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arp.c revision 1.58.4.1
      1 /*	$NetBSD: arp.c,v 1.58.4.1 2018/06/25 07:26:11 pgoyette Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1984, 1993
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * This code is derived from software contributed to Berkeley by
      8  * Sun Microsystems, Inc.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     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.
     21  *
     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
     32  * SUCH DAMAGE.
     33  */
     34 
     35 #include <sys/cdefs.h>
     36 #ifndef lint
     37 __COPYRIGHT("@(#) Copyright (c) 1984, 1993\
     38  The Regents of the University of California.  All rights reserved.");
     39 #endif /* not lint */
     40 
     41 #ifndef lint
     42 #if 0
     43 static char sccsid[] = "@(#)arp.c	8.3 (Berkeley) 4/28/95";
     44 #else
     45 __RCSID("$NetBSD: arp.c,v 1.58.4.1 2018/06/25 07:26:11 pgoyette Exp $");
     46 #endif
     47 #endif /* not lint */
     48 
     49 /*
     50  * arp - display, set, and delete arp table entries
     51  */
     52 
     53 #include <sys/param.h>
     54 #include <sys/file.h>
     55 #include <sys/socket.h>
     56 #include <sys/sysctl.h>
     57 #include <sys/ioctl.h>
     58 
     59 #include <net/if.h>
     60 #include <net/if_dl.h>
     61 #include <net/if_ether.h>
     62 #include <net/if_types.h>
     63 #include <net/route.h>
     64 #include <netinet/in.h>
     65 #include <netinet/if_inarp.h>
     66 #include <arpa/inet.h>
     67 
     68 #include <err.h>
     69 #include <errno.h>
     70 #include <netdb.h>
     71 #include <nlist.h>
     72 #include <paths.h>
     73 #include <stdio.h>
     74 #include <stdlib.h>
     75 #include <string.h>
     76 #include <unistd.h>
     77 #include <ifaddrs.h>
     78 
     79 #include "prog_ops.h"
     80 
     81 static int is_llinfo(const struct sockaddr_dl *, int);
     82 static int delete_one(struct rt_msghdr *);
     83 static void dump(uint32_t);
     84 static void delete(const char *, const char *);
     85 static void sdl_print(const struct sockaddr_dl *);
     86 static int getifname(u_int16_t, char *, size_t);
     87 static int atosdl(const char *s, struct sockaddr_dl *sdl);
     88 static int file(const char *);
     89 static void get(const char *);
     90 static int getinetaddr(const char *, struct in_addr *);
     91 static int getsocket(void);
     92 static struct rt_msghdr *
     93 	rtmsg(const int, const int,  struct rt_msghdr *,
     94 	    const struct sockaddr_inarp *, const struct sockaddr_dl *);
     95 static int set(int, char **);
     96 static void usage(void) __dead;
     97 
     98 static int aflag, nflag, vflag;
     99 static struct sockaddr_in so_mask = {
    100 	.sin_len = 8,
    101 	.sin_addr = {
    102 		.s_addr = 0xffffffff
    103 	}
    104 };
    105 static struct sockaddr_inarp blank_sin = {
    106 	.sin_len = sizeof(blank_sin),
    107 	.sin_family = AF_INET
    108 };
    109 static struct sockaddr_dl blank_sdl = {
    110 	.sdl_len = sizeof(blank_sdl),
    111 	.sdl_family = AF_LINK
    112 };
    113 
    114 static int expire_time, flags, export_only, doing_proxy, found_entry;
    115 
    116 int
    117 main(int argc, char **argv)
    118 {
    119 	int ch;
    120 	int op = 0;
    121 
    122 	setprogname(argv[0]);
    123 
    124 	while ((ch = getopt(argc, argv, "andsfv")) != -1)
    125 		switch((char)ch) {
    126 		case 'a':
    127 			aflag = 1;
