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 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
671 /* NOINLINE: limit stack usage in caller */
672 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
674 struct dhcp_packet packet;
676 /* Fill in: op, htype, hlen, cookie, chaddr fields,
677 * random xid field (we override it below),
678 * client-id option (unless -C), message type option:
680 init_packet(&packet, DHCPDISCOVER);
684 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
686 /* Add options: maxsize,
687 * optionally: hostname, fqdn, vendorclass,
688 * "param req" option according to -O, options specified with -x
690 add_client_options(&packet);
692 bb_info_msg("Sending discover...");
693 return raw_bcast_from_client_config_ifindex(&packet);
696 /* Broadcast a DHCP request message */
697 /* RFC 2131 3.1 paragraph 3:
698 * "The client _broadcasts_ a DHCPREQUEST message..."
700 /* NOINLINE: limit stack usage in caller */
701 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
703 struct dhcp_packet packet;
707 * RFC 2131 4.3.2 DHCPREQUEST message
709 * If the DHCPREQUEST message contains a 'server identifier'
710 * option, the message is in response to a DHCPOFFER message.
711 * Otherwise, the message is a request to verify or extend an
712 * existing lease. If the client uses a 'client identifier'
713 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
714 * in all subsequent messages. If the client included a list
715 * of requested parameters in a DHCPDISCOVER message, it MUST
716 * include that list in all subsequent messages.
718 /* Fill in: op, htype, hlen, cookie, chaddr fields,
719 * random xid field (we override it below),
720 * client-id option (unless -C), message type option:
722 init_packet(&packet, DHCPREQUEST);
725 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
727 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
729 /* Add options: maxsize,
730 * optionally: hostname, fqdn, vendorclass,
731 * "param req" option according to -O, and options specified with -x
733 add_client_options(&packet);
735 addr.s_addr = requested;
736 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
737 return raw_bcast_from_client_config_ifindex(&packet);
740 /* Unicast or broadcast a DHCP renew message */
741 /* NOINLINE: limit stack usage in caller */
742 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
744 struct dhcp_packet packet;
747 * RFC 2131 4.3.2 DHCPREQUEST message
749 * DHCPREQUEST generated during RENEWING state:
751 * 'server identifier' MUST NOT be filled in, 'requested IP address'
752 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
753 * client's IP address. In this situation, the client is completely
754 * configured, and is trying to extend its lease. This message will
755 * be unicast, so no relay agents will be involved in its
756 * transmission. Because 'giaddr' is therefore not filled in, the
757 * DHCP server will trust the value in 'ciaddr', and use it when
758 * replying to the client.
760 /* Fill in: op, htype, hlen, cookie, chaddr fields,
761 * random xid field (we override it below),
762 * client-id option (unless -C), message type option:
764 init_packet(&packet, DHCPREQUEST);
767 packet.ciaddr = ciaddr;
769 /* Add options: maxsize,
770 * optionally: hostname, fqdn, vendorclass,
771 * "param req" option according to -O, and options specified with -x
773 add_client_options(&packet);
775 bb_info_msg("Sending renew...");
777 return udhcp_send_kernel_packet(&packet,
779 server, SERVER_PORT);
780 return raw_bcast_from_client_config_ifindex(&packet);
783 #if ENABLE_FEATURE_UDHCPC_ARPING
784 /* Broadcast a DHCP decline message */
785 /* NOINLINE: limit stack usage in caller */
786 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
788 struct dhcp_packet packet;
790 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
791 * client-id option (unless -C), message type option:
793 init_packet(&packet, DHCPDECLINE);
796 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
797 * but in case the server is buggy and wants DHCPDECLINE's xid
798 * to match the xid which started entire handshake,
799 * we use the same xid we used in initial DHCPDISCOVER:
803 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
804 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
806 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
808 bb_info_msg("Sending decline...");
809 return raw_bcast_from_client_config_ifindex(&packet);
813 /* Unicast a DHCP release message */
