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[] ALIGN1 = {
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("132 128 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 */
205 return 1; // We allow trailing dot too
209 # define good_hostname(name) 1
212 /* Create "opt_name=opt_value" string */
213 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
215 unsigned upper_length;
216 int len, type, optlen;
219 /* option points to OPT_DATA, need to go back to get OPT_LEN */
220 len = option[-OPT_DATA + OPT_LEN];
222 type = optflag->flags & OPTION_TYPE_MASK;
223 optlen = dhcp_option_lengths[type];
224 upper_length = len_of_option_as_string[type]
225 * ((unsigned)(len + optlen) / (unsigned)optlen);
227 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
228 dest += sprintf(ret, "%s=", opt_name);
230 while (len >= optlen) {
234 dest += sprint_nip(dest, "", option);
235 if (type == OPTION_IP)
237 dest += sprint_nip(dest, "/", option + 4);
239 // case OPTION_BOOLEAN:
240 // dest += sprintf(dest, *option ? "yes" : "no");
243 dest += sprintf(dest, "%u", *option);
248 move_from_unaligned16(val_u16, option);
249 dest += sprintf(dest, "%u", ntohs(val_u16));
255 move_from_unaligned32(val_u32, option);
256 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
259 /* Note: options which use 'return' instead of 'break'
260 * (for example, OPTION_STRING) skip the code which handles
261 * the case of list of options.
264 case OPTION_STRING_HOST:
265 memcpy(dest, option, len);
267 if (type == OPTION_STRING_HOST && !good_hostname(dest))
268 safe_strncpy(dest, "bad", len);
270 case OPTION_STATIC_ROUTES: {
271 /* Option binary format:
272 * mask [one byte, 0..32]
273 * ip [big endian, 0..4 bytes depending on mask]
274 * router [big endian, 4 bytes]
277 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
279 const char *pfx = "";
281 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
294 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
295 while (--bytes >= 0) {
303 dest += sprint_nip(dest, pfx, (void*) &nip);
305 dest += sprintf(dest, "/%u ", mask);
307 dest += sprint_nip(dest, "", option);
315 /* Option binary format (see RFC 5969):
317 * 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
318 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
319 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
320 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
322 * ... (16 octets) ...
323 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
324 * ... 6rdBRIPv4Address(es) ...
325 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
326 * We convert it to a string
327 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
329 * Sanity check: ensure that our length is at least 22 bytes, that
331 * 6rdPrefixLen <= 128,
332 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
333 * (2nd condition need no check - it follows from 1st and 3rd).
334 * Else, return envvar with empty value ("optname=")
336 if (len >= (1 + 1 + 16 + 4)
338 && (option[1] + 32 - option[0]) <= 128
341 dest += sprintf(dest, "%u ", *option++);
343 dest += sprintf(dest, "%u ", *option++);
345 dest += sprint_nip6(dest, /* "", */ option);
347 len -= 1 + 1 + 16 + 4;
348 /* "+ 4" above corresponds to the length of IPv4 addr
349 * we consume in the loop below */
351 /* 6rdBRIPv4Address(es) */
352 dest += sprint_nip(dest, " ", option);
354 len -= 4; /* do we have yet another 4+ bytes? */
361 #if ENABLE_FEATURE_UDHCP_RFC3397
362 case OPTION_DNS_STRING:
363 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
364 dest = dname_dec(option, len, ret);
369 /* error. return "optname=" string */
371 case OPTION_SIP_SERVERS:
372 /* Option binary format:
374 * type=0: domain names, dns-compressed
379 if (option[-1] == 0) {
380 dest = dname_dec(option, len, ret);
386 if (option[-1] == 1) {
387 const char *pfx = "";
392 dest += sprint_nip(dest, pfx, option);
401 /* If we are here, try to format any remaining data
402 * in the option as another, similarly-formatted option
406 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
407 // Should we bail out/warn if we see multi-ip option which is
408 // not allowed to be such (for example, DHCP_BROADCAST)? -
409 if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
418 /* put all the parameters into the environment */
419 static char **fill_envp(struct dhcp_packet *packet)
424 const char *opt_name;
426 uint8_t overload = 0;
428 #define BITMAP unsigned
429 #define BBITS (sizeof(BITMAP) * 8)
430 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
431 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