    128 			break;
    129 		case 'd':
    130 		case 's':
    131 		case 'f':
    132 			if (op)
    133 				usage();
    134 			op = ch;
    135 			break;
    136 		case 'n':
    137 			nflag = 1;
    138 			break;
    139 		case 'v':
    140 			vflag = 1;
    141 			break;
    142 		default:
    143 			usage();
    144 		}
    145 	argc -= optind;
    146 	argv += optind;
    147 
    148 	if (!op && aflag)
    149 		op = 'a';
    150 
    151 	if (prog_init && prog_init() == -1)
    152 		err(1, "init failed");
    153 
    154 	switch((char)op) {
    155 	case 'a':
    156 		dump(0);
    157 		break;
    158 	case 'd':
    159 		if (aflag && argc == 0)
    160 			delete(NULL, NULL);
    161 		else {
    162 			if (aflag || argc < 1 || argc > 2)
    163 				usage();
    164 			delete(argv[0], argv[1]);
    165 		}
    166 		break;
    167 	case 's':
    168 		if (argc < 2 || argc > 7)
    169 			usage();
    170 		return (set(argc, argv) ? 1 : 0);
    171 	case 'f':
    172 		if (argc != 1)
    173 			usage();
    174 		return (file(argv[0]));
    175 	default:
    176 		if (argc != 1)
    177 			usage();
    178 		get(argv[0]);
    179 		break;
    180 	}
    181 	return (0);
    182 }
    183 
    184 /*
    185  * Process a file to set standard arp entries
    186  */
    187 static int
    188 file(const char *name)
    189 {
    190 	char *line, *argv[5];
    191 	int i, retval;
    192 	FILE *fp;
    193 
    194 	if (!strcmp(name, "-")) {
    195 		fp = stdin;
    196 	} else {
    197 		fp = fopen(name, "r");
    198 		if (fp == NULL) {
    199 			err(1, "Cannot open %s", name);
    200 		}
    201 	}
    202 	retval = 0;
    203 	for (; (line = fparseln(fp, NULL, NULL, NULL, 0)) != NULL; free(line)) {
    204 		char **ap, *inputstring;
    205 
    206 		inputstring = line;
    207 		for (ap = argv; ap < &argv[sizeof(argv) / sizeof(argv[0])] &&
    208 		    (*ap = stresep(&inputstring, " \t", '\\')) != NULL;) {
    209 			if (**ap != '\0')
    210 				ap++;
    211 		}
    212 		i = ap - argv;
    213 		if (i < 2) {
    214 			warnx("bad line: %s", line);
    215 			retval = 1;
    216 			continue;
    217 		}
    218 		if (set(i, argv))
    219 			retval = 1;
    220 	}
    221 	if (fp != stdin)
    222 		(void)fclose(fp);
    223 	return retval;
    224 }
    225 
    226 static int
    227 getsocket(void)
    228 {
    229 	int s;
    230 	s = prog_socket(PF_ROUTE, SOCK_RAW, 0);
    231 	if (s < 0)
    232 		err(1, "socket");
    233 	return s;
    234 }
    235 
    236 static int
    237 getlink(const char *name, struct sockaddr_dl *sdl)
    238 {
    239 	struct ifaddrs *ifap, *ifa;
    240 
    241 	if (getifaddrs(&ifap) != 0) {
    242 		warn("getifaddrs");
    243 		return 0;
    244 	}
    245 
    246 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
    247 		if (ifa->ifa_addr->sa_family != AF_LINK)
    248 			continue;
    249 		if (strcmp(ifa->ifa_name, name) != 0)
    250 			continue;
    251 		memcpy(sdl, ifa->ifa_addr, sizeof(*sdl));
    252 		freeifaddrs(ifap);
    253 		return 1;
    254 	}
    255 	freeifaddrs(ifap);
    256 	return 0;
    257 }
    258 
    259 /*
    260  * Set an individual arp entry
    261  */
    262 static int
    263 set(int argc, char **argv)
    264 {
    265 	struct sockaddr_inarp *sina;
    266 	struct sockaddr_dl *sdl = NULL;
    267 	struct rt_msghdr *rtm;
    268 	char *host = argv[0], *eaddr;
    269 	struct sockaddr_inarp sin_m = blank_sin; /* struct copy */
    270 	struct sockaddr_dl sdl_m = blank_sdl; /* struct copy */
