4 This file is part of avahi.
6 avahi is free software; you can redistribute it and/or modify it
7 under the terms of the GNU Lesser General Public License as
8 published by the Free Software Foundation; either version 2.1 of the
9 License, or (at your option) any later version.
11 avahi is distributed in the hope that it will be useful, but WITHOUT
12 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
13 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
14 Public License for more details.
16 You should have received a copy of the GNU Lesser General Public
17 License along with avahi; if not, write to the Free Software
18 Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
28 #include <sys/socket.h>
29 #include <netpacket/packet.h>
30 #include <net/ethernet.h>
37 #include <sys/types.h>
38 #include <arpa/inet.h>
39 #include <sys/ioctl.h>
43 #include <avahi-common/malloc.h>
44 #include <avahi-common/timeval.h>
46 #include <libdaemon/dfork.h>
47 #include <libdaemon/dsignal.h>
48 #include <libdaemon/dlog.h>
49 #include <libdaemon/dpid.h>
50 #include <libdaemon/dexec.h>
53 #error "avahi-autoipd is only available on Linux for now"
56 /* An implementation of RFC 3927 */
58 /* Constants from the RFC */
63 #define ANNOUNCE_WAIT 2
64 #define ANNOUNCE_NUM 2
65 #define ANNOUNCE_INTERVAL 2
66 #define MAX_CONFLICTS 10
67 #define RATE_LIMIT_INTERVAL 60
68 #define DEFEND_INTERVAL 10
70 #define IPV4LL_NETWORK 0xA9FE0000L
71 #define IPV4LL_NETMASK 0xFFFF0000L
72 #define IPV4LL_HOSTMASK 0x0000FFFFL
74 #define ETHER_ADDRLEN 6
75 #define ARP_PACKET_SIZE (8+4+4+2*ETHER_ADDRLEN)
81 STATE_WAITING_ANNOUNCE,
88 typedef enum ArpOperation {
93 typedef struct ArpPacketInfo {
94 ArpOperation operation;
96 uint32_t sender_ip_address, target_ip_address;
97 uint8_t sender_hw_address[ETHER_ADDRLEN], target_hw_address[ETHER_ADDRLEN];
100 static State state = STATE_INVALID;
101 static int n_iteration = 0;
102 static int n_conflict = 0;
104 #define RANDOM_DEVICE "/dev/urandom"
106 static void init_rand_seed(void) {
110 /* Try to initialize seed from /dev/urandom, to make it a little
111 * less predictable, and to make sure that multiple machines
112 * booted at the same time choose different random seeds. */
113 if ((fd = open(RANDOM_DEVICE, O_RDONLY)) >= 0) {
114 read(fd, &seed, sizeof(seed));
118 /* If the initialization failed by some reason, we add the time to the seed */
119 seed ^= (unsigned) time(NULL);
124 static uint32_t pick_addr(uint32_t old_addr) {
128 unsigned r = (unsigned) rand();
130 /* Reduce to 16 bits */
132 r = (r >> 16) ^ (r & 0xFFFF);
134 addr = htonl(IPV4LL_NETWORK | (uint32_t) r);
136 } while (addr == old_addr);
141 static void* packet_new(const ArpPacketInfo *info, size_t *packet_len) {
146 assert(info->operation == ARP_REQUEST || info->operation == ARP_RESPONSE);
148 *packet_len = ARP_PACKET_SIZE;
149 r = avahi_new0(uint8_t, *packet_len);
151 r[1] = 1; /* HTYPE */
152 r[2] = 8; /* PTYPE */
153 r[4] = ETHER_ADDRLEN; /* HLEN */
155 r[7] = (uint8_t) info->operation;
157 memcpy(r+8, info->sender_hw_address, ETHER_ADDRLEN);
158 memcpy(r+14, &info->sender_ip_address, 4);
