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

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * arping.c - Ping hosts by ARP requests/replies
   4  *
   5  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   6  *
   7  * Author:      Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
   8  * Busybox port: Nick Fedchik <nick@fedchik.org.ua>
   9  */
  10
  11 #include <arpa/inet.h>
  12 #include <net/if.h>
  13 #include <netinet/ether.h>
  14 #include <netpacket/packet.h>
  15
  16 #include "libbb.h"
  17
  18 /* We don't expect to see 1000+ seconds delay, unsigned is enough */
  19 #define MONOTONIC_US() ((unsigned)monotonic_us())
  20
  21 enum {
  22         DAD = 1,
  23         UNSOLICITED = 2,
  24         ADVERT = 4,
  25         QUIET = 8,
  26         QUIT_ON_REPLY = 16,
  27         BCAST_ONLY = 32,
  28         UNICASTING = 64
  29 };
  30
  31 struct globals {
  32         struct in_addr src;
  33         struct in_addr dst;
  34         struct sockaddr_ll me;
  35         struct sockaddr_ll he;
  36         int sock_fd;
  37
  38         int count; // = -1;
  39         unsigned last;
  40         unsigned timeout_us;
  41         unsigned start;
  42
  43         unsigned sent;
  44         unsigned brd_sent;
  45         unsigned received;
  46         unsigned brd_recv;
  47         unsigned req_recv;
  48 };
  49 #define G (*(struct globals*)&bb_common_bufsiz1)
  50 #define src        (G.src       )
  51 #define dst        (G.dst       )
  52 #define me         (G.me        )
  53 #define he         (G.he        )
  54 #define sock_fd    (G.sock_fd   )
  55 #define count      (G.count     )
  56 #define last       (G.last      )
  57 #define timeout_us (G.timeout_us)
  58 #define start      (G.start     )
  59 #define sent       (G.sent      )
  60 #define brd_sent   (G.brd_sent  )
  61 #define received   (G.received  )
  62 #define brd_recv   (G.brd_recv  )
  63 #define req_recv   (G.req_recv  )
  64 #define INIT_G() do { \
  65         count = -1; \
  66 } while (0)
  67
  68 // If GNUisms are not available...
  69 //static void *mempcpy(void *_dst, const void *_src, int n)
  70 //{
  71 //      memcpy(_dst, _src, n);
  72 //      return (char*)_dst + n;
  73 //}
  74
  75 static int send_pack(struct in_addr *src_addr,
  76                         struct in_addr *dst_addr, struct sockaddr_ll *ME,
  77                         struct sockaddr_ll *HE)
  78 {
  79         int err;
  80         unsigned char buf[256];
  81         struct arphdr *ah = (struct arphdr *) buf;
  82         unsigned char *p = (unsigned char *) (ah + 1);
  83
  84         ah->ar_hrd = htons(ARPHRD_ETHER);
  85         ah->ar_pro = htons(ETH_P_IP);
  86         ah->ar_hln = ME->sll_halen;
  87         ah->ar_pln = 4;
  88         ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
  89
  90         p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
  91         p = mempcpy(p, src_addr, 4);
  92
  93         if (option_mask32 & ADVERT)
  94                 p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
  95         else
  96                 p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
  97
  98         p = mempcpy(p, dst_addr, 4);
  99
 100         err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
 101         if (err == p - buf) {
 102                 last = MONOTONIC_US();
 103                 sent++;
 104                 if (!(option_mask32 & UNICASTING))
 105                         brd_sent++;
 106         }
 107         return err;
 108 }
 109
 110 static void finish(void) NORETURN;
 111 static void finish(void)
 112 {
 113         if (!(option_mask32 & QUIET)) {
 114                 printf("Sent %u probe(s) (%u broadcast(s))\n"
 115                         "Received %u repl%s"
 116                         " (%u request(s), %u broadcast(s))\n",
 117                         sent, brd_sent,
 118                         received, (received == 1) ? "ies" : "y",
 119                         req_recv, brd_recv);
 120         }
 121         if (option_mask32 & DAD)
 122                 exit(!!received);
 123         if (option_mask32 & UNSOLICITED)
 124                 exit(EXIT_SUCCESS);
 125         exit(!received);
 126 }
 127
 128 static void catcher(void)
 129 {
 130         unsigned now;
 131
 132         now = MONOTONIC_US();
 133         if (start == 0)
 134                 start = now;
 135
 136         if (count == 0 || (timeout_us && (now - start) > timeout_us))
 137                 finish();
 138
 139         /* count < 0 means "infinite count" */
 140         if (count > 0)
 141                 count--;
 142
 143         if (last == 0 || (now - last) > 500000) {
 144                 send_pack(&src, &dst, &me, &he);
 145                 if (count == 0 && (option_mask32 & UNSOLICITED))
 146                         finish();
 147         }
 148         alarm(1);
 149 }
 150
 151 static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
 152 {
 153         struct arphdr *ah = (struct arphdr *) buf;
 154         unsigned char *p = (unsigned char *) (ah + 1);
 155         struct in_addr src_ip, dst_ip;
