[1765] | 1 | /* vi: set sw=4 ts=4: */
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[821] | 2 | /*
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| 3 | * RFC3927 ZeroConf IPv4 Link-Local addressing
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| 4 | * (see <http://www.zeroconf.org/>)
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| 5 | *
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| 6 | * Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com)
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| 7 | * Copyright (C) 2004 by David Brownell
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| 8 | *
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[2725] | 9 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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[821] | 10 | */
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| 11 |
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| 12 | /*
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| 13 | * ZCIP just manages the 169.254.*.* addresses. That network is not
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| 14 | * routed at the IP level, though various proxies or bridges can
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| 15 | * certainly be used. Its naming is built over multicast DNS.
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| 16 | */
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| 17 |
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[902] | 18 | //#define DEBUG
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[821] | 19 |
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| 20 | // TODO:
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| 21 | // - more real-world usage/testing, especially daemon mode
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| 22 | // - kernel packet filters to reduce scheduling noise
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| 23 | // - avoid silent script failures, especially under load...
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| 24 | // - link status monitoring (restart on link-up; stop on link-down)
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| 25 |
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[3232] | 26 | //usage:#define zcip_trivial_usage
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| 27 | //usage: "[OPTIONS] IFACE SCRIPT"
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| 28 | //usage:#define zcip_full_usage "\n\n"
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| 29 | //usage: "Manage a ZeroConf IPv4 link-local address\n"
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| 30 | //usage: "\n -f Run in foreground"
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| 31 | //usage: "\n -q Quit after obtaining address"
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| 32 | //usage: "\n -r 169.254.x.x Request this address first"
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| 33 | //usage: "\n -v Verbose"
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| 34 | //usage: "\n"
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| 35 | //usage: "\nWith no -q, runs continuously monitoring for ARP conflicts,"
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| 36 | //usage: "\nexits only on I/O errors (link down etc)"
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| 37 |
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| 38 | #include "libbb.h"
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[821] | 39 | #include <netinet/ether.h>
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| 40 | #include <net/if.h>
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| 41 | #include <net/if_arp.h>
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| 42 | #include <linux/sockios.h>
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| 43 |
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[2725] | 44 | #include <syslog.h>
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[821] | 45 |
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[1765] | 46 | /* We don't need more than 32 bits of the counter */
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| 47 | #define MONOTONIC_US() ((unsigned)monotonic_us())
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| 48 |
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[821] | 49 | struct arp_packet {
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[2725] | 50 | struct ether_header eth;
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[902] | 51 | struct ether_arp arp;
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[2725] | 52 | } PACKED;
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[821] | 53 |
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| 54 | enum {
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| 55 | /* 169.254.0.0 */
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| 56 | LINKLOCAL_ADDR = 0xa9fe0000,
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| 57 |
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| 58 | /* protocol timeout parameters, specified in seconds */
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| 59 | PROBE_WAIT = 1,
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| 60 | PROBE_MIN = 1,
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| 61 | PROBE_MAX = 2,
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| 62 | PROBE_NUM = 3,
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| 63 | MAX_CONFLICTS = 10,
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| 64 | RATE_LIMIT_INTERVAL = 60,
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| 65 | ANNOUNCE_WAIT = 2,
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| 66 | ANNOUNCE_NUM = 2,
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| 67 | ANNOUNCE_INTERVAL = 2,
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| 68 | DEFEND_INTERVAL = 10
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| 69 | };
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| 70 |
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[902] | 71 | /* States during the configuration process. */
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| 72 | enum {
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| 73 | PROBE = 0,
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| 74 | RATE_LIMIT_PROBE,
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| 75 | ANNOUNCE,
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| 76 | MONITOR,
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| 77 | DEFEND
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| 78 | };
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[821] | 79 |
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[2725] | 80 | #define VDBG(...) do { } while (0)
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[821] | 81 |
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[2725] | 82 |
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| 83 | enum {
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| 84 | sock_fd = 3
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| 85 | };
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| 86 |
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| 87 | struct globals {
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| 88 | struct sockaddr saddr;
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| 89 | struct ether_addr eth_addr;
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| 90 | } FIX_ALIASING;
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| 91 | #define G (*(struct globals*)&bb_common_bufsiz1)
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| 92 | #define saddr (G.saddr )
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| 93 | #define eth_addr (G.eth_addr)
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[3232] | 94 | #define INIT_G() do { } while (0)
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[2725] | 95 |
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| 96 |
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[821] | 97 | /**
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| 98 | * Pick a random link local IP address on 169.254/16, except that
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| 99 | * the first and last 256 addresses are reserved.
