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 #if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
140 /* Check if a given label represents a valid DNS label
141 * Return pointer to the first character after the label upon success,
145 /* We don't need to be particularly anal. For example, allowing _, hyphen
146 * at the end, or leading and trailing dots would be ok, since it
147 * can't be used for attacks. (Leading hyphen can be, if someone uses
149 * in the script: then hostname may be treated as an option)
151 static const char *valid_domain_label(const char *label)
158 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
160 /* label must begin with letter */
163 if (ch < '0' || ch > '9') {
164 if (ch == '\0' || ch == '.')
166 /* DNS allows only '-', but we are more permissive */
167 if (ch != '-' && ch != '_')
174 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
179 /* Check if a given name represents a valid DNS name */
180 /* See RFC1035, 2.3.1 */
181 static int good_hostname(const char *name)
183 //const char *start = name;
186 name = valid_domain_label(name);
192 //return ((name - start) < 1025); /* NS_MAXDNAME */
197 # define good_hostname(name) 1
200 /* Create "opt_name=opt_value" string */
201 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
203 unsigned upper_length;
204 int len, type, optlen;
207 /* option points to OPT_DATA, need to go back to get OPT_LEN */
208 len = option[-OPT_DATA + OPT_LEN];
210 type = optflag->flags & OPTION_TYPE_MASK;
211 optlen = dhcp_option_lengths[type];
212 upper_length = len_of_option_as_string[type]
213 * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
215 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
216 dest += sprintf(ret, "%s=", opt_name);
218 while (len >= optlen) {
222 dest += sprint_nip(dest, "", option);
223 if (type == OPTION_IP)
225 dest += sprint_nip(dest, "/", option + 4);
227 // case OPTION_BOOLEAN:
228 // dest += sprintf(dest, *option ? "yes" : "no");
231 dest += sprintf(dest, "%u", *option);
236 move_from_unaligned16(val_u16, option);
237 dest += sprintf(dest, "%u", ntohs(val_u16));
243 move_from_unaligned32(val_u32, option);
244 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
247 /* Note: options which use 'return' instead of 'break'
248 * (for example, OPTION_STRING) skip the code which handles
249 * the case of list of options.
252 case OPTION_STRING_HOST:
253 memcpy(dest, option, len);
255 if (type == OPTION_STRING_HOST && !good_hostname(dest))
256 safe_strncpy(dest, "bad", len);
258 case OPTION_STATIC_ROUTES: {
259 /* Option binary format:
260 * mask [one byte, 0..32]
261 * ip [big endian, 0..4 bytes depending on mask]
262 * router [big endian, 4 bytes]
265 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
267 const char *pfx = "";
269 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
282 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
283 while (--bytes >= 0) {
291 dest += sprint_nip(dest, pfx, (void*) &nip);
293 dest += sprintf(dest, "/%u ", mask);
295 dest += sprint_nip(dest, "", option);
303 /* Option binary format (see RFC 5969):
305 * 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
306 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
307 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
308 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
310 * ... (16 octets) ...
311 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
312 * ... 6rdBRIPv4Address(es) ...
313 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
314 * We convert it to a string
315 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
317 * Sanity check: ensure that our length is at least 22 bytes, that
319 * 6rdPrefixLen <= 128,
320 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
321 * (2nd condition need no check - it follows from 1st and 3rd).
322 * Else, return envvar with empty value ("optname=")
324 if (len >= (1 + 1 + 16 + 4)
326 && (option[1] + 32 - option[0]) <= 128
329 dest += sprintf(dest, "%u ", *option++);
331 dest += sprintf(dest, "%u ", *option++);
333 dest += sprint_nip6(dest, /* "", */ option);
335 len -= 1 + 1 + 16 + 4;
336 /* "+ 4" above corresponds to the length of IPv4 addr
337 * we consume in the loop below */
339 /* 6rdBRIPv4Address(es) */
340 dest += sprint_nip(dest, " ", option);
342 len -= 4; /* do we have yet another 4+ bytes? */
349 #if ENABLE_FEATURE_UDHCP_RFC3397
350 case OPTION_DNS_STRING:
351 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
352 dest = dname_dec(option, len, ret);
357 /* error. return "optname=" string */
359 case OPTION_SIP_SERVERS:
360 /* Option binary format:
362 * type=0: domain names, dns-compressed
367 if (option[-1] == 0) {
368 dest = dname_dec(option, len, ret);
374 if (option[-1] == 1) {
375 const char *pfx = "";
380 dest += sprint_nip(dest, pfx, option);
389 /* If we are here, try to format any remaining data
390 * in the option as another, similarly-formatted option
394 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
395 // Should we bail out/warn if we see multi-ip option which is
396 // not allowed to be such (for example, DHCP_BROADCAST)? -
397 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
406 /* put all the parameters into the environment */
407 static char **fill_envp(struct dhcp_packet *packet)
412 const char *opt_name;
414 uint8_t overload = 0;
416 #define BITMAP unsigned
417 #define BBITS (sizeof(BITMAP) * 8)
418 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
419 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
420 BITMAP found_opts[256 / BBITS];
422 memset(found_opts, 0, sizeof(found_opts));
424 /* We need 6 elements for:
426 * "ip=N.N.N.N" from packet->yiaddr
427 * "siaddr=IP" from packet->siaddr_nip (unless 0)
428 * "boot_file=FILE" from packet->file (unless overloaded)
429 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
433 /* +1 element for each option, +2 for subnet option: */
435 /* note: do not search for "pad" (0) and "end" (255) options */
436 //TODO: change logic to scan packet _once_
437 for (i = 1; i < 255; i++) {
438 temp = udhcp_get_option(packet, i);
440 if (i == DHCP_OPTION_OVERLOAD)
442 else if (i == DHCP_SUBNET)
443 envc++; /* for $mask */
445 /*if (i != DHCP_MESSAGE_TYPE)*/
446 FOUND_OPTS(i) |= BMASK(i);
450 curr = envp = xzalloc(sizeof(envp[0]) * envc);
452 *curr = xasprintf("interface=%s", client_config.interface);
458 /* Export BOOTP fields. Fields we don't (yet?) export:
459 * uint8_t op; // always BOOTREPLY
460 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
461 * uint8_t hlen; // hardware address length
462 * uint8_t hops; // used by relay agents only
464 * uint16_t secs; // elapsed since client began acquisition/renewal
465 * uint16_t flags; // only one flag so far: bcast. Never set by server
466 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
467 * // if during renew server wants to give us differn IP?)
