1 /* vi: set sw=4 ts=4: */
5 * Russ Dill <Russ.Dill@asu.edu> July 2001
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License as published by
9 * the Free Software Foundation; either version 2 of the License, or
10 * (at your option) any later version.
12 * This program is distributed in the hope that it will be useful,
13 * but WITHOUT ANY WARRANTY; without even the implied warranty of
14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 * GNU General Public License for more details.
17 * You should have received a copy of the GNU General Public License
18 * along with this program; if not, write to the Free Software
19 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
22 /* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
23 #define WANT_PIDFILE 1
28 #include <netinet/if_ether.h>
29 #include <linux/filter.h>
30 #include <linux/if_packet.h>
32 #ifndef PACKET_AUXDATA
33 # define PACKET_AUXDATA 8
34 struct tpacket_auxdata {
46 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
50 static const char udhcpc_longopts[] ALIGN1 =
51 "clientid-none\0" No_argument "C"
52 "vendorclass\0" Required_argument "V"
53 "hostname\0" Required_argument "H"
54 "fqdn\0" Required_argument "F"
55 "interface\0" Required_argument "i"
56 "now\0" No_argument "n"
57 "pidfile\0" Required_argument "p"
58 "quit\0" No_argument "q"
59 "release\0" No_argument "R"
60 "request\0" Required_argument "r"
61 "script\0" Required_argument "s"
62 "timeout\0" Required_argument "T"
63 "retries\0" Required_argument "t"
64 "tryagain\0" Required_argument "A"
65 "syslog\0" No_argument "S"
66 "request-option\0" Required_argument "O"
67 "no-default-options\0" No_argument "o"
68 "foreground\0" No_argument "f"
69 "background\0" No_argument "b"
70 "broadcast\0" No_argument "B"
71 IF_FEATURE_UDHCPC_ARPING("arping\0" Optional_argument "a")
72 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
75 /* Must match getopt32 option string order */
98 /* The rest has variable bit positions, need to be clever */
100 USE_FOR_MMU( OPTBIT_b,)
101 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
102 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
103 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
104 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
105 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
109 /*** Script execution code ***/
111 /* get a rough idea of how long an option will be (rounding up...) */
112 static const uint8_t len_of_option_as_string[] = {
113 [OPTION_IP ] = sizeof("255.255.255.255 "),
114 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
115 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
116 [OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
117 [OPTION_STRING ] = 1,
118 [OPTION_STRING_HOST ] = 1,
119 #if ENABLE_FEATURE_UDHCP_RFC3397
120 [OPTION_DNS_STRING ] = 1, /* unused */
121 /* Hmmm, this severely overestimates size if SIP_SERVERS option
122 * is in domain name form: N-byte option in binary form
123 * mallocs ~16*N bytes. But it is freed almost at once.
125 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
127 // [OPTION_BOOLEAN ] = sizeof("yes "),
128 [OPTION_U8 ] = sizeof("255 "),
129 [OPTION_U16 ] = sizeof("65535 "),
130 // [OPTION_S16 ] = sizeof("-32768 "),
131 [OPTION_U32 ] = sizeof("4294967295 "),
132 [OPTION_S32 ] = sizeof("-2147483684 "),
135 /* note: ip is a pointer to an IP in network order, possibly misaliged */
136 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
138 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
141 /* really simple implementation, just count the bits */
142 static int mton(uint32_t mask)
145 mask = ntohl(mask); /* 111110000-like bit pattern */
153 #if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
154 /* Check if a given label represents a valid DNS label
155 * Return pointer to the first character after the label upon success,
159 /* We don't need to be particularly anal. For example, allowing _, hyphen
160 * at the end, or leading and trailing dots would be ok, since it
161 * can't be used for attacks. (Leading hyphen can be, if someone uses
163 * in the script: then hostname may be treated as an option)
165 static const char *valid_domain_label(const char *label)
172 if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
173 if (ch < '0' || ch > '9') {
174 if (ch == '\0' || ch == '.')
176 /* DNS allows only '-', but we are more permissive */
177 if (ch != '-' && ch != '_')
184 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
189 /* Check if a given name represents a valid DNS name */
190 /* See RFC1035, 2.3.1 */
191 static int good_hostname(const char *name)
193 //const char *start = name;
196 name = valid_domain_label(name);
202 //return ((name - start) < 1025); /* NS_MAXDNAME */
207 # define good_hostname(name) 1
210 /* Create "opt_name=opt_value" string */
211 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
213 unsigned upper_length;
214 int len, type, optlen;
217 /* option points to OPT_DATA, need to go back to get OPT_LEN */
218 len = option[-OPT_DATA + OPT_LEN];
220 type = optflag->flags & OPTION_TYPE_MASK;
221 optlen = dhcp_option_lengths[type];
222 upper_length = len_of_option_as_string[type]
223 * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
225 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
226 dest += sprintf(ret, "%s=", opt_name);
228 while (len >= optlen) {
232 dest += sprint_nip(dest, "", option);
233 if (type == OPTION_IP)
235 dest += sprint_nip(dest, "/", option + 4);
237 // case OPTION_BOOLEAN:
238 // dest += sprintf(dest, *option ? "yes" : "no");
241 dest += sprintf(dest, "%u", *option);
246 move_from_unaligned16(val_u16, option);
247 dest += sprintf(dest, "%u", ntohs(val_u16));
253 move_from_unaligned32(val_u32, option);
254 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
257 /* Note: options which use 'return' instead of 'break'
258 * (for example, OPTION_STRING) skip the code which handles
259 * the case of list of options.
