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;
240 for (i = 0; dhcp_optflags[i].code; i++) {
241 if (udhcp_get_option(packet, dhcp_optflags[i].code)) {
243 if (dhcp_optflags[i].code == DHCP_SUBNET)
244 num_options++; /* for mton */
247 if (packet->siaddr_nip)
249 temp = udhcp_get_option(packet, DHCP_OPTION_OVERLOAD);
252 if (!(over & FILE_FIELD) && packet->file[0])
254 if (!(over & SNAME_FIELD) && packet->sname[0])
258 curr = envp = xzalloc(sizeof(char *) * (num_options + 3));
259 *curr = xasprintf("interface=%s", client_config.interface);
265 *curr = xmalloc(sizeof("ip=255.255.255.255"));
266 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
269 opt_name = dhcp_option_strings;
272 temp = udhcp_get_option(packet, dhcp_optflags[i].code);
275 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
278 /* Fill in a subnet bits option for things like /24 */
279 if (dhcp_optflags[i].code == DHCP_SUBNET) {
281 move_from_unaligned32(subnet, temp);
282 *curr = xasprintf("mask=%d", mton(subnet));
286 opt_name += strlen(opt_name) + 1;
289 if (packet->siaddr_nip) {
290 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
291 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
294 if (!(over & FILE_FIELD) && packet->file[0]) {
295 /* watch out for invalid packets */
296 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
299 if (!(over & SNAME_FIELD) && packet->sname[0]) {
300 /* watch out for invalid packets */
301 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
307 /* Call a script with a par file and env vars */
308 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
313 if (client_config.script == NULL)
316 envp = fill_envp(packet);
319 log1("Executing %s %s", client_config.script, name);
320 argv[0] = (char*) client_config.script;
321 argv[1] = (char*) name;
323 spawn_and_wait(argv);
325 for (curr = envp; *curr; curr++) {
334 /*** Sending/receiving packets ***/
336 static ALWAYS_INLINE uint32_t random_xid(void)
341 /* Initialize the packet with the proper defaults */
342 static void init_packet(struct dhcp_packet *packet, char type)
344 udhcp_init_header(packet, type);
345 memcpy(packet->chaddr, client_config.client_mac, 6);
346 if (client_config.clientid)
347 udhcp_add_binary_option(packet, client_config.clientid);
348 if (client_config.hostname)
349 udhcp_add_binary_option(packet, client_config.hostname);
350 if (client_config.fqdn)
351 udhcp_add_binary_option(packet, client_config.fqdn);
352 if (type != DHCPDECLINE
353 && type != DHCPRELEASE
354 && client_config.vendorclass
356 udhcp_add_binary_option(packet, client_config.vendorclass);
360 static void add_client_options(struct dhcp_packet *packet)
362 /* Add a "param req" option with the list of options we'd like to have
363 * from stubborn DHCP servers. Pull the data from the struct in common.c.
364 * No bounds checking because it goes towards the head of the packet. */
366 int end = udhcp_end_option(packet->options);
369 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
370 if (( (dhcp_optflags[i].flags & OPTION_REQ)
371 && !client_config.no_default_options
373 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
375 packet->options[end + OPT_DATA + len] = c;
380 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
381 packet->options[end + OPT_LEN] = len;
382 packet->options[end + OPT_DATA + len] = DHCP_END;
385 /* Add -x options if any */
387 struct option_set *curr = client_config.options;
389 udhcp_add_binary_option(packet, curr->data);
392 // if (client_config.sname)
393 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
394 // if (client_config.boot_file)
395 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
400 * 4.4.4 Use of broadcast and unicast
402 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
403 * messages, unless the client knows the address of a DHCP server.
404 * The client unicasts DHCPRELEASE messages to the server. Because
405 * the client is declining the use of the IP address supplied by the server,
406 * the client broadcasts DHCPDECLINE messages.
408 * When the DHCP client knows the address of a DHCP server, in either
409 * INIT or REBOOTING state, the client may use that address
410 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
411 * The client may also use unicast to send DHCPINFORM messages
412 * to a known DHCP server. If the client receives no response to DHCP
413 * messages sent to the IP address of a known DHCP server, the DHCP
414 * client reverts to using the IP broadcast address.