468 * uint32_t gateway_nip; // relay agent IP address
469 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
470 * TODO: export gateway_nip as $giaddr?
472 /* Most important one: yiaddr as $ip */
473 *curr = xmalloc(sizeof("ip=255.255.255.255"));
474 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
476 if (packet->siaddr_nip) {
477 /* IP address of next server to use in bootstrap */
478 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
479 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
482 if (!(overload & FILE_FIELD) && packet->file[0]) {
483 /* watch out for invalid packets */
484 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
487 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
488 /* watch out for invalid packets */
489 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
493 /* Export known DHCP options */
494 opt_name = dhcp_option_strings;
497 uint8_t code = dhcp_optflags[i].code;
498 BITMAP *found_ptr = &FOUND_OPTS(code);
499 BITMAP found_mask = BMASK(code);
500 if (!(*found_ptr & found_mask))
502 *found_ptr &= ~found_mask; /* leave only unknown options */
503 temp = udhcp_get_option(packet, code);
504 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
506 if (code == DHCP_SUBNET) {
507 /* Subnet option: make things like "$ip/$mask" possible */
509 move_from_unaligned32(subnet, temp);
510 *curr = xasprintf("mask=%u", mton(subnet));
514 opt_name += strlen(opt_name) + 1;
517 /* Export unknown options */
518 for (i = 0; i < 256;) {
519 BITMAP bitmap = FOUND_OPTS(i);
524 if (bitmap & BMASK(i)) {
527 temp = udhcp_get_option(packet, i);
528 /* udhcp_get_option returns ptr to data portion,
529 * need to go back to get len
531 len = temp[-OPT_DATA + OPT_LEN];
532 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
533 ofs = sprintf(*curr, "opt%u=", i);
534 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
543 /* Call a script with a par file and env vars */
544 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
549 envp = fill_envp(packet);
552 log1("Executing %s %s", client_config.script, name);
553 argv[0] = (char*) client_config.script;
554 argv[1] = (char*) name;
556 spawn_and_wait(argv);
558 for (curr = envp; *curr; curr++) {
560 bb_unsetenv_and_free(*curr);
566 /*** Sending/receiving packets ***/
568 static ALWAYS_INLINE uint32_t random_xid(void)
573 /* Initialize the packet with the proper defaults */
574 static void init_packet(struct dhcp_packet *packet, char type)
578 /* Fill in: op, htype, hlen, cookie fields; message type option: */
579 udhcp_init_header(packet, type);
581 packet->xid = random_xid();
583 client_config.last_secs = monotonic_sec();
584 if (client_config.first_secs == 0)
585 client_config.first_secs = client_config.last_secs;
586 secs = client_config.last_secs - client_config.first_secs;
587 packet->secs = htons(secs);
589 memcpy(packet->chaddr, client_config.client_mac, 6);
590 if (client_config.clientid)
591 udhcp_add_binary_option(packet, client_config.clientid);
594 static void add_client_options(struct dhcp_packet *packet)
598 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
600 /* Add a "param req" option with the list of options we'd like to have
601 * from stubborn DHCP servers. Pull the data from the struct in common.c.
602 * No bounds checking because it goes towards the head of the packet. */
603 end = udhcp_end_option(packet->options);
605 for (i = 1; i < DHCP_END; i++) {
606 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
607 packet->options[end + OPT_DATA + len] = i;
612 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
613 packet->options[end + OPT_LEN] = len;
614 packet->options[end + OPT_DATA + len] = DHCP_END;
617 if (client_config.vendorclass)
618 udhcp_add_binary_option(packet, client_config.vendorclass);
619 if (client_config.hostname)
620 udhcp_add_binary_option(packet, client_config.hostname);
621 if (client_config.fqdn)
622 udhcp_add_binary_option(packet, client_config.fqdn);
624 /* Request broadcast replies if we have no IP addr */
625 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
626 packet->flags |= htons(BROADCAST_FLAG);
628 /* Add -x options if any */
630 struct option_set *curr = client_config.options;
632 udhcp_add_binary_option(packet, curr->data);
635 // if (client_config.sname)
636 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
637 // if (client_config.boot_file)
638 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
641 // This will be needed if we remove -V VENDOR_STR in favor of
642 // -x vendor:VENDOR_STR
643 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
644 // /* not set, set the default vendor ID */
645 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
649 * 4.4.4 Use of broadcast and unicast
651 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
652 * messages, unless the client knows the address of a DHCP server.