262 case OPTION_STRING_HOST:
263 memcpy(dest, option, len);
265 if (type == OPTION_STRING_HOST && !good_hostname(dest))
266 safe_strncpy(dest, "bad", len);
268 case OPTION_STATIC_ROUTES: {
269 /* Option binary format:
270 * mask [one byte, 0..32]
271 * ip [big endian, 0..4 bytes depending on mask]
272 * router [big endian, 4 bytes]
275 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
277 const char *pfx = "";
279 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
292 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
293 while (--bytes >= 0) {
301 dest += sprint_nip(dest, pfx, (void*) &nip);
303 dest += sprintf(dest, "/%u ", mask);
305 dest += sprint_nip(dest, "", option);
313 /* Option binary format (see RFC 5969):
315 * 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
316 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
317 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
318 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
320 * ... (16 octets) ...
321 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
322 * ... 6rdBRIPv4Address(es) ...
323 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
324 * We convert it to a string
325 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
327 * Sanity check: ensure that our length is at least 22 bytes, that
329 * 6rdPrefixLen <= 128,
330 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
331 * (2nd condition need no check - it follows from 1st and 3rd).
332 * Else, return envvar with empty value ("optname=")
334 if (len >= (1 + 1 + 16 + 4)
336 && (option[1] + 32 - option[0]) <= 128
339 dest += sprintf(dest, "%u ", *option++);
341 dest += sprintf(dest, "%u ", *option++);
343 dest += sprint_nip6(dest, /* "", */ option);
345 len -= 1 + 1 + 16 + 4;
346 /* "+ 4" above corresponds to the length of IPv4 addr
347 * we consume in the loop below */
349 /* 6rdBRIPv4Address(es) */
350 dest += sprint_nip(dest, " ", option);
352 len -= 4; /* do we have yet another 4+ bytes? */
359 #if ENABLE_FEATURE_UDHCP_RFC3397
360 case OPTION_DNS_STRING:
361 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
362 dest = dname_dec(option, len, ret);
367 /* error. return "optname=" string */
369 case OPTION_SIP_SERVERS:
370 /* Option binary format:
372 * type=0: domain names, dns-compressed
377 if (option[-1] == 0) {
378 dest = dname_dec(option, len, ret);
384 if (option[-1] == 1) {
385 const char *pfx = "";
390 dest += sprint_nip(dest, pfx, option);
399 /* If we are here, try to format any remaining data
400 * in the option as another, similarly-formatted option
404 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
405 // Should we bail out/warn if we see multi-ip option which is
406 // not allowed to be such (for example, DHCP_BROADCAST)? -
407 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
416 /* put all the parameters into the environment */
417 static char **fill_envp(struct dhcp_packet *packet)
422 const char *opt_name;
424 uint8_t overload = 0;
426 #define BITMAP unsigned
427 #define BBITS (sizeof(BITMAP) * 8)
428 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
429 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
430 BITMAP found_opts[256 / BBITS];
432 memset(found_opts, 0, sizeof(found_opts));
434 /* We need 6 elements for:
436 * "ip=N.N.N.N" from packet->yiaddr
437 * "siaddr=IP" from packet->siaddr_nip (unless 0)
438 * "boot_file=FILE" from packet->file (unless overloaded)
439 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
443 /* +1 element for each option, +2 for subnet option: */
445 /* note: do not search for "pad" (0) and "end" (255) options */
446 //TODO: change logic to scan packet _once_
447 for (i = 1; i < 255; i++) {
448 temp = udhcp_get_option(packet, i);
450 if (i == DHCP_OPTION_OVERLOAD)
452 else if (i == DHCP_SUBNET)
453 envc++; /* for $mask */
455 /*if (i != DHCP_MESSAGE_TYPE)*/
456 FOUND_OPTS(i) |= BMASK(i);
460 curr = envp = xzalloc(sizeof(envp[0]) * envc);
462 *curr = xasprintf("interface=%s", client_config.interface);
468 /* Export BOOTP fields. Fields we don't (yet?) export:
469 * uint8_t op; // always BOOTREPLY
470 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
471 * uint8_t hlen; // hardware address length
472 * uint8_t hops; // used by relay agents only
474 * uint16_t secs; // elapsed since client began acquisition/renewal
475 * uint16_t flags; // only one flag so far: bcast. Never set by server
476 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
477 * // if during renew server wants to give us differn IP?)
478 * uint32_t gateway_nip; // relay agent IP address
479 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
480 * TODO: export gateway_nip as $giaddr?
