1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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4 | *
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5 | * Author: Alexey Kuznetsov <kuznet@ms2.inr.ac.ru>
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6 | * Busybox port: Nick Fedchik <nick@fedchik.org.ua>
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7 | */
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8 |
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9 | //usage:#define arping_trivial_usage
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10 | //usage: "[-fqbDUA] [-c CNT] [-w TIMEOUT] [-I IFACE] [-s SRC_IP] DST_IP"
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11 | //usage:#define arping_full_usage "\n\n"
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12 | //usage: "Send ARP requests/replies\n"
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13 | //usage: "\n -f Quit on first ARP reply"
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14 | //usage: "\n -q Quiet"
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15 | //usage: "\n -b Keep broadcasting, don't go unicast"
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16 | //usage: "\n -D Exit with 1 if DST_IP replies"
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17 | //usage: "\n -U Unsolicited ARP mode, update your neighbors"
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18 | //usage: "\n -A ARP answer mode, update your neighbors"
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19 | //usage: "\n -c N Stop after sending N ARP requests"
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20 | //usage: "\n -w TIMEOUT Seconds to wait for ARP reply"
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21 | //usage: "\n -I IFACE Interface to use (default eth0)"
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22 | //usage: "\n -s SRC_IP Sender IP address"
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23 | //usage: "\n DST_IP Target IP address"
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24 |
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25 | #include <arpa/inet.h>
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26 | #include <net/if.h>
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27 | #include <netinet/ether.h>
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28 | #include <netpacket/packet.h>
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29 |
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30 | #include "libbb.h"
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31 | #include "common_bufsiz.h"
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32 |
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33 | /* We don't expect to see 1000+ seconds delay, unsigned is enough */
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34 | #define MONOTONIC_US() ((unsigned)monotonic_us())
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35 |
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36 | enum {
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37 | DAD = 1,
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38 | UNSOLICITED = 2,
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39 | ADVERT = 4,
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40 | QUIET = 8,
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41 | QUIT_ON_REPLY = 16,
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42 | BCAST_ONLY = 32,
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43 | UNICASTING = 64
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44 | };
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45 |
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46 | struct globals {
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47 | struct in_addr src;
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48 | struct in_addr dst;
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49 | struct sockaddr_ll me;
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50 | struct sockaddr_ll he;
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51 | int sock_fd;
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52 |
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53 | int count; // = -1;
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54 | unsigned last;
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55 | unsigned timeout_us;
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56 | unsigned start;
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57 |
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58 | unsigned sent;
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59 | unsigned brd_sent;
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60 | unsigned received;
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61 | unsigned brd_recv;
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62 | unsigned req_recv;
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63 | } FIX_ALIASING;
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64 | #define G (*(struct globals*)bb_common_bufsiz1)
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65 | #define src (G.src )
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66 | #define dst (G.dst )
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67 | #define me (G.me )
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68 | #define he (G.he )
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69 | #define sock_fd (G.sock_fd )
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70 | #define count (G.count )
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71 | #define last (G.last )
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72 | #define timeout_us (G.timeout_us)
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73 | #define start (G.start )
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74 | #define sent (G.sent )
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75 | #define brd_sent (G.brd_sent )
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76 | #define received (G.received )
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77 | #define brd_recv (G.brd_recv )
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78 | #define req_recv (G.req_recv )
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79 | #define INIT_G() do { \
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80 | setup_common_bufsiz(); \
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81 | count = -1; \
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82 | } while (0)
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83 |
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84 | // If GNUisms are not available...