432 BITMAP found_opts[256 / BBITS];
434 memset(found_opts, 0, sizeof(found_opts));
436 /* We need 6 elements for:
438 * "ip=N.N.N.N" from packet->yiaddr
439 * "siaddr=IP" from packet->siaddr_nip (unless 0)
440 * "boot_file=FILE" from packet->file (unless overloaded)
441 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
445 /* +1 element for each option, +2 for subnet option: */
447 /* note: do not search for "pad" (0) and "end" (255) options */
448 //TODO: change logic to scan packet _once_
449 for (i = 1; i < 255; i++) {
450 temp = udhcp_get_option(packet, i);
452 if (i == DHCP_OPTION_OVERLOAD)
454 else if (i == DHCP_SUBNET)
455 envc++; /* for $mask */
457 /*if (i != DHCP_MESSAGE_TYPE)*/
458 FOUND_OPTS(i) |= BMASK(i);
462 curr = envp = xzalloc(sizeof(envp[0]) * envc);
464 *curr = xasprintf("interface=%s", client_config.interface);
470 /* Export BOOTP fields. Fields we don't (yet?) export:
471 * uint8_t op; // always BOOTREPLY
472 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
473 * uint8_t hlen; // hardware address length
474 * uint8_t hops; // used by relay agents only
476 * uint16_t secs; // elapsed since client began acquisition/renewal
477 * uint16_t flags; // only one flag so far: bcast. Never set by server
478 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
479 * // if during renew server wants to give us differn IP?)
480 * uint32_t gateway_nip; // relay agent IP address
481 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
482 * TODO: export gateway_nip as $giaddr?
484 /* Most important one: yiaddr as $ip */
485 *curr = xmalloc(sizeof("ip=255.255.255.255"));
486 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
488 if (packet->siaddr_nip) {
489 /* IP address of next server to use in bootstrap */
490 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
491 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
494 if (!(overload & FILE_FIELD) && packet->file[0]) {
495 /* watch out for invalid packets */
496 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
499 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
500 /* watch out for invalid packets */
501 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
505 /* Export known DHCP options */
506 opt_name = dhcp_option_strings;
509 uint8_t code = dhcp_optflags[i].code;
510 BITMAP *found_ptr = &FOUND_OPTS(code);
511 BITMAP found_mask = BMASK(code);
512 if (!(*found_ptr & found_mask))
514 *found_ptr &= ~found_mask; /* leave only unknown options */
515 temp = udhcp_get_option(packet, code);
516 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
518 if (code == DHCP_SUBNET) {
519 /* Subnet option: make things like "$ip/$mask" possible */
521 move_from_unaligned32(subnet, temp);
522 *curr = xasprintf("mask=%u", mton(subnet));
526 opt_name += strlen(opt_name) + 1;
529 /* Export unknown options */
530 for (i = 0; i < 256;) {
531 BITMAP bitmap = FOUND_OPTS(i);
536 if (bitmap & BMASK(i)) {
539 temp = udhcp_get_option(packet, i);
540 /* udhcp_get_option returns ptr to data portion,
541 * need to go back to get len
543 len = temp[-OPT_DATA + OPT_LEN];
544 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
545 ofs = sprintf(*curr, "opt%u=", i);
546 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
555 /* Call a script with a par file and env vars */
556 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
561 envp = fill_envp(packet);
564 log1("executing %s %s", client_config.script, name);
565 argv[0] = (char*) client_config.script;
566 argv[1] = (char*) name;
568 spawn_and_wait(argv);
570 for (curr = envp; *curr; curr++) {
572 bb_unsetenv_and_free(*curr);
578 /*** Sending/receiving packets ***/
580 static ALWAYS_INLINE uint32_t random_xid(void)
585 /* Initialize the packet with the proper defaults */
586 static void init_packet(struct dhcp_packet *packet, char type)
590 /* Fill in: op, htype, hlen, cookie fields; message type option: */
591 udhcp_init_header(packet, type);
593 packet->xid = random_xid();
595 client_config.last_secs = monotonic_sec();
596 if (client_config.first_secs == 0)
597 client_config.first_secs = client_config.last_secs;
598 secs = client_config.last_secs - client_config.first_secs;
599 packet->secs = htons(secs);
601 memcpy(packet->chaddr, client_config.client_mac, 6);
602 if (client_config.clientid)
603 udhcp_add_binary_option(packet, client_config.clientid);
606 static void add_client_options(struct dhcp_packet *packet)
610 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
612 /* Add a "param req" option with the list of options we'd like to have
613 * from stubborn DHCP servers. Pull the data from the struct in common.c.
