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.
21 //applet:IF_UDHCPC(APPLET(udhcpc, BB_DIR_SBIN, BB_SUID_DROP))
23 //kbuild:lib-$(CONFIG_UDHCPC) += common.o packet.o signalpipe.o socket.o
24 //kbuild:lib-$(CONFIG_UDHCPC) += dhcpc.o
25 //kbuild:lib-$(CONFIG_FEATURE_UDHCPC_ARPING) += arpping.o
26 //kbuild:lib-$(CONFIG_FEATURE_UDHCP_RFC3397) += domain_codec.o
29 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
30 #define WANT_PIDFILE 1
35 #include <netinet/if_ether.h>
36 #include <linux/filter.h>
37 #include <linux/if_packet.h>
39 #ifndef PACKET_AUXDATA
40 # define PACKET_AUXDATA 8
41 struct tpacket_auxdata {
53 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
57 static const char udhcpc_longopts[] ALIGN1 =
58 "clientid-none\0" No_argument "C"
59 "vendorclass\0" Required_argument "V"
60 "hostname\0" Required_argument "H"
61 "fqdn\0" Required_argument "F"
62 "interface\0" Required_argument "i"
63 "now\0" No_argument "n"
64 "pidfile\0" Required_argument "p"
65 "quit\0" No_argument "q"
66 "release\0" No_argument "R"
67 "request\0" Required_argument "r"
68 "script\0" Required_argument "s"
69 "timeout\0" Required_argument "T"
70 "retries\0" Required_argument "t"
71 "tryagain\0" Required_argument "A"
72 "syslog\0" No_argument "S"
73 "request-option\0" Required_argument "O"
74 "no-default-options\0" No_argument "o"
75 "foreground\0" No_argument "f"
77 "background\0" No_argument "b"
79 "broadcast\0" No_argument "B"
80 IF_FEATURE_UDHCPC_ARPING("arping\0" Optional_argument "a")
81 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
84 /* Must match getopt32 option string order */
107 /* The rest has variable bit positions, need to be clever */
109 USE_FOR_MMU( OPTBIT_b,)
110 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
111 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
112 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
113 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
114 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
118 /*** Script execution code ***/
120 /* get a rough idea of how long an option will be (rounding up...) */
121 static const uint8_t len_of_option_as_string[] ALIGN1 = {
122 [OPTION_IP ] = sizeof("255.255.255.255 "),
123 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
124 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
125 [OPTION_6RD ] = sizeof("132 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
126 [OPTION_STRING ] = 1,
127 [OPTION_STRING_HOST ] = 1,
128 #if ENABLE_FEATURE_UDHCP_RFC3397
129 [OPTION_DNS_STRING ] = 1, /* unused */
130 /* Hmmm, this severely overestimates size if SIP_SERVERS option
131 * is in domain name form: N-byte option in binary form
132 * mallocs ~16*N bytes. But it is freed almost at once.
134 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
136 // [OPTION_BOOLEAN ] = sizeof("yes "),
137 [OPTION_U8 ] = sizeof("255 "),
138 [OPTION_U16 ] = sizeof("65535 "),
139 // [OPTION_S16 ] = sizeof("-32768 "),
140 [OPTION_U32 ] = sizeof("4294967295 "),
141 [OPTION_S32 ] = sizeof("-2147483684 "),
144 /* note: ip is a pointer to an IP in network order, possibly misaliged */
145 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
147 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
150 /* really simple implementation, just count the bits */
151 static int mton(uint32_t mask)
154 mask = ntohl(mask); /* 111110000-like bit pattern */
162 #if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
163 /* Check if a given label represents a valid DNS label
164 * Return pointer to the first character after the label upon success,
168 /* We don't need to be particularly anal. For example, allowing _, hyphen
169 * at the end, or leading and trailing dots would be ok, since it
170 * can't be used for attacks. (Leading hyphen can be, if someone uses
172 * in the script: then hostname may be treated as an option)
174 static const char *valid_domain_label(const char *label)
181 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
182 if (ch < '0' || ch > '9') {
183 if (ch == '\0' || ch == '.')
185 /* DNS allows only '-', but we are more permissive */
186 if (ch != '-' && ch != '_')
193 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
198 /* Check if a given name represents a valid DNS name */
199 /* See RFC1035, 2.3.1 */
200 static int good_hostname(const char *name)
202 //const char *start = name;
205 name = valid_domain_label(name);
211 //return ((name - start) < 1025); /* NS_MAXDNAME */
214 return 1; // We allow trailing dot too
218 # define good_hostname(name) 1
221 /* Create "opt_name=opt_value" string */
222 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
224 unsigned upper_length;
225 int len, type, optlen;
228 /* option points to OPT_DATA, need to go back to get OPT_LEN */
229 len = option[-OPT_DATA + OPT_LEN];
231 type = optflag->flags & OPTION_TYPE_MASK;
232 optlen = dhcp_option_lengths[type];
233 upper_length = len_of_option_as_string[type]
234 * ((unsigned)(len + optlen) / (unsigned)optlen);
236 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
237 dest += sprintf(ret, "%s=", opt_name);
239 while (len >= optlen) {
243 dest += sprint_nip(dest, "", option);
244 if (type == OPTION_IP)
246 dest += sprint_nip(dest, "/", option + 4);
248 // case OPTION_BOOLEAN:
249 // dest += sprintf(dest, *option ? "yes" : "no");
252 dest += sprintf(dest, "%u", *option);
257 move_from_unaligned16(val_u16, option);
258 dest += sprintf(dest, "%u", ntohs(val_u16));
264 move_from_unaligned32(val_u32, option);
265 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
268 /* Note: options which use 'return' instead of 'break'
269 * (for example, OPTION_STRING) skip the code which handles
270 * the case of list of options.
