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 #include <arpa/inet.h>
  10 #include <net/if.h>
  11 #include <netinet/ether.h>
  12 #include <netpacket/packet.h>
  13
  14 #include "libbb.h"
  15
  16 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
  17 #define MONOTONIC_US() ((unsigned)monotonic_us())
  18
  19 enum {
  20         DAD = 1,
  21         UNSOLICITED = 2,
  22         ADVERT = 4,
  23         QUIET = 8,
  24         QUIT_ON_REPLY = 16,
  25         BCAST_ONLY = 32,
  26         UNICASTING = 64
  27 };
  28
  29 struct globals {
  30         struct in_addr src;
  31         struct in_addr dst;
  32         struct sockaddr_ll me;
  33         struct sockaddr_ll he;
  34         int sock_fd;
  35
  36         int count; // = -1;
  37         unsigned last;
  38         unsigned timeout_us;
  39         unsigned start;
  40
  41         unsigned sent;
  42         unsigned brd_sent;
  43         unsigned received;
  44         unsigned brd_recv;
  45         unsigned req_recv;
  46 } FIX_ALIASING;
  47 #define G (*(struct globals*)&bb_common_bufsiz1)
  48 #define src        (G.src       )
  49 #define dst        (G.dst       )
  50 #define me         (G.me        )
  51 #define he         (G.he        )
  52 #define sock_fd    (G.sock_fd   )
  53 #define count      (G.count     )
  54 #define last       (G.last      )
  55 #define timeout_us (G.timeout_us)
  56 #define start      (G.start     )
  57 #define sent       (G.sent      )
  58 #define brd_sent   (G.brd_sent  )
  59 #define received   (G.received  )
  60 #define brd_recv   (G.brd_recv  )
  61 #define req_recv   (G.req_recv  )
  62 #define INIT_G() do { \
  63         count = -1; \
  64 } while (0)
  65
  66 // If GNUisms are not available...
  67 //static void *mempcpy(void *_dst, const void *_src, int n)
  68 //{
  69 //      memcpy(_dst, _src, n);
  70 //      return (char*)_dst + n;
  71 //}
  72
  73 static int send_pack(struct in_addr *src_addr,
  74                         struct in_addr *dst_addr, struct sockaddr_ll *ME,
  75                         struct sockaddr_ll *HE)
  76 {
  77         int err;
  78         unsigned char buf[256];
  79         struct arphdr *ah = (struct arphdr *) buf;
  80         unsigned char *p = (unsigned char *) (ah + 1);
  81
  82         ah->ar_hrd = htons(ARPHRD_ETHER);
  83         ah->ar_pro = htons(ETH_P_IP);
  84         ah->ar_hln = ME->sll_halen;
  85         ah->ar_pln = 4;
  86         ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
  87
  88         p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
  89         p = mempcpy(p, src_addr, 4);
  90
  91         if (option_mask32 & ADVERT)
  92                 p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
  93         else
  94                 p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
  95
  96         p = mempcpy(p, dst_addr, 4);
  97
  98         err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
  99         if (err == p - buf) {
 100                 last = MONOTONIC_US();
 101                 sent++;
 102                 if (!(option_mask32 & UNICASTING))
 103                         brd_sent++;
 104         }
 105         return err;
 106 }
 107
 108 static void finish(void) NORETURN;
 109 static void finish(void)
 110 {
 111         if (!(option_mask32 & QUIET)) {
 112                 printf("Sent %u probe(s) (%u broadcast(s))\n"
 113                         "Received %u repl%s"
 114                         " (%u request(s), %u broadcast(s))\n",
 115                         sent, brd_sent,
 116                         received, (received == 1) ? "ies" : "y",
 117                         req_recv, brd_recv);
 118         }
 119         if (option_mask32 & DAD)
 120                 exit(!!received);
 121         if (option_mask32 & UNSOLICITED)
 122                 exit(EXIT_SUCCESS);
 123         exit(!received);
 124 }
 125
 126 static void catcher(void)
 127 {
 128         unsigned now;
 129
 130         now = MONOTONIC_US();
 131         if (start == 0)
 132                 start = now;
 133
 134         if (count == 0 || (timeout_us && (now - start) > timeout_us))
 135                 finish();
 136
 137         /* count < 0 means "infinite count" */
 138         if (count > 0)
 139                 count--;
 140
 141         if (last == 0 || (now - last) > 500000) {
 142                 send_pack(&src, &dst, &me, &he);
 143                 if (count == 0 && (option_mask32 & UNSOLICITED))
 144                         finish();
 145         }
 146         alarm(1);
 147 }
 148
 149 static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
 150 {
 151         struct arphdr *ah = (struct arphdr *) buf;
 152         unsigned char *p = (unsigned char *) (ah + 1);
 153         struct in_addr src_ip, dst_ip;
 154         /* moves below assume in_addr is 4 bytes big, ensure that */
 155         struct BUG_in_addr_must_be_4 {
 156                 char BUG_in_addr_must_be_4[
