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 <netinet/if_ether.h>
29 #include <linux/filter.h>
30 #include <linux/if_packet.h>
32 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
36 static const char udhcpc_longopts[] ALIGN1 =
37 "clientid-none\0" No_argument "C"
38 "vendorclass\0" Required_argument "V"
39 "hostname\0" Required_argument "H"
40 "fqdn\0" Required_argument "F"
41 "interface\0" Required_argument "i"
42 "now\0" No_argument "n"
43 "pidfile\0" Required_argument "p"
44 "quit\0" No_argument "q"
45 "release\0" No_argument "R"
46 "request\0" Required_argument "r"
47 "script\0" Required_argument "s"
48 "timeout\0" Required_argument "T"
49 "retries\0" Required_argument "t"
50 "tryagain\0" Required_argument "A"
51 "syslog\0" No_argument "S"
52 "request-option\0" Required_argument "O"
53 "no-default-options\0" No_argument "o"
54 "foreground\0" No_argument "f"
55 "background\0" No_argument "b"
56 "broadcast\0" No_argument "B"
57 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
58 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
61 /* Must match getopt32 option string order */
84 /* The rest has variable bit positions, need to be clever */
86 USE_FOR_MMU( OPTBIT_b,)
87 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
88 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
89 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
90 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
91 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
95 /*** Script execution code ***/
97 /* get a rough idea of how long an option will be (rounding up...) */
98 static const uint8_t len_of_option_as_string[] = {
99 [OPTION_IP ] = sizeof("255.255.255.255 "),
100 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
101 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
102 [OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
103 [OPTION_STRING ] = 1,
104 [OPTION_STRING_HOST ] = 1,
105 #if ENABLE_FEATURE_UDHCP_RFC3397
106 [OPTION_DNS_STRING ] = 1, /* unused */
107 /* Hmmm, this severely overestimates size if SIP_SERVERS option
108 * is in domain name form: N-byte option in binary form
109 * mallocs ~16*N bytes. But it is freed almost at once.
111 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
113 // [OPTION_BOOLEAN ] = sizeof("yes "),
114 [OPTION_U8 ] = sizeof("255 "),
115 [OPTION_U16 ] = sizeof("65535 "),
116 // [OPTION_S16 ] = sizeof("-32768 "),
117 [OPTION_U32 ] = sizeof("4294967295 "),
118 [OPTION_S32 ] = sizeof("-2147483684 "),
121 /* note: ip is a pointer to an IP in network order, possibly misaliged */
122 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
124 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
127 /* really simple implementation, just count the bits */
128 static int mton(uint32_t mask)
131 mask = ntohl(mask); /* 111110000-like bit pattern */
139 /* Check if a given label represents a valid DNS label
140 * Return pointer to the first character after the label upon success,
144 /* We don't need to be particularly anal. For example, allowing _, hyphen
145 * at the end, or leading and trailing dots would be ok, since it
146 * can't be used for attacks. (Leading hyphen can be, if someone uses
148 * in the script: then hostname may be treated as an option)
150 static const char *valid_domain_label(const char *label)
157 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
159 /* label must begin with letter */
162 if (ch < '0' || ch > '9') {
163 if (ch == '\0' || ch == '.')
165 /* DNS allows only '-', but we are more permissive */
166 if (ch != '-' && ch != '_')
173 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
178 /* Check if a given name represents a valid DNS name */
179 /* See RFC1035, 2.3.1 */
180 static int good_hostname(const char *name)
182 //const char *start = name;
185 name = valid_domain_label(name);
191 //return ((name - start) < 1025); /* NS_MAXDNAME */
196 /* Create "opt_name=opt_value" string */
197 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
199 unsigned upper_length;
200 int len, type, optlen;
203 /* option points to OPT_DATA, need to go back to get OPT_LEN */
204 len = option[-OPT_DATA + OPT_LEN];
206 type = optflag->flags & OPTION_TYPE_MASK;
207 optlen = dhcp_option_lengths[type];
208 upper_length = len_of_option_as_string[type]
209 * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
211 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
212 dest += sprintf(ret, "%s=", opt_name);
214 while (len >= optlen) {
218 dest += sprint_nip(dest, "", option);
219 if (type == OPTION_IP)
221 dest += sprint_nip(dest, "/", option + 4);
223 // case OPTION_BOOLEAN:
224 // dest += sprintf(dest, *option ? "yes" : "no");
227 dest += sprintf(dest, "%u", *option);
232 move_from_unaligned16(val_u16, option);
233 dest += sprintf(dest, "%u", ntohs(val_u16));
239 move_from_unaligned32(val_u32, option);
240 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
243 /* Note: options which use 'return' instead of 'break'
244 * (for example, OPTION_STRING) skip the code which handles
245 * the case of list of options.
248 case OPTION_STRING_HOST:
249 memcpy(dest, option, len);
251 if (type == OPTION_STRING_HOST && !good_hostname(dest))
252 safe_strncpy(dest, "bad", len);
254 case OPTION_STATIC_ROUTES: {
255 /* Option binary format:
256 * mask [one byte, 0..32]
257 * ip [big endian, 0..4 bytes depending on mask]
258 * router [big endian, 4 bytes]
261 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
263 const char *pfx = "";
265 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
278 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
279 while (--bytes >= 0) {
287 dest += sprint_nip(dest, pfx, (void*) &nip);
289 dest += sprintf(dest, "/%u ", mask);
291 dest += sprint_nip(dest, "", option);
299 /* Option binary format (see RFC 5969):
301 * 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
302 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
303 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
304 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
306 * ... (16 octets) ...
307 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
308 * ... 6rdBRIPv4Address(es) ...
309 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
310 * We convert it to a string
311 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
313 * Sanity check: ensure that our length is at least 22 bytes, that
315 * 6rdPrefixLen <= 128,
316 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
317 * (2nd condition need no check - it follows from 1st and 3rd).