417 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
419 return udhcp_send_raw_packet(packet,
420 /*src*/ INADDR_ANY, CLIENT_PORT,
421 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
422 client_config.ifindex);
425 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
426 static int send_discover(uint32_t xid, uint32_t requested)
428 struct dhcp_packet packet;
430 init_packet(&packet, DHCPDISCOVER);
433 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
434 /* Explicitly saying that we want RFC-compliant packets helps
435 * some buggy DHCP servers to NOT send bigger packets */
436 udhcp_add_simple_option(&packet, DHCP_MAX_SIZE, htons(576));
437 add_client_options(&packet);
439 bb_info_msg("Sending discover...");
440 return raw_bcast_from_client_config_ifindex(&packet);
443 /* Broadcast a DHCP request message */
444 /* RFC 2131 3.1 paragraph 3:
445 * "The client _broadcasts_ a DHCPREQUEST message..."
447 static int send_select(uint32_t xid, uint32_t server, uint32_t requested)
449 struct dhcp_packet packet;
452 init_packet(&packet, DHCPREQUEST);
454 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
455 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
456 add_client_options(&packet);
458 addr.s_addr = requested;
459 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
460 return raw_bcast_from_client_config_ifindex(&packet);
463 /* Unicast or broadcast a DHCP renew message */
464 static int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
466 struct dhcp_packet packet;
468 init_packet(&packet, DHCPREQUEST);
470 packet.ciaddr = ciaddr;
471 add_client_options(&packet);
473 bb_info_msg("Sending renew...");
475 return udhcp_send_kernel_packet(&packet,
477 server, SERVER_PORT);
478 return raw_bcast_from_client_config_ifindex(&packet);
481 #if ENABLE_FEATURE_UDHCPC_ARPING
482 /* Broadcast a DHCP decline message */
483 static int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
485 struct dhcp_packet packet;
487 init_packet(&packet, DHCPDECLINE);
489 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
490 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
492 bb_info_msg("Sending decline...");
493 return raw_bcast_from_client_config_ifindex(&packet);
497 /* Unicast a DHCP release message */
498 static int send_release(uint32_t server, uint32_t ciaddr)
500 struct dhcp_packet packet;
502 init_packet(&packet, DHCPRELEASE);
503 packet.xid = random_xid();
504 packet.ciaddr = ciaddr;
506 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
508 bb_info_msg("Sending release...");
509 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
512 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
513 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
516 struct ip_udp_dhcp_packet packet;
519 memset(&packet, 0, sizeof(packet));
520 bytes = safe_read(fd, &packet, sizeof(packet));
522 log1("Packet read error, ignoring");
523 /* NB: possible down interface, etc. Caller should pause. */
524 return bytes; /* returns -1 */
527 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
528 log1("Packet is too short, ignoring");
532 if (bytes < ntohs(packet.ip.tot_len)) {
533 /* packet is bigger than sizeof(packet), we did partial read */
534 log1("Oversized packet, ignoring");
538 /* ignore any extra garbage bytes */
539 bytes = ntohs(packet.ip.tot_len);
541 /* make sure its the right packet for us, and that it passes sanity checks */
542 if (packet.ip.protocol != IPPROTO_UDP || packet.ip.version != IPVERSION
543 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
544 || packet.udp.dest != htons(CLIENT_PORT)
545 /* || bytes > (int) sizeof(packet) - can't happen */
546 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
548 log1("Unrelated/bogus packet, ignoring");
552 /* verify IP checksum */
