freebsd-dev/usr.sbin/arp/arp.c
2003-01-17 08:10:43 +00:00

767 lines
18 KiB
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.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 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.
*/
#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
#if 0
static char const sccsid[] = "@(#)from: arp.c 8.2 (Berkeley) 1/2/94";
#endif
static const char rcsid[] =
"$FreeBSD$";
#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/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>
void search(u_long addr, void (*action)(struct sockaddr_dl *sdl,
struct sockaddr_inarp *sin, struct rt_msghdr *rtm));
void print_entry(struct sockaddr_dl *sdl,
struct sockaddr_inarp *addr, struct rt_msghdr *rtm);
void nuke_entry(struct sockaddr_dl *sdl,
struct sockaddr_inarp *addr, struct rt_msghdr *rtm);
int delete(char *host, char *info);
void usage(void);
int set(int argc, char **argv);
int get(char *host);
int file(char *name);
void getsocket(void);
int my_ether_aton(char *a, struct ether_addr *n);
int rtmsg(int cmd);
int get_ether_addr(u_int32_t ipaddr, struct ether_addr *hwaddr);
static pid_t pid;
static int nflag; /* no reverse dns lookups */
static int aflag; /* do it for all entries */
static int s = -1;
struct sockaddr_in so_mask;
struct sockaddr_inarp blank_sin, sin_m;
struct sockaddr_dl blank_sdl, sdl_m;
int expire_time, flags, doing_proxy, proxy_only, found_entry;
struct {
struct rt_msghdr m_rtm;
char m_space[512];
} m_rtmsg;
/* 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 ROUNDUP(a) \
((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
#define SETFUNC(f) { if (func) usage(); func = (f); }
int
main(int argc, char *argv[])
{
int ch, func = 0;
int rtn = 0;
pid = getpid();
while ((ch = getopt(argc, argv, "andfsS")) != -1)
switch((char)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 '?':
default:
usage();
}
argc -= optind;
argv += optind;
bzero(&so_mask, sizeof(so_mask));
so_mask.sin_len = 8;
so_mask.sin_addr.s_addr = 0xffffffff;
bzero(&blank_sin, sizeof(blank_sin));
blank_sin.sin_len = sizeof(blank_sin);
blank_sin.sin_family = AF_INET;
bzero(&blank_sdl, sizeof(blank_sdl));
blank_sdl.sdl_len = sizeof(blank_sdl);
blank_sdl.sdl_family = AF_LINK;
if (!func)
func = F_GET;
switch (func) {
case F_GET:
if (aflag) {
if (argc != 0)
usage();
search(0, print_entry);
} else {
if (argc != 1)
usage();
get(argv[0]);
}
break;
case F_SET:
case F_REPLACE:
if (argc < 2 || argc > 6)
usage();
if (func == F_REPLACE)
(void) delete(argv[0], NULL);
rtn = set(argc, argv) ? 1 : 0;
break;
case F_DELETE:
if (aflag) {
if (argc != 0)
usage();
search(0, nuke_entry);
} else {
if (argc < 1 || argc > 2)
usage();
rtn = delete(argv[0], argv[1]);
}
break;
case F_FILESET:
if (argc != 1)
usage();
rtn = file(argv[0]);
break;
}
return(rtn);
}
/*
* Process a file to set standard arp entries
*/
int
file(char *name)
{
FILE *fp;
int i, retval;
char line[100], arg[5][50], *args[5], *p;
if ((fp = fopen(name, "r")) == NULL)
errx(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, 100, fp) != NULL) {
if ((p = strchr(line, '#')) != NULL)
*p = '\0';
for (p = line; isblank(*p); p++);
if (*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);
}
void
getsocket(void)
{
if (s < 0) {
s = socket(PF_ROUTE, SOCK_RAW, 0);
if (s < 0)
err(1, "socket");
}
}
/*
* Set an individual arp entry
*/
int
set(int argc, char **argv)
{
struct hostent *hp;
register struct sockaddr_inarp *addr = &sin_m;
register struct sockaddr_dl *sdl;
register struct rt_msghdr *rtm = &(m_rtmsg.m_rtm);
struct ether_addr *ea;
char *host = argv[0], *eaddr = argv[1];
getsocket();
argc -= 2;
argv += 2;
sdl_m = blank_sdl;
sin_m = blank_sin;
addr->sin_addr.s_addr = inet_addr(host);
