[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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[3621] | 33 | //usage: "\n -l x.x.0.0 Use this range instead of 169.254"
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[3232] | 34 | //usage: "\n -v Verbose"
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| 35 | //usage: "\n"
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[3621] | 36 | //usage: "\n$LOGGING=none Suppress logging"
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| 37 | //usage: "\n$LOGGING=syslog Log to syslog"
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| 38 | //usage: "\n"
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[3232] | 39 | //usage: "\nWith no -q, runs continuously monitoring for ARP conflicts,"
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| 40 | //usage: "\nexits only on I/O errors (link down etc)"
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| 41 |
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| 42 | #include "libbb.h"
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[3621] | 43 | #include "common_bufsiz.h"
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[821] | 44 | #include <netinet/ether.h>
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| 45 | #include <net/if.h>
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| 46 | #include <net/if_arp.h>
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| 47 | #include <linux/sockios.h>
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| 48 |
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[2725] | 49 | #include <syslog.h>
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[821] | 50 |
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[1765] | 51 | /* We don't need more than 32 bits of the counter */
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| 52 | #define MONOTONIC_US() ((unsigned)monotonic_us())
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| 53 |
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[821] | 54 | struct arp_packet {
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[2725] | 55 | struct ether_header eth;
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[902] | 56 | struct ether_arp arp;
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[2725] | 57 | } PACKED;
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[821] | 58 |
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| 59 | enum {
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[3621] | 60 | /* 0-1 seconds before sending 1st probe */
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[821] | 61 | PROBE_WAIT = 1,
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[3621] | 62 | /* 1-2 seconds between probes */
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[821] | 63 | PROBE_MIN = 1,
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| 64 | PROBE_MAX = 2,
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[3621] | 65 | PROBE_NUM = 3, /* total probes to send */
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| 66 | ANNOUNCE_INTERVAL = 2, /* 2 seconds between announces */
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| 67 | ANNOUNCE_NUM = 3, /* announces to send */
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| 68 | /* if probe/announce sees a conflict, multiply RANDOM(NUM_CONFLICT) by... */
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| 69 | CONFLICT_MULTIPLIER = 2,
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| 70 | /* if we monitor and see a conflict, how long is defend state? */
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| 71 | DEFEND_INTERVAL = 10,
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[821] | 72 | };
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| 73 |
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[902] | 74 | /* States during the configuration process. */
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| 75 | enum {
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| 76 | PROBE = 0,
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| 77 | ANNOUNCE,
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| 78 | MONITOR,
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| 79 | DEFEND
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| 80 | };
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[821] | 81 |
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[2725] | 82 | #define VDBG(...) do { } while (0)
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[821] | 83 |
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[2725] | 84 |
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| 85 | enum {
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| 86 | sock_fd = 3
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| 87 | };
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| 88 |
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| 89 | struct globals {
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[3621] | 90 | struct sockaddr iface_sockaddr;
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| 91 | struct ether_addr our_ethaddr;
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| 92 | uint32_t localnet_ip;
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[2725] | 93 | } FIX_ALIASING;
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[3621] | 94 | #define G (*(struct globals*)bb_common_bufsiz1)
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| 95 | #define INIT_G() do { setup_common_bufsiz(); } while (0)
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[2725] | 96 |
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| 97 |
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[821] | 98 | /**
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| 99 | * Pick a random link local IP address on 169.254/16, except that
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| 100 | * the first and last 256 addresses are reserved.
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| 101 | */
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[3621] | 102 | static uint32_t pick_nip(void)
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[821] | 103 | {
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[1765] | 104 | unsigned tmp;
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[821] | 105 |
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| 106 | do {
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[1765] | 107 | tmp = rand() & IN_CLASSB_HOST;
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[821] | 108 | } while (tmp > (IN_CLASSB_HOST - 0x0200));
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[3621] | 109 | return htonl((G.localnet_ip + 0x0100) + tmp);
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[821] | 110 | }
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| 111 |
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[3621] | 112 | static const char *nip_to_a(uint32_t nip)
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| 113 | {
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| 114 | struct in_addr in;
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| 115 | in.s_addr = nip;
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| 116 | return inet_ntoa(in);
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| 117 | }
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| 118 |
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[821] | 119 | /**
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| 120 | * Broadcast an ARP packet.