318 * Else, return envvar with empty value ("optname=")
320 if (len >= (1 + 1 + 16 + 4)
322 && (option[1] + 32 - option[0]) <= 128
325 dest += sprintf(dest, "%u ", *option++);
327 dest += sprintf(dest, "%u ", *option++);
329 dest += sprint_nip6(dest, /* "", */ option);
331 len -= 1 + 1 + 16 + 4;
332 /* "+ 4" above corresponds to the length of IPv4 addr
333 * we consume in the loop below */
335 /* 6rdBRIPv4Address(es) */
336 dest += sprint_nip(dest, " ", option);
338 len -= 4; /* do we have yet another 4+ bytes? */
345 #if ENABLE_FEATURE_UDHCP_RFC3397
346 case OPTION_DNS_STRING:
347 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
348 dest = dname_dec(option, len, ret);
353 /* error. return "optname=" string */
355 case OPTION_SIP_SERVERS:
356 /* Option binary format:
358 * type=0: domain names, dns-compressed
363 if (option[-1] == 0) {
364 dest = dname_dec(option, len, ret);
370 if (option[-1] == 1) {
371 const char *pfx = "";
376 dest += sprint_nip(dest, pfx, option);
385 /* If we are here, try to format any remaining data
386 * in the option as another, similarly-formatted option
390 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
391 // Should we bail out/warn if we see multi-ip option which is
392 // not allowed to be such (for example, DHCP_BROADCAST)? -
393 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
402 /* put all the parameters into the environment */
403 static char **fill_envp(struct dhcp_packet *packet)
408 const char *opt_name;
410 uint8_t overload = 0;
412 #define BITMAP unsigned
413 #define BBITS (sizeof(BITMAP) * 8)
414 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
415 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
416 BITMAP found_opts[256 / BBITS];
418 memset(found_opts, 0, sizeof(found_opts));
420 /* We need 6 elements for:
422 * "ip=N.N.N.N" from packet->yiaddr
423 * "siaddr=IP" from packet->siaddr_nip (unless 0)
424 * "boot_file=FILE" from packet->file (unless overloaded)
425 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
429 /* +1 element for each option, +2 for subnet option: */
431 /* note: do not search for "pad" (0) and "end" (255) options */
432 //TODO: change logic to scan packet _once_
433 for (i = 1; i < 255; i++) {
434 temp = udhcp_get_option(packet, i);
436 if (i == DHCP_OPTION_OVERLOAD)
438 else if (i == DHCP_SUBNET)
439 envc++; /* for $mask */
441 /*if (i != DHCP_MESSAGE_TYPE)*/
442 FOUND_OPTS(i) |= BMASK(i);
446 curr = envp = xzalloc(sizeof(envp[0]) * envc);
448 *curr = xasprintf("interface=%s", client_config.interface);
454 /* Export BOOTP fields. Fields we don't (yet?) export:
455 * uint8_t op; // always BOOTREPLY
456 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
457 * uint8_t hlen; // hardware address length
458 * uint8_t hops; // used by relay agents only
460 * uint16_t secs; // elapsed since client began acquisition/renewal
461 * uint16_t flags; // only one flag so far: bcast. Never set by server
462 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
463 * // if during renew server wants to give us differn IP?)
464 * uint32_t gateway_nip; // relay agent IP address
465 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
466 * TODO: export gateway_nip as $giaddr?
468 /* Most important one: yiaddr as $ip */
469 *curr = xmalloc(sizeof("ip=255.255.255.255"));
470 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
472 if (packet->siaddr_nip) {
473 /* IP address of next server to use in bootstrap */
474 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
475 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
478 if (!(overload & FILE_FIELD) && packet->file[0]) {
479 /* watch out for invalid packets */
480 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
483 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
484 /* watch out for invalid packets */
485 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
489 /* Export known DHCP options */
490 opt_name = dhcp_option_strings;
493 uint8_t code = dhcp_optflags[i].code;
494 BITMAP *found_ptr = &FOUND_OPTS(code);
495 BITMAP found_mask = BMASK(code);
496 if (!(*found_ptr & found_mask))
498 *found_ptr &= ~found_mask; /* leave only unknown options */
499 temp = udhcp_get_option(packet, code);
500 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
502 if (code == DHCP_SUBNET) {
503 /* Subnet option: make things like "$ip/$mask" possible */
505 move_from_unaligned32(subnet, temp);
506 *curr = xasprintf("mask=%u", mton(subnet));
510 opt_name += strlen(opt_name) + 1;
513 /* Export unknown options */
514 for (i = 0; i < 256;) {
515 BITMAP bitmap = FOUND_OPTS(i);
520 if (bitmap & BMASK(i)) {
523 temp = udhcp_get_option(packet, i);
524 /* udhcp_get_option returns ptr to data portion,
525 * need to go back to get len
527 len = temp[-OPT_DATA + OPT_LEN];
528 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
529 ofs = sprintf(*curr, "opt%u=", i);
530 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
539 /* Call a script with a par file and env vars */
540 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
545 envp = fill_envp(packet);
548 log1("Executing %s %s", client_config.script, name);
549 argv[0] = (char*) client_config.script;
550 argv[1] = (char*) name;
552 spawn_and_wait(argv);
554 for (curr = envp; *curr; curr++) {
556 bb_unsetenv_and_free(*curr);
562 /*** Sending/receiving packets ***/
564 static ALWAYS_INLINE uint32_t random_xid(void)
569 /* Initialize the packet with the proper defaults */
570 static void init_packet(struct dhcp_packet *packet, char type)
574 /* Fill in: op, htype, hlen, cookie fields; message type option: */
575 udhcp_init_header(packet, type);
577 packet->xid = random_xid();
579 client_config.last_secs = monotonic_sec();
580 if (client_config.first_secs == 0)
581 client_config.first_secs = client_config.last_secs;
582 secs = client_config.last_secs - client_config.first_secs;
583 packet->secs = htons(secs);
585 memcpy(packet->chaddr, client_config.client_mac, 6);
586 if (client_config.clientid)
587 udhcp_add_binary_option(packet, client_config.clientid);
590 static void add_client_options(struct dhcp_packet *packet)
594 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
596 /* Add a "param req" option with the list of options we'd like to have
597 * from stubborn DHCP servers. Pull the data from the struct in common.c.
