1 /* vi: set sw=4 ts=4: */
5 * Russ Dill <Russ.Dill@asu.edu> July 2001
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
23 #define WANT_PIDFILE 1
28 #include <asm/types.h>
29 #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined(_NEWLIB_VERSION)
30 # include <netpacket/packet.h>
31 # include <net/ethernet.h>
33 # include <linux/if_packet.h>
34 # include <linux/if_ether.h>
36 #include <linux/filter.h>
38 /* struct client_config_t client_config is in bb_common_bufsiz1 */
41 /*** Script execution code ***/
43 /* get a rough idea of how long an option will be (rounding up...) */
44 static const uint8_t len_of_option_as_string[] = {
45 [OPTION_IP] = sizeof("255.255.255.255 "),
46 [OPTION_IP_PAIR] = sizeof("255.255.255.255 ") * 2,
47 [OPTION_STATIC_ROUTES]= sizeof("255.255.255.255/32 255.255.255.255 "),
49 #if ENABLE_FEATURE_UDHCP_RFC3397
52 [OPTION_BOOLEAN] = sizeof("yes "),
53 [OPTION_U8] = sizeof("255 "),
54 [OPTION_U16] = sizeof("65535 "),
55 [OPTION_S16] = sizeof("-32768 "),
56 [OPTION_U32] = sizeof("4294967295 "),
57 [OPTION_S32] = sizeof("-2147483684 "),
60 /* note: ip is a pointer to an IP in network order, possibly misaliged */
61 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
63 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
66 /* really simple implementation, just count the bits */
67 static int mton(uint32_t mask)
70 mask = ntohl(mask); /* 111110000-like bit pattern */
78 /* Create "opt_name=opt_value" string */
79 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_option *type_p, const char *opt_name)
81 unsigned upper_length;
82 int len, type, optlen;
89 /* option points to OPT_DATA, need to go back and get OPT_LEN */
90 len = option[OPT_LEN - OPT_DATA];
91 type = type_p->flags & OPTION_TYPE_MASK;
92 optlen = dhcp_option_lengths[type];
93 upper_length = len_of_option_as_string[type] * (len / optlen);
95 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
96 dest += sprintf(ret, "%s=", opt_name);
98 while (len >= optlen) {
101 dest += sprint_nip(dest, "", option);
106 dest += sprint_nip(dest, "", option);
107 // TODO: it can be a list only if (type_p->flags & OPTION_LIST).
108 // Should we bail out/warn if we see multi-ip option which is
109 // not allowed to be such? For example, DHCP_BROADCAST...
112 dest += sprintf(dest, *option ? "yes" : "no");
115 dest += sprintf(dest, "%u", *option);
118 move_from_unaligned16(val_u16, option);
119 dest += sprintf(dest, "%u", ntohs(val_u16));
122 move_from_unaligned16(val_s16, option);
123 dest += sprintf(dest, "%d", ntohs(val_s16));
126 move_from_unaligned32(val_u32, option);
127 dest += sprintf(dest, "%lu", (unsigned long) ntohl(val_u32));
130 move_from_unaligned32(val_s32, option);
131 dest += sprintf(dest, "%ld", (long) ntohl(val_s32));
134 memcpy(dest, option, len);
136 return ret; /* Short circuit this case */
137 case OPTION_STATIC_ROUTES: {
138 /* Option binary format:
139 * mask [one byte, 0..32]
140 * ip [big endian, 0..4 bytes depending on mask]
141 * router [big endian, 4 bytes]
144 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
146 const char *pfx = "";
148 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
161 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
162 while (--bytes >= 0) {
170 dest += sprint_nip(dest, pfx, (void*) &nip);
172 dest += sprintf(dest, "/%u ", mask);
174 dest += sprint_nip(dest, "", option);
181 #if ENABLE_FEATURE_UDHCP_RFC3397
183 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
184 dest = dname_dec(option, len, ret);
189 /* error. return "optname=" string */
203 /* put all the parameters into the environment */
204 static char **fill_envp(struct dhcp_packet *packet)
209 const char *opt_name;
214 for (i = 0; dhcp_options[i].code; i++) {
215 if (udhcp_get_option(packet, dhcp_options[i].code)) {
217 if (dhcp_options[i].code == DHCP_SUBNET)
218 num_options++; /* for mton */
221 if (packet->siaddr_nip)
223 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
226 if (!(over & FILE_FIELD) && packet->file[0])
228 if (!(over & SNAME_FIELD) && packet->sname[0])
232 curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
233 *curr = xasprintf("interface=%s", client_config.interface);
239 *curr = xmalloc(sizeof("ip=255.255.255.255"));
240 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
243 opt_name = dhcp_option_strings;
246 temp = udhcp_get_option(packet, dhcp_options[i].code);