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| 121 | */
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[3621] | 122 | static void send_arp_request(
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[2725] | 123 | /* int op, - always ARPOP_REQUEST */
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[3621] | 124 | /* const struct ether_addr *source_eth, - always &G.our_ethaddr */
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| 125 | uint32_t source_nip,
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| 126 | const struct ether_addr *target_eth, uint32_t target_nip)
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[821] | 127 | {
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[2725] | 128 | enum { op = ARPOP_REQUEST };
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[3621] | 129 | #define source_eth (&G.our_ethaddr)
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[2725] | 130 |
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[821] | 131 | struct arp_packet p;
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[902] | 132 | memset(&p, 0, sizeof(p));
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[821] | 133 |
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| 134 | // ether header
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[2725] | 135 | p.eth.ether_type = htons(ETHERTYPE_ARP);
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| 136 | memcpy(p.eth.ether_shost, source_eth, ETH_ALEN);
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| 137 | memset(p.eth.ether_dhost, 0xff, ETH_ALEN);
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[821] | 138 |
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| 139 | // arp request
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[902] | 140 | p.arp.arp_hrd = htons(ARPHRD_ETHER);
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| 141 | p.arp.arp_pro = htons(ETHERTYPE_IP);
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| 142 | p.arp.arp_hln = ETH_ALEN;
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| 143 | p.arp.arp_pln = 4;
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| 144 | p.arp.arp_op = htons(op);
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[2725] | 145 | memcpy(&p.arp.arp_sha, source_eth, ETH_ALEN);
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[3621] | 146 | memcpy(&p.arp.arp_spa, &source_nip, 4);
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[2725] | 147 | memcpy(&p.arp.arp_tha, target_eth, ETH_ALEN);
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[3621] | 148 | memcpy(&p.arp.arp_tpa, &target_nip, 4);
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[821] | 149 |
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| 150 | // send it
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[3621] | 151 | // Even though sock_fd is already bound to G.iface_sockaddr, just send()
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[2725] | 152 | // won't work, because "socket is not connected"
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| 153 | // (and connect() won't fix that, "operation not supported").
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[3621] | 154 | // Thus we sendto() to G.iface_sockaddr. I wonder which sockaddr
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[2725] | 155 | // (from bind() or from sendto()?) kernel actually uses
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| 156 | // to determine iface to emit the packet from...
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[3621] | 157 | xsendto(sock_fd, &p, sizeof(p), &G.iface_sockaddr, sizeof(G.iface_sockaddr));
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[2725] | 158 | #undef source_eth
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[821] | 159 | }
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| 160 |
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| 161 | /**
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[2725] | 162 | * Run a script.
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| 163 | * argv[0]:intf argv[1]:script_name argv[2]:junk argv[3]:NULL
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[821] | 164 | */
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[3621] | 165 | static int run(char *argv[3], const char *param, uint32_t nip)
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[821] | 166 | {
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[1765] | 167 | int status;
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[3621] | 168 | const char *addr = addr; /* for gcc */
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[2725] | 169 | const char *fmt = "%s %s %s" + 3;
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[821] | 170 |
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[2725] | 171 | argv[2] = (char*)param;
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[821] | 172 |
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[2725] | 173 | VDBG("%s run %s %s\n", argv[0], argv[1], argv[2]);
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| 174 |
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[3621] | 175 | if (nip != 0) {
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| 176 | addr = nip_to_a(nip);
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[2725] | 177 | xsetenv("ip", addr);
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| 178 | fmt -= 3;
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[1765] | 179 | }
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[3621] | 180 | bb_error_msg(fmt, argv[2], argv[0], addr);
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[821] | 181 |
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[2725] | 182 | status = spawn_and_wait(argv + 1);
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[1765] | 183 | if (status < 0) {
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[2725] | 184 | bb_perror_msg("%s %s %s" + 3, argv[2], argv[0]);
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[1765] | 185 | return -errno;
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[821] | 186 | }
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[1765] | 187 | if (status != 0)
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[2725] | 188 | bb_error_msg("script %s %s failed, exitcode=%d", argv[1], argv[2], status & 0xff);
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[821] | 189 | return status;
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| 190 | }
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| 191 |
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| 192 | /**
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| 193 | * Return milliseconds of random delay, up to "secs" seconds.