598 * No bounds checking because it goes towards the head of the packet. */
599 end = udhcp_end_option(packet->options);
601 for (i = 1; i < DHCP_END; i++) {
602 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
603 packet->options[end + OPT_DATA + len] = i;
608 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
609 packet->options[end + OPT_LEN] = len;
610 packet->options[end + OPT_DATA + len] = DHCP_END;
613 if (client_config.vendorclass)
614 udhcp_add_binary_option(packet, client_config.vendorclass);
615 if (client_config.hostname)
616 udhcp_add_binary_option(packet, client_config.hostname);
617 if (client_config.fqdn)
618 udhcp_add_binary_option(packet, client_config.fqdn);
620 /* Request broadcast replies if we have no IP addr */
621 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
622 packet->flags |= htons(BROADCAST_FLAG);
624 /* Add -x options if any */
626 struct option_set *curr = client_config.options;
628 udhcp_add_binary_option(packet, curr->data);
631 // if (client_config.sname)
632 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
633 // if (client_config.boot_file)
634 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
637 // This will be needed if we remove -V VENDOR_STR in favor of
638 // -x vendor:VENDOR_STR
639 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
640 // /* not set, set the default vendor ID */
641 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
645 * 4.4.4 Use of broadcast and unicast
647 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
648 * messages, unless the client knows the address of a DHCP server.
649 * The client unicasts DHCPRELEASE messages to the server. Because
650 * the client is declining the use of the IP address supplied by the server,
651 * the client broadcasts DHCPDECLINE messages.
653 * When the DHCP client knows the address of a DHCP server, in either
654 * INIT or REBOOTING state, the client may use that address
655 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
656 * The client may also use unicast to send DHCPINFORM messages
657 * to a known DHCP server. If the client receives no response to DHCP
658 * messages sent to the IP address of a known DHCP server, the DHCP
659 * client reverts to using the IP broadcast address.
662 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
664 return udhcp_send_raw_packet(packet,
665 /*src*/ INADDR_ANY, CLIENT_PORT,
666 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
667 client_config.ifindex);
670 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
673 return udhcp_send_kernel_packet(packet,
675 server, SERVER_PORT);
676 return raw_bcast_from_client_config_ifindex(packet);
679 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
680 /* NOINLINE: limit stack usage in caller */
681 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
683 struct dhcp_packet packet;
685 /* Fill in: op, htype, hlen, cookie, chaddr fields,
686 * random xid field (we override it below),
687 * client-id option (unless -C), message type option:
689 init_packet(&packet, DHCPDISCOVER);
693 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
695 /* Add options: maxsize,
696 * optionally: hostname, fqdn, vendorclass,
697 * "param req" option according to -O, options specified with -x
699 add_client_options(&packet);
701 bb_info_msg("Sending discover...");
702 return raw_bcast_from_client_config_ifindex(&packet);
705 /* Broadcast a DHCP request message */
706 /* RFC 2131 3.1 paragraph 3:
707 * "The client _broadcasts_ a DHCPREQUEST message..."
709 /* NOINLINE: limit stack usage in caller */
710 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
712 struct dhcp_packet packet;
716 * RFC 2131 4.3.2 DHCPREQUEST message
718 * If the DHCPREQUEST message contains a 'server identifier'
719 * option, the message is in response to a DHCPOFFER message.
720 * Otherwise, the message is a request to verify or extend an
721 * existing lease. If the client uses a 'client identifier'
722 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
723 * in all subsequent messages. If the client included a list
724 * of requested parameters in a DHCPDISCOVER message, it MUST
725 * include that list in all subsequent messages.
727 /* Fill in: op, htype, hlen, cookie, chaddr fields,
728 * random xid field (we override it below),
729 * client-id option (unless -C), message type option:
731 init_packet(&packet, DHCPREQUEST);
734 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
736 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
738 /* Add options: maxsize,
739 * optionally: hostname, fqdn, vendorclass,
740 * "param req" option according to -O, and options specified with -x
742 add_client_options(&packet);
744 addr.s_addr = requested;
745 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
746 return raw_bcast_from_client_config_ifindex(&packet);
749 /* Unicast or broadcast a DHCP renew message */
750 /* NOINLINE: limit stack usage in caller */
751 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
753 struct dhcp_packet packet;
756 * RFC 2131 4.3.2 DHCPREQUEST message
758 * DHCPREQUEST generated during RENEWING state:
760 * 'server identifier' MUST NOT be filled in, 'requested IP address'
761 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
762 * client's IP address. In this situation, the client is completely
763 * configured, and is trying to extend its lease. This message will
764 * be unicast, so no relay agents will be involved in its
765 * transmission. Because 'giaddr' is therefore not filled in, the
766 * DHCP server will trust the value in 'ciaddr', and use it when
767 * replying to the client.