482 /* Most important one: yiaddr as $ip */
483 *curr = xmalloc(sizeof("ip=255.255.255.255"));
484 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
486 if (packet->siaddr_nip) {
487 /* IP address of next server to use in bootstrap */
488 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
489 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
492 if (!(overload & FILE_FIELD) && packet->file[0]) {
493 /* watch out for invalid packets */
494 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
497 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
498 /* watch out for invalid packets */
499 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
503 /* Export known DHCP options */
504 opt_name = dhcp_option_strings;
507 uint8_t code = dhcp_optflags[i].code;
508 BITMAP *found_ptr = &FOUND_OPTS(code);
509 BITMAP found_mask = BMASK(code);
510 if (!(*found_ptr & found_mask))
512 *found_ptr &= ~found_mask; /* leave only unknown options */
513 temp = udhcp_get_option(packet, code);
514 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
516 if (code == DHCP_SUBNET) {
517 /* Subnet option: make things like "$ip/$mask" possible */
519 move_from_unaligned32(subnet, temp);
520 *curr = xasprintf("mask=%u", mton(subnet));
524 opt_name += strlen(opt_name) + 1;
527 /* Export unknown options */
528 for (i = 0; i < 256;) {
529 BITMAP bitmap = FOUND_OPTS(i);
534 if (bitmap & BMASK(i)) {
537 temp = udhcp_get_option(packet, i);
538 /* udhcp_get_option returns ptr to data portion,
539 * need to go back to get len
541 len = temp[-OPT_DATA + OPT_LEN];
542 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
543 ofs = sprintf(*curr, "opt%u=", i);
544 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
553 /* Call a script with a par file and env vars */
554 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
559 envp = fill_envp(packet);
562 log1("Executing %s %s", client_config.script, name);
563 argv[0] = (char*) client_config.script;
564 argv[1] = (char*) name;
566 spawn_and_wait(argv);
568 for (curr = envp; *curr; curr++) {
570 bb_unsetenv_and_free(*curr);
576 /*** Sending/receiving packets ***/
578 static ALWAYS_INLINE uint32_t random_xid(void)
583 /* Initialize the packet with the proper defaults */
584 static void init_packet(struct dhcp_packet *packet, char type)
588 /* Fill in: op, htype, hlen, cookie fields; message type option: */
589 udhcp_init_header(packet, type);
591 packet->xid = random_xid();
593 client_config.last_secs = monotonic_sec();
594 if (client_config.first_secs == 0)
595 client_config.first_secs = client_config.last_secs;
596 secs = client_config.last_secs - client_config.first_secs;
597 packet->secs = htons(secs);
599 memcpy(packet->chaddr, client_config.client_mac, 6);
600 if (client_config.clientid)
601 udhcp_add_binary_option(packet, client_config.clientid);
604 static void add_client_options(struct dhcp_packet *packet)
608 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
610 /* Add a "param req" option with the list of options we'd like to have
611 * from stubborn DHCP servers. Pull the data from the struct in common.c.
612 * No bounds checking because it goes towards the head of the packet. */
613 end = udhcp_end_option(packet->options);
615 for (i = 1; i < DHCP_END; i++) {
616 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
617 packet->options[end + OPT_DATA + len] = i;
622 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
623 packet->options[end + OPT_LEN] = len;
624 packet->options[end + OPT_DATA + len] = DHCP_END;
627 if (client_config.vendorclass)
628 udhcp_add_binary_option(packet, client_config.vendorclass);
629 if (client_config.hostname)
630 udhcp_add_binary_option(packet, client_config.hostname);
631 if (client_config.fqdn)
632 udhcp_add_binary_option(packet, client_config.fqdn);
634 /* Request broadcast replies if we have no IP addr */
635 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
636 packet->flags |= htons(BROADCAST_FLAG);
638 /* Add -x options if any */
640 struct option_set *curr = client_config.options;
642 udhcp_add_binary_option(packet, curr->data);
645 // if (client_config.sname)
646 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
647 // if (client_config.boot_file)
648 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
651 // This will be needed if we remove -V VENDOR_STR in favor of
652 // -x vendor:VENDOR_STR
653 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
654 // /* not set, set the default vendor ID */
655 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
659 * 4.4.4 Use of broadcast and unicast
661 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
662 * messages, unless the client knows the address of a DHCP server.
663 * The client unicasts DHCPRELEASE messages to the server. Because
664 * the client is declining the use of the IP address supplied by the server,
665 * the client broadcasts DHCPDECLINE messages.
667 * When the DHCP client knows the address of a DHCP server, in either
668 * INIT or REBOOTING state, the client may use that address
669 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
670 * The client may also use unicast to send DHCPINFORM messages
671 * to a known DHCP server. If the client receives no response to DHCP
672 * messages sent to the IP address of a known DHCP server, the DHCP
673 * client reverts to using the IP broadcast address.
676 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
678 return udhcp_send_raw_packet(packet,
679 /*src*/ INADDR_ANY, CLIENT_PORT,
680 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
681 client_config.ifindex);
684 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
687 return udhcp_send_kernel_packet(packet,
689 server, SERVER_PORT);
690 return raw_bcast_from_client_config_ifindex(packet);
693 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
694 /* NOINLINE: limit stack usage in caller */
695 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
697 struct dhcp_packet packet;
699 /* Fill in: op, htype, hlen, cookie, chaddr fields,
700 * random xid field (we override it below),
701 * client-id option (unless -C), message type option:
703 init_packet(&packet, DHCPDISCOVER);
707 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
709 /* Add options: maxsize,
710 * optionally: hostname, fqdn, vendorclass,
711 * "param req" option according to -O, options specified with -x
713 add_client_options(&packet);
715 bb_info_msg("Sending discover...");
716 return raw_bcast_from_client_config_ifindex(&packet);
719 /* Broadcast a DHCP request message */
720 /* RFC 2131 3.1 paragraph 3:
721 * "The client _broadcasts_ a DHCPREQUEST message..."
723 /* NOINLINE: limit stack usage in caller */
724 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
726 struct dhcp_packet packet;
730 * RFC 2131 4.3.2 DHCPREQUEST message
732 * If the DHCPREQUEST message contains a 'server identifier'
733 * option, the message is in response to a DHCPOFFER message.
734 * Otherwise, the message is a request to verify or extend an
735 * existing lease. If the client uses a 'client identifier'
736 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
737 * in all subsequent messages. If the client included a list
738 * of requested parameters in a DHCPDISCOVER message, it MUST
739 * include that list in all subsequent messages.