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| 100 | */
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[2725] | 101 | static uint32_t pick(void)
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[821] | 102 | {
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[1765] | 103 | unsigned tmp;
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[821] | 104 |
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| 105 | do {
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[1765] | 106 | tmp = rand() & IN_CLASSB_HOST;
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[821] | 107 | } while (tmp > (IN_CLASSB_HOST - 0x0200));
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[2725] | 108 | return htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
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[821] | 109 | }
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| 110 |
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| 111 | /**
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| 112 | * Broadcast an ARP packet.
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| 113 | */
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[2725] | 114 | static void arp(
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| 115 | /* int op, - always ARPOP_REQUEST */
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| 116 | /* const struct ether_addr *source_eth, - always ð_addr */
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| 117 | struct in_addr source_ip,
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| 118 | const struct ether_addr *target_eth, struct in_addr target_ip)
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[821] | 119 | {
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[2725] | 120 | enum { op = ARPOP_REQUEST };
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| 121 | #define source_eth (ð_addr)
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| 122 |
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[821] | 123 | struct arp_packet p;
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[902] | 124 | memset(&p, 0, sizeof(p));
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[821] | 125 |
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| 126 | // ether header
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[2725] | 127 | p.eth.ether_type = htons(ETHERTYPE_ARP);
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| 128 | memcpy(p.eth.ether_shost, source_eth, ETH_ALEN);
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| 129 | memset(p.eth.ether_dhost, 0xff, ETH_ALEN);
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[821] | 130 |
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| 131 | // arp request
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[902] | 132 | p.arp.arp_hrd = htons(ARPHRD_ETHER);
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| 133 | p.arp.arp_pro = htons(ETHERTYPE_IP);
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| 134 | p.arp.arp_hln = ETH_ALEN;
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| 135 | p.arp.arp_pln = 4;
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| 136 | p.arp.arp_op = htons(op);
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[2725] | 137 | memcpy(&p.arp.arp_sha, source_eth, ETH_ALEN);
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[1765] | 138 | memcpy(&p.arp.arp_spa, &source_ip, sizeof(p.arp.arp_spa));
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[2725] | 139 | memcpy(&p.arp.arp_tha, target_eth, ETH_ALEN);
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[1765] | 140 | memcpy(&p.arp.arp_tpa, &target_ip, sizeof(p.arp.arp_tpa));
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[821] | 141 |
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| 142 | // send it
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[2725] | 143 | // Even though sock_fd is already bound to saddr, just send()
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| 144 | // won't work, because "socket is not connected"
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| 145 | // (and connect() won't fix that, "operation not supported").
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| 146 | // Thus we sendto() to saddr. I wonder which sockaddr
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| 147 | // (from bind() or from sendto()?) kernel actually uses
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| 148 | // to determine iface to emit the packet from...
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| 149 | xsendto(sock_fd, &p, sizeof(p), &saddr, sizeof(saddr));
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| 150 | #undef source_eth
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[821] | 151 | }
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| 152 |
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| 153 | /**
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[2725] | 154 | * Run a script.