614 * No bounds checking because it goes towards the head of the packet. */
615 end = udhcp_end_option(packet->options);
617 for (i = 1; i < DHCP_END; i++) {
618 if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
619 packet->options[end + OPT_DATA + len] = i;
624 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
625 packet->options[end + OPT_LEN] = len;
626 packet->options[end + OPT_DATA + len] = DHCP_END;
629 if (client_config.vendorclass)
630 udhcp_add_binary_option(packet, client_config.vendorclass);
631 if (client_config.hostname)
632 udhcp_add_binary_option(packet, client_config.hostname);
633 if (client_config.fqdn)
634 udhcp_add_binary_option(packet, client_config.fqdn);
636 /* Request broadcast replies if we have no IP addr */
637 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
638 packet->flags |= htons(BROADCAST_FLAG);
640 /* Add -x options if any */
642 struct option_set *curr = client_config.options;
644 udhcp_add_binary_option(packet, curr->data);
647 // if (client_config.sname)
648 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
649 // if (client_config.boot_file)
650 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
653 // This will be needed if we remove -V VENDOR_STR in favor of
654 // -x vendor:VENDOR_STR
655 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
656 // /* not set, set the default vendor ID */
657 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
661 * 4.4.4 Use of broadcast and unicast
663 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
664 * messages, unless the client knows the address of a DHCP server.
665 * The client unicasts DHCPRELEASE messages to the server. Because
666 * the client is declining the use of the IP address supplied by the server,
667 * the client broadcasts DHCPDECLINE messages.
669 * When the DHCP client knows the address of a DHCP server, in either
670 * INIT or REBOOTING state, the client may use that address
671 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
672 * The client may also use unicast to send DHCPINFORM messages
673 * to a known DHCP server. If the client receives no response to DHCP
674 * messages sent to the IP address of a known DHCP server, the DHCP
675 * client reverts to using the IP broadcast address.
678 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet, uint32_t src_nip)
680 return udhcp_send_raw_packet(packet,
681 /*src*/ src_nip, CLIENT_PORT,
682 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
683 client_config.ifindex);
686 static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
689 return udhcp_send_kernel_packet(packet,
691 server, SERVER_PORT);
692 return raw_bcast_from_client_config_ifindex(packet, ciaddr);
695 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
696 /* NOINLINE: limit stack usage in caller */
697 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
699 struct dhcp_packet packet;
701 /* Fill in: op, htype, hlen, cookie, chaddr fields,
702 * random xid field (we override it below),
703 * client-id option (unless -C), message type option:
705 init_packet(&packet, DHCPDISCOVER);
709 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
711 /* Add options: maxsize,
712 * optionally: hostname, fqdn, vendorclass,
713 * "param req" option according to -O, options specified with -x
715 add_client_options(&packet);
717 bb_error_msg("sending %s", "discover");
718 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
721 /* Broadcast a DHCP request message */
722 /* RFC 2131 3.1 paragraph 3:
723 * "The client _broadcasts_ a DHCPREQUEST message..."
725 /* NOINLINE: limit stack usage in caller */
726 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
728 struct dhcp_packet packet;
732 * RFC 2131 4.3.2 DHCPREQUEST message
734 * If the DHCPREQUEST message contains a 'server identifier'
735 * option, the message is in response to a DHCPOFFER message.