769 /* Fill in: op, htype, hlen, cookie, chaddr fields,
770 * random xid field (we override it below),
771 * client-id option (unless -C), message type option:
773 init_packet(&packet, DHCPREQUEST);
776 packet.ciaddr = ciaddr;
778 /* Add options: maxsize,
779 * optionally: hostname, fqdn, vendorclass,
780 * "param req" option according to -O, and options specified with -x
782 add_client_options(&packet);
784 bb_info_msg("Sending renew...");
785 return bcast_or_ucast(&packet, ciaddr, server);
788 #if ENABLE_FEATURE_UDHCPC_ARPING
789 /* Broadcast a DHCP decline message */
790 /* NOINLINE: limit stack usage in caller */
791 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
793 struct dhcp_packet packet;
795 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
796 * client-id option (unless -C), message type option:
798 init_packet(&packet, DHCPDECLINE);
801 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
802 * but in case the server is buggy and wants DHCPDECLINE's xid
803 * to match the xid which started entire handshake,
804 * we use the same xid we used in initial DHCPDISCOVER:
808 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
809 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
811 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
813 bb_info_msg("Sending decline...");
814 return raw_bcast_from_client_config_ifindex(&packet);
818 /* Unicast a DHCP release message */
819 static int send_release(uint32_t server, uint32_t ciaddr)
821 struct dhcp_packet packet;
823 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
824 * client-id option (unless -C), message type option:
826 init_packet(&packet, DHCPRELEASE);
828 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
829 packet.ciaddr = ciaddr;
831 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
833 bb_info_msg("Sending release...");
834 /* Note: normally we unicast here since "server" is not zero.
835 * However, there _are_ people who run "address-less" DHCP servers,
836 * and reportedly ISC dhcp client and Windows allow that.
838 return bcast_or_ucast(&packet, ciaddr, server);
841 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
842 /* NOINLINE: limit stack usage in caller */
843 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
846 struct ip_udp_dhcp_packet packet;
848 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
851 struct cmsghdr *cmsg;
853 /* used to use just safe_read(fd, &packet, sizeof(packet))
854 * but we need to check for TP_STATUS_CSUMNOTREADY :(
856 iov.iov_base = &packet;
857 iov.iov_len = sizeof(packet);
858 memset(&msg, 0, sizeof(msg));
861 msg.msg_control = cmsgbuf;
862 msg.msg_controllen = sizeof(cmsgbuf);
864 bytes = recvmsg(fd, &msg, 0);
868 log1("Packet read error, ignoring");
869 /* NB: possible down interface, etc. Caller should pause. */
870 return bytes; /* returns -1 */
875 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
876 log1("Packet is too short, ignoring");
880 if (bytes < ntohs(packet.ip.tot_len)) {
881 /* packet is bigger than sizeof(packet), we did partial read */
882 log1("Oversized packet, ignoring");
886 /* ignore any extra garbage bytes */
887 bytes = ntohs(packet.ip.tot_len);
889 /* make sure its the right packet for us, and that it passes sanity checks */
890 if (packet.ip.protocol != IPPROTO_UDP
891 || packet.ip.version != IPVERSION
892 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
893 || packet.udp.dest != htons(CLIENT_PORT)
894 /* || bytes > (int) sizeof(packet) - can't happen */
895 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
897 log1("Unrelated/bogus packet, ignoring");
901 /* verify IP checksum */
902 check = packet.ip.check;
904 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
905 log1("Bad IP header checksum, ignoring");
909 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
910 if (cmsg->cmsg_level == SOL_PACKET
911 && cmsg->cmsg_type == PACKET_AUXDATA
913 /* some VMs don't checksum UDP and TCP data
914 * they send to the same physical machine,
915 * here we detect this case:
917 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
918 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
919 goto skip_udp_sum_check;
923 /* verify UDP checksum. IP header has to be modified for this */
924 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
925 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
926 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
927 check = packet.udp.check;
928 packet.udp.check = 0;
929 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
930 log1("Packet with bad UDP checksum received, ignoring");
935 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
936 bb_info_msg("Packet with bad magic, ignoring");
940 log1("Received a packet");
941 udhcp_dump_packet(&packet.data);
943 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
944 memcpy(dhcp_pkt, &packet.data, bytes);
951 static int sockfd = -1;
953 #define LISTEN_NONE 0
954 #define LISTEN_KERNEL 1
956 static smallint listen_mode;
958 /* initial state: (re)start DHCP negotiation */
959 #define INIT_SELECTING 0
960 /* discover was sent, DHCPOFFER reply received */
962 /* select/renew was sent, DHCPACK reply received */
964 /* half of lease passed, want to renew it by sending unicast renew requests */
966 /* renew requests were not answered, lease is almost over, send broadcast renew */
968 /* manually requested renew (SIGUSR1) */
969 #define RENEW_REQUESTED 5
970 /* release, possibly manually requested (SIGUSR2) */
972 static smallint state;
974 static int udhcp_raw_socket(int ifindex)
977 struct sockaddr_ll sock;
979 log1("Opening raw socket on ifindex %d", ifindex); //log2?
981 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
983 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
984 * ETH_P_IP: want to receive only packets with IPv4 eth type
986 log1("Got raw socket fd"); //log2?
988 sock.sll_family = AF_PACKET;
989 sock.sll_protocol = htons(ETH_P_IP);
990 sock.sll_ifindex = ifindex;
991 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
993 #if 0 /* Several users reported breakage when BPF filter is used */
994 if (CLIENT_PORT == 68) {
995 /* Use only if standard port is in use */
997 * I've selected not to see LL header, so BPF doesn't see it, too.
998 * The filter may also pass non-IP and non-ARP packets, but we do
999 * a more complete check when receiving the message in userspace.
1001 * and filter shamelessly stolen from:
1003 * http://www.flamewarmaster.de/software/dhcpclient/
1005 * There are a few other interesting ideas on that page (look under
1006 * "Motivation"). Use of netlink events is most interesting. Think
1007 * of various network servers listening for events and reconfiguring.
1008 * That would obsolete sending HUP signals and/or make use of restarts.