741 /* Fill in: op, htype, hlen, cookie, chaddr fields,
742 * random xid field (we override it below),
743 * client-id option (unless -C), message type option:
745 init_packet(&packet, DHCPREQUEST);
748 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
750 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
752 /* Add options: maxsize,
753 * optionally: hostname, fqdn, vendorclass,
754 * "param req" option according to -O, and options specified with -x
756 add_client_options(&packet);
758 addr.s_addr = requested;
759 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
760 return raw_bcast_from_client_config_ifindex(&packet);
763 /* Unicast or broadcast a DHCP renew message */
764 /* NOINLINE: limit stack usage in caller */
765 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
767 struct dhcp_packet packet;
770 * RFC 2131 4.3.2 DHCPREQUEST message
772 * DHCPREQUEST generated during RENEWING state:
774 * 'server identifier' MUST NOT be filled in, 'requested IP address'
775 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
776 * client's IP address. In this situation, the client is completely
777 * configured, and is trying to extend its lease. This message will
778 * be unicast, so no relay agents will be involved in its
779 * transmission. Because 'giaddr' is therefore not filled in, the
780 * DHCP server will trust the value in 'ciaddr', and use it when
781 * replying to the client.
783 /* Fill in: op, htype, hlen, cookie, chaddr fields,
784 * random xid field (we override it below),
785 * client-id option (unless -C), message type option:
787 init_packet(&packet, DHCPREQUEST);
790 packet.ciaddr = ciaddr;
792 /* Add options: maxsize,
793 * optionally: hostname, fqdn, vendorclass,
794 * "param req" option according to -O, and options specified with -x
796 add_client_options(&packet);
798 bb_info_msg("Sending renew...");
799 return bcast_or_ucast(&packet, ciaddr, server);
802 #if ENABLE_FEATURE_UDHCPC_ARPING
803 /* Broadcast a DHCP decline message */
804 /* NOINLINE: limit stack usage in caller */
805 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
807 struct dhcp_packet packet;
809 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
810 * client-id option (unless -C), message type option:
812 init_packet(&packet, DHCPDECLINE);
815 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
816 * but in case the server is buggy and wants DHCPDECLINE's xid
817 * to match the xid which started entire handshake,
818 * we use the same xid we used in initial DHCPDISCOVER:
822 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
823 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
825 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
827 bb_info_msg("Sending decline...");
828 return raw_bcast_from_client_config_ifindex(&packet);
832 /* Unicast a DHCP release message */
833 static int send_release(uint32_t server, uint32_t ciaddr)
835 struct dhcp_packet packet;
837 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
838 * client-id option (unless -C), message type option:
840 init_packet(&packet, DHCPRELEASE);
842 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
843 packet.ciaddr = ciaddr;
845 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
847 bb_info_msg("Sending release...");
848 /* Note: normally we unicast here since "server" is not zero.
849 * However, there _are_ people who run "address-less" DHCP servers,
850 * and reportedly ISC dhcp client and Windows allow that.
852 return bcast_or_ucast(&packet, ciaddr, server);
855 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
856 /* NOINLINE: limit stack usage in caller */
857 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
860 struct ip_udp_dhcp_packet packet;
862 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
865 struct cmsghdr *cmsg;
867 /* used to use just safe_read(fd, &packet, sizeof(packet))
868 * but we need to check for TP_STATUS_CSUMNOTREADY :(
870 iov.iov_base = &packet;
871 iov.iov_len = sizeof(packet);
872 memset(&msg, 0, sizeof(msg));
875 msg.msg_control = cmsgbuf;
876 msg.msg_controllen = sizeof(cmsgbuf);
878 bytes = recvmsg(fd, &msg, 0);
882 log1("Packet read error, ignoring");
883 /* NB: possible down interface, etc. Caller should pause. */
884 return bytes; /* returns -1 */
889 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
890 log1("Packet is too short, ignoring");
894 if (bytes < ntohs(packet.ip.tot_len)) {
895 /* packet is bigger than sizeof(packet), we did partial read */
896 log1("Oversized packet, ignoring");
900 /* ignore any extra garbage bytes */
901 bytes = ntohs(packet.ip.tot_len);
903 /* make sure its the right packet for us, and that it passes sanity checks */
904 if (packet.ip.protocol != IPPROTO_UDP
905 || packet.ip.version != IPVERSION
906 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
907 || packet.udp.dest != htons(CLIENT_PORT)
908 /* || bytes > (int) sizeof(packet) - can't happen */
909 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
911 log1("Unrelated/bogus packet, ignoring");
915 /* verify IP checksum */
916 check = packet.ip.check;
918 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
919 log1("Bad IP header checksum, ignoring");
923 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
924 if (cmsg->cmsg_level == SOL_PACKET
925 && cmsg->cmsg_type == PACKET_AUXDATA
927 /* some VMs don't checksum UDP and TCP data
928 * they send to the same physical machine,
929 * here we detect this case:
931 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
932 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
933 goto skip_udp_sum_check;
937 /* verify UDP checksum. IP header has to be modified for this */
938 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
939 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
940 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
941 check = packet.udp.check;
942 packet.udp.check = 0;
943 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
944 log1("Packet with bad UDP checksum received, ignoring");
949 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
950 bb_info_msg("Packet with bad magic, ignoring");
954 log1("Received a packet");
955 udhcp_dump_packet(&packet.data);
957 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
958 memcpy(dhcp_pkt, &packet.data, bytes);
965 static int sockfd = -1;
967 #define LISTEN_NONE 0
968 #define LISTEN_KERNEL 1
970 static smallint listen_mode;
972 /* initial state: (re)start DHCP negotiation */
973 #define INIT_SELECTING 0
974 /* discover was sent, DHCPOFFER reply received */
976 /* select/renew was sent, DHCPACK reply received */
978 /* half of lease passed, want to renew it by sending unicast renew requests */
980 /* renew requests were not answered, lease is almost over, send broadcast renew */
982 /* manually requested renew (SIGUSR1) */
983 #define RENEW_REQUESTED 5
984 /* release, possibly manually requested (SIGUSR2) */
986 static smallint state;
988 static int udhcp_raw_socket(int ifindex)
991 struct sockaddr_ll sock;
993 log1("Opening raw socket on ifindex %d", ifindex); //log2?
