[821] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * arping.c - Ping hosts by ARP requests/replies
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| 4 | *
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| 5 | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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| 6 | *
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| 7 | * Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
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| 8 | * Busybox port: Nick Fedchik <nick@fedchik.org.ua>
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| 9 | */
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| 10 |
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| 11 | #include <arpa/inet.h>
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| 12 | #include <net/if.h>
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| 13 | #include <netinet/ether.h>
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| 14 | #include <netpacket/packet.h>
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| 15 |
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[1770] | 16 | #include "libbb.h"
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[821] | 17 |
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[1770] | 18 | /* We don't expect to see 1000+ seconds delay, unsigned is enough */
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| 19 | #define MONOTONIC_US() ((unsigned)monotonic_us())
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| 20 |
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[821] | 21 | static struct in_addr src;
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| 22 | static struct in_addr dst;
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| 23 | static struct sockaddr_ll me;
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| 24 | static struct sockaddr_ll he;
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[1770] | 25 | static unsigned last;
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[821] | 26 |
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[1770] | 27 | enum {
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| 28 | DAD = 1,
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| 29 | UNSOLICITED = 2,
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| 30 | ADVERT = 4,
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| 31 | QUIET = 8,
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| 32 | QUIT_ON_REPLY = 16,
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| 33 | BCAST_ONLY = 32,
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| 34 | UNICASTING = 64
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[821] | 35 | };
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| 36 |
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[1770] | 37 | static int sock;
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| 38 | static unsigned count = UINT_MAX;
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| 39 | static unsigned timeout_us;
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| 40 | static unsigned sent;
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| 41 | static unsigned brd_sent;
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| 42 | static unsigned received;
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| 43 | static unsigned brd_recv;
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| 44 | static unsigned req_recv;
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[821] | 45 |
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[1770] | 46 | static int send_pack(struct in_addr *src_addr,
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| 47 | struct in_addr *dst_addr, struct sockaddr_ll *ME,
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| 48 | struct sockaddr_ll *HE)
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[821] | 49 | {
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| 50 | int err;
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[1770] | 51 | unsigned now;
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| 52 | unsigned char buf[256];
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[821] | 53 | struct arphdr *ah = (struct arphdr *) buf;
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| 54 | unsigned char *p = (unsigned char *) (ah + 1);
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| 55 |
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| 56 | ah->ar_hrd = htons(ME->sll_hatype);
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| 57 | ah->ar_hrd = htons(ARPHRD_ETHER);
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| 58 | ah->ar_pro = htons(ETH_P_IP);
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| 59 | ah->ar_hln = ME->sll_halen;
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| 60 | ah->ar_pln = 4;
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[1770] | 61 | ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
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[821] | 62 |
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| 63 | memcpy(p, &ME->sll_addr, ah->ar_hln);
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| 64 | p += ME->sll_halen;
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| 65 |
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| 66 | memcpy(p, src_addr, 4);
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| 67 | p += 4;
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| 68 |
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[1770] | 69 | if (option_mask32 & ADVERT)
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[821] | 70 | memcpy(p, &ME->sll_addr, ah->ar_hln);
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| 71 | else
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| 72 | memcpy(p, &HE->sll_addr, ah->ar_hln);
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| 73 | p += ah->ar_hln;
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| 74 |
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| 75 | memcpy(p, dst_addr, 4);
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| 76 | p += 4;
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| 77 |
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[1770] | 78 | now = MONOTONIC_US();
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[821] | 79 | err = sendto(sock, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
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| 80 | if (err == p - buf) {
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| 81 | last = now;
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| 82 | sent++;
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[1770] | 83 | if (!(option_mask32 & UNICASTING))
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[821] | 84 | brd_sent++;
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| 85 | }
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| 86 | return err;
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| 87 | }
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| 88 |
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[1770] | 89 | static void finish(void) ATTRIBUTE_NORETURN;
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[821] | 90 | static void finish(void)
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| 91 | {
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[1770] | 92 | if (!(option_mask32 & QUIET)) {
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| 93 | printf("Sent %u probe(s) (%u broadcast(s))\n"