249 *curr = xmalloc_optname_optval(temp, &dhcp_options[i], opt_name);
252 /* Fill in a subnet bits option for things like /24 */
253 if (dhcp_options[i].code == DHCP_SUBNET) {
255 move_from_unaligned32(subnet, temp);
256 *curr = xasprintf("mask=%d", mton(subnet));
260 opt_name += strlen(opt_name) + 1;
263 if (packet->siaddr_nip) {
264 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
265 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
268 if (!(over & FILE_FIELD) && packet->file[0]) {
269 /* watch out for invalid packets */
270 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
273 if (!(over & SNAME_FIELD) && packet->sname[0]) {
274 /* watch out for invalid packets */
275 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
281 /* Call a script with a par file and env vars */
282 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
287 if (client_config.script == NULL)
290 envp = fill_envp(packet);
293 log1("Executing %s %s", client_config.script, name);
294 argv[0] = (char*) client_config.script;
295 argv[1] = (char*) name;
297 spawn_and_wait(argv);
299 for (curr = envp; *curr; curr++) {
308 /*** Sending/receiving packets ***/
310 static ALWAYS_INLINE uint32_t random_xid(void)
315 /* Initialize the packet with the proper defaults */
316 static void init_packet(struct dhcp_packet *packet, char type)
318 udhcp_init_header(packet, type);
319 memcpy(packet->chaddr, client_config.client_mac, 6);
320 if (client_config.clientid)
321 udhcp_add_option_string(packet->options, client_config.clientid);
322 if (client_config.hostname)
323 udhcp_add_option_string(packet->options, client_config.hostname);
324 if (client_config.fqdn)
325 udhcp_add_option_string(packet->options, client_config.fqdn);
326 if (type != DHCPDECLINE
327 && type != DHCPRELEASE
328 && client_config.vendorclass
330 udhcp_add_option_string(packet->options, client_config.vendorclass);
334 /* Add a parameter request list for stubborn DHCP servers. Pull the data
335 * from the struct in options.c. Don't do bounds checking here because it
336 * goes towards the head of the packet. */
337 static void add_param_req_option(struct dhcp_packet *packet)
340 int end = udhcp_end_option(packet->options);
343 for (i = 0; (c = dhcp_options[i].code) != 0; i++) {
344 if (( (dhcp_options[i].flags & OPTION_REQ)
345 && !client_config.no_default_options
347 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
349 packet->options[end + OPT_DATA + len] = c;
354 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
355 packet->options[end + OPT_LEN] = len;
356 packet->options[end + OPT_DATA + len] = DHCP_END;
361 * 4.4.4 Use of broadcast and unicast
363 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
364 * messages, unless the client knows the address of a DHCP server.
365 * The client unicasts DHCPRELEASE messages to the server. Because
366 * the client is declining the use of the IP address supplied by the server,
367 * the client broadcasts DHCPDECLINE messages.
369 * When the DHCP client knows the address of a DHCP server, in either
370 * INIT or REBOOTING state, the client may use that address
371 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
372 * The client may also use unicast to send DHCPINFORM messages
373 * to a known DHCP server. If the client receives no response to DHCP
374 * messages sent to the IP address of a known DHCP server, the DHCP
375 * client reverts to using the IP broadcast address.
378 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
380 return udhcp_send_raw_packet(packet,
381 /*src*/ INADDR_ANY, CLIENT_PORT,
382 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
383 client_config.ifindex);
386 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
387 static int send_discover(uint32_t xid, uint32_t requested)
389 struct dhcp_packet packet;
391 init_packet(&packet, DHCPDISCOVER);
394 udhcp_add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
395 /* Explicitly saying that we want RFC-compliant packets helps
396 * some buggy DHCP servers to NOT send bigger packets */
397 udhcp_add_simple_option(packet.options, DHCP_MAX_SIZE, htons(576));
398 add_param_req_option(&packet);
400 bb_info_msg("Sending discover...");
401 return raw_bcast_from_client_config_ifindex(&packet);
404 /* Broadcast a DHCP request message */
405 /* RFC 2131 3.1 paragraph 3:
406 * "The client _broadcasts_ a DHCPREQUEST message..."