653 * The client unicasts DHCPRELEASE messages to the server. Because
654 * the client is declining the use of the IP address supplied by the server,
655 * the client broadcasts DHCPDECLINE messages.
657 * When the DHCP client knows the address of a DHCP server, in either
658 * INIT or REBOOTING state, the client may use that address
659 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
660 * The client may also use unicast to send DHCPINFORM messages
661 * to a known DHCP server. If the client receives no response to DHCP
662 * messages sent to the IP address of a known DHCP server, the DHCP
663 * client reverts to using the IP broadcast address.
666 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
668 return udhcp_send_raw_packet(packet,
669 /*src*/ INADDR_ANY, CLIENT_PORT,
670 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
671 client_config.ifindex);
674 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
677 return udhcp_send_kernel_packet(packet,
679 server, SERVER_PORT);
680 return raw_bcast_from_client_config_ifindex(packet);
683 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
684 /* NOINLINE: limit stack usage in caller */
685 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
687 struct dhcp_packet packet;
689 /* Fill in: op, htype, hlen, cookie, chaddr fields,
690 * random xid field (we override it below),
691 * client-id option (unless -C), message type option:
693 init_packet(&packet, DHCPDISCOVER);
697 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
699 /* Add options: maxsize,
700 * optionally: hostname, fqdn, vendorclass,
701 * "param req" option according to -O, options specified with -x
703 add_client_options(&packet);
705 bb_info_msg("Sending discover...");
706 return raw_bcast_from_client_config_ifindex(&packet);
709 /* Broadcast a DHCP request message */
710 /* RFC 2131 3.1 paragraph 3:
711 * "The client _broadcasts_ a DHCPREQUEST message..."
713 /* NOINLINE: limit stack usage in caller */
714 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
716 struct dhcp_packet packet;
720 * RFC 2131 4.3.2 DHCPREQUEST message
722 * If the DHCPREQUEST message contains a 'server identifier'
723 * option, the message is in response to a DHCPOFFER message.
724 * Otherwise, the message is a request to verify or extend an
725 * existing lease. If the client uses a 'client identifier'
726 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
727 * in all subsequent messages. If the client included a list
728 * of requested parameters in a DHCPDISCOVER message, it MUST
729 * include that list in all subsequent messages.
731 /* Fill in: op, htype, hlen, cookie, chaddr fields,
732 * random xid field (we override it below),
733 * client-id option (unless -C), message type option:
735 init_packet(&packet, DHCPREQUEST);
738 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
740 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
742 /* Add options: maxsize,
743 * optionally: hostname, fqdn, vendorclass,
744 * "param req" option according to -O, and options specified with -x
746 add_client_options(&packet);
748 addr.s_addr = requested;
749 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
750 return raw_bcast_from_client_config_ifindex(&packet);
753 /* Unicast or broadcast a DHCP renew message */
754 /* NOINLINE: limit stack usage in caller */
755 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
757 struct dhcp_packet packet;
760 * RFC 2131 4.3.2 DHCPREQUEST message
762 * DHCPREQUEST generated during RENEWING state:
764 * 'server identifier' MUST NOT be filled in, 'requested IP address'
765 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
766 * client's IP address. In this situation, the client is completely
767 * configured, and is trying to extend its lease. This message will
768 * be unicast, so no relay agents will be involved in its
769 * transmission. Because 'giaddr' is therefore not filled in, the
770 * DHCP server will trust the value in 'ciaddr', and use it when
771 * replying to the client.
773 /* Fill in: op, htype, hlen, cookie, chaddr fields,
774 * random xid field (we override it below),
775 * client-id option (unless -C), message type option:
777 init_packet(&packet, DHCPREQUEST);
780 packet.ciaddr = ciaddr;
782 /* Add options: maxsize,
783 * optionally: hostname, fqdn, vendorclass,
784 * "param req" option according to -O, and options specified with -x
786 add_client_options(&packet);
788 bb_info_msg("Sending renew...");
789 return bcast_or_ucast(&packet, ciaddr, server);
792 #if ENABLE_FEATURE_UDHCPC_ARPING
793 /* Broadcast a DHCP decline message */
794 /* NOINLINE: limit stack usage in caller */
795 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
797 struct dhcp_packet packet;
799 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
800 * client-id option (unless -C), message type option:
802 init_packet(&packet, DHCPDECLINE);
805 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
806 * but in case the server is buggy and wants DHCPDECLINE's xid
807 * to match the xid which started entire handshake,
808 * we use the same xid we used in initial DHCPDISCOVER:
812 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
813 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
815 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
817 bb_info_msg("Sending decline...");
818 return raw_bcast_from_client_config_ifindex(&packet);
822 /* Unicast a DHCP release message */
823 static int send_release(uint32_t server, uint32_t ciaddr)
825 struct dhcp_packet packet;
827 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
828 * client-id option (unless -C), message type option:
830 init_packet(&packet, DHCPRELEASE);
832 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
833 packet.ciaddr = ciaddr;
835 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
837 bb_info_msg("Sending release...");
838 /* Note: normally we unicast here since "server" is not zero.
839 * However, there _are_ people who run "address-less" DHCP servers,
840 * and reportedly ISC dhcp client and Windows allow that.
