1 /* vi: set sw=4 ts=4: */
4 * Russ Dill <Russ.Dill@asu.edu> July 2001
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
20 //applet:IF_UDHCPC(APPLET(udhcpc, BB_DIR_SBIN, BB_SUID_DROP))
22 //kbuild:lib-$(CONFIG_UDHCPC) += common.o packet.o signalpipe.o socket.o
23 //kbuild:lib-$(CONFIG_UDHCPC) += dhcpc.o
24 //kbuild:lib-$(CONFIG_FEATURE_UDHCPC_ARPING) += arpping.o
25 //kbuild:lib-$(CONFIG_FEATURE_UDHCP_RFC3397) += domain_codec.o
28 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
29 #define WANT_PIDFILE 1
34 #include <netinet/if_ether.h>
35 #include <linux/filter.h>
36 #include <linux/if_packet.h>
38 #ifndef PACKET_AUXDATA
39 # define PACKET_AUXDATA 8
40 struct tpacket_auxdata {
52 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
56 static const char udhcpc_longopts[] ALIGN1 =
57 "clientid-none\0" No_argument "C"
58 "vendorclass\0" Required_argument "V"
59 "hostname\0" Required_argument "H"
60 "fqdn\0" Required_argument "F"
61 "interface\0" Required_argument "i"
62 "now\0" No_argument "n"
63 "pidfile\0" Required_argument "p"
64 "quit\0" No_argument "q"
65 "release\0" No_argument "R"
66 "request\0" Required_argument "r"
67 "script\0" Required_argument "s"
68 "timeout\0" Required_argument "T"
69 "retries\0" Required_argument "t"
70 "tryagain\0" Required_argument "A"
71 "syslog\0" No_argument "S"
72 "request-option\0" Required_argument "O"
73 "no-default-options\0" No_argument "o"
74 "foreground\0" No_argument "f"
76 "background\0" No_argument "b"
78 "broadcast\0" No_argument "B"
79 IF_FEATURE_UDHCPC_ARPING("arping\0" Optional_argument "a")
80 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
83 /* Must match getopt32 option string order */
106 /* The rest has variable bit positions, need to be clever */
108 USE_FOR_MMU( OPTBIT_b,)
109 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
110 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
111 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
112 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
113 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
117 /*** Script execution code ***/
119 /* get a rough idea of how long an option will be (rounding up...) */
120 static const uint8_t len_of_option_as_string[] ALIGN1 = {
121 [OPTION_IP ] = sizeof("255.255.255.255 "),
122 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
123 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
124 [OPTION_6RD ] = sizeof("132 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
125 [OPTION_STRING ] = 1,
126 [OPTION_STRING_HOST ] = 1,
127 #if ENABLE_FEATURE_UDHCP_RFC3397
128 [OPTION_DNS_STRING ] = 1, /* unused */
129 /* Hmmm, this severely overestimates size if SIP_SERVERS option
130 * is in domain name form: N-byte option in binary form
131 * mallocs ~16*N bytes. But it is freed almost at once.
133 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
135 // [OPTION_BOOLEAN ] = sizeof("yes "),
136 [OPTION_U8 ] = sizeof("255 "),
137 [OPTION_U16 ] = sizeof("65535 "),
138 // [OPTION_S16 ] = sizeof("-32768 "),
139 [OPTION_U32 ] = sizeof("4294967295 "),
140 [OPTION_S32 ] = sizeof("-2147483684 "),
143 /* note: ip is a pointer to an IP in network order, possibly misaliged */
144 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
146 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
149 /* really simple implementation, just count the bits */
150 static int mton(uint32_t mask)
153 mask = ntohl(mask); /* 111110000-like bit pattern */
161 #if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
162 /* Check if a given label represents a valid DNS label
163 * Return pointer to the first character after the label
164 * (NUL or dot) upon success, NULL otherwise.
167 /* We don't need to be particularly anal. For example, allowing _, hyphen
168 * at the end, or leading and trailing dots would be ok, since it
169 * can't be used for attacks. (Leading hyphen can be, if someone uses
171 * in the script: then hostname may be treated as an option)
173 static const char *valid_domain_label(const char *label)
182 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
183 if (ch < '0' || ch > '9') {
184 if (ch == '\0' || ch == '.')
186 /* DNS allows only '-', but we are more permissive */
187 if (ch != '-' && ch != '_')
194 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
199 /* Check if a given name represents a valid DNS name */
200 /* See RFC1035, 2.3.1 */
201 static int good_hostname(const char *name)
203 //const char *start = name;
206 name = valid_domain_label(name);
212 //return ((name - start) < 1025); /* NS_MAXDNAME */
215 return 1; // We allow trailing dot too
219 # define good_hostname(name) 1
222 /* Create "opt_name=opt_value" string */
223 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
225 unsigned upper_length;
226 int len, type, optlen;
229 /* option points to OPT_DATA, need to go back to get OPT_LEN */
230 len = option[-OPT_DATA + OPT_LEN];
232 type = optflag->flags & OPTION_TYPE_MASK;
233 optlen = dhcp_option_lengths[type];
234 upper_length = len_of_option_as_string[type]
235 * ((unsigned)(len + optlen) / (unsigned)optlen);
237 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
238 dest += sprintf(ret, "%s=", opt_name);
240 while (len >= optlen) {
244 dest += sprint_nip(dest, "", option);
245 if (type == OPTION_IP)
247 dest += sprint_nip(dest, "/", option + 4);
249 // case OPTION_BOOLEAN:
250 // dest += sprintf(dest, *option ? "yes" : "no");
253 dest += sprintf(dest, "%u", *option);
258 move_from_unaligned16(val_u16, option);
259 dest += sprintf(dest, "%u", ntohs(val_u16));
265 move_from_unaligned32(val_u32, option);
266 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
269 /* Note: options which use 'return' instead of 'break'
270 * (for example, OPTION_STRING) skip the code which handles
271 * the case of list of options.