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| 194 | */
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[2725] | 195 | static ALWAYS_INLINE unsigned random_delay_ms(unsigned secs)
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[821] | 196 | {
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[3621] | 197 | return (unsigned)rand() % (secs * 1000);
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[821] | 198 | }
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| 199 |
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| 200 | /**
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| 201 | * main program
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| 202 | */
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[2725] | 203 | int zcip_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
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| 204 | int zcip_main(int argc UNUSED_PARAM, char **argv)
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[821] | 205 | {
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[3621] | 206 | char *r_opt;
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| 207 | const char *l_opt = "169.254.0.0";
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[2725] | 208 | int state;
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[3621] | 209 | int nsent;
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[1765] | 210 | unsigned opts;
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[821] | 211 |
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[3621] | 212 | // Ugly trick, but I want these zeroed in one go
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[1765] | 213 | struct {
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[3621] | 214 | const struct ether_addr null_ethaddr;
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[1765] | 215 | struct ifreq ifr;
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[3621] | 216 | uint32_t chosen_nip;
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| 217 | int conflicts;
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| 218 | int timeout_ms; // must be signed
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[1765] | 219 | int verbose;
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| 220 | } L;
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[3621] | 221 | #define null_ethaddr (L.null_ethaddr)
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| 222 | #define ifr (L.ifr )
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| 223 | #define chosen_nip (L.chosen_nip )
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| 224 | #define conflicts (L.conflicts )
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| 225 | #define timeout_ms (L.timeout_ms )
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| 226 | #define verbose (L.verbose )
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[1765] | 227 |
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| 228 | memset(&L, 0, sizeof(L));
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[3232] | 229 | INIT_G();
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[1765] | 230 |
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| 231 | #define FOREGROUND (opts & 1)
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| 232 | #define QUIT (opts & 2)
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[3621] | 233 | // Parse commandline: prog [options] ifname script
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[1765] | 234 | // exactly 2 args; -v accumulates and implies -f
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| 235 | opt_complementary = "=2:vv:vf";
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[3621] | 236 | opts = getopt32(argv, "fqr:l:v", &r_opt, &l_opt, &verbose);
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[2725] | 237 | #if !BB_MMU
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| 238 | // on NOMMU reexec early (or else we will rerun things twice)
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| 239 | if (!FOREGROUND)
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| 240 | bb_daemonize_or_rexec(0 /*was: DAEMON_CHDIR_ROOT*/, argv);
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| 241 | #endif
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[3621] | 242 | // Open an ARP socket
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[2725] | 243 | // (need to do it before openlog to prevent openlog from taking
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| 244 | // fd 3 (sock_fd==3))
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| 245 | xmove_fd(xsocket(AF_PACKET, SOCK_PACKET, htons(ETH_P_ARP)), sock_fd);
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[1765] | 246 | if (!FOREGROUND) {
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[2725] | 247 | // do it before all bb_xx_msg calls
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[1765] | 248 | openlog(applet_name, 0, LOG_DAEMON);
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| 249 | logmode |= LOGMODE_SYSLOG;
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| 250 | }
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[3621] | 251 | bb_logenv_override();
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| 252 |
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| 253 | { // -l n.n.n.n
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| 254 | struct in_addr net;
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| 255 | if (inet_aton(l_opt, &net) == 0
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| 256 | || (net.s_addr & htonl(IN_CLASSB_NET)) != net.s_addr
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| 257 | ) {
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| 258 | bb_error_msg_and_die("invalid network address");
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| 259 | }
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| 260 | G.localnet_ip = ntohl(net.s_addr);
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| 261 | }
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[1765] | 262 | if (opts & 4) { // -r n.n.n.n
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[3621] | 263 | struct in_addr ip;
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[1765] | 264 | if (inet_aton(r_opt, &ip) == 0
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[3621] | 265 | || (ntohl(ip.s_addr) & IN_CLASSB_NET) != G.localnet_ip
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[1765] | 266 | ) {
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| 267 | bb_error_msg_and_die("invalid link address");
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[821] | 268 | }
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[3621] | 269 | chosen_nip = ip.s_addr;