1010 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1013 static const struct sock_filter filter_instr[] = {
1014 /* load 9th byte (protocol) */
1015 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1016 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1017 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1018 /* L1: load halfword from offset 6 (flags and frag offset) */
1019 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1020 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1021 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1022 /* L2: skip IP header (load index reg with header len) */
1023 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1024 /* load udp destination port from halfword[header_len + 2] */
1025 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1026 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1027 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1028 /* L3: accept packet ("accept 0x7fffffff bytes") */
1029 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1030 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1031 /* L4: discard packet ("accept zero bytes") */
1032 BPF_STMT(BPF_RET|BPF_K, 0),
1034 static const struct sock_fprog filter_prog = {
1035 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1036 /* casting const away: */
1037 .filter = (struct sock_filter *) filter_instr,
1039 /* Ignoring error (kernel may lack support for this) */
1040 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1041 sizeof(filter_prog)) >= 0)
1042 log1("Attached filter to raw socket fd"); // log?
1046 if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
1047 &const_int_1, sizeof(int)) < 0
1049 if (errno != ENOPROTOOPT)
1050 log1("Can't set PACKET_AUXDATA on raw socket");
1053 log1("Created raw socket");
1058 static void change_listen_mode(int new_mode)
1060 log1("Entering listen mode: %s",
1061 new_mode != LISTEN_NONE
1062 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1066 listen_mode = new_mode;
1071 if (new_mode == LISTEN_KERNEL)
1072 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1073 else if (new_mode != LISTEN_NONE)
1074 sockfd = udhcp_raw_socket(client_config.ifindex);
1075 /* else LISTEN_NONE: sockfd stays closed */
1078 /* Called only on SIGUSR1 */
1079 static void perform_renew(void)
1081 bb_info_msg("Performing a DHCP renew");
1084 change_listen_mode(LISTEN_KERNEL);
1087 state = RENEW_REQUESTED;
1089 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1090 udhcp_run_script(NULL, "deconfig");
1093 change_listen_mode(LISTEN_RAW);
1094 state = INIT_SELECTING;
1096 case INIT_SELECTING:
1101 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1103 char buffer[sizeof("255.255.255.255")];
1104 struct in_addr temp_addr;
1106 /* send release packet */
1107 if (state == BOUND || state == RENEWING || state == REBINDING) {
1108 temp_addr.s_addr = server_addr;
1109 strcpy(buffer, inet_ntoa(temp_addr));
1110 temp_addr.s_addr = requested_ip;
1111 bb_info_msg("Unicasting a release of %s to %s",
1112 inet_ntoa(temp_addr), buffer);
1113 send_release(server_addr, requested_ip); /* unicast */
1114 udhcp_run_script(NULL, "deconfig");
1116 bb_info_msg("Entering released state");
1118 change_listen_mode(LISTEN_NONE);
1122 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1125 int len = strnlen(str, 255);
1126 storage = xzalloc(len + extra + OPT_DATA);
1127 storage[OPT_CODE] = code;
1128 storage[OPT_LEN] = len + extra;
1129 memcpy(storage + extra + OPT_DATA, str, len);
1134 static void client_background(void)
1137 logmode &= ~LOGMODE_STDIO;
1138 /* rewrite pidfile, as our pid is different now */
1139 write_pidfile(client_config.pidfile);
1143 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1144 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1146 //usage:# define IF_UDHCP_VERBOSE(...)
1148 //usage:#define udhcpc_trivial_usage
1149 //usage: "[-fbq"IF_UDHCP_VERBOSE("v")IF_FEATURE_UDHCPC_ARPING("a")"RB] [-t N] [-T SEC] [-A SEC/-n]\n"
1150 //usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1151 //usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1152 //usage:#define udhcpc_full_usage "\n"
1153 //usage: IF_LONG_OPTS(
1154 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1155 //usage: IF_FEATURE_UDHCP_PORT(
1156 //usage: "\n -P,--client-port PORT Use PORT (default 68)"
1158 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1159 //usage: "\n -p,--pidfile FILE Create pidfile"
1160 //usage: "\n -B,--broadcast Request broadcast replies"
1161 //usage: "\n -t,--retries N Send up to N discover packets (default 3)"
1162 //usage: "\n -T,--timeout SEC Pause between packets (default 3)"
1163 //usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
1164 //usage: "\n -n,--now Exit if lease is not obtained"
1165 //usage: "\n -q,--quit Exit after obtaining lease"
1166 //usage: "\n -R,--release Release IP on exit"
1167 //usage: "\n -f,--foreground Run in foreground"
1168 //usage: USE_FOR_MMU(
1169 //usage: "\n -b,--background Background if lease is not obtained"
1171 //usage: "\n -S,--syslog Log to syslog too"
1172 //usage: IF_FEATURE_UDHCPC_ARPING(
1173 //usage: "\n -a,--arping Use arping to validate offered address"
1175 //usage: "\n -r,--request IP Request this IP address"
1176 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1177 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1178 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1179 //usage: "\n Examples of string, numeric, and hex byte opts:"
1180 //usage: "\n -x hostname:bbox - option 12"
1181 //usage: "\n -x lease:3600 - option 51 (lease time)"
1182 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1183 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1184 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1185 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1186 //usage: IF_UDHCP_VERBOSE(
1187 //usage: "\n -v Verbose"
1190 //usage: IF_NOT_LONG_OPTS(
1191 //usage: "\n -i IFACE Interface to use (default eth0)"
1192 //usage: IF_FEATURE_UDHCP_PORT(
1193 //usage: "\n -P PORT Use PORT (default 68)"
1195 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1196 //usage: "\n -p FILE Create pidfile"
1197 //usage: "\n -B Request broadcast replies"
1198 //usage: "\n -t N Send up to N discover packets (default 3)"
