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
50 [OPTION_DNS_STRING ] = 1, /* unused */
51 /* Hmmm, this severely overestimates size if SIP_SERVERS option
52 * is in domain name form: N-byte option in binary form
53 * mallocs ~16*N bytes. But it is freed almost at once.
55 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
57 // [OPTION_BOOLEAN ] = sizeof("yes "),
58 [OPTION_U8 ] = sizeof("255 "),
59 [OPTION_U16 ] = sizeof("65535 "),
60 // [OPTION_S16 ] = sizeof("-32768 "),
61 [OPTION_U32 ] = sizeof("4294967295 "),
62 [OPTION_S32 ] = sizeof("-2147483684 "),
65 /* note: ip is a pointer to an IP in network order, possibly misaliged */
66 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
68 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
71 /* really simple implementation, just count the bits */
72 static int mton(uint32_t mask)
75 mask = ntohl(mask); /* 111110000-like bit pattern */
83 /* Create "opt_name=opt_value" string */
84 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
86 unsigned upper_length;
87 int len, type, optlen;
90 /* option points to OPT_DATA, need to go back and get OPT_LEN */
91 len = option[OPT_LEN - OPT_DATA];
92 type = optflag->flags & OPTION_TYPE_MASK;
93 optlen = dhcp_option_lengths[type];
94 upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
96 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
97 dest += sprintf(ret, "%s=", opt_name);
99 while (len >= optlen) {
102 dest += sprint_nip(dest, "", option);
107 dest += sprint_nip(dest, "", option);
108 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
109 // Should we bail out/warn if we see multi-ip option which is
110 // not allowed to be such? For example, DHCP_BROADCAST...
112 // case OPTION_BOOLEAN:
113 // dest += sprintf(dest, *option ? "yes" : "no");
116 dest += sprintf(dest, "%u", *option);
121 move_from_unaligned16(val_u16, option);
122 dest += sprintf(dest, "%u", ntohs(val_u16));
128 move_from_unaligned32(val_u32, option);
129 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
133 memcpy(dest, option, len);
135 return ret; /* Short circuit this case */
136 case OPTION_STATIC_ROUTES: {
137 /* Option binary format:
138 * mask [one byte, 0..32]
139 * ip [big endian, 0..4 bytes depending on mask]
140 * router [big endian, 4 bytes]
143 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
145 const char *pfx = "";
147 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
160 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
161 while (--bytes >= 0) {
169 dest += sprint_nip(dest, pfx, (void*) &nip);
171 dest += sprintf(dest, "/%u ", mask);
173 dest += sprint_nip(dest, "", option);
180 #if ENABLE_FEATURE_UDHCP_RFC3397
181 case OPTION_DNS_STRING:
182 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
183 dest = dname_dec(option, len, ret);
188 /* error. return "optname=" string */
190 case OPTION_SIP_SERVERS:
191 /* Option binary format:
193 * type=0: domain names, dns-compressed
198 if (option[-1] == 0) {
199 dest = dname_dec(option, len, ret);
205 if (option[-1] == 1) {
206 const char *pfx = "";
211 dest += sprint_nip(dest, pfx, option);
229 /* put all the parameters into the environment */
230 static char **fill_envp(struct dhcp_packet *packet)
235 const char *opt_name;
237 uint8_t overload = 0;
239 /* We need 6 elements for:
241 * "ip=N.N.N.N" from packet->yiaddr
242 * "siaddr=IP" from packet->siaddr_nip (unless 0)
243 * "boot_file=FILE" from packet->file (unless overloaded)
244 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
248 /* +1 element for each option, +2 for subnet option: */
250 for (i = 0; dhcp_optflags[i].code; i++) {
251 if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
252 if (dhcp_optflags[i].code == DHCP_SUBNET)
253 envc++; /* for mton */
257 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
261 curr = envp = xzalloc(sizeof(char *) * envc);
263 *curr = xasprintf("interface=%s", client_config.interface);
269 *curr = xmalloc(sizeof("ip=255.255.255.255"));
270 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
273 opt_name = dhcp_option_strings;
276 temp = udhcp_get_option(packet, dhcp_optflags[i].code);
279 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
281 if (dhcp_optflags[i].code == DHCP_SUBNET) {
282 /* Subnet option: make things like "$ip/$mask" possible */
284 move_from_unaligned32(subnet, temp);
285 *curr = xasprintf("mask=%d", mton(subnet));
289 opt_name += strlen(opt_name) + 1;