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| 155 | * argv[0]:intf argv[1]:script_name argv[2]:junk argv[3]:NULL
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[821] | 156 | */
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[2725] | 157 | static int run(char *argv[3], const char *param, struct in_addr *ip)
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[821] | 158 | {
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[1765] | 159 | int status;
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[2725] | 160 | char *addr = addr; /* for gcc */
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| 161 | const char *fmt = "%s %s %s" + 3;
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[821] | 162 |
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[2725] | 163 | argv[2] = (char*)param;
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[821] | 164 |
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[2725] | 165 | VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]);
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| 166 |
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[1765] | 167 | if (ip) {
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[2725] | 168 | addr = inet_ntoa(*ip);
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| 169 | xsetenv("ip", addr);
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| 170 | fmt -= 3;
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[1765] | 171 | }
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[2725] | 172 | bb_info_msg(fmt, argv[2], argv[0], addr);
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[821] | 173 |
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[2725] | 174 | status = spawn_and_wait(argv + 1);
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[1765] | 175 | if (status < 0) {
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[2725] | 176 | bb_perror_msg("%s %s %s" + 3, argv[2], argv[0]);
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[1765] | 177 | return -errno;
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[821] | 178 | }
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[1765] | 179 | if (status != 0)
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[2725] | 180 | bb_error_msg("script %s %s failed, exitcode=%d", argv[1], argv[2], status & 0xff);
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[821] | 181 | return status;
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| 182 | }
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| 183 |
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| 184 | /**
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| 185 | * Return milliseconds of random delay, up to "secs" seconds.
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| 186 | */
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[2725] | 187 | static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs)
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[821] | 188 | {
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[1765] | 189 | return rand() % (secs * 1000);
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[821] | 190 | }
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| 191 |
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| 192 | /**
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| 193 | * main program
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| 194 | */
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[2725] | 195 | int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 196 | int zcip_main(int argc UNUSED_PARAM, char **argv)
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[821] | 197 | {
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[2725] | 198 | int state;
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[1765] | 199 | char *r_opt;
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| 200 | unsigned opts;
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[821] | 201 |
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[2725] | 202 | // ugly trick, but I want these zeroed in one go
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[1765] | 203 | struct {
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| 204 | const struct in_addr null_ip;
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| 205 | const struct ether_addr null_addr;
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| 206 | struct in_addr ip;
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| 207 | struct ifreq ifr;
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| 208 | int timeout_ms; /* must be signed */
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| 209 | unsigned conflicts;
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| 210 | unsigned nprobes;
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| 211 | unsigned nclaims;
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| 212 | int ready;
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| 213 | int verbose;
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| 214 | } L;
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| 215 | #define null_ip (L.null_ip )
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| 216 | #define null_addr (L.null_addr )
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| 217 | #define ip (L.ip )
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| 218 | #define ifr (L.ifr )
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| 219 | #define timeout_ms (L.timeout_ms)
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| 220 | #define conflicts (L.conflicts )
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| 221 | #define nprobes (L.nprobes )
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| 222 | #define nclaims (L.nclaims )
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| 223 | #define ready (L.ready )
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| 224 | #define verbose (L.verbose )
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| 225 |
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| 226 | memset(&L, 0, sizeof(L));
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[3232] | 227 | INIT_G();
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[1765] | 228 |
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| 229 | #define FOREGROUND (opts & 1)
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| 230 | #define QUIT (opts & 2)
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[821] | 231 | // parse commandline: prog [options] ifname script