273 case OPTION_STRING_HOST:
274 memcpy(dest, option, len);
276 if (type == OPTION_STRING_HOST && !good_hostname(dest))
277 safe_strncpy(dest, "bad", len);
279 case OPTION_STATIC_ROUTES: {
280 /* Option binary format:
281 * mask [one byte, 0..32]
282 * ip [big endian, 0..4 bytes depending on mask]
283 * router [big endian, 4 bytes]
286 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
288 const char *pfx = "";
290 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
303 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
304 while (--bytes >= 0) {
312 dest += sprint_nip(dest, pfx, (void*) &nip);
314 dest += sprintf(dest, "/%u ", mask);
316 dest += sprint_nip(dest, "", option);
324 /* Option binary format (see RFC 5969):
326 * 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
327 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
328 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
329 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
331 * ... (16 octets) ...
332 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
333 * ... 6rdBRIPv4Address(es) ...
334 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
335 * We convert it to a string
336 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
338 * Sanity check: ensure that our length is at least 22 bytes, that
340 * 6rdPrefixLen <= 128,
341 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
342 * (2nd condition need no check - it follows from 1st and 3rd).
343 * Else, return envvar with empty value ("optname=")
345 if (len >= (1 + 1 + 16 + 4)
347 && (option[1] + 32 - option[0]) <= 128
350 dest += sprintf(dest, "%u ", *option++);
352 dest += sprintf(dest, "%u ", *option++);
354 dest += sprint_nip6(dest, /* "", */ option);
356 len -= 1 + 1 + 16 + 4;
357 /* "+ 4" above corresponds to the length of IPv4 addr
358 * we consume in the loop below */
360 /* 6rdBRIPv4Address(es) */
361 dest += sprint_nip(dest, " ", option);
363 len -= 4; /* do we have yet another 4+ bytes? */
370 #if ENABLE_FEATURE_UDHCP_RFC3397
371 case OPTION_DNS_STRING:
372 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
373 dest = dname_dec(option, len, ret);
378 /* error. return "optname=" string */
380 case OPTION_SIP_SERVERS:
381 /* Option binary format:
383 * type=0: domain names, dns-compressed
388 if (option[-1] == 0) {
389 dest = dname_dec(option, len, ret);
395 if (option[-1] == 1) {
396 const char *pfx = "";
401 dest += sprint_nip(dest, pfx, option);
410 /* If we are here, try to format any remaining data
411 * in the option as another, similarly-formatted option
415 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
416 // Should we bail out/warn if we see multi-ip option which is
417 // not allowed to be such (for example, DHCP_BROADCAST)? -
418 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
427 /* put all the parameters into the environment */
428 static char **fill_envp(struct dhcp_packet *packet)
433 const char *opt_name;
435 uint8_t overload = 0;
437 #define BITMAP unsigned
438 #define BBITS (sizeof(BITMAP) * 8)
439 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
440 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
441 BITMAP found_opts[256 / BBITS];
443 memset(found_opts, 0, sizeof(found_opts));
445 /* We need 6 elements for:
447 * "ip=N.N.N.N" from packet->yiaddr
448 * "siaddr=IP" from packet->siaddr_nip (unless 0)
449 * "boot_file=FILE" from packet->file (unless overloaded)
450 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
454 /* +1 element for each option, +2 for subnet option: */
456 /* note: do not search for "pad" (0) and "end" (255) options */
457 //TODO: change logic to scan packet _once_
458 for (i = 1; i < 255; i++) {
459 temp = udhcp_get_option(packet, i);
461 if (i == DHCP_OPTION_OVERLOAD)
463 else if (i == DHCP_SUBNET)
464 envc++; /* for $mask */
466 /*if (i != DHCP_MESSAGE_TYPE)*/
467 FOUND_OPTS(i) |= BMASK(i);
471 curr = envp = xzalloc(sizeof(envp[0]) * envc);
473 *curr = xasprintf("interface=%s", client_config.interface);
479 /* Export BOOTP fields. Fields we don't (yet?) export:
480 * uint8_t op; // always BOOTREPLY
481 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
482 * uint8_t hlen; // hardware address length
483 * uint8_t hops; // used by relay agents only
485 * uint16_t secs; // elapsed since client began acquisition/renewal
486 * uint16_t flags; // only one flag so far: bcast. Never set by server
487 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
488 * // if during renew server wants to give us different IP?)
489 * uint32_t gateway_nip; // relay agent IP address
490 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
491 * TODO: export gateway_nip as $giaddr?
493 /* Most important one: yiaddr as $ip */
494 *curr = xmalloc(sizeof("ip=255.255.255.255"));
495 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
497 if (packet->siaddr_nip) {
498 /* IP address of next server to use in bootstrap */
499 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
500 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
503 if (!(overload & FILE_FIELD) && packet->file[0]) {
504 /* watch out for invalid packets */
505 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
508 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
509 /* watch out for invalid packets */
510 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
514 /* Export known DHCP options */
515 opt_name = dhcp_option_strings;
518 uint8_t code = dhcp_optflags[i].code;
519 BITMAP *found_ptr = &FOUND_OPTS(code);
520 BITMAP found_mask = BMASK(code);
521 if (!(*found_ptr & found_mask))
523 *found_ptr &= ~found_mask; /* leave only unknown options */
524 temp = udhcp_get_option(packet, code);
525 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
527 if (code == DHCP_SUBNET) {
528 /* Subnet option: make things like "$ip/$mask" possible */
530 move_from_unaligned32(subnet, temp);
531 *curr = xasprintf("mask=%u", mton(subnet));
535 opt_name += strlen(opt_name) + 1;
538 /* Export unknown options */
539 for (i = 0; i < 256;) {
540 BITMAP bitmap = FOUND_OPTS(i);
545 if (bitmap & BMASK(i)) {
548 temp = udhcp_get_option(packet, i);
549 /* udhcp_get_option returns ptr to data portion,
550 * need to go back to get len
552 len = temp[-OPT_DATA + OPT_LEN];
553 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
554 ofs = sprintf(*curr, "opt%u=", i);
555 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
564 /* Call a script with a par file and env vars */
565 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
570 envp = fill_envp(packet);
573 log1("executing %s %s", client_config.script, name);
574 argv[0] = (char*) client_config.script;
575 argv[1] = (char*) name;
577 spawn_and_wait(argv);
579 for (curr = envp; *curr; curr++) {
581 bb_unsetenv_and_free(*curr);
587 /*** Sending/receiving packets ***/
589 static ALWAYS_INLINE uint32_t random_xid(void)
594 /* Initialize the packet with the proper defaults */
595 static void init_packet(struct dhcp_packet *packet, char type)
599 /* Fill in: op, htype, hlen, cookie fields; message type option: */
600 udhcp_init_header(packet, type);
602 packet->xid = random_xid();
604 client_config.last_secs = monotonic_sec();
605 if (client_config.first_secs == 0)
606 client_config.first_secs = client_config.last_secs;
607 secs = client_config.last_secs - client_config.first_secs;
608 packet->secs = htons(secs);
610 memcpy(packet->chaddr, client_config.client_mac, 6);
611 if (client_config.clientid)
612 udhcp_add_binary_option(packet, client_config.clientid);
615 static void add_client_options(struct dhcp_packet *packet)
619 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
621 /* Add a "param req" option with the list of options we'd like to have
622 * from stubborn DHCP servers. Pull the data from the struct in common.c.