814 static int send_release(uint32_t server, uint32_t ciaddr)
816 struct dhcp_packet packet;
818 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
819 * client-id option (unless -C), message type option:
821 init_packet(&packet, DHCPRELEASE);
823 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
824 packet.ciaddr = ciaddr;
826 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
828 bb_info_msg("Sending release...");
829 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
832 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
833 /* NOINLINE: limit stack usage in caller */
834 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
837 struct ip_udp_dhcp_packet packet;
839 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
842 struct cmsghdr *cmsg;
844 /* used to use just safe_read(fd, &packet, sizeof(packet))
845 * but we need to check for TP_STATUS_CSUMNOTREADY :(
847 iov.iov_base = &packet;
848 iov.iov_len = sizeof(packet);
849 memset(&msg, 0, sizeof(msg));
852 msg.msg_control = cmsgbuf;
853 msg.msg_controllen = sizeof(cmsgbuf);
855 bytes = recvmsg(fd, &msg, 0);
859 log1("Packet read error, ignoring");
860 /* NB: possible down interface, etc. Caller should pause. */
861 return bytes; /* returns -1 */
866 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
867 log1("Packet is too short, ignoring");
871 if (bytes < ntohs(packet.ip.tot_len)) {
872 /* packet is bigger than sizeof(packet), we did partial read */
873 log1("Oversized packet, ignoring");
877 /* ignore any extra garbage bytes */
878 bytes = ntohs(packet.ip.tot_len);
880 /* make sure its the right packet for us, and that it passes sanity checks */
881 if (packet.ip.protocol != IPPROTO_UDP
882 || packet.ip.version != IPVERSION
883 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
884 || packet.udp.dest != htons(CLIENT_PORT)
885 /* || bytes > (int) sizeof(packet) - can't happen */
886 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
888 log1("Unrelated/bogus packet, ignoring");
892 /* verify IP checksum */
893 check = packet.ip.check;
895 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
896 log1("Bad IP header checksum, ignoring");
900 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
901 if (cmsg->cmsg_level == SOL_PACKET
902 && cmsg->cmsg_type == PACKET_AUXDATA
904 /* some VMs don't checksum UDP and TCP data
905 * they send to the same physical machine,
906 * here we detect this case:
908 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
909 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
910 goto skip_udp_sum_check;
914 /* verify UDP checksum. IP header has to be modified for this */
915 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
916 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
917 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
918 check = packet.udp.check;
919 packet.udp.check = 0;
920 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
921 log1("Packet with bad UDP checksum received, ignoring");
926 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
927 bb_info_msg("Packet with bad magic, ignoring");
931 log1("Received a packet");
932 udhcp_dump_packet(&packet.data);
934 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
935 memcpy(dhcp_pkt, &packet.data, bytes);
942 static int sockfd = -1;
944 #define LISTEN_NONE 0
945 #define LISTEN_KERNEL 1
947 static smallint listen_mode;
949 /* initial state: (re)start DHCP negotiation */
950 #define INIT_SELECTING 0
951 /* discover was sent, DHCPOFFER reply received */
953 /* select/renew was sent, DHCPACK reply received */
955 /* half of lease passed, want to renew it by sending unicast renew requests */
957 /* renew requests were not answered, lease is almost over, send broadcast renew */
959 /* manually requested renew (SIGUSR1) */
960 #define RENEW_REQUESTED 5
961 /* release, possibly manually requested (SIGUSR2) */
963 static smallint state;
965 static int udhcp_raw_socket(int ifindex)
968 struct sockaddr_ll sock;
973 * I've selected not to see LL header, so BPF doesn't see it, too.
974 * The filter may also pass non-IP and non-ARP packets, but we do
975 * a more complete check when receiving the message in userspace.
977 * and filter shamelessly stolen from:
979 * http://www.flamewarmaster.de/software/dhcpclient/
981 * There are a few other interesting ideas on that page (look under
982 * "Motivation"). Use of netlink events is most interesting. Think
983 * of various network servers listening for events and reconfiguring.
