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NetBSD/usr.sbin/arp/arp.c

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/* $NetBSD: arp.c,v 1.65 2019/02/28 01:20:25 nonaka Exp $ */
/*
* 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.
* 3. 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1984, 1993\
The Regents of the University of California. All rights reserved.");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)arp.c 8.3 (Berkeley) 4/28/95";
#else
__RCSID("$NetBSD: arp.c,v 1.65 2019/02/28 01:20:25 nonaka Exp $");
#endif
#endif /* not lint */
/*
* arp - display, set, and delete arp table entries
*/
#include <sys/param.h>
#include <sys/file.h>
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/ioctl.h>
#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_ether.h>
#include <net/if_types.h>
#include <net/route.h>
#include <netinet/in.h>
#include <netinet/if_inarp.h>
#include <arpa/inet.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 <unistd.h>
#include <ifaddrs.h>
#include "prog_ops.h"
static int is_llinfo(const struct sockaddr_dl *, int);
static int delete_one(struct rt_msghdr *);
static void dump(uint32_t);
static void delete(const char *, const char *);
static void sdl_print(const struct sockaddr_dl *);
static int getifname(u_int16_t, char *, size_t);
static int atosdl(const char *, struct sockaddr_dl *);
static int file(const char *);
static void get(const char *);
static int getinetaddr(const char *, struct in_addr *);
static int getsocket(void);
static int getetheraddr(struct in_addr, struct sockaddr_dl *);
static struct rt_msghdr * rtmsg(const int, const int, struct rt_msghdr *,
const struct sockaddr_inarp *, const struct sockaddr_dl *);
static int set(int, char **);
static void usage(void) __dead;
static int aflag, nflag, vflag;
static struct sockaddr_in so_mask = {
.sin_len = 8,
.sin_addr = {
.s_addr = 0xffffffff
}
};
static struct sockaddr_inarp blank_sin = {
.sin_len = sizeof(blank_sin),
.sin_family = AF_INET
};
static struct sockaddr_dl blank_sdl = {
.sdl_len = sizeof(blank_sdl),
.sdl_family = AF_LINK
};
static int expire_time, flags, export_only, doing_proxy, found_entry;
int
main(int argc, char **argv)
{
int ch;
int op = 0;
setprogname(argv[0]);
while ((ch = getopt(argc, argv, "andsfv")) != -1)
switch((char)ch) {
case 'a':
aflag = 1;
break;
case 'd':
case 's':
case 'f':
if (op)
usage();
op = ch;
break;
case 'n':
nflag = 1;
break;
case 'v':
vflag = 1;
break;
default:
usage();
}
argc -= optind;
argv += optind;
if (!op && aflag)
op = 'a';
if (prog_init && prog_init() == -1)
err(1, "init failed");
switch((char)op) {
case 'a':
dump(0);
break;
case 'd':
if (aflag && argc == 0)
delete(NULL, NULL);
else {
if (aflag || argc < 1 || argc > 2)
usage();
delete(argv[0], argv[1]);
}
break;
case 's':
if (argc < 2 || argc > 7)
usage();
return (set(argc, argv) ? 1 : 0);
case 'f':
if (argc != 1)
usage();
return (file(argv[0]));
default:
if (argc != 1)
usage();
get(argv[0]);
break;
}
return (0);
}
/*
* Process a file to set standard arp entries
*/
static int
file(const char *name)
{
char *line, *argv[5];
int i, retval;