553 check = packet.ip.check;
555 if (check != udhcp_checksum(&packet.ip, sizeof(packet.ip))) {
556 log1("Bad IP header checksum, ignoring");
560 /* verify UDP checksum. IP header has to be modified for this */
561 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
562 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
563 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
564 check = packet.udp.check;
565 packet.udp.check = 0;
566 if (check && check != udhcp_checksum(&packet, bytes)) {
567 log1("Packet with bad UDP checksum received, ignoring");
571 memcpy(dhcp_pkt, &packet.data, bytes - (sizeof(packet.ip) + sizeof(packet.udp)));
573 if (dhcp_pkt->cookie != htonl(DHCP_MAGIC)) {
574 bb_info_msg("Packet with bad magic, ignoring");
577 log1("Got valid DHCP packet");
578 udhcp_dump_packet(dhcp_pkt);
579 return bytes - (sizeof(packet.ip) + sizeof(packet.udp));
585 static int sockfd = -1;
587 #define LISTEN_NONE 0
588 #define LISTEN_KERNEL 1
590 static smallint listen_mode;
592 /* initial state: (re)start DHCP negotiation */
593 #define INIT_SELECTING 0
594 /* discover was sent, DHCPOFFER reply received */
596 /* select/renew was sent, DHCPACK reply received */
598 /* half of lease passed, want to renew it by sending unicast renew requests */
600 /* renew requests were not answered, lease is almost over, send broadcast renew */
602 /* manually requested renew (SIGUSR1) */
603 #define RENEW_REQUESTED 5
604 /* release, possibly manually requested (SIGUSR2) */
606 static smallint state;
608 static int udhcp_raw_socket(int ifindex)
611 struct sockaddr_ll sock;
616 * I've selected not to see LL header, so BPF doesn't see it, too.
617 * The filter may also pass non-IP and non-ARP packets, but we do
618 * a more complete check when receiving the message in userspace.
620 * and filter shamelessly stolen from:
622 * http://www.flamewarmaster.de/software/dhcpclient/
624 * There are a few other interesting ideas on that page (look under
625 * "Motivation"). Use of netlink events is most interesting. Think
626 * of various network servers listening for events and reconfiguring.
627 * That would obsolete sending HUP signals and/or make use of restarts.
629 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
632 * TODO: make conditional?
634 #define SERVER_AND_CLIENT_PORTS ((67 << 16) + 68)
635 static const struct sock_filter filter_instr[] = {
637 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
638 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 2, 0), /* L5, L1, is UDP? */
639 /* ugly check for arp on ethernet-like and IPv4 */
640 BPF_STMT(BPF_LD|BPF_W|BPF_ABS, 2), /* L1: */
641 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 0x08000604, 3, 4), /* L3, L4 */
643 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0), /* L5: */
644 /* check udp source and destination ports */
645 BPF_STMT(BPF_LD|BPF_W|BPF_IND, 0),
646 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, SERVER_AND_CLIENT_PORTS, 0, 1), /* L3, L4 */
648 BPF_STMT(BPF_RET|BPF_K, 0x0fffffff ), /* L3: pass */
649 BPF_STMT(BPF_RET|BPF_K, 0), /* L4: reject */
651 static const struct sock_fprog filter_prog = {
652 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
653 /* casting const away: */
654 .filter = (struct sock_filter *) filter_instr,
657 log1("Opening raw socket on ifindex %d", ifindex); //log2?
659 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
660 log1("Got raw socket fd %d", fd); //log2?
662 if (SERVER_PORT == 67 && CLIENT_PORT == 68) {
663 /* Use only if standard ports are in use */
664 /* Ignoring error (kernel may lack support for this) */
665 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
666 sizeof(filter_prog)) >= 0)
667 log1("Attached filter to raw socket fd %d", fd); // log?