 156         /* moves below assume in_addr is 4 bytes big, ensure that */
 157         struct BUG_in_addr_must_be_4 {
 158                 char BUG_in_addr_must_be_4[
 159                         sizeof(struct in_addr) == 4 ? 1 : -1
 160                 ];
 161                 char BUG_s_addr_must_be_4[
 162                         sizeof(src_ip.s_addr) == 4 ? 1 : -1
 163                 ];
 164         };
 165
 166         /* Filter out wild packets */
 167         if (FROM->sll_pkttype != PACKET_HOST
 168          && FROM->sll_pkttype != PACKET_BROADCAST
 169          && FROM->sll_pkttype != PACKET_MULTICAST)
 170                 return false;
 171
 172         /* Only these types are recognised */
 173         if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
 174                 return false;
 175
 176         /* ARPHRD check and this darned FDDI hack here :-( */
 177         if (ah->ar_hrd != htons(FROM->sll_hatype)
 178          && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
 179                 return false;
 180
 181         /* Protocol must be IP. */
 182         if (ah->ar_pro != htons(ETH_P_IP)
 183          || (ah->ar_pln != 4)
 184          || (ah->ar_hln != me.sll_halen)
 185          || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
 186                 return false;
 187
 188         move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
 189         move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
 190
 191         if (dst.s_addr != src_ip.s_addr)
 192                 return false;
 193         if (!(option_mask32 & DAD)) {
 194                 if ((src.s_addr != dst_ip.s_addr)
 195                         || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
 196                         return false;
 197         } else {
 198                 /* DAD packet was:
 199                    src_ip = 0 (or some src)
 200                    src_hw = ME
 201                    dst_ip = tested address
 202                    dst_hw = <unspec>
 203
 204                    We fail, if receive request/reply with:
 205                    src_ip = tested_address
 206                    src_hw != ME
 207                    if src_ip in request was not zero, check
 208                    also that it matches to dst_ip, otherwise
 209                    dst_ip/dst_hw do not matter.
 210                  */
 211                 if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
 212                  || (src.s_addr && src.s_addr != dst_ip.s_addr))
 213                         return false;
 214         }
 215         if (!(option_mask32 & QUIET)) {
 216                 int s_printed = 0;
 217
 218                 printf("%scast re%s from %s [%s]",
 219                         FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
 220                         ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
 221                         inet_ntoa(src_ip),
 222                         ether_ntoa((struct ether_addr *) p));
 223                 if (dst_ip.s_addr != src.s_addr) {
 224                         printf("for %s ", inet_ntoa(dst_ip));
 225                         s_printed = 1;
 226                 }
 227                 if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
 228                         if (!s_printed)
 229                                 printf("for ");
 230                         printf("[%s]",
 231                                 ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4));
 232                 }
 233
 234                 if (last) {
 235                         unsigned diff = MONOTONIC_US() - last;
 236                         printf(" %u.%03ums\n", diff / 1000, diff % 1000);
 237                 } else {
 238                         printf(" UNSOLICITED?\n");
 239                 }
 240                 fflush(stdout);
 241         }
 242         received++;
 243         if (FROM->sll_pkttype != PACKET_HOST)
 244                 brd_recv++;
 245         if (ah->ar_op == htons(ARPOP_REQUEST))
 246                 req_recv++;
 247         if (option_mask32 & QUIT_ON_REPLY)
 248                 finish();
 249         if (!(option_mask32 & BCAST_ONLY)) {
 250                 memcpy(he.sll_addr, p, me.sll_halen);
 251                 option_mask32 |= UNICASTING;
 252         }
 253         return true;
 254 }
 255
 256 int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
 257 int arping_main(int argc UNUSED_PARAM, char **argv)
 258 {
 259         const char *device = "eth0";
 260         char *source = NULL;
 261         char *target;
 262         unsigned char *packet;
 263         char *err_str;
 264
 265         INIT_G();
 266
 267         sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0);
 268
 269         // Drop suid root privileges
 270         // Need to remove SUID_NEVER from applets.h for this to work
 271         //xsetuid(getuid());
 272
 273         err_str = xasprintf("interface %s %%s", device);
 274         {
 275                 unsigned opt;
 276                 char *str_timeout;
 277
 278                 /* Dad also sets quit_on_reply.
 279                  * Advert also sets unsolicited.