736 * Otherwise, the message is a request to verify or extend an
737 * existing lease. If the client uses a 'client identifier'
738 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
739 * in all subsequent messages. If the client included a list
740 * of requested parameters in a DHCPDISCOVER message, it MUST
741 * include that list in all subsequent messages.
743 /* Fill in: op, htype, hlen, cookie, chaddr fields,
744 * random xid field (we override it below),
745 * client-id option (unless -C), message type option:
747 init_packet(&packet, DHCPREQUEST);
750 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
752 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
754 /* Add options: maxsize,
755 * optionally: hostname, fqdn, vendorclass,
756 * "param req" option according to -O, and options specified with -x
758 add_client_options(&packet);
760 addr.s_addr = requested;
761 bb_error_msg("sending select for %s", inet_ntoa(addr));
762 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
765 /* Unicast or broadcast a DHCP renew message */
766 /* NOINLINE: limit stack usage in caller */
767 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
769 struct dhcp_packet packet;
772 * RFC 2131 4.3.2 DHCPREQUEST message
774 * DHCPREQUEST generated during RENEWING state:
776 * 'server identifier' MUST NOT be filled in, 'requested IP address'
777 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
778 * client's IP address. In this situation, the client is completely
779 * configured, and is trying to extend its lease. This message will
780 * be unicast, so no relay agents will be involved in its
781 * transmission. Because 'giaddr' is therefore not filled in, the
782 * DHCP server will trust the value in 'ciaddr', and use it when
783 * replying to the client.
785 /* Fill in: op, htype, hlen, cookie, chaddr fields,
786 * random xid field (we override it below),
787 * client-id option (unless -C), message type option:
789 init_packet(&packet, DHCPREQUEST);
792 packet.ciaddr = ciaddr;
794 /* Add options: maxsize,
795 * optionally: hostname, fqdn, vendorclass,
796 * "param req" option according to -O, and options specified with -x
798 add_client_options(&packet);
800 bb_error_msg("sending %s", "renew");
801 return bcast_or_ucast(&packet, ciaddr, server);
804 #if ENABLE_FEATURE_UDHCPC_ARPING
805 /* Broadcast a DHCP decline message */
806 /* NOINLINE: limit stack usage in caller */
807 static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
809 struct dhcp_packet packet;
811 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
812 * client-id option (unless -C), message type option:
814 init_packet(&packet, DHCPDECLINE);
817 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
818 * but in case the server is buggy and wants DHCPDECLINE's xid
819 * to match the xid which started entire handshake,
820 * we use the same xid we used in initial DHCPDISCOVER:
824 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
825 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
827 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
829 bb_error_msg("sending %s", "decline");
830 return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
834 /* Unicast a DHCP release message */
835 static int send_release(uint32_t server, uint32_t ciaddr)
837 struct dhcp_packet packet;
839 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
840 * client-id option (unless -C), message type option:
842 init_packet(&packet, DHCPRELEASE);
844 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
845 packet.ciaddr = ciaddr;
847 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
849 bb_error_msg("sending %s", "release");
850 /* Note: normally we unicast here since "server" is not zero.
851 * However, there _are_ people who run "address-less" DHCP servers,
852 * and reportedly ISC dhcp client and Windows allow that.