623 * No bounds checking because it goes towards the head of the packet. */
624 end = udhcp_end_option(packet->options);
626 for (i = 1; i < DHCP_END; i++) {
627 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
628 packet->options[end + OPT_DATA + len] = i;
633 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
634 packet->options[end + OPT_LEN] = len;
635 packet->options[end + OPT_DATA + len] = DHCP_END;
638 if (client_config.vendorclass)
639 udhcp_add_binary_option(packet, client_config.vendorclass);
640 if (client_config.hostname)
641 udhcp_add_binary_option(packet, client_config.hostname);
642 if (client_config.fqdn)
643 udhcp_add_binary_option(packet, client_config.fqdn);
645 /* Request broadcast replies if we have no IP addr */
646 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
647 packet->flags |= htons(BROADCAST_FLAG);
649 /* Add -x options if any */
651 struct option_set *curr = client_config.options;
653 udhcp_add_binary_option(packet, curr->data);
656 // if (client_config.sname)
657 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
658 // if (client_config.boot_file)
659 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
662 // This will be needed if we remove -V VENDOR_STR in favor of
663 // -x vendor:VENDOR_STR
664 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
665 // /* not set, set the default vendor ID */
666 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
670 * 4.4.4 Use of broadcast and unicast
672 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
673 * messages, unless the client knows the address of a DHCP server.
674 * The client unicasts DHCPRELEASE messages to the server. Because
675 * the client is declining the use of the IP address supplied by the server,
676 * the client broadcasts DHCPDECLINE messages.
678 * When the DHCP client knows the address of a DHCP server, in either
679 * INIT or REBOOTING state, the client may use that address
680 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
681 * The client may also use unicast to send DHCPINFORM messages
682 * to a known DHCP server. If the client receives no response to DHCP
683 * messages sent to the IP address of a known DHCP server, the DHCP
684 * client reverts to using the IP broadcast address.
687 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet, uint32_t src_nip)
689 return udhcp_send_raw_packet(packet,
690 /*src*/ src_nip, CLIENT_PORT,
691 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
692 client_config.ifindex);
695 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
698 /* Without MSG_DONTROUTE, the packet was seen routed over
699 * _other interface_ if server ID is bogus (example: 1.1.1.1).
701 return udhcp_send_kernel_packet(packet,
704 /*send_flags: "to hosts only on directly connected networks" */ MSG_DONTROUTE
707 return raw_bcast_from_client_config_ifindex(packet, ciaddr);
710 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
711 /* NOINLINE: limit stack usage in caller */
712 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
714 struct dhcp_packet packet;
716 /* Fill in: op, htype, hlen, cookie, chaddr fields,
717 * random xid field (we override it below),
718 * client-id option (unless -C), message type option:
720 init_packet(&packet, DHCPDISCOVER);
724 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
726 /* Add options: maxsize,
727 * optionally: hostname, fqdn, vendorclass,
728 * "param req" option according to -O, options specified with -x
730 add_client_options(&packet);
732 bb_error_msg("sending %s", "discover");
733 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
736 /* Broadcast a DHCP request message */
737 /* RFC 2131 3.1 paragraph 3:
738 * "The client _broadcasts_ a DHCPREQUEST message..."
740 /* NOINLINE: limit stack usage in caller */
741 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
743 struct dhcp_packet packet;
744 struct in_addr temp_addr;
747 * RFC 2131 4.3.2 DHCPREQUEST message
749 * If the DHCPREQUEST message contains a 'server identifier'
750 * option, the message is in response to a DHCPOFFER message.
751 * Otherwise, the message is a request to verify or extend an
752 * existing lease. If the client uses a 'client identifier'
753 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
754 * in all subsequent messages. If the client included a list
755 * of requested parameters in a DHCPDISCOVER message, it MUST
756 * include that list in all subsequent messages.
758 /* Fill in: op, htype, hlen, cookie, chaddr fields,
759 * random xid field (we override it below),
760 * client-id option (unless -C), message type option:
762 init_packet(&packet, DHCPREQUEST);
765 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
767 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
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 temp_addr.s_addr = requested;
776 bb_error_msg("sending select for %s", inet_ntoa(temp_addr));
777 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
780 /* Unicast or broadcast a DHCP renew message */
781 /* NOINLINE: limit stack usage in caller */
782 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
784 struct dhcp_packet packet;
785 struct in_addr temp_addr;
788 * RFC 2131 4.3.2 DHCPREQUEST message
790 * DHCPREQUEST generated during RENEWING state:
792 * 'server identifier' MUST NOT be filled in, 'requested IP address'
793 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
794 * client's IP address. In this situation, the client is completely
795 * configured, and is trying to extend its lease. This message will
796 * be unicast, so no relay agents will be involved in its
797 * transmission. Because 'giaddr' is therefore not filled in, the
798 * DHCP server will trust the value in 'ciaddr', and use it when
799 * replying to the client.