 280                  */
 281                 opt_complementary = "=1:Df:AU:c+";
 282                 opt = getopt32(argv, "DUAqfbc:w:I:s:",
 283                                 &count, &str_timeout, &device, &source);
 284                 if (opt & 0x80) /* -w: timeout */
 285                         timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
 286                 //if (opt & 0x200) /* -s: source */
 287                 option_mask32 &= 0x3f; /* set respective flags */
 288         }
 289
 290         target = argv[optind];
 291
 292         xfunc_error_retval = 2;
 293
 294         {
 295                 struct ifreq ifr;
 296
 297                 memset(&ifr, 0, sizeof(ifr));
 298                 strncpy_IFNAMSIZ(ifr.ifr_name, device);
 299                 /* We use ifr.ifr_name in error msg so that problem
 300                  * with truncated name will be visible */
 301                 ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found");
 302                 me.sll_ifindex = ifr.ifr_ifindex;
 303
 304                 xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr);
 305
 306                 if (!(ifr.ifr_flags & IFF_UP)) {
 307                         bb_error_msg_and_die(err_str, "is down");
 308                 }
 309                 if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
 310                         bb_error_msg(err_str, "is not ARPable");
 311                         return (option_mask32 & DAD ? 0 : 2);
 312                 }
 313         }
 314
 315         /* if (!inet_aton(target, &dst)) - not needed */ {
 316                 len_and_sockaddr *lsa;
 317                 lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
 318                 dst = lsa->u.sin.sin_addr;
 319                 if (ENABLE_FEATURE_CLEAN_UP)
 320                         free(lsa);
 321         }
 322
 323         if (source && !inet_aton(source, &src)) {
 324                 bb_error_msg_and_die("invalid source address %s", source);
 325         }
 326
 327         if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
 328                 src = dst;
 329
 330         if (!(option_mask32 & DAD) || src.s_addr) {
 331                 struct sockaddr_in saddr;
 332                 int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
 333
 334                 setsockopt_bindtodevice(probe_fd, device);
 335                 memset(&saddr, 0, sizeof(saddr));
 336                 saddr.sin_family = AF_INET;
 337                 if (src.s_addr) {
 338                         /* Check that this is indeed our IP */
 339                         saddr.sin_addr = src;
 340                         xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 341                 } else { /* !(option_mask32 & DAD) case */
 342                         /* Find IP address on this iface */
 343                         socklen_t alen = sizeof(saddr);
 344
 345                         saddr.sin_port = htons(1025);
 346                         saddr.sin_addr = dst;
 347
 348                         if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, &const_int_1, sizeof(const_int_1)) == -1)
 349                                 bb_perror_msg("setsockopt(SO_DONTROUTE)");
 350                         xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
 351                         if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1) {
 352                                 bb_perror_msg_and_die("getsockname");
 353                         }
 354                         if (saddr.sin_family != AF_INET)
 355                                 bb_error_msg_and_die("no IP address configured");
 356                         src = saddr.sin_addr;
 357                 }
 358                 close(probe_fd);
 359         }
 360
 361         me.sll_family = AF_PACKET;
 362         //me.sll_ifindex = ifindex; - done before
 363         me.sll_protocol = htons(ETH_P_ARP);
 364         xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
 365
 366         {
 367                 socklen_t alen = sizeof(me);
 368
 369                 if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1) {
 370                         bb_perror_msg_and_die("getsockname");
 371                 }
 372         }
 373         if (me.sll_halen == 0) {
 374                 bb_error_msg(err_str, "is not ARPable (no ll address)");
 375                 return (option_mask32 & DAD ? 0 : 2);
 376         }
 377         he = me;
 378         memset(he.sll_addr, -1, he.sll_halen);
 379
 380         if (!(option_mask32 & QUIET)) {
 381                 /* inet_ntoa uses static storage, can't use in same printf */
 382                 printf("ARPING to %s", inet_ntoa(dst));
 383                 printf(" from %s via %s\n", inet_ntoa(src), device);
 384         }
 385
 386         signal_SA_RESTART_empty_mask(SIGINT,  (void (*)(int))finish);
 387         signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
 388
 389         catcher();
 390
 391         packet = xmalloc(4096);
 392         while (1) {
 393                 sigset_t sset, osset;
 394                 struct sockaddr_ll from;
 395                 socklen_t alen = sizeof(from);
 396                 int cc;
 397
 398                 cc = recvfrom(sock_fd, packet, 4096, 0, (struct sockaddr *) &from, &alen);
 399                 if (cc < 0) {
 400                         bb_perror_msg("recvfrom");
 401                         continue;
 402                 }
 403                 sigemptyset(&sset);
 404                 sigaddset(&sset, SIGALRM);
 405                 sigaddset(&sset, SIGINT);
 406                 sigprocmask(SIG_BLOCK, &sset, &osset);
 407                 recv_pack(packet, cc, &from);
 408                 sigprocmask(SIG_SETMASK, &osset, NULL);
 409         }
 410 }