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              Duplicated address detection mode"
  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      Time to wait for ARP reply, seconds"
  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
  32 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
  33 #define MONOTONIC_US() ((unsigned)monotonic_us())
  34
  35 enum {
  36         DAD = 1,
  37         UNSOLICITED = 2,
  38         ADVERT = 4,
  39         QUIET = 8,
  40         QUIT_ON_REPLY = 16,
  41         BCAST_ONLY = 32,
  42         UNICASTING = 64
  43 };
  44
  45 struct globals {
  46         struct in_addr src;
  47         struct in_addr dst;
  48         struct sockaddr_ll me;
  49         struct sockaddr_ll he;
  50         int sock_fd;
  51
  52         int count; // = -1;
  53         unsigned last;
  54         unsigned timeout_us;
  55         unsigned start;
  56
  57         unsigned sent;
  58         unsigned brd_sent;
  59         unsigned received;
  60         unsigned brd_recv;
  61         unsigned req_recv;
  62 } FIX_ALIASING;
  63 #define G (*(struct globals*)&bb_common_bufsiz1)
  64 #define src        (G.src       )
  65 #define dst        (G.dst       )
  66 #define me         (G.me        )
  67 #define he         (G.he        )
  68 #define sock_fd    (G.sock_fd   )
  69 #define count      (G.count     )
  70 #define last       (G.last      )
  71 #define timeout_us (G.timeout_us)
  72 #define start      (G.start     )
  73 #define sent       (G.sent      )
  74 #define brd_sent   (G.brd_sent  )
  75 #define received   (G.received  )
  76 #define brd_recv   (G.brd_recv  )
  77 #define req_recv   (G.req_recv  )
  78 #define INIT_G() do { \
  79         count = -1; \
  80 } while (0)
  81
  82 // If GNUisms are not available...
  83 //static void *mempcpy(void *_dst, const void *_src, int n)
  84 //{
  85 //      memcpy(_dst, _src, n);
  86 //      return (char*)_dst + n;
  87 //}
  88
  89 static int send_pack(struct in_addr *src_addr,
  90                         struct in_addr *dst_addr, struct sockaddr_ll *ME,
  91                         struct sockaddr_ll *HE)
  92 {
  93         int err;
  94         unsigned char buf[256];
  95         struct arphdr *ah = (struct arphdr *) buf;
  96         unsigned char *p = (unsigned char *) (ah + 1);
  97
  98         ah->ar_hrd = htons(ARPHRD_ETHER);
  99         ah->ar_pro = htons(ETH_P_IP);
 100         ah->ar_hln = ME->sll_halen;
 101         ah->ar_pln = 4;
 102         ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
 103
 104         p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
 105         p = mempcpy(p, src_addr, 4);
 106
 107         if (option_mask32 & ADVERT)
 108                 p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
 109         else
 110                 p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
 111
 112         p = mempcpy(p, dst_addr, 4);
 113
 114         err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
 115         if (err == p - buf) {
 116                 last = MONOTONIC_US();
 117                 sent++;
 118                 if (!(option_mask32 & UNICASTING))
 119                         brd_sent++;
 120         }
 121         return err;
 122 }
 123
 124 static void finish(void) NORETURN;
 125 static void finish(void)
 126 {
 127         if (!(option_mask32 & QUIET)) {
 128                 printf("Sent %u probe(s) (%u broadcast(s))\n"
 129                         "Received %u repl%s"
 130                         " (%u request(s), %u broadcast(s))\n",
 131                         sent, brd_sent,
 132                         received, (received == 1) ? "ies" : "y",
 133                         req_recv, brd_recv);
 134         }
 135         if (option_mask32 & DAD)
 136                 exit(!!received);
 137         if (option_mask32 & UNSOLICITED)
 138                 exit(EXIT_SUCCESS);
 139         exit(!received);
 140 }
 141
 142 static void catcher(void)
 143 {
 144         unsigned now;
 145
 146         now = MONOTONIC_US();
 147         if (start == 0)
 148                 start = now;
 149
 150         if (count == 0 || (timeout_us && (now - start) > timeout_us))
 151                 finish();
 152
 153         /* count < 0 means "infinite count" */
 154         if (count > 0)
 155                 count--;
 156
 157         if (last == 0 || (now - last) > 500000) {
 158                 send_pack(&src, &dst, &me, &he);
 159                 if (count == 0 && (option_mask32 & UNSOLICITED))
 160                         finish();
 161         }
 162         alarm(1);
 163 }
 164
 165 static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
 166 {
 167         struct arphdr *ah = (struct arphdr *) buf;
 168         unsigned char *p = (unsigned char *) (ah + 1);
 169         struct in_addr src_ip, dst_ip;
 170         /* moves below assume in_addr is 4 bytes big, ensure that */
 171         struct BUG_in_addr_must_be_4 {
 172                 char BUG_in_addr_must_be_4[