670 sock.sll_family = AF_PACKET;
671 sock.sll_protocol = htons(ETH_P_IP);
672 sock.sll_ifindex = ifindex;
673 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
674 log1("Created raw socket");
679 static void change_listen_mode(int new_mode)
681 log1("Entering listen mode: %s",
682 new_mode != LISTEN_NONE
683 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
687 listen_mode = new_mode;
692 if (new_mode == LISTEN_KERNEL)
693 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
694 else if (new_mode != LISTEN_NONE)
695 sockfd = udhcp_raw_socket(client_config.ifindex);
696 /* else LISTEN_NONE: sockfd stays closed */
699 static void perform_renew(void)
701 bb_info_msg("Performing a DHCP renew");
704 change_listen_mode(LISTEN_KERNEL);
707 state = RENEW_REQUESTED;
709 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
710 udhcp_run_script(NULL, "deconfig");
713 change_listen_mode(LISTEN_RAW);
714 state = INIT_SELECTING;
721 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
723 char buffer[sizeof("255.255.255.255")];
724 struct in_addr temp_addr;
726 /* send release packet */
727 if (state == BOUND || state == RENEWING || state == REBINDING) {
728 temp_addr.s_addr = server_addr;
729 strcpy(buffer, inet_ntoa(temp_addr));
730 temp_addr.s_addr = requested_ip;
731 bb_info_msg("Unicasting a release of %s to %s",
732 inet_ntoa(temp_addr), buffer);
733 send_release(server_addr, requested_ip); /* unicast */
734 udhcp_run_script(NULL, "deconfig");
736 bb_info_msg("Entering released state");
738 change_listen_mode(LISTEN_NONE);
742 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
745 int len = strnlen(str, 255);
746 storage = xzalloc(len + extra + OPT_DATA);
747 storage[OPT_CODE] = code;
748 storage[OPT_LEN] = len + extra;
749 memcpy(storage + extra + OPT_DATA, str, len);
754 static void client_background(void)
757 logmode &= ~LOGMODE_STDIO;
758 /* rewrite pidfile, as our pid is different now */
759 write_pidfile(client_config.pidfile);
763 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
764 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
766 uint8_t *temp, *message;
767 const char *str_c, *str_V, *str_h, *str_F, *str_r;
768 IF_FEATURE_UDHCP_PORT(char *str_P;)
769 llist_t *list_O = NULL;
770 llist_t *list_x = NULL;
771 int tryagain_timeout = 20;
772 int discover_timeout = 3;
773 int discover_retries = 3;
774 uint32_t server_addr = server_addr; /* for compiler */
775 uint32_t requested_ip = 0;
777 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
779 int timeout; /* must be signed */
780 unsigned already_waited_sec;
785 struct dhcp_packet packet;
789 static const char udhcpc_longopts[] ALIGN1 =
790 "clientid\0" Required_argument "c"
791 "clientid-none\0" No_argument "C"
792 "vendorclass\0" Required_argument "V"
793 "hostname\0" Required_argument "H"
794 "fqdn\0" Required_argument "F"
795 "interface\0" Required_argument "i"
796 "now\0" No_argument "n"
797 "pidfile\0" Required_argument "p"
798 "quit\0" No_argument "q"
799 "release\0" No_argument "R"
800 "request\0" Required_argument "r"
801 "script\0" Required_argument "s"
802 "timeout\0" Required_argument "T"
803 "version\0" No_argument "v"
804 "retries\0" Required_argument "t"
805 "tryagain\0" Required_argument "A"
806 "syslog\0" No_argument "S"
807 "request-option\0" Required_argument "O"
808 "no-default-options\0" No_argument "o"
809 "foreground\0" No_argument "f"
810 "background\0" No_argument "b"
811 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
812 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
837 /* The rest has variable bit positions, need to be clever */
839 USE_FOR_MMU( OPTBIT_b,)
840 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
841 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
842 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
843 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
844 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
847 /* Default options. */
848 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
849 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
850 client_config.interface = "eth0";
851 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
852 str_V = "udhcp "BB_VER;
854 /* Parse command line */
855 /* Cc: mutually exclusive; O,x: list; -T,-t,-A take numeric param */
856 opt_complementary = "c--C:C--c:O::x::T+:t+:A+"
857 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
861 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
862 opt = getopt32(argv, "c:CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:f"
864 IF_FEATURE_UDHCPC_ARPING("a")
865 IF_FEATURE_UDHCP_PORT("P:")
867 , &str_c, &str_V, &str_h, &str_h, &str_F
868 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
869 , &client_config.script /* s */
870 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
873 IF_FEATURE_UDHCP_PORT(, &str_P)
874 #if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
878 if (opt & (OPT_h|OPT_H))
879 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
881 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
882 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
883 /* Flag bits: 0000NEOS
884 * S: 1 = Client requests server to update A RR in DNS as well as PTR
885 * O: 1 = Server indicates to client that DNS has been updated regardless
886 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
887 * not "host.domain.com". Format 0 is obsolete.