292 if (packet->siaddr_nip) {
293 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
294 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
297 if (!(overload & FILE_FIELD) && packet->file[0]) {
298 /* watch out for invalid packets */
299 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
302 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
303 /* watch out for invalid packets */
304 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
310 /* Call a script with a par file and env vars */
311 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
316 if (client_config.script == NULL)
319 envp = fill_envp(packet);
322 log1("Executing %s %s", client_config.script, name);
323 argv[0] = (char*) client_config.script;
324 argv[1] = (char*) name;
326 spawn_and_wait(argv);
328 for (curr = envp; *curr; curr++) {
330 bb_unsetenv_and_free(*curr);
336 /*** Sending/receiving packets ***/
338 static ALWAYS_INLINE uint32_t random_xid(void)
343 /* Initialize the packet with the proper defaults */
344 static void init_packet(struct dhcp_packet *packet, char type)
346 udhcp_init_header(packet, type);
347 memcpy(packet->chaddr, client_config.client_mac, 6);
348 if (client_config.clientid)
349 udhcp_add_binary_option(packet, client_config.clientid);
350 if (client_config.hostname)
351 udhcp_add_binary_option(packet, client_config.hostname);
352 if (client_config.fqdn)
353 udhcp_add_binary_option(packet, client_config.fqdn);
354 if (type != DHCPDECLINE
355 && type != DHCPRELEASE
356 && client_config.vendorclass
358 udhcp_add_binary_option(packet, client_config.vendorclass);
362 static void add_client_options(struct dhcp_packet *packet)
364 /* Add a "param req" option with the list of options we'd like to have
365 * from stubborn DHCP servers. Pull the data from the struct in common.c.
366 * No bounds checking because it goes towards the head of the packet. */
368 int end = udhcp_end_option(packet->options);
371 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
372 if (( (dhcp_optflags[i].flags & OPTION_REQ)
373 && !client_config.no_default_options
375 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
377 packet->options[end + OPT_DATA + len] = c;
382 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
383 packet->options[end + OPT_LEN] = len;
384 packet->options[end + OPT_DATA + len] = DHCP_END;
387 /* Add -x options if any */
389 struct option_set *curr = client_config.options;
391 udhcp_add_binary_option(packet, curr->data);
394 // if (client_config.sname)
395 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
396 // if (client_config.boot_file)
397 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
402 * 4.4.4 Use of broadcast and unicast
404 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
405 * messages, unless the client knows the address of a DHCP server.
406 * The client unicasts DHCPRELEASE messages to the server. Because
407 * the client is declining the use of the IP address supplied by the server,
408 * the client broadcasts DHCPDECLINE messages.
410 * When the DHCP client knows the address of a DHCP server, in either
411 * INIT or REBOOTING state, the client may use that address
412 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
413 * The client may also use unicast to send DHCPINFORM messages
414 * to a known DHCP server. If the client receives no response to DHCP
415 * messages sent to the IP address of a known DHCP server, the DHCP
416 * client reverts to using the IP broadcast address.
419 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
421 return udhcp_send_raw_packet(packet,
422 /*src*/ INADDR_ANY, CLIENT_PORT,
423 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
424 client_config.ifindex);
427 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
428 static int send_discover(uint32_t xid, uint32_t requested)
430 struct dhcp_packet packet;
432 init_packet(&packet, DHCPDISCOVER);
435 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
436 /* Explicitly saying that we want RFC-compliant packets helps
437 * some buggy DHCP servers to NOT send bigger packets */
438 udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576));
439 add_client_options(&packet);
441 bb_info_msg("Sending discover...");
442 return raw_bcast_from_client_config_ifindex(&packet);
445 /* Broadcast a DHCP request message */
446 /* RFC 2131 3.1 paragraph 3:
447 * "The client _broadcasts_ a DHCPREQUEST message..."