1199 //usage: "\n -T SEC Pause between packets (default 3)"
1200 //usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1201 //usage: "\n -n Exit if lease is not obtained"
1202 //usage: "\n -q Exit after obtaining lease"
1203 //usage: "\n -R Release IP on exit"
1204 //usage: "\n -f Run in foreground"
1205 //usage: USE_FOR_MMU(
1206 //usage: "\n -b Background if lease is not obtained"
1208 //usage: "\n -S Log to syslog too"
1209 //usage: IF_FEATURE_UDHCPC_ARPING(
1210 //usage: "\n -a Use arping to validate offered address"
1212 //usage: "\n -r IP Request this IP address"
1213 //usage: "\n -o Don't request any options (unless -O is given)"
1214 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1215 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1216 //usage: "\n Examples of string, numeric, and hex byte opts:"
1217 //usage: "\n -x hostname:bbox - option 12"
1218 //usage: "\n -x lease:3600 - option 51 (lease time)"
1219 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1220 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1221 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1222 //usage: "\n -C Don't send MAC as client identifier"
1223 //usage: IF_UDHCP_VERBOSE(
1224 //usage: "\n -v Verbose"
1227 //usage: "\nSignals:"
1228 //usage: "\n USR1 Renew lease"
1229 //usage: "\n USR2 Release lease"
1232 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1233 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1236 const char *str_V, *str_h, *str_F, *str_r;
1237 IF_FEATURE_UDHCP_PORT(char *str_P;)
1238 void *clientid_mac_ptr;
1239 llist_t *list_O = NULL;
1240 llist_t *list_x = NULL;
1241 int tryagain_timeout = 20;
1242 int discover_timeout = 3;
1243 int discover_retries = 3;
1244 uint32_t server_addr = server_addr; /* for compiler */
1245 uint32_t requested_ip = 0;
1246 uint32_t xid = xid; /* for compiler */
1248 int timeout; /* must be signed */
1249 unsigned already_waited_sec;
1255 /* Default options */
1256 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1257 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1258 client_config.interface = "eth0";
1259 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1260 str_V = "udhcp "BB_VER;
1262 /* Parse command line */
1263 /* O,x: list; -T,-t,-A take numeric param */
1264 opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1265 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1266 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1268 IF_FEATURE_UDHCPC_ARPING("a")
1269 IF_FEATURE_UDHCP_PORT("P:")
1271 , &str_V, &str_h, &str_h, &str_F
1272 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1273 , &client_config.script /* s */
1274 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1277 IF_FEATURE_UDHCP_PORT(, &str_P)
1278 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1280 if (opt & (OPT_h|OPT_H)) {
1282 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1283 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1286 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1287 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1288 /* Flag bits: 0000NEOS
1289 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1290 * O: 1 = Server indicates to client that DNS has been updated regardless
1291 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1292 * not "host.domain.com". Format 0 is obsolete.
1293 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1294 * Two [0] bytes which follow are deprecated and must be 0.
1296 client_config.fqdn[OPT_DATA + 0] = 0x1;
1297 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1298 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1301 requested_ip = inet_addr(str_r);
1302 #if ENABLE_FEATURE_UDHCP_PORT
1304 CLIENT_PORT = xatou16(str_P);
1305 SERVER_PORT = CLIENT_PORT - 1;
1309 char *optstr = llist_pop(&list_O);
1310 unsigned n = bb_strtou(optstr, NULL, 0);
1311 if (errno || n > 254) {
1312 n = udhcp_option_idx(optstr);
1313 n = dhcp_optflags[n].code;
1315 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1317 if (!(opt & OPT_o)) {
1319 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1320 if (dhcp_optflags[i].flags & OPTION_REQ) {
1321 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1326 char *optstr = llist_pop(&list_x);
1327 char *colon = strchr(optstr, ':');
1330 /* now it looks similar to udhcpd's config file line:
1331 * "optname optval", using the common routine: */
1332 udhcp_str2optset(optstr, &client_config.options);
1335 if (udhcp_read_interface(client_config.interface,
1336 &client_config.ifindex,
1338 client_config.client_mac)
1343 clientid_mac_ptr = NULL;
1344 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1345 /* not suppressed and not set, set the default client ID */
1346 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1347 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1348 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1349 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1351 if (str_V[0] != '\0') {
1352 // can drop -V, str_V, client_config.vendorclass,
1353 // but need to add "vendor" to the list of recognized
1354 // string opts for this to work;
1355 // and need to tweak add_client_options() too...
1356 // ...so the question is, should we?
1357 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1358 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1362 /* on NOMMU reexec (i.e., background) early */
1363 if (!(opt & OPT_f)) {
1364 bb_daemonize_or_rexec(0 /* flags */, argv);
1365 logmode = LOGMODE_NONE;
1369 openlog(applet_name, LOG_PID, LOG_DAEMON);
1370 logmode |= LOGMODE_SYSLOG;
1373 /* Make sure fd 0,1,2 are open */
1374 bb_sanitize_stdio();
1375 /* Equivalent of doing a fflush after every \n */
1377 /* Create pidfile */
1378 write_pidfile(client_config.pidfile);
1379 /* Goes to stdout (unless NOMMU) and possibly syslog */
1380 bb_info_msg("%s (v"BB_VER") started", applet_name);
1381 /* Set up the signal pipe */
1383 /* We want random_xid to be random... */
1384 srand(monotonic_us());
1386 state = INIT_SELECTING;
1387 udhcp_run_script(NULL, "deconfig");
1388 change_listen_mode(LISTEN_RAW);
1391 already_waited_sec = 0;
1393 /* Main event loop. select() waits on signal pipe and possibly
1395 * "continue" statements in code below jump to the top of the loop.
