busybox/networking/arp.c
Samuel Thibault 77216c368f Fix non-Linux builds
Various tools are Linuxish and should thus only attempted to build on
Linux only. Some features are also Linux-only.

Also, libresolv is used on all GNU platforms, notably GNU/Hurd and
GNU/kfreeBSD.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
2022-11-29 14:10:22 +01:00

542 lines
12 KiB
C

/* vi: set sw=4 ts=4: */
/*
* arp.c - Manipulate the system ARP cache
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*
* Author: Fred N. van Kempen, <waltje at uwalt.nl.mugnet.org>
* Busybox port: Paul van Gool <pvangool at mimotech.com>
*
* modified for getopt32 by Arne Bernin <arne [at] alamut.de>
*/
//config:config ARP
//config: bool "arp (10 kb)"
//config: default y
//config: select PLATFORM_LINUX
//config: help
//config: Manipulate the system ARP cache.
//applet:IF_ARP(APPLET(arp, BB_DIR_SBIN, BB_SUID_DROP))
//kbuild:lib-$(CONFIG_ARP) += arp.o interface.o
//usage:#define arp_trivial_usage
//usage: "\n[-vn] [-H HWTYPE] [-i IF] -a [HOSTNAME]"
//usage: "\n[-v] [-i IF] -d HOSTNAME [pub]"
//usage: "\n[-v] [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [temp]"
//usage: "\n[-v] [-H HWTYPE] [-i IF] -s HOSTNAME HWADDR [netmask MASK] pub"
//usage: "\n[-v] [-H HWTYPE] [-i IF] -Ds HOSTNAME IFACE [netmask MASK] pub"
//usage:#define arp_full_usage "\n\n"
//usage: "Manipulate ARP cache\n"
//usage: "\n -a Display (all) hosts"
//usage: "\n -d Delete ARP entry"
//usage: "\n -s Set new entry"
//usage: "\n -v Verbose"
//usage: "\n -n Don't resolve names"
//usage: "\n -i IF Network interface"
//usage: "\n -D Read HWADDR from IFACE"
//usage: "\n -A,-p AF Protocol family"
//usage: "\n -H HWTYPE Hardware address type"
#include "libbb.h"
#include "common_bufsiz.h"
#include "inet_common.h"
#include <arpa/inet.h>
#include <net/if.h>
#include <net/if_arp.h>
#include <netinet/ether.h>
#include <netpacket/packet.h>
#define DEBUG 0
#define DFLT_AF "inet"
#define DFLT_HW "ether"
enum {
ARP_OPT_A = (1 << 0),
ARP_OPT_p = (1 << 1),
ARP_OPT_H = (1 << 2),
ARP_OPT_t = (1 << 3),
ARP_OPT_i = (1 << 4),
ARP_OPT_a = (1 << 5),
ARP_OPT_d = (1 << 6),
ARP_OPT_n = (1 << 7), /* do not resolve addresses */
ARP_OPT_D = (1 << 8), /* HW-address is devicename */
ARP_OPT_s = (1 << 9),
ARP_OPT_v = (1 << 10) * DEBUG, /* debugging output flag */
};
enum {
sockfd = 3, /* active socket descriptor */
};
struct globals {
const struct aftype *ap; /* current address family */
const struct hwtype *hw; /* current hardware type */
const char *device; /* current device */
smallint hw_set; /* flag if hw-type was set (-H) */
} FIX_ALIASING;
#define G (*(struct globals*)bb_common_bufsiz1)
#define ap (G.ap )
#define hw (G.hw )
#define device (G.device )
#define hw_set (G.hw_set )
#define INIT_G() do { \
setup_common_bufsiz(); \
device = ""; \
} while (0)
static const char options[] ALIGN1 =
"pub\0"
"priv\0"
"temp\0"
"trail\0"
"dontpub\0"
"auto\0"
"dev\0"
"netmask\0";
/* Delete an entry from the ARP cache. */
/* Called only from main, once */