888 * N: 1 = Client requests server to not update DNS (S must be 0 then)
889 * Two [0] bytes which follow are deprecated and must be 0.
891 client_config.fqdn[OPT_DATA + 0] = 0x1;
892 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
893 /*client_config.fqdn[OPT_DATA + 2] = 0; */
896 requested_ip = inet_addr(str_r);
897 #if ENABLE_FEATURE_UDHCP_PORT
899 CLIENT_PORT = xatou16(str_P);
900 SERVER_PORT = CLIENT_PORT - 1;
904 client_config.no_default_options = 1;
906 char *optstr = llist_pop(&list_O);
907 unsigned n = udhcp_option_idx(optstr);
908 n = dhcp_optflags[n].code;
909 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
912 char *optstr = llist_pop(&list_x);
913 char *colon = strchr(optstr, ':');
916 /* now it looks similar to udhcpd's config file line:
917 * "optname optval", using the common routine: */
918 udhcp_str2optset(optstr, &client_config.options);
921 if (udhcp_read_interface(client_config.interface,
922 &client_config.ifindex,
924 client_config.client_mac)
930 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, str_c, 0);
931 } else if (!(opt & OPT_C)) {
932 /* not set and not suppressed, set the default client ID */
933 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
934 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
935 memcpy(client_config.clientid + OPT_DATA+1, client_config.client_mac, 6);
937 if (str_V[0] != '\0')
938 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
940 /* on NOMMU reexec (i.e., background) early */
941 if (!(opt & OPT_f)) {
942 bb_daemonize_or_rexec(0 /* flags */, argv);
943 logmode = LOGMODE_NONE;
947 openlog(applet_name, LOG_PID, LOG_DAEMON);
948 logmode |= LOGMODE_SYSLOG;
951 /* Make sure fd 0,1,2 are open */
953 /* Equivalent of doing a fflush after every \n */
956 write_pidfile(client_config.pidfile);
957 /* Goes to stdout (unless NOMMU) and possibly syslog */
958 bb_info_msg("%s (v"BB_VER") started", applet_name);
959 /* Set up the signal pipe */
961 /* We want random_xid to be random... */
962 srand(monotonic_us());
964 state = INIT_SELECTING;
965 udhcp_run_script(NULL, "deconfig");
966 change_listen_mode(LISTEN_RAW);
969 already_waited_sec = 0;
971 /* Main event loop. select() waits on signal pipe and possibly
973 * "continue" statements in code below jump to the top of the loop.
976 /* silence "uninitialized!" warning */
977 unsigned timestamp_before_wait = timestamp_before_wait;
979 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
981 /* Was opening raw or udp socket here
982 * if (listen_mode != LISTEN_NONE && sockfd < 0),
983 * but on fast network renew responses return faster
984 * than we open sockets. Thus this code is moved
985 * to change_listen_mode(). Thus we open listen socket
986 * BEFORE we send renew request (see "case BOUND:"). */
988 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
990 tv.tv_sec = timeout - already_waited_sec;
993 /* If we already timed out, fall through with retval = 0, else... */
994 if ((int)tv.tv_sec > 0) {
995 timestamp_before_wait = (unsigned)monotonic_sec();
996 log1("Waiting on select...");
997 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
999 /* EINTR? A signal was caught, don't panic */
1000 if (errno == EINTR) {
1001 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1004 /* Else: an error occured, panic! */
1005 bb_perror_msg_and_die("select");
1009 /* If timeout dropped to zero, time to become active:
1010 * resend discover/renew/whatever
1013 /* We will restart the wait in any case */
1014 already_waited_sec = 0;
1017 case INIT_SELECTING:
1018 if (packet_num < discover_retries) {
1019 if (packet_num == 0)
1022 send_discover(xid, requested_ip);
1023 timeout = discover_timeout;
1028 udhcp_run_script(NULL, "leasefail");
1029 #if BB_MMU /* -b is not supported on NOMMU */
1030 if (opt & OPT_b) { /* background if no lease */
1031 bb_info_msg("No lease, forking to background");
1032 client_background();
1033 /* do not background again! */
1034 opt = ((opt & ~OPT_b) | OPT_f);
1037 if (opt & OPT_n) { /* abort if no lease */
1038 bb_info_msg("No lease, failing");
1042 /* wait before trying again */
1043 timeout = tryagain_timeout;
1047 if (packet_num < discover_retries) {
1048 /* send broadcast select packet */
1049 send_select(xid, server_addr, requested_ip);
1050 timeout = discover_timeout;
1054 /* Timed out, go back to init state.