984 * That would obsolete sending HUP signals and/or make use of restarts.
986 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
989 * TODO: make conditional?
991 static const struct sock_filter filter_instr[] = {
992 /* load 9th byte (protocol) */
993 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
994 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
995 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
996 /* L1: load halfword from offset 6 (flags and frag offset) */
997 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
998 /* jump to L4 if any bits in frag offset field are set, else to L2 */
999 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1000 /* L2: skip IP header (load index reg with header len) */
1001 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1002 /* load udp destination port from halfword[header_len + 2] */
1003 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1004 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1005 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1006 /* L3: accept packet */
1007 BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
1008 /* L4: discard packet */
1009 BPF_STMT(BPF_RET|BPF_K, 0),
1011 static const struct sock_fprog filter_prog = {
1012 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1013 /* casting const away: */
1014 .filter = (struct sock_filter *) filter_instr,
1017 log1("Opening raw socket on ifindex %d", ifindex); //log2?
1019 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
1020 log1("Got raw socket fd"); //log2?
1022 sock.sll_family = AF_PACKET;
1023 sock.sll_protocol = htons(ETH_P_IP);
1024 sock.sll_ifindex = ifindex;
1025 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1027 if (CLIENT_PORT == 68) {
1028 /* Use only if standard port is in use */
1029 /* Ignoring error (kernel may lack support for this) */
1030 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1031 sizeof(filter_prog)) >= 0)
1032 log1("Attached filter to raw socket fd"); // log?
1035 if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
1036 &const_int_1, sizeof(int)) < 0
1038 if (errno != ENOPROTOOPT)
1039 log1("Can't set PACKET_AUXDATA on raw socket");
1042 log1("Created raw socket");
1047 static void change_listen_mode(int new_mode)
1049 log1("Entering listen mode: %s",
1050 new_mode != LISTEN_NONE
1051 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1055 listen_mode = new_mode;
1060 if (new_mode == LISTEN_KERNEL)
1061 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1062 else if (new_mode != LISTEN_NONE)
1063 sockfd = udhcp_raw_socket(client_config.ifindex);
1064 /* else LISTEN_NONE: sockfd stays closed */
1067 /* Called only on SIGUSR1 */
1068 static void perform_renew(void)
1070 bb_info_msg("Performing a DHCP renew");
1073 change_listen_mode(LISTEN_KERNEL);
1076 state = RENEW_REQUESTED;
1078 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1079 udhcp_run_script(NULL, "deconfig");
1082 change_listen_mode(LISTEN_RAW);
1083 state = INIT_SELECTING;
1085 case INIT_SELECTING:
1090 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1092 char buffer[sizeof("255.255.255.255")];
1093 struct in_addr temp_addr;
1095 /* send release packet */
1096 if (state == BOUND || state == RENEWING || state == REBINDING) {
1097 temp_addr.s_addr = server_addr;
1098 strcpy(buffer, inet_ntoa(temp_addr));
1099 temp_addr.s_addr = requested_ip;
1100 bb_info_msg("Unicasting a release of %s to %s",
1101 inet_ntoa(temp_addr), buffer);
1102 send_release(server_addr, requested_ip); /* unicast */
1103 udhcp_run_script(NULL, "deconfig");
1105 bb_info_msg("Entering released state");
1107 change_listen_mode(LISTEN_NONE);
1111 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1114 int len = strnlen(str, 255);
1115 storage = xzalloc(len + extra + OPT_DATA);
1116 storage[OPT_CODE] = code;
1117 storage[OPT_LEN] = len + extra;
1118 memcpy(storage + extra + OPT_DATA, str, len);
1123 static void client_background(void)
1126 logmode &= ~LOGMODE_STDIO;
1127 /* rewrite pidfile, as our pid is different now */
1128 write_pidfile(client_config.pidfile);
1132 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1133 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1135 //usage:# define IF_UDHCP_VERBOSE(...)