801 /* Fill in: op, htype, hlen, cookie, chaddr fields,
802 * random xid field (we override it below),
803 * client-id option (unless -C), message type option:
805 init_packet(&packet, DHCPREQUEST);
808 packet.ciaddr = ciaddr;
810 /* Add options: maxsize,
811 * optionally: hostname, fqdn, vendorclass,
812 * "param req" option according to -O, and options specified with -x
814 add_client_options(&packet);
816 temp_addr.s_addr = server;
817 bb_error_msg("sending renew to %s", inet_ntoa(temp_addr));
818 return bcast_or_ucast(&packet, ciaddr, server);
821 #if ENABLE_FEATURE_UDHCPC_ARPING
822 /* Broadcast a DHCP decline message */
823 /* NOINLINE: limit stack usage in caller */
824 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
826 struct dhcp_packet packet;
828 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
829 * client-id option (unless -C), message type option:
831 init_packet(&packet, DHCPDECLINE);
834 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
835 * but in case the server is buggy and wants DHCPDECLINE's xid
836 * to match the xid which started entire handshake,
837 * we use the same xid we used in initial DHCPDISCOVER:
841 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
842 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
844 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
846 bb_error_msg("sending %s", "decline");
847 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
851 /* Unicast a DHCP release message */
852 static int send_release(uint32_t server, uint32_t ciaddr)
854 struct dhcp_packet packet;
856 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
857 * client-id option (unless -C), message type option:
859 init_packet(&packet, DHCPRELEASE);
861 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
862 packet.ciaddr = ciaddr;
864 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
866 bb_error_msg("sending %s", "release");
867 /* Note: normally we unicast here since "server" is not zero.
868 * However, there _are_ people who run "address-less" DHCP servers,
869 * and reportedly ISC dhcp client and Windows allow that.
871 return bcast_or_ucast(&packet, ciaddr, server);
874 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
875 /* NOINLINE: limit stack usage in caller */
876 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
879 struct ip_udp_dhcp_packet packet;
881 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
884 struct cmsghdr *cmsg;
886 /* used to use just safe_read(fd, &packet, sizeof(packet))
887 * but we need to check for TP_STATUS_CSUMNOTREADY :(
889 iov.iov_base = &packet;
890 iov.iov_len = sizeof(packet);
891 memset(&msg, 0, sizeof(msg));
894 msg.msg_control = cmsgbuf;
895 msg.msg_controllen = sizeof(cmsgbuf);
897 bytes = recvmsg(fd, &msg, 0);
901 log1("packet read error, ignoring");
902 /* NB: possible down interface, etc. Caller should pause. */
903 return bytes; /* returns -1 */
908 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
909 log1("packet is too short, ignoring");
913 if (bytes < ntohs(packet.ip.tot_len)) {
914 /* packet is bigger than sizeof(packet), we did partial read */
915 log1("oversized packet, ignoring");
919 /* ignore any extra garbage bytes */
920 bytes = ntohs(packet.ip.tot_len);
922 /* make sure its the right packet for us, and that it passes sanity checks */
923 if (packet.ip.protocol != IPPROTO_UDP
924 || packet.ip.version != IPVERSION
925 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
926 || packet.udp.dest != htons(CLIENT_PORT)
927 /* || bytes > (int) sizeof(packet) - can't happen */
928 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
930 log1("unrelated/bogus packet, ignoring");
934 /* verify IP checksum */
935 check = packet.ip.check;
937 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
938 log1("bad IP header checksum, ignoring");
942 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
943 if (cmsg->cmsg_level == SOL_PACKET
944 && cmsg->cmsg_type == PACKET_AUXDATA
946 /* some VMs don't checksum UDP and TCP data
947 * they send to the same physical machine,
948 * here we detect this case:
950 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
951 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
952 goto skip_udp_sum_check;
956 /* verify UDP checksum. IP header has to be modified for this */
957 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
958 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
959 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
960 check = packet.udp.check;
961 packet.udp.check = 0;
962 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
963 log1("packet with bad UDP checksum received, ignoring");
968 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
969 bb_error_msg("packet with bad magic, ignoring");
973 log1("received %s", "a packet");
974 udhcp_dump_packet(&packet.data);
976 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
977 memcpy(dhcp_pkt, &packet.data, bytes);
984 static int sockfd = -1;
986 #define LISTEN_NONE 0
987 #define LISTEN_KERNEL 1
989 static smallint listen_mode;
991 /* initial state: (re)start DHCP negotiation */
992 #define INIT_SELECTING 0
993 /* discover was sent, DHCPOFFER reply received */
995 /* select/renew was sent, DHCPACK reply received */
997 /* half of lease passed, want to renew it by sending unicast renew requests */
999 /* renew requests were not answered, lease is almost over, send broadcast renew */
1001 /* manually requested renew (SIGUSR1) */
1002 #define RENEW_REQUESTED 5
1003 /* release, possibly manually requested (SIGUSR2) */
1005 static smallint state;
1007 static int udhcp_raw_socket(int ifindex)
1010 struct sockaddr_ll sock;
1012 log2("opening raw socket on ifindex %d", ifindex);
1014 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
1016 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
1017 * ETH_P_IP: want to receive only packets with IPv4 eth type
1019 log2("got raw socket fd");
1021 memset(&sock, 0, sizeof(sock)); /* let's be deterministic */
1022 sock.sll_family = AF_PACKET;
1023 sock.sll_protocol = htons(ETH_P_IP);
1024 sock.sll_ifindex = ifindex;
1025 /*sock.sll_hatype = ARPHRD_???;*/
1026 /*sock.sll_pkttype = PACKET_???;*/
1027 /*sock.sll_halen = ???;*/
1028 /*sock.sll_addr[8] = ???;*/
1029 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1031 #if 0 /* Several users reported breakage when BPF filter is used */
1032 if (CLIENT_PORT == 68) {
1033 /* Use only if standard port is in use */
1035 * I've selected not to see LL header, so BPF doesn't see it, too.