159 memcpy(r+18, info->target_hw_address, ETHER_ADDRLEN);
160 memcpy(r+24, &info->target_ip_address, 4);
165 static void *packet_new_probe(uint32_t ip_address, const uint8_t*hw_address, size_t *packet_len) {
168 memset(&info, 0, sizeof(info));
169 info.operation = ARP_REQUEST;
170 memcpy(info.sender_hw_address, hw_address, ETHER_ADDRLEN);
171 info.target_ip_address = ip_address;
173 return packet_new(&info, packet_len);
176 static void *packet_new_announcement(uint32_t ip_address, const uint8_t* hw_address, size_t *packet_len) {
179 memset(&info, 0, sizeof(info));
180 info.operation = ARP_REQUEST;
181 memcpy(info.sender_hw_address, hw_address, ETHER_ADDRLEN);
182 info.target_ip_address = ip_address;
183 info.sender_ip_address = ip_address;
185 return packet_new(&info, packet_len);
188 static int packet_parse(const void *data, size_t packet_len, ArpPacketInfo *info) {
189 const uint8_t *p = data;
193 if (packet_len < ARP_PACKET_SIZE)
196 /* Check HTYPE and PTYPE */
197 if (p[0] != 0 || p[1] != 1 || p[2] != 8 || p[3] != 0)
200 /* Check HLEN, PLEN, OPERATION */
201 if (p[4] != ETHER_ADDRLEN || p[5] != 4 || p[6] != 0 || (p[7] != 1 && p[7] != 2))
204 info->operation = p[7];
205 memcpy(info->sender_hw_address, p+8, ETHER_ADDRLEN);
206 memcpy(&info->sender_ip_address, p+14, 4);
207 memcpy(info->target_hw_address, p+18, ETHER_ADDRLEN);
208 memcpy(&info->target_ip_address, p+24, 4);
213 static void set_state(State st, int reset_counter) {
214 const char* const state_table[] = {
215 [STATE_INVALID] = "INVALID",
216 [STATE_WAITING_PROBE] = "WAITING_PROBE",
217 [STATE_PROBING] = "PROBING",
218 [STATE_WAITING_ANNOUNCE] = "WAITING_ANNOUNCE",
219 [STATE_ANNOUNCING] = "ANNOUNCING",
220 [STATE_RUNNING] = "RUNNING",
221 [STATE_SLEEPING] = "SLEEPING"
224 assert(st < STATE_MAX);
226 if (st == state && !reset_counter) {
228 daemon_log(LOG_DEBUG, "State iteration %s-%i", state_table[state], n_iteration);
230 daemon_log(LOG_DEBUG, "State transition %s-%i -> %s-0", state_table[state], n_iteration, state_table[st]);
236 static int add_address(int iface, uint32_t addr) {
239 daemon_log(LOG_INFO, "Selected address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf)));
243 static int remove_address(int iface, uint32_t addr) {
246 daemon_log(LOG_INFO, "Removing address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf)));
250 static int open_socket(int iface, uint8_t *hw_address) {
252 struct sockaddr_ll sa;
255 if ((fd = socket(PF_PACKET, SOCK_DGRAM, 0)) < 0) {
256 daemon_log(LOG_ERR, "socket() failed: %s", strerror(errno));
260 memset(&sa, 0, sizeof(sa));
261 sa.sll_family = AF_PACKET;
262 sa.sll_protocol = htons(ETH_P_ARP);
263 sa.sll_ifindex = iface;
265 if (bind(fd, (struct sockaddr*) &sa, sizeof(sa)) < 0) {
266 daemon_log(LOG_ERR, "bind() failed: %s", strerror(errno));
271 if (getsockname(fd, (struct sockaddr*) &sa, &sa_len) < 0) {
272 daemon_log(LOG_ERR, "getsockname() failed: %s", strerror(errno));
276 if (sa.sll_halen != ETHER_ADDRLEN) {
277 daemon_log(LOG_ERR, "getsockname() returned invalid hardware address.");
281 memcpy(hw_address, sa.sll_addr, ETHER_ADDRLEN);
