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];
93 type = optflag->flags & OPTION_TYPE_MASK;
94 optlen = dhcp_option_lengths[type];
95 upper_length = len_of_option_as_string[type] * ((unsigned)len / (unsigned)optlen);
97 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
98 dest += sprintf(ret, "%s=", opt_name);
100 while (len >= optlen) {
105 dest += sprint_nip(dest, "", option);
110 dest += sprint_nip(dest, "", option + ip_ofs);
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);
221 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
222 // Should we bail out/warn if we see multi-ip option which is
223 // not allowed to be such (for example, DHCP_BROADCAST)? -
224 if (len <= 0 /* || !(optflag->flags & OPTION_LIST) */)
232 /* put all the parameters into the environment */
233 static char **fill_envp(struct dhcp_packet *packet)
238 const char *opt_name;
240 uint8_t overload = 0;
242 /* We need 6 elements for:
244 * "ip=N.N.N.N" from packet->yiaddr
245 * "siaddr=IP" from packet->siaddr_nip (unless 0)
246 * "boot_file=FILE" from packet->file (unless overloaded)
247 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
251 /* +1 element for each option, +2 for subnet option: */
253 for (i = 0; dhcp_optflags[i].code; i++) {
254 if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
255 if (dhcp_optflags[i].code == DHCP_SUBNET)
256 envc++; /* for mton */
260 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
264 curr = envp = xzalloc(sizeof(char *) * envc);
266 *curr = xasprintf("interface=%s", client_config.interface);
272 *curr = xmalloc(sizeof("ip=255.255.255.255"));
273 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
276 opt_name = dhcp_option_strings;
279 temp = udhcp_get_option(packet, dhcp_optflags[i].code);
282 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
284 if (dhcp_optflags[i].code == DHCP_SUBNET) {
285 /* Subnet option: make things like "$ip/$mask" possible */
287 move_from_unaligned32(subnet, temp);
288 *curr = xasprintf("mask=%d", mton(subnet));
292 opt_name += strlen(opt_name) + 1;
295 if (packet->siaddr_nip) {
296 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
297 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
300 if (!(overload & FILE_FIELD) && packet->file[0]) {
301 /* watch out for invalid packets */
302 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
305 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
306 /* watch out for invalid packets */
307 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
313 /* Call a script with a par file and env vars */
314 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
319 if (client_config.script == NULL)
322 envp = fill_envp(packet);
325 log1("Executing %s %s", client_config.script, name);
326 argv[0] = (char*) client_config.script;
327 argv[1] = (char*) name;
329 spawn_and_wait(argv);
331 for (curr = envp; *curr; curr++) {
333 bb_unsetenv_and_free(*curr);
339 /*** Sending/receiving packets ***/
341 static ALWAYS_INLINE uint32_t random_xid(void)
346 /* Initialize the packet with the proper defaults */
347 static void init_packet(struct dhcp_packet *packet, char type)
349 udhcp_init_header(packet, type);
350 memcpy(packet->chaddr, client_config.client_mac, 6);
351 if (client_config.clientid)
352 udhcp_add_binary_option(packet, client_config.clientid);
353 if (client_config.hostname)
354 udhcp_add_binary_option(packet, client_config.hostname);
355 if (client_config.fqdn)
356 udhcp_add_binary_option(packet, client_config.fqdn);
357 if (type != DHCPDECLINE
358 && type != DHCPRELEASE
359 && client_config.vendorclass
361 udhcp_add_binary_option(packet, client_config.vendorclass);
365 static void add_client_options(struct dhcp_packet *packet)
367 /* Add a "param req" option with the list of options we'd like to have
368 * from stubborn DHCP servers. Pull the data from the struct in common.c.