842 return bcast_or_ucast(&packet, ciaddr, server);
845 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
846 /* NOINLINE: limit stack usage in caller */
847 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
850 struct ip_udp_dhcp_packet packet;
852 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
855 struct cmsghdr *cmsg;
857 /* used to use just safe_read(fd, &packet, sizeof(packet))
858 * but we need to check for TP_STATUS_CSUMNOTREADY :(
860 iov.iov_base = &packet;
861 iov.iov_len = sizeof(packet);
862 memset(&msg, 0, sizeof(msg));
865 msg.msg_control = cmsgbuf;
866 msg.msg_controllen = sizeof(cmsgbuf);
868 bytes = recvmsg(fd, &msg, 0);
872 log1("Packet read error, ignoring");
873 /* NB: possible down interface, etc. Caller should pause. */
874 return bytes; /* returns -1 */
879 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
880 log1("Packet is too short, ignoring");
884 if (bytes < ntohs(packet.ip.tot_len)) {
885 /* packet is bigger than sizeof(packet), we did partial read */
886 log1("Oversized packet, ignoring");
890 /* ignore any extra garbage bytes */
891 bytes = ntohs(packet.ip.tot_len);
893 /* make sure its the right packet for us, and that it passes sanity checks */
894 if (packet.ip.protocol != IPPROTO_UDP
895 || packet.ip.version != IPVERSION
896 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
897 || packet.udp.dest != htons(CLIENT_PORT)
898 /* || bytes > (int) sizeof(packet) - can't happen */
899 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
901 log1("Unrelated/bogus packet, ignoring");
905 /* verify IP checksum */
906 check = packet.ip.check;
908 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
909 log1("Bad IP header checksum, ignoring");
913 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
914 if (cmsg->cmsg_level == SOL_PACKET
915 && cmsg->cmsg_type == PACKET_AUXDATA
917 /* some VMs don't checksum UDP and TCP data
918 * they send to the same physical machine,
919 * here we detect this case:
921 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
922 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
923 goto skip_udp_sum_check;
927 /* verify UDP checksum. IP header has to be modified for this */
928 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
929 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
930 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
931 check = packet.udp.check;
932 packet.udp.check = 0;
933 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
934 log1("Packet with bad UDP checksum received, ignoring");
939 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
940 bb_info_msg("Packet with bad magic, ignoring");
944 log1("Received a packet");
945 udhcp_dump_packet(&packet.data);
947 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
948 memcpy(dhcp_pkt, &packet.data, bytes);
955 static int sockfd = -1;
957 #define LISTEN_NONE 0
958 #define LISTEN_KERNEL 1
960 static smallint listen_mode;
962 /* initial state: (re)start DHCP negotiation */
963 #define INIT_SELECTING 0
964 /* discover was sent, DHCPOFFER reply received */
966 /* select/renew was sent, DHCPACK reply received */
968 /* half of lease passed, want to renew it by sending unicast renew requests */
970 /* renew requests were not answered, lease is almost over, send broadcast renew */
972 /* manually requested renew (SIGUSR1) */
973 #define RENEW_REQUESTED 5
974 /* release, possibly manually requested (SIGUSR2) */
976 static smallint state;
978 static int udhcp_raw_socket(int ifindex)
981 struct sockaddr_ll sock;
983 log1("Opening raw socket on ifindex %d", ifindex); //log2?
985 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
987 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
988 * ETH_P_IP: want to receive only packets with IPv4 eth type
990 log1("Got raw socket fd"); //log2?
992 sock.sll_family = AF_PACKET;
993 sock.sll_protocol = htons(ETH_P_IP);
994 sock.sll_ifindex = ifindex;
995 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
997 #if 0 /* Several users reported breakage when BPF filter is used */
998 if (CLIENT_PORT == 68) {
999 /* Use only if standard port is in use */
1001 * I've selected not to see LL header, so BPF doesn't see it, too.
1002 * The filter may also pass non-IP and non-ARP packets, but we do
1003 * a more complete check when receiving the message in userspace.
1005 * and filter shamelessly stolen from:
1007 * http://www.flamewarmaster.de/software/dhcpclient/
1009 * There are a few other interesting ideas on that page (look under
1010 * "Motivation"). Use of netlink events is most interesting. Think
1011 * of various network servers listening for events and reconfiguring.
1012 * That would obsolete sending HUP signals and/or make use of restarts.
1014 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1017 static const struct sock_filter filter_instr[] = {
1018 /* load 9th byte (protocol) */
1019 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1020 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1021 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1022 /* L1: load halfword from offset 6 (flags and frag offset) */
1023 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1024 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1025 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1026 /* L2: skip IP header (load index reg with header len) */
1027 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1028 /* load udp destination port from halfword[header_len + 2] */
1029 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1030 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1031 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1032 /* L3: accept packet ("accept 0x7fffffff bytes") */
1033 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1034 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1035 /* L4: discard packet ("accept zero bytes") */
1036 BPF_STMT(BPF_RET|BPF_K, 0),
1038 static const struct sock_fprog filter_prog = {
1039 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1040 /* casting const away: */
1041 .filter = (struct sock_filter *) filter_instr,
1043 /* Ignoring error (kernel may lack support for this) */
1044 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1045 sizeof(filter_prog)) >= 0)
1046 log1("Attached filter to raw socket fd"); // log?