995 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
997 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
998 * ETH_P_IP: want to receive only packets with IPv4 eth type
1000 log1("Got raw socket fd"); //log2?
1002 sock.sll_family = AF_PACKET;
1003 sock.sll_protocol = htons(ETH_P_IP);
1004 sock.sll_ifindex = ifindex;
1005 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1007 #if 0 /* Several users reported breakage when BPF filter is used */
1008 if (CLIENT_PORT == 68) {
1009 /* Use only if standard port is in use */
1011 * I've selected not to see LL header, so BPF doesn't see it, too.
1012 * The filter may also pass non-IP and non-ARP packets, but we do
1013 * a more complete check when receiving the message in userspace.
1015 * and filter shamelessly stolen from:
1017 * http://www.flamewarmaster.de/software/dhcpclient/
1019 * There are a few other interesting ideas on that page (look under
1020 * "Motivation"). Use of netlink events is most interesting. Think
1021 * of various network servers listening for events and reconfiguring.
1022 * That would obsolete sending HUP signals and/or make use of restarts.
1024 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1027 static const struct sock_filter filter_instr[] = {
1028 /* load 9th byte (protocol) */
1029 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1030 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1031 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1032 /* L1: load halfword from offset 6 (flags and frag offset) */
1033 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1034 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1035 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1036 /* L2: skip IP header (load index reg with header len) */
1037 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1038 /* load udp destination port from halfword[header_len + 2] */
1039 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1040 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1041 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1042 /* L3: accept packet ("accept 0x7fffffff bytes") */
1043 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1044 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1045 /* L4: discard packet ("accept zero bytes") */
1046 BPF_STMT(BPF_RET|BPF_K, 0),
1048 static const struct sock_fprog filter_prog = {
1049 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1050 /* casting const away: */
1051 .filter = (struct sock_filter *) filter_instr,
1053 /* Ignoring error (kernel may lack support for this) */
1054 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1055 sizeof(filter_prog)) >= 0)
1056 log1("Attached filter to raw socket fd"); // log?
1060 if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1061 if (errno != ENOPROTOOPT)
1062 log1("Can't set PACKET_AUXDATA on raw socket");
1065 log1("Created raw socket");
1070 static void change_listen_mode(int new_mode)
1072 log1("Entering listen mode: %s",
1073 new_mode != LISTEN_NONE
1074 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1078 listen_mode = new_mode;
1083 if (new_mode == LISTEN_KERNEL)
1084 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1085 else if (new_mode != LISTEN_NONE)
1086 sockfd = udhcp_raw_socket(client_config.ifindex);
1087 /* else LISTEN_NONE: sockfd stays closed */
1090 /* Called only on SIGUSR1 */
1091 static void perform_renew(void)
1093 bb_info_msg("Performing a DHCP renew");
1096 change_listen_mode(LISTEN_KERNEL);
1099 state = RENEW_REQUESTED;
1101 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1102 udhcp_run_script(NULL, "deconfig");
1105 change_listen_mode(LISTEN_RAW);
1106 state = INIT_SELECTING;
1108 case INIT_SELECTING:
1113 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1115 char buffer[sizeof("255.255.255.255")];
1116 struct in_addr temp_addr;
1118 /* send release packet */
1119 if (state == BOUND || state == RENEWING || state == REBINDING) {
1120 temp_addr.s_addr = server_addr;
1121 strcpy(buffer, inet_ntoa(temp_addr));
1122 temp_addr.s_addr = requested_ip;
1123 bb_info_msg("Unicasting a release of %s to %s",
1124 inet_ntoa(temp_addr), buffer);
1125 send_release(server_addr, requested_ip); /* unicast */
1126 udhcp_run_script(NULL, "deconfig");
1128 bb_info_msg("Entering released state");
1130 change_listen_mode(LISTEN_NONE);
1134 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1137 int len = strnlen(str, 255);
1138 storage = xzalloc(len + extra + OPT_DATA);
1139 storage[OPT_CODE] = code;
1140 storage[OPT_LEN] = len + extra;
1141 memcpy(storage + extra + OPT_DATA, str, len);
1146 static void client_background(void)
1149 logmode &= ~LOGMODE_STDIO;
1150 /* rewrite pidfile, as our pid is different now */
1151 write_pidfile(client_config.pidfile);
1155 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1156 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1158 //usage:# define IF_UDHCP_VERBOSE(...)