274 case OPTION_STRING_HOST:
275 memcpy(dest, option, len);
277 //TODO: it appears option 15 DHCP_DOMAIN_NAME is often abused
278 //by DHCP admins to contain a space-separated list of domains,
279 //not one domain name (presumably, to work as list of search domains,
280 //instead of using proper option 119 DHCP_DOMAIN_SEARCH).
281 //Currently, good_hostname() balks on strings containing spaces.
282 //Do we need to allow it? Only for DHCP_DOMAIN_NAME option?
283 if (type == OPTION_STRING_HOST && !good_hostname(dest))
284 safe_strncpy(dest, "bad", len);
286 case OPTION_STATIC_ROUTES: {
287 /* Option binary format:
288 * mask [one byte, 0..32]
289 * ip [big endian, 0..4 bytes depending on mask]
290 * router [big endian, 4 bytes]
293 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
295 const char *pfx = "";
297 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
310 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
311 while (--bytes >= 0) {
319 dest += sprint_nip(dest, pfx, (void*) &nip);
321 dest += sprintf(dest, "/%u ", mask);
323 dest += sprint_nip(dest, "", option);
331 /* Option binary format (see RFC 5969):
333 * 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
334 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
335 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
336 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
338 * ... (16 octets) ...
339 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
340 * ... 6rdBRIPv4Address(es) ...
341 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
342 * We convert it to a string
343 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
345 * Sanity check: ensure that our length is at least 22 bytes, that
347 * 6rdPrefixLen <= 128,
348 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
349 * (2nd condition need no check - it follows from 1st and 3rd).
350 * Else, return envvar with empty value ("optname=")
352 if (len >= (1 + 1 + 16 + 4)
354 && (option[1] + 32 - option[0]) <= 128
357 dest += sprintf(dest, "%u ", *option++);
359 dest += sprintf(dest, "%u ", *option++);
361 dest += sprint_nip6(dest, /* "", */ option);
363 len -= 1 + 1 + 16 + 4;
364 /* "+ 4" above corresponds to the length of IPv4 addr
365 * we consume in the loop below */
367 /* 6rdBRIPv4Address(es) */
368 dest += sprint_nip(dest, " ", option);
370 len -= 4; /* do we have yet another 4+ bytes? */
377 #if ENABLE_FEATURE_UDHCP_RFC3397
378 case OPTION_DNS_STRING:
379 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
380 dest = dname_dec(option, len, ret);
385 /* error. return "optname=" string */
387 case OPTION_SIP_SERVERS:
388 /* Option binary format:
390 * type=0: domain names, dns-compressed
395 if (option[-1] == 0) {
396 dest = dname_dec(option, len, ret);
402 if (option[-1] == 1) {
403 const char *pfx = "";
408 dest += sprint_nip(dest, pfx, option);
417 /* If we are here, try to format any remaining data
418 * in the option as another, similarly-formatted option
422 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
423 // Should we bail out/warn if we see multi-ip option which is
424 // not allowed to be such (for example, DHCP_BROADCAST)? -
425 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
434 /* put all the parameters into the environment */
435 static char **fill_envp(struct dhcp_packet *packet)
440 const char *opt_name;
442 uint8_t overload = 0;
444 #define BITMAP unsigned
445 #define BBITS (sizeof(BITMAP) * 8)
446 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
447 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
448 BITMAP found_opts[256 / BBITS];
450 memset(found_opts, 0, sizeof(found_opts));
452 /* We need 6 elements for:
454 * "ip=N.N.N.N" from packet->yiaddr
455 * "siaddr=IP" from packet->siaddr_nip (unless 0)
456 * "boot_file=FILE" from packet->file (unless overloaded)
457 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
461 /* +1 element for each option, +2 for subnet option: */
463 /* note: do not search for "pad" (0) and "end" (255) options */
464 //TODO: change logic to scan packet _once_
465 for (i = 1; i < 255; i++) {
466 temp = udhcp_get_option(packet, i);
468 if (i == DHCP_OPTION_OVERLOAD)
470 else if (i == DHCP_SUBNET)
471 envc++; /* for $mask */
473 /*if (i != DHCP_MESSAGE_TYPE)*/
474 FOUND_OPTS(i) |= BMASK(i);
478 curr = envp = xzalloc(sizeof(envp[0]) * envc);
480 *curr = xasprintf("interface=%s", client_config.interface);
486 /* Export BOOTP fields. Fields we don't (yet?) export:
487 * uint8_t op; // always BOOTREPLY
488 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
489 * uint8_t hlen; // hardware address length
490 * uint8_t hops; // used by relay agents only
492 * uint16_t secs; // elapsed since client began acquisition/renewal
493 * uint16_t flags; // only one flag so far: bcast. Never set by server
494 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
495 * // if during renew server wants to give us different IP?)
496 * uint32_t gateway_nip; // relay agent IP address
497 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
498 * TODO: export gateway_nip as $giaddr?