1050 if (setsockopt(fd, SOL_PACKET, PACKET_AUXDATA,
1051 &const_int_1, sizeof(int)) < 0
1053 if (errno != ENOPROTOOPT)
1054 log1("Can't set PACKET_AUXDATA on raw socket");
1057 log1("Created raw socket");
1062 static void change_listen_mode(int new_mode)
1064 log1("Entering listen mode: %s",
1065 new_mode != LISTEN_NONE
1066 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1070 listen_mode = new_mode;
1075 if (new_mode == LISTEN_KERNEL)
1076 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1077 else if (new_mode != LISTEN_NONE)
1078 sockfd = udhcp_raw_socket(client_config.ifindex);
1079 /* else LISTEN_NONE: sockfd stays closed */
1082 /* Called only on SIGUSR1 */
1083 static void perform_renew(void)
1085 bb_info_msg("Performing a DHCP renew");
1088 change_listen_mode(LISTEN_KERNEL);
1091 state = RENEW_REQUESTED;
1093 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1094 udhcp_run_script(NULL, "deconfig");
1097 change_listen_mode(LISTEN_RAW);
1098 state = INIT_SELECTING;
1100 case INIT_SELECTING:
1105 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1107 char buffer[sizeof("255.255.255.255")];
1108 struct in_addr temp_addr;
1110 /* send release packet */
1111 if (state == BOUND || state == RENEWING || state == REBINDING) {
1112 temp_addr.s_addr = server_addr;
1113 strcpy(buffer, inet_ntoa(temp_addr));
1114 temp_addr.s_addr = requested_ip;
1115 bb_info_msg("Unicasting a release of %s to %s",
1116 inet_ntoa(temp_addr), buffer);
1117 send_release(server_addr, requested_ip); /* unicast */
1118 udhcp_run_script(NULL, "deconfig");
1120 bb_info_msg("Entering released state");
1122 change_listen_mode(LISTEN_NONE);
1126 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1129 int len = strnlen(str, 255);
1130 storage = xzalloc(len + extra + OPT_DATA);
1131 storage[OPT_CODE] = code;
1132 storage[OPT_LEN] = len + extra;
1133 memcpy(storage + extra + OPT_DATA, str, len);
1138 static void client_background(void)
1141 logmode &= ~LOGMODE_STDIO;
1142 /* rewrite pidfile, as our pid is different now */
1143 write_pidfile(client_config.pidfile);
1147 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1148 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1150 //usage:# define IF_UDHCP_VERBOSE(...)
1152 //usage:#define udhcpc_trivial_usage
1153 //usage: "[-fbq"IF_UDHCP_VERBOSE("v")IF_FEATURE_UDHCPC_ARPING("a")"RB] [-t N] [-T SEC] [-A SEC/-n]\n"
1154 //usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1155 //usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1156 //usage:#define udhcpc_full_usage "\n"
1157 //usage: IF_LONG_OPTS(
1158 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1159 //usage: IF_FEATURE_UDHCP_PORT(
1160 //usage: "\n -P,--client-port PORT Use PORT (default 68)"
1162 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1163 //usage: "\n -p,--pidfile FILE Create pidfile"
1164 //usage: "\n -B,--broadcast Request broadcast replies"
1165 //usage: "\n -t,--retries N Send up to N discover packets (default 3)"
1166 //usage: "\n -T,--timeout SEC Pause between packets (default 3)"
1167 //usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
1168 //usage: "\n -n,--now Exit if lease is not obtained"
1169 //usage: "\n -q,--quit Exit after obtaining lease"
1170 //usage: "\n -R,--release Release IP on exit"
1171 //usage: "\n -f,--foreground Run in foreground"
1172 //usage: USE_FOR_MMU(
1173 //usage: "\n -b,--background Background if lease is not obtained"
1175 //usage: "\n -S,--syslog Log to syslog too"
1176 //usage: IF_FEATURE_UDHCPC_ARPING(
1177 //usage: "\n -a,--arping Use arping to validate offered address"
1179 //usage: "\n -r,--request IP Request this IP address"
1180 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1181 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1182 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1183 //usage: "\n Examples of string, numeric, and hex byte opts:"
1184 //usage: "\n -x hostname:bbox - option 12"
1185 //usage: "\n -x lease:3600 - option 51 (lease time)"
1186 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1187 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1188 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1189 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1190 //usage: IF_UDHCP_VERBOSE(
1191 //usage: "\n -v Verbose"
1194 //usage: IF_NOT_LONG_OPTS(
1195 //usage: "\n -i IFACE Interface to use (default eth0)"
1196 //usage: IF_FEATURE_UDHCP_PORT(
1197 //usage: "\n -P PORT Use PORT (default 68)"
1199 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1200 //usage: "\n -p FILE Create pidfile"
1201 //usage: "\n -B Request broadcast replies"
1202 //usage: "\n -t N Send up to N discover packets (default 3)"
1203 //usage: "\n -T SEC Pause between packets (default 3)"
1204 //usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1205 //usage: "\n -n Exit if lease is not obtained"
1206 //usage: "\n -q Exit after obtaining lease"
1207 //usage: "\n -R Release IP on exit"
1208 //usage: "\n -f Run in foreground"
1209 //usage: USE_FOR_MMU(
1210 //usage: "\n -b Background if lease is not obtained"
1212 //usage: "\n -S Log to syslog too"
1213 //usage: IF_FEATURE_UDHCPC_ARPING(
1214 //usage: "\n -a Use arping to validate offered address"
1216 //usage: "\n -r IP Request this IP address"
1217 //usage: "\n -o Don't request any options (unless -O is given)"
1218 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1219 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1220 //usage: "\n Examples of string, numeric, and hex byte opts:"
1221 //usage: "\n -x hostname:bbox - option 12"
1222 //usage: "\n -x lease:3600 - option 51 (lease time)"
1223 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1224 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1225 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1226 //usage: "\n -C Don't send MAC as client identifier"
1227 //usage: IF_UDHCP_VERBOSE(
1228 //usage: "\n -v Verbose"
1231 //usage: "\nSignals:"
1232 //usage: "\n USR1 Renew lease"
1233 //usage: "\n USR2 Release lease"
1236 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1237 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1240 const char *str_V, *str_h, *str_F, *str_r;