854 return bcast_or_ucast(&packet, ciaddr, server);
857 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
858 /* NOINLINE: limit stack usage in caller */
859 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
862 struct ip_udp_dhcp_packet packet;
864 unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
867 struct cmsghdr *cmsg;
869 /* used to use just safe_read(fd, &packet, sizeof(packet))
870 * but we need to check for TP_STATUS_CSUMNOTREADY :(
872 iov.iov_base = &packet;
873 iov.iov_len = sizeof(packet);
874 memset(&msg, 0, sizeof(msg));
877 msg.msg_control = cmsgbuf;
878 msg.msg_controllen = sizeof(cmsgbuf);
880 bytes = recvmsg(fd, &msg, 0);
884 log1("packet read error, ignoring");
885 /* NB: possible down interface, etc. Caller should pause. */
886 return bytes; /* returns -1 */
891 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
892 log1("packet is too short, ignoring");
896 if (bytes < ntohs(packet.ip.tot_len)) {
897 /* packet is bigger than sizeof(packet), we did partial read */
898 log1("oversized packet, ignoring");
902 /* ignore any extra garbage bytes */
903 bytes = ntohs(packet.ip.tot_len);
905 /* make sure its the right packet for us, and that it passes sanity checks */
906 if (packet.ip.protocol != IPPROTO_UDP
907 || packet.ip.version != IPVERSION
908 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
909 || packet.udp.dest != htons(CLIENT_PORT)
910 /* || bytes > (int) sizeof(packet) - can't happen */
911 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
913 log1("unrelated/bogus packet, ignoring");
917 /* verify IP checksum */
918 check = packet.ip.check;
920 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
921 log1("bad IP header checksum, ignoring");
925 for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
926 if (cmsg->cmsg_level == SOL_PACKET
927 && cmsg->cmsg_type == PACKET_AUXDATA
929 /* some VMs don't checksum UDP and TCP data
930 * they send to the same physical machine,
931 * here we detect this case:
933 struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
934 if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
935 goto skip_udp_sum_check;
939 /* verify UDP checksum. IP header has to be modified for this */
940 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
941 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
942 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
943 check = packet.udp.check;
944 packet.udp.check = 0;
945 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
946 log1("packet with bad UDP checksum received, ignoring");
951 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
952 bb_error_msg("packet with bad magic, ignoring");
956 log1("received %s", "a packet");
957 udhcp_dump_packet(&packet.data);
959 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
960 memcpy(dhcp_pkt, &packet.data, bytes);
967 static int sockfd = -1;
969 #define LISTEN_NONE 0
970 #define LISTEN_KERNEL 1
972 static smallint listen_mode;
974 /* initial state: (re)start DHCP negotiation */
975 #define INIT_SELECTING 0
976 /* discover was sent, DHCPOFFER reply received */
978 /* select/renew was sent, DHCPACK reply received */
980 /* half of lease passed, want to renew it by sending unicast renew requests */
982 /* renew requests were not answered, lease is almost over, send broadcast renew */
984 /* manually requested renew (SIGUSR1) */
985 #define RENEW_REQUESTED 5
986 /* release, possibly manually requested (SIGUSR2) */
988 static smallint state;
990 static int udhcp_raw_socket(int ifindex)
993 struct sockaddr_ll sock;
995 log1("opening raw socket on ifindex %d", ifindex); //log2?
997 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
999 * SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
1000 * ETH_P_IP: want to receive only packets with IPv4 eth type
1002 log1("got raw socket fd"); //log2?
1004 sock.sll_family = AF_PACKET;
1005 sock.sll_protocol = htons(ETH_P_IP);
1006 sock.sll_ifindex = ifindex;
1007 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
1009 #if 0 /* Several users reported breakage when BPF filter is used */
1010 if (CLIENT_PORT == 68) {
1011 /* Use only if standard port is in use */
1013 * I've selected not to see LL header, so BPF doesn't see it, too.
1014 * The filter may also pass non-IP and non-ARP packets, but we do
1015 * a more complete check when receiving the message in userspace.
1017 * and filter shamelessly stolen from:
1019 * http://www.flamewarmaster.de/software/dhcpclient/
1021 * There are a few other interesting ideas on that page (look under
1022 * "Motivation"). Use of netlink events is most interesting. Think
1023 * of various network servers listening for events and reconfiguring.
1024 * That would obsolete sending HUP signals and/or make use of restarts.