1399 struct dhcp_packet packet;
1400 /* silence "uninitialized!" warning */
1401 unsigned timestamp_before_wait = timestamp_before_wait;
1403 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1405 /* Was opening raw or udp socket here
1406 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1407 * but on fast network renew responses return faster
1408 * than we open sockets. Thus this code is moved
1409 * to change_listen_mode(). Thus we open listen socket
1410 * BEFORE we send renew request (see "case BOUND:"). */
1412 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1414 tv.tv_sec = timeout - already_waited_sec;
1417 /* If we already timed out, fall through with retval = 0, else... */
1418 if ((int)tv.tv_sec > 0) {
1419 log1("Waiting on select %u seconds", (int)tv.tv_sec);
1420 timestamp_before_wait = (unsigned)monotonic_sec();
1421 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1423 /* EINTR? A signal was caught, don't panic */
1424 if (errno == EINTR) {
1425 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1428 /* Else: an error occured, panic! */
1429 bb_perror_msg_and_die("select");
1433 /* If timeout dropped to zero, time to become active:
1434 * resend discover/renew/whatever
1437 /* When running on a bridge, the ifindex may have changed
1438 * (e.g. if member interfaces were added/removed
1439 * or if the status of the bridge changed).
1440 * Refresh ifindex and client_mac:
1442 if (udhcp_read_interface(client_config.interface,
1443 &client_config.ifindex,
1445 client_config.client_mac)
1447 goto ret0; /* iface is gone? */
1449 if (clientid_mac_ptr)
1450 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1452 /* We will restart the wait in any case */
1453 already_waited_sec = 0;
1456 case INIT_SELECTING:
1457 if (!discover_retries || packet_num < discover_retries) {
1458 if (packet_num == 0)
1461 send_discover(xid, requested_ip);
1462 timeout = discover_timeout;
1467 udhcp_run_script(NULL, "leasefail");
1468 #if BB_MMU /* -b is not supported on NOMMU */
1469 if (opt & OPT_b) { /* background if no lease */
1470 bb_info_msg("No lease, forking to background");
1471 client_background();
1472 /* do not background again! */
1473 opt = ((opt & ~OPT_b) | OPT_f);
1476 if (opt & OPT_n) { /* abort if no lease */
1477 bb_info_msg("No lease, failing");
1481 /* wait before trying again */
1482 timeout = tryagain_timeout;
1486 if (!discover_retries || packet_num < discover_retries) {
1487 /* send broadcast select packet */
1488 send_select(xid, server_addr, requested_ip);
1489 timeout = discover_timeout;
1493 /* Timed out, go back to init state.
1494 * "discover...select...discover..." loops
1495 * were seen in the wild. Treat them similarly
1496 * to "no response to discover" case */
1497 change_listen_mode(LISTEN_RAW);
1498 state = INIT_SELECTING;
1501 /* 1/2 lease passed, enter renewing state */
1503 client_config.first_secs = 0; /* make secs field count from 0 */
1504 change_listen_mode(LISTEN_KERNEL);
1505 log1("Entering renew state");
1506 /* fall right through */
1507 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1508 case_RENEW_REQUESTED:
1511 /* send an unicast renew request */
1512 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1513 * a new UDP socket for sending inside send_renew.
1514 * I hazard to guess existing listening socket
1515 * is somehow conflicting with it, but why is it
1516 * not deterministic then?! Strange.
1517 * Anyway, it does recover by eventually failing through
1518 * into INIT_SELECTING state.
1520 send_renew(xid, server_addr, requested_ip);
1524 /* Timed out, enter rebinding state */
1525 log1("Entering rebinding state");
1527 /* fall right through */
1529 /* Switch to bcast receive */
1530 change_listen_mode(LISTEN_RAW);
1531 /* Lease is *really* about to run out,
1532 * try to find DHCP server using broadcast */
1534 /* send a broadcast renew request */
1535 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1539 /* Timed out, enter init state */
1540 bb_info_msg("Lease lost, entering init state");
1541 udhcp_run_script(NULL, "deconfig");
1542 state = INIT_SELECTING;
1543 client_config.first_secs = 0; /* make secs field count from 0 */
1544 /*timeout = 0; - already is */
1547 /* case RELEASED: */
1549 /* yah, I know, *you* say it would never happen */
1551 continue; /* back to main loop */
1552 } /* if select timed out */
1554 /* select() didn't timeout, something happened */
1556 /* Is it a signal? */
1557 /* note: udhcp_sp_read checks FD_ISSET before reading */
1558 switch (udhcp_sp_read(&rfds)) {
1560 client_config.first_secs = 0; /* make secs field count from 0 */
1561 already_waited_sec = 0;
1563 if (state == RENEW_REQUESTED) {
1564 /* We might be either on the same network
1565 * (in which case renew might work),
1566 * or we might be on a completely different one
1567 * (in which case renew won't ever succeed).
1568 * For the second case, must make sure timeout
1569 * is not too big, or else we can send
1570 * futile renew requests for hours.
1571 * (Ab)use -A TIMEOUT value (usually 20 sec)
1572 * as a cap on the timeout.
1574 if (timeout > tryagain_timeout)
1575 timeout = tryagain_timeout;
1576 goto case_RENEW_REQUESTED;
1578 /* Start things over */
1580 /* Kill any timeouts, user wants this to hurry along */
1584 perform_release(server_addr, requested_ip);
1588 bb_info_msg("Received SIGTERM");
1592 /* Is it a packet? */
1593 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1599 /* A packet is ready, read it */
1600 if (listen_mode == LISTEN_KERNEL)
1601 len = udhcp_recv_kernel_packet(&packet, sockfd);
1603 len = udhcp_recv_raw_packet(&packet, sockfd);
1605 /* Error is severe, reopen socket */
1606 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1607 sleep(discover_timeout); /* 3 seconds by default */
1608 change_listen_mode(listen_mode); /* just close and reopen */
1610 /* If this packet will turn out to be unrelated/bogus,
1611 * we will go back and wait for next one.