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[1765] | 232 | // exactly 2 args; -v accumulates and implies -f
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| 233 | opt_complementary = "=2:vv:vf";
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| 234 | opts = getopt32(argv, "fqr:v", &r_opt, &verbose);
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[2725] | 235 | #if !BB_MMU
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| 236 | // on NOMMU reexec early (or else we will rerun things twice)
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| 237 | if (!FOREGROUND)
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| 238 | bb_daemonize_or_rexec(0 /*was: DAEMON_CHDIR_ROOT*/, argv);
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| 239 | #endif
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| 240 | // open an ARP socket
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| 241 | // (need to do it before openlog to prevent openlog from taking
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| 242 | // fd 3 (sock_fd==3))
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| 243 | xmove_fd(xsocket(AF_PACKET, SOCK_PACKET, htons(ETH_P_ARP)), sock_fd);
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[1765] | 244 | if (!FOREGROUND) {
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[2725] | 245 | // do it before all bb_xx_msg calls
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[1765] | 246 | openlog(applet_name, 0, LOG_DAEMON);
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| 247 | logmode |= LOGMODE_SYSLOG;
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| 248 | }
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| 249 | if (opts & 4) { // -r n.n.n.n
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| 250 | if (inet_aton(r_opt, &ip) == 0
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| 251 | || (ntohl(ip.s_addr) & IN_CLASSB_NET) != LINKLOCAL_ADDR
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| 252 | ) {
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| 253 | bb_error_msg_and_die("invalid link address");
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[821] | 254 | }
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| 255 | }
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[2725] | 256 | argv += optind - 1;
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[821] | 257 |
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[2725] | 258 | /* Now: argv[0]:junk argv[1]:intf argv[2]:script argv[3]:NULL */
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| 259 | /* We need to make space for script argument: */
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| 260 | argv[0] = argv[1];
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| 261 | argv[1] = argv[2];
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| 262 | /* Now: argv[0]:intf argv[1]:script argv[2]:junk argv[3]:NULL */
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| 263 | #define argv_intf (argv[0])
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[1765] | 264 |
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[2725] | 265 | xsetenv("interface", argv_intf);
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| 266 |
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[821] | 267 | // initialize the interface (modprobe, ifup, etc)
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[2725] | 268 | if (run(argv, "init", NULL))
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[821] | 269 | return EXIT_FAILURE;
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| 270 |
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| 271 | // initialize saddr
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[2725] | 272 | // saddr is: { u16 sa_family; u8 sa_data[14]; }
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[1765] | 273 | //memset(&saddr, 0, sizeof(saddr));
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[2725] | 274 | //TODO: are we leaving sa_family == 0 (AF_UNSPEC)?!
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| 275 | safe_strncpy(saddr.sa_data, argv_intf, sizeof(saddr.sa_data));
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[821] | 276 |
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| 277 | // bind to the interface's ARP socket
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[2725] | 278 | xbind(sock_fd, &saddr, sizeof(saddr));
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[821] | 279 |
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[1765] | 280 | // get the interface's ethernet address
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| 281 | //memset(&ifr, 0, sizeof(ifr));
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[2725] | 282 | strncpy_IFNAMSIZ(ifr.ifr_name, argv_intf);
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| 283 | xioctl(sock_fd, SIOCGIFHWADDR, &ifr);
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[1765] | 284 | memcpy(ð_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
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[821] | 285 |
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[1765] | 286 | // start with some stable ip address, either a function of
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| 287 | // the hardware address or else the last address we used.
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[2725] | 288 | // we are taking low-order four bytes, as top-order ones
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| 289 | // aren't random enough.
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[1765] | 290 | // NOTE: the sequence of addresses we try changes only
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| 291 | // depending on when we detect conflicts.
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[2725] | 292 | {
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| 293 | uint32_t t;
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| 294 | move_from_unaligned32(t, ((char *)ð_addr + 2));
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| 295 | srand(t);
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| 296 | }
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[1765] | 297 | if (ip.s_addr == 0)
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[2725] | 298 | ip.s_addr = pick();
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[821] | 299 |
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| 300 | // FIXME cases to handle:
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| 301 | // - zcip already running!