292 static int send_packet(int fd, int iface, void *packet, size_t packet_len) {
293 struct sockaddr_ll sa;
297 assert(packet_len > 0);
299 memset(&sa, 0, sizeof(sa));
300 sa.sll_family = AF_PACKET;
301 sa.sll_protocol = htons(ETH_P_ARP);
302 sa.sll_ifindex = iface;
303 sa.sll_halen = ETHER_ADDRLEN;
304 memset(sa.sll_addr, 0xFF, ETHER_ADDRLEN);
306 if (sendto(fd, packet, packet_len, 0, (struct sockaddr*) &sa, sizeof(sa)) < 0) {
307 daemon_log(LOG_ERR, "sendto() failed: %s", strerror(errno));
314 static int recv_packet(int fd, void **packet, size_t *packet_len) {
316 struct sockaddr_ll sa;
325 if (ioctl(fd, FIONREAD, &s) < 0) {
326 daemon_log(LOG_ERR, "FIONREAD failed: %s", strerror(errno));
332 *packet_len = (size_t) s;
333 *packet = avahi_new(uint8_t, s);
336 if (recvfrom(fd, *packet, s, 0, (struct sockaddr*) &sa, &sa_len) < 0) {
337 daemon_log(LOG_ERR, "recvfrom() failed: %s", strerror(errno));
350 static int is_ll_address(uint32_t addr) {
351 return (ntohl(addr) & IPV4LL_NETMASK) == IPV4LL_NETWORK;
354 static struct timeval *elapse_time(struct timeval *tv, unsigned msec, unsigned jitter) {
357 gettimeofday(tv, NULL);
360 avahi_timeval_add(tv, (AvahiUsec) msec*1000);
363 avahi_timeval_add(tv, (AvahiUsec) (jitter*1000.0*rand()/(RAND_MAX+1.0)));
368 static int loop(int iface, uint32_t addr) {
369 int fd = -1, ret = -1;
370 struct timeval next_wakeup;
371 int next_wakeup_valid = 0;
373 void *in_packet = NULL;
374 size_t in_packet_len;
375 void *out_packet = NULL;
376 size_t out_packet_len;
377 uint8_t hw_address[ETHER_ADDRLEN];
378 struct pollfd pollfds[1];
384 } event = EVENT_NULL;
386 if ((fd = open_socket(iface, hw_address)) < 0)
389 if (addr && !is_ll_address(addr)) {
390 daemon_log(LOG_WARNING, "Requested address %s is not from IPv4LL range 169.254/16, ignoring.", inet_ntop(AF_INET, &addr, buf, sizeof(buf)));
398 for (i = 0; i < ETHER_ADDRLEN; i++)
399 a += hw_address[i]*i;
401 addr = htonl(IPV4LL_NETWORK | (uint32_t) a);
404 daemon_log(LOG_INFO, "Starting with address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf)));
406 memset(pollfds, 0, sizeof(pollfds));
408 pollfds[0].events = POLLIN;
414 if (state == STATE_INVALID) {
416 /* First, wait a random time */
417 set_state(STATE_WAITING_PROBE, 1);
419 elapse_time(&next_wakeup, 0, PROBE_WAIT*1000);
420 next_wakeup_valid = 1;
422 } else if ((state == STATE_WAITING_PROBE && event == EVENT_TIMEOUT) ||
423 (state == STATE_PROBING && event == EVENT_TIMEOUT && n_iteration < PROBE_NUM-2)) {
426 out_packet = packet_new_probe(addr, hw_address, &out_packet_len);
427 set_state(STATE_PROBING, 0);
429 elapse_time(&next_wakeup, PROBE_MIN*1000, (PROBE_MAX-PROBE_MIN)*1000);
430 next_wakeup_valid = 1;
432 } else if (state == STATE_PROBING && event == EVENT_TIMEOUT && n_iteration >= PROBE_NUM-2) {
434 /* Send the last probe */
435 out_packet = packet_new_probe(addr, hw_address, &out_packet_len);
436 set_state(STATE_WAITING_ANNOUNCE, 1);
438 elapse_time(&next_wakeup, ANNOUNCE_WAIT*1000, 0);
439 next_wakeup_valid = 1;
441 } else if ((state == STATE_WAITING_ANNOUNCE && event == EVENT_TIMEOUT) ||
442 (state == STATE_ANNOUNCING && event == EVENT_TIMEOUT && n_iteration < ANNOUNCE_NUM-1)) {
