/* vi: set sw=4 ts=4: */ /* * arping.c - Ping hosts by ARP requests/replies * * Licensed under GPLv2 or later, see file LICENSE in this source tree. * * Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru> * Busybox port: Nick Fedchik <nick@fedchik.org.ua> */ #include <arpa/inet.h> #include <net/if.h> #include <netinet/ether.h> #include <netpacket/packet.h> #include "libbb.h" /* We don't expect to see 1000+ seconds delay, unsigned is enough */ #define MONOTONIC_US() ((unsigned)monotonic_us()) enum { DAD = 1, UNSOLICITED = 2, ADVERT = 4, QUIET = 8, QUIT_ON_REPLY = 16, BCAST_ONLY = 32, UNICASTING = 64 }; struct globals { struct in_addr src; struct in_addr dst; struct sockaddr_ll me; struct sockaddr_ll he; int sock_fd; int count; // = -1; unsigned last; unsigned timeout_us; unsigned start; unsigned sent; unsigned brd_sent; unsigned received; unsigned brd_recv; unsigned req_recv; } FIX_ALIASING; #define G (*(struct globals*)&bb_common_bufsiz1) #define src (G.src ) #define dst (G.dst ) #define me (G.me ) #define he (G.he ) #define sock_fd (G.sock_fd ) #define count (G.count ) #define last (G.last ) #define timeout_us (G.timeout_us) #define start (G.start ) #define sent (G.sent ) #define brd_sent (G.brd_sent ) #define received (G.received ) #define brd_recv (G.brd_recv ) #define req_recv (G.req_recv ) #define INIT_G() do { \ count = -1; \ } while (0) // If GNUisms are not available... //static void *mempcpy(void *_dst, const void *_src, int n) //{ // memcpy(_dst, _src, n); // return (char*)_dst + n; //} static int send_pack(struct in_addr *src_addr, struct in_addr *dst_addr, struct sockaddr_ll *ME, struct sockaddr_ll *HE) { int err; unsigned char buf[256]; struct arphdr *ah = (struct arphdr *) buf; unsigned char *p = (unsigned char *) (ah + 1); ah->ar_hrd = htons(ARPHRD_ETHER); ah->ar_pro = htons(ETH_P_IP); ah->ar_hln = ME->sll_halen; ah->ar_pln = 4; ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST); p = mempcpy(p, &ME->sll_addr, ah->ar_hln); p = mempcpy(p, src_addr, 4); if (option_mask32 & ADVERT) p = mempcpy(p, &ME->sll_addr, ah->ar_hln); else p = mempcpy(p, &HE->sll_addr, ah->ar_hln); p = mempcpy(p, dst_addr, 4); err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE)); if (err == p - buf) { last = MONOTONIC_US(); sent++; if (!(option_mask32 & UNICASTING)) brd_sent++; } return err; } static void finish(void) NORETURN; static void finish(void) { if (!(option_mask32 & QUIET)) { printf("Sent %u probe(s) (%u broadcast(s))\n" "Received %u repl%s" " (%u request(s), %u broadcast(s))\n", sent, brd_sent, received, (received == 1) ? "ies" : "y", req_recv, brd_recv); } if (option_mask32 & DAD) exit(!!received); if (option_mask32 & UNSOLICITED) exit(EXIT_SUCCESS); exit(!received); } static void catcher(void) { unsigned now; now = MONOTONIC_US(); if (start == 0) start = now; if (count == 0 || (timeout_us && (now - start) > timeout_us)) finish(); /* count < 0 means "infinite count" */ if (count > 0) count--; if (last == 0 || (now - last) > 500000) { send_pack(&src, &dst, &me, &he); if (count == 0 && (option_mask32 & UNSOLICITED)) finish(); } alarm(1); } static bool recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM) { struct arphdr *ah = (struct arphdr *) buf; unsigned char *p = (unsigned char *) (ah + 1); struct in_addr src_ip, dst_ip; /* moves below assume in_addr is 4 bytes big, ensure that */ struct BUG_in_addr_must_be_4 { char BUG_in_addr_must_be_4[ sizeof(struct in_addr) == 4 ? 1 : -1 ]; char BUG_s_addr_must_be_4[ sizeof(src_ip.s_addr) == 4 ? 1 : -1 ]; }; /* Filter out wild packets */ if (FROM->sll_pkttype != PACKET_HOST && FROM->sll_pkttype != PACKET_BROADCAST && FROM->sll_pkttype != PACKET_MULTICAST) return false; /* Only these types are recognized */ if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY)) return false; /* ARPHRD check and this darned FDDI hack here :-( */ if (ah->ar_hrd != htons(FROM->sll_hatype) && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER))) return false; /* Protocol must be IP. */ if (ah->ar_pro != htons(ETH_P_IP) || (ah->ar_pln != 4) || (ah->ar_hln != me.sll_halen) || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln)))) return false; move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln); move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln); if (dst.s_addr != src_ip.s_addr) return false; if (!(option_mask32 & DAD)) { if ((src.s_addr != dst_ip.s_addr) || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln))) return false; } else { /* DAD packet was: src_ip = 0 (or some src) src_hw = ME dst_ip = tested address dst_hw = <unspec> We fail, if receive request/reply with: src_ip = tested_address src_hw != ME if src_ip in request was not zero, check also that it matches to dst_ip, otherwise dst_ip/dst_hw do not matter. */ if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0) || (src.s_addr && src.s_addr != dst_ip.s_addr)) return false; } if (!