FILE *fp;
if (!strcmp(name, "-")) {
fp = stdin;
} else {
fp = fopen(name, "r");
if (fp == NULL) {
err(1, "Cannot open %s", name);
}
}
retval = 0;
for (; (line = fparseln(fp, NULL, NULL, NULL, 0)) != NULL; free(line)) {
char **ap, *inputstring;
inputstring = line;
for (ap = argv; ap < &argv[sizeof(argv) / sizeof(argv[0])] &&
(*ap = stresep(&inputstring, " \t", '\\')) != NULL;) {
if (**ap != '\0')
ap++;
}
i = ap - argv;
if (i < 2) {
warnx("bad line: %s", line);
retval = 1;
continue;
}
if (set(i, argv))
retval = 1;
}
if (fp != stdin)
(void)fclose(fp);
return retval;
}
static int
getsocket(void)
{
int s;
s = prog_socket(PF_ROUTE, SOCK_RAW, 0);
if (s < 0)
err(1, "socket");
return s;
}
static int
getlink(const char *name, struct sockaddr_dl *sdl)
{
struct ifaddrs *ifap, *ifa;
if (getifaddrs(&ifap) != 0) {
warn("getifaddrs");
return 0;
}
for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
if (ifa->ifa_addr->sa_family != AF_LINK)
continue;
if (strcmp(ifa->ifa_name, name) != 0)
continue;
memcpy(sdl, ifa->ifa_addr, sizeof(*sdl));
freeifaddrs(ifap);
return 1;
}
freeifaddrs(ifap);
return 0;
}
/*
* Set an individual arp entry
*/
static int
set(int argc, char **argv)
{
struct sockaddr_inarp *sina;
struct sockaddr_dl *sdl = NULL;
struct rt_msghdr *rtm;
char *host = argv[0], *eaddr;
struct sockaddr_inarp sin_m = blank_sin; /* struct copy */
struct sockaddr_dl sdl_m = blank_sdl; /* struct copy */
int s;
eaddr = argv[1];
s = getsocket();
argc -= 2;
argv += 2;
if (getinetaddr(host, &sin_m.sin_addr) == -1) {
prog_close(s);
return (1);
}
if (strcmp(eaddr, "auto") != 0 && atosdl(eaddr, &sdl_m))
warnx("invalid link-level address '%s'", eaddr);
doing_proxy = flags = export_only = expire_time = 0;
for (; argc-- > 0; argv++) {
if (strncmp(argv[0], "temp", 4) == 0) {
struct timeval timev;
(void)gettimeofday(&timev, 0);
expire_time = timev.tv_sec + 20 * 60;
}
else if (strncmp(argv[0], "pub", 3) == 0) {
flags |= RTF_ANNOUNCE;
doing_proxy = 1;
if (argc && strncmp(argv[1], "pro", 3) == 0) {
export_only = 1;
argc--; argv++;
}
} else if (strncmp(argv[0], "trail", 5) == 0) {
warnx("%s: Sending trailers is no longer supported",
host);
} else if (strcmp(argv[0], "ifscope") == 0) {
if (argc == 0) {
warnx("missing interface for ifscope");
continue;
}
argc--;
argv++;
if (!getlink(argv[0], &sdl_m))
warnx("cannot get link address for %s", argv[0]);
}
}
if (doing_proxy && strcmp(eaddr, "auto") == 0) {
if (getetheraddr(sin_m.sin_addr, &sdl_m) == -1) {
prog_close(s);
return 1;
}
}
tryagain:
rtm = rtmsg(s, RTM_GET, NULL, &sin_m, &sdl_m);
if (rtm == NULL) {
warn("%s", host);
prog_close(s);
return (1);
}
sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) +
(char *)(void *)sina);
if (sina->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
if (is_llinfo(sdl, rtm->rtm_flags))
goto overwrite;
if (doing_proxy == 0) {
warnx("set: can only proxy for %s", host);
prog_close(s);
return (1);
}
if (sin_m.sin_other & SIN_PROXY) {
warnx("set: proxy entry exists for non 802 device");
prog_close(s);
return (1);
}
sin_m.sin_other = SIN_PROXY;
export_only = 1;
goto tryagain;
}
overwrite:
if (sdl->sdl_family != AF_LINK) {