500 /* Most important one: yiaddr as $ip */
501 *curr = xmalloc(sizeof("ip=255.255.255.255"));
502 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
504 if (packet->siaddr_nip) {
505 /* IP address of next server to use in bootstrap */
506 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
507 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
510 if (!(overload & FILE_FIELD) && packet->file[0]) {
511 /* watch out for invalid packets */
512 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
515 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
516 /* watch out for invalid packets */
517 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
521 /* Export known DHCP options */
522 opt_name = dhcp_option_strings;
525 uint8_t code = dhcp_optflags[i].code;
526 BITMAP *found_ptr = &FOUND_OPTS(code);
527 BITMAP found_mask = BMASK(code);
528 if (!(*found_ptr & found_mask))
530 *found_ptr &= ~found_mask; /* leave only unknown options */
531 temp = udhcp_get_option(packet, code);
532 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
534 if (code == DHCP_SUBNET) {
535 /* Subnet option: make things like "$ip/$mask" possible */
537 move_from_unaligned32(subnet, temp);
538 *curr = xasprintf("mask=%u", mton(subnet));
542 opt_name += strlen(opt_name) + 1;
545 /* Export unknown options */
546 for (i = 0; i < 256;) {
547 BITMAP bitmap = FOUND_OPTS(i);
552 if (bitmap & BMASK(i)) {
555 temp = udhcp_get_option(packet, i);
556 /* udhcp_get_option returns ptr to data portion,
557 * need to go back to get len
559 len = temp[-OPT_DATA + OPT_LEN];
560 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
561 ofs = sprintf(*curr, "opt%u=", i);
562 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
571 /* Call a script with a par file and env vars */
572 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
577 envp = fill_envp(packet);
580 log1("executing %s %s", client_config.script, name);
581 argv[0] = (char*) client_config.script;
582 argv[1] = (char*) name;
584 spawn_and_wait(argv);
586 for (curr = envp; *curr; curr++) {
588 bb_unsetenv_and_free(*curr);
594 /*** Sending/receiving packets ***/
596 static ALWAYS_INLINE uint32_t random_xid(void)
601 /* Initialize the packet with the proper defaults */
602 static void init_packet(struct dhcp_packet *packet, char type)
606 /* Fill in: op, htype, hlen, cookie fields; message type option: */
607 udhcp_init_header(packet, type);
609 packet->xid = random_xid();
611 client_config.last_secs = monotonic_sec();
612 if (client_config.first_secs == 0)
613 client_config.first_secs = client_config.last_secs;
614 secs = client_config.last_secs - client_config.first_secs;
615 packet->secs = htons(secs);
617 memcpy(packet->chaddr, client_config.client_mac, 6);
618 if (client_config.clientid)
619 udhcp_add_binary_option(packet, client_config.clientid);
622 static void add_client_options(struct dhcp_packet *packet)
626 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
628 /* Add a "param req" option with the list of options we'd like to have
629 * from stubborn DHCP servers. Pull the data from the struct in common.c.
630 * No bounds checking because it goes towards the head of the packet. */
631 end = udhcp_end_option(packet->options);
633 for (i = 1; i < DHCP_END; i++) {
634 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
635 packet->options[end + OPT_DATA + len] = i;
640 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
641 packet->options[end + OPT_LEN] = len;
642 packet->options[end + OPT_DATA + len] = DHCP_END;
645 if (client_config.vendorclass)
646 udhcp_add_binary_option(packet, client_config.vendorclass);
647 if (client_config.hostname)
648 udhcp_add_binary_option(packet, client_config.hostname);
649 if (client_config.fqdn)
650 udhcp_add_binary_option(packet, client_config.fqdn);
652 /* Request broadcast replies if we have no IP addr */
653 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
654 packet->flags |= htons(BROADCAST_FLAG);
656 /* Add -x options if any */
658 struct option_set *curr = client_config.options;
660 udhcp_add_binary_option(packet, curr->data);
663 // if (client_config.sname)
664 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
665 // if (client_config.boot_file)
666 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
669 // This will be needed if we remove -V VENDOR_STR in favor of
670 // -x vendor:VENDOR_STR
671 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
672 // /* not set, set the default vendor ID */
673 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
677 * 4.4.4 Use of broadcast and unicast
679 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
680 * messages, unless the client knows the address of a DHCP server.
681 * The client unicasts DHCPRELEASE messages to the server. Because
682 * the client is declining the use of the IP address supplied by the server,
683 * the client broadcasts DHCPDECLINE messages.
685 * When the DHCP client knows the address of a DHCP server, in either
686 * INIT or REBOOTING state, the client may use that address
687 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
688 * The client may also use unicast to send DHCPINFORM messages
689 * to a known DHCP server. If the client receives no response to DHCP
690 * messages sent to the IP address of a known DHCP server, the DHCP
691 * client reverts to using the IP broadcast address.
694 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet, uint32_t src_nip)
696 return udhcp_send_raw_packet(packet,
697 /*src*/ src_nip, CLIENT_PORT,
698 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
699 client_config.ifindex);
702 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
705 return udhcp_send_kernel_packet(packet,
707 server, SERVER_PORT);
708 return raw_bcast_from_client_config_ifindex(packet, ciaddr);
711 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
712 /* NOINLINE: limit stack usage in caller */
713 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
715 struct dhcp_packet packet;
717 /* Fill in: op, htype, hlen, cookie, chaddr fields,
718 * random xid field (we override it below),
719 * client-id option (unless -C), message type option:
721 init_packet(&packet, DHCPDISCOVER);
725 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
727 /* Add options: maxsize,
728 * optionally: hostname, fqdn, vendorclass,
729 * "param req" option according to -O, options specified with -x
731 add_client_options(&packet);
733 bb_error_msg("sending %s", "discover");
734 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
737 /* Broadcast a DHCP request message */
738 /* RFC 2131 3.1 paragraph 3:
739 * "The client _broadcasts_ a DHCPREQUEST message..."
741 /* NOINLINE: limit stack usage in caller */
742 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
744 struct dhcp_packet packet;
745 struct in_addr temp_addr;
748 * RFC 2131 4.3.2 DHCPREQUEST message
750 * If the DHCPREQUEST message contains a 'server identifier'
751 * option, the message is in response to a DHCPOFFER message.
752 * Otherwise, the message is a request to verify or extend an
753 * existing lease. If the client uses a 'client identifier'
754 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
755 * in all subsequent messages. If the client included a list
756 * of requested parameters in a DHCPDISCOVER message, it MUST
757 * include that list in all subsequent messages.
759 /* Fill in: op, htype, hlen, cookie, chaddr fields,
760 * random xid field (we override it below),
761 * client-id option (unless -C), message type option:
763 init_packet(&packet, DHCPREQUEST);
766 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
768 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
770 /* Add options: maxsize,
771 * optionally: hostname, fqdn, vendorclass,
772 * "param req" option according to -O, and options specified with -x
774 add_client_options(&packet);
776 temp_addr.s_addr = requested;
777 bb_error_msg("sending select for %s", inet_ntoa(temp_addr));
778 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
781 /* Unicast or broadcast a DHCP renew message */
782 /* NOINLINE: limit stack usage in caller */
783 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
785 struct dhcp_packet packet;
786 struct in_addr temp_addr;
789 * RFC 2131 4.3.2 DHCPREQUEST message
791 * DHCPREQUEST generated during RENEWING state:
793 * 'server identifier' MUST NOT be filled in, 'requested IP address'
794 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
795 * client's IP address. In this situation, the client is completely
796 * configured, and is trying to extend its lease. This message will
797 * be unicast, so no relay agents will be involved in its
798 * transmission. Because 'giaddr' is therefore not filled in, the
799 * DHCP server will trust the value in 'ciaddr', and use it when
800 * replying to the client.