1160 //usage:#define udhcpc_trivial_usage
1161 //usage: "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1162 //usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1163 //usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1164 //usage:#define udhcpc_full_usage "\n"
1165 //usage: IF_LONG_OPTS(
1166 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1167 //usage: IF_FEATURE_UDHCP_PORT(
1168 //usage: "\n -P,--client-port PORT Use PORT (default 68)"
1170 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1171 //usage: "\n -p,--pidfile FILE Create pidfile"
1172 //usage: "\n -B,--broadcast Request broadcast replies"
1173 //usage: "\n -t,--retries N Send up to N discover packets (default 3)"
1174 //usage: "\n -T,--timeout SEC Pause between packets (default 3)"
1175 //usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
1176 //usage: "\n -n,--now Exit if lease is not obtained"
1177 //usage: "\n -q,--quit Exit after obtaining lease"
1178 //usage: "\n -R,--release Release IP on exit"
1179 //usage: "\n -f,--foreground Run in foreground"
1180 //usage: USE_FOR_MMU(
1181 //usage: "\n -b,--background Background if lease is not obtained"
1183 //usage: "\n -S,--syslog Log to syslog too"
1184 //usage: IF_FEATURE_UDHCPC_ARPING(
1185 //usage: "\n -a[MSEC],--arping[=MSEC] Validate offered address with ARP ping"
1187 //usage: "\n -r,--request IP Request this IP address"
1188 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1189 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1190 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1191 //usage: "\n Examples of string, numeric, and hex byte opts:"
1192 //usage: "\n -x hostname:bbox - option 12"
1193 //usage: "\n -x lease:3600 - option 51 (lease time)"
1194 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1195 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1196 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1197 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1198 //usage: IF_UDHCP_VERBOSE(
1199 //usage: "\n -v Verbose"
1202 //usage: IF_NOT_LONG_OPTS(
1203 //usage: "\n -i IFACE Interface to use (default eth0)"
1204 //usage: IF_FEATURE_UDHCP_PORT(
1205 //usage: "\n -P PORT Use PORT (default 68)"
1207 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1208 //usage: "\n -p FILE Create pidfile"
1209 //usage: "\n -B Request broadcast replies"
1210 //usage: "\n -t N Send up to N discover packets (default 3)"
1211 //usage: "\n -T SEC Pause between packets (default 3)"
1212 //usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1213 //usage: "\n -n Exit if lease is not obtained"
1214 //usage: "\n -q Exit after obtaining lease"
1215 //usage: "\n -R Release IP on exit"
1216 //usage: "\n -f Run in foreground"
1217 //usage: USE_FOR_MMU(
1218 //usage: "\n -b Background if lease is not obtained"
1220 //usage: "\n -S Log to syslog too"
1221 //usage: IF_FEATURE_UDHCPC_ARPING(
1222 //usage: "\n -a[MSEC] Validate offered address with ARP ping"
1224 //usage: "\n -r IP Request this IP address"
1225 //usage: "\n -o Don't request any options (unless -O is given)"
1226 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1227 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1228 //usage: "\n Examples of string, numeric, and hex byte opts:"
1229 //usage: "\n -x hostname:bbox - option 12"
1230 //usage: "\n -x lease:3600 - option 51 (lease time)"
1231 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
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"
1239 //usage: "\nSignals:"
1240 //usage: "\n USR1 Renew lease"
1241 //usage: "\n USR2 Release lease"
1244 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1245 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1248 const char *str_V, *str_h, *str_F, *str_r;
1249 IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1250 IF_FEATURE_UDHCP_PORT(char *str_P;)
1251 void *clientid_mac_ptr;
1252 llist_t *list_O = NULL;
1253 llist_t *list_x = NULL;
1254 int tryagain_timeout = 20;
1255 int discover_timeout = 3;
1256 int discover_retries = 3;
1257 uint32_t server_addr = server_addr; /* for compiler */
1258 uint32_t requested_ip = 0;
1259 uint32_t xid = xid; /* for compiler */
1261 int timeout; /* must be signed */
1262 unsigned already_waited_sec;
1264 IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1269 /* Default options */
1270 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1271 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1272 client_config.interface = "eth0";
1273 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1274 str_V = "udhcp "BB_VER;
1276 /* Parse command line */
1277 /* O,x: list; -T,-t,-A take numeric param */
1278 opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1279 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1280 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1282 IF_FEATURE_UDHCPC_ARPING("a::")
1283 IF_FEATURE_UDHCP_PORT("P:")
1285 , &str_V, &str_h, &str_h, &str_F
1286 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1287 , &client_config.script /* s */
1288 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1291 IF_FEATURE_UDHCPC_ARPING(, &str_a)
1292 IF_FEATURE_UDHCP_PORT(, &str_P)
1293 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1295 if (opt & (OPT_h|OPT_H)) {
1297 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1298 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1301 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1302 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1303 /* Flag bits: 0000NEOS
1304 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1305 * O: 1 = Server indicates to client that DNS has been updated regardless
1306 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1307 * not "host.domain.com". Format 0 is obsolete.
1308 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1309 * Two [0] bytes which follow are deprecated and must be 0.
1311 client_config.fqdn[OPT_DATA + 0] = 0x1;
1312 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1313 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1316 requested_ip = inet_addr(str_r);
1317 #if ENABLE_FEATURE_UDHCP_PORT
1319 CLIENT_PORT = xatou16(str_P);
1320 SERVER_PORT = CLIENT_PORT - 1;
1323 IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1325 char *optstr = llist_pop(&list_O);
1326 unsigned n = bb_strtou(optstr, NULL, 0);
1327 if (errno || n > 254) {
1328 n = udhcp_option_idx(optstr);
1329 n = dhcp_optflags[n].code;
1331 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1333 if (!(opt & OPT_o)) {
1335 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1336 if (dhcp_optflags[i].flags & OPTION_REQ) {
1337 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1342 char *optstr = llist_pop(&list_x);
1343 char *colon = strchr(optstr, ':');
1346 /* now it looks similar to udhcpd's config file line:
1347 * "optname optval", using the common routine: */
1348 udhcp_str2optset(optstr, &client_config.options);
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 /* Equivalent of doing a fflush after every \n */
1393 /* Create pidfile */
1394 write_pidfile(client_config.pidfile);
1395 /* Goes to stdout (unless NOMMU) and possibly syslog */
1396 bb_info_msg("%s (v"BB_VER") started", applet_name);
1397 /* Set up the signal pipe */
1399 /* We want random_xid to be random... */
1400 srand(monotonic_us());
1402 state = INIT_SELECTING;
1403 udhcp_run_script(NULL, "deconfig");
1404 change_listen_mode(LISTEN_RAW);
1407 already_waited_sec = 0;
1409 /* Main event loop. select() waits on signal pipe and possibly
1411 * "continue" statements in code below jump to the top of the loop.