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[821] | 270 | }
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[2725] | 271 | argv += optind - 1;
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[821] | 272 |
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[2725] | 273 | /* Now: argv[0]:junk argv[1]:intf argv[2]:script argv[3]:NULL */
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| 274 | /* We need to make space for script argument: */
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| 275 | argv[0] = argv[1];
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| 276 | argv[1] = argv[2];
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| 277 | /* Now: argv[0]:intf argv[1]:script argv[2]:junk argv[3]:NULL */
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| 278 | #define argv_intf (argv[0])
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[1765] | 279 |
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[2725] | 280 | xsetenv("interface", argv_intf);
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| 281 |
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[3621] | 282 | // Initialize the interface (modprobe, ifup, etc)
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| 283 | if (run(argv, "init", 0))
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[821] | 284 | return EXIT_FAILURE;
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| 285 |
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[3621] | 286 | // Initialize G.iface_sockaddr
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| 287 | // G.iface_sockaddr is: { u16 sa_family; u8 sa_data[14]; }
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| 288 | //memset(&G.iface_sockaddr, 0, sizeof(G.iface_sockaddr));
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[2725] | 289 | //TODO: are we leaving sa_family == 0 (AF_UNSPEC)?!
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[3621] | 290 | safe_strncpy(G.iface_sockaddr.sa_data, argv_intf, sizeof(G.iface_sockaddr.sa_data));
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[821] | 291 |
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[3621] | 292 | // Bind to the interface's ARP socket
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| 293 | xbind(sock_fd, &G.iface_sockaddr, sizeof(G.iface_sockaddr));
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[821] | 294 |
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[3621] | 295 | // Get the interface's ethernet address
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[1765] | 296 | //memset(&ifr, 0, sizeof(ifr));
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[2725] | 297 | strncpy_IFNAMSIZ(ifr.ifr_name, argv_intf);
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| 298 | xioctl(sock_fd, SIOCGIFHWADDR, &ifr);
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[3621] | 299 | memcpy(&G.our_ethaddr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
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[821] | 300 |
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[3621] | 301 | // Start with some stable ip address, either a function of
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[1765] | 302 | // the hardware address or else the last address we used.
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[2725] | 303 | // we are taking low-order four bytes, as top-order ones
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| 304 | // aren't random enough.
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[1765] | 305 | // NOTE: the sequence of addresses we try changes only
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| 306 | // depending on when we detect conflicts.
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[2725] | 307 | {
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| 308 | uint32_t t;
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[3621] | 309 | move_from_unaligned32(t, ((char *)&G.our_ethaddr + 2));
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[2725] | 310 | srand(t);
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| 311 | }
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[821] | 312 | // FIXME cases to handle:
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| 313 | // - zcip already running!
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| 314 | // - link already has local address... just defend/update
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| 315 |
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[3621] | 316 | // Daemonize now; don't delay system startup
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[1765] | 317 | if (!FOREGROUND) {
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| 318 | #if BB_MMU
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[2725] | 319 | bb_daemonize(0 /*was: DAEMON_CHDIR_ROOT*/);
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[1765] | 320 | #endif
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[3621] | 321 | bb_error_msg("start, interface %s", argv_intf);
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[821] | 322 | }
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| 323 |
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[3621] | 324 | // Run the dynamic address negotiation protocol,
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[821] | 325 | // restarting after address conflicts:
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| 326 | // - start with some address we want to try
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| 327 | // - short random delay
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[2725] | 328 | // - arp probes to see if another host uses it
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[3621] | 329 | // 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff arp who-has 169.254.194.171 tell 0.0.0.0
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[821] | 330 | // - arp announcements that we're claiming it
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[3621] | 331 | // 00:04:e2:64:23:c2 > ff:ff:ff:ff:ff:ff arp who-has 169.254.194.171 (00:04:e2:64:23:c2) tell 169.254.194.171
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[821] | 332 | // - use it
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| 333 | // - defend it, within limits
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[2725] | 334 | // exit if:
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| 335 | // - address is successfully obtained and -q was given:
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| 336 | // run "<script> config", then exit with exitcode 0
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| 337 | // - poll error (when does this happen?)
