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"Robert P. J. Day"63fc1a92006-07-02 19:47:05 +00001/* vi: set sw=4 ts=4: */
Rob Landleyad8071f2005-04-30 03:49:37 +00002/*
3 * RFC3927 ZeroConf IPv4 Link-Local addressing
4 * (see <http://www.zeroconf.org/>)
5 *
6 * Copyright (C) 2003 by Arthur van Hoff (avh@strangeberry.com)
7 * Copyright (C) 2004 by David Brownell
8 *
Bernhard Reutner-Fischer86f5c992006-01-22 22:55:11 +00009 * Licensed under the GPL v2 or later, see the file LICENSE in this tarball.
Rob Landleyad8071f2005-04-30 03:49:37 +000010 */
11
12/*
Rob Landleyad8071f2005-04-30 03:49:37 +000013 * ZCIP just manages the 169.254.*.* addresses. That network is not
14 * routed at the IP level, though various proxies or bridges can
15 * certainly be used. Its naming is built over multicast DNS.
16 */
17
Denis Vlasenko87d80dc2006-09-03 12:20:36 +000018//#define DEBUG
Rob Landleye3752e52005-05-03 03:28:55 +000019
20// TODO:
21// - more real-world usage/testing, especially daemon mode
22// - kernel packet filters to reduce scheduling noise
23// - avoid silent script failures, especially under load...
24// - link status monitoring (restart on link-up; stop on link-down)
25
Rob Landley53433b32006-06-22 22:28:29 +000026#include "busybox.h"
Rob Landleyad8071f2005-04-30 03:49:37 +000027#include <errno.h>
Rob Landleyad8071f2005-04-30 03:49:37 +000028#include <string.h>
29#include <syslog.h>
30#include <poll.h>
31#include <time.h>
Rob Landleyad8071f2005-04-30 03:49:37 +000032
Rob Landleyad8071f2005-04-30 03:49:37 +000033#include <sys/wait.h>
Rob Landleyad8071f2005-04-30 03:49:37 +000034
Rob Landleyad8071f2005-04-30 03:49:37 +000035#include <netinet/ether.h>
36#include <net/ethernet.h>
37#include <net/if.h>
38#include <net/if_arp.h>
39
40#include <linux/if_packet.h>
41#include <linux/sockios.h>
Rob Landleye3752e52005-05-03 03:28:55 +000042
Rob Landleyad8071f2005-04-30 03:49:37 +000043
Bernhard Reutner-Fischerec351c32005-12-13 10:28:25 +000044struct arp_packet {
Rob Landleyad8071f2005-04-30 03:49:37 +000045 struct ether_header hdr;
Denis Vlasenko87d80dc2006-09-03 12:20:36 +000046 struct ether_arp arp;
Bernhard Reutner-Fischer86f5c992006-01-22 22:55:11 +000047} ATTRIBUTE_PACKED;
Rob Landleyad8071f2005-04-30 03:49:37 +000048
Rob Landleybc68cd12006-03-10 19:22:06 +000049enum {
Rob Landleyad8071f2005-04-30 03:49:37 +000050/* 169.254.0.0 */
Rob Landleybc68cd12006-03-10 19:22:06 +000051 LINKLOCAL_ADDR = 0xa9fe0000,
Rob Landleyad8071f2005-04-30 03:49:37 +000052
53/* protocol timeout parameters, specified in seconds */
Rob Landleybc68cd12006-03-10 19:22:06 +000054 PROBE_WAIT = 1,
55 PROBE_MIN = 1,
56 PROBE_MAX = 2,
57 PROBE_NUM = 3,
58 MAX_CONFLICTS = 10,
59 RATE_LIMIT_INTERVAL = 60,
60 ANNOUNCE_WAIT = 2,
61 ANNOUNCE_NUM = 2,
62 ANNOUNCE_INTERVAL = 2,
63 DEFEND_INTERVAL = 10
64};
Rob Landleyad8071f2005-04-30 03:49:37 +000065
Denis Vlasenko87d80dc2006-09-03 12:20:36 +000066/* States during the configuration process. */
67enum {
68 PROBE = 0,
69 RATE_LIMIT_PROBE,
70 ANNOUNCE,
71 MONITOR,
72 DEFEND
73};
Rob Landleyad8071f2005-04-30 03:49:37 +000074
Denis Vlasenkoaf906a32006-09-03 12:29:53 +000075#define VDBG(fmt,args...) \
Rob Landleye3752e52005-05-03 03:28:55 +000076 do { } while (0)
Rob Landleye3752e52005-05-03 03:28:55 +000077
Denis Vlasenkoa9abecd2006-09-03 12:28:32 +000078static unsigned long opts;
79#define FOREGROUND (opts & 1)
80#define QUIT (opts & 2)
81
Rob Landleye3752e52005-05-03 03:28:55 +000082/**
Rob Landleyad8071f2005-04-30 03:49:37 +000083 * Pick a random link local IP address on 169.254/16, except that
84 * the first and last 256 addresses are reserved.