1241 IF_FEATURE_UDHCP_PORT(char *str_P;)
1242 void *clientid_mac_ptr;
1243 llist_t *list_O = NULL;
1244 llist_t *list_x = NULL;
1245 int tryagain_timeout = 20;
1246 int discover_timeout = 3;
1247 int discover_retries = 3;
1248 uint32_t server_addr = server_addr; /* for compiler */
1249 uint32_t requested_ip = 0;
1250 uint32_t xid = xid; /* for compiler */
1252 int timeout; /* must be signed */
1253 unsigned already_waited_sec;
1259 /* Default options */
1260 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1261 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1262 client_config.interface = "eth0";
1263 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1264 str_V = "udhcp "BB_VER;
1266 /* Parse command line */
1267 /* O,x: list; -T,-t,-A take numeric param */
1268 opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1269 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1270 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1272 IF_FEATURE_UDHCPC_ARPING("a")
1273 IF_FEATURE_UDHCP_PORT("P:")
1275 , &str_V, &str_h, &str_h, &str_F
1276 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1277 , &client_config.script /* s */
1278 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1281 IF_FEATURE_UDHCP_PORT(, &str_P)
1282 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1284 if (opt & (OPT_h|OPT_H)) {
1286 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1287 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1290 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1291 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1292 /* Flag bits: 0000NEOS
1293 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1294 * O: 1 = Server indicates to client that DNS has been updated regardless
1295 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1296 * not "host.domain.com". Format 0 is obsolete.
1297 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1298 * Two [0] bytes which follow are deprecated and must be 0.
1300 client_config.fqdn[OPT_DATA + 0] = 0x1;
1301 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1302 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1305 requested_ip = inet_addr(str_r);
1306 #if ENABLE_FEATURE_UDHCP_PORT
1308 CLIENT_PORT = xatou16(str_P);
1309 SERVER_PORT = CLIENT_PORT - 1;
1313 char *optstr = llist_pop(&list_O);
1314 unsigned n = bb_strtou(optstr, NULL, 0);
1315 if (errno || n > 254) {
1316 n = udhcp_option_idx(optstr);
1317 n = dhcp_optflags[n].code;
1319 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1321 if (!(opt & OPT_o)) {
1323 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1324 if (dhcp_optflags[i].flags & OPTION_REQ) {
1325 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1330 char *optstr = llist_pop(&list_x);
1331 char *colon = strchr(optstr, ':');
1334 /* now it looks similar to udhcpd's config file line:
1335 * "optname optval", using the common routine: */
1336 udhcp_str2optset(optstr, &client_config.options);
1339 if (udhcp_read_interface(client_config.interface,
1340 &client_config.ifindex,
1342 client_config.client_mac)
1347 clientid_mac_ptr = NULL;
1348 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1349 /* not suppressed and not set, set the default client ID */
1350 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1351 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1352 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1353 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1355 if (str_V[0] != '\0') {
1356 // can drop -V, str_V, client_config.vendorclass,
1357 // but need to add "vendor" to the list of recognized
1358 // string opts for this to work;
1359 // and need to tweak add_client_options() too...
1360 // ...so the question is, should we?
1361 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1362 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1366 /* on NOMMU reexec (i.e., background) early */
1367 if (!(opt & OPT_f)) {
1368 bb_daemonize_or_rexec(0 /* flags */, argv);
1369 logmode = LOGMODE_NONE;
1373 openlog(applet_name, LOG_PID, LOG_DAEMON);
1374 logmode |= LOGMODE_SYSLOG;
1377 /* Make sure fd 0,1,2 are open */
1378 bb_sanitize_stdio();
1379 /* Equivalent of doing a fflush after every \n */
1381 /* Create pidfile */
1382 write_pidfile(client_config.pidfile);
1383 /* Goes to stdout (unless NOMMU) and possibly syslog */
1384 bb_info_msg("%s (v"BB_VER") started", applet_name);
1385 /* Set up the signal pipe */
1387 /* We want random_xid to be random... */
1388 srand(monotonic_us());
1390 state = INIT_SELECTING;
1391 udhcp_run_script(NULL, "deconfig");
1392 change_listen_mode(LISTEN_RAW);
1395 already_waited_sec = 0;
1397 /* Main event loop. select() waits on signal pipe and possibly
1399 * "continue" statements in code below jump to the top of the loop.
1403 struct dhcp_packet packet;
1404 /* silence "uninitialized!" warning */
1405 unsigned timestamp_before_wait = timestamp_before_wait;
1407 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1409 /* Was opening raw or udp socket here
1410 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1411 * but on fast network renew responses return faster
1412 * than we open sockets. Thus this code is moved
1413 * to change_listen_mode(). Thus we open listen socket
1414 * BEFORE we send renew request (see "case BOUND:"). */
1416 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1418 tv.tv_sec = timeout - already_waited_sec;
1421 /* If we already timed out, fall through with retval = 0, else... */
1422 if ((int)tv.tv_sec > 0) {
1423 log1("Waiting on select %u seconds", (int)tv.tv_sec);
1424 timestamp_before_wait = (unsigned)monotonic_sec();
1425 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1427 /* EINTR? A signal was caught, don't panic */
1428 if (errno == EINTR) {
1429 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1432 /* Else: an error occured, panic! */
1433 bb_perror_msg_and_die("select");
1437 /* If timeout dropped to zero, time to become active:
1438 * resend discover/renew/whatever
1441 /* When running on a bridge, the ifindex may have changed
1442 * (e.g. if member interfaces were added/removed
1443 * or if the status of the bridge changed).