802 /* Fill in: op, htype, hlen, cookie, chaddr fields,
803 * random xid field (we override it below),
804 * client-id option (unless -C), message type option:
806 init_packet(&packet, DHCPREQUEST);
809 packet.ciaddr = ciaddr;
811 /* Add options: maxsize,
812 * optionally: hostname, fqdn, vendorclass,
813 * "param req" option according to -O, and options specified with -x
815 add_client_options(&packet);
817 temp_addr.s_addr = server;
818 bb_error_msg("sending renew to %s", inet_ntoa(temp_addr));
819 return bcast_or_ucast(&packet, ciaddr, server);
822 #if ENABLE_FEATURE_UDHCPC_ARPING
823 /* Broadcast a DHCP decline message */
824 /* NOINLINE: limit stack usage in caller */
825 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
827 struct dhcp_packet packet;
829 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
830 * client-id option (unless -C), message type option:
832 init_packet(&packet, DHCPDECLINE);
835 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
836 * but in case the server is buggy and wants DHCPDECLINE's xid
837 * to match the xid which started entire handshake,
838 * we use the same xid we used in initial DHCPDISCOVER:
842 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
843 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
845 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
847 bb_error_msg("sending %s", "decline");
848 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
852 /* Unicast a DHCP release message */
854 ALWAYS_INLINE /* one caller, help compiler to use this fact */
855 int send_release(uint32_t server, uint32_t ciaddr)
857 struct dhcp_packet packet;
859 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
860 * client-id option (unless -C), message type option:
862 init_packet(&packet, DHCPRELEASE);
864 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
865 packet.ciaddr = ciaddr;
867 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
869 bb_error_msg("sending %s", "release");
870 /* Note: normally we unicast here since "server" is not zero.
871 * However, there _are_ people who run "address-less" DHCP servers,
872 * and reportedly ISC dhcp client and Windows allow that.
874 return bcast_or_ucast(&packet, ciaddr, server);
877 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
878 /* NOINLINE: limit stack usage in caller */
879 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
882 struct ip_udp_dhcp_packet packet;
884 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
887 struct cmsghdr *cmsg;
889 /* used to use just safe_read(fd, &packet, sizeof(packet))
890 * but we need to check for TP_STATUS_CSUMNOTREADY :(
892 iov.iov_base = &packet;
893 iov.iov_len = sizeof(packet);
894 memset(&msg, 0, sizeof(msg));
897 msg.msg_control = cmsgbuf;
898 msg.msg_controllen = sizeof(cmsgbuf);
900 bytes = recvmsg(fd, &msg, 0);
904 log1("packet read error, ignoring");
905 /* NB: possible down interface, etc. Caller should pause. */
906 return bytes; /* returns -1 */
911 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
912 log1("packet is too short, ignoring");
916 if (bytes < ntohs(packet.ip.tot_len)) {
917 /* packet is bigger than sizeof(packet), we did partial read */
918 log1("oversized packet, ignoring");
922 /* ignore any extra garbage bytes */
923 bytes = ntohs(packet.ip.tot_len);
925 /* make sure its the right packet for us, and that it passes sanity checks */
926 if (packet.ip.protocol != IPPROTO_UDP
927 || packet.ip.version != IPVERSION
928 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
929 || packet.udp.dest != htons(CLIENT_PORT)
930 /* || bytes > (int) sizeof(packet) - can't happen */
931 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
933 log1("unrelated/bogus packet, ignoring");
937 /* verify IP checksum */
938 check = packet.ip.check;
940 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
941 log1("bad IP header checksum, ignoring");
945 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
946 if (cmsg->cmsg_level == SOL_PACKET
947 && cmsg->cmsg_type == PACKET_AUXDATA
949 /* some VMs don't checksum UDP and TCP data
950 * they send to the same physical machine,
951 * here we detect this case:
953 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
954 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
955 goto skip_udp_sum_check;
959 /* verify UDP checksum. IP header has to be modified for this */
960 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
961 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
962 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
963 check = packet.udp.check;
964 packet.udp.check = 0;
965 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
966 log1("packet with bad UDP checksum received, ignoring");
971 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
972 bb_error_msg("packet with bad magic, ignoring");
976 log1("received %s", "a packet");
977 udhcp_dump_packet(&packet.data);
979 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
980 memcpy(dhcp_pkt, &packet.data, bytes);
987 static int sockfd = -1;
989 #define LISTEN_NONE 0
990 #define LISTEN_KERNEL 1
992 static smallint listen_mode;
994 /* initial state: (re)start DHCP negotiation */
995 #define INIT_SELECTING 0
996 /* discover was sent, DHCPOFFER reply received */
998 /* select/renew was sent, DHCPACK reply received */
1000 /* half of lease passed, want to renew it by sending unicast renew requests */
1002 /* renew requests were not answered, lease is almost over, send broadcast renew */
1004 /* manually requested renew (SIGUSR1) */
1005 #define RENEW_REQUESTED 5
1006 /* release, possibly manually requested (SIGUSR2) */
1008 static smallint state;
1010 static int udhcp_raw_socket(int ifindex)
1013 struct sockaddr_ll sock;
1015 log2("opening raw socket on ifindex %d", ifindex);
1017 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
1019 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
1020 * ETH_P_IP: want to receive only packets with IPv4 eth type
1022 log2("got raw socket fd");
1024 memset(&sock, 0, sizeof(sock)); /* let's be deterministic */
1025 sock.sll_family = AF_PACKET;
1026 sock.sll_protocol = htons(ETH_P_IP);
1027 sock.sll_ifindex = ifindex;
1028 /*sock.sll_hatype = ARPHRD_???;*/
1029 /*sock.sll_pkttype = PACKET_???;*/
1030 /*sock.sll_halen = ???;*/
1031 /*sock.sll_addr[8] = ???;*/
1032 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1034 #if 0 /* Several users reported breakage when BPF filter is used */
1035 if (CLIENT_PORT == 68) {
1036 /* Use only if standard port is in use */
1038 * I've selected not to see LL header, so BPF doesn't see it, too.