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| 338 | // - read error (when does this happen?)
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[3621] | 339 | // - sendto error (in send_arp_request()) (when does this happen?)
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[2725] | 340 | // - revents & POLLERR (link down). run "<script> deconfig" first
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[3621] | 341 | if (chosen_nip == 0) {
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| 342 | new_nip_and_PROBE:
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| 343 | chosen_nip = pick_nip();
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| 344 | }
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| 345 | nsent = 0;
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[2725] | 346 | state = PROBE;
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[821] | 347 | while (1) {
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| 348 | struct pollfd fds[1];
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[3621] | 349 | unsigned deadline_us = deadline_us;
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[821] | 350 | struct arp_packet p;
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[3621] | 351 | int ip_conflict;
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| 352 | int n;
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[821] | 353 |
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[2725] | 354 | fds[0].fd = sock_fd;
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[821] | 355 | fds[0].events = POLLIN;
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| 356 | fds[0].revents = 0;
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| 357 |
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[3621] | 358 | // Poll, being ready to adjust current timeout
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[1765] | 359 | if (!timeout_ms) {
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[2725] | 360 | timeout_ms = random_delay_ms(PROBE_WAIT);
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| 361 | // FIXME setsockopt(sock_fd, SO_ATTACH_FILTER, ...) to
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[821] | 362 | // make the kernel filter out all packets except
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| 363 | // ones we'd care about.
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| 364 | }
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[3621] | 365 | if (timeout_ms >= 0) {
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| 366 | // Set deadline_us to the point in time when we timeout
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| 367 | deadline_us = MONOTONIC_US() + timeout_ms * 1000;
|
---|
| 368 | }
|
---|
[821] | 369 |
|
---|
[3621] | 370 | VDBG("...wait %d %s nsent=%u\n",
|
---|
| 371 | timeout_ms, argv_intf, nsent);
|
---|
[1765] | 372 |
|
---|
[3621] | 373 | n = safe_poll(fds, 1, timeout_ms);
|
---|
| 374 | if (n < 0) {
|
---|
[2725] | 375 | //bb_perror_msg("poll"); - done in safe_poll
|
---|
| 376 | return EXIT_FAILURE;
|
---|
[3621] | 377 | }
|
---|
| 378 | if (n == 0) { // timed out?
|
---|
| 379 | VDBG("state:%d\n", state);
|
---|
[902] | 380 | switch (state) {
|
---|
| 381 | case PROBE:
|
---|
[3621] | 382 | // No conflicting ARP packets were seen:
|
---|
| 383 | // we can progress through the states
|
---|
| 384 | if (nsent < PROBE_NUM) {
|
---|
| 385 | nsent++;
|
---|
[1765] | 386 | VDBG("probe/%u %s@%s\n",
|
---|
[3621] | 387 | nsent, argv_intf, nip_to_a(chosen_nip));
|
---|
[1765] | 388 | timeout_ms = PROBE_MIN * 1000;
|
---|
[2725] | 389 | timeout_ms += random_delay_ms(PROBE_MAX - PROBE_MIN);
|
---|
[3621] | 390 | send_arp_request(0, &null_ethaddr, chosen_nip);
|
---|
| 391 | continue;
|
---|
[902] | 392 | }
|
---|
[3621] | 393 | // Switch to announce state
|
---|
| 394 | nsent = 0;
|
---|
[902] | 395 | state = ANNOUNCE;
|
---|
[3621] | 396 | goto send_announce;
|
---|
[902] | 397 | case ANNOUNCE:
|
---|
[3621] | 398 | // No conflicting ARP packets were seen:
|
---|
| 399 | // we can progress through the states
|
---|
| 400 | if (nsent < ANNOUNCE_NUM) {
|
---|
| 401 | send_announce:
|
---|
| 402 | nsent++;
|
---|
[1765] | 403 | VDBG("announce/%u %s@%s\n",
|
---|
[3621] | 404 | nsent, argv_intf, nip_to_a(chosen_nip));
|
---|
[1765] | 405 | timeout_ms = ANNOUNCE_INTERVAL * 1000;
|
---|
[3621] | 406 | send_arp_request(chosen_nip, &G.our_ethaddr, chosen_nip);
|
---|
| 407 | continue;
|
---|
[902] | 408 | }
|
---|
[3621] | 409 | // Switch to monitor state
|
---|
| 410 | // FIXME update filters
|
---|
| 411 | run(argv, "config", chosen_nip);
|
---|
| 412 | // NOTE: all other exit paths should deconfig...