408 static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
410 struct dhcp_packet packet;
413 init_packet(&packet, DHCPREQUEST);
415 udhcp_add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
416 udhcp_add_simple_option(packet.options, DHCP_SERVER_ID, server);
417 add_param_req_option(&packet);
419 addr.s_addr = requested;
420 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
421 return raw_bcast_from_client_config_ifindex(&packet);
424 /* Unicast or broadcast a DHCP renew message */
425 static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
427 struct dhcp_packet packet;
429 init_packet(&packet, DHCPREQUEST);
431 packet.ciaddr = ciaddr;
432 add_param_req_option(&packet);
434 bb_info_msg("Sending renew...");
436 return udhcp_send_kernel_packet(&packet,
438 server, SERVER_PORT);
439 return raw_bcast_from_client_config_ifindex(&packet);
442 #if ENABLE_FEATURE_UDHCPC_ARPING
443 /* Broadcast a DHCP decline message */
444 static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
446 struct dhcp_packet packet;
448 init_packet(&packet, DHCPDECLINE);
450 udhcp_add_simple_option(packet.options, DHCP_REQUESTED_IP, requested);
451 udhcp_add_simple_option(packet.options, DHCP_SERVER_ID, server);
453 bb_info_msg("Sending decline...");
454 return raw_bcast_from_client_config_ifindex(&packet);
458 /* Unicast a DHCP release message */
459 static int send_release(uint32_t server, uint32_t ciaddr)
461 struct dhcp_packet packet;
463 init_packet(&packet, DHCPRELEASE);
464 packet.xid = random_xid();
465 packet.ciaddr = ciaddr;
467 udhcp_add_simple_option(packet.options, DHCP_SERVER_ID, server);
469 bb_info_msg("Sending release...");
470 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
473 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
474 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
477 struct ip_udp_dhcp_packet packet;
480 memset(&packet, 0, sizeof(packet));
481 bytes = safe_read(fd, &packet, sizeof(packet));
483 log1("Packet read error, ignoring");
484 /* NB: possible down interface, etc. Caller should pause. */
485 return bytes; /* returns -1 */
488 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
489 log1("Packet is too short, ignoring");
493 if (bytes < ntohs(packet.ip.tot_len)) {
494 /* packet is bigger than sizeof(packet), we did partial read */
495 log1("Oversized packet, ignoring");
499 /* ignore any extra garbage bytes */
500 bytes = ntohs(packet.ip.tot_len);
502 /* make sure its the right packet for us, and that it passes sanity checks */
503 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
504 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
505 || packet.udp.dest != htons(CLIENT_PORT)
506 /* || bytes > (int) sizeof(packet) - can't happen */
507 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
509 log1("Unrelated/bogus packet, ignoring");
513 /* verify IP checksum */
514 check = packet.ip.check;
516 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
517 log1("Bad IP header checksum, ignoring");
521 /* verify UDP checksum. IP header has to be modified for this */
522 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
523 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
524 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
525 check = packet.udp.check;
526 packet.udp.check = 0;
527 if (check && check != udhcp_checksum(&packet, bytes)) {
528 log1("Packet with bad UDP checksum received, ignoring");
532 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
534 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
535 bb_info_msg("Packet with bad magic, ignoring");
538 log1("Got valid DHCP packet");
539 udhcp_dump_packet(dhcp_pkt);
540 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
546 static int sockfd = -1;
548 #define LISTEN_NONE 0
549 #define LISTEN_KERNEL 1
551 static smallint listen_mode;
553 /* initial state: (re)start DHCP negotiation */
554 #define INIT_SELECTING 0
555 /* discover was sent, DHCPOFFER reply received */
557 /* select/renew was sent, DHCPACK reply received */
559 /* half of lease passed, want to renew it by sending unicast renew requests */
561 /* renew requests were not answered, lease is almost over, send broadcast renew */
563 /* manually requested renew (SIGUSR1) */
564 #define RENEW_REQUESTED 5
565 /* release, possibly manually requested (SIGUSR2) */
567 static smallint state;
569 static int udhcp_raw_socket(int ifindex)
572 struct sockaddr_ll sock;
577 * I've selected not to see LL header, so BPF doesn't see it, too.
578 * The filter may also pass non-IP and non-ARP packets, but we do
579 * a more complete check when receiving the message in userspace.