85 */
Rob Landley53433b32006-06-22 22:28:29 +000086static void pick(struct in_addr *ip)
Rob Landleyad8071f2005-04-30 03:49:37 +000087{
Denis Vlasenkoaf906a32006-09-03 12:29:53 +000088 unsigned tmp;
Rob Landleyad8071f2005-04-30 03:49:37 +000089
90 /* use cheaper math than lrand48() mod N */
91 do {
92 tmp = (lrand48() >> 16) & IN_CLASSB_HOST;
93 } while (tmp > (IN_CLASSB_HOST - 0x0200));
94 ip->s_addr = htonl((LINKLOCAL_ADDR + 0x0100) + tmp);
95}
96
Denis Vlasenkoaf906a32006-09-03 12:29:53 +000097/* TODO: we need a flag to direct bb_[p]error_msg output to stderr. */
98
Rob Landleye3752e52005-05-03 03:28:55 +000099/**
Rob Landleyad8071f2005-04-30 03:49:37 +0000100 * Broadcast an ARP packet.
101 */
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000102static void arp(int fd, struct sockaddr *saddr, int op,
Rob Landleyad8071f2005-04-30 03:49:37 +0000103 const struct ether_addr *source_addr, struct in_addr source_ip,
104 const struct ether_addr *target_addr, struct in_addr target_ip)
105{
106 struct arp_packet p;
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000107 memset(&p, 0, sizeof(p));
Rob Landleyad8071f2005-04-30 03:49:37 +0000108
Rob Landleye3752e52005-05-03 03:28:55 +0000109 // ether header
Rob Landleyad8071f2005-04-30 03:49:37 +0000110 p.hdr.ether_type = htons(ETHERTYPE_ARP);
111 memcpy(p.hdr.ether_shost, source_addr, ETH_ALEN);
112 memset(p.hdr.ether_dhost, 0xff, ETH_ALEN);
113
Rob Landleye3752e52005-05-03 03:28:55 +0000114 // arp request
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000115 p.arp.arp_hrd = htons(ARPHRD_ETHER);
116 p.arp.arp_pro = htons(ETHERTYPE_IP);
117 p.arp.arp_hln = ETH_ALEN;
118 p.arp.arp_pln = 4;
119 p.arp.arp_op = htons(op);
120 memcpy(&p.arp.arp_sha, source_addr, ETH_ALEN);
121 memcpy(&p.arp.arp_spa, &source_ip, sizeof (p.arp.arp_spa));
122 memcpy(&p.arp.arp_tha, target_addr, ETH_ALEN);
123 memcpy(&p.arp.arp_tpa, &target_ip, sizeof (p.arp.arp_tpa));
Rob Landleyad8071f2005-04-30 03:49:37 +0000124
Rob Landleye3752e52005-05-03 03:28:55 +0000125 // send it
Rob Landleyad8071f2005-04-30 03:49:37 +0000126 if (sendto(fd, &p, sizeof (p), 0, saddr, sizeof (*saddr)) < 0) {
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000127 bb_perror_msg("sendto");
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000128 //return -errno;
Rob Landleyad8071f2005-04-30 03:49:37 +0000129 }
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000130 // Currently all callers ignore errors, that's why returns are
131 // commented out...