    271 	int s;
    272 
    273 	eaddr = argv[1];
    274 
    275 	s = getsocket();
    276 	argc -= 2;
    277 	argv += 2;
    278 
    279 	if (getinetaddr(host, &sin_m.sin_addr) == -1)
    280 		return (1);
    281 	if (atosdl(eaddr, &sdl_m))
    282 		warnx("invalid link-level address '%s'", eaddr);
    283 	doing_proxy = flags = export_only = expire_time = 0;
    284 	for (; argc-- > 0; argv++) {
    285 		if (strncmp(argv[0], "temp", 4) == 0) {
    286 			struct timeval timev;
    287 			(void)gettimeofday(&timev, 0);
    288 			expire_time = timev.tv_sec + 20 * 60;
    289 		}
    290 		else if (strncmp(argv[0], "pub", 3) == 0) {
    291 			flags |= RTF_ANNOUNCE;
    292 			doing_proxy = 1;
    293 			if (argc && strncmp(argv[1], "pro", 3) == 0) {
    294 				export_only = 1;
    295 				argc--; argv++;
    296 			}
    297 		} else if (strncmp(argv[0], "trail", 5) == 0) {
    298 			warnx("%s: Sending trailers is no longer supported",
    299 			    host);
    300 		} else if (strcmp(argv[0], "ifscope") == 0) {
    301 			if (argc == 0) {
    302 				warnx("missing interface for ifscope");
    303 				continue;
    304 			}
    305 			argc--;
    306 			argv++;
    307 			if (!getlink(argv[0], &sdl_m))
    308 				warnx("cannot get link address for %s", argv[0]);
    309 		}
    310 
    311 	}
    312 tryagain:
    313 	rtm = rtmsg(s, RTM_GET, NULL, &sin_m, &sdl_m);
    314 	if (rtm == NULL) {
    315 		warn("%s", host);
    316 		return (1);
    317 	}
    318 	sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
    319 	sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) +
    320 	    (char *)(void *)sina);
    321 	if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
    322 		if (is_llinfo(sdl, rtm->rtm_flags))
    323 			goto overwrite;
    324 		if (doing_proxy == 0) {
    325 			warnx("set: can only proxy for %s", host);
    326 			return (1);
    327 		}
    328 		if (sin_m.sin_other & SIN_PROXY) {
    329 			warnx("set: proxy entry exists for non 802 device");
    330 			return (1);
    331 		}
    332 		sin_m.sin_other = SIN_PROXY;
    333 		export_only = 1;
    334 		goto tryagain;
    335 	}
    336 overwrite:
    337 	if (sdl->sdl_family != AF_LINK) {
    338 		warnx("cannot intuit interface index and type for %s",
    339 		    host);
    340 		return (1);
    341 	}
    342 	sdl_m.sdl_type = sdl->sdl_type;
    343 	sdl_m.sdl_index = sdl->sdl_index;
    344 	sin_m.sin_other = 0;
    345 	if (doing_proxy && export_only)
    346 		sin_m.sin_other = SIN_PROXY;
    347 	rtm = rtmsg(s, RTM_ADD, NULL, &sin_m, &sdl_m);
    348 	if (vflag)
    349 		(void)printf("%s (%s) added\n", host, eaddr);
    350 	return (rtm == NULL) ? 1 : 0;
    351 }
    352 
    353 /*
    354  * Display an individual arp entry
    355  */
    356 static void
    357 get(const char *host)
    358 {
    359 	struct sockaddr_inarp sin = blank_sin; /* struct copy */
    360 
    361 	if (getinetaddr(host, &sin.sin_addr) == -1)
    362 		exit(1);
    363 	dump(sin.sin_addr.s_addr);
    364 	if (found_entry == 0)
    365 		errx(1, "%s (%s) -- no entry", host, inet_ntoa(sin.sin_addr));
    366 }
    367 
    368 
    369 static int
    370 is_llinfo(const struct sockaddr_dl *sdl, int rtflags)
    371 {
    372 	if (sdl->sdl_family != AF_LINK ||
    373 	    (rtflags & (RTF_LLDATA|RTF_GATEWAY)) != RTF_LLDATA)
    374 		return 0;
    375 
    376 	switch (sdl->sdl_type) {
    377 	case IFT_ETHER:
    378 	case IFT_FDDI:
    379 	case IFT_ISO88023:
    380 	case IFT_ISO88024:
    381 	case IFT_ISO88025:
    382 	case IFT_ARCNET:
    383 		return 1;
    384 	default:
    385 		return 0;
    386 	}
    387 }
    388 
    389 /*
    390  * Delete an arp entry
    391  */
    392 int
    393 delete_one(struct rt_msghdr *rtm)
    394 {
    395 	struct sockaddr_inarp *sina;
    396 	struct sockaddr_dl *sdl;
    397 	int s;
    398 
    399 	s = getsocket();
    400 	sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
    401 	sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) +
    402 	    (char *)(void *)sina);
    403 	if (sdl->sdl_family != AF_LINK)
    404 		return (1);
    405 	rtm = rtmsg(s, RTM_DELETE, rtm, sina, sdl);
    406 	if (rtm == NULL)
    407 		return (1);
    408 	return (0);
    409 }
    410 
    411 /*
    412  * Dump the entire arp table
    413  */
    414 void
    415 dump(uint32_t addr)
    416 {
    417 	int mib[6];
    418 	size_t needed;
    419 	char ifname[IFNAMSIZ];
    420 	char *lim, *buf, *next;
    421         const char *host;
    422 	struct rt_msghdr *rtm;
    423 	struct sockaddr_inarp *sina;
    424 	struct sockaddr_dl *sdl;
    425 	struct hostent *hp;
    426 
    427 	mib[0] = CTL_NET;
    428 	mib[1] = PF_ROUTE;
    429 	mib[2] = 0;
    430 	mib[3] = AF_INET;
    431 	mib[4] = NET_RT_FLAGS;
    432 	mib[5] = 0;
    433 	if (prog_sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
    434 		err(1, "route-sysctl-estimate");
    435 	if (needed == 0)
    436 		return;
    437 	if ((buf = malloc(needed)) == NULL)
    438 		err(1, "malloc");
    439 	if (prog_sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
    440 		err(1, "actual retrieval of routing table");
    441 	lim = buf + needed;
    442 	for (next = buf; next < lim; next += rtm->rtm_msglen) {
    443 		rtm = (struct rt_msghdr *)(void *)next;
    444 		sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
    445 		sdl = (struct sockaddr_dl *)(void *)
    446 		    (RT_ROUNDUP(sina->sin_len) + (char *)(void *)sina);
    447 		if (addr) {
    448 			if (addr != sina->sin_addr.s_addr)
    449 				continue;
    450 			found_entry = 1;
    451 		}
    452 		if (nflag == 0)
    453 			hp = gethostbyaddr((const char *)(void *)
    454 			    &(sina->sin_addr),
    455 			    sizeof sina->sin_addr, AF_INET);
    456 		else
    457 			hp = NULL;
    458 
    459 		host = hp ? hp->h_name : "?";
    460 
    461 		(void)printf("%s (%s) at ", host, inet_ntoa(sina->sin_addr));
    462 		if (sdl->sdl_alen)
    463 			sdl_print(sdl);
    464 		else
    465 			(void)printf("(incomplete)");
    466 
    467 		if (sdl->sdl_index) {
    468 			if (getifname(sdl->sdl_index, ifname, sizeof(ifname)) == 0)
    469 				(void)printf(" on %s", ifname);
    470 		}
    471 
    472 		if (rtm->rtm_rmx.rmx_expire == 0)
    473 			(void)printf(" permanent");
    474 		if (sina->sin_other & SIN_PROXY)
    475 			(void)printf(" published (proxy only)");
    476 		if (rtm->rtm_addrs & RTA_NETMASK) {
    477 			sina = (struct sockaddr_inarp *)(void *)
    478 			    (RT_ROUNDUP(sdl->sdl_len) + (char *)(void *)sdl);
    479 			if (sina->sin_addr.s_addr == 0xffffffff)
    480 				(void)printf(" published");
    481 			if (sina->sin_len != 8)
    482 				(void)printf("(weird)");
    483 		}
    484 		(void)printf("\n");
    485 	}
    486 	free(buf);
    487 }
    488 
    489 /*
    490  * Delete the entire arp table
    491  */
    492 void
    493 delete(const char *host, const char *info)
    494 {
    495 	int mib[6];
    496 	size_t needed;