warnx("cannot intuit interface index and type for %s",
host);
prog_close(s);
return (1);
}
sdl_m.sdl_type = sdl->sdl_type;
sdl_m.sdl_index = sdl->sdl_index;
sin_m.sin_other = 0;
if (doing_proxy && export_only)
sin_m.sin_other = SIN_PROXY;
rtm = rtmsg(s, RTM_ADD, NULL, &sin_m, &sdl_m);
if (vflag)
(void)printf("%s (%s) added\n", host, eaddr);
prog_close(s);
return (rtm == NULL) ? 1 : 0;
}
/*
* Display an individual arp entry
*/
static void
get(const char *host)
{
struct sockaddr_inarp sin = blank_sin; /* struct copy */
if (getinetaddr(host, &sin.sin_addr) == -1)
exit(1);
dump(sin.sin_addr.s_addr);
if (found_entry == 0)
errx(1, "%s (%s) -- no entry", host, inet_ntoa(sin.sin_addr));
}
static int
is_llinfo(const struct sockaddr_dl *sdl, int rtflags)
{
if (sdl->sdl_family != AF_LINK ||
(rtflags & (RTF_LLDATA|RTF_GATEWAY)) != RTF_LLDATA)
return 0;
switch (sdl->sdl_type) {
case IFT_ETHER:
case IFT_FDDI:
case IFT_ISO88023:
case IFT_ISO88024:
case IFT_ISO88025:
case IFT_ARCNET:
return 1;
default:
return 0;
}
}
/*
* Delete an arp entry
*/
int
delete_one(struct rt_msghdr *rtm)
{
struct sockaddr_inarp *sina;
struct sockaddr_dl *sdl;
int s;
s = getsocket();
sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
sdl = (struct sockaddr_dl *)(void *)(RT_ROUNDUP(sina->sin_len) +
(char *)(void *)sina);
if (sdl->sdl_family != AF_LINK) {
prog_close(s);
return (1);
}
rtm = rtmsg(s, RTM_DELETE, rtm, sina, sdl);
prog_close(s);
if (rtm == NULL)
return (1);
return (0);
}
/*
* Dump the entire arp table
*/
void
dump(uint32_t addr)
{
int mib[6];
size_t needed;
char ifname[IFNAMSIZ];
char *lim, *buf, *next;
const char *host;
struct rt_msghdr *rtm;
struct sockaddr_inarp *sina;
struct sockaddr_dl *sdl;
struct hostent *hp;
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
mib[5] = 0;
if (prog_sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
err(1, "route-sysctl-estimate");
if (needed == 0)
return;
if ((buf = malloc(needed)) == NULL)
err(1, "malloc");
if (prog_sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
err(1, "actual retrieval of routing table");
lim = buf + needed;
for (next = buf; next < lim; next += rtm->rtm_msglen) {
rtm = (struct rt_msghdr *)(void *)next;
sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
sdl = (struct sockaddr_dl *)(void *)
(RT_ROUNDUP(sina->sin_len) + (char *)(void *)sina);
if (addr) {
if (addr != sina->sin_addr.s_addr)
continue;
found_entry = 1;
}
if (nflag == 0)
hp = gethostbyaddr((const char *)(void *)
&(sina->sin_addr),
sizeof sina->sin_addr, AF_INET);
else
hp = NULL;
host = hp ? hp->h_name : "?";
(void)printf("%s (%s) at ", host, inet_ntoa(sina->sin_addr));
if (sdl->sdl_alen)
sdl_print(sdl);
else
(void)printf("(incomplete)");
if (sdl->sdl_index) {
if (getifname(sdl->sdl_index, ifname, sizeof(ifname)) == 0)
(void)printf(" on %s", ifname);
}
if (rtm->rtm_rmx.rmx_expire == 0)
(void)printf(" permanent");
if (sina->sin_other & SIN_PROXY)
(void)printf(" published (proxy only)");
if (rtm->rtm_addrs & RTA_NETMASK) {
sina = (struct sockaddr_inarp *)(void *)
(RT_ROUNDUP(sdl->sdl_len) + (char *)(void *)sdl);
if (sina->sin_addr.s_addr == 0xffffffff)
