release/src/router/busybox/networking/arping.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   4  *
   5  * Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
   6  * Busybox port: Nick Fedchik <nick@fedchik.org.ua>
   7  */
   8
   9 //usage:#define arping_trivial_usage
  10 //usage:       "[-fqbDUA] [-c CNT] [-w TIMEOUT] [-I IFACE] [-s SRC_IP] DST_IP"
  11 //usage:#define arping_full_usage "\n\n"
  12 //usage:       "Send ARP requests/replies\n"
  13 //usage:     "\n        -f              Quit on first ARP reply"
  14 //usage:     "\n        -q              Quiet"
  15 //usage:     "\n        -b              Keep broadcasting, don't go unicast"
  16 //usage:     "\n        -D              Exit with 1 if DST_IP replies"
  17 //usage:     "\n        -U              Unsolicited ARP mode, update your neighbors"
  18 //usage:     "\n        -A              ARP answer mode, update your neighbors"
  19 //usage:     "\n        -c N            Stop after sending N ARP requests"
  20 //usage:     "\n        -w TIMEOUT      Seconds to wait for ARP reply"
  21 //usage:     "\n        -I IFACE        Interface to use (default eth0)"
  22 //usage:     "\n        -s SRC_IP       Sender IP address"
  23 //usage:     "\n        DST_IP          Target IP address"
  24
  25 #include <arpa/inet.h>
  26 #include <net/if.h>
  27 #include <netinet/ether.h>
  28 #include <netpacket/packet.h>
  29
  30 #include "libbb.h"
  31 #include "common_bufsiz.h"
  32
  33 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
  34 #define MONOTONIC_US() ((unsigned)monotonic_us())
  35
  36 enum {
  37         DAD = 1,
  38         UNSOLICITED = 2,
  39         ADVERT = 4,
  40         QUIET = 8,
  41         QUIT_ON_REPLY = 16,
  42         BCAST_ONLY = 32,
  43         UNICASTING = 64
  44 };
  45
  46 struct globals {
  47         struct in_addr src;
  48         struct in_addr dst;
  49         struct sockaddr_ll me;
  50         struct sockaddr_ll he;
  51         int sock_fd;
  52
  53         int count; // = -1;
  54         unsigned last;
  55         unsigned timeout_us;
  56         unsigned start;
  57
  58         unsigned sent;
  59         unsigned brd_sent;
  60         unsigned received;
  61         unsigned brd_recv;
  62         unsigned req_recv;
  63 } FIX_ALIASING;
  64 #define G (*(struct globals*)bb_common_bufsiz1)
  65 #define src        (G.src       )
  66 #define dst        (G.dst       )
  67 #define me         (G.me        )
  68 #define he         (G.he        )
  69 #define sock_fd    (G.sock_fd   )
  70 #define count      (G.count     )
  71 #define last       (G.last      )
  72 #define timeout_us (G.timeout_us)
  73 #define start      (G.start     )
  74 #define sent       (G.sent      )
  75 #define brd_sent   (G.brd_sent  )
  76 #define received   (G.received  )
  77 #define brd_recv   (G.brd_recv  )
  78 #define req_recv   (G.req_recv  )
  79 #define INIT_G() do { \
  80         setup_common_bufsiz(); \
  81         count = -1; \
  82 } while (0)
  83
  84 // If GNUisms are not available...