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| 94 | "Received %u repl%s"
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| 95 | " (%u request(s), %u broadcast(s))\n",
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[821] | 96 | sent, brd_sent,
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[1770] | 97 | received, (received == 1) ? "ies" : "y",
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| 98 | req_recv, brd_recv);
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[821] | 99 | }
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[1770] | 100 | if (option_mask32 & DAD)
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[821] | 101 | exit(!!received);
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[1770] | 102 | if (option_mask32 & UNSOLICITED)
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[821] | 103 | exit(0);
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| 104 | exit(!received);
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| 105 | }
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| 106 |
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| 107 | static void catcher(void)
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| 108 | {
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[1770] | 109 | static unsigned start;
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[821] | 110 |
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[1770] | 111 | unsigned now;
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[821] | 112 |
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[1770] | 113 | now = MONOTONIC_US();
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| 114 | if (start == 0)
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| 115 | start = now;
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[821] | 116 |
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[1770] | 117 | if (count == 0 || (timeout_us && (now - start) > (timeout_us + 500000)))
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[821] | 118 | finish();
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| 119 |
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[1770] | 120 | count--;
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| 121 |
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| 122 | if (last == 0 || (now - last) > 500000) {
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| 123 | send_pack(&src, &dst, &me, &he);
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| 124 | if (count == 0 && (option_mask32 & UNSOLICITED))
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[821] | 125 | finish();
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| 126 | }
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| 127 | alarm(1);
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| 128 | }
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| 129 |
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| 130 | static int recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
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| 131 | {
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| 132 | struct arphdr *ah = (struct arphdr *) buf;
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| 133 | unsigned char *p = (unsigned char *) (ah + 1);
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| 134 | struct in_addr src_ip, dst_ip;
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| 135 |
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| 136 | /* Filter out wild packets */
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[1770] | 137 | if (FROM->sll_pkttype != PACKET_HOST
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| 138 | && FROM->sll_pkttype != PACKET_BROADCAST
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| 139 | && FROM->sll_pkttype != PACKET_MULTICAST)
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[821] | 140 | return 0;
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| 141 |
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| 142 | /* Only these types are recognised */
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| 143 | if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
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| 144 | return 0;
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| 145 |
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| 146 | /* ARPHRD check and this darned FDDI hack here :-( */
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[1770] | 147 | if (ah->ar_hrd != htons(FROM->sll_hatype)
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| 148 | && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
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[821] | 149 | return 0;
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| 150 |
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| 151 | /* Protocol must be IP. */
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| 152 | if (ah->ar_pro != htons(ETH_P_IP))
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| 153 | return 0;
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| 154 | if (ah->ar_pln != 4)
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| 155 | return 0;
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| 156 | if (ah->ar_hln != me.sll_halen)
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| 157 | return 0;
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| 158 | if (len < sizeof(*ah) + 2 * (4 + ah->ar_hln))
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| 159 | return 0;
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| 160 | memcpy(&src_ip, p + ah->ar_hln, 4);
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| 161 | memcpy(&dst_ip, p + ah->ar_hln + 4 + ah->ar_hln, 4);
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[1770] | 162 | if (!(option_mask32 & DAD)) {
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[821] | 163 | if (src_ip.s_addr != dst.s_addr)
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| 164 | return 0;
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| 165 | if (src.s_addr != dst_ip.s_addr)
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| 166 | return 0;
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| 167 | if (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln))
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| 168 | return 0;
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| 169 | } else {
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| 170 | /* DAD packet was:
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| 171 | src_ip = 0 (or some src)
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| 172 | src_hw = ME
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| 173 | dst_ip = tested address
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| 174 | dst_hw = <unspec>
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| 175 |
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| 176 | We fail, if receive request/reply with:
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| 177 | src_ip = tested_address
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| 178 | src_hw != ME
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| 179 | if src_ip in request was not zero, check
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| 180 | also that it matches to dst_ip, otherwise
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| 181 | dst_ip/dst_hw do not matter.