(void)printf(" published");
if (sina->sin_len != 8)
(void)printf("(weird)");
}
(void)printf("\n");
}
free(buf);
}
/*
* Delete the entire arp table
*/
void
delete(const char *host, const char *info)
{
int mib[6];
char addr[sizeof("000.000.000.000\0")];
size_t needed;
char *lim, *buf, *next;
struct rt_msghdr *rtm;
struct sockaddr_inarp *sina;
struct sockaddr_inarp sin_m = blank_sin; /* struct copy */
bool found = false;
if (host != NULL) {
int ret = getinetaddr(host, &sin_m.sin_addr);
if (ret == -1)
return;
}
if (info && strncmp(info, "pro", 3) == 0)
sin_m.sin_other = SIN_PROXY;
retry:
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
mib[5] = RTF_LLDATA;
if (prog_sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
err(1, "route-sysctl-estimate");
if (needed == 0)
return;
if ((buf = malloc(needed)) == NULL)
err(1, "malloc");
if (prog_sysctl(mib, 6, buf, &needed, NULL, 0) < 0) {
free(buf);
if (errno == ENOBUFS)
goto retry;
err(1, "actual retrieval of routing table");
}
lim = buf + needed;
for (next = buf; next < lim; next += rtm->rtm_msglen) {
int ret;
rtm = (struct rt_msghdr *)(void *)next;
sina = (struct sockaddr_inarp *)(void *)(rtm + 1);
if (host != NULL &&
sina->sin_addr.s_addr != sin_m.sin_addr.s_addr)
continue;
found = true;
ret = delete_one(rtm);
if (vflag && ret == 0) {
snprintf(addr, sizeof(addr), "%s",
inet_ntoa(sina->sin_addr));
(void)printf("%s (%s) deleted\n",
host != NULL ? host : addr, addr);
}
}
if (host != NULL && !found)
warnx("delete: can't locate %s", host);
free(buf);
}
void
sdl_print(const struct sockaddr_dl *sdl)
{
char hbuf[NI_MAXHOST];
if (getnameinfo((const struct sockaddr *)(const void *)sdl,
(socklen_t)sdl->sdl_len,
hbuf, sizeof(hbuf), NULL, 0, NI_NUMERICHOST) != 0)
(void)printf("<invalid>");
else
(void)printf("%s", hbuf);
}
static int
atosdl(const char *ss, struct sockaddr_dl *sdl)
{
int i;
unsigned long b;
char *endp;
char *p;
char *t, *r;
p = LLADDR(sdl);
endp = ((char *)(void *)sdl) + sdl->sdl_len;
i = 0;
b = strtoul(ss, &t, 16);
if (b > 255 || t == ss)
return 1;
*p++ = (char)b;
++i;
while ((p < endp) && (*t++ == ':')) {
b = strtoul(t, &r, 16);
if (b > 255 || r == t)
break;
*p++ = (char)b;
++i;
t = r;
}
sdl->sdl_alen = i;
return 0;
}
static void
usage(void)
{
const char *progname;
progname = getprogname();
(void)fprintf(stderr, "Usage: %s [-n] hostname\n", progname);
(void)fprintf(stderr, " %s [-nv] -a\n", progname);
(void)fprintf(stderr, " %s [-v] -d [-a|hostname [proxy]]\n",
progname);
(void)fprintf(stderr, " %s -s hostname ether_addr [temp] [pub [proxy]]\n",
progname);
(void)fprintf(stderr, " %s -f filename\n", progname);
exit(1);
}
static struct rt_msghdr *
rtmsg(const int s, const int cmd, struct rt_msghdr *_rtm,
const struct sockaddr_inarp *sin, const struct sockaddr_dl *sdl)
{
static int seq;
struct rt_msghdr *rtm = _rtm;
char *cp;
int l;
static struct {
struct rt_msghdr m_rtm;
char m_space[512];
} m_rtmsg;
pid_t pid;
errno = 0;
if (rtm != NULL) {
memcpy(&m_rtmsg, rtm, rtm->rtm_msglen);
rtm = &m_rtmsg.m_rtm;
goto doit;
}
(void)memset(&m_rtmsg, 0, sizeof(m_rtmsg));
rtm = &m_rtmsg.m_rtm;
cp = m_rtmsg.m_space;