369 * No bounds checking because it goes towards the head of the packet. */
371 int end = udhcp_end_option(packet->options);
374 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
375 if (( (dhcp_optflags[i].flags & OPTION_REQ)
376 && !client_config.no_default_options
378 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
380 packet->options[end + OPT_DATA + len] = c;
385 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
386 packet->options[end + OPT_LEN] = len;
387 packet->options[end + OPT_DATA + len] = DHCP_END;
390 /* Add -x options if any */
392 struct option_set *curr = client_config.options;
394 udhcp_add_binary_option(packet, curr->data);
397 // if (client_config.sname)
398 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
399 // if (client_config.boot_file)
400 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
405 * 4.4.4 Use of broadcast and unicast
407 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
408 * messages, unless the client knows the address of a DHCP server.
409 * The client unicasts DHCPRELEASE messages to the server. Because
410 * the client is declining the use of the IP address supplied by the server,
411 * the client broadcasts DHCPDECLINE messages.
413 * When the DHCP client knows the address of a DHCP server, in either
414 * INIT or REBOOTING state, the client may use that address
415 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
416 * The client may also use unicast to send DHCPINFORM messages
417 * to a known DHCP server. If the client receives no response to DHCP
418 * messages sent to the IP address of a known DHCP server, the DHCP
419 * client reverts to using the IP broadcast address.
422 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
424 return udhcp_send_raw_packet(packet,
425 /*src*/ INADDR_ANY, CLIENT_PORT,
426 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
427 client_config.ifindex);
430 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
431 static int send_discover(uint32_t xid, uint32_t requested)
433 struct dhcp_packet packet;
435 init_packet(&packet, DHCPDISCOVER);
438 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
439 /* Explicitly saying that we want RFC-compliant packets helps
440 * some buggy DHCP servers to NOT send bigger packets */
441 udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576));
442 add_client_options(&packet);
444 bb_info_msg("Sending discover...");
445 return raw_bcast_from_client_config_ifindex(&packet);
448 /* Broadcast a DHCP request message */
449 /* RFC 2131 3.1 paragraph 3:
450 * "The client _broadcasts_ a DHCPREQUEST message..."
452 static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
454 struct dhcp_packet packet;
457 init_packet(&packet, DHCPREQUEST);
459 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
460 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
461 add_client_options(&packet);
463 addr.s_addr = requested;
464 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
465 return raw_bcast_from_client_config_ifindex(&packet);
468 /* Unicast or broadcast a DHCP renew message */
469 static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
471 struct dhcp_packet packet;
473 init_packet(&packet, DHCPREQUEST);
475 packet.ciaddr = ciaddr;
476 add_client_options(&packet);
478 bb_info_msg("Sending renew...");
480 return udhcp_send_kernel_packet(&packet,
482 server, SERVER_PORT);
483 return raw_bcast_from_client_config_ifindex(&packet);
486 #if ENABLE_FEATURE_UDHCPC_ARPING
487 /* Broadcast a DHCP decline message */
488 static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
490 struct dhcp_packet packet;
492 init_packet(&packet, DHCPDECLINE);
494 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
495 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
497 bb_info_msg("Sending decline...");
498 return raw_bcast_from_client_config_ifindex(&packet);
502 /* Unicast a DHCP release message */
503 static int send_release(uint32_t server, uint32_t ciaddr)
505 struct dhcp_packet packet;
507 init_packet(&packet, DHCPRELEASE);
508 packet.xid = random_xid();
509 packet.ciaddr = ciaddr;
511 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
513 bb_info_msg("Sending release...");
514 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
517 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
518 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
521 struct ip_udp_dhcp_packet packet;
524 memset(&packet, 0, sizeof(packet));
525 bytes = safe_read(fd, &packet, sizeof(packet));
527 log1("Packet read error, ignoring");