(option_mask32 & QUIET)) { int s_printed = 0; printf("%scast re%s from %s [%s]", FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad", ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest", inet_ntoa(src_ip), ether_ntoa((struct ether_addr *) p)); if (dst_ip.s_addr != src.s_addr) { printf("for %s ", inet_ntoa(dst_ip)); s_printed = 1; } if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) { if (!s_printed) printf("for "); printf("[%s]", ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4)); } if (last) { unsigned diff = MONOTONIC_US() - last; printf(" %u.%03ums\n", diff / 1000, diff % 1000); } else { printf(" UNSOLICITED?\n"); } fflush_all(); } received++; if (FROM->sll_pkttype != PACKET_HOST) brd_recv++; if (ah->ar_op == htons(ARPOP_REQUEST)) req_recv++; if (option_mask32 & QUIT_ON_REPLY) finish(); if (!(option_mask32 & BCAST_ONLY)) { memcpy(he.sll_addr, p, me.sll_halen); option_mask32 |= UNICASTING; } return true; } int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE; int arping_main(int argc UNUSED_PARAM, char **argv) { const char *device = "eth0"; char *source = NULL; char *target; unsigned char *packet; char *err_str; INIT_G(); sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0); // Drop suid root privileges // Need to remove SUID_NEVER from applets.h for this to work //xsetuid(getuid()); err_str = xasprintf("interface %s %%s", device); { unsigned opt; char *str_timeout; /* Dad also sets quit_on_reply. * Advert also sets unsolicited. */ opt_complementary = "=1:Df:AU:c+"; opt = getopt32(argv, "DUAqfbc:w:I:s:", &count, &str_timeout, &device, &source); if (opt & 0x80) /* -w: timeout */ timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000; //if (opt & 0x200) /* -s: source */ option_mask32 &= 0x3f; /* set respective flags */ } target = argv[optind]; xfunc_error_retval = 2; { struct ifreq ifr; memset(&ifr, 0, sizeof(ifr)); strncpy_IFNAMSIZ(ifr.ifr_name, device); /* We use ifr.ifr_name in error msg so that problem * with truncated name will be visible */ ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found"); me.sll_ifindex = ifr.ifr_ifindex; xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr); if (!(ifr.ifr_flags & IFF_UP)) { bb_error_msg_and_die(err_str, "is down"); } if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) { bb_error_msg(err_str, "is not ARPable"); return (option_mask32 & DAD ? 0 : 2); } } /* if (!inet_aton(target, &dst)) - not needed */ { len_and_sockaddr *lsa; lsa = xhost_and_af2sockaddr(target, 0, AF_INET); dst = lsa->u.sin.sin_addr; if (ENABLE_FEATURE_CLEAN_UP) free(lsa); } if (source && !inet_aton(source, &src)) { bb_error_msg_and_die("invalid source address %s", source); } if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0) src = dst; if (!(option_mask32 & DAD) || src.s_addr) { struct sockaddr_in saddr; int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0); setsockopt_bindtodevice(probe_fd, device); memset(&saddr, 0, sizeof(saddr)); saddr.sin_family = AF_INET; if (src.s_addr) { /* Check that this is indeed our IP */ saddr.sin_addr = src; xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr)); } else { /* !(option_mask32 & DAD) case */ /* Find IP address on this iface */ socklen_t alen = sizeof(saddr); saddr.sin_port = htons(1025); saddr.sin_addr = dst; if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, &const_int_1, sizeof(const_int_1)) == -1) bb_perror_msg("setsockopt(SO_DONTROUTE)"); xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr)); getsockname(probe_fd, (struct sockaddr *) &saddr, &alen); //never happens: //if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1) // bb_perror_msg_and_die("getsockname"); if (saddr.sin_family != AF_INET) bb_error_msg_and_die("no IP address configured"); src = saddr.sin_addr; } close(probe_fd); } me.sll_family = AF_PACKET; //me.sll_ifindex = ifindex; - done before me.sll_protocol = htons(ETH_P_ARP); xbind(sock_fd, (struct sockaddr *) &me, sizeof(me)); { socklen_t alen = sizeof(me); getsockname(sock_fd, (struct sockaddr *) &me, &alen); //never happens: //if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1) // bb_perror_msg_and_die("getsockname"); } if (me.sll_halen == 0) { bb_error_msg(err_str, "is not ARPable (no ll address)"); return (option_mask32 & DAD ? 0 : 2); } he = me; memset(he.sll_addr, -1, he.sll_halen); if (!(option_mask32 & QUIET)) { /* inet_ntoa uses static storage, can't use in same printf */ printf("ARPING to %s", inet_ntoa(dst)); printf(" from %s via %s\n", inet_ntoa(src), device); } signal_SA_RESTART_empty_mask(SIGINT, (void (*)(int))finish); signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher); catcher(); packet = xmalloc(4096); while (1) { sigset_t sset, osset; struct sockaddr_ll from; socklen_t alen = sizeof(from); int cc; cc = recvfrom(sock_fd, packet, 4096, 0, (struct sockaddr *) &from, &alen); if (cc < 0) { bb_perror_msg("recvfrom"); continue; } sigemptyset(&sset); sigaddset(&sset, SIGALRM); sigaddset(&sset, SIGINT); sigprocmask(SIG_BLOCK, &sset, &osset); recv_pack(packet, cc, &from); sigprocmask(SIG_SETMASK, &osset, NULL); } }