  85 //static void *mempcpy(void *_dst, const void *_src, int n)
  86 //{
  87 //      memcpy(_dst, _src, n);
  88 //      return (char*)_dst + n;
  89 //}
  90
  91 static int send_pack(struct in_addr *src_addr,
  92                         struct in_addr *dst_addr, struct sockaddr_ll *ME,
  93                         struct sockaddr_ll *HE)
  94 {
  95         int err;
  96         unsigned char buf[256];
  97         struct arphdr *ah = (struct arphdr *) buf;
  98         unsigned char *p = (unsigned char *) (ah + 1);
  99
 100         ah->ar_hrd = htons(ARPHRD_ETHER);
 101         ah->ar_pro = htons(ETH_P_IP);
 102         ah->ar_hln = ME->sll_halen;
 103         ah->ar_pln = 4;
 104         ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
 105
 106         p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
 107         p = mempcpy(p, src_addr, 4);
 108
 109         if (option_mask32 & ADVERT)
 110                 p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
 111         else
 112                 p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
 113
 114         p = mempcpy(p, dst_addr, 4);
 115
 116         err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
 117         if (err == p - buf) {
 118                 last = MONOTONIC_US();
 119                 sent++;
 120                 if (!(option_mask32 & UNICASTING))
 121                         brd_sent++;
 122         }
 123         return err;
 124 }
 125
 126 static void finish(void) NORETURN;
 127 static void finish(void)
 128 {
 129         if (!(option_mask32 & QUIET)) {
 130                 printf("Sent %u probe(s) (%u broadcast(s))\n"
 131                         "Received %u repl%s"
 132                         " (%u request(s), %u broadcast(s))\n",
 133                         sent, brd_sent,
 134                         received, (received == 1) ? "ies" : "y",
 135                         req_recv, brd_recv);
 136         }
 137         if (option_mask32 & DAD)
 138                 exit(!!received);
 139         if (option_mask32 & UNSOLICITED)
 140                 exit(EXIT_SUCCESS);
 141         exit(!received);
 142 }
 143
 144 static void catcher(void)
 145 {
 146         unsigned now;
 147
 148         now = MONOTONIC_US();
 149         if (start == 0)
 150                 start = now;
 151
 152         if (count == 0 || (timeout_us && (now - start) > timeout_us))
 153                 finish();
 154
 155         /* count < 0 means "infinite count" */
 156         if (count > 0)
 157                 count--;
 158
 159         if (last == 0 || (now - last) > 500000) {
 160                 send_pack(&src, &dst, &me, &he);
 161                 if (count == 0 && (option_mask32 & UNSOLICITED))
 162                         finish();
 163         }
 164         alarm(1);
 165 }
 166
 167 static void recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
 168 {
 169         struct arphdr *ah = (struct arphdr *) buf;
 170         unsigned char *p = (unsigned char *) (ah + 1);
 171         struct in_addr src_ip, dst_ip;
 172         /* moves below assume in_addr is 4 bytes big, ensure that */
 173         struct BUG_in_addr_must_be_4 {
 174                 char BUG_in_addr_must_be_4[
 175                         sizeof(struct in_addr) == 4 ? 1 : -1
 176                 ];
 177                 char BUG_s_addr_must_be_4[
 178                         sizeof(src_ip.s_addr) == 4 ? 1 : -1
 179                 ];
 180         };
 181
 182         /* Filter out wild packets */
 183         if (FROM->sll_pkttype != PACKET_HOST
 184          && FROM->sll_pkttype != PACKET_BROADCAST
 185          && FROM->sll_pkttype != PACKET_MULTICAST)
 186                 return;
 187
 188         /* Only these types are recognized */
 189         if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
 190                 return;
 191
 192         /* ARPHRD check and this darned FDDI hack here :-( */
 193         if (ah->ar_hrd != htons(FROM->sll_hatype)
 194          && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
 195                 return;
 196
 197         /* Protocol must be IP. */
 198         if (ah->ar_pro != htons(ETH_P_IP)
 199          || (ah->ar_pln != 4)
 200          || (ah->ar_hln != me.sll_halen)
 201          || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
 202                 return;
 203
 204         move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
 205         move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
 206
 207         if (dst.s_addr != src_ip.s_addr)
 208                 return;
 209         if (!(option_mask32 & DAD)) {
 210                 if ((src.s_addr != dst_ip.s_addr)
 211                  || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
 212                         return;
 213         } else {
 214                 /* DAD packet was:
 215                    src_ip = 0 (or some src)
 216                    src_hw = ME
 217                    dst_ip = tested address
 218                    dst_hw = <unspec>
 219
 220                    We fail, if receive request/reply with:
 221                    src_ip = tested_address
 222                    src_hw != ME
 223                    if src_ip in request was not zero, check
 224                    also that it matches to dst_ip, otherwise
 225                    dst_ip/dst_hw do not matter.