528 /* NB: possible down interface, etc. Caller should pause. */
529 return bytes; /* returns -1 */
532 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
533 log1("Packet is too short, ignoring");
537 if (bytes < ntohs(packet.ip.tot_len)) {
538 /* packet is bigger than sizeof(packet), we did partial read */
539 log1("Oversized packet, ignoring");
543 /* ignore any extra garbage bytes */
544 bytes = ntohs(packet.ip.tot_len);
546 /* make sure its the right packet for us, and that it passes sanity checks */
547 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
548 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
549 || packet.udp.dest != htons(CLIENT_PORT)
550 /* || bytes > (int) sizeof(packet) - can't happen */
551 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
553 log1("Unrelated/bogus packet, ignoring");
557 /* verify IP checksum */
558 check = packet.ip.check;
560 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
561 log1("Bad IP header checksum, ignoring");
565 /* verify UDP checksum. IP header has to be modified for this */
566 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
567 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
568 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
569 check = packet.udp.check;
570 packet.udp.check = 0;
571 if (check && check != udhcp_checksum(&packet, bytes)) {
572 log1("Packet with bad UDP checksum received, ignoring");
576 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
578 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
579 bb_info_msg("Packet with bad magic, ignoring");
582 log1("Got valid DHCP packet");
583 udhcp_dump_packet(dhcp_pkt);
584 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
590 static int sockfd = -1;
592 #define LISTEN_NONE 0
593 #define LISTEN_KERNEL 1
595 static smallint listen_mode;
597 /* initial state: (re)start DHCP negotiation */
598 #define INIT_SELECTING 0
599 /* discover was sent, DHCPOFFER reply received */
601 /* select/renew was sent, DHCPACK reply received */
603 /* half of lease passed, want to renew it by sending unicast renew requests */
605 /* renew requests were not answered, lease is almost over, send broadcast renew */
607 /* manually requested renew (SIGUSR1) */
608 #define RENEW_REQUESTED 5
609 /* release, possibly manually requested (SIGUSR2) */
611 static smallint state;
613 static int udhcp_raw_socket(int ifindex)
616 struct sockaddr_ll sock;
621 * I've selected not to see LL header, so BPF doesn't see it, too.
622 * The filter may also pass non-IP and non-ARP packets, but we do
623 * a more complete check when receiving the message in userspace.
625 * and filter shamelessly stolen from:
627 * http://www.flamewarmaster.de/software/dhcpclient/
629 * There are a few other interesting ideas on that page (look under
630 * "Motivation"). Use of netlink events is most interesting. Think
631 * of various network servers listening for events and reconfiguring.
632 * That would obsolete sending HUP signals and/or make use of restarts.
634 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
637 * TODO: make conditional?
639 #define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
640 static const struct sock_filter filter_instr[] = {
642 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
643 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
644 /* ugly check for arp on ethernet-like and IPv4 */
645 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
646 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
648 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
649 /* check udp source and destination ports */
650 BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
651 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */
653 BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
654 BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
656 static const struct sock_fprog filter_prog = {
657 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
658 /* casting const away: */
659 .filter = (struct sock_filter *) filter_instr,
662 log1("Opening raw socket on ifindex %d", ifindex); //log2?
664 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
665 log1("Got raw socket fd %d", fd); //log2?
667 if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
668 /* Use only if standard ports are in use */
669 /* Ignoring error (kernel may lack support for this) */
670 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
671 sizeof(filter_prog)) >= 0)
672 log1("Attached filter to raw socket fd %d", fd); // log?