1036 * The filter may also pass non-IP and non-ARP packets, but we do
1037 * a more complete check when receiving the message in userspace.
1039 * and filter shamelessly stolen from:
1041 * http://www.flamewarmaster.de/software/dhcpclient/
1043 * There are a few other interesting ideas on that page (look under
1044 * "Motivation"). Use of netlink events is most interesting. Think
1045 * of various network servers listening for events and reconfiguring.
1046 * That would obsolete sending HUP signals and/or make use of restarts.
1048 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1051 static const struct sock_filter filter_instr[] = {
1052 /* load 9th byte (protocol) */
1053 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1054 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1055 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1056 /* L1: load halfword from offset 6 (flags and frag offset) */
1057 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1058 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1059 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1060 /* L2: skip IP header (load index reg with header len) */
1061 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1062 /* load udp destination port from halfword[header_len + 2] */
1063 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1064 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1065 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1066 /* L3: accept packet ("accept 0x7fffffff bytes") */
1067 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1068 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1069 /* L4: discard packet ("accept zero bytes") */
1070 BPF_STMT(BPF_RET|BPF_K, 0),
1072 static const struct sock_fprog filter_prog = {
1073 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1074 /* casting const away: */
1075 .filter = (struct sock_filter *) filter_instr,
1077 /* Ignoring error (kernel may lack support for this) */
1078 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1079 sizeof(filter_prog)) >= 0)
1080 log1("attached filter to raw socket fd"); // log?
1084 if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1085 if (errno != ENOPROTOOPT)
1086 log1("can't set PACKET_AUXDATA on raw socket");
1089 log1("created raw socket");
1094 static void change_listen_mode(int new_mode)
1096 log1("entering listen mode: %s",
1097 new_mode != LISTEN_NONE
1098 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1102 listen_mode = new_mode;
1107 if (new_mode == LISTEN_KERNEL)
1108 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1109 else if (new_mode != LISTEN_NONE)
1110 sockfd = udhcp_raw_socket(client_config.ifindex);
1111 /* else LISTEN_NONE: sockfd stays closed */
1114 /* Called only on SIGUSR1 */
1115 static void perform_renew(void)
1117 bb_error_msg("performing DHCP renew");
1120 change_listen_mode(LISTEN_KERNEL);
1123 state = RENEW_REQUESTED;
1125 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1126 udhcp_run_script(NULL, "deconfig");
1129 change_listen_mode(LISTEN_RAW);
1130 state = INIT_SELECTING;
1132 case INIT_SELECTING:
1137 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1139 char buffer[sizeof("255.255.255.255")];
1140 struct in_addr temp_addr;
1142 /* send release packet */
1144 || state == RENEWING
1145 || state == REBINDING
1146 || state == RENEW_REQUESTED
1148 temp_addr.s_addr = server_addr;
1149 strcpy(buffer, inet_ntoa(temp_addr));
1150 temp_addr.s_addr = requested_ip;
1151 bb_error_msg("unicasting a release of %s to %s",
1152 inet_ntoa(temp_addr), buffer);
1153 send_release(server_addr, requested_ip); /* unicast */
1155 bb_error_msg("entering released state");
1157 * We can be here on: SIGUSR2,
1158 * or on exit (SIGTERM) and -R "release on quit" is specified.
1159 * Users requested to be notified in all cases, even if not in one
1160 * of the states above.
1162 udhcp_run_script(NULL, "deconfig");
1164 change_listen_mode(LISTEN_NONE);
1168 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1171 int len = strnlen(str, 255);
1172 storage = xzalloc(len + extra + OPT_DATA);
1173 storage[OPT_CODE] = code;
1174 storage[OPT_LEN] = len + extra;
1175 memcpy(storage + extra + OPT_DATA, str, len);
1180 static void client_background(void)
1183 logmode &= ~LOGMODE_STDIO;
1184 /* rewrite pidfile, as our pid is different now */
1185 write_pidfile(client_config.pidfile);
1189 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1190 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1192 //usage:# define IF_UDHCP_VERBOSE(...)
1194 //usage:#define udhcpc_trivial_usage
1195 //usage: "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1196 //usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1197 //usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1198 //usage:#define udhcpc_full_usage "\n"
1199 //usage: "\n -i IFACE Interface to use (default eth0)"
1200 //usage: IF_FEATURE_UDHCP_PORT(
1201 //usage: "\n -P PORT Use PORT (default 68)"
1203 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1204 //usage: "\n -p FILE Create pidfile"
1205 //usage: "\n -B Request broadcast replies"
1206 //usage: "\n -t N Send up to N discover packets (default 3)"
1207 //usage: "\n -T SEC Pause between packets (default 3)"
1208 //usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1209 //usage: "\n -n Exit if lease is not obtained"
1210 //usage: "\n -q Exit after obtaining lease"
1211 //usage: "\n -R Release IP on exit"
1212 //usage: "\n -f Run in foreground"
1213 //usage: USE_FOR_MMU(
1214 //usage: "\n -b Background if lease is not obtained"
1216 //usage: "\n -S Log to syslog too"
1217 //usage: IF_FEATURE_UDHCPC_ARPING(
1218 //usage: "\n -a[MSEC] Validate offered address with ARP ping"
1220 //usage: "\n -r IP Request this IP address"
1221 //usage: "\n -o Don't request any options (unless -O is given)"
1222 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1223 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1224 //usage: "\n Examples of string, numeric, and hex byte opts:"
1225 //usage: "\n -x hostname:bbox - option 12"
1226 //usage: "\n -x lease:3600 - option 51 (lease time)"
1227 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1228 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1229 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1230 //usage: "\n -C Don't send MAC as client identifier"
1231 //usage: IF_UDHCP_VERBOSE(
1232 //usage: "\n -v Verbose"
1234 //usage: "\nSignals:"
1235 //usage: "\n USR1 Renew lease"
1236 //usage: "\n USR2 Release lease"