1039 * The filter may also pass non-IP and non-ARP packets, but we do
1040 * a more complete check when receiving the message in userspace.
1042 * and filter shamelessly stolen from:
1044 * http://www.flamewarmaster.de/software/dhcpclient/
1046 * There are a few other interesting ideas on that page (look under
1047 * "Motivation"). Use of netlink events is most interesting. Think
1048 * of various network servers listening for events and reconfiguring.
1049 * That would obsolete sending HUP signals and/or make use of restarts.
1051 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1054 static const struct sock_filter filter_instr[] = {
1055 /* load 9th byte (protocol) */
1056 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1057 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1058 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1059 /* L1: load halfword from offset 6 (flags and frag offset) */
1060 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1061 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1062 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1063 /* L2: skip IP header (load index reg with header len) */
1064 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1065 /* load udp destination port from halfword[header_len + 2] */
1066 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1067 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1068 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1069 /* L3: accept packet ("accept 0x7fffffff bytes") */
1070 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1071 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1072 /* L4: discard packet ("accept zero bytes") */
1073 BPF_STMT(BPF_RET|BPF_K, 0),
1075 static const struct sock_fprog filter_prog = {
1076 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1077 /* casting const away: */
1078 .filter = (struct sock_filter *) filter_instr,
1080 /* Ignoring error (kernel may lack support for this) */
1081 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1082 sizeof(filter_prog)) >= 0)
1083 log1("attached filter to raw socket fd"); // log?
1087 if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1088 if (errno != ENOPROTOOPT)
1089 log1("can't set PACKET_AUXDATA on raw socket");
1092 log1("created raw socket");
1097 static void change_listen_mode(int new_mode)
1099 log1("entering listen mode: %s",
1100 new_mode != LISTEN_NONE
1101 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1105 listen_mode = new_mode;
1110 if (new_mode == LISTEN_KERNEL)
1111 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1112 else if (new_mode != LISTEN_NONE)
1113 sockfd = udhcp_raw_socket(client_config.ifindex);
1114 /* else LISTEN_NONE: sockfd stays closed */
1117 /* Called only on SIGUSR1 */
1118 static void perform_renew(void)
1120 bb_error_msg("performing DHCP renew");
1123 change_listen_mode(LISTEN_KERNEL);
1126 state = RENEW_REQUESTED;
1128 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1129 udhcp_run_script(NULL, "deconfig");
1132 change_listen_mode(LISTEN_RAW);
1133 state = INIT_SELECTING;
1135 case INIT_SELECTING:
1140 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1142 char buffer[sizeof("255.255.255.255")];
1143 struct in_addr temp_addr;
1145 /* send release packet */
1147 || state == RENEWING
1148 || state == REBINDING
1149 || state == RENEW_REQUESTED
1151 temp_addr.s_addr = server_addr;
1152 strcpy(buffer, inet_ntoa(temp_addr));
1153 temp_addr.s_addr = requested_ip;
1154 bb_error_msg("unicasting a release of %s to %s",
1155 inet_ntoa(temp_addr), buffer);
1156 send_release(server_addr, requested_ip); /* unicast */
1158 bb_error_msg("entering released state");
1160 * We can be here on: SIGUSR2,
1161 * or on exit (SIGTERM) and -R "release on quit" is specified.
1162 * Users requested to be notified in all cases, even if not in one
1163 * of the states above.
1165 udhcp_run_script(NULL, "deconfig");
1167 change_listen_mode(LISTEN_NONE);
1171 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1174 int len = strnlen(str, 255);
1175 storage = xzalloc(len + extra + OPT_DATA);
1176 storage[OPT_CODE] = code;
1177 storage[OPT_LEN] = len + extra;
1178 memcpy(storage + extra + OPT_DATA, str, len);
1183 static void client_background(void)
1186 logmode &= ~LOGMODE_STDIO;
1187 /* rewrite pidfile, as our pid is different now */
1188 write_pidfile(client_config.pidfile);
1192 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1193 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1195 //usage:# define IF_UDHCP_VERBOSE(...)