449 static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
451 struct dhcp_packet packet;
454 init_packet(&packet, DHCPREQUEST);
456 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
457 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
458 add_client_options(&packet);
460 addr.s_addr = requested;
461 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
462 return raw_bcast_from_client_config_ifindex(&packet);
465 /* Unicast or broadcast a DHCP renew message */
466 static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
468 struct dhcp_packet packet;
470 init_packet(&packet, DHCPREQUEST);
472 packet.ciaddr = ciaddr;
473 add_client_options(&packet);
475 bb_info_msg("Sending renew...");
477 return udhcp_send_kernel_packet(&packet,
479 server, SERVER_PORT);
480 return raw_bcast_from_client_config_ifindex(&packet);
483 #if ENABLE_FEATURE_UDHCPC_ARPING
484 /* Broadcast a DHCP decline message */
485 static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
487 struct dhcp_packet packet;
489 init_packet(&packet, DHCPDECLINE);
491 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
492 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
494 bb_info_msg("Sending decline...");
495 return raw_bcast_from_client_config_ifindex(&packet);
499 /* Unicast a DHCP release message */
500 static int send_release(uint32_t server, uint32_t ciaddr)
502 struct dhcp_packet packet;
504 init_packet(&packet, DHCPRELEASE);
505 packet.xid = random_xid();
506 packet.ciaddr = ciaddr;
508 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
510 bb_info_msg("Sending release...");
511 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
514 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
515 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
518 struct ip_udp_dhcp_packet packet;
521 memset(&packet, 0, sizeof(packet));
522 bytes = safe_read(fd, &packet, sizeof(packet));
524 log1("Packet read error, ignoring");
525 /* NB: possible down interface, etc. Caller should pause. */
526 return bytes; /* returns -1 */
529 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
530 log1("Packet is too short, ignoring");
534 if (bytes < ntohs(packet.ip.tot_len)) {
535 /* packet is bigger than sizeof(packet), we did partial read */
536 log1("Oversized packet, ignoring");
540 /* ignore any extra garbage bytes */
541 bytes = ntohs(packet.ip.tot_len);
543 /* make sure its the right packet for us, and that it passes sanity checks */
544 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
545 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
546 || packet.udp.dest != htons(CLIENT_PORT)
547 /* || bytes > (int) sizeof(packet) - can't happen */
548 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
550 log1("Unrelated/bogus packet, ignoring");
554 /* verify IP checksum */
555 check = packet.ip.check;
557 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
558 log1("Bad IP header checksum, ignoring");
562 /* verify UDP checksum. IP header has to be modified for this */
563 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
564 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
565 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
566 check = packet.udp.check;
567 packet.udp.check = 0;
568 if (check && check != udhcp_checksum(&packet, bytes)) {
569 log1("Packet with bad UDP checksum received, ignoring");
573 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
575 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
576 bb_info_msg("Packet with bad magic, ignoring");
579 log1("Got valid DHCP packet");
580 udhcp_dump_packet(dhcp_pkt);
581 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
587 static int sockfd = -1;
589 #define LISTEN_NONE 0
590 #define LISTEN_KERNEL 1
592 static smallint listen_mode;
594 /* initial state: (re)start DHCP negotiation */
595 #define INIT_SELECTING 0
596 /* discover was sent, DHCPOFFER reply received */
598 /* select/renew was sent, DHCPACK reply received */
600 /* half of lease passed, want to renew it by sending unicast renew requests */
602 /* renew requests were not answered, lease is almost over, send broadcast renew */
604 /* manually requested renew (SIGUSR1) */
605 #define RENEW_REQUESTED 5
606 /* release, possibly manually requested (SIGUSR2) */
608 static smallint state;
610 static int udhcp_raw_socket(int ifindex)
613 struct sockaddr_ll sock;
618 * I've selected not to see LL header, so BPF doesn't see it, too.
619 * The filter may also pass non-IP and non-ARP packets, but we do
620 * a more complete check when receiving the message in userspace.
622 * and filter shamelessly stolen from:
624 * http://www.flamewarmaster.de/software/dhcpclient/
626 * There are a few other interesting ideas on that page (look under
627 * "Motivation"). Use of netlink events is most interesting. Think
628 * of various network servers listening for events and reconfiguring.
629 * That would obsolete sending HUP signals and/or make use of restarts.
631 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
634 * TODO: make conditional?
636 #define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
637 static const struct sock_filter filter_instr[] = {
639 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
640 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
641 /* ugly check for arp on ethernet-like and IPv4 */
642 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
643 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
645 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
646 /* check udp source and destination ports */
647 BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
648 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */
650 BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
651 BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
653 static const struct sock_fprog filter_prog = {
654 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
655 /* casting const away: */
656 .filter = (struct sock_filter *) filter_instr,
659 log1("Opening raw socket on ifindex %d", ifindex); //log2?