132 //return 0;
Rob Landleyad8071f2005-04-30 03:49:37 +0000133}
134
Rob Landleye3752e52005-05-03 03:28:55 +0000135/**
Rob Landleyad8071f2005-04-30 03:49:37 +0000136 * Run a script.
137 */
Rob Landley53433b32006-06-22 22:28:29 +0000138static int run(char *script, char *arg, char *intf, struct in_addr *ip)
Rob Landleyad8071f2005-04-30 03:49:37 +0000139{
140 int pid, status;
141 char *why;
142
Denis Vlasenkoa9abecd2006-09-03 12:28:32 +0000143 if(1) { //always true: if (script != NULL)
Rob Landleye3752e52005-05-03 03:28:55 +0000144 VDBG("%s run %s %s\n", intf, script, arg);
Rob Landleyad8071f2005-04-30 03:49:37 +0000145 if (ip != NULL) {
146 char *addr = inet_ntoa(*ip);
Rob Landleye3752e52005-05-03 03:28:55 +0000147 setenv("ip", addr, 1);
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000148 bb_info_msg("%s %s %s", arg, intf, addr);
Rob Landleyad8071f2005-04-30 03:49:37 +0000149 }
150
151 pid = vfork();
Rob Landleye3752e52005-05-03 03:28:55 +0000152 if (pid < 0) { // error
Rob Landleyad8071f2005-04-30 03:49:37 +0000153 why = "vfork";
154 goto bad;
Rob Landleye3752e52005-05-03 03:28:55 +0000155 } else if (pid == 0) { // child
Rob Landleyad8071f2005-04-30 03:49:37 +0000156 execl(script, script, arg, NULL);
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000157 bb_perror_msg("execl");
Rob Landleye3752e52005-05-03 03:28:55 +0000158 _exit(EXIT_FAILURE);
Tim Rikerc1ef7bd2006-01-25 00:08:53 +0000159 }
Rob Landleyad8071f2005-04-30 03:49:37 +0000160
161 if (waitpid(pid, &status, 0) <= 0) {
162 why = "waitpid";
163 goto bad;
164 }
165 if (WEXITSTATUS(status) != 0) {
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000166 bb_error_msg("script %s failed, exit=%d",
167 script, WEXITSTATUS(status));
Rob Landleyad8071f2005-04-30 03:49:37 +0000168 return -errno;
169 }
170 }
171 return 0;
172bad:
173 status = -errno;
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000174 bb_perror_msg("%s %s, %s", arg, intf, why);
Rob Landleyad8071f2005-04-30 03:49:37 +0000175 return status;
176}
177
Rob Landleye3752e52005-05-03 03:28:55 +0000178
179/**
Rob Landleyad8071f2005-04-30 03:49:37 +0000180 * Return milliseconds of random delay, up to "secs" seconds.
181 */
Rob Landley88621d72006-08-29 19:41:06 +0000182static unsigned ATTRIBUTE_ALWAYS_INLINE ms_rdelay(unsigned secs)
Rob Landleyad8071f2005-04-30 03:49:37 +0000183{
184 return lrand48() % (secs * 1000);
185}
186
Rob Landleye3752e52005-05-03 03:28:55 +0000187/**
Rob Landleyad8071f2005-04-30 03:49:37 +0000188 * main program
189 */
Bernhard Reutner-Fischer38d66152005-10-21 10:43:11 +0000190
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000191/* Used to be auto variables on main() stack, but
192 * most of them were zero-inited. Moving them to bss
193 * is more space-efficient.