 226                  */
 227                 if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
 228                  || (src.s_addr && src.s_addr != dst_ip.s_addr))
 229                         return;
 230         }
 231         if (!(option_mask32 & QUIET)) {
 232                 int s_printed = 0;
 233
 234                 printf("%scast re%s from %s [%02x:%02x:%02x:%02x:%02x:%02x]",
 235                         FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
 236                         ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
 237                         inet_ntoa(src_ip),
 238                         p[0], p[1], p[2], p[3], p[4], p[5]
 239                 );
 240                 if (dst_ip.s_addr != src.s_addr) {
 241                         printf("for %s ", inet_ntoa(dst_ip));
 242                         s_printed = 1;
 243                 }
 244                 if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
 245                         unsigned char *pp = p + ah->ar_hln + 4;
 246                         if (!s_printed)
 247                                 printf("for ");
 248                         printf("[%02x:%02x:%02x:%02x:%02x:%02x]",
 249                                 pp[0], pp[1], pp[2], pp[3], pp[4], pp[5]
 250                         );
 251                 }
 252
 253                 if (last) {
 254                         unsigned diff = MONOTONIC_US() - last;
 255                         printf(" %u.%03ums\n", diff / 1000, diff % 1000);
 256                 } else {
 257                         puts(" UNSOLICITED?");
 258                 }
 259                 fflush_all();
 260         }
 261         received++;
 262         if (FROM->sll_pkttype != PACKET_HOST)
 263                 brd_recv++;
 264         if (ah->ar_op == htons(ARPOP_REQUEST))
 265                 req_recv++;
 266         if (option_mask32 & QUIT_ON_REPLY)
 267                 finish();
 268         if (!(option_mask32 & BCAST_ONLY)) {
 269                 memcpy(he.sll_addr, p, me.sll_halen);
 270                 option_mask32 |= UNICASTING;
 271         }
 272 }
 273
 274 int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 275 int arping_main(int argc UNUSED_PARAM, char **argv)
 276 {
 277         const char *device = "eth0";
 278         char *source = NULL;
 279         char *target;
 280         unsigned char *packet;
 281         char *err_str;
 282
 283         INIT_G();
 284
 285         sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0);
 286
 287         // Drop suid root privileges
 288         // Need to remove SUID_NEVER from applets.h for this to work
 289         //xsetuid(getuid());
 290
 291         {
 292                 unsigned opt;
 293                 char *str_timeout;
 294
 295                 /* Dad also sets quit_on_reply.
 296                  * Advert also sets unsolicited.
 297                  */
 298                 opt_complementary = "=1:Df:AU:c+";
 299                 opt = getopt32(argv, "DUAqfbc:w:I:s:",
 300                                 &count, &str_timeout, &device, &source);
 301                 if (opt & 0x80) /* -w: timeout */
 302                         timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
 303                 //if (opt & 0x200) /* -s: source */
 304                 option_mask32 &= 0x3f; /* set respective flags */
 305         }
 306
 307         target = argv[optind];
 308         err_str = xasprintf("interface %s %%s", device);
 309         xfunc_error_retval = 2;
 310
 311         {
 312                 struct ifreq ifr;
 313
 314                 memset(&ifr, 0, sizeof(ifr));
 315                 strncpy_IFNAMSIZ(ifr.ifr_name, device);
 316                 /* We use ifr.ifr_name in error msg so that problem
 317                  * with truncated name will be visible */
 318                 ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found");
 319                 me.sll_ifindex = ifr.ifr_ifindex;
 320
 321                 xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr);
 322
 323                 if (!(ifr.ifr_flags & IFF_UP)) {
 324                         bb_error_msg_and_die(err_str, "is down");
 325                 }
 326                 if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
 327                         bb_error_msg(err_str, "is not ARPable");
 328                         return (option_mask32 & DAD ? 0 : 2);
 329                 }