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| 302 | // - link already has local address... just defend/update
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| 303 |
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| 304 | // daemonize now; don't delay system startup
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[1765] | 305 | if (!FOREGROUND) {
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| 306 | #if BB_MMU
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[2725] | 307 | bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/);
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[1765] | 308 | #endif
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[2725] | 309 | bb_info_msg("start, interface %s", argv_intf);
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[821] | 310 | }
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| 311 |
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| 312 | // run the dynamic address negotiation protocol,
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| 313 | // restarting after address conflicts:
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| 314 | // - start with some address we want to try
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| 315 | // - short random delay
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[2725] | 316 | // - arp probes to see if another host uses it
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[821] | 317 | // - arp announcements that we're claiming it
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| 318 | // - use it
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| 319 | // - defend it, within limits
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[2725] | 320 | // exit if:
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| 321 | // - address is successfully obtained and -q was given:
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| 322 | // run "<script> config", then exit with exitcode 0
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| 323 | // - poll error (when does this happen?)
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| 324 | // - read error (when does this happen?)
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| 325 | // - sendto error (in arp()) (when does this happen?)
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| 326 | // - revents & POLLERR (link down). run "<script> deconfig" first
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| 327 | state = PROBE;
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[821] | 328 | while (1) {
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| 329 | struct pollfd fds[1];
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[1765] | 330 | unsigned deadline_us;
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[821] | 331 | struct arp_packet p;
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[2725] | 332 | int source_ip_conflict;
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| 333 | int target_ip_conflict;
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[821] | 334 |
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[2725] | 335 | fds[0].fd = sock_fd;
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[821] | 336 | fds[0].events = POLLIN;
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| 337 | fds[0].revents = 0;
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| 338 |
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| 339 | // poll, being ready to adjust current timeout
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[1765] | 340 | if (!timeout_ms) {
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[2725] | 341 | timeout_ms = random_delay_ms(PROBE_WAIT);
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| 342 | // FIXME setsockopt(sock_fd, SO_ATTACH_FILTER, ...) to
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[821] | 343 | // make the kernel filter out all packets except
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| 344 | // ones we'd care about.
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| 345 | }
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[1765] | 346 | // set deadline_us to the point in time when we timeout
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| 347 | deadline_us = MONOTONIC_US() + timeout_ms * 1000;
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[821] | 348 |
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[1765] | 349 | VDBG("...wait %d %s nprobes=%u, nclaims=%u\n",
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[2725] | 350 | timeout_ms, argv_intf, nprobes, nclaims);
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[1765] | 351 |
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[2725] | 352 | switch (safe_poll(fds, 1, timeout_ms)) {
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| 353 |
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| 354 | default:
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| 355 | //bb_perror_msg("poll"); - done in safe_poll
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| 356 | return EXIT_FAILURE;
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| 357 |
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[902] | 358 | // timeout
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[821] | 359 | case 0:
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[902] | 360 | VDBG("state = %d\n", state);
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| 361 | switch (state) {
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| 362 | case PROBE:
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[1765] | 363 | // timeouts in the PROBE state mean no conflicting ARP packets
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[902] | 364 | // have been received, so we can progress through the states
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[821] | 365 | if (nprobes < PROBE_NUM) {
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[902] | 366 | nprobes++;
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[1765] | 367 | VDBG("probe/%u %s@%s\n",
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[2725] | 368 | nprobes, argv_intf, inet_ntoa(ip));
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| 369 | arp(/* ARPOP_REQUEST, */
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| 370 | /* ð_addr, */ null_ip,
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[902] | 371 | &null_addr, ip);
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[1765] | 372 | timeout_ms = PROBE_MIN * 1000;
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[2725] | 373 | timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
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[902] | 374 | }
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| 375 | else {
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| 376 | // Switch to announce state.