675 sock.sll_family = AF_PACKET;
676 sock.sll_protocol = htons(ETH_P_IP);
677 sock.sll_ifindex = ifindex;
678 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
679 log1("Created raw socket");
684 static void change_listen_mode(int new_mode)
686 log1("Entering listen mode: %s",
687 new_mode != LISTEN_NONE
688 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
692 listen_mode = new_mode;
697 if (new_mode == LISTEN_KERNEL)
698 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
699 else if (new_mode != LISTEN_NONE)
700 sockfd = udhcp_raw_socket(client_config.ifindex);
701 /* else LISTEN_NONE: sockfd stays closed */
704 static void perform_renew(void)
706 bb_info_msg("Performing a DHCP renew");
709 change_listen_mode(LISTEN_KERNEL);
712 state = RENEW_REQUESTED;
714 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
715 udhcp_run_script(NULL, "deconfig");
718 change_listen_mode(LISTEN_RAW);
719 state = INIT_SELECTING;
726 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
728 char buffer[sizeof("255.255.255.255")];
729 struct in_addr temp_addr;
731 /* send release packet */
732 if (state == BOUND || state == RENEWING || state == REBINDING) {
733 temp_addr.s_addr = server_addr;
734 strcpy(buffer, inet_ntoa(temp_addr));
735 temp_addr.s_addr = requested_ip;
736 bb_info_msg("Unicasting a release of %s to %s",
737 inet_ntoa(temp_addr), buffer);
738 send_release(server_addr, requested_ip); /* unicast */
739 udhcp_run_script(NULL, "deconfig");
741 bb_info_msg("Entering released state");
743 change_listen_mode(LISTEN_NONE);
747 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
750 int len = strnlen(str, 255);
751 storage = xzalloc(len + extra + OPT_DATA);
752 storage[OPT_CODE] = code;
753 storage[OPT_LEN] = len + extra;
754 memcpy(storage + extra + OPT_DATA, str, len);
759 static void client_background(void)
762 logmode &= ~LOGMODE_STDIO;
763 /* rewrite pidfile, as our pid is different now */
764 write_pidfile(client_config.pidfile);
768 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
769 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
771 //usage:# define IF_UDHCP_VERBOSE(...)
773 //usage:#define udhcpc_trivial_usage
774 //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCR] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
775 //usage: " [-H HOSTNAME] [-c CID] [-V VENDOR] [-O DHCP_OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
776 //usage:#define udhcpc_full_usage "\n"
777 //usage: IF_LONG_OPTS(
778 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
779 //usage: "\n -p,--pidfile FILE Create pidfile"
780 //usage: "\n -r,--request IP IP address to request"
781 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
782 //usage: "\n -t,--retries N Send up to N discover packets"
783 //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
784 //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
785 //usage: "\n -f,--foreground Run in foreground"
786 //usage: USE_FOR_MMU(
787 //usage: "\n -b,--background Background if lease is not obtained"
789 //usage: "\n -S,--syslog Log to syslog too"
790 //usage: "\n -n,--now Exit if lease is not obtained"
791 //usage: "\n -q,--quit Exit after obtaining lease"
792 //usage: "\n -R,--release Release IP on exit"
793 //usage: IF_FEATURE_UDHCP_PORT(
794 //usage: "\n -P,--client-port N Use port N (default 68)"
796 //usage: IF_FEATURE_UDHCPC_ARPING(
797 //usage: "\n -a,--arping Use arping to validate offered address"
799 //usage: "\n -O,--request-option OPT Request DHCP option OPT (cumulative)"
800 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
801 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
802 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
803 //usage: "\n -H,-h,--hostname NAME Send NAME as client hostname (default none)"
804 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
805 //usage: "\n -c,--clientid CLIENTID Client identifier (default own MAC)"
806 //usage: "\n -C,--clientid-none Don't send client identifier"
807 //usage: IF_UDHCP_VERBOSE(
808 //usage: "\n -v Verbose"
811 //usage: IF_NOT_LONG_OPTS(
812 //usage: "\n -i IFACE Interface to use (default eth0)"
813 //usage: "\n -p FILE Create pidfile"
814 //usage: "\n -r IP IP address to request"
815 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
816 //usage: "\n -t N Send up to N discover packets"
817 //usage: "\n -T N Pause between packets (default 3 seconds)"
818 //usage: "\n -A N Wait N seconds (default 20) after failure"
819 //usage: "\n -x OPT:VAL Include option OPT in sent packets"