1026 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1029 static const struct sock_filter filter_instr[] = {
1030 /* load 9th byte (protocol) */
1031 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1032 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
1033 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1034 /* L1: load halfword from offset 6 (flags and frag offset) */
1035 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1036 /* jump to L4 if any bits in frag offset field are set, else to L2 */
1037 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1038 /* L2: skip IP header (load index reg with header len) */
1039 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1040 /* load udp destination port from halfword[header_len + 2] */
1041 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1042 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1043 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1044 /* L3: accept packet ("accept 0x7fffffff bytes") */
1045 /* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1046 BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1047 /* L4: discard packet ("accept zero bytes") */
1048 BPF_STMT(BPF_RET|BPF_K, 0),
1050 static const struct sock_fprog filter_prog = {
1051 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1052 /* casting const away: */
1053 .filter = (struct sock_filter *) filter_instr,
1055 /* Ignoring error (kernel may lack support for this) */
1056 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1057 sizeof(filter_prog)) >= 0)
1058 log1("attached filter to raw socket fd"); // log?
1062 if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1063 if (errno != ENOPROTOOPT)
1064 log1("can't set PACKET_AUXDATA on raw socket");
1067 log1("created raw socket");
1072 static void change_listen_mode(int new_mode)
1074 log1("entering listen mode: %s",
1075 new_mode != LISTEN_NONE
1076 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1080 listen_mode = new_mode;
1085 if (new_mode == LISTEN_KERNEL)
1086 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1087 else if (new_mode != LISTEN_NONE)
1088 sockfd = udhcp_raw_socket(client_config.ifindex);
1089 /* else LISTEN_NONE: sockfd stays closed */
1092 /* Called only on SIGUSR1 */
1093 static void perform_renew(void)
1095 bb_error_msg("performing DHCP renew");
1098 change_listen_mode(LISTEN_KERNEL);
1101 state = RENEW_REQUESTED;
1103 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1104 udhcp_run_script(NULL, "deconfig");
1107 change_listen_mode(LISTEN_RAW);
1108 state = INIT_SELECTING;
1110 case INIT_SELECTING:
1115 static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1117 char buffer[sizeof("255.255.255.255")];
1118 struct in_addr temp_addr;
1120 /* send release packet */
1122 || state == RENEWING
1123 || state == REBINDING
1124 || state == RENEW_REQUESTED
1126 temp_addr.s_addr = server_addr;
1127 strcpy(buffer, inet_ntoa(temp_addr));
1128 temp_addr.s_addr = requested_ip;
1129 bb_error_msg("unicasting a release of %s to %s",
1130 inet_ntoa(temp_addr), buffer);
1131 send_release(server_addr, requested_ip); /* unicast */
1133 bb_error_msg("entering released state");
1135 * We can be here on: SIGUSR2,
1136 * or on exit (SIGTERM) and -R "release on quit" is specified.
1137 * Users requested to be notified in all cases, even if not in one
1138 * of the states above.
1140 udhcp_run_script(NULL, "deconfig");
1142 change_listen_mode(LISTEN_NONE);
1146 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1149 int len = strnlen(str, 255);
1150 storage = xzalloc(len + extra + OPT_DATA);
1151 storage[OPT_CODE] = code;
1152 storage[OPT_LEN] = len + extra;
1153 memcpy(storage + extra + OPT_DATA, str, len);
1158 static void client_background(void)
1161 logmode &= ~LOGMODE_STDIO;
1162 /* rewrite pidfile, as our pid is different now */
1163 write_pidfile(client_config.pidfile);
1167 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1168 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1170 //usage:# define IF_UDHCP_VERBOSE(...)