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 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1430 tv.tv_sec = timeout - already_waited_sec;
1433 /* If we already timed out, fall through with retval = 0, else... */
1434 if ((int)tv.tv_sec > 0) {
1435 log1("Waiting on select %u seconds", (int)tv.tv_sec);
1436 timestamp_before_wait = (unsigned)monotonic_sec();
1437 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1439 /* EINTR? A signal was caught, don't panic */
1440 if (errno == EINTR) {
1441 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1444 /* Else: an error occured, panic! */
1445 bb_perror_msg_and_die("select");
1449 /* If timeout dropped to zero, time to become active:
1450 * resend discover/renew/whatever
1453 /* When running on a bridge, the ifindex may have changed
1454 * (e.g. if member interfaces were added/removed
1455 * or if the status of the bridge changed).
1456 * Refresh ifindex and client_mac:
1458 if (udhcp_read_interface(client_config.interface,
1459 &client_config.ifindex,
1461 client_config.client_mac)
1463 goto ret0; /* iface is gone? */
1465 if (clientid_mac_ptr)
1466 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1468 /* We will restart the wait in any case */
1469 already_waited_sec = 0;
1472 case INIT_SELECTING:
1473 if (!discover_retries || packet_num < discover_retries) {
1474 if (packet_num == 0)
1477 send_discover(xid, requested_ip);
1478 timeout = discover_timeout;
1483 udhcp_run_script(NULL, "leasefail");
1484 #if BB_MMU /* -b is not supported on NOMMU */
1485 if (opt & OPT_b) { /* background if no lease */
1486 bb_info_msg("No lease, forking to background");
1487 client_background();
1488 /* do not background again! */
1489 opt = ((opt & ~OPT_b) | OPT_f);
1492 if (opt & OPT_n) { /* abort if no lease */
1493 bb_info_msg("No lease, failing");
1497 /* wait before trying again */
1498 timeout = tryagain_timeout;
1502 if (!discover_retries || packet_num < discover_retries) {
1503 /* send broadcast select packet */
1504 send_select(xid, server_addr, requested_ip);
1505 timeout = discover_timeout;
1509 /* Timed out, go back to init state.
1510 * "discover...select...discover..." loops
1511 * were seen in the wild. Treat them similarly
1512 * to "no response to discover" case */
1513 change_listen_mode(LISTEN_RAW);
1514 state = INIT_SELECTING;
1517 /* 1/2 lease passed, enter renewing state */
1519 client_config.first_secs = 0; /* make secs field count from 0 */
1520 change_listen_mode(LISTEN_KERNEL);
1521 log1("Entering renew state");
1522 /* fall right through */
1523 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1524 case_RENEW_REQUESTED:
1527 /* send an unicast renew request */
1528 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1529 * a new UDP socket for sending inside send_renew.
1530 * I hazard to guess existing listening socket
1531 * is somehow conflicting with it, but why is it
1532 * not deterministic then?! Strange.
1533 * Anyway, it does recover by eventually failing through
1534 * into INIT_SELECTING state.
1536 send_renew(xid, server_addr, requested_ip);
1540 /* Timed out, enter rebinding state */
1541 log1("Entering rebinding state");
1543 /* fall right through */
1545 /* Switch to bcast receive */
1546 change_listen_mode(LISTEN_RAW);
1547 /* Lease is *really* about to run out,
1548 * try to find DHCP server using broadcast */
1550 /* send a broadcast renew request */
1551 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1555 /* Timed out, enter init state */
1556 bb_info_msg("Lease lost, entering init state");
1557 udhcp_run_script(NULL, "deconfig");
1558 state = INIT_SELECTING;
1559 client_config.first_secs = 0; /* make secs field count from 0 */
1560 /*timeout = 0; - already is */
1563 /* case RELEASED: */
1565 /* yah, I know, *you* say it would never happen */
1567 continue; /* back to main loop */
1568 } /* if select timed out */
1570 /* select() didn't timeout, something happened */
1572 /* Is it a signal? */
1573 /* note: udhcp_sp_read checks FD_ISSET before reading */
1574 switch (udhcp_sp_read(&rfds)) {
1576 client_config.first_secs = 0; /* make secs field count from 0 */
1577 already_waited_sec = 0;
1579 if (state == RENEW_REQUESTED) {
1580 /* We might be either on the same network
1581 * (in which case renew might work),
1582 * or we might be on a completely different one
1583 * (in which case renew won't ever succeed).
1584 * For the second case, must make sure timeout
1585 * is not too big, or else we can send
1586 * futile renew requests for hours.
1587 * (Ab)use -A TIMEOUT value (usually 20 sec)
1588 * as a cap on the timeout.
1590 if (timeout > tryagain_timeout)
1591 timeout = tryagain_timeout;
1592 goto case_RENEW_REQUESTED;
1594 /* Start things over */
1596 /* Kill any timeouts, user wants this to hurry along */
1600 perform_release(server_addr, requested_ip);
1604 bb_info_msg("Received SIGTERM");
1608 /* Is it a packet? */
1609 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1615 /* A packet is ready, read it */
1616 if (listen_mode == LISTEN_KERNEL)
1617 len = udhcp_recv_kernel_packet(&packet, sockfd);
1619 len = udhcp_recv_raw_packet(&packet, sockfd);
1621 /* Error is severe, reopen socket */
1622 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1623 sleep(discover_timeout); /* 3 seconds by default */
1624 change_listen_mode(listen_mode); /* just close and reopen */
1626 /* If this packet will turn out to be unrelated/bogus,
1627 * we will go back and wait for next one.
1628 * Be sure timeout is properly decreased. */
1629 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1634 if (packet.xid != xid) {
1635 log1("xid %x (our is %x), ignoring packet",
1636 (unsigned)packet.xid, (unsigned)xid);
1640 /* Ignore packets that aren't for us */
1641 if (packet.hlen != 6
1642 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1644 //FIXME: need to also check that last 10 bytes are zero
1645 log1("chaddr does not match, ignoring packet"); // log2?