 157                         sizeof(struct in_addr) == 4 ? 1 : -1
 158                 ];
 159                 char BUG_s_addr_must_be_4[
 160                         sizeof(src_ip.s_addr) == 4 ? 1 : -1
 161                 ];
 162         };
 163
 164         /* Filter out wild packets */
 165         if (FROM->sll_pkttype != PACKET_HOST
 166          && FROM->sll_pkttype != PACKET_BROADCAST
 167          && FROM->sll_pkttype != PACKET_MULTICAST)
 168                 return false;
 169
 170         /* Only these types are recognized */
 171         if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
 172                 return false;
 173
 174         /* ARPHRD check and this darned FDDI hack here :-( */
 175         if (ah->ar_hrd != htons(FROM->sll_hatype)
 176          && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
 177                 return false;
 178
 179         /* Protocol must be IP. */
 180         if (ah->ar_pro != htons(ETH_P_IP)
 181          || (ah->ar_pln != 4)
 182          || (ah->ar_hln != me.sll_halen)
 183          || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
 184                 return false;
 185
 186         move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
 187         move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
 188
 189         if (dst.s_addr != src_ip.s_addr)
 190                 return false;
 191         if (!(option_mask32 & DAD)) {
 192                 if ((src.s_addr != dst_ip.s_addr)
 193                         || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
 194                         return false;
 195         } else {
 196                 /* DAD packet was:
 197                    src_ip = 0 (or some src)
 198                    src_hw = ME
 199                    dst_ip = tested address
 200                    dst_hw = <unspec>
 201
 202                    We fail, if receive request/reply with:
 203                    src_ip = tested_address
 204                    src_hw != ME
 205                    if src_ip in request was not zero, check
 206                    also that it matches to dst_ip, otherwise
 207                    dst_ip/dst_hw do not matter.
 208                  */
 209                 if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
 210                  || (src.s_addr && src.s_addr != dst_ip.s_addr))
 211                         return false;
 212         }
 213         if (!(option_mask32 & QUIET)) {
 214                 int s_printed = 0;
 215
 216                 printf("%scast re%s from %s [%s]",
 217                         FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
 218                         ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
 219                         inet_ntoa(src_ip),
 220                         ether_ntoa((struct ether_addr *) p));
 221                 if (dst_ip.s_addr != src.s_addr) {
 222                         printf("for %s ", inet_ntoa(dst_ip));
 223                         s_printed = 1;
 224                 }
 225                 if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
 226                         if (!s_printed)
 227                                 printf("for ");
 228                         printf("[%s]",
 229                                 ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4));
 230                 }
 231
 232                 if (last) {
 233                         unsigned diff = MONOTONIC_US() - last;
 234                         printf(" %u.%03ums\n", diff / 1000, diff % 1000);
 235                 } else {
 236                         printf(" UNSOLICITED?\n");
 237                 }
 238                 fflush_all();
 239         }
 240         received++;
 241         if (FROM->sll_pkttype != PACKET_HOST)
 242                 brd_recv++;
 243         if (ah->ar_op == htons(ARPOP_REQUEST))
 244                 req_recv++;
 245         if (option_mask32 & QUIT_ON_REPLY)
 246                 finish();
 247         if (!(option_mask32 & BCAST_ONLY)) {
 248                 memcpy(he.sll_addr, p, me.sll_halen);
 249                 option_mask32 |= UNICASTING;
 250         }
 251         return true;
 252 }
 253
 254 int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 255 int arping_main(int argc UNUSED_PARAM, char **argv)
 256 {
 257         const char *device = "eth0";
 258         char *source = NULL;
 259         char *target;
 260         unsigned char *packet;
 261         char *err_str;
 262
 263         INIT_G();
 264
 265         sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0);
 266
 267         // Drop suid root privileges
 268         // Need to remove SUID_NEVER from applets.h for this to work
 269         //xsetuid(getuid());
 270
 271         err_str = xasprintf("interface %s %%s", device);
 272         {
 273                 unsigned opt;
 274                 char *str_timeout;
 275
 276                 /* Dad also sets quit_on_reply.
 277                  * Advert also sets unsolicited.