1444 * Refresh ifindex and client_mac:
1446 if (udhcp_read_interface(client_config.interface,
1447 &client_config.ifindex,
1449 client_config.client_mac)
1451 goto ret0; /* iface is gone? */
1453 if (clientid_mac_ptr)
1454 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1456 /* We will restart the wait in any case */
1457 already_waited_sec = 0;
1460 case INIT_SELECTING:
1461 if (!discover_retries || packet_num < discover_retries) {
1462 if (packet_num == 0)
1465 send_discover(xid, requested_ip);
1466 timeout = discover_timeout;
1471 udhcp_run_script(NULL, "leasefail");
1472 #if BB_MMU /* -b is not supported on NOMMU */
1473 if (opt & OPT_b) { /* background if no lease */
1474 bb_info_msg("No lease, forking to background");
1475 client_background();
1476 /* do not background again! */
1477 opt = ((opt & ~OPT_b) | OPT_f);
1480 if (opt & OPT_n) { /* abort if no lease */
1481 bb_info_msg("No lease, failing");
1485 /* wait before trying again */
1486 timeout = tryagain_timeout;
1490 if (!discover_retries || packet_num < discover_retries) {
1491 /* send broadcast select packet */
1492 send_select(xid, server_addr, requested_ip);
1493 timeout = discover_timeout;
1497 /* Timed out, go back to init state.
1498 * "discover...select...discover..." loops
1499 * were seen in the wild. Treat them similarly
1500 * to "no response to discover" case */
1501 change_listen_mode(LISTEN_RAW);
1502 state = INIT_SELECTING;
1505 /* 1/2 lease passed, enter renewing state */
1507 client_config.first_secs = 0; /* make secs field count from 0 */
1508 change_listen_mode(LISTEN_KERNEL);
1509 log1("Entering renew state");
1510 /* fall right through */
1511 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1512 case_RENEW_REQUESTED:
1515 /* send an unicast renew request */
1516 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1517 * a new UDP socket for sending inside send_renew.
1518 * I hazard to guess existing listening socket
1519 * is somehow conflicting with it, but why is it
1520 * not deterministic then?! Strange.
1521 * Anyway, it does recover by eventually failing through
1522 * into INIT_SELECTING state.
1524 send_renew(xid, server_addr, requested_ip);
1528 /* Timed out, enter rebinding state */
1529 log1("Entering rebinding state");
1531 /* fall right through */
1533 /* Switch to bcast receive */
1534 change_listen_mode(LISTEN_RAW);
1535 /* Lease is *really* about to run out,
1536 * try to find DHCP server using broadcast */
1538 /* send a broadcast renew request */
1539 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1543 /* Timed out, enter init state */
1544 bb_info_msg("Lease lost, entering init state");
1545 udhcp_run_script(NULL, "deconfig");
1546 state = INIT_SELECTING;
1547 client_config.first_secs = 0; /* make secs field count from 0 */
1548 /*timeout = 0; - already is */
1551 /* case RELEASED: */
1553 /* yah, I know, *you* say it would never happen */
1555 continue; /* back to main loop */
1556 } /* if select timed out */
1558 /* select() didn't timeout, something happened */
1560 /* Is it a signal? */
1561 /* note: udhcp_sp_read checks FD_ISSET before reading */
1562 switch (udhcp_sp_read(&rfds)) {
1564 client_config.first_secs = 0; /* make secs field count from 0 */
1565 already_waited_sec = 0;
1567 if (state == RENEW_REQUESTED) {
1568 /* We might be either on the same network
1569 * (in which case renew might work),
1570 * or we might be on a completely different one
1571 * (in which case renew won't ever succeed).
1572 * For the second case, must make sure timeout
1573 * is not too big, or else we can send
1574 * futile renew requests for hours.
1575 * (Ab)use -A TIMEOUT value (usually 20 sec)
1576 * as a cap on the timeout.
1578 if (timeout > tryagain_timeout)
1579 timeout = tryagain_timeout;
1580 goto case_RENEW_REQUESTED;
1582 /* Start things over */
1584 /* Kill any timeouts, user wants this to hurry along */
1588 perform_release(server_addr, requested_ip);
1592 bb_info_msg("Received SIGTERM");
1596 /* Is it a packet? */
1597 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1603 /* A packet is ready, read it */
1604 if (listen_mode == LISTEN_KERNEL)
1605 len = udhcp_recv_kernel_packet(&packet, sockfd);
1607 len = udhcp_recv_raw_packet(&packet, sockfd);
1609 /* Error is severe, reopen socket */
1610 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1611 sleep(discover_timeout); /* 3 seconds by default */
1612 change_listen_mode(listen_mode); /* just close and reopen */
1614 /* If this packet will turn out to be unrelated/bogus,
1615 * we will go back and wait for next one.
1616 * Be sure timeout is properly decreased. */
1617 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1622 if (packet.xid != xid) {
1623 log1("xid %x (our is %x), ignoring packet",
1624 (unsigned)packet.xid, (unsigned)xid);
1628 /* Ignore packets that aren't for us */
1629 if (packet.hlen != 6
1630 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1632 //FIXME: need to also check that last 10 bytes are zero
1633 log1("chaddr does not match, ignoring packet"); // log2?