1172 //usage:#define udhcpc_trivial_usage
1173 //usage: "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1174 //usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1175 //usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1176 //usage:#define udhcpc_full_usage "\n"
1177 //usage: IF_LONG_OPTS(
1178 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1179 //usage: IF_FEATURE_UDHCP_PORT(
1180 //usage: "\n -P,--client-port PORT Use PORT (default 68)"
1182 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1183 //usage: "\n -p,--pidfile FILE Create pidfile"
1184 //usage: "\n -B,--broadcast Request broadcast replies"
1185 //usage: "\n -t,--retries N Send up to N discover packets (default 3)"
1186 //usage: "\n -T,--timeout SEC Pause between packets (default 3)"
1187 //usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
1188 //usage: "\n -n,--now Exit if lease is not obtained"
1189 //usage: "\n -q,--quit Exit after obtaining lease"
1190 //usage: "\n -R,--release Release IP on exit"
1191 //usage: "\n -f,--foreground Run in foreground"
1192 //usage: USE_FOR_MMU(
1193 //usage: "\n -b,--background Background if lease is not obtained"
1195 //usage: "\n -S,--syslog Log to syslog too"
1196 //usage: IF_FEATURE_UDHCPC_ARPING(
1197 //usage: "\n -a[MSEC],--arping[=MSEC] Validate offered address with ARP ping"
1199 //usage: "\n -r,--request IP Request this IP address"
1200 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1201 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1202 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1203 //usage: "\n Examples of string, numeric, and hex byte opts:"
1204 //usage: "\n -x hostname:bbox - option 12"
1205 //usage: "\n -x lease:3600 - option 51 (lease time)"
1206 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1207 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1208 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1209 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1210 //usage: IF_UDHCP_VERBOSE(
1211 //usage: "\n -v Verbose"
1214 //usage: IF_NOT_LONG_OPTS(
1215 //usage: "\n -i IFACE Interface to use (default eth0)"
1216 //usage: IF_FEATURE_UDHCP_PORT(
1217 //usage: "\n -P PORT Use PORT (default 68)"
1219 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1220 //usage: "\n -p FILE Create pidfile"
1221 //usage: "\n -B Request broadcast replies"
1222 //usage: "\n -t N Send up to N discover packets (default 3)"
1223 //usage: "\n -T SEC Pause between packets (default 3)"
1224 //usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1225 //usage: "\n -n Exit if lease is not obtained"
1226 //usage: "\n -q Exit after obtaining lease"
1227 //usage: "\n -R Release IP on exit"
1228 //usage: "\n -f Run in foreground"
1229 //usage: USE_FOR_MMU(
1230 //usage: "\n -b Background if lease is not obtained"
1232 //usage: "\n -S Log to syslog too"
1233 //usage: IF_FEATURE_UDHCPC_ARPING(
1234 //usage: "\n -a[MSEC] Validate offered address with ARP ping"
1236 //usage: "\n -r IP Request this IP address"
1237 //usage: "\n -o Don't request any options (unless -O is given)"
1238 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1239 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1240 //usage: "\n Examples of string, numeric, and hex byte opts:"
1241 //usage: "\n -x hostname:bbox - option 12"
1242 //usage: "\n -x lease:3600 - option 51 (lease time)"
1243 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1244 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1245 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1246 //usage: "\n -C Don't send MAC as client identifier"
1247 //usage: IF_UDHCP_VERBOSE(
1248 //usage: "\n -v Verbose"
1251 //usage: "\nSignals:"
1252 //usage: "\n USR1 Renew lease"
1253 //usage: "\n USR2 Release lease"
1256 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1257 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1260 const char *str_V, *str_h, *str_F, *str_r;
1261 IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1262 IF_FEATURE_UDHCP_PORT(char *str_P;)
1263 void *clientid_mac_ptr;
1264 llist_t *list_O = NULL;
1265 llist_t *list_x = NULL;
1266 int tryagain_timeout = 20;
1267 int discover_timeout = 3;
1268 int discover_retries = 3;
1269 uint32_t server_addr = server_addr; /* for compiler */
1270 uint32_t requested_ip = 0;
1271 uint32_t xid = xid; /* for compiler */
1273 int timeout; /* must be signed */
1274 unsigned already_waited_sec;
1276 IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1281 setup_common_bufsiz();
1283 /* Default options */
1284 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1285 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1286 client_config.interface = "eth0";
1287 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1288 str_V = "udhcp "BB_VER;
1290 /* Parse command line */
1291 /* O,x: list; -T,-t,-A take numeric param */
1292 IF_UDHCP_VERBOSE(opt_complementary = "vv";)
1293 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1294 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:+t:+SA:+O:*ox:*fB"
1296 IF_FEATURE_UDHCPC_ARPING("a::")
1297 IF_FEATURE_UDHCP_PORT("P:")
1299 , &str_V, &str_h, &str_h, &str_F
1300 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1301 , &client_config.script /* s */
1302 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1305 IF_FEATURE_UDHCPC_ARPING(, &str_a)
1306 IF_FEATURE_UDHCP_PORT(, &str_P)
1307 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1309 if (opt & (OPT_h|OPT_H)) {
1311 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1312 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1315 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1316 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1317 /* Flag bits: 0000NEOS
1318 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1319 * O: 1 = Server indicates to client that DNS has been updated regardless
1320 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1321 * not "host.domain.com". Format 0 is obsolete.