661 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
662 log1("Got raw socket fd %d", fd); //log2?
664 if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
665 /* Use only if standard ports are in use */
666 /* Ignoring error (kernel may lack support for this) */
667 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
668 sizeof(filter_prog)) >= 0)
669 log1("Attached filter to raw socket fd %d", fd); // log?
672 sock.sll_family = AF_PACKET;
673 sock.sll_protocol = htons(ETH_P_IP);
674 sock.sll_ifindex = ifindex;
675 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
676 log1("Created raw socket");
681 static void change_listen_mode(int new_mode)
683 log1("Entering listen mode: %s",
684 new_mode != LISTEN_NONE
685 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
689 listen_mode = new_mode;
694 if (new_mode == LISTEN_KERNEL)
695 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
696 else if (new_mode != LISTEN_NONE)
697 sockfd = udhcp_raw_socket(client_config.ifindex);
698 /* else LISTEN_NONE: sockfd stays closed */
701 static void perform_renew(void)
703 bb_info_msg("Performing a DHCP renew");
706 change_listen_mode(LISTEN_KERNEL);
709 state = RENEW_REQUESTED;
711 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
712 udhcp_run_script(NULL, "deconfig");
715 change_listen_mode(LISTEN_RAW);
716 state = INIT_SELECTING;
723 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
725 char buffer[sizeof("255.255.255.255")];
726 struct in_addr temp_addr;
728 /* send release packet */
729 if (state == BOUND || state == RENEWING || state == REBINDING) {
730 temp_addr.s_addr = server_addr;
731 strcpy(buffer, inet_ntoa(temp_addr));
732 temp_addr.s_addr = requested_ip;
733 bb_info_msg("Unicasting a release of %s to %s",
734 inet_ntoa(temp_addr), buffer);
735 send_release(server_addr, requested_ip); /* unicast */
736 udhcp_run_script(NULL, "deconfig");
738 bb_info_msg("Entering released state");
740 change_listen_mode(LISTEN_NONE);
744 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
747 int len = strnlen(str, 255);
748 storage = xzalloc(len + extra + OPT_DATA);
749 storage[OPT_CODE] = code;
750 storage[OPT_LEN] = len + extra;
751 memcpy(storage + extra + OPT_DATA, str, len);
756 static void client_background(void)
759 logmode &= ~LOGMODE_STDIO;
760 /* rewrite pidfile, as our pid is different now */
761 write_pidfile(client_config.pidfile);
765 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
766 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
768 uint8_t *temp, *message;
769 const char *str_c, *str_V, *str_h, *str_F, *str_r;
770 IF_FEATURE_UDHCP_PORT(char *str_P;)
771 llist_t *list_O = NULL;
772 llist_t *list_x = NULL;
773 int tryagain_timeout = 20;
774 int discover_timeout = 3;
775 int discover_retries = 3;
776 uint32_t server_addr = server_addr; /* for compiler */
777 uint32_t requested_ip = 0;
779 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
781 int timeout; /* must be signed */
782 unsigned already_waited_sec;
787 struct dhcp_packet packet;
791 static const char udhcpc_longopts[] ALIGN1 =
792 "clientid\0" Required_argument "c"
793 "clientid-none\0" No_argument "C"
794 "vendorclass\0" Required_argument "V"
795 "hostname\0" Required_argument "H"
796 "fqdn\0" Required_argument "F"
797 "interface\0" Required_argument "i"
798 "now\0" No_argument "n"
799 "pidfile\0" Required_argument "p"
800 "quit\0" No_argument "q"
801 "release\0" No_argument "R"
802 "request\0" Required_argument "r"
803 "script\0" Required_argument "s"
804 "timeout\0" Required_argument "T"
805 "version\0" No_argument "v"
806 "retries\0" Required_argument "t"
807 "tryagain\0" Required_argument "A"
808 "syslog\0" No_argument "S"
809 "request-option\0" Required_argument "O"
810 "no-default-options\0" No_argument "o"
811 "foreground\0" No_argument "f"
812 "background\0" No_argument "b"
813 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
814 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
839 /* The rest has variable bit positions, need to be clever */
841 USE_FOR_MMU( OPTBIT_b,)
842 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
843 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
844 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
845 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
846 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
849 /* Default options. */
850 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
851 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
852 client_config.interface = "eth0";
853 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
854 str_V = "udhcp "BB_VER;
856 /* Parse command line */
857 /* Cc: mutually exclusive; O,x: list; -T,-t,-A take numeric param */
858 opt_complementary = "c--C:C--c:O::x::T+:t+:A+"
859 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
863 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
864 opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:f"
866 IF_FEATURE_UDHCPC_ARPING("a")
867 IF_FEATURE_UDHCP_PORT("P:")
869 , &str_c, &str_V, &str_h, &str_h, &str_F
870 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
871 , &client_config.script /* s */
872 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
875 IF_FEATURE_UDHCP_PORT(, &str_P)
876 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
880 if (opt & (OPT_h|OPT_H))
881 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
883 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
884 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
885 /* Flag bits: 0000NEOS
886 * S: 1 = Client requests server to update A RR in DNS as well as PTR
887 * O: 1 = Server indicates to client that DNS has been updated regardless
888 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
889 * not "host.domain.com". Format 0 is obsolete.