 278                  */
 279                 opt_complementary = "=1:Df:AU:c+";
 280                 opt = getopt32(argv, "DUAqfbc:w:I:s:",
 281                                 &count, &str_timeout, &device, &source);
 282                 if (opt & 0x80) /* -w: timeout */
 283                         timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
 284                 //if (opt & 0x200) /* -s: source */
 285                 option_mask32 &= 0x3f; /* set respective flags */
 286         }
 287
 288         target = argv[optind];
 289
 290         xfunc_error_retval = 2;
 291
 292         {
 293                 struct ifreq ifr;
 294
 295                 memset(&ifr, 0, sizeof(ifr));
 296                 strncpy_IFNAMSIZ(ifr.ifr_name, device);
 297                 /* We use ifr.ifr_name in error msg so that problem
 298                  * with truncated name will be visible */
 299                 ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found");
 300                 me.sll_ifindex = ifr.ifr_ifindex;
 301
 302                 xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr);
 303
 304                 if (!(ifr.ifr_flags & IFF_UP)) {
 305                         bb_error_msg_and_die(err_str, "is down");
 306                 }
 307                 if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
 308                         bb_error_msg(err_str, "is not ARPable");
 309                         return (option_mask32 & DAD ? 0 : 2);
 310                 }
 311         }
 312
 313         /* if (!inet_aton(target, &dst)) - not needed */ {
 314                 len_and_sockaddr *lsa;
 315                 lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
 316                 dst = lsa->u.sin.sin_addr;
 317                 if (ENABLE_FEATURE_CLEAN_UP)
 318                         free(lsa);
 319         }
 320
 321         if (source && !inet_aton(source, &src)) {
 322                 bb_error_msg_and_die("invalid source address %s", source);
 323         }
 324
 325         if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
 326                 src = dst;
 327
 328         if (!(option_mask32 & DAD) || src.s_addr) {
 329                 struct sockaddr_in saddr;
 330                 int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
 331
 332                 setsockopt_bindtodevice(probe_fd, device);
 333                 memset(&saddr, 0, sizeof(saddr));
 334                 saddr.sin_family = AF_INET;
 335                 if (src.s_addr) {
 336                         /* Check that this is indeed our IP */
 337                         saddr.sin_addr = src;
 338                         xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 339                 } else { /* !(option_mask32 & DAD) case */
 340                         /* Find IP address on this iface */
 341                         socklen_t alen = sizeof(saddr);
 342
 343                         saddr.sin_port = htons(1025);
 344                         saddr.sin_addr = dst;
 345
 346                         if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, &const_int_1, sizeof(const_int_1)) == -1)
 347                                 bb_perror_msg("setsockopt(SO_DONTROUTE)");
 348                         xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 349                         getsockname(probe_fd, (struct sockaddr *) &saddr, &alen);
 350                         //never happens:
 351                         //if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1)
 352                         //      bb_perror_msg_and_die("getsockname");
 353                         if (saddr.sin_family != AF_INET)
 354                                 bb_error_msg_and_die("no IP address configured");
 355                         src = saddr.sin_addr;
 356                 }
 357                 close(probe_fd);
 358         }
 359
 360         me.sll_family = AF_PACKET;
 361         //me.sll_ifindex = ifindex; - done before
 362         me.sll_protocol = htons(ETH_P_ARP);
 363         xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
 364
 365         {
 366                 socklen_t alen = sizeof(me);
 367                 getsockname(sock_fd, (struct sockaddr *) &me, &alen);
 368                 //never happens:
 369                 //if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
 370                 //      bb_perror_msg_and_die("getsockname");
 371         }
 372         if (me.sll_halen == 0) {
 373                 bb_error_msg(err_str, "is not ARPable (no ll address)");
 374                 return (option_mask32 & DAD ? 0 : 2);
 375         }
 376         he = me;
 377         memset(he.sll_addr, -1, he.sll_halen);
 378
 379         if (!(option_mask32 & QUIET)) {
 380                 /* inet_ntoa uses static storage, can't use in same printf */
 381                 printf("ARPING to %s", inet_ntoa(dst));
 382                 printf(" from %s via %s\n", inet_ntoa(src), device);
 383         }
 384
 385         signal_SA_RESTART_empty_mask(SIGINT,  (void (*)(int))finish);
 386         signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
 387
 388         catcher();
 389
 390         packet = xmalloc(4096);
 391         while (1) {
 392                 sigset_t sset, osset;
 393                 struct sockaddr_ll from;
 394                 socklen_t alen = sizeof(from);
 395                 int cc;
 396
 397                 cc = recvfrom(sock_fd, packet, 4096, 0, (struct sockaddr *) &from, &alen);
 398                 if (cc < 0) {
 399                         bb_perror_msg("recvfrom");
 400                         continue;
 401                 }
 402                 sigemptyset(&sset);
 403                 sigaddset(&sset, SIGALRM);
 404                 sigaddset(&sset, SIGINT);
 405                 sigprocmask(SIG_BLOCK, &sset, &osset);
 406                 recv_pack(packet, cc, &from);
 407                 sigprocmask(SIG_SETMASK, &osset, NULL);
 408         }
 409 }