194 */
195static const struct in_addr null_ip; // = { 0 };
196static const struct ether_addr null_addr; // = { {0, 0, 0, 0, 0, 0} };
197
198static struct sockaddr saddr; // memset(0);
199static struct in_addr ip; // = { 0 };
200static struct ifreq ifr; //memset(0);
201
202static char *intf; // = NULL;
203static char *script; // = NULL;
204static suseconds_t timeout; // = 0; // milliseconds
205static unsigned conflicts; // = 0;
206static unsigned nprobes; // = 0;
207static unsigned nclaims; // = 0;
208static int ready; // = 0;
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000209static int verbose; // = 0;
210static int state = PROBE;
211
Rob Landleyad8071f2005-04-30 03:49:37 +0000212int zcip_main(int argc, char *argv[])
213{
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000214 struct ether_addr eth_addr;
Rob Landleyad8071f2005-04-30 03:49:37 +0000215 char *why;
Rob Landleyad8071f2005-04-30 03:49:37 +0000216 int fd;
Denis Vlasenko035aae52006-09-03 12:23:56 +0000217
Rob Landleye3752e52005-05-03 03:28:55 +0000218 // parse commandline: prog [options] ifname script
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000219 char *r_opt;
Denis Vlasenko65113e82006-09-03 12:31:59 +0000220 bb_opt_complementally = "vv:vf"; // -v accumulates and implies -f
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000221 opts = bb_getopt_ulflags(argc, argv, "fqr:v", &r_opt, &verbose);
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000222 if (!FOREGROUND) {
223 /* Do it early, before all bb_xx_msg calls */
224 logmode = LOGMODE_SYSLOG;
225 openlog(bb_applet_name, 0, LOG_DAEMON);
226 }
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000227 if (opts & 4) { // -r n.n.n.n
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000228 if (inet_aton(r_opt, &ip) == 0
229 || (ntohl(ip.s_addr) & IN_CLASSB_NET) != LINKLOCAL_ADDR) {
230 bb_error_msg_and_die("invalid link address");
Rob Landleye3752e52005-05-03 03:28:55 +0000231 }
Rob Landleyad8071f2005-04-30 03:49:37 +0000232 }
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000233 argc -= optind;
234 argv += optind;
235 if (argc != 2)
Rob Landley53433b32006-06-22 22:28:29 +0000236 bb_show_usage();
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000237 intf = argv[0];
238 script = argv[1];
239 setenv("interface", intf, 1);
Rob Landleyad8071f2005-04-30 03:49:37 +0000240
Rob Landleye3752e52005-05-03 03:28:55 +0000241 // initialize the interface (modprobe, ifup, etc)
Rob Landleyad8071f2005-04-30 03:49:37 +0000242 if (run(script, "init", intf, NULL) < 0)
243 return EXIT_FAILURE;
244
Rob Landleye3752e52005-05-03 03:28:55 +0000245 // initialize saddr
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000246 //memset(&saddr, 0, sizeof (saddr));
Rob Landley768945b2006-06-25 00:34:52 +0000247 safe_strncpy(saddr.sa_data, intf, sizeof (saddr.sa_data));
Rob Landleyad8071f2005-04-30 03:49:37 +0000248
Rob Landleye3752e52005-05-03 03:28:55 +0000249 // open an ARP socket
Denis Vlasenko035aae52006-09-03 12:23:56 +0000250 fd = xsocket(PF_PACKET, SOCK_PACKET, htons(ETH_P_ARP));
251 // bind to the interface's ARP socket
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000252 xbind(fd, &saddr, sizeof (saddr));
Denis Vlasenko035aae52006-09-03 12:23:56 +0000253
254 // get the interface's ethernet address
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000255 //memset(&ifr, 0, sizeof (ifr));
Denis Vlasenko035aae52006-09-03 12:23:56 +0000256 strncpy(ifr.ifr_name, intf, sizeof (ifr.ifr_name));
257 if (ioctl(fd, SIOCGIFHWADDR, &ifr) < 0) {
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000258 bb_perror_msg_and_die("get ethernet address");
Rob Landleyad8071f2005-04-30 03:49:37 +0000259 }
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000260 memcpy(&eth_addr, &ifr.ifr_hwaddr.sa_data, ETH_ALEN);
Rob Landleyad8071f2005-04-30 03:49:37 +0000261
Denis Vlasenko035aae52006-09-03 12:23:56 +0000262 // start with some stable ip address, either a function of
263 // the hardware address or else the last address we used.