890 * N: 1 = Client requests server to not update DNS (S must be 0 then)
891 * Two [0] bytes which follow are deprecated and must be 0.
893 client_config.fqdn[OPT_DATA + 0] = 0x1;
894 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
895 /*client_config.fqdn[OPT_DATA + 2] = 0; */
898 requested_ip = inet_addr(str_r);
899 #if ENABLE_FEATURE_UDHCP_PORT
901 CLIENT_PORT = xatou16(str_P);
902 SERVER_PORT = CLIENT_PORT - 1;
906 client_config.no_default_options = 1;
908 char *optstr = llist_pop(&list_O);
909 unsigned n = udhcp_option_idx(optstr);
910 n = dhcp_optflags[n].code;
911 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
914 char *optstr = llist_pop(&list_x);
915 char *colon = strchr(optstr, ':');
918 /* now it looks similar to udhcpd's config file line:
919 * "optname optval", using the common routine: */
920 udhcp_str2optset(optstr, &client_config.options);
923 if (udhcp_read_interface(client_config.interface,
924 &client_config.ifindex,
926 client_config.client_mac)
932 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
933 } else if (!(opt & OPT_C)) {
934 /* not set and not suppressed, set the default client ID */
935 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
936 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
937 memcpy(client_config.clientid + OPT_DATA+1, client_config.client_mac, 6);
939 if (str_V[0] != '\0')
940 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
942 /* on NOMMU reexec (i.e., background) early */
943 if (!(opt & OPT_f)) {
944 bb_daemonize_or_rexec(0 /* flags */, argv);
945 logmode = LOGMODE_NONE;
949 openlog(applet_name, LOG_PID, LOG_DAEMON);
950 logmode |= LOGMODE_SYSLOG;
953 /* Make sure fd 0,1,2 are open */
955 /* Equivalent of doing a fflush after every \n */
958 write_pidfile(client_config.pidfile);
959 /* Goes to stdout (unless NOMMU) and possibly syslog */
960 bb_info_msg("%s (v"BB_VER") started", applet_name);
961 /* Set up the signal pipe */
963 /* We want random_xid to be random... */
964 srand(monotonic_us());
966 state = INIT_SELECTING;
967 udhcp_run_script(NULL, "deconfig");
968 change_listen_mode(LISTEN_RAW);
971 already_waited_sec = 0;
973 /* Main event loop. select() waits on signal pipe and possibly
975 * "continue" statements in code below jump to the top of the loop.