    497 	char *lim, *buf, *next;
    498 	struct rt_msghdr *rtm;
    499 	struct sockaddr_inarp *sina;
    500 	struct sockaddr_inarp sin_m = blank_sin; /* struct copy */
    501 
    502 	if (host != NULL) {
    503 		int ret = getinetaddr(host, &sin_m.sin_addr);
    504 		if (ret == -1)
    505 			return;
    506 	}
    507 	if (info && strncmp(info, "pro", 3) == 0)
    508 		sin_m.sin_other = SIN_PROXY;
    509 
    510 retry:
    511 	mib[0] = CTL_NET;
    512 	mib[1] = PF_ROUTE;
    513 	mib[2] = 0;
    514 	mib[3] = AF_INET;
    515 	mib[4] = NET_RT_FLAGS;
    516 	mib[5] = RTF_LLDATA;
    517 	if (prog_sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
    518 		err(1, "route-sysctl-estimate");
    519 	if (needed == 0)
    520 		return;
    521 	if ((buf = malloc(needed)) == NULL)
    522 		err(1, "malloc");
    523 	if (prog_sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
    524 		free(buf);
    525 		if (errno == ENOBUFS)
    526 			goto retry;
    527 		err(1, "actual retrieval of routing table");
    528 	}
    529 	lim = buf + needed;
    530 
    531 	for (next = buf; next < lim; next += rtm->rtm_msglen) {
    532 		int ret;
    533 		rtm = (struct rt_msghdr *)(void *)next;
    534 		sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
    535 		if (host != NULL &&
    536 		    sina->sin_addr.s_addr != sin_m.sin_addr.s_addr)
    537 			continue;
    538 		ret = delete_one(rtm);
    539 		if (vflag && ret == 0) {
    540 			(void)printf("%s (%s) deleted\n", host,
    541 			    inet_ntoa(sina->sin_addr));
    542 		}
    543 	}
    544 	free(buf);
    545 }
    546 
    547 void
    548 sdl_print(const struct sockaddr_dl *sdl)
    549 {
    550 	char hbuf[NI_MAXHOST];
    551 
    552 	if (getnameinfo((const struct sockaddr *)(const void *)sdl,
    553 	    (socklen_t)sdl->sdl_len,
    554 	    hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
    555 		(void)printf("<invalid>");
    556 	else
    557 		(void)printf("%s", hbuf);
    558 }
    559 
    560 static int
    561 atosdl(const char *ss, struct sockaddr_dl *sdl)
    562 {
    563 	int i;
    564 	unsigned long b;
    565 	char *endp;
    566 	char *p;
    567 	char *t, *r;
    568 
    569 	p = LLADDR(sdl);
    570 	endp = ((char *)(void *)sdl) + sdl->sdl_len;
    571 	i = 0;
    572 
    573 	b = strtoul(ss, &t, 16);
    574 	if (b > 255 || t == ss)
    575 		return 1;
    576 
    577 	*p++ = (char)b;
    578 	++i;
    579 	while ((p < endp) && (*t++ == ':')) {
    580 		b = strtoul(t, &r, 16);
    581 		if (b > 255 || r == t)
    582 			break;
    583 		*p++ = (char)b;
    584 		++i;
    585 		t = r;
    586 	}
    587 	sdl->sdl_alen = i;
    588 
    589 	return 0;
    590 }
    591 
    592 static void
    593 usage(void)
    594 {
    595 	const char *progname;
    596 
    597 	progname = getprogname();
    598 	(void)fprintf(stderr, "Usage: %s [-n] hostname\n", progname);
    599 	(void)fprintf(stderr, "       %s [-nv] -a\n", progname);
    600 	(void)fprintf(stderr, "       %s [-v] -d [-a|hostname [proxy]]\n",
    601 	    progname);
    602 	(void)fprintf(stderr, "       %s -s hostname ether_addr [temp] [pub [proxy]]\n",
    603 	    progname);
    604 	(void)fprintf(stderr, "       %s -f filename\n", progname);
    605 	exit(1);
    606 }
    607 
    608 static struct rt_msghdr *
    609 rtmsg(const int s, const int cmd, struct rt_msghdr *_rtm,
    610     const struct sockaddr_inarp *sin, const struct sockaddr_dl *sdl)
    611 {
    612 	static int seq;