264 // NOTE: the sequence of addresses we try changes only
265 // depending on when we detect conflicts.
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000266 // (SVID 3 bogon: who says that "short" is always 16 bits?)
267 seed48( (unsigned short*)&ifr.ifr_hwaddr.sa_data );
Denis Vlasenko035aae52006-09-03 12:23:56 +0000268 if (ip.s_addr == 0)
269 pick(&ip);
Rob Landleyad8071f2005-04-30 03:49:37 +0000270
Rob Landleye3752e52005-05-03 03:28:55 +0000271 // FIXME cases to handle:
272 // - zcip already running!
273 // - link already has local address... just defend/update
Rob Landleyad8071f2005-04-30 03:49:37 +0000274
Rob Landleye3752e52005-05-03 03:28:55 +0000275 // daemonize now; don't delay system startup
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000276 if (!FOREGROUND) {
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000277 setsid();
278 xdaemon(0, 0);
279 bb_info_msg("start, interface %s", intf);
Rob Landleyad8071f2005-04-30 03:49:37 +0000280 }
281
Rob Landleye3752e52005-05-03 03:28:55 +0000282 // run the dynamic address negotiation protocol,
283 // restarting after address conflicts:
284 // - start with some address we want to try
285 // - short random delay
286 // - arp probes to see if another host else uses it
287 // - arp announcements that we're claiming it
288 // - use it
289 // - defend it, within limits
Rob Landleyad8071f2005-04-30 03:49:37 +0000290 while (1) {
291 struct pollfd fds[1];
292 struct timeval tv1;
293 struct arp_packet p;
294
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000295 int source_ip_conflict = 0;
296 int target_ip_conflict = 0;
297
Rob Landleyad8071f2005-04-30 03:49:37 +0000298 fds[0].fd = fd;
299 fds[0].events = POLLIN;
300 fds[0].revents = 0;
301
Tim Rikerc1ef7bd2006-01-25 00:08:53 +0000302 // poll, being ready to adjust current timeout
Rob Landley00c051e2006-06-30 14:05:19 +0000303 if (!timeout) {
Rob Landleyad8071f2005-04-30 03:49:37 +0000304 timeout = ms_rdelay(PROBE_WAIT);
Rob Landleye3752e52005-05-03 03:28:55 +0000305 // FIXME setsockopt(fd, SO_ATTACH_FILTER, ...) to
306 // make the kernel filter out all packets except
307 // ones we'd care about.
