diff options
Diffstat (limited to 'networking/arping.c')
-rw-r--r-- | networking/arping.c | 401 |
1 files changed, 401 insertions, 0 deletions
diff --git a/networking/arping.c b/networking/arping.c new file mode 100644 index 0000000..021dc86 --- /dev/null +++ b/networking/arping.c @@ -0,0 +1,401 @@ +/* vi: set sw=4 ts=4: */ +/* + * arping.c - Ping hosts by ARP requests/replies + * + * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. + * + * 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; +}; +#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; + + /* 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 recognised */ + 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; + + memcpy(&src_ip, p + ah->ar_hln, 4); + memcpy(&dst_ip, p + ah->ar_hln + 4 + ah->ar_hln, 4); + + 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(stdout); + } + 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(ifr.ifr_name, device, sizeof(ifr.ifr_name) - 1); + /* 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); + memcpy(&dst, &lsa->u.sin.sin_addr.s_addr, 4); + 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)); + 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); + + 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); + } +} |