|
---|
| 413 | if (QUIT)
|
---|
| 414 | return EXIT_SUCCESS;
|
---|
| 415 | // fall through: switch to MONITOR
|
---|
| 416 | default:
|
---|
| 417 | // case DEFEND:
|
---|
| 418 | // case MONITOR: (shouldn't happen, MONITOR timeout is infinite)
|
---|
| 419 | // Defend period ended with no ARP replies - we won
|
---|
| 420 | timeout_ms = -1; // never timeout in monitor state
|
---|
[902] | 421 | state = MONITOR;
|
---|
[3621] | 422 | continue;
|
---|
| 423 | }
|
---|
| 424 | }
|
---|
[2725] | 425 |
|
---|
[3621] | 426 | // Packet arrived, or link went down.
|
---|
| 427 | // We need to adjust the timeout in case we didn't receive
|
---|
| 428 | // a conflicting packet.
|
---|
| 429 | if (timeout_ms > 0) {
|
---|
| 430 | unsigned diff = deadline_us - MONOTONIC_US();
|
---|
| 431 | if ((int)(diff) < 0) {
|
---|
| 432 | // Current time is greater than the expected timeout time.
|
---|
| 433 | diff = 0;
|
---|
[821] | 434 | }
|
---|
[3621] | 435 | VDBG("adjusting timeout\n");
|
---|
| 436 | timeout_ms = (diff / 1000) | 1; // never 0
|
---|
| 437 | }
|
---|
[902] | 438 |
|
---|
[3621] | 439 | if ((fds[0].revents & POLLIN) == 0) {
|
---|
| 440 | if (fds[0].revents & POLLERR) {
|
---|
| 441 | // FIXME: links routinely go down;
|
---|
| 442 | // this shouldn't necessarily exit.
|
---|
| 443 | bb_error_msg("iface %s is down", argv_intf);
|
---|
| 444 | if (state >= MONITOR) {
|
---|
| 445 | // Only if we are in MONITOR or DEFEND
|
---|
| 446 | run(argv, "deconfig", chosen_nip);
|
---|
[821] | 447 | }
|
---|
[3621] | 448 | return EXIT_FAILURE;
|
---|
[821] | 449 | }
|
---|
[3621] | 450 | continue;
|
---|
| 451 | }
|
---|
[902] | 452 |
|
---|
[3621] | 453 | // Read ARP packet
|
---|
| 454 | if (safe_read(sock_fd, &p, sizeof(p)) < 0) {
|
---|
| 455 | bb_perror_msg_and_die(bb_msg_read_error);
|
---|
| 456 | }
|
---|
| 457 |
|
---|
| 458 | if (p.eth.ether_type != htons(ETHERTYPE_ARP))
|
---|
| 459 | continue;
|
---|
| 460 | if (p.arp.arp_op != htons(ARPOP_REQUEST)
|
---|
| 461 | && p.arp.arp_op != htons(ARPOP_REPLY)
|
---|
| 462 | ) {
|
---|
| 463 | continue;
|
---|
| 464 | }
|
---|
[902] | 465 | #ifdef DEBUG
|
---|
[3621] | 466 | {
|
---|
| 467 | struct ether_addr *sha = (struct ether_addr *) p.arp.arp_sha;
|
---|
| 468 | struct ether_addr *tha = (struct ether_addr *) p.arp.arp_tha;
|
---|
| 469 | struct in_addr *spa = (struct in_addr *) p.arp.arp_spa;
|
---|
| 470 | struct in_addr *tpa = (struct in_addr *) p.arp.arp_tpa;
|
---|
| 471 | VDBG("source=%s %s\n", ether_ntoa(sha), inet_ntoa(*spa));
|
---|
| 472 | VDBG("target=%s %s\n", ether_ntoa(tha), inet_ntoa(*tpa));