Rob Landleyad8071f2005-04-30 03:49:37 +0000308 }
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000309 // set tv1 to the point in time when we timeout
Rob Landley00c051e2006-06-30 14:05:19 +0000310 gettimeofday(&tv1, NULL);
311 tv1.tv_usec += (timeout % 1000) * 1000;
312 while (tv1.tv_usec > 1000000) {
313 tv1.tv_usec -= 1000000;
314 tv1.tv_sec++;
315 }
316 tv1.tv_sec += timeout / 1000;
317
Rob Landleye3752e52005-05-03 03:28:55 +0000318 VDBG("...wait %ld %s nprobes=%d, nclaims=%d\n",
319 timeout, intf, nprobes, nclaims);
Rob Landleyad8071f2005-04-30 03:49:37 +0000320 switch (poll(fds, 1, timeout)) {
321
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000322 // timeout
Rob Landleyad8071f2005-04-30 03:49:37 +0000323 case 0:
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000324 VDBG("state = %d\n", state);
325 switch (state) {
326 case PROBE:
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000327 // timeouts in the PROBE state mean no conflicting ARP packets
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000328 // have been received, so we can progress through the states
Rob Landleyad8071f2005-04-30 03:49:37 +0000329 if (nprobes < PROBE_NUM) {
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000330 nprobes++;
331 VDBG("probe/%d %s@%s\n",
332 nprobes, intf, inet_ntoa(ip));
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000333 arp(fd, &saddr, ARPOP_REQUEST,
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000334 &eth_addr, null_ip,
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000335 &null_addr, ip);
Rob Landleyad8071f2005-04-30 03:49:37 +0000336 timeout = PROBE_MIN * 1000;
337 timeout += ms_rdelay(PROBE_MAX
338 - PROBE_MIN);
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000339 }
340 else {
341 // Switch to announce state.
342 state = ANNOUNCE;
343 nclaims = 0;
344 VDBG("announce/%d %s@%s\n",
345 nclaims, intf, inet_ntoa(ip));
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000346 arp(fd, &saddr, ARPOP_REQUEST,
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000347 &eth_addr, ip,
348 &eth_addr, ip);
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000349 timeout = ANNOUNCE_INTERVAL * 1000;
350 }
351 break;
352 case RATE_LIMIT_PROBE:
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000353 // timeouts in the RATE_LIMIT_PROBE state mean no conflicting ARP packets
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000354 // have been received, so we can move immediately to the announce state
355 state = ANNOUNCE;
356 nclaims = 0;
Rob Landleye3752e52005-05-03 03:28:55 +0000357 VDBG("announce/%d %s@%s\n",
358 nclaims, intf, inet_ntoa(ip));
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000359 arp(fd, &saddr, ARPOP_REQUEST,
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000360 &eth_addr, ip,
361 &eth_addr, ip);
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000362 timeout = ANNOUNCE_INTERVAL * 1000;
363 break;
364 case ANNOUNCE:
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000365 // timeouts in the ANNOUNCE state mean no conflicting ARP packets
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000366 // have been received, so we can progress through the states
Rob Landleyad8071f2005-04-30 03:49:37 +0000367 if (nclaims < ANNOUNCE_NUM) {
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000368 nclaims++;
369 VDBG("announce/%d %s@%s\n",
370 nclaims, intf, inet_ntoa(ip));
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000371 arp(fd, &saddr, ARPOP_REQUEST,
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000372 &eth_addr, ip,
373 &eth_addr, ip);
Rob Landleyad8071f2005-04-30 03:49:37 +0000374 timeout = ANNOUNCE_INTERVAL * 1000;
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000375 }
376 else {
377 // Switch to monitor state.
378 state = MONITOR;
Rob Landleye3752e52005-05-03 03:28:55 +0000379 // link is ok to use earlier
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000380 // FIXME update filters
Rob Landleyad8071f2005-04-30 03:49:37 +0000381 run(script, "config", intf, &ip);
382 ready = 1;
383 conflicts = 0;
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000384 timeout = -1; // Never timeout in the monitor state.
Rob Landleyad8071f2005-04-30 03:49:37 +0000385
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000386 // NOTE: all other exit paths
Rob Landleye3752e52005-05-03 03:28:55 +0000387 // should deconfig ...
Denis Vlasenko65dbd872006-09-03 12:27:25 +0000388 if (QUIT)
Rob Landleyad8071f2005-04-30 03:49:37 +0000389 return EXIT_SUCCESS;
Rob Landleyad8071f2005-04-30 03:49:37 +0000390 }
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000391 break;
392 case DEFEND:
393 // We won! No ARP replies, so just go back to monitor.