1239 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1240 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1243 const char *str_V, *str_h, *str_F, *str_r;
1244 IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1245 IF_FEATURE_UDHCP_PORT(char *str_P;)
1246 void *clientid_mac_ptr;
1247 llist_t *list_O = NULL;
1248 llist_t *list_x = NULL;
1249 int tryagain_timeout = 20;
1250 int discover_timeout = 3;
1251 int discover_retries = 3;
1252 uint32_t server_addr = server_addr; /* for compiler */
1253 uint32_t requested_ip = 0;
1254 uint32_t xid = xid; /* for compiler */
1256 int timeout; /* must be signed */
1257 unsigned already_waited_sec;
1259 IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1262 setup_common_bufsiz();
1264 /* Default options */
1265 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1266 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1267 client_config.interface = "eth0";
1268 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1269 str_V = "udhcp "BB_VER;
1271 /* Parse command line */
1272 opt = getopt32long(argv, "^"
1273 /* O,x: list; -T,-t,-A take numeric param */
1274 "CV:H:h:F:i:np:qRr:s:T:+t:+SA:+O:*ox:*fB"
1276 IF_FEATURE_UDHCPC_ARPING("a::")
1277 IF_FEATURE_UDHCP_PORT("P:")
1279 "\0" IF_UDHCP_VERBOSE("vv") /* -v is a counter */
1281 , &str_V, &str_h, &str_h, &str_F
1282 , &client_config.interface, &client_config.pidfile /* i,p */
1284 , &client_config.script /* s */
1285 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1288 IF_FEATURE_UDHCPC_ARPING(, &str_a)
1289 IF_FEATURE_UDHCP_PORT(, &str_P)
1290 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1292 if (opt & (OPT_h|OPT_H)) {
1294 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1295 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1298 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1299 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1300 /* Flag bits: 0000NEOS
1301 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1302 * O: 1 = Server indicates to client that DNS has been updated regardless
1303 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1304 * not "host.domain.com". Format 0 is obsolete.
1305 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1306 * Two [0] bytes which follow are deprecated and must be 0.
1308 client_config.fqdn[OPT_DATA + 0] = 0x1;
1309 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1310 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1313 requested_ip = inet_addr(str_r);
1314 #if ENABLE_FEATURE_UDHCP_PORT
1316 CLIENT_PORT = xatou16(str_P);
1317 SERVER_PORT = CLIENT_PORT - 1;
1320 IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1322 char *optstr = llist_pop(&list_O);
1323 unsigned n = bb_strtou(optstr, NULL, 0);
1324 if (errno || n > 254) {
1325 n = udhcp_option_idx(optstr, dhcp_option_strings);
1326 n = dhcp_optflags[n].code;
1328 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1330 if (!(opt & OPT_o)) {
1332 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1333 if (dhcp_optflags[i].flags & OPTION_REQ) {
1334 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1339 char *optstr = llist_pop(&list_x);
1340 char *colon = strchr(optstr, ':');
1343 /* now it looks similar to udhcpd's config file line:
1344 * "optname optval", using the common routine: */
1345 udhcp_str2optset(optstr, &client_config.options, dhcp_optflags, dhcp_option_strings);
1347 *colon = ':'; /* restore it for NOMMU reexec */
1350 if (udhcp_read_interface(client_config.interface,
1351 &client_config.ifindex,
1353 client_config.client_mac)
1358 clientid_mac_ptr = NULL;
1359 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1360 /* not suppressed and not set, set the default client ID */
1361 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1362 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1363 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1364 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1366 if (str_V[0] != '\0') {
1367 // can drop -V, str_V, client_config.vendorclass,
1368 // but need to add "vendor" to the list of recognized
1369 // string opts for this to work;
1370 // and need to tweak add_client_options() too...
1371 // ...so the question is, should we?
1372 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1373 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1377 /* on NOMMU reexec (i.e., background) early */
1378 if (!(opt & OPT_f)) {
1379 bb_daemonize_or_rexec(0 /* flags */, argv);
1380 logmode = LOGMODE_NONE;
1384 openlog(applet_name, LOG_PID, LOG_DAEMON);
1385 logmode |= LOGMODE_SYSLOG;
1388 /* Make sure fd 0,1,2 are open */
1389 bb_sanitize_stdio();
1390 /* Equivalent of doing a fflush after every \n */
1392 /* Create pidfile */
1393 write_pidfile(client_config.pidfile);
1394 /* Goes to stdout (unless NOMMU) and possibly syslog */
1395 bb_error_msg("started, v"BB_VER);
1396 /* Set up the signal pipe */
1398 /* We want random_xid to be random... */
1399 srand(monotonic_us());
1401 state = INIT_SELECTING;
1402 udhcp_run_script(NULL, "deconfig");
1403 change_listen_mode(LISTEN_RAW);
1406 already_waited_sec = 0;
1408 /* Main event loop. select() waits on signal pipe and possibly
1410 * "continue" statements in code below jump to the top of the loop.
1414 struct pollfd pfds[2];
1415 struct dhcp_packet packet;
1416 /* silence "uninitialized!" warning */
1417 unsigned timestamp_before_wait = timestamp_before_wait;
1419 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1421 /* Was opening raw or udp socket here
1422 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1423 * but on fast network renew responses return faster
1424 * than we open sockets. Thus this code is moved
1425 * to change_listen_mode(). Thus we open listen socket
1426 * BEFORE we send renew request (see "case BOUND:"). */
1428 udhcp_sp_fd_set(pfds, sockfd);
1430 tv = timeout - already_waited_sec;
1432 /* If we already timed out, fall through with retval = 0, else... */
1434 log1("waiting %u seconds", tv);
1435 timestamp_before_wait = (unsigned)monotonic_sec();
1436 retval = poll(pfds, 2, tv < INT_MAX/1000 ? tv * 1000 : INT_MAX);
1438 /* EINTR? A signal was caught, don't panic */
1439 if (errno == EINTR) {
1440 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1443 /* Else: an error occurred, panic! */
1444 bb_perror_msg_and_die("poll");
1448 /* If timeout dropped to zero, time to become active:
1449 * resend discover/renew/whatever
1452 /* When running on a bridge, the ifindex may have changed
1453 * (e.g. if member interfaces were added/removed
1454 * or if the status of the bridge changed).
