for the given entry.
507 if (sdl->sdl_family == AF_LINK &&
508 !(rtm->rtm_flags & RTF_GATEWAY) &&
509 valid_type(sdl->sdl_type) ) {
510 addr->sin_addr.s_addr = dst->sin_addr.s_addr;
515 * Regular entry delete failed, now check if there
516 * is a proxy-arp entry to remove.
518 if (opts.flags & RTF_ANNOUNCE) {
519 xo_warnx("delete: cannot locate %s", host);
523 opts.flags |= RTF_ANNOUNCE;
525 rtm->rtm_flags |= RTF_LLDATA;
526 if (rtmsg(RTM_DELETE, dst, NULL) != NULL) {
527 printf("%s (%s) deleted\n", host, inet_ntoa(addr->sin_addr));
537 #ifdef WITHOUT_NETLINK
538 return (delete_rtsock(host));
540 return (delete_nl(0, host));
546 * Search the arp table and do some action on matching entries
549 search(u_long addr, action_fn *action)
553 char *lim, *buf, *next;
554 struct rt_msghdr *rtm;
555 struct sockaddr_in *sin2;
556 struct sockaddr_dl *sdl;
557 char ifname[IF_NAMESIZE];
558 int st, found_entry = 0;
564 mib[4] = NET_RT_FLAGS;
570 if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
571 xo_err(1, "route-sysctl-estimate");
572 if (needed == 0) /* empty table */
576 buf = reallocf(buf, needed);
578 xo_errx(1, "could not reallocate memory");
579 st = sysctl(mib, 6, buf, &needed, NULL, 0);
580 if (st == 0 || errno != ENOMEM)
582 needed += needed / 8;
585 xo_err(1, "actual retrieval of routing table");
587 for (next = buf; next < lim; next += rtm->rtm_msglen) {
588 rtm = (struct rt_msghdr *)next;
589 sin2 = (struct sockaddr_in *)(rtm + 1);
590 sdl = (struct sockaddr_dl *)((char *)sin2 + SA_SIZE(sin2));
591 if (rifname && if_indextoname(sdl->sdl_index, ifname) &&
592 strcmp(ifname, rifname))
595 if (addr != sin2->sin_addr.s_addr)
599 (*action)(sdl, sin2, rtm);
602 return (found_entry);
606 * Display an arp entry
610 print_entry(struct sockaddr_dl *sdl,
611 struct sockaddr_in *addr, struct rt_msghdr *rtm)
615 struct if_nameindex *p;
617 if (ifnameindex == NULL)
618 if ((ifnameindex = if_nameindex()) == NULL)
619 xo_err(1, "cannot retrieve interface names");
621 xo_open_instance("arp-cache");
624 hp = gethostbyaddr((caddr_t)&(addr->sin_addr),
625 sizeof addr->sin_addr, AF_INET);
632 if (h_errno == TRY_AGAIN)
635 xo_emit("{:hostname/%s} ({:ip-address/%s}) at ", host,
636 inet_ntoa(addr->sin_addr));
638 if ((sdl->sdl_type == IFT_ETHER ||
639 sdl->sdl_type == IFT_L2VLAN ||
640 sdl->sdl_type == IFT_BRIDGE) &&
641 sdl->sdl_alen == ETHER_ADDR_LEN)
642 xo_emit("{:mac-address/%s}",
643 ether_ntoa((struct ether_addr *)LLADDR(sdl)));
645 int n = sdl->sdl_nlen > 0 ? sdl->sdl_nlen + 1 : 0;
647 xo_emit("{:mac-address/%s}", link_ntoa(sdl) + n);
650 xo_emit("{d:/(incomplete)}{en:incomplete/true}");
652 for (p = ifnameindex; p && p->if_index && p->if_name; p++) {
653 if (p->if_index == sdl->sdl_index) {
654 xo_emit(" on {:interface/%s}", p->if_name);
659 if (rtm->rtm_rmx.rmx_expire == 0)
660 xo_emit("{d:/ permanent}{en:permanent/true}");
662 static struct timespec tp;
663 time_t expire_time = 0;
666 clock_gettime(CLOCK_MONOTONIC, &tp);
667 if ((expire_time = rtm->rtm_rmx.rmx_expire - tp.tv_sec) > 0)
668 xo_emit(" expires in {:expires/%d} seconds",
671 xo_emit("{d:/ expired}{en:expired/true}");
674 if (rtm->rtm_flags & RTF_ANNOUNCE)
675 xo_emit("{d:/ published}{en:published/true}");
677 switch(sdl->sdl_type) {
679 xo_emit(" [{:type/ethernet}]");
682 xo_emit(" [{:type/fddi}]");
685 xo_emit(" [{:type/atm}]");
688 xo_emit(" [{:type/vlan}]");
691 xo_emit(" [{:type/firewire}]");
694 xo_emit(" [{:type/bridge}]");
697 xo_emit(" [{:type/infiniband}]");
705 xo_close_instance("arp-cache");
709 print_entries(uint32_t ifindex, struct in_addr addr)
711 #ifndef WITHOUT_NETLINK
712 return (print_entries_nl(ifindex, addr));
714 return (search(addr.s_addr, print_entry));