1637 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1638 if (message == NULL) {
1639 bb_error_msg("no message type option, ignoring packet");
1644 case INIT_SELECTING:
1645 /* Must be a DHCPOFFER */
1646 if (*message == DHCPOFFER) {
1649 /* What exactly is server's IP? There are several values.
1650 * Example DHCP offer captured with tchdump:
1652 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1654 * Your-IP 10.34.25.202
1655 * Server-IP 10.34.32.125 // "next server" IP
1656 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1658 * DHCP-Message Option 53, length 1: Offer
1659 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1660 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1662 * We think that real server IP (one to use in renew/release)
1663 * is one in Server-ID option. But I am not 100% sure.
1664 * IP header's src and Gateway-IP (same in this example)
1666 * "Next server" and router are definitely wrong ones to use, though...
1668 /* We used to ignore pcakets without DHCP_SERVER_ID.
1669 * I've got user reports from people who run "address-less" servers.
1670 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1671 * They say ISC DHCP client supports this case.
1674 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1676 bb_error_msg("no server ID, using 0.0.0.0");
1678 /* it IS unaligned sometimes, don't "optimize" */
1679 move_from_unaligned32(server_addr, temp);
1681 /*xid = packet.xid; - already is */
1682 requested_ip = packet.yiaddr;
1684 /* enter requesting state */
1688 already_waited_sec = 0;
1693 case RENEW_REQUESTED:
1695 if (*message == DHCPACK) {
1696 uint32_t lease_seconds;
1697 struct in_addr temp_addr;
1700 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1702 bb_error_msg("no lease time with ACK, using 1 hour lease");
1703 lease_seconds = 60 * 60;
1705 /* it IS unaligned sometimes, don't "optimize" */
1706 move_from_unaligned32(lease_seconds, temp);
1707 lease_seconds = ntohl(lease_seconds);
1708 /* paranoia: must not be too small and not prone to overflows */
1709 if (lease_seconds < 0x10)
1710 lease_seconds = 0x10;
1711 if (lease_seconds >= 0x10000000)
1712 lease_seconds = 0x0fffffff;
1714 #if ENABLE_FEATURE_UDHCPC_ARPING
1716 /* RFC 2131 3.1 paragraph 5:
1717 * "The client receives the DHCPACK message with configuration
1718 * parameters. The client SHOULD perform a final check on the
1719 * parameters (e.g., ARP for allocated network address), and notes
1720 * the duration of the lease specified in the DHCPACK message. At this
1721 * point, the client is configured. If the client detects that the
1722 * address is already in use (e.g., through the use of ARP),
1723 * the client MUST send a DHCPDECLINE message to the server and restarts
1724 * the configuration process..." */
1725 if (!arpping(packet.yiaddr,
1728 client_config.client_mac,
1729 client_config.interface)
1731 bb_info_msg("Offered address is in use "
1732 "(got ARP reply), declining");
1733 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1735 if (state != REQUESTING)
1736 udhcp_run_script(NULL, "deconfig");
1737 change_listen_mode(LISTEN_RAW);
1738 state = INIT_SELECTING;
1739 client_config.first_secs = 0; /* make secs field count from 0 */
1741 timeout = tryagain_timeout;
1743 already_waited_sec = 0;
1744 continue; /* back to main loop */
1748 /* enter bound state */
1749 timeout = lease_seconds / 2;
1750 temp_addr.s_addr = packet.yiaddr;
1751 bb_info_msg("Lease of %s obtained, lease time %u",
1752 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1753 requested_ip = packet.yiaddr;
1754 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1757 change_listen_mode(LISTEN_NONE);
1758 if (opt & OPT_q) { /* quit after lease */
1761 /* future renew failures should not exit (JM) */
1763 #if BB_MMU /* NOMMU case backgrounded earlier */
1764 if (!(opt & OPT_f)) {
1765 client_background();
1766 /* do not background again! */
1767 opt = ((opt & ~OPT_b) | OPT_f);
1770 /* make future renew packets use different xid */
1771 /* xid = random_xid(); ...but why bother? */
1772 already_waited_sec = 0;
1773 continue; /* back to main loop */
1775 if (*message == DHCPNAK) {
1776 /* If network has more than one DHCP server,
1777 * "wrong" server can reply first, with a NAK.
1778 * Do not interpret it as a NAK from "our" server.
1780 if (server_addr != 0) {
1784 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1787 log1("%s with wrong server ID, ignoring packet",
1792 move_from_unaligned32(svid, temp);
1793 if (svid != server_addr)
1794 goto non_matching_svid;
1796 /* return to init state */
1797 bb_info_msg("Received DHCP NAK");
1798 udhcp_run_script(&packet, "nak");
1799 if (state != REQUESTING)
1800 udhcp_run_script(NULL, "deconfig");
1801 change_listen_mode(LISTEN_RAW);
1802 sleep(3); /* avoid excessive network traffic */
1803 state = INIT_SELECTING;
1804 client_config.first_secs = 0; /* make secs field count from 0 */
1808 already_waited_sec = 0;
1811 /* case BOUND: - ignore all packets */
1812 /* case RELEASED: - ignore all packets */
1814 /* back to main loop */
1815 } /* for (;;) - main loop ends */
1818 if (opt & OPT_R) /* release on quit */
1819 perform_release(server_addr, requested_ip);
1822 /*if (client_config.pidfile) - remove_pidfile has its own check */
1823 remove_pidfile(client_config.pidfile);