|
---|
| 473 | }
|
---|
[902] | 474 | #endif
|
---|
[3621] | 475 | ip_conflict = 0;
|
---|
| 476 | if (memcmp(&p.arp.arp_sha, &G.our_ethaddr, ETH_ALEN) != 0) {
|
---|
| 477 | if (memcmp(p.arp.arp_spa, &chosen_nip, 4) == 0) {
|
---|
| 478 | // A probe or reply with source_ip == chosen ip
|
---|
| 479 | ip_conflict = 1;
|
---|
[902] | 480 | }
|
---|
[2725] | 481 | if (p.arp.arp_op == htons(ARPOP_REQUEST)
|
---|
[3621] | 482 | && memcmp(p.arp.arp_spa, &const_int_0, 4) == 0
|
---|
| 483 | && memcmp(p.arp.arp_tpa, &chosen_nip, 4) == 0
|
---|
[2725] | 484 | ) {
|
---|
[3621] | 485 | // A probe with source_ip == 0.0.0.0, target_ip == chosen ip:
|
---|
| 486 | // another host trying to claim this ip!
|
---|
| 487 | ip_conflict |= 2;
|
---|
[902] | 488 | }
|
---|
[3621] | 489 | }
|
---|
| 490 | VDBG("state:%d ip_conflict:%d\n", state, ip_conflict);
|
---|
| 491 | if (!ip_conflict)
|
---|
| 492 | continue;
|
---|
[821] | 493 |
|
---|
[3621] | 494 | // Either src or target IP conflict exists
|
---|
| 495 | if (state <= ANNOUNCE) {
|
---|
| 496 | // PROBE or ANNOUNCE
|
---|
| 497 | conflicts++;
|
---|
| 498 | timeout_ms = PROBE_MIN * 1000
|
---|
| 499 | + CONFLICT_MULTIPLIER * random_delay_ms(conflicts);
|
---|
| 500 | goto new_nip_and_PROBE;
|
---|
| 501 | }
|
---|
[902] | 502 |
|
---|
[3621] | 503 | // MONITOR or DEFEND: only src IP conflict is a problem
|
---|
| 504 | if (ip_conflict & 1) {
|
---|
| 505 | if (state == MONITOR) {
|
---|
| 506 | // Src IP conflict, defend with a single ARP probe
|
---|
| 507 | VDBG("monitor conflict - defending\n");
|
---|
| 508 | timeout_ms = DEFEND_INTERVAL * 1000;
|
---|
| 509 | state = DEFEND;
|
---|
| 510 | send_arp_request(chosen_nip, &G.our_ethaddr, chosen_nip);
|
---|
| 511 | continue;
|
---|
| 512 | }
|
---|
| 513 | // state == DEFEND
|
---|
| 514 | // Another src IP conflict, start over
|
---|
| 515 | VDBG("defend conflict - starting over\n");
|
---|
| 516 | run(argv, "deconfig", chosen_nip);
|
---|
| 517 | conflicts = 0;
|
---|
| 518 | timeout_ms = 0;
|
---|
| 519 | goto new_nip_and_PROBE;
|
---|
| 520 | }
|
---|
| 521 | // Note: if we only have a target IP conflict here (ip_conflict & 2),
|
---|
| 522 | // IOW: if we just saw this sort of ARP packet:
|
---|
| 523 | // aa:bb:cc:dd:ee:ff > xx:xx:xx:xx:xx:xx arp who-has <chosen_nip> tell 0.0.0.0
|
---|
| 524 | // we expect _kernel_ to respond to that, because <chosen_nip>
|
---|
| 525 | // is (expected to be) configured on this iface.
|
---|
[2725] | 526 | } // while (1)
|
---|
| 527 | #undef argv_intf
|
---|
[821] | 528 | }
|
---|