 173                         sizeof(struct in_addr) == 4 ? 1 : -1
 174                 ];
 175                 char BUG_s_addr_must_be_4[
 176                         sizeof(src_ip.s_addr) == 4 ? 1 : -1
 177                 ];
 178         };
 179
 180         /* Filter out wild packets */
 181         if (FROM->sll_pkttype != PACKET_HOST
 182          && FROM->sll_pkttype != PACKET_BROADCAST
 183          && FROM->sll_pkttype != PACKET_MULTICAST)
 184                 return false;
 185
 186         /* Only these types are recognized */
 187         if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
 188                 return false;
 189
 190         /* ARPHRD check and this darned FDDI hack here :-( */
 191         if (ah->ar_hrd != htons(FROM->sll_hatype)
 192          && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
 193                 return false;
 194
 195         /* Protocol must be IP. */
 196         if (ah->ar_pro != htons(ETH_P_IP)
 197          || (ah->ar_pln != 4)
 198          || (ah->ar_hln != me.sll_halen)
 199          || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
 200                 return false;
 201
 202         move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
 203         move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
 204
 205         if (dst.s_addr != src_ip.s_addr)
 206                 return false;
 207         if (!(option_mask32 & DAD)) {
 208                 if ((src.s_addr != dst_ip.s_addr)
 209                         || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
 210                         return false;
 211         } else {
 212                 /* DAD packet was:
 213                    src_ip = 0 (or some src)
 214                    src_hw = ME
 215                    dst_ip = tested address
 216                    dst_hw = <unspec>
 217
 218                    We fail, if receive request/reply with:
 219                    src_ip = tested_address
 220                    src_hw != ME
 221                    if src_ip in request was not zero, check
 222                    also that it matches to dst_ip, otherwise
 223                    dst_ip/dst_hw do not matter.
 224                  */
 225                 if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
 226                  || (src.s_addr && src.s_addr != dst_ip.s_addr))
 227                         return false;
 228         }
 229         if (!(option_mask32 & QUIET)) {
 230                 int s_printed = 0;
 231
 232                 printf("%scast re%s from %s [%s]",
 233                         FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
 234                         ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
 235                         inet_ntoa(src_ip),
 236                         ether_ntoa((struct ether_addr *) p));
 237                 if (dst_ip.s_addr != src.s_addr) {
 238                         printf("for %s ", inet_ntoa(dst_ip));
 239                         s_printed = 1;
 240                 }
 241                 if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
 242                         if (!s_printed)
 243                                 printf("for ");
 244                         printf("[%s]",
 245                                 ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4));
 246                 }
 247
 248                 if (last) {
 249                         unsigned diff = MONOTONIC_US() - last;
 250                         printf(" %u.%03ums\n", diff / 1000, diff % 1000);
 251                 } else {
 252                         printf(" UNSOLICITED?\n");
 253                 }
 254                 fflush_all();
 255         }
 256         received++;
 257         if (FROM->sll_pkttype != PACKET_HOST)
 258                 brd_recv++;
 259         if (ah->ar_op == htons(ARPOP_REQUEST))
 260                 req_recv++;
 261         if (option_mask32 & QUIT_ON_REPLY)
 262                 finish();
 263         if (!(option_mask32 & BCAST_ONLY)) {
 264                 memcpy(he.sll_addr, p, me.sll_halen);
 265                 option_mask32 |= UNICASTING;
 266         }
 267         return true;
 268 }
 269
 270 int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 271 int arping_main(int argc UNUSED_PARAM, char **argv)
 272 {
 273         const char *device = "eth0";
 274         char *source = NULL;
 275         char *target;
 276         unsigned char *packet;
 277         char *err_str;
 278
 279         INIT_G();
 280
 281         sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0);
 282
 283         // Drop suid root privileges
 284         // Need to remove SUID_NEVER from applets.h for this to work
 285         //xsetuid(getuid());
 286
 287         err_str = xasprintf("interface %s %%s", device);
 288         {
 289                 unsigned opt;
 290                 char *str_timeout;
 291
 292                 /* Dad also sets quit_on_reply.
 293                  * Advert also sets unsolicited.