820 //usage: "\n -O OPT Request DHCP option OPT (cumulative)"
821 //usage: "\n -o Don't request any options (unless -O is given)"
822 //usage: "\n -f Run in foreground"
823 //usage: USE_FOR_MMU(
824 //usage: "\n -b Background if lease is not obtained"
826 //usage: "\n -S Log to syslog too"
827 //usage: "\n -n Exit if lease is not obtained"
828 //usage: "\n -q Exit after obtaining lease"
829 //usage: "\n -R Release IP on exit"
830 //usage: IF_FEATURE_UDHCP_PORT(
831 //usage: "\n -P N Use port N (default 68)"
833 //usage: IF_FEATURE_UDHCPC_ARPING(
834 //usage: "\n -a Use arping to validate offered address"
836 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
837 //usage: "\n -H,-h NAME Send NAME as client hostname (default none)"
838 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
839 //usage: "\n -c CLIENTID Client identifier (default own MAC)"
840 //usage: "\n -C Don't send client identifier"
841 //usage: IF_UDHCP_VERBOSE(
842 //usage: "\n -v Verbose"
846 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
847 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
849 uint8_t *temp, *message;
850 const char *str_c, *str_V, *str_h, *str_F, *str_r;
851 IF_FEATURE_UDHCP_PORT(char *str_P;)
852 llist_t *list_O = NULL;
853 llist_t *list_x = NULL;
854 int tryagain_timeout = 20;
855 int discover_timeout = 3;
856 int discover_retries = 3;
857 uint32_t server_addr = server_addr; /* for compiler */
858 uint32_t requested_ip = 0;
860 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
862 int timeout; /* must be signed */
863 unsigned already_waited_sec;
868 struct dhcp_packet packet;
872 static const char udhcpc_longopts[] ALIGN1 =
873 "clientid\0" Required_argument "c"
874 "clientid-none\0" No_argument "C"
875 "vendorclass\0" Required_argument "V"
876 "hostname\0" Required_argument "H"
877 "fqdn\0" Required_argument "F"
878 "interface\0" Required_argument "i"
879 "now\0" No_argument "n"
880 "pidfile\0" Required_argument "p"
881 "quit\0" No_argument "q"
882 "release\0" No_argument "R"
883 "request\0" Required_argument "r"
884 "script\0" Required_argument "s"
885 "timeout\0" Required_argument "T"
886 "version\0" No_argument "v"
887 "retries\0" Required_argument "t"
888 "tryagain\0" Required_argument "A"
889 "syslog\0" No_argument "S"
890 "request-option\0" Required_argument "O"
891 "no-default-options\0" No_argument "o"
892 "foreground\0" No_argument "f"
893 "background\0" No_argument "b"
894 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
895 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
920 /* The rest has variable bit positions, need to be clever */
922 USE_FOR_MMU( OPTBIT_b,)
923 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
924 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
925 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
926 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
927 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
930 /* Default options. */
931 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
932 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
933 client_config.interface = "eth0";
934 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
935 str_V = "udhcp "BB_VER;
937 /* Parse command line */
938 /* Cc: mutually exclusive; O,x: list; -T,-t,-A take numeric param */
939 opt_complementary = "c--C:C--c:O::x::T+:t+:A+"
940 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
944 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
945 opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:f"
947 IF_FEATURE_UDHCPC_ARPING("a")
948 IF_FEATURE_UDHCP_PORT("P:")
950 , &str_c, &str_V, &str_h, &str_h, &str_F
951 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
952 , &client_config.script /* s */
953 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
956 IF_FEATURE_UDHCP_PORT(, &str_P)
957 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
961 if (opt & (OPT_h|OPT_H))
962 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
964 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
965 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
966 /* Flag bits: 0000NEOS
967 * S: 1 = Client requests server to update A RR in DNS as well as PTR
968 * O: 1 = Server indicates to client that DNS has been updated regardless
969 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
970 * not "host.domain.com". Format 0 is obsolete.
971 * N: 1 = Client requests server to not update DNS (S must be 0 then)
972 * Two [0] bytes which follow are deprecated and must be 0.