static int arp_del(char **args)
{
char *host;
struct arpreq req;
struct sockaddr sa;
int flags = 0;
int err;
memset(&req, 0, sizeof(req));
/* Resolve the host name. */
host = *args;
if (ap->input(host, &sa) < 0) {
bb_simple_herror_msg_and_die(host);
}
/* If a host has more than one address, use the correct one! */
memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));
if (hw_set)
req.arp_ha.sa_family = hw->type;
req.arp_flags = ATF_PERM;
args++;
while (*args != NULL) {
switch (index_in_strings(options, *args)) {
case 0: /* "pub" */
flags |= 1;
args++;
break;
case 1: /* "priv" */
flags |= 2;
args++;
break;
case 2: /* "temp" */
req.arp_flags &= ~ATF_PERM;
args++;
break;
case 3: /* "trail" */
req.arp_flags |= ATF_USETRAILERS;
args++;
break;
case 4: /* "dontpub" */
#ifdef HAVE_ATF_DONTPUB
req.arp_flags |= ATF_DONTPUB;
#else
bb_simple_error_msg("feature ATF_DONTPUB is not supported");
#endif
args++;
break;
case 5: /* "auto" */
#ifdef HAVE_ATF_MAGIC
req.arp_flags |= ATF_MAGIC;
#else
bb_simple_error_msg("feature ATF_MAGIC is not supported");
#endif
args++;
break;
case 6: /* "dev" */
if (*++args == NULL)
bb_show_usage();
device = *args;
args++;
break;
case 7: /* "netmask" */
if (*++args == NULL)
bb_show_usage();
if (strcmp(*args, "255.255.255.255") != 0) {
host = *args;
if (ap->input(host, &sa) < 0) {
bb_simple_herror_msg_and_die(host);
}
memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
req.arp_flags |= ATF_NETMASK;
}
args++;
break;
default:
bb_show_usage();
break;
}
}
if (flags == 0)
flags = 3;
strncpy_IFNAMSIZ(req.arp_dev, device);
err = -1;
/* Call the kernel. */
if (flags & 2) {
if (option_mask32 & ARP_OPT_v)
bb_simple_error_msg("SIOCDARP(nopub)");
err = ioctl(sockfd, SIOCDARP, &req);
if (err < 0) {
if (errno == ENXIO) {
if (flags & 1)
goto nopub;
printf("No ARP entry for %s\n", host);
return -1;
}
bb_simple_perror_msg_and_die("SIOCDARP(priv)");
}
}
if ((flags & 1) && err) {
nopub:
req.arp_flags |= ATF_PUBL;
if (option_mask32 & ARP_OPT_v)
bb_simple_error_msg("SIOCDARP(pub)");
if (ioctl(sockfd, SIOCDARP, &req) < 0) {
if (errno == ENXIO) {
printf("No ARP entry for %s\n", host);
return -1;
}
bb_simple_perror_msg_and_die("SIOCDARP(pub)");
}
}
return 0;
}
/* Get the hardware address to a specified interface name */
static void arp_getdevhw(char *ifname, struct sockaddr *sa)
{
struct ifreq ifr;
const struct hwtype *xhw;
strncpy_IFNAMSIZ(ifr.ifr_name, ifname);
ioctl_or_perror_and_die(sockfd, SIOCGIFHWADDR, &ifr,
"can't get HW-Address for '%s'", ifname);
if (hw_set && (ifr.ifr_hwaddr.sa_family != hw->type)) {
bb_simple_error_msg_and_die("protocol type mismatch");
}
memcpy(sa, &(ifr.ifr_hwaddr), sizeof(struct sockaddr));
if (option_mask32 & ARP_OPT_v) {
xhw = get_hwntype(ifr.ifr_hwaddr.sa_family);
if (!xhw || !xhw->print) {
xhw = get_hwntype(-1);
}
bb_error_msg("device '%s' has HW address %s '%s'",
ifname, xhw->name,
xhw->print((unsigned char *) &ifr.ifr_hwaddr.sa_data));
}
}
/* Set an entry in the ARP cache. */
/* Called only from main, once */
static int arp_set(char **args)