 330         }
 331
 332         /* if (!inet_aton(target, &dst)) - not needed */ {
 333                 len_and_sockaddr *lsa;
 334                 lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
 335                 dst = lsa->u.sin.sin_addr;
 336                 if (ENABLE_FEATURE_CLEAN_UP)
 337                         free(lsa);
 338         }
 339
 340         if (source && !inet_aton(source, &src)) {
 341                 bb_error_msg_and_die("invalid source address %s", source);
 342         }
 343
 344         if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
 345                 src = dst;
 346
 347         if (!(option_mask32 & DAD) || src.s_addr) {
 348                 struct sockaddr_in saddr;
 349                 int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
 350
 351                 setsockopt_bindtodevice(probe_fd, device);
 352                 memset(&saddr, 0, sizeof(saddr));
 353                 saddr.sin_family = AF_INET;
 354                 if (src.s_addr) {
 355                         /* Check that this is indeed our IP */
 356                         saddr.sin_addr = src;
 357                         xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 358                 } else { /* !(option_mask32 & DAD) case */
 359                         /* Find IP address on this iface */
 360                         socklen_t alen = sizeof(saddr);
 361
 362                         saddr.sin_port = htons(1025);
 363                         saddr.sin_addr = dst;
 364
 365                         if (setsockopt_SOL_SOCKET_1(probe_fd, SO_DONTROUTE) != 0)
 366                                 bb_perror_msg("setsockopt(%s)", "SO_DONTROUTE");
 367                         xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 368                         getsockname(probe_fd, (struct sockaddr *) &saddr, &alen);
 369                         //never happens:
 370                         //if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1)
 371                         //      bb_perror_msg_and_die("getsockname");
 372                         if (saddr.sin_family != AF_INET)
 373                                 bb_error_msg_and_die("no IP address configured");
 374                         src = saddr.sin_addr;
 375                 }
 376                 close(probe_fd);
 377         }
 378
 379         me.sll_family = AF_PACKET;
 380         //me.sll_ifindex = ifindex; - done before
 381         me.sll_protocol = htons(ETH_P_ARP);
 382         xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
 383
 384         {
 385                 socklen_t alen = sizeof(me);
 386                 getsockname(sock_fd, (struct sockaddr *) &me, &alen);
 387                 //never happens:
 388                 //if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
 389                 //      bb_perror_msg_and_die("getsockname");
 390         }
 391         if (me.sll_halen == 0) {
 392                 bb_error_msg(err_str, "is not ARPable (no ll address)");
 393                 return (option_mask32 & DAD ? 0 : 2);
 394         }
 395         he = me;
 396         memset(he.sll_addr, -1, he.sll_halen);
 397
 398         if (!(option_mask32 & QUIET)) {
 399                 /* inet_ntoa uses static storage, can't use in same printf */
 400                 printf("ARPING to %s", inet_ntoa(dst));
 401                 printf(" from %s via %s\n", inet_ntoa(src), device);
 402         }
 403
 404         signal_SA_RESTART_empty_mask(SIGINT,  (void (*)(int))finish);
 405         signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
 406
 407         catcher();
 408
 409         packet = xmalloc(4096);
 410         while (1) {
 411                 sigset_t sset, osset;
 412                 struct sockaddr_ll from;
 413                 socklen_t alen = sizeof(from);
 414                 int cc;
 415
 416                 cc = recvfrom(sock_fd, packet, 4096, 0, (struct sockaddr *) &from, &alen);
 417                 if (cc < 0) {
 418                         bb_perror_msg("recvfrom");
 419                         continue;
 420                 }
 421                 sigemptyset(&sset);
 422                 sigaddset(&sset, SIGALRM);
 423                 sigaddset(&sset, SIGINT);
 424                 sigprocmask(SIG_BLOCK, &sset, &osset);
 425                 recv_pack(packet, cc, &from);
 426                 sigprocmask(SIG_SETMASK, &osset, NULL);
 427         }
 428 }