1137 //usage:#define udhcpc_trivial_usage
1138 //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
1139 //usage: " [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
1140 //usage:#define udhcpc_full_usage "\n"
1141 //usage: IF_LONG_OPTS(
1142 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1143 //usage: "\n -p,--pidfile FILE Create pidfile"
1144 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1145 //usage: "\n -B,--broadcast Request broadcast replies"
1146 //usage: "\n -t,--retries N Send up to N discover packets"
1147 //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
1148 //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
1149 //usage: "\n -f,--foreground Run in foreground"
1150 //usage: USE_FOR_MMU(
1151 //usage: "\n -b,--background Background if lease is not obtained"
1153 //usage: "\n -n,--now Exit if lease is not obtained"
1154 //usage: "\n -q,--quit Exit after obtaining lease"
1155 //usage: "\n -R,--release Release IP on exit"
1156 //usage: "\n -S,--syslog Log to syslog too"
1157 //usage: IF_FEATURE_UDHCP_PORT(
1158 //usage: "\n -P,--client-port N Use port N (default 68)"
1160 //usage: IF_FEATURE_UDHCPC_ARPING(
1161 //usage: "\n -a,--arping Use arping to validate offered address"
1163 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1164 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1165 //usage: "\n -r,--request IP Request this IP address"
1166 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1167 //usage: "\n Examples of string, numeric, and hex byte opts:"
1168 //usage: "\n -x hostname:bbox - option 12"
1169 //usage: "\n -x lease:3600 - option 51 (lease time)"
1170 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1171 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1172 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1173 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1174 //usage: IF_UDHCP_VERBOSE(
1175 //usage: "\n -v Verbose"
1178 //usage: IF_NOT_LONG_OPTS(
1179 //usage: "\n -i IFACE Interface to use (default eth0)"
1180 //usage: "\n -p FILE Create pidfile"
1181 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1182 //usage: "\n -B Request broadcast replies"
1183 //usage: "\n -t N Send up to N discover packets"
1184 //usage: "\n -T N Pause between packets (default 3 seconds)"
1185 //usage: "\n -A N Wait N seconds (default 20) after failure"
1186 //usage: "\n -f Run in foreground"
1187 //usage: USE_FOR_MMU(
1188 //usage: "\n -b Background if lease is not obtained"
1190 //usage: "\n -n Exit if lease is not obtained"
1191 //usage: "\n -q Exit after obtaining lease"
1192 //usage: "\n -R Release IP on exit"
1193 //usage: "\n -S Log to syslog too"
1194 //usage: IF_FEATURE_UDHCP_PORT(
1195 //usage: "\n -P N Use port N (default 68)"
1197 //usage: IF_FEATURE_UDHCPC_ARPING(
1198 //usage: "\n -a Use arping to validate offered address"
1200 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1201 //usage: "\n -o Don't request any options (unless -O is given)"
1202 //usage: "\n -r IP Request this IP address"
1203 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1204 //usage: "\n Examples of string, numeric, and hex byte opts:"
1205 //usage: "\n -x hostname:bbox - option 12"
1206 //usage: "\n -x lease:3600 - option 51 (lease time)"
1207 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1208 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1209 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1210 //usage: "\n -C Don't send MAC as client identifier"
1211 //usage: IF_UDHCP_VERBOSE(
1212 //usage: "\n -v Verbose"
1215 //usage: "\nSignals:"
1216 //usage: "\n USR1 Renew lease"
1217 //usage: "\n USR2 Release lease"
1220 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1221 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1223 uint8_t *temp, *message;
1224 const char *str_V, *str_h, *str_F, *str_r;
1225 IF_FEATURE_UDHCP_PORT(char *str_P;)
1226 void *clientid_mac_ptr;
1227 llist_t *list_O = NULL;
1228 llist_t *list_x = NULL;
1229 int tryagain_timeout = 20;
1230 int discover_timeout = 3;
1231 int discover_retries = 3;
1232 uint32_t server_addr = server_addr; /* for compiler */
1233 uint32_t requested_ip = 0;
1234 uint32_t xid = xid; /* for compiler */
1236 int timeout; /* must be signed */
1237 unsigned already_waited_sec;
1243 /* Default options */