1612 * Be sure timeout is properly decreased. */
1613 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1618 if (packet.xid != xid) {
1619 log1("xid %x (our is %x), ignoring packet",
1620 (unsigned)packet.xid, (unsigned)xid);
1624 /* Ignore packets that aren't for us */
1625 if (packet.hlen != 6
1626 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1628 //FIXME: need to also check that last 10 bytes are zero
1629 log1("chaddr does not match, ignoring packet"); // log2?
1633 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1634 if (message == NULL) {
1635 bb_error_msg("no message type option, ignoring packet");
1640 case INIT_SELECTING:
1641 /* Must be a DHCPOFFER */
1642 if (*message == DHCPOFFER) {
1645 /* What exactly is server's IP? There are several values.
1646 * Example DHCP offer captured with tchdump:
1648 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1650 * Your-IP 10.34.25.202
1651 * Server-IP 10.34.32.125 // "next server" IP
1652 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1654 * DHCP-Message Option 53, length 1: Offer
1655 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1656 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1658 * We think that real server IP (one to use in renew/release)
1659 * is one in Server-ID option. But I am not 100% sure.
1660 * IP header's src and Gateway-IP (same in this example)
1662 * "Next server" and router are definitely wrong ones to use, though...
1664 /* We used to ignore pcakets without DHCP_SERVER_ID.
1665 * I've got user reports from people who run "address-less" servers.
1666 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1667 * They say ISC DHCP client supports this case.
1670 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1672 bb_error_msg("no server ID, using 0.0.0.0");
1674 /* it IS unaligned sometimes, don't "optimize" */
1675 move_from_unaligned32(server_addr, temp);
1677 /*xid = packet.xid; - already is */
1678 requested_ip = packet.yiaddr;
1680 /* enter requesting state */
1684 already_waited_sec = 0;
1689 case RENEW_REQUESTED:
1691 if (*message == DHCPACK) {
1692 uint32_t lease_seconds;
1693 struct in_addr temp_addr;
1696 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1698 bb_error_msg("no lease time with ACK, using 1 hour lease");
1699 lease_seconds = 60 * 60;
1701 /* it IS unaligned sometimes, don't "optimize" */
1702 move_from_unaligned32(lease_seconds, temp);
1703 lease_seconds = ntohl(lease_seconds);
1704 /* paranoia: must not be too small and not prone to overflows */
1705 if (lease_seconds < 0x10)
1706 lease_seconds = 0x10;
1707 if (lease_seconds >= 0x10000000)
1708 lease_seconds = 0x0fffffff;
1710 #if ENABLE_FEATURE_UDHCPC_ARPING
1712 /* RFC 2131 3.1 paragraph 5:
1713 * "The client receives the DHCPACK message with configuration
1714 * parameters. The client SHOULD perform a final check on the
1715 * parameters (e.g., ARP for allocated network address), and notes
1716 * the duration of the lease specified in the DHCPACK message. At this
1717 * point, the client is configured. If the client detects that the
1718 * address is already in use (e.g., through the use of ARP),
1719 * the client MUST send a DHCPDECLINE message to the server and restarts
1720 * the configuration process..." */
1721 if (!arpping(packet.yiaddr,
1724 client_config.client_mac,
1725 client_config.interface)
1727 bb_info_msg("Offered address is in use "
1728 "(got ARP reply), declining");
1729 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1731 if (state != REQUESTING)
1732 udhcp_run_script(NULL, "deconfig");
1733 change_listen_mode(LISTEN_RAW);
1734 state = INIT_SELECTING;
1735 client_config.first_secs = 0; /* make secs field count from 0 */
1737 timeout = tryagain_timeout;
1739 already_waited_sec = 0;
1740 continue; /* back to main loop */
1744 /* enter bound state */
1745 timeout = lease_seconds / 2;
1746 temp_addr.s_addr = packet.yiaddr;
1747 bb_info_msg("Lease of %s obtained, lease time %u",
1748 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1749 requested_ip = packet.yiaddr;
1750 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1753 change_listen_mode(LISTEN_NONE);
1754 if (opt & OPT_q) { /* quit after lease */
1757 /* future renew failures should not exit (JM) */
1759 #if BB_MMU /* NOMMU case backgrounded earlier */
1760 if (!(opt & OPT_f)) {
1761 client_background();
1762 /* do not background again! */
1763 opt = ((opt & ~OPT_b) | OPT_f);
1766 /* make future renew packets use different xid */
1767 /* xid = random_xid(); ...but why bother? */
1768 already_waited_sec = 0;
1769 continue; /* back to main loop */
1771 if (*message == DHCPNAK) {
1772 /* If network has more than one DHCP server,
1773 * "wrong" server can reply first, with a NAK.
1774 * Do not interpret it as a NAK from "our" server.
1776 if (server_addr != 0) {
1780 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1783 log1("%s with wrong server ID, ignoring packet",
1788 move_from_unaligned32(svid, temp);
1789 if (svid != server_addr)
1790 goto non_matching_svid;
1792 /* return to init state */
1793 bb_info_msg("Received DHCP NAK");
1794 udhcp_run_script(&packet, "nak");
1795 if (state != REQUESTING)
1796 udhcp_run_script(NULL, "deconfig");
1797 change_listen_mode(LISTEN_RAW);
1798 sleep(3); /* avoid excessive network traffic */
1799 state = INIT_SELECTING;
1800 client_config.first_secs = 0; /* make secs field count from 0 */
1804 already_waited_sec = 0;
1807 /* case BOUND: - ignore all packets */
1808 /* case RELEASED: - ignore all packets */
1810 /* back to main loop */
1811 } /* for (;;) - main loop ends */
1814 if (opt & OPT_R) /* release on quit */
1815 perform_release(server_addr, requested_ip);
1818 /*if (client_config.pidfile) - remove_pidfile has its own check */
1819 remove_pidfile(client_config.pidfile);