 294                  */
 295                 opt_complementary = "=1:Df:AU:c+";
 296                 opt = getopt32(argv, "DUAqfbc:w:I:s:",
 297                                 &count, &str_timeout, &device, &source);
 298                 if (opt & 0x80) /* -w: timeout */
 299                         timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
 300                 //if (opt & 0x200) /* -s: source */
 301                 option_mask32 &= 0x3f; /* set respective flags */
 302         }
 303
 304         target = argv[optind];
 305
 306         xfunc_error_retval = 2;
 307
 308         {
 309                 struct ifreq ifr;
 310
 311                 memset(&ifr, 0, sizeof(ifr));
 312                 strncpy_IFNAMSIZ(ifr.ifr_name, device);
 313                 /* We use ifr.ifr_name in error msg so that problem
 314                  * with truncated name will be visible */
 315                 ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found");
 316                 me.sll_ifindex = ifr.ifr_ifindex;
 317
 318                 xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr);
 319
 320                 if (!(ifr.ifr_flags & IFF_UP)) {
 321                         bb_error_msg_and_die(err_str, "is down");
 322                 }
 323                 if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
 324                         bb_error_msg(err_str, "is not ARPable");
 325                         return (option_mask32 & DAD ? 0 : 2);
 326                 }
 327         }
 328
 329         /* if (!inet_aton(target, &dst)) - not needed */ {
 330                 len_and_sockaddr *lsa;
 331                 lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
 332                 dst = lsa->u.sin.sin_addr;
 333                 if (ENABLE_FEATURE_CLEAN_UP)
 334                         free(lsa);
 335         }
 336
 337         if (source && !inet_aton(source, &src)) {
 338                 bb_error_msg_and_die("invalid source address %s", source);
 339         }
 340
 341         if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
 342                 src = dst;
 343
 344         if (!(option_mask32 & DAD) || src.s_addr) {
 345                 struct sockaddr_in saddr;
 346                 int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
 347
 348                 setsockopt_bindtodevice(probe_fd, device);
 349                 memset(&saddr, 0, sizeof(saddr));
 350                 saddr.sin_family = AF_INET;
 351                 if (src.s_addr) {
 352                         /* Check that this is indeed our IP */
 353                         saddr.sin_addr = src;
 354                         xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 355                 } else { /* !(option_mask32 & DAD) case */
 356                         /* Find IP address on this iface */
 357                         socklen_t alen = sizeof(saddr);
 358
 359                         saddr.sin_port = htons(1025);
 360                         saddr.sin_addr = dst;
 361
 362                         if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, &const_int_1, sizeof(const_int_1)) == -1)
 363                                 bb_perror_msg("setsockopt(SO_DONTROUTE)");
 364                         xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 365                         getsockname(probe_fd, (struct sockaddr *) &saddr, &alen);
 366                         //never happens:
 367                         //if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1)
 368                         //      bb_perror_msg_and_die("getsockname");
 369                         if (saddr.sin_family != AF_INET)
 370                                 bb_error_msg_and_die("no IP address configured");
 371                         src = saddr.sin_addr;
 372                 }
 373                 close(probe_fd);
 374         }
 375
 376         me.sll_family = AF_PACKET;
 377         //me.sll_ifindex = ifindex; - done before
 378         me.sll_protocol = htons(ETH_P_ARP);
 379         xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
 380
 381         {
 382                 socklen_t alen = sizeof(me);
 383                 getsockname(sock_fd, (struct sockaddr *) &me, &alen);
 384                 //never happens:
 385                 //if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
 386                 //      bb_perror_msg_and_die("getsockname");
 387         }
 388         if (me.sll_halen == 0) {
 389                 bb_error_msg(err_str, "is not ARPable (no ll address)");
 390                 return (option_mask32 & DAD ? 0 : 2);
 391         }
 392         he = me;
 393         memset(he.sll_addr, -1, he.sll_halen);
 394
 395         if (!(option_mask32 & QUIET)) {
 396                 /* inet_ntoa uses static storage, can't use in same printf */
 397                 printf("ARPING to %s", inet_ntoa(dst));
 398                 printf(" from %s via %s\n", inet_ntoa(src), device);
 399         }
 400
 401         signal_SA_RESTART_empty_mask(SIGINT,  (void (*)(int))finish);
 402         signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
 403
 404         catcher();
 405
 406         packet = xmalloc(4096);
 407         while (1) {
 408                 sigset_t sset, osset;
 409                 struct sockaddr_ll from;
 410                 socklen_t alen = sizeof(from);
 411                 int cc;
 412
 413                 cc = recvfrom(sock_fd, packet, 4096, 0, (struct sockaddr *) &from, &alen);
 414                 if (cc < 0) {
 415                         bb_perror_msg("recvfrom");
 416                         continue;
 417                 }
 418                 sigemptyset(&sset);
 419                 sigaddset(&sset, SIGALRM);
 420                 sigaddset(&sset, SIGINT);
 421                 sigprocmask(SIG_BLOCK, &sset, &osset);
 422                 recv_pack(packet, cc, &from);
 423                 sigprocmask(SIG_SETMASK, &osset, NULL);
 424         }
 425 }