1244 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1245 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1246 client_config.interface = "eth0";
1247 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1248 str_V = "udhcp "BB_VER;
1250 /* Parse command line */
1251 /* O,x: list; -T,-t,-A take numeric param */
1252 opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1253 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1254 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1256 IF_FEATURE_UDHCPC_ARPING("a")
1257 IF_FEATURE_UDHCP_PORT("P:")
1259 , &str_V, &str_h, &str_h, &str_F
1260 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1261 , &client_config.script /* s */
1262 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1265 IF_FEATURE_UDHCP_PORT(, &str_P)
1266 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1268 if (opt & (OPT_h|OPT_H)) {
1270 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1271 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1274 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1275 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1276 /* Flag bits: 0000NEOS
1277 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1278 * O: 1 = Server indicates to client that DNS has been updated regardless
1279 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1280 * not "host.domain.com". Format 0 is obsolete.
1281 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1282 * Two [0] bytes which follow are deprecated and must be 0.
1284 client_config.fqdn[OPT_DATA + 0] = 0x1;
1285 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1286 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1289 requested_ip = inet_addr(str_r);
1290 #if ENABLE_FEATURE_UDHCP_PORT
1292 CLIENT_PORT = xatou16(str_P);
1293 SERVER_PORT = CLIENT_PORT - 1;
1297 char *optstr = llist_pop(&list_O);
1298 unsigned n = bb_strtou(optstr, NULL, 0);
1299 if (errno || n > 254) {
1300 n = udhcp_option_idx(optstr);
1301 n = dhcp_optflags[n].code;
1303 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1305 if (!(opt & OPT_o)) {
1307 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1308 if (dhcp_optflags[i].flags & OPTION_REQ) {
1309 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1314 char *optstr = llist_pop(&list_x);
1315 char *colon = strchr(optstr, ':');
1318 /* now it looks similar to udhcpd's config file line:
1319 * "optname optval", using the common routine: */
1320 udhcp_str2optset(optstr, &client_config.options);
1323 if (udhcp_read_interface(client_config.interface,
1324 &client_config.ifindex,
1326 client_config.client_mac)
1331 clientid_mac_ptr = NULL;
1332 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1333 /* not suppressed and not set, set the default client ID */
1334 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1335 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1336 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1337 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1339 if (str_V[0] != '\0') {
1340 // can drop -V, str_V, client_config.vendorclass,
1341 // but need to add "vendor" to the list of recognized
1342 // string opts for this to work;
1343 // and need to tweak add_client_options() too...
1344 // ...so the question is, should we?
1345 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1346 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1350 /* on NOMMU reexec (i.e., background) early */
1351 if (!(opt & OPT_f)) {
1352 bb_daemonize_or_rexec(0 /* flags */, argv);
1353 logmode = LOGMODE_NONE;
1357 openlog(applet_name, LOG_PID, LOG_DAEMON);
1358 logmode |= LOGMODE_SYSLOG;
1361 /* Make sure fd 0,1,2 are open */
1362 bb_sanitize_stdio();
1363 /* Equivalent of doing a fflush after every \n */
1365 /* Create pidfile */
1366 write_pidfile(client_config.pidfile);
1367 /* Goes to stdout (unless NOMMU) and possibly syslog */
1368 bb_info_msg("%s (v"BB_VER") started", applet_name);
1369 /* Set up the signal pipe */
1371 /* We want random_xid to be random... */
1372 srand(monotonic_us());
1374 state = INIT_SELECTING;
1375 udhcp_run_script(NULL, "deconfig");
1376 change_listen_mode(LISTEN_RAW);
1379 already_waited_sec = 0;
1381 /* Main event loop. select() waits on signal pipe and possibly
1383 * "continue" statements in code below jump to the top of the loop.