{
char *host;
struct arpreq req;
struct sockaddr sa;
int flags;
memset(&req, 0, sizeof(req));
host = *args++;
if (ap->input(host, &sa) < 0) {
bb_simple_herror_msg_and_die(host);
}
/* If a host has more than one address, use the correct one! */
memcpy(&req.arp_pa, &sa, sizeof(struct sockaddr));
/* Fetch the hardware address. */
if (*args == NULL) {
bb_simple_error_msg_and_die("need hardware address");
}
if (option_mask32 & ARP_OPT_D) {
arp_getdevhw(*args++, &req.arp_ha);
} else {
if (hw->input(*args++, &req.arp_ha) < 0) {
bb_simple_error_msg_and_die("invalid hardware address");
}
}
/* Check out any modifiers. */
flags = ATF_PERM | ATF_COM;
while (*args != NULL) {
switch (index_in_strings(options, *args)) {
case 0: /* "pub" */
flags |= ATF_PUBL;
args++;
break;
case 1: /* "priv" */
flags &= ~ATF_PUBL;
args++;
break;
case 2: /* "temp" */
flags &= ~ATF_PERM;
args++;
break;
case 3: /* "trail" */
flags |= ATF_USETRAILERS;
args++;
break;
case 4: /* "dontpub" */
#ifdef HAVE_ATF_DONTPUB
flags |= ATF_DONTPUB;
#else
bb_simple_error_msg("feature ATF_DONTPUB is not supported");
#endif
args++;
break;
case 5: /* "auto" */
#ifdef HAVE_ATF_MAGIC
flags |= ATF_MAGIC;
#else
bb_simple_error_msg("feature ATF_MAGIC is not supported");
#endif
args++;
break;
case 6: /* "dev" */
if (*++args == NULL)
bb_show_usage();
device = *args;
args++;
break;
case 7: /* "netmask" */
if (*++args == NULL)
bb_show_usage();
if (strcmp(*args, "255.255.255.255") != 0) {
host = *args;
if (ap->input(host, &sa) < 0) {
bb_simple_herror_msg_and_die(host);
}
memcpy(&req.arp_netmask, &sa, sizeof(struct sockaddr));
flags |= ATF_NETMASK;
}
args++;
break;
default:
bb_show_usage();
break;
}
}
/* Fill in the remainder of the request. */
req.arp_flags = flags;
strncpy_IFNAMSIZ(req.arp_dev, device);
/* Call the kernel. */
if (option_mask32 & ARP_OPT_v)
bb_simple_error_msg("SIOCSARP()");
xioctl(sockfd, SIOCSARP, &req);
return 0;
}
/* Print the contents of an ARP request block. */
static void
arp_disp(const char *name, char *ip, int type, int arp_flags,
char *hwa, char *mask, char *dev)
{
static const int arp_masks[] = {
ATF_PERM, ATF_PUBL,
#ifdef HAVE_ATF_MAGIC
ATF_MAGIC,
#endif
#ifdef HAVE_ATF_DONTPUB
ATF_DONTPUB,
#endif
ATF_USETRAILERS,
};
static const char arp_labels[] ALIGN1 = "PERM\0""PUP\0"
#ifdef HAVE_ATF_MAGIC
"AUTO\0"
#endif
#ifdef HAVE_ATF_DONTPUB
"DONTPUB\0"
#endif
"TRAIL\0"
;
const struct hwtype *xhw;
xhw = get_hwntype(type);
if (xhw == NULL)
xhw = get_hwtype(DFLT_HW);
printf("%s (%s) at ", name, ip);
if (!(arp_flags & ATF_COM)) {
if (arp_flags & ATF_PUBL)
printf("* ");
else
printf("<incomplete> ");
} else {
printf("%s [%s] ", hwa, xhw->name);
}
if (arp_flags & ATF_NETMASK)
printf("netmask %s ", mask);
print_flags_separated(arp_masks, arp_labels, arp_flags, " ");
printf(" on %s\n", dev);
}
/* Display the contents of the ARP cache in the kernel. */
/* Called only from main, once */
static int arp_show(char *name)
{
const char *host;
const char *hostname;
FILE *fp;
struct sockaddr sa;
int type, flags;
int num;