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85 | //static void *mempcpy(void *_dst, const void *_src, int n)
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86 | //{
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87 | // memcpy(_dst, _src, n);
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88 | // return (char*)_dst + n;
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89 | //}
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90 |
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91 | static int send_pack(struct in_addr *src_addr,
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92 | struct in_addr *dst_addr, struct sockaddr_ll *ME,
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93 | struct sockaddr_ll *HE)
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94 | {
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95 | int err;
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96 | unsigned char buf[256];
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97 | struct arphdr *ah = (struct arphdr *) buf;
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98 | unsigned char *p = (unsigned char *) (ah + 1);
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99 |
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100 | ah->ar_hrd = htons(ARPHRD_ETHER);
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101 | ah->ar_pro = htons(ETH_P_IP);
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102 | ah->ar_hln = ME->sll_halen;
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103 | ah->ar_pln = 4;
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104 | ah->ar_op = option_mask32 & ADVERT ? htons(ARPOP_REPLY) : htons(ARPOP_REQUEST);
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105 |
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106 | p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
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107 | p = mempcpy(p, src_addr, 4);
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108 |
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109 | if (option_mask32 & ADVERT)
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110 | p = mempcpy(p, &ME->sll_addr, ah->ar_hln);
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111 | else
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112 | p = mempcpy(p, &HE->sll_addr, ah->ar_hln);
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113 |
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114 | p = mempcpy(p, dst_addr, 4);
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115 |
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116 | err = sendto(sock_fd, buf, p - buf, 0, (struct sockaddr *) HE, sizeof(*HE));
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117 | if (err == p - buf) {
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118 | last = MONOTONIC_US();
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119 | sent++;
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120 | if (!(option_mask32 & UNICASTING))
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121 | brd_sent++;
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122 | }
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123 | return err;
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124 | }
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125 |
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126 | static void finish(void) NORETURN;
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127 | static void finish(void)
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128 | {
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129 | if (!(option_mask32 & QUIET)) {
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130 | printf("Sent %u probe(s) (%u broadcast(s))\n"
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131 | "Received %u repl%s"
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132 | " (%u request(s), %u broadcast(s))\n",
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133 | sent, brd_sent,
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134 | received, (received == 1) ? "ies" : "y",
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135 | req_recv, brd_recv);
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136 | }
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137 | if (option_mask32 & DAD)
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138 | exit(!!received);
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139 | if (option_mask32 & UNSOLICITED)
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140 | exit(EXIT_SUCCESS);
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141 | exit(!received);
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142 | }
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143 |
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144 | static void catcher(void)
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145 | {
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146 | unsigned now;
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147 |
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148 | now = MONOTONIC_US();
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149 | if (start == 0)
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150 | start = now;
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151 |
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152 | if (count == 0 || (timeout_us && (now - start) > timeout_us))
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153 | finish();
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154 |
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155 | /* count < 0 means "infinite count" */
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156 | if (count > 0)
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157 | count--;
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158 |
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159 | if (last == 0 || (now - last) > 500000) {
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160 | send_pack(&src, &dst, &me, &he);
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161 | if (count == 0 && (option_mask32 & UNSOLICITED))
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162 | finish();
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163 | }
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164 | alarm(1);
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165 | }
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166 |
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167 | static void recv_pack(unsigned char *buf, int len, struct sockaddr_ll *FROM)
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168 | {
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169 | struct arphdr *ah = (struct arphdr *) buf;
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170 | unsigned char *p = (unsigned char *) (ah + 1);
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171 | struct in_addr src_ip, dst_ip;
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172 | /* moves below assume in_addr is 4 bytes big, ensure that */
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173 | struct BUG_in_addr_must_be_4 {
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174 | char BUG_in_addr_must_be_4[
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175 | sizeof(struct in_addr) == 4 ? 1 : -1
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176 | ];
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177 | char BUG_s_addr_must_be_4[
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178 | sizeof(src_ip.s_addr) == 4 ? 1 : -1
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179 | ];
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180 | };
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181 |
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182 | /* Filter out wild packets */
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183 | if (FROM->sll_pkttype != PACKET_HOST
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184 | && FROM->sll_pkttype != PACKET_BROADCAST
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185 | && FROM->sll_pkttype != PACKET_MULTICAST)
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186 | return;
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187 |
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188 | /* Only these types are recognized */
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189 | if (ah->ar_op != htons(ARPOP_REQUEST) && ah->ar_op != htons(ARPOP_REPLY))
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190 | return;