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| 182 | */
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| 183 | if (src_ip.s_addr != dst.s_addr)
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| 184 | return 0;
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| 185 | if (memcmp(p, &me.sll_addr, me.sll_halen) == 0)
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| 186 | return 0;
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| 187 | if (src.s_addr && src.s_addr != dst_ip.s_addr)
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| 188 | return 0;
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| 189 | }
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[1770] | 190 | if (!(option_mask32 & QUIET)) {
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[821] | 191 | int s_printed = 0;
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| 192 |
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[1770] | 193 | printf("%scast re%s from %s [%s]",
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| 194 | FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
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| 195 | ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
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[821] | 196 | inet_ntoa(src_ip),
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| 197 | ether_ntoa((struct ether_addr *) p));
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| 198 | if (dst_ip.s_addr != src.s_addr) {
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| 199 | printf("for %s ", inet_ntoa(dst_ip));
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| 200 | s_printed = 1;
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| 201 | }
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| 202 | if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
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| 203 | if (!s_printed)
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| 204 | printf("for ");
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| 205 | printf("[%s]",
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[1770] | 206 | ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4));
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[821] | 207 | }
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| 208 |
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[1770] | 209 | if (last) {
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| 210 | printf(" %u.%03ums\n", last / 1000, last % 1000);
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[821] | 211 | } else {
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| 212 | printf(" UNSOLICITED?\n");
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| 213 | }
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| 214 | fflush(stdout);
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| 215 | }
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| 216 | received++;
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| 217 | if (FROM->sll_pkttype != PACKET_HOST)
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| 218 | brd_recv++;
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| 219 | if (ah->ar_op == htons(ARPOP_REQUEST))
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| 220 | req_recv++;
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[1770] | 221 | if (option_mask32 & QUIT_ON_REPLY)
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[821] | 222 | finish();
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[1770] | 223 | if (!(option_mask32 & BCAST_ONLY)) {
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[821] | 224 | memcpy(he.sll_addr, p, me.sll_halen);
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[1770] | 225 | option_mask32 |= UNICASTING;
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[821] | 226 | }
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| 227 | return 1;
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| 228 | }
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| 229 |
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[1770] | 230 | int arping_main(int argc, char **argv);
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[821] | 231 | int arping_main(int argc, char **argv)
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| 232 | {
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[1770] | 233 | const char *device = "eth0";
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[821] | 234 | int ifindex;
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| 235 | char *source = NULL;
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| 236 | char *target;
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[1770] | 237 | unsigned char *packet;
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[821] | 238 |
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[1770] | 239 | sock = xsocket(PF_PACKET, SOCK_DGRAM, 0);
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[821] | 240 |
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| 241 | // Drop suid root privileges
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| 242 | xsetuid(getuid());
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| 243 |
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| 244 | {
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[1770] | 245 | unsigned opt;
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| 246 | char *str_count, *str_timeout;
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[821] | 247 |
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| 248 | /* Dad also sets quit_on_reply.
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| 249 | * Advert also sets unsolicited.
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| 250 | */
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[1770] | 251 | opt_complementary = "=1:Df:AU";
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| 252 | opt = getopt32(argv, "DUAqfbc:w:I:s:",
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| 253 | &str_count, &str_timeout, &device, &source);
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| 254 | if (opt & 0x40) /* -c: count */
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| 255 | count = xatou(str_count);
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| 256 | if (opt & 0x80) /* -w: timeout */
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| 257 | timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000;
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| 258 | //if (opt & 0x100) /* -I: interface */
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| 259 | if (strlen(device) >= IF_NAMESIZE) {
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| 260 | bb_error_msg_and_die("interface name '%s' is too long",
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| 261 | device);
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[821] | 262 | }
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[1770] | 263 | //if (opt & 0x200) /* -s: source */
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| 264 | option_mask32 &= 0x3f; /* set respective flags */
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[821] | 265 | }
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| 266 |
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[1770] | 267 | target = argv[optind];
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[821] | 268 |
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[1770] | 269 | xfunc_error_retval = 2;
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[821] | 270 |
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| 271 | {
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| 272 | struct ifreq ifr;
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| 273 |
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| 274 | memset(&ifr, 0, sizeof(ifr));
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| 275 | strncpy(ifr.ifr_name, device, IFNAMSIZ - 1);
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[1770] | 276 | ioctl_or_perror_and_die(sock, SIOCGIFINDEX, &ifr, "interface %s not found", device);
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[821] | 277 | ifindex = ifr.ifr_ifindex;
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| 278 |
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[1770] | 279 | xioctl(sock, SIOCGIFFLAGS, (char *) &ifr);
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| 280 |
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[821] | 281 | if (!(ifr.ifr_flags & IFF_UP)) {
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[1770] | 282 | bb_error_msg_and_die("interface %s is down", device);
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[821] | 283 | }
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| 284 | if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
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[1770] | 285 | bb_error_msg("interface %s is not ARPable", device);
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| 286 | return (option_mask32 & DAD ? 0 : 2);
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[821] | 287 | }
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| 288 | }
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| 289 |
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| 290 | if (!inet_aton(target, &dst)) {
