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