978 /* silence "uninitialized!" warning */
979 unsigned timestamp_before_wait = timestamp_before_wait;
981 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
983 /* Was opening raw or udp socket here
984 * if (listen_mode != LISTEN_NONE && sockfd < 0),
985 * but on fast network renew responses return faster
986 * than we open sockets. Thus this code is moved
987 * to change_listen_mode(). Thus we open listen socket
988 * BEFORE we send renew request (see "case BOUND:"). */
990 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
992 tv.tv_sec = timeout - already_waited_sec;
995 /* If we already timed out, fall through with retval = 0, else... */
996 if ((int)tv.tv_sec > 0) {
997 timestamp_before_wait = (unsigned)monotonic_sec();
998 log1("Waiting on select...");
999 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1001 /* EINTR? A signal was caught, don't panic */
1002 if (errno == EINTR) {
1003 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1006 /* Else: an error occured, panic! */
1007 bb_perror_msg_and_die("select");
1011 /* If timeout dropped to zero, time to become active:
1012 * resend discover/renew/whatever
1015 /* We will restart the wait in any case */
1016 already_waited_sec = 0;
1019 case INIT_SELECTING:
1020 if (packet_num < discover_retries) {
1021 if (packet_num == 0)
1024 send_discover(xid, requested_ip);
1025 timeout = discover_timeout;
1030 udhcp_run_script(NULL, "leasefail");
1031 #if BB_MMU /* -b is not supported on NOMMU */
1032 if (opt & OPT_b) { /* background if no lease */
1033 bb_info_msg("No lease, forking to background");
1034 client_background();
1035 /* do not background again! */
1036 opt = ((opt & ~OPT_b) | OPT_f);
1039 if (opt & OPT_n) { /* abort if no lease */
1040 bb_info_msg("No lease, failing");
1044 /* wait before trying again */
1045 timeout = tryagain_timeout;
1049 if (packet_num < discover_retries) {
1050 /* send broadcast select packet */
1051 send_select(xid, server_addr, requested_ip);
1052 timeout = discover_timeout;
1056 /* Timed out, go back to init state.
1057 * "discover...select...discover..." loops
1058 * were seen in the wild. Treat them similarly
1059 * to "no response to discover" case */
1060 change_listen_mode(LISTEN_RAW);
1061 state = INIT_SELECTING;
1064 /* 1/2 lease passed, enter renewing state */
1066 change_listen_mode(LISTEN_KERNEL);
1067 log1("Entering renew state");
1068 /* fall right through */
1069 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1070 case_RENEW_REQUESTED:
1073 /* send an unicast renew request */
1074 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1075 * a new UDP socket for sending inside send_renew.
1076 * I hazard to guess existing listening socket
1077 * is somehow conflicting with it, but why is it
1078 * not deterministic then?! Strange.
1079 * Anyway, it does recover by eventually failing through
1080 * into INIT_SELECTING state.
1082 send_renew(xid, server_addr, requested_ip);
1086 /* Timed out, enter rebinding state */
1087 log1("Entering rebinding state");
1089 /* fall right through */
1091 /* Switch to bcast receive */
1092 change_listen_mode(LISTEN_RAW);
1093 /* Lease is *really* about to run out,
1094 * try to find DHCP server using broadcast */
1096 /* send a broadcast renew request */
1097 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1101 /* Timed out, enter init state */
1102 bb_info_msg("Lease lost, entering init state");
1103 udhcp_run_script(NULL, "deconfig");
1104 state = INIT_SELECTING;
1105 /*timeout = 0; - already is */
1108 /* case RELEASED: */
1110 /* yah, I know, *you* say it would never happen */
1112 continue; /* back to main loop */
1113 } /* if select timed out */
1115 /* select() didn't timeout, something happened */
1117 /* Is it a signal? */
1118 /* note: udhcp_sp_read checks FD_ISSET before reading */
1119 switch (udhcp_sp_read(&rfds)) {
1122 if (state == RENEW_REQUESTED)
1123 goto case_RENEW_REQUESTED;
1124 /* Start things over */
1126 /* Kill any timeouts, user wants this to hurry along */
1130 perform_release(requested_ip, server_addr);
1134 bb_info_msg("Received SIGTERM");
1135 if (opt & OPT_R) /* release on quit */
1136 perform_release(requested_ip, server_addr);
1140 /* Is it a packet? */
1141 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1147 /* A packet is ready, read it */
1148 if (listen_mode == LISTEN_KERNEL)
1149 len = udhcp_recv_kernel_packet(&packet, sockfd);
1151 len = udhcp_recv_raw_packet(&packet, sockfd);
1153 /* Error is severe, reopen socket */
1154 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1155 sleep(discover_timeout); /* 3 seconds by default */
1156 change_listen_mode(listen_mode); /* just close and reopen */
1158 /* If this packet will turn out to be unrelated/bogus,
1159 * we will go back and wait for next one.