581 * and filter shamelessly stolen from:
583 * http://www.flamewarmaster.de/software/dhcpclient/
585 * There are a few other interesting ideas on that page (look under
586 * "Motivation"). Use of netlink events is most interesting. Think
587 * of various network servers listening for events and reconfiguring.
588 * That would obsolete sending HUP signals and/or make use of restarts.
590 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
593 * TODO: make conditional?
595 #define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
596 static const struct sock_filter filter_instr[] = {
598 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
599 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
600 /* ugly check for arp on ethernet-like and IPv4 */
601 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
602 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
604 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
605 /* check udp source and destination ports */
606 BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
607 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */
609 BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
610 BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
612 static const struct sock_fprog filter_prog = {
613 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
614 /* casting const away: */
615 .filter = (struct sock_filter *) filter_instr,
618 log1("Opening raw socket on ifindex %d", ifindex); //log2?
620 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
621 log1("Got raw socket fd %d", fd); //log2?
623 if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
624 /* Use only if standard ports are in use */
625 /* Ignoring error (kernel may lack support for this) */
626 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
627 sizeof(filter_prog)) >= 0)
628 log1("Attached filter to raw socket fd %d", fd); // log?
631 sock.sll_family = AF_PACKET;
632 sock.sll_protocol = htons(ETH_P_IP);
633 sock.sll_ifindex = ifindex;
634 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
635 log1("Created raw socket");
640 static void change_listen_mode(int new_mode)
642 log1("Entering listen mode: %s",
643 new_mode != LISTEN_NONE
644 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
648 listen_mode = new_mode;
653 if (new_mode == LISTEN_KERNEL)
654 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
655 else if (new_mode != LISTEN_NONE)
656 sockfd = udhcp_raw_socket(client_config.ifindex);
657 /* else LISTEN_NONE: sockfd stays closed */
660 static void perform_renew(void)
662 bb_info_msg("Performing a DHCP renew");
665 change_listen_mode(LISTEN_KERNEL);
668 state = RENEW_REQUESTED;
670 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
671 udhcp_run_script(NULL, "deconfig");
674 change_listen_mode(LISTEN_RAW);
675 state = INIT_SELECTING;
682 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
684 char buffer[sizeof("255.255.255.255")];
685 struct in_addr temp_addr;
687 /* send release packet */
688 if (state == BOUND || state == RENEWING || state == REBINDING) {
689 temp_addr.s_addr = server_addr;
690 strcpy(buffer, inet_ntoa(temp_addr));
691 temp_addr.s_addr = requested_ip;
692 bb_info_msg("Unicasting a release of %s to %s",
693 inet_ntoa(temp_addr), buffer);
694 send_release(server_addr, requested_ip); /* unicast */
695 udhcp_run_script(NULL, "deconfig");
697 bb_info_msg("Entering released state");
699 change_listen_mode(LISTEN_NONE);
703 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
706 int len = strnlen(str, 255);
707 storage = xzalloc(len + extra + OPT_DATA);
708 storage[OPT_CODE] = code;
709 storage[OPT_LEN] = len + extra;
710 memcpy(storage + extra + OPT_DATA, str, len);
715 static void client_background(void)
718 logmode &= ~LOGMODE_STDIO;
719 /* rewrite pidfile, as our pid is different now */
720 write_pidfile(client_config.pidfile);
724 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
725 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
727 uint8_t *temp, *message;
728 const char *str_c, *str_V, *str_h, *str_F, *str_r;
729 IF_FEATURE_UDHCP_PORT(char *str_P;)
730 llist_t *list_O = NULL;
731 int tryagain_timeout = 20;
732 int discover_timeout = 3;
733 int discover_retries = 3;
734 uint32_t server_addr = server_addr; /* for compiler */
735 uint32_t requested_ip = 0;
737 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
739 int timeout; /* must be signed */
740 unsigned already_waited_sec;
745 struct dhcp_packet packet;
749 static const char udhcpc_longopts[] ALIGN1 =
750 "clientid\0" Required_argument "c"
751 "clientid-none\0" No_argument "C"
752 "vendorclass\0" Required_argument "V"
753 "hostname\0" Required_argument "H"