974 client_config.fqdn[OPT_DATA + 0] = 0x1;
975 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
976 /*client_config.fqdn[OPT_DATA + 2] = 0; */
979 requested_ip = inet_addr(str_r);
980 #if ENABLE_FEATURE_UDHCP_PORT
982 CLIENT_PORT = xatou16(str_P);
983 SERVER_PORT = CLIENT_PORT - 1;
987 client_config.no_default_options = 1;
989 char *optstr = llist_pop(&list_O);
990 unsigned n = udhcp_option_idx(optstr);
991 n = dhcp_optflags[n].code;
992 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
995 char *optstr = llist_pop(&list_x);
996 char *colon = strchr(optstr, ':');
999 /* now it looks similar to udhcpd's config file line:
1000 * "optname optval", using the common routine: */
1001 udhcp_str2optset(optstr, &client_config.options);
1004 if (udhcp_read_interface(client_config.interface,
1005 &client_config.ifindex,
1007 client_config.client_mac)
1013 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
1014 } else if (!(opt & OPT_C)) {
1015 /* not set and not suppressed, set the default client ID */
1016 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1017 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1018 memcpy(client_config.clientid + OPT_DATA+1, client_config.client_mac, 6);
1020 if (str_V[0] != '\0')
1021 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1023 /* on NOMMU reexec (i.e., background) early */
1024 if (!(opt & OPT_f)) {
1025 bb_daemonize_or_rexec(0 /* flags */, argv);
1026 logmode = LOGMODE_NONE;
1030 openlog(applet_name, LOG_PID, LOG_DAEMON);
1031 logmode |= LOGMODE_SYSLOG;
1034 /* Make sure fd 0,1,2 are open */
1035 bb_sanitize_stdio();
1036 /* Equivalent of doing a fflush after every \n */
1038 /* Create pidfile */
1039 write_pidfile(client_config.pidfile);
1040 /* Goes to stdout (unless NOMMU) and possibly syslog */
1041 bb_info_msg("%s (v"BB_VER") started", applet_name);
1042 /* Set up the signal pipe */
1044 /* We want random_xid to be random... */
1045 srand(monotonic_us());
1047 state = INIT_SELECTING;
1048 udhcp_run_script(NULL, "deconfig");
1049 change_listen_mode(LISTEN_RAW);
1052 already_waited_sec = 0;
1054 /* Main event loop. select() waits on signal pipe and possibly
1056 * "continue" statements in code below jump to the top of the loop.
1059 /* silence "uninitialized!" warning */
1060 unsigned timestamp_before_wait = timestamp_before_wait;
1062 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1064 /* Was opening raw or udp socket here
1065 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1066 * but on fast network renew responses return faster
1067 * than we open sockets. Thus this code is moved
1068 * to change_listen_mode(). Thus we open listen socket
1069 * BEFORE we send renew request (see "case BOUND:"). */
1071 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1073 tv.tv_sec = timeout - already_waited_sec;
1076 /* If we already timed out, fall through with retval = 0, else... */
1077 if ((int)tv.tv_sec > 0) {
1078 timestamp_before_wait = (unsigned)monotonic_sec();
1079 log1("Waiting on select...");
1080 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1082 /* EINTR? A signal was caught, don't panic */
1083 if (errno == EINTR) {
1084 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1087 /* Else: an error occured, panic! */
1088 bb_perror_msg_and_die("select");
1092 /* If timeout dropped to zero, time to become active:
1093 * resend discover/renew/whatever
1096 /* We will restart the wait in any case */
1097 already_waited_sec = 0;
1100 case INIT_SELECTING:
1101 if (packet_num < discover_retries) {
1102 if (packet_num == 0)
1105 send_discover(xid, requested_ip);
1106 timeout = discover_timeout;
1111 udhcp_run_script(NULL, "leasefail");
1112 #if BB_MMU /* -b is not supported on NOMMU */
1113 if (opt & OPT_b) { /* background if no lease */
1114 bb_info_msg("No lease, forking to background");
1115 client_background();
1116 /* do not background again! */
1117 opt = ((opt & ~OPT_b) | OPT_f);
1120 if (opt & OPT_n) { /* abort if no lease */
1121 bb_info_msg("No lease, failing");
1125 /* wait before trying again */
1126 timeout = tryagain_timeout;
1130 if (packet_num < discover_retries) {
1131 /* send broadcast select packet */
1132 send_select(xid, server_addr, requested_ip);
1133 timeout = discover_timeout;
1137 /* Timed out, go back to init state.