if (addr->sin_addr.s_addr == INADDR_NONE) {
if (!(hp = gethostbyname(host))) {
warnx("%s: %s", host, hstrerror(h_errno));
return (1);
}
bcopy((char *)hp->h_addr, (char *)&addr->sin_addr,
sizeof addr->sin_addr);
}
doing_proxy = flags = proxy_only = expire_time = 0;
while (argc-- > 0) {
if (strncmp(argv[0], "temp", 4) == 0) {
struct timeval tv;
gettimeofday(&tv, 0);
expire_time = tv.tv_sec + 20 * 60;
}
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;
sin_m.sin_other = SIN_PROXY;
argc--; argv++;
}
} else if (strncmp(argv[0], "trail", 5) == 0) {
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(addr->sin_addr.s_addr, ea)) {
printf("no interface found for %s\n",
inet_ntoa(addr->sin_addr));
return (1);
}
sdl_m.sdl_alen = ETHER_ADDR_LEN;
} else {
if (my_ether_aton(eaddr, ea) == 0)
sdl_m.sdl_alen = ETHER_ADDR_LEN;
}
tryagain:
if (rtmsg(RTM_GET) < 0) {
warn("%s", host);
return (1);
}
addr = (struct sockaddr_inarp *)(rtm + 1);
sdl = (struct sockaddr_dl *)(ROUNDUP(addr->sin_len) + (char *)addr);
if (addr->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
if (sdl->sdl_family == AF_LINK &&
(rtm->rtm_flags & RTF_LLINFO) &&
!(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
case IFT_ISO88024: case IFT_ISO88025: case IFT_L2VLAN:
goto overwrite;
}
if (doing_proxy == 0) {
printf("set: can only proxy for %s\n", host);
return (1);
}
if (sin_m.sin_other & SIN_PROXY) {
printf("set: proxy entry exists for non 802 device\n");
return(1);
}
sin_m.sin_other = SIN_PROXY;
proxy_only = 1;
goto tryagain;
}
overwrite:
if (sdl->sdl_family != AF_LINK) {
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));
}
/*
* Display an individual arp entry
*/
int
get(char *host)
{
struct hostent *hp;
struct sockaddr_inarp *addr = &sin_m;
sin_m = blank_sin;
addr->sin_addr.s_addr = inet_addr(host);
if (addr->sin_addr.s_addr == INADDR_NONE) {
if (!(hp = gethostbyname(host)))
errx(1, "%s: %s", host, hstrerror(h_errno));
bcopy((char *)hp->h_addr, (char *)&addr->sin_addr,
sizeof addr->sin_addr);
}
search(addr->sin_addr.s_addr, print_entry);
if (found_entry == 0) {
printf("%s (%s) -- no entry\n",
host, inet_ntoa(addr->sin_addr));
return(1);
}
return(0);
}
/*
* Delete an arp entry
*/
int
delete(char *host, char *info)
{
struct hostent *hp;
register struct sockaddr_inarp *addr = &sin_m;
register struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
struct sockaddr_dl *sdl;
getsocket();
sin_m = blank_sin;
if (info) {
if (strncmp(info, "pub", 3) == 0)
sin_m.sin_other = SIN_PROXY;
else
usage();
}
addr->sin_addr.s_addr = inet_addr(host);
if (addr->sin_addr.s_addr == INADDR_NONE) {
if (!(hp = gethostbyname(host))) {
warnx("%s: %s", host, hstrerror(h_errno));
return (1);
}
bcopy((char *)hp->h_addr, (char *)&addr->sin_addr,
sizeof addr->sin_addr);
}
tryagain:
if (rtmsg(RTM_GET) < 0) {
warn("%s", host);
return (1);
}
addr = (struct sockaddr_inarp *)(rtm + 1);
sdl = (struct sockaddr_dl *)(ROUNDUP(addr->sin_len) + (char *)addr);
if (addr->sin_addr.s_addr == sin_m.sin_addr.s_addr) {
if (sdl->sdl_family == AF_LINK &&
(rtm->rtm_flags & RTF_LLINFO) &&
!(rtm->rtm_flags & RTF_GATEWAY)) switch (sdl->sdl_type) {
case IFT_ETHER: case IFT_FDDI: case IFT_ISO88023:
case IFT_ISO88024: case IFT_ISO88025: case IFT_L2VLAN:
goto delete;
}
}
if (sin_m.sin_other & SIN_PROXY) {
fprintf(stderr, "delete: can't locate %s\n",host);
return (1);
} else {
sin_m.sin_other = SIN_PROXY;
goto tryagain;
}
delete:
if (sdl->sdl_family != AF_LINK) {
printf("cannot locate %s\n", host);
return (1);
}
if (rtmsg(RTM_DELETE) == 0) {
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
*/
void
search(u_long addr, void (*action)(struct sockaddr_dl *sdl,
struct sockaddr_inarp *sin, struct rt_msghdr *rtm))
{
int mib[6];