754 "fqdn\0" Required_argument "F"
755 "interface\0" Required_argument "i"
756 "now\0" No_argument "n"
757 "pidfile\0" Required_argument "p"
758 "quit\0" No_argument "q"
759 "release\0" No_argument "R"
760 "request\0" Required_argument "r"
761 "script\0" Required_argument "s"
762 "timeout\0" Required_argument "T"
763 "version\0" No_argument "v"
764 "retries\0" Required_argument "t"
765 "tryagain\0" Required_argument "A"
766 "syslog\0" No_argument "S"
767 "request-option\0" Required_argument "O"
768 "no-default-options\0" No_argument "o"
769 "foreground\0" No_argument "f"
770 "background\0" No_argument "b"
771 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
772 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
796 /* The rest has variable bit positions, need to be clever */
798 USE_FOR_MMU( OPTBIT_b,)
799 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
800 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
801 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
802 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
803 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
806 /* Default options. */
807 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
808 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
809 client_config.interface = "eth0";
810 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
811 str_V = "udhcp "BB_VER;
813 /* Parse command line */
814 /* Cc: mutually exclusive; O: list; -T,-t,-A take numeric param */
815 opt_complementary = "c--C:C--c:O::T+:t+:A+"
816 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
820 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
821 opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:of"
823 IF_FEATURE_UDHCPC_ARPING("a")
824 IF_FEATURE_UDHCP_PORT("P:")
826 , &str_c, &str_V, &str_h, &str_h, &str_F
827 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
828 , &client_config.script /* s */
829 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
831 IF_FEATURE_UDHCP_PORT(, &str_P)
832 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
836 if (opt & (OPT_h|OPT_H))
837 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
839 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
840 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
841 /* Flag bits: 0000NEOS
842 * S: 1 = Client requests server to update A RR in DNS as well as PTR
843 * O: 1 = Server indicates to client that DNS has been updated regardless
844 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
845 * not "host.domain.com". Format 0 is obsolete.
846 * N: 1 = Client requests server to not update DNS (S must be 0 then)
847 * Two [0] bytes which follow are deprecated and must be 0.
849 client_config.fqdn[OPT_DATA + 0] = 0x1;
850 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
851 /*client_config.fqdn[OPT_DATA + 2] = 0; */
854 requested_ip = inet_addr(str_r);
855 #if ENABLE_FEATURE_UDHCP_PORT
857 CLIENT_PORT = xatou16(str_P);
858 SERVER_PORT = CLIENT_PORT - 1;
862 client_config.no_default_options = 1;
864 char *optstr = llist_pop(&list_O);
865 int n = index_in_strings(dhcp_option_strings, optstr);
867 bb_error_msg_and_die("unknown option '%s'", optstr);
868 n = dhcp_options[n].code;
869 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
872 if (udhcp_read_interface(client_config.interface,
873 &client_config.ifindex,
875 client_config.client_mac)
881 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
882 } else if (!(opt & OPT_C)) {
883 /* not set and not suppressed, set the default client ID */
884 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
885 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
886 memcpy(client_config.clientid + OPT_DATA+1, client_config.client_mac, 6);
888 if (str_V[0] != '\0')
889 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
891 /* on NOMMU reexec (i.e., background) early */
892 if (!(opt & OPT_f)) {
893 bb_daemonize_or_rexec(0 /* flags */, argv);
894 logmode = LOGMODE_NONE;
898 openlog(applet_name, LOG_PID, LOG_DAEMON);
899 logmode |= LOGMODE_SYSLOG;
902 /* Make sure fd 0,1,2 are open */
904 /* Equivalent of doing a fflush after every \n */
907 write_pidfile(client_config.pidfile);
908 /* Goes to stdout (unless NOMMU) and possibly syslog */
909 bb_info_msg("%s (v"BB_VER") started", applet_name);
910 /* Set up the signal pipe */
912 /* We want random_xid to be random... */
913 srand(monotonic_us());
915 state = INIT_SELECTING;
916 udhcp_run_script(NULL, "deconfig");
917 change_listen_mode(LISTEN_RAW);
920 already_waited_sec = 0;
922 /* Main event loop. select() waits on signal pipe and possibly
924 * "continue" statements in code below jump to the top of the loop.