394 state = MONITOR;
395 timeout = -1;
396 conflicts = 0;
397 break;
398 default:
399 // Invalid, should never happen. Restart the whole protocol.
400 state = PROBE;
401 pick(&ip);
402 timeout = 0;
403 nprobes = 0;
404 nclaims = 0;
405 break;
406 } // switch (state)
407 break; // case 0 (timeout)
Rob Landleye3752e52005-05-03 03:28:55 +0000408 // packets arriving
Rob Landleyad8071f2005-04-30 03:49:37 +0000409 case 1:
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000410 // We need to adjust the timeout in case we didn't receive
411 // a conflicting packet.
Rob Landleyad8071f2005-04-30 03:49:37 +0000412 if (timeout > 0) {
413 struct timeval tv2;
Rob Landleye3752e52005-05-03 03:28:55 +0000414
Rob Landleyad8071f2005-04-30 03:49:37 +0000415 gettimeofday(&tv2, NULL);
416 if (timercmp(&tv1, &tv2, <)) {
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000417 // Current time is greater than the expected timeout time.
418 // Should never happen.
419 VDBG("missed an expected timeout\n");
Paul Foxef81ce62006-03-29 23:01:33 +0000420 timeout = 0;
Rob Landleyad8071f2005-04-30 03:49:37 +0000421 } else {
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000422 VDBG("adjusting timeout\n");
Rob Landleyad8071f2005-04-30 03:49:37 +0000423 timersub(&tv1, &tv2, &tv1);
424 timeout = 1000 * tv1.tv_sec
425 + tv1.tv_usec / 1000;
426 }
427 }
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000428
Rob Landleyad8071f2005-04-30 03:49:37 +0000429 if ((fds[0].revents & POLLIN) == 0) {
430 if (fds[0].revents & POLLERR) {
Rob Landleye3752e52005-05-03 03:28:55 +0000431 // FIXME: links routinely go down;
432 // this shouldn't necessarily exit.
Denis Vlasenko65113e82006-09-03 12:31:59 +0000433 bb_error_msg("%s: poll error", intf);
Rob Landleyad8071f2005-04-30 03:49:37 +0000434 if (ready) {
Rob Landleye3752e52005-05-03 03:28:55 +0000435 run(script, "deconfig",
436 intf, &ip);
Rob Landleyad8071f2005-04-30 03:49:37 +0000437 }
438 return EXIT_FAILURE;
439 }
440 continue;
441 }
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000442
Rob Landleye3752e52005-05-03 03:28:55 +0000443 // read ARP packet
Rob Landleyad8071f2005-04-30 03:49:37 +0000444 if (recv(fd, &p, sizeof (p), 0) < 0) {
445 why = "recv";
446 goto bad;
447 }
448 if (p.hdr.ether_type != htons(ETHERTYPE_ARP))
449 continue;
Rob Landleye3752e52005-05-03 03:28:55 +0000450
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000451#ifdef DEBUG
452 {
453 struct ether_addr * sha = (struct ether_addr *) p.arp.arp_sha;
454 struct ether_addr * tha = (struct ether_addr *) p.arp.arp_tha;
455 struct in_addr * spa = (struct in_addr *) p.arp.arp_spa;
456 struct in_addr * tpa = (struct in_addr *) p.arp.arp_tpa;
457 VDBG("%s recv arp type=%d, op=%d,\n",
Rob Landleye3752e52005-05-03 03:28:55 +0000458 intf, ntohs(p.hdr.ether_type),
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000459 ntohs(p.arp.arp_op));
460 VDBG("\tsource=%s %s\n",
461 ether_ntoa(sha),
462 inet_ntoa(*spa));
463 VDBG("\ttarget=%s %s\n",
464 ether_ntoa(tha),
465 inet_ntoa(*tpa));
466 }
467#endif
468 if (p.arp.arp_op != htons(ARPOP_REQUEST)
469 && p.arp.arp_op != htons(ARPOP_REPLY))
Rob Landleyad8071f2005-04-30 03:49:37 +0000470 continue;
471
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000472 if (memcmp(p.arp.arp_spa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000473 memcmp(&eth_addr, &p.arp.arp_sha, ETH_ALEN) != 0) {
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000474 source_ip_conflict = 1;
475 }
476 if (memcmp(p.arp.arp_tpa, &ip.s_addr, sizeof(struct in_addr)) == 0 &&
477 p.arp.arp_op == htons(ARPOP_REQUEST) &&
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000478 memcmp(&eth_addr, &p.arp.arp_tha, ETH_ALEN) != 0) {
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000479 target_ip_conflict = 1;
480 }
Rob Landleyad8071f2005-04-30 03:49:37 +0000481
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000482 VDBG("state = %d, source ip conflict = %d, target ip conflict = %d\n",
483 state, source_ip_conflict, target_ip_conflict);
484 switch (state) {
485 case PROBE:
486 case ANNOUNCE:
487 // When probing or announcing, check for source IP conflicts
488 // and other hosts doing ARP probes (target IP conflicts).