1197 //usage:#define udhcpc_trivial_usage
1198 //usage: "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1199 //usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1200 //usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1201 //usage:#define udhcpc_full_usage "\n"
1202 //usage: "\n -i IFACE Interface to use (default eth0)"
1203 //usage: IF_FEATURE_UDHCP_PORT(
1204 //usage: "\n -P PORT Use PORT (default 68)"
1206 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1207 //usage: "\n -p FILE Create pidfile"
1208 //usage: "\n -B Request broadcast replies"
1209 //usage: "\n -t N Send up to N discover packets (default 3)"
1210 //usage: "\n -T SEC Pause between packets (default 3)"
1211 //usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1212 //usage: "\n -n Exit if lease is not obtained"
1213 //usage: "\n -q Exit after obtaining lease"
1214 //usage: "\n -R Release IP on exit"
1215 //usage: "\n -f Run in foreground"
1216 //usage: USE_FOR_MMU(
1217 //usage: "\n -b Background if lease is not obtained"
1219 //usage: "\n -S Log to syslog too"
1220 //usage: IF_FEATURE_UDHCPC_ARPING(
1221 //usage: "\n -a[MSEC] Validate offered address with ARP ping"
1223 //usage: "\n -r IP Request this IP address"
1224 //usage: "\n -o Don't request any options (unless -O is given)"
1225 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1226 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1227 //usage: "\n Examples of string, numeric, and hex byte opts:"
1228 //usage: "\n -x hostname:bbox - option 12"
1229 //usage: "\n -x lease:3600 - option 51 (lease time)"
1230 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1231 //usage: "\n -x 14:'\"dumpfile\"' - option 14 (shell-quoted)"
1232 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1233 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1234 //usage: "\n -C Don't send MAC as client identifier"
1235 //usage: IF_UDHCP_VERBOSE(
1236 //usage: "\n -v Verbose"
1238 //usage: "\nSignals:"
1239 //usage: "\n USR1 Renew lease"
1240 //usage: "\n USR2 Release lease"
1243 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1244 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1247 const char *str_V, *str_h, *str_F, *str_r;
1248 IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1249 IF_FEATURE_UDHCP_PORT(char *str_P;)
1250 void *clientid_mac_ptr;
1251 llist_t *list_O = NULL;
1252 llist_t *list_x = NULL;
1253 int tryagain_timeout = 20;
1254 int discover_timeout = 3;
1255 int discover_retries = 3;
1256 uint32_t server_addr = server_addr; /* for compiler */
1257 uint32_t requested_ip = 0;
1258 uint32_t xid = xid; /* for compiler */
1260 int timeout; /* must be signed */
1261 unsigned already_waited_sec;
1263 IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1266 setup_common_bufsiz();
1268 /* Default options */
1269 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1270 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1271 client_config.interface = "eth0";
1272 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1273 str_V = "udhcp "BB_VER;
1275 /* Parse command line */
1276 opt = getopt32long(argv, "^"
1277 /* O,x: list; -T,-t,-A take numeric param */
1278 "CV:H:h:F:i:np:qRr:s:T:+t:+SA:+O:*ox:*fB"
1280 IF_FEATURE_UDHCPC_ARPING("a::")
1281 IF_FEATURE_UDHCP_PORT("P:")
1283 "\0" IF_UDHCP_VERBOSE("vv") /* -v is a counter */
1285 , &str_V, &str_h, &str_h, &str_F
1286 , &client_config.interface, &client_config.pidfile /* i,p */
1288 , &client_config.script /* s */
1289 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1292 IF_FEATURE_UDHCPC_ARPING(, &str_a)
1293 IF_FEATURE_UDHCP_PORT(, &str_P)
1294 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1296 if (opt & (OPT_h|OPT_H)) {
1298 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1299 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1302 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1303 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1304 /* Flag bits: 0000NEOS
1305 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1306 * O: 1 = Server indicates to client that DNS has been updated regardless
1307 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1308 * not "host.domain.com". Format 0 is obsolete.
1309 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1310 * Two [0] bytes which follow are deprecated and must be 0.
1312 client_config.fqdn[OPT_DATA + 0] = 0x1;
1313 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1314 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1317 requested_ip = inet_addr(str_r);
1318 #if ENABLE_FEATURE_UDHCP_PORT
1320 CLIENT_PORT = xatou16(str_P);
1321 SERVER_PORT = CLIENT_PORT - 1;
1324 IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1326 char *optstr = llist_pop(&list_O);
1327 unsigned n = bb_strtou(optstr, NULL, 0);
1328 if (errno || n > 254) {
1329 n = udhcp_option_idx(optstr, dhcp_option_strings);
1330 n = dhcp_optflags[n].code;
1332 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1334 if (!(opt & OPT_o)) {
1336 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1337 if (dhcp_optflags[i].flags & OPTION_REQ) {
1338 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1343 char *optstr = xstrdup(llist_pop(&list_x));
1344 udhcp_str2optset(optstr, &client_config.options,
1345 dhcp_optflags, dhcp_option_strings,
1351 if (udhcp_read_interface(client_config.interface,
1352 &client_config.ifindex,
1354 client_config.client_mac)
1359 clientid_mac_ptr = NULL;
1360 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1361 /* not suppressed and not set, set the default client ID */
1362 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1363 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1364 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1365 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1367 if (str_V[0] != '\0') {
1368 // can drop -V, str_V, client_config.vendorclass,
1369 // but need to add "vendor" to the list of recognized
1370 // string opts for this to work;
1371 // and need to tweak add_client_options() too...
1372 // ...so the question is, should we?
1373 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1374 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1378 /* on NOMMU reexec (i.e., background) early */
1379 if (!(opt & OPT_f)) {
1380 bb_daemonize_or_rexec(0 /* flags */, argv);
1381 logmode = LOGMODE_NONE;
1385 openlog(applet_name, LOG_PID, LOG_DAEMON);
1386 logmode |= LOGMODE_SYSLOG;
1389 /* Make sure fd 0,1,2 are open */
1390 bb_sanitize_stdio();
1391 /* Create pidfile */
1392 write_pidfile(client_config.pidfile);
1393 /* Goes to stdout (unless NOMMU) and possibly syslog */
1394 bb_error_msg("started, v"BB_VER);
1395 /* Set up the signal pipe */
1397 /* We want random_xid to be random... */
1398 srand(monotonic_us());
1400 state = INIT_SELECTING;
1401 udhcp_run_script(NULL, "deconfig");
1402 change_listen_mode(LISTEN_RAW);
1405 already_waited_sec = 0;
1407 /* Main event loop. select() waits on signal pipe and possibly
1409 * "continue" statements in code below jump to the top of the loop.
1413 struct pollfd pfds[2];
1414 struct dhcp_packet packet;
1415 /* silence "uninitialized!" warning */
1416 unsigned timestamp_before_wait = timestamp_before_wait;
1418 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1420 /* Was opening raw or udp socket here
1421 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1422 * but on fast network renew responses return faster
1423 * than we open sockets. Thus this code is moved
1424 * to change_listen_mode(). Thus we open listen socket
1425 * BEFORE we send renew request (see "case BOUND:"). */
1427 udhcp_sp_fd_set(pfds, sockfd);
1429 tv = timeout - already_waited_sec;
1431 /* If we already timed out, fall through with retval = 0, else... */
1433 log1("waiting %u seconds", tv);
1434 timestamp_before_wait = (unsigned)monotonic_sec();
1435 retval = poll(pfds, 2, tv < INT_MAX/1000 ? tv * 1000 : INT_MAX);
1437 /* EINTR? A signal was caught, don't panic */
1438 if (errno == EINTR) {
1439 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1442 /* Else: an error occurred, panic! */
1443 bb_perror_msg_and_die("poll");
1447 /* If timeout dropped to zero, time to become active:
1448 * resend discover/renew/whatever
1451 /* When running on a bridge, the ifindex may have changed
1452 * (e.g. if member interfaces were added/removed
1453 * or if the status of the bridge changed).