1649 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1650 if (message == NULL) {
1651 bb_error_msg("no message type option, ignoring packet");
1656 case INIT_SELECTING:
1657 /* Must be a DHCPOFFER */
1658 if (*message == DHCPOFFER) {
1661 /* What exactly is server's IP? There are several values.
1662 * Example DHCP offer captured with tchdump:
1664 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1666 * Your-IP 10.34.25.202
1667 * Server-IP 10.34.32.125 // "next server" IP
1668 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1670 * DHCP-Message Option 53, length 1: Offer
1671 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1672 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1674 * We think that real server IP (one to use in renew/release)
1675 * is one in Server-ID option. But I am not 100% sure.
1676 * IP header's src and Gateway-IP (same in this example)
1678 * "Next server" and router are definitely wrong ones to use, though...
1680 /* We used to ignore pcakets without DHCP_SERVER_ID.
1681 * I've got user reports from people who run "address-less" servers.
1682 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1683 * They say ISC DHCP client supports this case.
1686 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1688 bb_error_msg("no server ID, using 0.0.0.0");
1690 /* it IS unaligned sometimes, don't "optimize" */
1691 move_from_unaligned32(server_addr, temp);
1693 /*xid = packet.xid; - already is */
1694 requested_ip = packet.yiaddr;
1696 /* enter requesting state */
1700 already_waited_sec = 0;
1705 case RENEW_REQUESTED:
1707 if (*message == DHCPACK) {
1709 uint32_t lease_seconds;
1710 struct in_addr temp_addr;
1713 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1715 bb_error_msg("no lease time with ACK, using 1 hour lease");
1716 lease_seconds = 60 * 60;
1718 /* it IS unaligned sometimes, don't "optimize" */
1719 move_from_unaligned32(lease_seconds, temp);
1720 lease_seconds = ntohl(lease_seconds);
1721 /* paranoia: must not be too small and not prone to overflows */
1722 if (lease_seconds < 0x10)
1723 lease_seconds = 0x10;
1724 if (lease_seconds >= 0x10000000)
1725 lease_seconds = 0x0fffffff;
1727 #if ENABLE_FEATURE_UDHCPC_ARPING
1729 /* RFC 2131 3.1 paragraph 5:
1730 * "The client receives the DHCPACK message with configuration
1731 * parameters. The client SHOULD perform a final check on the
1732 * parameters (e.g., ARP for allocated network address), and notes
1733 * the duration of the lease specified in the DHCPACK message. At this
1734 * point, the client is configured. If the client detects that the
1735 * address is already in use (e.g., through the use of ARP),
1736 * the client MUST send a DHCPDECLINE message to the server and restarts
1737 * the configuration process..." */
1738 if (!arpping(packet.yiaddr,
1741 client_config.client_mac,
1742 client_config.interface,
1745 bb_info_msg("Offered address is in use "
1746 "(got ARP reply), declining");
1747 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1749 if (state != REQUESTING)
1750 udhcp_run_script(NULL, "deconfig");
1751 change_listen_mode(LISTEN_RAW);
1752 state = INIT_SELECTING;
1753 client_config.first_secs = 0; /* make secs field count from 0 */
1755 timeout = tryagain_timeout;
1757 already_waited_sec = 0;
1758 continue; /* back to main loop */
1762 /* enter bound state */
1763 temp_addr.s_addr = packet.yiaddr;
1764 bb_info_msg("Lease of %s obtained, lease time %u",
1765 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1766 requested_ip = packet.yiaddr;
1768 start = monotonic_sec();
1769 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1770 already_waited_sec = (unsigned)monotonic_sec() - start;
1771 timeout = lease_seconds / 2;
1772 if ((unsigned)timeout < already_waited_sec) {
1773 /* Something went wrong. Back to discover state */
1774 timeout = already_waited_sec = 0;
1778 change_listen_mode(LISTEN_NONE);
1779 if (opt & OPT_q) { /* quit after lease */
1782 /* future renew failures should not exit (JM) */
1784 #if BB_MMU /* NOMMU case backgrounded earlier */
1785 if (!(opt & OPT_f)) {
1786 client_background();
1787 /* do not background again! */
1788 opt = ((opt & ~OPT_b) | OPT_f);
1791 /* make future renew packets use different xid */
1792 /* xid = random_xid(); ...but why bother? */
1794 continue; /* back to main loop */
1796 if (*message == DHCPNAK) {
1797 /* If network has more than one DHCP server,
1798 * "wrong" server can reply first, with a NAK.
1799 * Do not interpret it as a NAK from "our" server.
1801 if (server_addr != 0) {
1805 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1808 log1("%s with wrong server ID, ignoring packet",
1813 move_from_unaligned32(svid, temp);
1814 if (svid != server_addr)
1815 goto non_matching_svid;
1817 /* return to init state */
1818 bb_info_msg("Received DHCP NAK");
1819 udhcp_run_script(&packet, "nak");
1820 if (state != REQUESTING)
1821 udhcp_run_script(NULL, "deconfig");
1822 change_listen_mode(LISTEN_RAW);
1823 sleep(3); /* avoid excessive network traffic */
1824 state = INIT_SELECTING;
1825 client_config.first_secs = 0; /* make secs field count from 0 */
1829 already_waited_sec = 0;
1832 /* case BOUND: - ignore all packets */
1833 /* case RELEASED: - ignore all packets */
1835 /* back to main loop */
1836 } /* for (;;) - main loop ends */
1839 if (opt & OPT_R) /* release on quit */
1840 perform_release(server_addr, requested_ip);
1843 /*if (client_config.pidfile) - remove_pidfile has its own check */
1844 remove_pidfile(client_config.pidfile);