444 /* Send announcement packet */
445 out_packet = packet_new_announcement(addr, hw_address, &out_packet_len);
446 set_state(STATE_ANNOUNCING, 0);
448 elapse_time(&next_wakeup, ANNOUNCE_INTERVAL*1000, 0);
449 next_wakeup_valid = 1;
451 if (n_iteration == 0) {
452 add_address(iface, addr);
456 } else if ((state == STATE_ANNOUNCING && event == EVENT_TIMEOUT && n_iteration >= ANNOUNCE_NUM-1)) {
458 daemon_log(LOG_INFO, "Successfully claimed IP address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf)));
459 set_state(STATE_RUNNING, 0);
461 } else if (event == EVENT_PACKET) {
466 if (packet_parse(in_packet, in_packet_len, &info) < 0)
467 daemon_log(LOG_WARNING, "Failed to parse incoming ARP packet.");
471 if (info.sender_ip_address == addr) {
472 /* Normal conflict */
474 daemon_log(LOG_INFO, "Recieved conflicting normal ARP packet.");
475 } else if (state == STATE_WAITING_PROBE || state == STATE_PROBING || state == STATE_WAITING_ANNOUNCE) {
477 conflict = info.target_ip_address == addr && memcmp(hw_address, info.sender_hw_address, ETHER_ADDRLEN);
478 daemon_log(LOG_INFO, "Recieved conflicting probe ARP packet.");
483 if (state == STATE_RUNNING || state == STATE_ANNOUNCING)
484 remove_address(iface, addr);
486 /* Pick a new address */
487 addr = pick_addr(addr);
489 daemon_log(LOG_INFO, "Trying address %s", inet_ntop(AF_INET, &addr, buf, sizeof(buf)));
491 set_state(STATE_WAITING_PROBE, 1);
495 if (n_conflict >= MAX_CONFLICTS) {
496 daemon_log(LOG_WARNING, "Got too many conflicts, rate limiting new probes.");
497 elapse_time(&next_wakeup, RATE_LIMIT_INTERVAL*1000, PROBE_WAIT*1000);
499 elapse_time(&next_wakeup, 0, PROBE_WAIT*1000);
501 next_wakeup_valid = 1;
503 daemon_log(LOG_DEBUG, "Ignoring ARP packet.");
508 daemon_log(LOG_DEBUG, "sending...");
510 if (send_packet(fd, iface, out_packet, out_packet_len) < 0)
513 avahi_free(out_packet);
518 avahi_free(in_packet);
524 if (next_wakeup_valid) {
525 usec = avahi_age(&next_wakeup);
526 timeout = usec < 0 ? (int) (-usec/1000) : 0;
529 daemon_log(LOG_DEBUG, "sleeping %ims", timeout);
531 while ((r = poll(pollfds, 1, timeout)) < 0 && errno == EINTR)
535 daemon_log(LOG_ERR, "poll() failed: %s", strerror(r));
538 event = EVENT_TIMEOUT;
539 next_wakeup_valid = 0;
541 assert(pollfds[0].revents == POLLIN);
543 if (recv_packet(fd, &in_packet, &in_packet_len) < 0)
547 event = EVENT_PACKET;
555 avahi_free(out_packet);
556 avahi_free(in_packet);
564 static int get_ifindex(const char *name) {
568 if ((fd = socket(PF_INET, SOCK_DGRAM, 0)) < 0) {
569 daemon_log(LOG_ERR, "socket() failed: %s", strerror(errno));
573 memset(&ifreq, 0, sizeof(ifreq));
574 strncpy(ifreq.ifr_name, name, IFNAMSIZ-1);
575 ifreq.ifr_name[IFNAMSIZ-1] = 0;
577 if (ioctl(fd, SIOCGIFINDEX, &ifreq) < 0) {
578 daemon_log(LOG_ERR, "SIOCGIFINDEX failed: %s", strerror(errno));
582 return ifreq.ifr_ifindex;
592 int main(int argc, char*argv[]) {
599 if ((ifindex = get_ifindex(argc >= 2 ? argv[1] : "eth0")) < 0)
603 addr = inet_addr(argv[2]);
605 if (loop(ifindex, addr) < 0)
621 - chroot/drop privs/caps
625 - store last used address