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| 377 | state = ANNOUNCE;
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| 378 | nclaims = 0;
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[1765] | 379 | VDBG("announce/%u %s@%s\n",
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[2725] | 380 | nclaims, argv_intf, inet_ntoa(ip));
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| 381 | arp(/* ARPOP_REQUEST, */
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| 382 | /* ð_addr, */ ip,
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[1765] | 383 | ð_addr, ip);
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| 384 | timeout_ms = ANNOUNCE_INTERVAL * 1000;
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[902] | 385 | }
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| 386 | break;
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| 387 | case RATE_LIMIT_PROBE:
|
---|
[1765] | 388 | // timeouts in the RATE_LIMIT_PROBE state mean no conflicting ARP packets
|
---|
[902] | 389 | // have been received, so we can move immediately to the announce state
|
---|
| 390 | state = ANNOUNCE;
|
---|
| 391 | nclaims = 0;
|
---|
[1765] | 392 | VDBG("announce/%u %s@%s\n",
|
---|
[2725] | 393 | nclaims, argv_intf, inet_ntoa(ip));
|
---|
| 394 | arp(/* ARPOP_REQUEST, */
|
---|
| 395 | /* ð_addr, */ ip,
|
---|
[1765] | 396 | ð_addr, ip);
|
---|
| 397 | timeout_ms = ANNOUNCE_INTERVAL * 1000;
|
---|
[902] | 398 | break;
|
---|
| 399 | case ANNOUNCE:
|
---|
[1765] | 400 | // timeouts in the ANNOUNCE state mean no conflicting ARP packets
|
---|
[902] | 401 | // have been received, so we can progress through the states
|
---|
[821] | 402 | if (nclaims < ANNOUNCE_NUM) {
|
---|
[902] | 403 | nclaims++;
|
---|
[1765] | 404 | VDBG("announce/%u %s@%s\n",
|
---|
[2725] | 405 | nclaims, argv_intf, inet_ntoa(ip));
|
---|
| 406 | arp(/* ARPOP_REQUEST, */
|
---|
| 407 | /* ð_addr, */ ip,
|
---|
[1765] | 408 | ð_addr, ip);
|
---|
| 409 | timeout_ms = ANNOUNCE_INTERVAL * 1000;
|
---|
[902] | 410 | }
|
---|
| 411 | else {
|
---|
| 412 | // Switch to monitor state.
|
---|
| 413 | state = MONITOR;
|
---|
[821] | 414 | // link is ok to use earlier
|
---|
[902] | 415 | // FIXME update filters
|
---|
[2725] | 416 | run(argv, "config", &ip);
|
---|
[821] | 417 | ready = 1;
|
---|
| 418 | conflicts = 0;
|
---|
[1765] | 419 | timeout_ms = -1; // Never timeout in the monitor state.
|
---|
[821] | 420 |
|
---|
[1765] | 421 | // NOTE: all other exit paths
|
---|
[821] | 422 | // should deconfig ...
|
---|
[1765] | 423 | if (QUIT)
|
---|
[821] | 424 | return EXIT_SUCCESS;
|
---|
| 425 | }
|
---|
[902] | 426 | break;
|
---|
| 427 | case DEFEND:
|
---|
| 428 | // We won! No ARP replies, so just go back to monitor.
|
---|
| 429 | state = MONITOR;
|
---|
[1765] | 430 | timeout_ms = -1;
|
---|
[902] | 431 | conflicts = 0;
|
---|
| 432 | break;
|
---|
| 433 | default:
|
---|
| 434 | // Invalid, should never happen. Restart the whole protocol.
|
---|
| 435 | state = PROBE;
|
---|
[2725] | 436 | ip.s_addr = pick();
|
---|
[1765] | 437 | timeout_ms = 0;
|
---|
[902] | 438 | nprobes = 0;
|
---|
| 439 | nclaims = 0;
|
---|
| 440 | break;
|
---|
| 441 | } // switch (state)
|
---|
| 442 | break; // case 0 (timeout)
|
---|
[2725] | 443 |
|
---|
| 444 | // packets arriving, or link went down
|
---|
[821] | 445 | case 1:
|
---|
[902] | 446 | // We need to adjust the timeout in case we didn't receive
|
---|
| 447 | // a conflicting packet.