1455 * Refresh ifindex and client_mac:
1457 if (udhcp_read_interface(client_config.interface,
1458 &client_config.ifindex,
1460 client_config.client_mac)
1462 goto ret0; /* iface is gone? */
1464 if (clientid_mac_ptr)
1465 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1467 /* We will restart the wait in any case */
1468 already_waited_sec = 0;
1471 case INIT_SELECTING:
1472 if (!discover_retries || packet_num < discover_retries) {
1473 if (packet_num == 0)
1476 send_discover(xid, requested_ip);
1477 timeout = discover_timeout;
1482 udhcp_run_script(NULL, "leasefail");
1483 #if BB_MMU /* -b is not supported on NOMMU */
1484 if (opt & OPT_b) { /* background if no lease */
1485 bb_error_msg("no lease, forking to background");
1486 client_background();
1487 /* do not background again! */
1488 opt = ((opt & ~OPT_b) | OPT_f);
1491 if (opt & OPT_n) { /* abort if no lease */
1492 bb_error_msg("no lease, failing");
1496 /* wait before trying again */
1497 timeout = tryagain_timeout;
1501 if (packet_num < 3) {
1502 /* send broadcast select packet */
1503 send_select(xid, server_addr, requested_ip);
1504 timeout = discover_timeout;
1508 /* Timed out, go back to init state.
1509 * "discover...select...discover..." loops
1510 * were seen in the wild. Treat them similarly
1511 * to "no response to discover" case */
1512 change_listen_mode(LISTEN_RAW);
1513 state = INIT_SELECTING;
1516 /* 1/2 lease passed, enter renewing state */
1518 client_config.first_secs = 0; /* make secs field count from 0 */
1519 change_listen_mode(LISTEN_KERNEL);
1520 log1("entering renew state");
1521 /* fall right through */
1522 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1523 case_RENEW_REQUESTED:
1526 /* send an unicast renew request */
1527 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1528 * a new UDP socket for sending inside send_renew.
1529 * I hazard to guess existing listening socket
1530 * is somehow conflicting with it, but why is it
1531 * not deterministic then?! Strange.
1532 * Anyway, it does recover by eventually failing through
1533 * into INIT_SELECTING state.
1535 if (send_renew(xid, server_addr, requested_ip) >= 0) {
1537 //TODO: the timeout to receive an answer for our renew should not be selected
1538 //with "timeout = lease_seconds / 2; ...; timeout = timeout / 2": it is often huge.
1539 //Waiting e.g. 4*3600 seconds for a reply does not make sense
1540 //(if reply isn't coming, we keep an open socket for hours),
1541 //it should be something like 10 seconds.
1542 //Also, it's probably best to try sending renew in kernel mode a few (3-5) times
1543 //and fall back to raw mode if it does not work.
1546 /* else: error sending.
1547 * example: ENETUNREACH seen with server
1548 * which gave us bogus server ID 1.1.1.1
1549 * which wasn't reachable (and probably did not exist).
1552 /* Timed out or error, enter rebinding state */
1553 log1("entering rebinding state");
1555 /* fall right through */
1557 /* Switch to bcast receive */
1558 change_listen_mode(LISTEN_RAW);
1559 /* Lease is *really* about to run out,
1560 * try to find DHCP server using broadcast */
1562 /* send a broadcast renew request */
1563 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1567 /* Timed out, enter init state */
1568 bb_error_msg("lease lost, entering init state");
1569 udhcp_run_script(NULL, "deconfig");
1570 state = INIT_SELECTING;
1571 client_config.first_secs = 0; /* make secs field count from 0 */
1572 /*timeout = 0; - already is */
1575 /* case RELEASED: */
1577 /* yah, I know, *you* say it would never happen */
1579 continue; /* back to main loop */
1580 } /* if select timed out */
1582 /* select() didn't timeout, something happened */
1584 /* Is it a signal? */
1585 /* note: udhcp_sp_read checks poll result before reading */
1586 switch (udhcp_sp_read(pfds)) {
1588 client_config.first_secs = 0; /* make secs field count from 0 */
1589 already_waited_sec = 0;
1591 if (state == RENEW_REQUESTED) {
1592 /* We might be either on the same network
1593 * (in which case renew might work),
1594 * or we might be on a completely different one
1595 * (in which case renew won't ever succeed).
1596 * For the second case, must make sure timeout
1597 * is not too big, or else we can send
1598 * futile renew requests for hours.
1599 * (Ab)use -A TIMEOUT value (usually 20 sec)
1600 * as a cap on the timeout.
1602 if (timeout > tryagain_timeout)
1603 timeout = tryagain_timeout;
1604 goto case_RENEW_REQUESTED;
1606 /* Start things over */
1608 /* Kill any timeouts, user wants this to hurry along */
1612 perform_release(server_addr, requested_ip);
1616 bb_error_msg("received %s", "SIGTERM");
1620 /* Is it a packet? */
1621 if (listen_mode == LISTEN_NONE || !pfds[1].revents)
1627 /* A packet is ready, read it */
1628 if (listen_mode == LISTEN_KERNEL)
1629 len = udhcp_recv_kernel_packet(&packet, sockfd);
1631 len = udhcp_recv_raw_packet(&packet, sockfd);
1633 /* Error is severe, reopen socket */
1634 bb_error_msg("read error: "STRERROR_FMT", reopening socket" STRERROR_ERRNO);
1635 sleep(discover_timeout); /* 3 seconds by default */
1636 change_listen_mode(listen_mode); /* just close and reopen */
1638 /* If this packet will turn out to be unrelated/bogus,
1639 * we will go back and wait for next one.