rtm->rtm_flags = flags;
rtm->rtm_version = RTM_VERSION;
switch (cmd) {
default:
errx(1, "internal wrong cmd");
/*NOTREACHED*/
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);
if (doing_proxy) {
if (!export_only) {
rtm->rtm_addrs |= RTA_NETMASK;
rtm->rtm_flags &= ~RTF_HOST;
}
}
rtm->rtm_addrs |= RTA_DST;
break;
case RTM_GET:
rtm->rtm_flags |= RTF_LLDATA;
rtm->rtm_addrs |= RTA_DST | RTA_GATEWAY;
}
#define NEXTADDR(w, s) \
if (rtm->rtm_addrs & (w)) { \
(void)memcpy(cp, &s, \
(size_t)((const struct sockaddr *)&s)->sa_len); \
RT_ADVANCE(cp, ((const struct sockaddr *)&s)); \
}
NEXTADDR(RTA_DST, *sin);
NEXTADDR(RTA_GATEWAY, *sdl);
NEXTADDR(RTA_NETMASK, so_mask);
rtm->rtm_msglen = cp - (char *)(void *)&m_rtmsg;
doit:
l = rtm->rtm_msglen;
rtm->rtm_seq = ++seq;
rtm->rtm_type = cmd;
if (prog_write(s, &m_rtmsg, (size_t)l) < 0) {
if (errno != ESRCH || cmd != RTM_DELETE) {
warn("writing to routing socket");
return NULL;
}
}
pid = prog_getpid();
do {
l = prog_read(s, &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;
}
static int
getinetaddr(const char *host, struct in_addr *inap)
{
struct hostent *hp;
if (inet_aton(host, inap) == 1)
return (0);
if ((hp = gethostbyname(host)) == NULL) {
warnx("%s: %s", host, hstrerror(h_errno));
return (-1);
}
(void)memcpy(inap, hp->h_addr, sizeof(*inap));
return (0);
}
static int
getifname(u_int16_t ifindex, char *ifname, size_t l)
{
int i;
struct ifaddrs *addr;
const struct sockaddr_dl *sdl;
static struct ifaddrs* ifaddrs = NULL;
if (ifaddrs == NULL) {
i = getifaddrs(&ifaddrs);
if (i != 0)
err(1, "getifaddrs");
}
for (addr = ifaddrs; addr; addr = addr->ifa_next) {
if (addr->ifa_addr == NULL ||
addr->ifa_addr->sa_family != AF_LINK)
continue;
sdl = (const struct sockaddr_dl *)(void *)addr->ifa_addr;
if (sdl && sdl->sdl_index == ifindex) {
(void) strlcpy(ifname, addr->ifa_name, l);
return 0;
}
}
return -1;
}
static int
getetheraddr(struct in_addr ipaddr, struct sockaddr_dl *sdl)
{
struct ifaddrs *ifaddrs, *addr;
in_addr_t ina, mask;
char ifname[IFNAMSIZ];
if (getifaddrs(&ifaddrs) != 0) {
warn("getifaddrs");
return -1;
}
for (addr = ifaddrs; addr; addr = addr->ifa_next) {
if (addr->ifa_addr == NULL ||
addr->ifa_addr->sa_family != AF_INET)
continue;
if ((addr->ifa_flags & (IFF_UP|IFF_BROADCAST|IFF_POINTOPOINT|
IFF_LOOPBACK|IFF_NOARP)) != (IFF_UP|IFF_BROADCAST))
continue;
mask = ((struct sockaddr_in *)(void *)addr->ifa_netmask)->sin_addr.s_addr;
ina = ((struct sockaddr_in *)(void *)addr->ifa_addr)->sin_addr.s_addr;
if ((ipaddr.s_addr & mask) != (ina & mask))
continue;
strlcpy(ifname, addr->ifa_name, sizeof(ifname));
break;
}
if (addr == NULL) {
warnx("No interface matched %s", inet_ntoa(ipaddr));
freeifaddrs(ifaddrs);
return -1;
}
for (addr = ifaddrs; addr; addr = addr->ifa_next) {
if (addr->ifa_addr == NULL ||
addr->ifa_addr->sa_family != AF_LINK)
continue;
if (strcmp(ifname, addr->ifa_name) != 0)
continue;
memcpy(sdl, addr->ifa_addr, sizeof(*sdl));
freeifaddrs(ifaddrs);
return 0;
}
warnx("No link address for interface %s", ifname);
freeifaddrs(ifaddrs);
return -1;
}
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