size_t needed;
char *lim, *buf, *next;
struct rt_msghdr *rtm;
struct sockaddr_inarp *sin2;
struct sockaddr_dl *sdl;
mib[0] = CTL_NET;
mib[1] = PF_ROUTE;
mib[2] = 0;
mib[3] = AF_INET;
mib[4] = NET_RT_FLAGS;
mib[5] = RTF_LLINFO;
if (sysctl(mib, 6, NULL, &needed, NULL, 0) < 0)
errx(1, "route-sysctl-estimate");
if ((buf = malloc(needed)) == NULL)
errx(1, "malloc");
if (sysctl(mib, 6, buf, &needed, NULL, 0) < 0)
errx(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);
(char *)sdl = (char *)sin2 + ROUNDUP(sin2->sin_len);
if (addr) {
if (addr != sin2->sin_addr.s_addr)
continue;
found_entry = 1;
}
(*action)(sdl, sin2, rtm);
}
free(buf);
}
/*
* Display an arp entry
*/
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;
char ifname[IF_NAMESIZE];
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)
printf("%s", ether_ntoa((struct ether_addr *)LLADDR(sdl)));
else
printf("(incomplete)");
if (if_indextoname(sdl->sdl_index, ifname) != NULL)
printf(" on %s", ifname);
if (rtm->rtm_rmx.rmx_expire == 0)
printf(" permanent");
if (addr->sin_other & SIN_PROXY)
printf(" published (proxy only)");
if (rtm->rtm_addrs & RTA_NETMASK) {
addr = (struct sockaddr_inarp *)
(ROUNDUP(sdl->sdl_len) + (char *)sdl);
if (addr->sin_addr.s_addr == 0xffffffff)
printf(" published");
if (addr->sin_len != 8)
printf("(weird)");
}
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;
default:
break;
}
printf("\n");
}
/*
* Nuke an arp entry
*/
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));
delete(ip, NULL);
}
int
my_ether_aton(char *a, struct ether_addr *n)
{
struct ether_addr *ea;
if ((ea = ether_aton(a)) == NULL) {
warnx("invalid Ethernet address '%s'", a);
return (1);
}
*n = *ea;
return (0);
}
void
usage(void)
{
fprintf(stderr, "%s\n%s\n%s\n%s\n%s\n%s\n%s\n",
"usage: arp [-n] hostname",
" arp [-n] -a",
" arp -d hostname [pub]",
" arp -d -a",
" arp -s hostname ether_addr [temp] [pub]",
" arp -S hostname ether_addr [temp] [pub]",
" arp -f filename");
exit(1);
}
int
rtmsg(int cmd)
{
static int seq;
int rlen;
register struct rt_msghdr *rtm = &m_rtmsg.m_rtm;
register char *cp = m_rtmsg.m_space;
register int l;
errno = 0;
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);
sin_m.sin_other = 0;
if (doing_proxy) {
if (proxy_only)
sin_m.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) \
if (rtm->rtm_addrs & (w)) { \
bcopy((char *)&s, cp, sizeof(s)); cp += ROUNDUP(sizeof(s));}
NEXTADDR(RTA_DST, sin_m);
NEXTADDR(RTA_GATEWAY, sdl_m);
NEXTADDR(RTA_NETMASK, so_mask);
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 (-1);
}
}
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 (0);
}
/*
* 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(u_int32_t ipaddr, struct ether_addr *hwaddr)
{
struct ifreq *ifr, *ifend, *ifp;
u_int32_t ina, mask;
struct sockaddr_dl *dla;
struct ifreq ifreq;
struct ifconf ifc;
struct ifreq ifs[MAX_IFS];
int sock;
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)");
close(sock);
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));
/*
* 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))
goto nextif;
/*
* 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;
if ((ipaddr & mask) != (ina & mask))
goto nextif;
break;
}
nextif:
ifr = (struct ifreq *) ((char *)&ifr->ifr_addr
+ MAX(ifr->ifr_addr.sa_len, sizeof(ifr->ifr_addr)));
}
if (ifr >= ifend) {
close(sock);
return 0;
}
/*
* 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;
memcpy(hwaddr, LLADDR(dla), dla->sdl_alen);
close (sock);
printf("using interface %s for proxy with address ",
ifp->ifr_name);
printf("%s\n", ether_ntoa(hwaddr));
return dla->sdl_alen;
}
ifr = (struct ifreq *) ((char *)&ifr->ifr_addr
+ MAX(ifr->ifr_addr.sa_len, sizeof(ifr->ifr_addr)));
}
return 0;
}