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[1770] | 291 | len_and_sockaddr *lsa;
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| 292 | lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
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| 293 | memcpy(&dst, &lsa->sin.sin_addr.s_addr, 4);
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| 294 | if (ENABLE_FEATURE_CLEAN_UP)
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| 295 | free(lsa);
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[821] | 296 | }
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| 297 |
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| 298 | if (source && !inet_aton(source, &src)) {
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| 299 | bb_error_msg_and_die("invalid source address %s", source);
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| 300 | }
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| 301 |
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[1770] | 302 | if (!(option_mask32 & DAD) && (option_mask32 & UNSOLICITED) && src.s_addr == 0)
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[821] | 303 | src = dst;
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| 304 |
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[1770] | 305 | if (!(option_mask32 & DAD) || src.s_addr) {
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[821] | 306 | struct sockaddr_in saddr;
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[1770] | 307 | int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
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[821] | 308 |
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| 309 | if (device) {
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[1770] | 310 | if (setsockopt(probe_fd, SOL_SOCKET, SO_BINDTODEVICE, device, strlen(device) + 1) == -1)
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| 311 | bb_error_msg("warning: interface %s is ignored", device);
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[821] | 312 | }
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| 313 | memset(&saddr, 0, sizeof(saddr));
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| 314 | saddr.sin_family = AF_INET;
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| 315 | if (src.s_addr) {
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| 316 | saddr.sin_addr = src;
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[1770] | 317 | xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
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| 318 | } else if (!(option_mask32 & DAD)) {
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[821] | 319 | socklen_t alen = sizeof(saddr);
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| 320 |
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| 321 | saddr.sin_port = htons(1025);
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| 322 | saddr.sin_addr = dst;
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| 323 |
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[1770] | 324 | if (setsockopt(probe_fd, SOL_SOCKET, SO_DONTROUTE, &const_int_1, sizeof(const_int_1)) == -1)
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| 325 | bb_perror_msg("warning: setsockopt(SO_DONTROUTE)");
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| 326 | xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
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| 327 | if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1) {
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[821] | 328 | bb_error_msg_and_die("getsockname");
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| 329 | }
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| 330 | src = saddr.sin_addr;
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| 331 | }
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| 332 | close(probe_fd);
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[1770] | 333 | }
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[821] | 334 |
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| 335 | me.sll_family = AF_PACKET;
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| 336 | me.sll_ifindex = ifindex;
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| 337 | me.sll_protocol = htons(ETH_P_ARP);
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[1770] | 338 | xbind(sock, (struct sockaddr *) &me, sizeof(me));
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[821] | 339 |
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| 340 | {
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| 341 | socklen_t alen = sizeof(me);
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| 342 |
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[1770] | 343 | if (getsockname(sock, (struct sockaddr *) &me, &alen) == -1) {
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[821] | 344 | bb_error_msg_and_die("getsockname");
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| 345 | }
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| 346 | }
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| 347 | if (me.sll_halen == 0) {
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[1770] | 348 | bb_error_msg("interface \"%s\" is not ARPable (no ll address)", device);
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| 349 | return (option_mask32 & DAD ? 0 : 2);
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[821] | 350 | }
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| 351 | he = me;
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| 352 | memset(he.sll_addr, -1, he.sll_halen);
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| 353 |
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[1770] | 354 | if (!(option_mask32 & QUIET)) {
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[821] | 355 | printf("ARPING to %s from %s via %s\n",
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| 356 | inet_ntoa(dst), inet_ntoa(src),
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| 357 | device ? device : "unknown");
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| 358 | }
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| 359 |
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[1770] | 360 | if (!src.s_addr && !(option_mask32 & DAD)) {
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[821] | 361 | bb_error_msg_and_die("no src address in the non-DAD mode");
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| 362 | }
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| 363 |
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| 364 | {
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| 365 | struct sigaction sa;
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| 366 |
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| 367 | memset(&sa, 0, sizeof(sa));
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| 368 | sa.sa_flags = SA_RESTART;
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| 369 |
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| 370 | sa.sa_handler = (void (*)(int)) finish;
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| 371 | sigaction(SIGINT, &sa, NULL);
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| 372 |
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| 373 | sa.sa_handler = (void (*)(int)) catcher;
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| 374 | sigaction(SIGALRM, &sa, NULL);
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| 375 | }
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| 376 |
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| 377 | catcher();
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| 378 |
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[1770] | 379 | packet = xmalloc(4096);
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[821] | 380 | while (1) {
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| 381 | sigset_t sset, osset;
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| 382 | struct sockaddr_ll from;
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| 383 | socklen_t alen = sizeof(from);
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| 384 | int cc;
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| 385 |
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[1770] | 386 | cc = recvfrom(sock, packet, 4096, 0, (struct sockaddr *) &from, &alen);
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| 387 | if (cc < 0) {
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| 388 | bb_perror_msg("recvfrom");
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[821] | 389 | continue;
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| 390 | }
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| 391 | sigemptyset(&sset);
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| 392 | sigaddset(&sset, SIGALRM);
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| 393 | sigaddset(&sset, SIGINT);
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| 394 | sigprocmask(SIG_BLOCK, &sset, &osset);
|
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| 395 | recv_pack(packet, cc, &from);
|
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| 396 | sigprocmask(SIG_SETMASK, &osset, NULL);
|
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| 397 | }
|
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| 398 | }
|
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