1055 * "discover...select...discover..." loops
1056 * were seen in the wild. Treat them similarly
1057 * to "no response to discover" case */
1058 change_listen_mode(LISTEN_RAW);
1059 state = INIT_SELECTING;
1062 /* 1/2 lease passed, enter renewing state */
1064 change_listen_mode(LISTEN_KERNEL);
1065 log1("Entering renew state");
1066 /* fall right through */
1067 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1068 case_RENEW_REQUESTED:
1071 /* send an unicast renew request */
1072 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1073 * a new UDP socket for sending inside send_renew.
1074 * I hazard to guess existing listening socket
1075 * is somehow conflicting with it, but why is it
1076 * not deterministic then?! Strange.
1077 * Anyway, it does recover by eventually failing through
1078 * into INIT_SELECTING state.
1080 send_renew(xid, server_addr, requested_ip);
1084 /* Timed out, enter rebinding state */
1085 log1("Entering rebinding state");
1087 /* fall right through */
1089 /* Switch to bcast receive */
1090 change_listen_mode(LISTEN_RAW);
1091 /* Lease is *really* about to run out,
1092 * try to find DHCP server using broadcast */
1094 /* send a broadcast renew request */
1095 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1099 /* Timed out, enter init state */
1100 bb_info_msg("Lease lost, entering init state");
1101 udhcp_run_script(NULL, "deconfig");
1102 state = INIT_SELECTING;
1103 /*timeout = 0; - already is */
1106 /* case RELEASED: */
1108 /* yah, I know, *you* say it would never happen */
1110 continue; /* back to main loop */
1111 } /* if select timed out */
1113 /* select() didn't timeout, something happened */
1115 /* Is it a signal? */
1116 /* note: udhcp_sp_read checks FD_ISSET before reading */
1117 switch (udhcp_sp_read(&rfds)) {
1120 if (state == RENEW_REQUESTED)
1121 goto case_RENEW_REQUESTED;
1122 /* Start things over */
1124 /* Kill any timeouts, user wants this to hurry along */
1128 perform_release(requested_ip, server_addr);
1132 bb_info_msg("Received SIGTERM");
1133 if (opt & OPT_R) /* release on quit */
1134 perform_release(requested_ip, server_addr);
1138 /* Is it a packet? */
1139 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1145 /* A packet is ready, read it */
1146 if (listen_mode == LISTEN_KERNEL)
1147 len = udhcp_recv_kernel_packet(&packet, sockfd);
1149 len = udhcp_recv_raw_packet(&packet, sockfd);
1151 /* Error is severe, reopen socket */
1152 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1153 sleep(discover_timeout); /* 3 seconds by default */
1154 change_listen_mode(listen_mode); /* just close and reopen */
1156 /* If this packet will turn out to be unrelated/bogus,
1157 * we will go back and wait for next one.
1158 * Be sure timeout is properly decreased. */
1159 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1164 if (packet.xid != xid) {
1165 log1("xid %x (our is %x), ignoring packet",
1166 (unsigned)packet.xid, (unsigned)xid);
1170 /* Ignore packets that aren't for us */
1171 if (packet.hlen != 6
1172 || memcmp(packet.chaddr, client_config.client_mac, 6)
1174 //FIXME: need to also check that last 10 bytes are zero
1175 log1("chaddr does not match, ignoring packet"); // log2?