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191 |
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192 | /* ARPHRD check and this darned FDDI hack here :-( */
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193 | if (ah->ar_hrd != htons(FROM->sll_hatype)
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194 | && (FROM->sll_hatype != ARPHRD_FDDI || ah->ar_hrd != htons(ARPHRD_ETHER)))
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195 | return;
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196 |
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197 | /* Protocol must be IP. */
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198 | if (ah->ar_pro != htons(ETH_P_IP)
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199 | || (ah->ar_pln != 4)
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200 | || (ah->ar_hln != me.sll_halen)
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201 | || (len < (int)(sizeof(*ah) + 2 * (4 + ah->ar_hln))))
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202 | return;
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203 |
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204 | move_from_unaligned32(src_ip.s_addr, p + ah->ar_hln);
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205 | move_from_unaligned32(dst_ip.s_addr, p + ah->ar_hln + 4 + ah->ar_hln);
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206 |
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207 | if (dst.s_addr != src_ip.s_addr)
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208 | return;
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209 | if (!(option_mask32 & DAD)) {
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210 | if ((src.s_addr != dst_ip.s_addr)
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211 | || (memcmp(p + ah->ar_hln + 4, &me.sll_addr, ah->ar_hln)))
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212 | return;
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213 | } else {
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214 | /* DAD packet was:
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215 | src_ip = 0 (or some src)
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216 | src_hw = ME
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217 | dst_ip = tested address
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218 | dst_hw = <unspec>
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219 |
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220 | We fail, if receive request/reply with:
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221 | src_ip = tested_address
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222 | src_hw != ME
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223 | if src_ip in request was not zero, check
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224 | also that it matches to dst_ip, otherwise
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225 | dst_ip/dst_hw do not matter.
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226 | */
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227 | if ((memcmp(p, &me.sll_addr, me.sll_halen) == 0)
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228 | || (src.s_addr && src.s_addr != dst_ip.s_addr))
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229 | return;
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230 | }
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231 | if (!(option_mask32 & QUIET)) {
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232 | int s_printed = 0;
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233 |
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234 | printf("%scast re%s from %s [%02x:%02x:%02x:%02x:%02x:%02x]",
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235 | FROM->sll_pkttype == PACKET_HOST ? "Uni" : "Broad",
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236 | ah->ar_op == htons(ARPOP_REPLY) ? "ply" : "quest",
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237 | inet_ntoa(src_ip),
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238 | p[0], p[1], p[2], p[3], p[4], p[5]
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239 | );
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240 | if (dst_ip.s_addr != src.s_addr) {
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241 | printf("for %s ", inet_ntoa(dst_ip));
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242 | s_printed = 1;
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243 | }
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244 | if (memcmp(p + ah->ar_hln + 4, me.sll_addr, ah->ar_hln)) {
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245 | unsigned char *pp = p + ah->ar_hln + 4;
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246 | if (!s_printed)
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247 | printf("for ");
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248 | printf("[%02x:%02x:%02x:%02x:%02x:%02x]",
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249 | pp[0], pp[1], pp[2], pp[3], pp[4], pp[5]
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250 | );
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251 | }
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252 |
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253 | if (last) {
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254 | unsigned diff = MONOTONIC_US() - last;
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255 | printf(" %u.%03ums\n", diff / 1000, diff % 1000);
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256 | } else {
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257 | puts(" UNSOLICITED?");
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258 | }
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259 | fflush_all();
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260 | }
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261 | received++;
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262 | if (FROM->sll_pkttype != PACKET_HOST)
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263 | brd_recv++;
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264 | if (ah->ar_op == htons(ARPOP_REQUEST))
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265 | req_recv++;
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266 | if (option_mask32 & QUIT_ON_REPLY)
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267 | finish();
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268 | if (!(option_mask32 & BCAST_ONLY)) {
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269 | memcpy(he.sll_addr, p, me.sll_halen);
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270 | option_mask32 |= UNICASTING;
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271 | }
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272 | }
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273 |
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274 | int arping_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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275 | int arping_main(int argc UNUSED_PARAM, char **argv)
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276 | {
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277 | const char *device = "eth0";
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278 | char *source = NULL;
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279 | char *target;
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280 | unsigned char *packet;
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281 | char *err_str;
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282 |
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283 | INIT_G();
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284 |
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285 | sock_fd = xsocket(AF_PACKET, SOCK_DGRAM, 0);
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286 |
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287 | // Drop suid root privileges
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288 | // Need to remove SUID_NEVER from applets.h for this to work
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289 | //xsetuid(getuid());
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290 |
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291 | {
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292 | unsigned opt;
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293 | char *str_timeout;
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294 |
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295 | /* Dad also sets quit_on_reply.