1138 * "discover...select...discover..." loops
1139 * were seen in the wild. Treat them similarly
1140 * to "no response to discover" case */
1141 change_listen_mode(LISTEN_RAW);
1142 state = INIT_SELECTING;
1145 /* 1/2 lease passed, enter renewing state */
1147 change_listen_mode(LISTEN_KERNEL);
1148 log1("Entering renew state");
1149 /* fall right through */
1150 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1151 case_RENEW_REQUESTED:
1154 /* send an unicast renew request */
1155 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1156 * a new UDP socket for sending inside send_renew.
1157 * I hazard to guess existing listening socket
1158 * is somehow conflicting with it, but why is it
1159 * not deterministic then?! Strange.
1160 * Anyway, it does recover by eventually failing through
1161 * into INIT_SELECTING state.
1163 send_renew(xid, server_addr, requested_ip);
1167 /* Timed out, enter rebinding state */
1168 log1("Entering rebinding state");
1170 /* fall right through */
1172 /* Switch to bcast receive */
1173 change_listen_mode(LISTEN_RAW);
1174 /* Lease is *really* about to run out,
1175 * try to find DHCP server using broadcast */
1177 /* send a broadcast renew request */
1178 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1182 /* Timed out, enter init state */
1183 bb_info_msg("Lease lost, entering init state");
1184 udhcp_run_script(NULL, "deconfig");
1185 state = INIT_SELECTING;
1186 /*timeout = 0; - already is */
1189 /* case RELEASED: */
1191 /* yah, I know, *you* say it would never happen */
1193 continue; /* back to main loop */
1194 } /* if select timed out */
1196 /* select() didn't timeout, something happened */
1198 /* Is it a signal? */
1199 /* note: udhcp_sp_read checks FD_ISSET before reading */
1200 switch (udhcp_sp_read(&rfds)) {
1203 if (state == RENEW_REQUESTED)
1204 goto case_RENEW_REQUESTED;
1205 /* Start things over */
1207 /* Kill any timeouts, user wants this to hurry along */
1211 perform_release(requested_ip, server_addr);
1215 bb_info_msg("Received SIGTERM");
1216 if (opt & OPT_R) /* release on quit */
1217 perform_release(requested_ip, server_addr);
1221 /* Is it a packet? */
1222 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1228 /* A packet is ready, read it */
1229 if (listen_mode == LISTEN_KERNEL)
1230 len = udhcp_recv_kernel_packet(&packet, sockfd);
1232 len = udhcp_recv_raw_packet(&packet, sockfd);
1234 /* Error is severe, reopen socket */
1235 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1236 sleep(discover_timeout); /* 3 seconds by default */
1237 change_listen_mode(listen_mode); /* just close and reopen */
1239 /* If this packet will turn out to be unrelated/bogus,
1240 * we will go back and wait for next one.
1241 * Be sure timeout is properly decreased. */
1242 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1247 if (packet.xid != xid) {
1248 log1("xid %x (our is %x), ignoring packet",
1249 (unsigned)packet.xid, (unsigned)xid);
1253 /* Ignore packets that aren't for us */
1254 if (packet.hlen != 6
1255 || memcmp(packet.chaddr, client_config.client_mac, 6)
1257 //FIXME: need to also check that last 10 bytes are zero
1258 log1("chaddr does not match, ignoring packet"); // log2?