|
---|
[1765] | 448 | if (timeout_ms > 0) {
|
---|
| 449 | unsigned diff = deadline_us - MONOTONIC_US();
|
---|
| 450 | if ((int)(diff) < 0) {
|
---|
[902] | 451 | // Current time is greater than the expected timeout time.
|
---|
| 452 | // Should never happen.
|
---|
| 453 | VDBG("missed an expected timeout\n");
|
---|
[1765] | 454 | timeout_ms = 0;
|
---|
[821] | 455 | } else {
|
---|
[902] | 456 | VDBG("adjusting timeout\n");
|
---|
[2725] | 457 | timeout_ms = (diff / 1000) | 1; /* never 0 */
|
---|
[821] | 458 | }
|
---|
| 459 | }
|
---|
[902] | 460 |
|
---|
[821] | 461 | if ((fds[0].revents & POLLIN) == 0) {
|
---|
| 462 | if (fds[0].revents & POLLERR) {
|
---|
| 463 | // FIXME: links routinely go down;
|
---|
| 464 | // this shouldn't necessarily exit.
|
---|
[2725] | 465 | bb_error_msg("iface %s is down", argv_intf);
|
---|
[821] | 466 | if (ready) {
|
---|
[2725] | 467 | run(argv, "deconfig", &ip);
|
---|
[821] | 468 | }
|
---|
| 469 | return EXIT_FAILURE;
|
---|
| 470 | }
|
---|
| 471 | continue;
|
---|
| 472 | }
|
---|
[902] | 473 |
|
---|
[821] | 474 | // read ARP packet
|
---|
[2725] | 475 | if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
|
---|
| 476 | bb_perror_msg_and_die(bb_msg_read_error);
|
---|
[821] | 477 | }
|
---|
[2725] | 478 | if (p.eth.ether_type != htons(ETHERTYPE_ARP))
|
---|
[821] | 479 | continue;
|
---|
[902] | 480 | #ifdef DEBUG
|
---|
| 481 | {
|
---|
[2725] | 482 | struct ether_addr *sha = (struct ether_addr *) p.arp.arp_sha;
|
---|
| 483 | struct ether_addr *tha = (struct ether_addr *) p.arp.arp_tha;
|
---|
| 484 | struct in_addr *spa = (struct in_addr *) p.arp.arp_spa;
|
---|
| 485 | struct in_addr *tpa = (struct in_addr *) p.arp.arp_tpa;
|
---|
[902] | 486 | VDBG("%s recv arp type=%d, op=%d,\n",
|
---|
[2725] | 487 | argv_intf, ntohs(p.eth.ether_type),
|
---|
[902] | 488 | ntohs(p.arp.arp_op));
|
---|
| 489 | VDBG("\tsource=%s %s\n",
|
---|
| 490 | ether_ntoa(sha),
|
---|
| 491 | inet_ntoa(*spa));
|
---|
| 492 | VDBG("\ttarget=%s %s\n",
|
---|
| 493 | ether_ntoa(tha),
|
---|
| 494 | inet_ntoa(*tpa));
|
---|
| 495 | }
|
---|
| 496 | #endif
|
---|
| 497 | if (p.arp.arp_op != htons(ARPOP_REQUEST)
|
---|
[2725] | 498 | && p.arp.arp_op != htons(ARPOP_REPLY))
|
---|
[821] | 499 | continue;
|
---|
| 500 |
|
---|
[2725] | 501 | source_ip_conflict = 0;
|
---|
| 502 | target_ip_conflict = 0;
|
---|
| 503 |
|
---|
| 504 | if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0
|
---|
| 505 | && memcmp(&p.arp.arp_sha, ð_addr, ETH_ALEN) != 0
|
---|
| 506 | ) {
|
---|
[902] | 507 | source_ip_conflict = 1;
|
---|
| 508 | }
|
---|
[2725] | 509 | if (p.arp.arp_op == htons(ARPOP_REQUEST)
|
---|
| 510 | && memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0
|
---|
| 511 | && memcmp(&p.arp.arp_tha, ð_addr, ETH_ALEN) != 0
|
---|
| 512 | ) {
|
---|
[902] | 513 | target_ip_conflict = 1;
|
---|
| 514 | }
|
---|
[821] | 515 |
|
---|
[1765] | 516 | VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n",
|
---|
[902] | 517 | state, source_ip_conflict, target_ip_conflict);
|
---|
| 518 | switch (state) {
|
---|
| 519 | case PROBE:
|
---|
| 520 | case ANNOUNCE:
|
---|
| 521 | // When probing or announcing, check for source IP conflicts
|
---|
| 522 | // and other hosts doing ARP probes (target IP conflicts).