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296 | * Advert also sets unsolicited.
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297 | */
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298 | opt_complementary = "=1:Df:AU:c+";
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299 | opt = getopt32(argv, "DUAqfbc:w:I:s:",
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300 | &count, &str_timeout, &device, &source);
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301 | if (opt & 0x80) /* -w: timeout */
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302 | timeout_us = xatou_range(str_timeout, 0, INT_MAX/2000000) * 1000000 + 500000;
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303 | //if (opt & 0x200) /* -s: source */
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304 | option_mask32 &= 0x3f; /* set respective flags */
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305 | }
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306 |
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307 | target = argv[optind];
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308 | err_str = xasprintf("interface %s %%s", device);
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309 | xfunc_error_retval = 2;
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310 |
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311 | {
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312 | struct ifreq ifr;
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313 |
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314 | memset(&ifr, 0, sizeof(ifr));
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315 | strncpy_IFNAMSIZ(ifr.ifr_name, device);
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316 | /* We use ifr.ifr_name in error msg so that problem
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317 | * with truncated name will be visible */
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318 | ioctl_or_perror_and_die(sock_fd, SIOCGIFINDEX, &ifr, err_str, "not found");
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319 | me.sll_ifindex = ifr.ifr_ifindex;
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320 |
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321 | xioctl(sock_fd, SIOCGIFFLAGS, (char *) &ifr);
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322 |
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323 | if (!(ifr.ifr_flags & IFF_UP)) {
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324 | bb_error_msg_and_die(err_str, "is down");
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325 | }
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326 | if (ifr.ifr_flags & (IFF_NOARP | IFF_LOOPBACK)) {
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327 | bb_error_msg(err_str, "is not ARPable");
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328 | return (option_mask32 & DAD ? 0 : 2);
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329 | }
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330 | }
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331 |
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332 | /* if (!inet_aton(target, &dst)) - not needed */ {
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333 | len_and_sockaddr *lsa;
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334 | lsa = xhost_and_af2sockaddr(target, 0, AF_INET);
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335 | dst = lsa->u.sin.sin_addr;
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336 | if (ENABLE_FEATURE_CLEAN_UP)
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337 | free(lsa);
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338 | }
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339 |
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340 | if (source && !inet_aton(source, &src)) {
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341 | bb_error_msg_and_die("invalid source address %s", source);
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342 | }
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343 |
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344 | if ((option_mask32 & (DAD|UNSOLICITED)) == UNSOLICITED && src.s_addr == 0)
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345 | src = dst;
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346 |
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347 | if (!(option_mask32 & DAD) || src.s_addr) {
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348 | struct sockaddr_in saddr;
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349 | int probe_fd = xsocket(AF_INET, SOCK_DGRAM, 0);
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350 |
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351 | setsockopt_bindtodevice(probe_fd, device);
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352 | memset(&saddr, 0, sizeof(saddr));
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353 | saddr.sin_family = AF_INET;
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354 | if (src.s_addr) {
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355 | /* Check that this is indeed our IP */
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356 | saddr.sin_addr = src;
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357 | xbind(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
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358 | } else { /* !(option_mask32 & DAD) case */
