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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16 | #include "libbb.h"
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17 |
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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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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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25 | static unsigned last;
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26 |
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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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35 | };
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36 |
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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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45 |
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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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49 | {
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50 | int err;
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51 | unsigned now;
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52 | unsigned char buf[256];
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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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61 | ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
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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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69 | if (option_mask32 & ADVERT)
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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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78 | now = MONOTONIC_US();
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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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83 | if (!(option_mask32 & UNICASTING))
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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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89 | static void finish(void) ATTRIBUTE_NORETURN;
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90 | static void finish(void)
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91 | {
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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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96 | sent, brd_sent,
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97 | received, (received == 1) ? "ies" : "y",
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98 | req_recv, brd_recv);
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99 | }
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100 | if (option_mask32 & DAD)
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101 | exit(!!received);
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102 | if (option_mask32 & UNSOLICITED)
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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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109 | static unsigned start;
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110 |
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111 | unsigned now;
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112 |
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113 | now = MONOTONIC_US();
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114 | if (start == 0)
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115 | start = now;
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116 |
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117 | if (count == 0 || (timeout_us && (now - start) > (timeout_us + 500000)))
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118 | finish();
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119 |
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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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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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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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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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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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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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162 | if (!(option_mask32 & DAD)) {
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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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190 | if (!(option_mask32 & QUIET)) {
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191 | int s_printed = 0;
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192 |
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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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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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206 | ether_ntoa((struct ether_addr *) p + ah->ar_hln + 4));
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207 | }
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208 |
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209 | if (last) {
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210 | printf(" %u.%03ums\n", last / 1000, last % 1000);
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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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221 | if (option_mask32 & QUIT_ON_REPLY)
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222 | finish();
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223 | if (!(option_mask32 & BCAST_ONLY)) {
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224 | memcpy(he.sll_addr, p, me.sll_halen);
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225 | option_mask32 |= UNICASTING;
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226 | }
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227 | return 1;
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228 | }
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229 |
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230 | int arping_main(int argc, char **argv);
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231 | int arping_main(int argc, char **argv)
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232 | {
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233 | const char *device = "eth0";
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234 | int ifindex;
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235 | char *source = NULL;
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236 | char *target;
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237 | unsigned char *packet;
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238 |
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239 | sock = xsocket(PF_PACKET, SOCK_DGRAM, 0);
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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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245 | unsigned opt;
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246 | char *str_count, *str_timeout;
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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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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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262 | }
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263 | //if (opt & 0x200) /* -s: source */
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264 | option_mask32 &= 0x3f; /* set respective flags */
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265 | }
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266 |
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267 | target = argv[optind];
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268 |
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269 | xfunc_error_retval = 2;
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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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276 | ioctl_or_perror_and_die(sock, SIOCGIFINDEX, &ifr, "interface %s not found", device);
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277 | ifindex = ifr.ifr_ifindex;
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278 |
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279 | xioctl(sock, SIOCGIFFLAGS, (char *) &ifr);
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280 |
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281 | if (!(ifr.ifr_flags & IFF_UP)) {
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282 | bb_error_msg_and_die("interface %s is down", device);
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283 | }
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284 | if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
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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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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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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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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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302 | if (!(option_mask32 & DAD) && (option_mask32 & UNSOLICITED) && src.s_addr == 0)
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303 | src = dst;
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304 |
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305 | if (!(option_mask32 & DAD) || src.s_addr) {
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306 | struct sockaddr_in saddr;
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307 | int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
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308 |
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309 | if (device) {
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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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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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317 | xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
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318 | } else if (!(option_mask32 & DAD)) {
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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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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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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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333 | }
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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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338 | xbind(sock, (struct sockaddr *) &me, sizeof(me));
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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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343 | if (getsockname(sock, (struct sockaddr *) &me, &alen) == -1) {
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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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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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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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354 | if (!(option_mask32 & QUIET)) {
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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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360 | if (!src.s_addr && !(option_mask32 & DAD)) {
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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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379 | packet = xmalloc(4096);
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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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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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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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