1262 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1263 if (message == NULL) {
1264 bb_error_msg("no message type option, ignoring packet");
1269 case INIT_SELECTING:
1270 /* Must be a DHCPOFFER to one of our xid's */
1271 if (*message == DHCPOFFER) {
1272 /* TODO: why we don't just fetch server's IP from IP header? */
1273 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1275 bb_error_msg("no server ID in message");
1277 /* still selecting - this server looks bad */
1279 /* it IS unaligned sometimes, don't "optimize" */
1280 move_from_unaligned32(server_addr, temp);
1282 requested_ip = packet.yiaddr;
1284 /* enter requesting state */
1288 already_waited_sec = 0;
1293 case RENEW_REQUESTED:
1295 if (*message == DHCPACK) {
1296 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1298 bb_error_msg("no lease time with ACK, using 1 hour lease");
1299 lease_seconds = 60 * 60;
1301 /* it IS unaligned sometimes, don't "optimize" */
1302 move_from_unaligned32(lease_seconds, temp);
1303 lease_seconds = ntohl(lease_seconds);
1304 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1305 if (lease_seconds < 10) /* and not too small */
1308 #if ENABLE_FEATURE_UDHCPC_ARPING
1310 /* RFC 2131 3.1 paragraph 5:
1311 * "The client receives the DHCPACK message with configuration
1312 * parameters. The client SHOULD perform a final check on the
1313 * parameters (e.g., ARP for allocated network address), and notes
1314 * the duration of the lease specified in the DHCPACK message. At this
1315 * point, the client is configured. If the client detects that the
1316 * address is already in use (e.g., through the use of ARP),
1317 * the client MUST send a DHCPDECLINE message to the server and restarts
1318 * the configuration process..." */
1319 if (!arpping(packet.yiaddr,
1322 client_config.client_mac,
1323 client_config.interface)
1325 bb_info_msg("Offered address is in use "
1326 "(got ARP reply), declining");
1327 send_decline(xid, server_addr, packet.yiaddr);
1329 if (state != REQUESTING)
1330 udhcp_run_script(NULL, "deconfig");
1331 change_listen_mode(LISTEN_RAW);
1332 state = INIT_SELECTING;
1334 timeout = tryagain_timeout;
1336 already_waited_sec = 0;
1337 continue; /* back to main loop */
1341 /* enter bound state */
1342 timeout = lease_seconds / 2;
1344 struct in_addr temp_addr;
1345 temp_addr.s_addr = packet.yiaddr;
1346 bb_info_msg("Lease of %s obtained, lease time %u",
1347 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1349 requested_ip = packet.yiaddr;
1350 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1353 change_listen_mode(LISTEN_NONE);
1354 if (opt & OPT_q) { /* quit after lease */
1355 if (opt & OPT_R) /* release on quit */
1356 perform_release(requested_ip, server_addr);
1359 /* future renew failures should not exit (JM) */
1361 #if BB_MMU /* NOMMU case backgrounded earlier */
1362 if (!(opt & OPT_f)) {
1363 client_background();
1364 /* do not background again! */
1365 opt = ((opt & ~OPT_b) | OPT_f);
1368 already_waited_sec = 0;
1369 continue; /* back to main loop */
1371 if (*message == DHCPNAK) {
1372 /* return to init state */
1373 bb_info_msg("Received DHCP NAK");
1374 udhcp_run_script(&packet, "nak");
1375 if (state != REQUESTING)
1376 udhcp_run_script(NULL, "deconfig");
1377 change_listen_mode(LISTEN_RAW);
1378 sleep(3); /* avoid excessive network traffic */
1379 state = INIT_SELECTING;
1383 already_waited_sec = 0;
1386 /* case BOUND: - ignore all packets */
1387 /* case RELEASED: - ignore all packets */
1389 /* back to main loop */
1390 } /* for (;;) - main loop ends */
1395 /*if (client_config.pidfile) - remove_pidfile has its own check */
1396 remove_pidfile(client_config.pidfile);