489 if (source_ip_conflict || target_ip_conflict) {
490 conflicts++;
491 if (conflicts >= MAX_CONFLICTS) {
492 VDBG("%s ratelimit\n", intf);
493 timeout = RATE_LIMIT_INTERVAL * 1000;
494 state = RATE_LIMIT_PROBE;
Rob Landleyad8071f2005-04-30 03:49:37 +0000495 }
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000496
497 // restart the whole protocol
498 pick(&ip);
499 timeout = 0;
500 nprobes = 0;
501 nclaims = 0;
502 }
503 break;
504 case MONITOR:
505 // If a conflict, we try to defend with a single ARP probe.
506 if (source_ip_conflict) {
507 VDBG("monitor conflict -- defending\n");
508 state = DEFEND;
509 timeout = DEFEND_INTERVAL * 1000;
Denis Vlasenkoaf906a32006-09-03 12:29:53 +0000510 arp(fd, &saddr,
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000511 ARPOP_REQUEST,
Denis Vlasenko60e3dd62006-09-03 12:26:06 +0000512 &eth_addr, ip,
513 &eth_addr, ip);
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000514 }
515 break;
516 case DEFEND:
517 // Well, we tried. Start over (on conflict).
518 if (source_ip_conflict) {
519 state = PROBE;
520 VDBG("defend conflict -- starting over\n");
Rob Landleyad8071f2005-04-30 03:49:37 +0000521 ready = 0;
522 run(script, "deconfig", intf, &ip);
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000523
524 // restart the whole protocol
525 pick(&ip);
526 timeout = 0;
527 nprobes = 0;
528 nclaims = 0;
Rob Landleyad8071f2005-04-30 03:49:37 +0000529 }
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000530 break;
531 default:
532 // Invalid, should never happen. Restart the whole protocol.
533 VDBG("invalid state -- starting over\n");
534 state = PROBE;
Rob Landleyad8071f2005-04-30 03:49:37 +0000535 pick(&ip);
536 timeout = 0;
537 nprobes = 0;
538 nclaims = 0;
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000539 break;
540 } // switch state
Rob Landleyad8071f2005-04-30 03:49:37 +0000541
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000542 break; // case 1 (packets arriving)
Rob Landleyad8071f2005-04-30 03:49:37 +0000543 default:
544 why = "poll";
545 goto bad;
Denis Vlasenko87d80dc2006-09-03 12:20:36 +0000546 } // switch poll
Rob Landleyad8071f2005-04-30 03:49:37 +0000547 }
548bad:
Denis Vlasenko3538b9a2006-09-06 18:36:50 +0000549 bb_perror_msg("%s, %s", intf, why);
Rob Landleyad8071f2005-04-30 03:49:37 +0000550 return EXIT_FAILURE;
551}