1387 struct dhcp_packet packet;
1388 /* silence "uninitialized!" warning */
1389 unsigned timestamp_before_wait = timestamp_before_wait;
1391 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1393 /* Was opening raw or udp socket here
1394 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1395 * but on fast network renew responses return faster
1396 * than we open sockets. Thus this code is moved
1397 * to change_listen_mode(). Thus we open listen socket
1398 * BEFORE we send renew request (see "case BOUND:"). */
1400 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1402 tv.tv_sec = timeout - already_waited_sec;
1405 /* If we already timed out, fall through with retval = 0, else... */
1406 if ((int)tv.tv_sec > 0) {
1407 log1("Waiting on select %u seconds", (int)tv.tv_sec);
1408 timestamp_before_wait = (unsigned)monotonic_sec();
1409 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1411 /* EINTR? A signal was caught, don't panic */
1412 if (errno == EINTR) {
1413 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1416 /* Else: an error occured, panic! */
1417 bb_perror_msg_and_die("select");
1421 /* If timeout dropped to zero, time to become active:
1422 * resend discover/renew/whatever
1425 /* When running on a bridge, the ifindex may have changed
1426 * (e.g. if member interfaces were added/removed
1427 * or if the status of the bridge changed).
1428 * Refresh ifindex and client_mac:
1430 if (udhcp_read_interface(client_config.interface,
1431 &client_config.ifindex,
1433 client_config.client_mac)
1435 goto ret0; /* iface is gone? */
1437 if (clientid_mac_ptr)
1438 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1440 /* We will restart the wait in any case */
1441 already_waited_sec = 0;
1444 case INIT_SELECTING:
1445 if (!discover_retries || packet_num < discover_retries) {
1446 if (packet_num == 0)
1449 send_discover(xid, requested_ip);
1450 timeout = discover_timeout;
1455 udhcp_run_script(NULL, "leasefail");
1456 #if BB_MMU /* -b is not supported on NOMMU */
1457 if (opt & OPT_b) { /* background if no lease */
1458 bb_info_msg("No lease, forking to background");
1459 client_background();
1460 /* do not background again! */
1461 opt = ((opt & ~OPT_b) | OPT_f);
1464 if (opt & OPT_n) { /* abort if no lease */
1465 bb_info_msg("No lease, failing");
1469 /* wait before trying again */
1470 timeout = tryagain_timeout;
1474 if (!discover_retries || packet_num < discover_retries) {
1475 /* send broadcast select packet */
1476 send_select(xid, server_addr, requested_ip);
1477 timeout = discover_timeout;
1481 /* Timed out, go back to init state.
1482 * "discover...select...discover..." loops
1483 * were seen in the wild. Treat them similarly
1484 * to "no response to discover" case */
1485 change_listen_mode(LISTEN_RAW);
1486 state = INIT_SELECTING;
1489 /* 1/2 lease passed, enter renewing state */
1491 client_config.first_secs = 0; /* make secs field count from 0 */
1492 change_listen_mode(LISTEN_KERNEL);
1493 log1("Entering renew state");
1494 /* fall right through */
1495 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1496 case_RENEW_REQUESTED:
1499 /* send an unicast renew request */
1500 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1501 * a new UDP socket for sending inside send_renew.
1502 * I hazard to guess existing listening socket
1503 * is somehow conflicting with it, but why is it
1504 * not deterministic then?! Strange.
1505 * Anyway, it does recover by eventually failing through
1506 * into INIT_SELECTING state.