723 nuke_entry(struct sockaddr_dl *sdl __unused,
724 struct sockaddr_in *addr, struct rt_msghdr *rtm)
728 if (rtm->rtm_flags & RTF_PINNED)
731 snprintf(ip, sizeof(ip), "%s", inet_ntoa(addr->sin_addr));
736 nuke_entries(uint32_t ifindex, struct in_addr addr)
738 search(addr.s_addr, nuke_entry);
744 fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
745 "usage: arp [-n] [-i interface] hostname",
746 " arp [-n] [-i interface] -a",
747 " arp -d hostname [pub]",
748 " arp -d [-i interface] -a",
749 " arp -s hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
750 " arp -S hostname ether_addr [temp] [reject | blackhole] [pub [only]]",
755 static struct rt_msghdr *
756 rtmsg(int cmd, struct sockaddr_in *dst, struct sockaddr_dl *sdl)
765 struct rt_msghdr m_rtm;
769 struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
770 char *cp = m_rtmsg.m_space;
772 if (s < 0) { /* first time: open socket, get pid */
773 s = socket(PF_ROUTE, SOCK_RAW, 0);
781 * XXX RTM_DELETE relies on a previous RTM_GET to fill the buffer
784 if (cmd == RTM_DELETE)
786 bzero((char *)&m_rtmsg, sizeof(m_rtmsg));
787 rtm->rtm_flags = opts.flags;
788 rtm->rtm_version = RTM_VERSION;
792 xo_errx(1, "internal wrong cmd");
794 rtm->rtm_addrs |= RTA_GATEWAY;
795 if (opts.expire_time != 0) {
798 clock_gettime(CLOCK_MONOTONIC, &tp);
799 rtm->rtm_rmx.rmx_expire = opts.expire_time + tp.tv_sec;
801 rtm->rtm_inits = RTV_EXPIRE;
802 rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
805 rtm->rtm_addrs |= RTA_DST;
807 #define NEXTADDR(w, s) \
809 if ((s) != NULL && rtm->rtm_addrs & (w)) { \
810 bcopy((s), cp, sizeof(*(s))); \
815 NEXTADDR(RTA_DST, dst);
816 NEXTADDR(RTA_GATEWAY, sdl);
818 rtm->rtm_msglen = cp - (char *)&m_rtmsg;
821 rtm->rtm_seq = ++seq;
823 if ((rlen = write(s, (char *)&m_rtmsg, l)) < 0) {
824 if (errno != ESRCH || cmd != RTM_DELETE) {
825 xo_warn("writing to routing socket");
830 l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
831 } while (l > 0 && (rtm->rtm_type != cmd || rtm->rtm_seq != seq ||
832 rtm->rtm_pid != pid));
834 xo_warn("read from routing socket");
839 * get_ether_addr - get the hardware address of an interface on the
840 * the same subnet as ipaddr.
843 get_ether_addr(in_addr_t ipaddr, struct ether_addr *hwaddr)
845 struct ifaddrs *ifa, *ifd, *ifas = NULL;
847 struct sockaddr_dl *dla;
851 * Scan through looking for an interface with an Internet
852 * address on the same subnet as `ipaddr'.
854 if (getifaddrs(&ifas) < 0) {
855 xo_warnx("getifaddrs");
859 for (ifa = ifas; ifa != NULL; ifa = ifa->ifa_next) {
860 if (ifa->ifa_addr == NULL || ifa->ifa_netmask == NULL)
862 if (ifa->ifa_addr->sa_family != AF_INET)
865 * Check that the interface is up,
866 * and not point-to-point or loopback.
868 if ((ifa->ifa_flags &
869 (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
870 IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST))
872 /* Get its netmask and check that it's on the right subnet. */
873 mask = ((struct sockaddr_in *)
874 ifa->ifa_netmask)->sin_addr.s_addr;
875 ina = ((struct sockaddr_in *)
876 ifa->ifa_addr)->sin_addr.s_addr;
877 if ((ipaddr & mask) == (ina & mask))
878 break; /* ok, we got it! */
884 * Now scan through again looking for a link-level address
885 * for this interface.
887 for (ifd = ifas; ifd != NULL; ifd = ifd->ifa_next) {
888 if (ifd->ifa_addr == NULL)
890 if (strcmp(ifa->ifa_name, ifd->ifa_name) == 0 &&
891 ifd->ifa_addr->sa_family == AF_LINK)
897 * Found the link-level address - copy it out
899 dla = (struct sockaddr_dl *)ifd->ifa_addr;
900 memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
901 printf("using interface %s for proxy with address %s\n", ifa->ifa_name,
903 retval = dla->sdl_alen;