1160 * Be sure timeout is properly decreased. */
1161 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1166 if (packet.xid != xid) {
1167 log1("xid %x (our is %x), ignoring packet",
1168 (unsigned)packet.xid, (unsigned)xid);
1172 /* Ignore packets that aren't for us */
1173 if (packet.hlen != 6
1174 || memcmp(packet.chaddr, client_config.client_mac, 6)
1176 //FIXME: need to also check that last 10 bytes are zero
1177 log1("chaddr does not match, ignoring packet"); // log2?
1181 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1182 if (message == NULL) {
1183 bb_error_msg("no message type option, ignoring packet");
1188 case INIT_SELECTING:
1189 /* Must be a DHCPOFFER to one of our xid's */
1190 if (*message == DHCPOFFER) {
1191 /* TODO: why we don't just fetch server's IP from IP header? */
1192 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1194 bb_error_msg("no server ID in message");
1196 /* still selecting - this server looks bad */
1198 /* it IS unaligned sometimes, don't "optimize" */
1199 move_from_unaligned32(server_addr, temp);
1201 requested_ip = packet.yiaddr;
1203 /* enter requesting state */
1207 already_waited_sec = 0;
1212 case RENEW_REQUESTED:
1214 if (*message == DHCPACK) {
1215 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1217 bb_error_msg("no lease time with ACK, using 1 hour lease");
1218 lease_seconds = 60 * 60;
1220 /* it IS unaligned sometimes, don't "optimize" */
1221 move_from_unaligned32(lease_seconds, temp);
1222 lease_seconds = ntohl(lease_seconds);
1223 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1224 if (lease_seconds < 10) /* and not too small */
1227 #if ENABLE_FEATURE_UDHCPC_ARPING
1229 /* RFC 2131 3.1 paragraph 5:
1230 * "The client receives the DHCPACK message with configuration
1231 * parameters. The client SHOULD perform a final check on the
1232 * parameters (e.g., ARP for allocated network address), and notes
1233 * the duration of the lease specified in the DHCPACK message. At this
1234 * point, the client is configured. If the client detects that the
1235 * address is already in use (e.g., through the use of ARP),
1236 * the client MUST send a DHCPDECLINE message to the server and restarts
1237 * the configuration process..." */
1238 if (!arpping(packet.yiaddr,
1241 client_config.client_mac,
1242 client_config.interface)
1244 bb_info_msg("Offered address is in use "
1245 "(got ARP reply), declining");
1246 send_decline(xid, server_addr, packet.yiaddr);
1248 if (state != REQUESTING)
1249 udhcp_run_script(NULL, "deconfig");
1250 change_listen_mode(LISTEN_RAW);
1251 state = INIT_SELECTING;
1253 timeout = tryagain_timeout;
1255 already_waited_sec = 0;
1256 continue; /* back to main loop */
1260 /* enter bound state */
1261 timeout = lease_seconds / 2;
1263 struct in_addr temp_addr;
1264 temp_addr.s_addr = packet.yiaddr;
1265 bb_info_msg("Lease of %s obtained, lease time %u",
1266 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1268 requested_ip = packet.yiaddr;
1269 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1272 change_listen_mode(LISTEN_NONE);
1273 if (opt & OPT_q) { /* quit after lease */
1274 if (opt & OPT_R) /* release on quit */
1275 perform_release(requested_ip, server_addr);
1278 /* future renew failures should not exit (JM) */
1280 #if BB_MMU /* NOMMU case backgrounded earlier */
1281 if (!(opt & OPT_f)) {
1282 client_background();
1283 /* do not background again! */
1284 opt = ((opt & ~OPT_b) | OPT_f);
1287 already_waited_sec = 0;
1288 continue; /* back to main loop */
1290 if (*message == DHCPNAK) {
1291 /* return to init state */
1292 bb_info_msg("Received DHCP NAK");
1293 udhcp_run_script(&packet, "nak");
1294 if (state != REQUESTING)
1295 udhcp_run_script(NULL, "deconfig");
1296 change_listen_mode(LISTEN_RAW);
1297 sleep(3); /* avoid excessive network traffic */
1298 state = INIT_SELECTING;
1302 already_waited_sec = 0;
1305 /* case BOUND: - ignore all packets */
1306 /* case RELEASED: - ignore all packets */
1308 /* back to main loop */
1309 } /* for (;;) - main loop ends */
1314 /*if (client_config.pidfile) - remove_pidfile has its own check */
1315 remove_pidfile(client_config.pidfile);