1508 send_renew(xid, server_addr, requested_ip);
1512 /* Timed out, enter rebinding state */
1513 log1("Entering rebinding state");
1515 /* fall right through */
1517 /* Switch to bcast receive */
1518 change_listen_mode(LISTEN_RAW);
1519 /* Lease is *really* about to run out,
1520 * try to find DHCP server using broadcast */
1522 /* send a broadcast renew request */
1523 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1527 /* Timed out, enter init state */
1528 bb_info_msg("Lease lost, entering init state");
1529 udhcp_run_script(NULL, "deconfig");
1530 state = INIT_SELECTING;
1531 client_config.first_secs = 0; /* make secs field count from 0 */
1532 /*timeout = 0; - already is */
1535 /* case RELEASED: */
1537 /* yah, I know, *you* say it would never happen */
1539 continue; /* back to main loop */
1540 } /* if select timed out */
1542 /* select() didn't timeout, something happened */
1544 /* Is it a signal? */
1545 /* note: udhcp_sp_read checks FD_ISSET before reading */
1546 switch (udhcp_sp_read(&rfds)) {
1548 client_config.first_secs = 0; /* make secs field count from 0 */
1549 already_waited_sec = 0;
1551 if (state == RENEW_REQUESTED) {
1552 /* We might be either on the same network
1553 * (in which case renew might work),
1554 * or we might be on a completely different one
1555 * (in which case renew won't ever succeed).
1556 * For the second case, must make sure timeout
1557 * is not too big, or else we can send
1558 * futile renew requests for hours.
1559 * (Ab)use -A TIMEOUT value (usually 20 sec)
1560 * as a cap on the timeout.
1562 if (timeout > tryagain_timeout)
1563 timeout = tryagain_timeout;
1564 goto case_RENEW_REQUESTED;
1566 /* Start things over */
1568 /* Kill any timeouts, user wants this to hurry along */
1572 perform_release(server_addr, requested_ip);
1576 bb_info_msg("Received SIGTERM");
1580 /* Is it a packet? */
1581 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1587 /* A packet is ready, read it */
1588 if (listen_mode == LISTEN_KERNEL)
1589 len = udhcp_recv_kernel_packet(&packet, sockfd);
1591 len = udhcp_recv_raw_packet(&packet, sockfd);
1593 /* Error is severe, reopen socket */
1594 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1595 sleep(discover_timeout); /* 3 seconds by default */
1596 change_listen_mode(listen_mode); /* just close and reopen */
1598 /* If this packet will turn out to be unrelated/bogus,
1599 * we will go back and wait for next one.
1600 * Be sure timeout is properly decreased. */
1601 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1606 if (packet.xid != xid) {
1607 log1("xid %x (our is %x), ignoring packet",
1608 (unsigned)packet.xid, (unsigned)xid);
1612 /* Ignore packets that aren't for us */
1613 if (packet.hlen != 6
1614 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1616 //FIXME: need to also check that last 10 bytes are zero
1617 log1("chaddr does not match, ignoring packet"); // log2?
1621 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1622 if (message == NULL) {
1623 bb_error_msg("no message type option, ignoring packet");
1628 case INIT_SELECTING:
1629 /* Must be a DHCPOFFER */
1630 if (*message == DHCPOFFER) {
1631 /* What exactly is server's IP? There are several values.
1632 * Example DHCP offer captured with tchdump:
1634 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1636 * Your-IP 10.34.25.202
1637 * Server-IP 10.34.32.125 // "next server" IP
1638 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1640 * DHCP-Message Option 53, length 1: Offer
1641 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1642 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1644 * We think that real server IP (one to use in renew/release)
1645 * is one in Server-ID option. But I am not 100% sure.
1646 * IP header's src and Gateway-IP (same in this example)
1648 * "Next server" and router are definitely wrong ones to use, though...