    613 	struct rt_msghdr *rtm = _rtm;
    614 	char *cp;
    615 	int l;
    616 	static struct {
    617 		struct	rt_msghdr m_rtm;
    618 		char	m_space[512];
    619 	} m_rtmsg;
    620 	pid_t pid;
    621 
    622 	errno = 0;
    623 	if (rtm != NULL) {
    624 		memcpy(&m_rtmsg, rtm, rtm->rtm_msglen);
    625 		rtm = &m_rtmsg.m_rtm;
    626 		goto doit;
    627 	}
    628 	(void)memset(&m_rtmsg, 0, sizeof(m_rtmsg));
    629 	rtm = &m_rtmsg.m_rtm;
    630 	cp = m_rtmsg.m_space;
    631 
    632 	rtm->rtm_flags = flags;
    633 	rtm->rtm_version = RTM_VERSION;
    634 
    635 	switch (cmd) {
    636 	default:
    637 		errx(1, "internal wrong cmd");
    638 		/*NOTREACHED*/
    639 	case RTM_ADD:
    640 		rtm->rtm_addrs |= RTA_GATEWAY;
    641 		rtm->rtm_rmx.rmx_expire = expire_time;
    642 		rtm->rtm_inits = RTV_EXPIRE;
    643 		rtm->rtm_flags |= (RTF_HOST | RTF_STATIC | RTF_LLDATA);
    644 		if (doing_proxy) {
    645 			if (!export_only) {
    646 				rtm->rtm_addrs |= RTA_NETMASK;
    647 				rtm->rtm_flags &= ~RTF_HOST;
    648 			}
    649 		}
    650 		rtm->rtm_addrs |= RTA_DST;
    651 		break;
    652 	case RTM_GET:
    653 		rtm->rtm_flags |= RTF_LLDATA;
    654 		rtm->rtm_addrs |= RTA_DST | RTA_GATEWAY;
    655 	}
    656 
    657 #define NEXTADDR(w, s) \
    658 	if (rtm->rtm_addrs & (w)) { \
    659 		(void)memcpy(cp, &s, \
    660 		    (size_t)((const struct sockaddr *)&s)->sa_len); \
    661 		RT_ADVANCE(cp, ((const struct sockaddr *)&s)); \
    662 	}
    663 
    664 	NEXTADDR(RTA_DST, *sin);
    665 	NEXTADDR(RTA_GATEWAY, *sdl);
    666 	NEXTADDR(RTA_NETMASK, so_mask);
    667 
    668 	rtm->rtm_msglen = cp - (char *)(void *)&m_rtmsg;
    669 doit:
    670 	l = rtm->rtm_msglen;
    671 	rtm->rtm_seq = ++seq;
    672 	rtm->rtm_type = cmd;
    673 	if (prog_write(s, &m_rtmsg, (size_t)l) < 0) {
    674 		if (errno != ESRCH || cmd != RTM_DELETE) {
    675 			warn("writing to routing socket");
    676 			return NULL;
    677 		}
    678 	}
    679 
    680 	pid = prog_getpid();
    681 	do {
    682 		l = prog_read(s, &m_rtmsg, sizeof(m_rtmsg));
    683 	} while (l > 0 && (rtm->rtm_seq != seq || rtm->rtm_pid != pid));
    684 	if (l < 0)
    685 		warn("read from routing socket");
    686 	return rtm;
    687 }
    688 
    689 static int
    690 getinetaddr(const char *host, struct in_addr *inap)
    691 {
    692 	struct hostent *hp;
    693 
    694 	if (inet_aton(host, inap) == 1)
    695 		return (0);
    696 	if ((hp = gethostbyname(host)) == NULL) {
    697 		warnx("%s: %s", host, hstrerror(h_errno));
    698 		return (-1);
    699 	}
    700 	(void)memcpy(inap, hp->h_addr, sizeof(*inap));
    701 	return (0);
    702 }
    703 
    704 static int
    705 getifname(u_int16_t ifindex, char *ifname, size_t l)
    706 {
    707 	int i;
    708 	struct ifaddrs *addr;
    709 	const struct sockaddr_dl *sdl = NULL;
    710 	static struct ifaddrs* ifaddrs = NULL;
    711 
    712 	if (ifaddrs == NULL) {
    713 		i = getifaddrs(&ifaddrs);
    714 		if (i != 0)
    715 			err(1, "getifaddrs");
    716 	}
    717 
    718 	for (addr = ifaddrs; addr; addr = addr->ifa_next) {
    719 		if (addr->ifa_addr == NULL ||
    720 		    addr->ifa_addr->sa_family != AF_LINK)
    721 			continue;
    722 
    723 		sdl = (const struct sockaddr_dl *)(void *)addr->ifa_addr;
    724 		if (sdl && sdl->sdl_index == ifindex) {
    725 			(void) strlcpy(ifname, addr->ifa_name, l);
    726 			return 0;
    727 		}
    728 	}
    729 
    730 	return -1;
    731 }
    732