927 /* silence "uninitialized!" warning */
928 unsigned timestamp_before_wait = timestamp_before_wait;
930 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
932 /* Was opening raw or udp socket here
933 * if (listen_mode != LISTEN_NONE && sockfd < 0),
934 * but on fast network renew responses return faster
935 * than we open sockets. Thus this code is moved
936 * to change_listen_mode(). Thus we open listen socket
937 * BEFORE we send renew request (see "case BOUND:"). */
939 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
941 tv.tv_sec = timeout - already_waited_sec;
944 /* If we already timed out, fall through with retval = 0, else... */
945 if ((int)tv.tv_sec > 0) {
946 timestamp_before_wait = (unsigned)monotonic_sec();
947 log1("Waiting on select...");
948 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
950 /* EINTR? A signal was caught, don't panic */
951 if (errno == EINTR) {
952 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
955 /* Else: an error occured, panic! */
956 bb_perror_msg_and_die("select");
960 /* If timeout dropped to zero, time to become active:
961 * resend discover/renew/whatever
964 /* We will restart the wait in any case */
965 already_waited_sec = 0;
969 if (packet_num < discover_retries) {
973 send_discover(xid, requested_ip);
974 timeout = discover_timeout;
979 udhcp_run_script(NULL, "leasefail");
980 #if BB_MMU /* -b is not supported on NOMMU */
981 if (opt & OPT_b) { /* background if no lease */
982 bb_info_msg("No lease, forking to background");
984 /* do not background again! */
985 opt = ((opt & ~OPT_b) | OPT_f);
988 if (opt & OPT_n) { /* abort if no lease */
989 bb_info_msg("No lease, failing");
993 /* wait before trying again */
994 timeout = tryagain_timeout;
998 if (packet_num < discover_retries) {
999 /* send broadcast select packet */
1000 send_select(xid, server_addr, requested_ip);
1001 timeout = discover_timeout;
1005 /* Timed out, go back to init state.
1006 * "discover...select...discover..." loops
1007 * were seen in the wild. Treat them similarly
1008 * to "no response to discover" case */
1009 change_listen_mode(LISTEN_RAW);
1010 state = INIT_SELECTING;
1013 /* 1/2 lease passed, enter renewing state */
1015 change_listen_mode(LISTEN_KERNEL);
1016 log1("Entering renew state");
1017 /* fall right through */
1018 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1019 case_RENEW_REQUESTED:
1022 /* send an unicast renew request */
1023 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1024 * a new UDP socket for sending inside send_renew.
1025 * I hazard to guess existing listening socket
1026 * is somehow conflicting with it, but why is it
1027 * not deterministic then?! Strange.
1028 * Anyway, it does recover by eventually failing through
1029 * into INIT_SELECTING state.
1031 send_renew(xid, server_addr, requested_ip);
1035 /* Timed out, enter rebinding state */
1036 log1("Entering rebinding state");
1038 /* fall right through */
1040 /* Switch to bcast receive */
1041 change_listen_mode(LISTEN_RAW);
1042 /* Lease is *really* about to run out,
1043 * try to find DHCP server using broadcast */
1045 /* send a broadcast renew request */
1046 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1050 /* Timed out, enter init state */
1051 bb_info_msg("Lease lost, entering init state");
1052 udhcp_run_script(NULL, "deconfig");
1053 state = INIT_SELECTING;
1054 /*timeout = 0; - already is */
1057 /* case RELEASED: */
1059 /* yah, I know, *you* say it would never happen */
1061 continue; /* back to main loop */
1062 } /* if select timed out */
1064 /* select() didn't timeout, something happened */
1066 /* Is it a signal? */
1067 /* note: udhcp_sp_read checks FD_ISSET before reading */
1068 switch (udhcp_sp_read(&rfds)) {
1071 if (state == RENEW_REQUESTED)
1072 goto case_RENEW_REQUESTED;
1073 /* Start things over */
1075 /* Kill any timeouts, user wants this to hurry along */
1079 perform_release(requested_ip, server_addr);
1083 bb_info_msg("Received SIGTERM");
1084 if (opt & OPT_R) /* release on quit */
1085 perform_release(requested_ip, server_addr);
1089 /* Is it a packet? */
1090 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1096 /* A packet is ready, read it */
1097 if (listen_mode == LISTEN_KERNEL)
1098 len = udhcp_recv_kernel_packet(&packet, sockfd);
1100 len = udhcp_recv_raw_packet(&packet, sockfd);
1102 /* Error is severe, reopen socket */
1103 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1104 sleep(discover_timeout); /* 3 seconds by default */
1105 change_listen_mode(listen_mode); /* just close and reopen */
1107 /* If this packet will turn out to be unrelated/bogus,
1108 * we will go back and wait for next one.