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359 | /* Find IP address on this iface */
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360 | socklen_t alen = sizeof(saddr);
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361 |
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362 | saddr.sin_port = htons(1025);
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363 | saddr.sin_addr = dst;
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364 |
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365 | if (setsockopt_SOL_SOCKET_1(probe_fd, SO_DONTROUTE) != 0)
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366 | bb_perror_msg("setsockopt(%s)", "SO_DONTROUTE");
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367 | xconnect(probe_fd, (struct sockaddr *) &saddr, sizeof(saddr));
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368 | getsockname(probe_fd, (struct sockaddr *) &saddr, &alen);
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369 | //never happens:
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370 | //if (getsockname(probe_fd, (struct sockaddr *) &saddr, &alen) == -1)
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371 | // bb_perror_msg_and_die("getsockname");
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372 | if (saddr.sin_family != AF_INET)
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373 | bb_error_msg_and_die("no IP address configured");
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374 | src = saddr.sin_addr;
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375 | }
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376 | close(probe_fd);
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377 | }
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378 |
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379 | me.sll_family = AF_PACKET;
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380 | //me.sll_ifindex = ifindex; - done before
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381 | me.sll_protocol = htons(ETH_P_ARP);
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382 | xbind(sock_fd, (struct sockaddr *) &me, sizeof(me));
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383 |
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384 | {
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385 | socklen_t alen = sizeof(me);
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386 | getsockname(sock_fd, (struct sockaddr *) &me, &alen);
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387 | //never happens:
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388 | //if (getsockname(sock_fd, (struct sockaddr *) &me, &alen) == -1)
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389 | // bb_perror_msg_and_die("getsockname");
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390 | }
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391 | if (me.sll_halen == 0) {
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392 | bb_error_msg(err_str, "is not ARPable (no ll address)");
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393 | return (option_mask32 & DAD ? 0 : 2);
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394 | }
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395 | he = me;
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396 | memset(he.sll_addr, -1, he.sll_halen);
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397 |
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398 | if (!(option_mask32 & QUIET)) {
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399 | /* inet_ntoa uses static storage, can't use in same printf */
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400 | printf("ARPING to %s", inet_ntoa(dst));
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401 | printf(" from %s via %s\n", inet_ntoa(src), device);
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402 | }
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403 |
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404 | signal_SA_RESTART_empty_mask(SIGINT, (void (*)(int))finish);
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405 | signal_SA_RESTART_empty_mask(SIGALRM, (void (*)(int))catcher);
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406 |
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407 | catcher();
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408 |
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409 | packet = xmalloc(4096);
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410 | while (1) {
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411 | sigset_t sset, osset;
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412 | struct sockaddr_ll from;
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413 | socklen_t alen = sizeof(from);
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414 | int cc;
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415 |
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416 | cc = recvfrom(sock_fd, packet, 4096, 0, (struct sockaddr *) &from, &alen);
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417 | if (cc < 0) {
|
---|
418 | bb_perror_msg("recvfrom");
|
---|
419 | continue;
|
---|
420 | }
|
---|
421 | sigemptyset(&sset);
|
---|
422 | sigaddset(&sset, SIGALRM);
|
---|
423 | sigaddset(&sset, SIGINT);
|
---|
424 | sigprocmask(SIG_BLOCK, &sset, &osset);
|
---|
425 | recv_pack(packet, cc, &from);
|
---|
426 | sigprocmask(SIG_SETMASK, &osset, NULL);
|
---|
427 | }
|
---|
428 | }
|
---|