unsigned entries = 0, shown = 0;
char ip[128];
char hwa[128];
char mask[128];
char line[128];
char dev[128];
host = NULL;
if (name != NULL) {
/* Resolve the host name. */
if (ap->input(name, &sa) < 0) {
bb_simple_herror_msg_and_die(name);
}
host = xstrdup(ap->sprint(&sa, 1));
}
fp = xfopen_for_read("/proc/net/arp");
/* Bypass header -- read one line */
fgets(line, sizeof(line), fp);
/* Read the ARP cache entries. */
while (fgets(line, sizeof(line), fp)) {
mask[0] = '-'; mask[1] = '\0';
dev[0] = '-'; dev[1] = '\0';
/* All these strings can't overflow
* because fgets above reads limited amount of data */
num = sscanf(line, "%s 0x%x 0x%x %s %s %s\n",
ip, &type, &flags, hwa, mask, dev);
if (num < 4)
break;
entries++;
/* if the user specified hw-type differs, skip it */
if (hw_set && (type != hw->type))
continue;
/* if the user specified address differs, skip it */
if (host && strcmp(ip, host) != 0)
continue;
/* if the user specified device differs, skip it */
if (device[0] && strcmp(dev, device) != 0)
continue;
shown++;
/* This IS ugly but it works -be */
hostname = "?";
if (!(option_mask32 & ARP_OPT_n)) {
if (ap->input(ip, &sa) < 0)
hostname = ip;
else
hostname = ap->sprint(&sa, (option_mask32 & ARP_OPT_n) | 0x8000);
if (strcmp(hostname, ip) == 0)
hostname = "?";
}
arp_disp(hostname, ip, type, flags, hwa, mask, dev);
}
if (option_mask32 & ARP_OPT_v)
printf("Entries: %u\tSkipped: %u\tFound: %u\n",
entries, entries - shown, shown);
if (!shown) {
if (hw_set || host || device[0])
printf("No match found in %u entries\n", entries);
}
if (ENABLE_FEATURE_CLEAN_UP) {
free((char*)host);
fclose(fp);
}
return 0;
}
int arp_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int arp_main(int argc UNUSED_PARAM, char **argv)
{
const char *hw_type;
const char *protocol;
unsigned opts;
INIT_G();
xmove_fd(xsocket(AF_INET, SOCK_DGRAM, 0), sockfd);
ap = get_aftype(DFLT_AF);
/* Defaults are always supported */
//if (!ap)
// bb_error_msg_and_die("%s: %s not supported", DFLT_AF, "address family");
hw = get_hwtype(DFLT_HW);
//if (!hw)
// bb_error_msg_and_die("%s: %s not supported", DFLT_HW, "hardware type");
opts = getopt32(argv, "A:p:H:t:i:adnDsv", &protocol, &protocol,
&hw_type, &hw_type, &device);
argv += optind;
if (opts & (ARP_OPT_A | ARP_OPT_p)) {
ap = get_aftype(protocol);
if (!ap)
bb_error_msg_and_die("%s: unknown %s", protocol, "address family");
}
if (opts & (ARP_OPT_H | ARP_OPT_t)) {
hw = get_hwtype(hw_type);
if (!hw)
bb_error_msg_and_die("%s: unknown %s", hw_type, "hardware type");
hw_set = 1;
}
//if (opts & ARP_OPT_i)... -i
if (ap->af != AF_INET) {
bb_error_msg_and_die("%s: kernel only supports 'inet'", ap->name);
}
if (hw->alen <= 0) {
bb_error_msg_and_die("%s: %s without ARP support",
hw->name, "hardware type");
}
/* Now see what we have to do here... */
if (opts & (ARP_OPT_d | ARP_OPT_s)) {
if (argv[0] == NULL)
bb_simple_error_msg_and_die("need host name");
if (opts & ARP_OPT_s)
return arp_set(argv);
return arp_del(argv);
}
//if (opts & ARP_OPT_a) - default
return arp_show(argv[0]);
}