1109 * Be sure timeout is properly decreased. */
1110 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1115 if (packet.xid != xid) {
1116 log1("xid %x (our is %x), ignoring packet",
1117 (unsigned)packet.xid, (unsigned)xid);
1121 /* Ignore packets that aren't for us */
1122 if (packet.hlen != 6
1123 || memcmp(packet.chaddr, client_config.client_mac, 6)
1125 //FIXME: need to also check that last 10 bytes are zero
1126 log1("chaddr does not match, ignoring packet"); // log2?
1130 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1131 if (message == NULL) {
1132 bb_error_msg("no message type option, ignoring packet");
1137 case INIT_SELECTING:
1138 /* Must be a DHCPOFFER to one of our xid's */
1139 if (*message == DHCPOFFER) {
1140 /* TODO: why we don't just fetch server's IP from IP header? */
1141 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1143 bb_error_msg("no server ID in message");
1145 /* still selecting - this server looks bad */
1147 /* it IS unaligned sometimes, don't "optimize" */
1148 move_from_unaligned32(server_addr, temp);
1150 requested_ip = packet.yiaddr;
1152 /* enter requesting state */
1156 already_waited_sec = 0;
1161 case RENEW_REQUESTED:
1163 if (*message == DHCPACK) {
1164 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1166 bb_error_msg("no lease time with ACK, using 1 hour lease");
1167 lease_seconds = 60 * 60;
1169 /* it IS unaligned sometimes, don't "optimize" */
1170 move_from_unaligned32(lease_seconds, temp);
1171 lease_seconds = ntohl(lease_seconds);
1172 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1173 if (lease_seconds < 10) /* and not too small */
1176 #if ENABLE_FEATURE_UDHCPC_ARPING
1178 /* RFC 2131 3.1 paragraph 5:
1179 * "The client receives the DHCPACK message with configuration
1180 * parameters. The client SHOULD perform a final check on the
1181 * parameters (e.g., ARP for allocated network address), and notes
1182 * the duration of the lease specified in the DHCPACK message. At this
1183 * point, the client is configured. If the client detects that the
1184 * address is already in use (e.g., through the use of ARP),
1185 * the client MUST send a DHCPDECLINE message to the server and restarts
1186 * the configuration process..." */
1187 if (!arpping(packet.yiaddr,
1190 client_config.client_mac,
1191 client_config.interface)
1193 bb_info_msg("Offered address is in use "
1194 "(got ARP reply), declining");
1195 send_decline(xid, server_addr, packet.yiaddr);
1197 if (state != REQUESTING)
1198 udhcp_run_script(NULL, "deconfig");
1199 change_listen_mode(LISTEN_RAW);
1200 state = INIT_SELECTING;
1202 timeout = tryagain_timeout;
1204 already_waited_sec = 0;
1205 continue; /* back to main loop */
1209 /* enter bound state */
1210 timeout = lease_seconds / 2;
1212 struct in_addr temp_addr;
1213 temp_addr.s_addr = packet.yiaddr;
1214 bb_info_msg("Lease of %s obtained, lease time %u",
1215 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1217 requested_ip = packet.yiaddr;
1218 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1221 change_listen_mode(LISTEN_NONE);
1222 if (opt & OPT_q) { /* quit after lease */
1223 if (opt & OPT_R) /* release on quit */
1224 perform_release(requested_ip, server_addr);
1227 /* future renew failures should not exit (JM) */
1229 #if BB_MMU /* NOMMU case backgrounded earlier */
1230 if (!(opt & OPT_f)) {
1231 client_background();
1232 /* do not background again! */
1233 opt = ((opt & ~OPT_b) | OPT_f);
1236 already_waited_sec = 0;
1237 continue; /* back to main loop */
1239 if (*message == DHCPNAK) {
1240 /* return to init state */
1241 bb_info_msg("Received DHCP NAK");
1242 udhcp_run_script(&packet, "nak");
1243 if (state != REQUESTING)
1244 udhcp_run_script(NULL, "deconfig");
1245 change_listen_mode(LISTEN_RAW);
1246 sleep(3); /* avoid excessive network traffic */
1247 state = INIT_SELECTING;
1251 already_waited_sec = 0;
1254 /* case BOUND: - ignore all packets */
1255 /* case RELEASED: - ignore all packets */
1257 /* back to main loop */
1258 } /* for (;;) - main loop ends */
1263 /*if (client_config.pidfile) - remove_pidfile has its own check */
1264 remove_pidfile(client_config.pidfile);