1640 * Be sure timeout is properly decreased. */
1641 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1646 if (packet.xid != xid) {
1647 log1("xid %x (our is %x), ignoring packet",
1648 (unsigned)packet.xid, (unsigned)xid);
1652 /* Ignore packets that aren't for us */
1653 if (packet.hlen != 6
1654 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1656 //FIXME: need to also check that last 10 bytes are zero
1657 log1("chaddr does not match, ignoring packet"); // log2?
1661 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1662 if (message == NULL) {
1663 bb_error_msg("no message type option, ignoring packet");
1668 case INIT_SELECTING:
1669 /* Must be a DHCPOFFER */
1670 if (*message == DHCPOFFER) {
1673 /* What exactly is server's IP? There are several values.
1674 * Example DHCP offer captured with tchdump:
1676 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1678 * Your-IP 10.34.25.202
1679 * Server-IP 10.34.32.125 // "next server" IP
1680 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1682 * DHCP-Message Option 53, length 1: Offer
1683 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1684 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1686 * We think that real server IP (one to use in renew/release)
1687 * is one in Server-ID option. But I am not 100% sure.
1688 * IP header's src and Gateway-IP (same in this example)
1690 * "Next server" and router are definitely wrong ones to use, though...
1692 /* We used to ignore pcakets without DHCP_SERVER_ID.
1693 * I've got user reports from people who run "address-less" servers.
1694 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1695 * They say ISC DHCP client supports this case.
1698 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1700 bb_error_msg("no server ID, using 0.0.0.0");
1702 /* it IS unaligned sometimes, don't "optimize" */
1703 move_from_unaligned32(server_addr, temp);
1705 /*xid = packet.xid; - already is */
1706 requested_ip = packet.yiaddr;
1708 /* enter requesting state */
1712 already_waited_sec = 0;
1717 case RENEW_REQUESTED:
1719 if (*message == DHCPACK) {
1721 uint32_t lease_seconds;
1722 struct in_addr temp_addr;
1725 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1727 bb_error_msg("no lease time with ACK, using 1 hour lease");
1728 lease_seconds = 60 * 60;
1730 /* it IS unaligned sometimes, don't "optimize" */
1731 move_from_unaligned32(lease_seconds, temp);
1732 lease_seconds = ntohl(lease_seconds);
1733 /* paranoia: must not be too small and not prone to overflows */
1734 if (lease_seconds < 0x10)
1735 lease_seconds = 0x10;
1736 if (lease_seconds > 0x7fffffff / 1000)
1737 lease_seconds = 0x7fffffff / 1000;
1739 #if ENABLE_FEATURE_UDHCPC_ARPING
1741 /* RFC 2131 3.1 paragraph 5:
1742 * "The client receives the DHCPACK message with configuration
1743 * parameters. The client SHOULD perform a final check on the
1744 * parameters (e.g., ARP for allocated network address), and notes
1745 * the duration of the lease specified in the DHCPACK message. At this
1746 * point, the client is configured. If the client detects that the
1747 * address is already in use (e.g., through the use of ARP),
1748 * the client MUST send a DHCPDECLINE message to the server and restarts
1749 * the configuration process..." */
1750 if (!arpping(packet.yiaddr,
1753 client_config.client_mac,
1754 client_config.interface,
1757 bb_error_msg("offered address is in use "
1758 "(got ARP reply), declining");
1759 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1761 if (state != REQUESTING)
1762 udhcp_run_script(NULL, "deconfig");
1763 change_listen_mode(LISTEN_RAW);
1764 state = INIT_SELECTING;
1765 client_config.first_secs = 0; /* make secs field count from 0 */
1767 timeout = tryagain_timeout;
1769 already_waited_sec = 0;
1770 continue; /* back to main loop */
1774 /* enter bound state */
1775 temp_addr.s_addr = packet.yiaddr;
1776 bb_error_msg("lease of %s obtained, lease time %u",
1777 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1778 requested_ip = packet.yiaddr;
1780 start = monotonic_sec();
1781 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1782 already_waited_sec = (unsigned)monotonic_sec() - start;
1783 timeout = lease_seconds / 2;
1784 if ((unsigned)timeout < already_waited_sec) {
1785 /* Something went wrong. Back to discover state */
1786 timeout = already_waited_sec = 0;
1790 change_listen_mode(LISTEN_NONE);
1791 if (opt & OPT_q) { /* quit after lease */
1794 /* future renew failures should not exit (JM) */
1796 #if BB_MMU /* NOMMU case backgrounded earlier */
1797 if (!(opt & OPT_f)) {
1798 client_background();
1799 /* do not background again! */
1800 opt = ((opt & ~OPT_b) | OPT_f);
1803 /* make future renew packets use different xid */
1804 /* xid = random_xid(); ...but why bother? */
1806 continue; /* back to main loop */
1808 if (*message == DHCPNAK) {
1809 /* If network has more than one DHCP server,
1810 * "wrong" server can reply first, with a NAK.
1811 * Do not interpret it as a NAK from "our" server.
1813 if (server_addr != 0) {
1817 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1820 log1("received DHCP NAK with wrong"
1821 " server ID, ignoring packet");
1824 move_from_unaligned32(svid, temp);
1825 if (svid != server_addr)
1826 goto non_matching_svid;
1828 /* return to init state */
1829 bb_error_msg("received %s", "DHCP NAK");
1830 udhcp_run_script(&packet, "nak");
1831 if (state != REQUESTING)
1832 udhcp_run_script(NULL, "deconfig");
1833 change_listen_mode(LISTEN_RAW);
1834 sleep(3); /* avoid excessive network traffic */
1835 state = INIT_SELECTING;
1836 client_config.first_secs = 0; /* make secs field count from 0 */
1840 already_waited_sec = 0;
1843 /* case BOUND: - ignore all packets */
1844 /* case RELEASED: - ignore all packets */
1846 /* back to main loop */
1847 } /* for (;;) - main loop ends */
1850 if (opt & OPT_R) /* release on quit */
1851 perform_release(server_addr, requested_ip);
1854 /*if (client_config.pidfile) - remove_pidfile has its own check */
1855 remove_pidfile(client_config.pidfile);