1650 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1652 bb_error_msg("no server ID, ignoring packet");
1654 /* still selecting - this server looks bad */
1656 /* it IS unaligned sometimes, don't "optimize" */
1657 move_from_unaligned32(server_addr, temp);
1658 /*xid = packet.xid; - already is */
1659 requested_ip = packet.yiaddr;
1661 /* enter requesting state */
1665 already_waited_sec = 0;
1670 case RENEW_REQUESTED:
1672 if (*message == DHCPACK) {
1673 uint32_t lease_seconds;
1674 struct in_addr temp_addr;
1676 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1678 bb_error_msg("no lease time with ACK, using 1 hour lease");
1679 lease_seconds = 60 * 60;
1681 /* it IS unaligned sometimes, don't "optimize" */
1682 move_from_unaligned32(lease_seconds, temp);
1683 lease_seconds = ntohl(lease_seconds);
1684 /* paranoia: must not be too small and not prone to overflows */
1685 if (lease_seconds < 0x10)
1686 lease_seconds = 0x10;
1687 if (lease_seconds >= 0x10000000)
1688 lease_seconds = 0x0fffffff;
1690 #if ENABLE_FEATURE_UDHCPC_ARPING
1692 /* RFC 2131 3.1 paragraph 5:
1693 * "The client receives the DHCPACK message with configuration
1694 * parameters. The client SHOULD perform a final check on the
1695 * parameters (e.g., ARP for allocated network address), and notes
1696 * the duration of the lease specified in the DHCPACK message. At this
1697 * point, the client is configured. If the client detects that the
1698 * address is already in use (e.g., through the use of ARP),
1699 * the client MUST send a DHCPDECLINE message to the server and restarts
1700 * the configuration process..." */
1701 if (!arpping(packet.yiaddr,
1704 client_config.client_mac,
1705 client_config.interface)
1707 bb_info_msg("Offered address is in use "
1708 "(got ARP reply), declining");
1709 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1711 if (state != REQUESTING)
1712 udhcp_run_script(NULL, "deconfig");
1713 change_listen_mode(LISTEN_RAW);
1714 state = INIT_SELECTING;
1715 client_config.first_secs = 0; /* make secs field count from 0 */
1717 timeout = tryagain_timeout;
1719 already_waited_sec = 0;
1720 continue; /* back to main loop */
1724 /* enter bound state */
1725 timeout = lease_seconds / 2;
1726 temp_addr.s_addr = packet.yiaddr;
1727 bb_info_msg("Lease of %s obtained, lease time %u",
1728 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1729 requested_ip = packet.yiaddr;
1730 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1733 change_listen_mode(LISTEN_NONE);
1734 if (opt & OPT_q) { /* quit after lease */
1737 /* future renew failures should not exit (JM) */
1739 #if BB_MMU /* NOMMU case backgrounded earlier */
1740 if (!(opt & OPT_f)) {
1741 client_background();
1742 /* do not background again! */
1743 opt = ((opt & ~OPT_b) | OPT_f);
1746 /* make future renew packets use different xid */
1747 /* xid = random_xid(); ...but why bother? */
1748 already_waited_sec = 0;
1749 continue; /* back to main loop */
1751 if (*message == DHCPNAK) {
1752 /* return to init state */
1753 bb_info_msg("Received DHCP NAK");
1754 udhcp_run_script(&packet, "nak");
1755 if (state != REQUESTING)
1756 udhcp_run_script(NULL, "deconfig");
1757 change_listen_mode(LISTEN_RAW);
1758 sleep(3); /* avoid excessive network traffic */
1759 state = INIT_SELECTING;
1760 client_config.first_secs = 0; /* make secs field count from 0 */
1764 already_waited_sec = 0;
1767 /* case BOUND: - ignore all packets */
1768 /* case RELEASED: - ignore all packets */
1770 /* back to main loop */
1771 } /* for (;;) - main loop ends */
1774 if (opt & OPT_R) /* release on quit */
1775 perform_release(server_addr, requested_ip);
1778 /*if (client_config.pidfile) - remove_pidfile has its own check */
1779 remove_pidfile(client_config.pidfile);