1179 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1180 if (message == NULL) {
1181 bb_error_msg("no message type option, ignoring packet");
1186 case INIT_SELECTING:
1187 /* Must be a DHCPOFFER to one of our xid's */
1188 if (*message == DHCPOFFER) {
1189 /* TODO: why we don't just fetch server's IP from IP header? */
1190 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1192 bb_error_msg("no server ID in message");
1194 /* still selecting - this server looks bad */
1196 /* it IS unaligned sometimes, don't "optimize" */
1197 move_from_unaligned32(server_addr, temp);
1199 requested_ip = packet.yiaddr;
1201 /* enter requesting state */
1205 already_waited_sec = 0;
1210 case RENEW_REQUESTED:
1212 if (*message == DHCPACK) {
1213 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1215 bb_error_msg("no lease time with ACK, using 1 hour lease");
1216 lease_seconds = 60 * 60;
1218 /* it IS unaligned sometimes, don't "optimize" */
1219 move_from_unaligned32(lease_seconds, temp);
1220 lease_seconds = ntohl(lease_seconds);
1221 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1222 if (lease_seconds < 10) /* and not too small */
1225 #if ENABLE_FEATURE_UDHCPC_ARPING
1227 /* RFC 2131 3.1 paragraph 5:
1228 * "The client receives the DHCPACK message with configuration
1229 * parameters. The client SHOULD perform a final check on the
1230 * parameters (e.g., ARP for allocated network address), and notes
1231 * the duration of the lease specified in the DHCPACK message. At this
1232 * point, the client is configured. If the client detects that the
1233 * address is already in use (e.g., through the use of ARP),
1234 * the client MUST send a DHCPDECLINE message to the server and restarts
1235 * the configuration process..." */
1236 if (!arpping(packet.yiaddr,
1239 client_config.client_mac,
1240 client_config.interface)
1242 bb_info_msg("Offered address is in use "
1243 "(got ARP reply), declining");
1244 send_decline(xid, server_addr, packet.yiaddr);
1246 if (state != REQUESTING)
1247 udhcp_run_script(NULL, "deconfig");
1248 change_listen_mode(LISTEN_RAW);
1249 state = INIT_SELECTING;
1251 timeout = tryagain_timeout;
1253 already_waited_sec = 0;
1254 continue; /* back to main loop */
1258 /* enter bound state */
1259 timeout = lease_seconds / 2;
1261 struct in_addr temp_addr;
1262 temp_addr.s_addr = packet.yiaddr;
1263 bb_info_msg("Lease of %s obtained, lease time %u",
1264 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1266 requested_ip = packet.yiaddr;
1267 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1270 change_listen_mode(LISTEN_NONE);
1271 if (opt & OPT_q) { /* quit after lease */
1272 if (opt & OPT_R) /* release on quit */
1273 perform_release(requested_ip, server_addr);
1276 /* future renew failures should not exit (JM) */
1278 #if BB_MMU /* NOMMU case backgrounded earlier */
1279 if (!(opt & OPT_f)) {
1280 client_background();
1281 /* do not background again! */
1282 opt = ((opt & ~OPT_b) | OPT_f);
1285 already_waited_sec = 0;
1286 continue; /* back to main loop */
1288 if (*message == DHCPNAK) {
1289 /* return to init state */
1290 bb_info_msg("Received DHCP NAK");
1291 udhcp_run_script(&packet, "nak");
1292 if (state != REQUESTING)
1293 udhcp_run_script(NULL, "deconfig");
1294 change_listen_mode(LISTEN_RAW);
1295 sleep(3); /* avoid excessive network traffic */
1296 state = INIT_SELECTING;
1300 already_waited_sec = 0;
1303 /* case BOUND: - ignore all packets */
1304 /* case RELEASED: - ignore all packets */
1306 /* back to main loop */
1307 } /* for (;;) - main loop ends */
1312 /*if (client_config.pidfile) - remove_pidfile has its own check */
1313 remove_pidfile(client_config.pidfile);