1454 * Refresh ifindex and client_mac:
1456 if (udhcp_read_interface(client_config.interface,
1457 &client_config.ifindex,
1459 client_config.client_mac)
1461 goto ret0; /* iface is gone? */
1463 if (clientid_mac_ptr)
1464 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1466 /* We will restart the wait in any case */
1467 already_waited_sec = 0;
1470 case INIT_SELECTING:
1471 if (!discover_retries || packet_num < discover_retries) {
1472 if (packet_num == 0)
1475 send_discover(xid, requested_ip);
1476 timeout = discover_timeout;
1481 udhcp_run_script(NULL, "leasefail");
1482 #if BB_MMU /* -b is not supported on NOMMU */
1483 if (opt & OPT_b) { /* background if no lease */
1484 bb_error_msg("no lease, forking to background");
1485 client_background();
1486 /* do not background again! */
1487 opt = ((opt & ~OPT_b) | OPT_f);
1490 if (opt & OPT_n) { /* abort if no lease */
1491 bb_error_msg("no lease, failing");
1495 /* wait before trying again */
1496 timeout = tryagain_timeout;
1500 if (packet_num < 3) {
1501 /* send broadcast select packet */
1502 send_select(xid, server_addr, requested_ip);
1503 timeout = discover_timeout;
1507 /* Timed out, go back to init state.
1508 * "discover...select...discover..." loops
1509 * were seen in the wild. Treat them similarly
1510 * to "no response to discover" case */
1511 change_listen_mode(LISTEN_RAW);
1512 state = INIT_SELECTING;
1515 /* 1/2 lease passed, enter renewing state */
1517 client_config.first_secs = 0; /* make secs field count from 0 */
1518 change_listen_mode(LISTEN_KERNEL);
1519 log1("entering renew state");
1520 /* fall right through */
1521 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1522 case_RENEW_REQUESTED:
1524 if (timeout >= 60) {
1525 /* send an unicast renew request */
1526 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1527 * a new UDP socket for sending inside send_renew.
1528 * I hazard to guess existing listening socket
1529 * is somehow conflicting with it, but why is it
1530 * not deterministic then?! Strange.
1531 * Anyway, it does recover by eventually failing through
1532 * into INIT_SELECTING state.
1534 if (send_renew(xid, server_addr, requested_ip) >= 0) {
1536 //TODO: the timeout to receive an answer for our renew should not be selected
1537 //with "timeout = lease_seconds / 2; ...; timeout = timeout / 2": it is often huge.
1538 //Waiting e.g. 4*3600 seconds for a reply does not make sense
1539 //(if reply isn't coming, we keep an open socket for hours),
1540 //it should be something like 10 seconds.
1541 //Also, it's probably best to try sending renew in kernel mode a few (3-5) times
1542 //and fall back to raw mode if it does not work.
1545 /* else: error sending.
1546 * example: ENETUNREACH seen with server
1547 * which gave us bogus server ID 1.1.1.1
1548 * which wasn't reachable (and probably did not exist).
1551 /* Timed out or error, enter rebinding state */
1552 log1("entering rebinding state");
1554 /* fall right through */
1556 /* Switch to bcast receive */
1557 change_listen_mode(LISTEN_RAW);
1558 /* Lease is *really* about to run out,
1559 * try to find DHCP server using broadcast */
1561 /* send a broadcast renew request */
1562 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1566 /* Timed out, enter init state */
1567 bb_error_msg("lease lost, entering init state");
1568 udhcp_run_script(NULL, "deconfig");
1569 state = INIT_SELECTING;
1570 client_config.first_secs = 0; /* make secs field count from 0 */
1571 /*timeout = 0; - already is */
1574 /* case RELEASED: */
1576 /* yah, I know, *you* say it would never happen */
1578 continue; /* back to main loop */
1579 } /* if poll timed out */
1581 /* poll() didn't timeout, something happened */
1583 /* Is it a signal? */
1584 switch (udhcp_sp_read()) {
1586 client_config.first_secs = 0; /* make secs field count from 0 */
1587 already_waited_sec = 0;
1589 if (state == RENEW_REQUESTED) {
1590 /* We might be either on the same network
1591 * (in which case renew might work),
1592 * or we might be on a completely different one
1593 * (in which case renew won't ever succeed).
1594 * For the second case, must make sure timeout
1595 * is not too big, or else we can send
1596 * futile renew requests for hours.
1600 goto case_RENEW_REQUESTED;
1602 /* Start things over */
1604 /* Kill any timeouts, user wants this to hurry along */
1608 perform_release(server_addr, requested_ip);
1612 bb_error_msg("received %s", "SIGTERM");
1616 /* Is it a packet? */
1617 if (!pfds[1].revents)
1623 /* A packet is ready, read it */
1624 if (listen_mode == LISTEN_KERNEL)
1625 len = udhcp_recv_kernel_packet(&packet, sockfd);
1627 len = udhcp_recv_raw_packet(&packet, sockfd);
1629 /* Error is severe, reopen socket */
1630 bb_error_msg("read error: "STRERROR_FMT", reopening socket" STRERROR_ERRNO);
1631 sleep(discover_timeout); /* 3 seconds by default */
1632 change_listen_mode(listen_mode); /* just close and reopen */
1634 /* If this packet will turn out to be unrelated/bogus,
1635 * we will go back and wait for next one.
1636 * Be sure timeout is properly decreased. */
1637 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1642 if (packet.xid != xid) {
1643 log1("xid %x (our is %x), ignoring packet",
1644 (unsigned)packet.xid, (unsigned)xid);
1648 /* Ignore packets that aren't for us */
1649 if (packet.hlen != 6
1650 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1652 //FIXME: need to also check that last 10 bytes are zero
1653 log1("chaddr does not match, ignoring packet"); // log2?