|
---|
| 523 | if (source_ip_conflict || target_ip_conflict) {
|
---|
| 524 | conflicts++;
|
---|
| 525 | if (conflicts >= MAX_CONFLICTS) {
|
---|
[2725] | 526 | VDBG("%s ratelimit\n", argv_intf);
|
---|
[1765] | 527 | timeout_ms = RATE_LIMIT_INTERVAL * 1000;
|
---|
[902] | 528 | state = RATE_LIMIT_PROBE;
|
---|
[821] | 529 | }
|
---|
[902] | 530 |
|
---|
| 531 | // restart the whole protocol
|
---|
[2725] | 532 | ip.s_addr = pick();
|
---|
[1765] | 533 | timeout_ms = 0;
|
---|
[902] | 534 | nprobes = 0;
|
---|
| 535 | nclaims = 0;
|
---|
| 536 | }
|
---|
| 537 | break;
|
---|
| 538 | case MONITOR:
|
---|
| 539 | // If a conflict, we try to defend with a single ARP probe.
|
---|
| 540 | if (source_ip_conflict) {
|
---|
| 541 | VDBG("monitor conflict -- defending\n");
|
---|
| 542 | state = DEFEND;
|
---|
[1765] | 543 | timeout_ms = DEFEND_INTERVAL * 1000;
|
---|
[2725] | 544 | arp(/* ARPOP_REQUEST, */
|
---|
| 545 | /* ð_addr, */ ip,
|
---|
| 546 | ð_addr, ip);
|
---|
[902] | 547 | }
|
---|
| 548 | break;
|
---|
| 549 | case DEFEND:
|
---|
| 550 | // Well, we tried. Start over (on conflict).
|
---|
| 551 | if (source_ip_conflict) {
|
---|
| 552 | state = PROBE;
|
---|
| 553 | VDBG("defend conflict -- starting over\n");
|
---|
[821] | 554 | ready = 0;
|
---|
[2725] | 555 | run(argv, "deconfig", &ip);
|
---|
[902] | 556 |
|
---|
| 557 | // restart the whole protocol
|
---|
[2725] | 558 | ip.s_addr = pick();
|
---|
[1765] | 559 | timeout_ms = 0;
|
---|
[902] | 560 | nprobes = 0;
|
---|
| 561 | nclaims = 0;
|
---|
[821] | 562 | }
|
---|
[902] | 563 | break;
|
---|
| 564 | default:
|
---|
| 565 | // Invalid, should never happen. Restart the whole protocol.
|
---|
| 566 | VDBG("invalid state -- starting over\n");
|
---|
| 567 | state = PROBE;
|
---|
[2725] | 568 | ip.s_addr = pick();
|
---|
[1765] | 569 | timeout_ms = 0;
|
---|
[821] | 570 | nprobes = 0;
|
---|
| 571 | nclaims = 0;
|
---|
[902] | 572 | break;
|
---|
| 573 | } // switch state
|
---|
| 574 | break; // case 1 (packets arriving)
|
---|
| 575 | } // switch poll
|
---|
[2725] | 576 | } // while (1)
|
---|
| 577 | #undef argv_intf
|
---|
[821] | 578 | }
|
---|