1657 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1658 if (message == NULL) {
1659 bb_error_msg("no message type option, ignoring packet");
1664 case INIT_SELECTING:
1665 /* Must be a DHCPOFFER */
1666 if (*message == DHCPOFFER) {
1669 /* What exactly is server's IP? There are several values.
1670 * Example DHCP offer captured with tchdump:
1672 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1674 * Your-IP 10.34.25.202
1675 * Server-IP 10.34.32.125 // "next server" IP
1676 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1678 * DHCP-Message Option 53, length 1: Offer
1679 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1680 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1682 * We think that real server IP (one to use in renew/release)
1683 * is one in Server-ID option. But I am not 100% sure.
1684 * IP header's src and Gateway-IP (same in this example)
1686 * "Next server" and router are definitely wrong ones to use, though...
1688 /* We used to ignore pcakets without DHCP_SERVER_ID.
1689 * I've got user reports from people who run "address-less" servers.
1690 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1691 * They say ISC DHCP client supports this case.
1694 temp = udhcp_get_option32(&packet, DHCP_SERVER_ID);
1696 bb_error_msg("no server ID, using 0.0.0.0");
1698 /* it IS unaligned sometimes, don't "optimize" */
1699 move_from_unaligned32(server_addr, temp);
1701 /*xid = packet.xid; - already is */
1702 requested_ip = packet.yiaddr;
1704 /* enter requesting state */
1708 already_waited_sec = 0;
1713 case RENEW_REQUESTED:
1715 if (*message == DHCPACK) {
1717 uint32_t lease_seconds;
1718 struct in_addr temp_addr;
1721 temp = udhcp_get_option32(&packet, DHCP_LEASE_TIME);
1723 bb_error_msg("no lease time with ACK, using 1 hour lease");
1724 lease_seconds = 60 * 60;
1726 /* it IS unaligned sometimes, don't "optimize" */
1727 move_from_unaligned32(lease_seconds, temp);
1728 lease_seconds = ntohl(lease_seconds);
1729 /* paranoia: must not be too small and not prone to overflows */
1730 /* timeout > 60 - ensures at least one unicast renew attempt */
1731 if (lease_seconds < 2 * 61)
1732 lease_seconds = 2 * 61;
1733 //if (lease_seconds > 0x7fffffff)
1734 // lease_seconds = 0x7fffffff;
1735 //^^^not necessary since "timeout = lease_seconds / 2"
1736 //does not overflow even for 0xffffffff.
1738 #if ENABLE_FEATURE_UDHCPC_ARPING
1740 /* RFC 2131 3.1 paragraph 5:
1741 * "The client receives the DHCPACK message with configuration
1742 * parameters. The client SHOULD perform a final check on the
1743 * parameters (e.g., ARP for allocated network address), and notes
1744 * the duration of the lease specified in the DHCPACK message. At this
1745 * point, the client is configured. If the client detects that the
1746 * address is already in use (e.g., through the use of ARP),
1747 * the client MUST send a DHCPDECLINE message to the server and restarts
1748 * the configuration process..." */
1749 if (!arpping(packet.yiaddr,
1752 client_config.client_mac,
1753 client_config.interface,
1756 bb_error_msg("offered address is in use "
1757 "(got ARP reply), declining");
1758 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1760 if (state != REQUESTING)
1761 udhcp_run_script(NULL, "deconfig");
1762 change_listen_mode(LISTEN_RAW);
1763 state = INIT_SELECTING;
1764 client_config.first_secs = 0; /* make secs field count from 0 */
1766 timeout = tryagain_timeout;
1768 already_waited_sec = 0;
1769 continue; /* back to main loop */
1773 /* enter bound state */
1774 temp_addr.s_addr = packet.yiaddr;
1775 bb_error_msg("lease of %s obtained, lease time %u",
1776 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1777 requested_ip = packet.yiaddr;
1779 start = monotonic_sec();
1780 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1781 already_waited_sec = (unsigned)monotonic_sec() - start;
1782 timeout = lease_seconds / 2;
1783 if ((unsigned)timeout < already_waited_sec) {
1784 /* Something went wrong. Back to discover state */
1785 timeout = already_waited_sec = 0;
1789 change_listen_mode(LISTEN_NONE);
1790 if (opt & OPT_q) { /* quit after lease */
1793 /* future renew failures should not exit (JM) */
1795 #if BB_MMU /* NOMMU case backgrounded earlier */
1796 if (!(opt & OPT_f)) {
1797 client_background();
1798 /* do not background again! */
1799 opt = ((opt & ~OPT_b) | OPT_f);
1802 /* make future renew packets use different xid */
1803 /* xid = random_xid(); ...but why bother? */
1805 continue; /* back to main loop */
1807 if (*message == DHCPNAK) {
1808 /* If network has more than one DHCP server,
1809 * "wrong" server can reply first, with a NAK.
1810 * Do not interpret it as a NAK from "our" server.
1812 if (server_addr != 0) {
1816 temp = udhcp_get_option32(&packet, DHCP_SERVER_ID);
1819 log1("received DHCP NAK with wrong"
1820 " server ID, ignoring packet");
1823 move_from_unaligned32(svid, temp);
1824 if (svid != server_addr)
1825 goto non_matching_svid;
1827 /* return to init state */
1828 bb_error_msg("received %s", "DHCP NAK");
1829 udhcp_run_script(&packet, "nak");
1830 if (state != REQUESTING)
1831 udhcp_run_script(NULL, "deconfig");
1832 change_listen_mode(LISTEN_RAW);
1833 sleep(3); /* avoid excessive network traffic */
1834 state = INIT_SELECTING;
1835 client_config.first_secs = 0; /* make secs field count from 0 */
1839 already_waited_sec = 0;
1842 /* case BOUND: - ignore all packets */
1843 /* case RELEASED: - ignore all packets */
1845 /* back to main loop */
1846 } /* for (;;) - main loop ends */
1849 if (opt & OPT_R) /* release on quit */
1850 perform_release(server_addr, requested_ip);
1853 /*if (client_config.pidfile) - remove_pidfile has its own check */
1854 remove_pidfile(client_config.pidfile);