1322 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1323 * Two [0] bytes which follow are deprecated and must be 0.
1325 client_config.fqdn[OPT_DATA + 0] = 0x1;
1326 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1327 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1330 requested_ip = inet_addr(str_r);
1331 #if ENABLE_FEATURE_UDHCP_PORT
1333 CLIENT_PORT = xatou16(str_P);
1334 SERVER_PORT = CLIENT_PORT - 1;
1337 IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1339 char *optstr = llist_pop(&list_O);
1340 unsigned n = bb_strtou(optstr, NULL, 0);
1341 if (errno || n > 254) {
1342 n = udhcp_option_idx(optstr);
1343 n = dhcp_optflags[n].code;
1345 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1347 if (!(opt & OPT_o)) {
1349 for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1350 if (dhcp_optflags[i].flags & OPTION_REQ) {
1351 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1356 char *optstr = llist_pop(&list_x);
1357 char *colon = strchr(optstr, ':');
1360 /* now it looks similar to udhcpd's config file line:
1361 * "optname optval", using the common routine: */
1362 udhcp_str2optset(optstr, &client_config.options);
1365 if (udhcp_read_interface(client_config.interface,
1366 &client_config.ifindex,
1368 client_config.client_mac)
1373 clientid_mac_ptr = NULL;
1374 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1375 /* not suppressed and not set, set the default client ID */
1376 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1377 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1378 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1379 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1381 if (str_V[0] != '\0') {
1382 // can drop -V, str_V, client_config.vendorclass,
1383 // but need to add "vendor" to the list of recognized
1384 // string opts for this to work;
1385 // and need to tweak add_client_options() too...
1386 // ...so the question is, should we?
1387 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1388 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1392 /* on NOMMU reexec (i.e., background) early */
1393 if (!(opt & OPT_f)) {
1394 bb_daemonize_or_rexec(0 /* flags */, argv);
1395 logmode = LOGMODE_NONE;
1399 openlog(applet_name, LOG_PID, LOG_DAEMON);
1400 logmode |= LOGMODE_SYSLOG;
1403 /* Make sure fd 0,1,2 are open */
1404 bb_sanitize_stdio();
1405 /* Equivalent of doing a fflush after every \n */
1407 /* Create pidfile */
1408 write_pidfile(client_config.pidfile);
1409 /* Goes to stdout (unless NOMMU) and possibly syslog */
1410 bb_error_msg("started, v"BB_VER);
1411 /* Set up the signal pipe */
1413 /* We want random_xid to be random... */
1414 srand(monotonic_us());
1416 state = INIT_SELECTING;
1417 udhcp_run_script(NULL, "deconfig");
1418 change_listen_mode(LISTEN_RAW);
1421 already_waited_sec = 0;
1423 /* Main event loop. select() waits on signal pipe and possibly
1425 * "continue" statements in code below jump to the top of the loop.
1429 struct dhcp_packet packet;
1430 /* silence "uninitialized!" warning */
1431 unsigned timestamp_before_wait = timestamp_before_wait;
1433 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1435 /* Was opening raw or udp socket here
1436 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1437 * but on fast network renew responses return faster
1438 * than we open sockets. Thus this code is moved
1439 * to change_listen_mode(). Thus we open listen socket
1440 * BEFORE we send renew request (see "case BOUND:"). */
1442 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1444 tv.tv_sec = timeout - already_waited_sec;
1447 /* If we already timed out, fall through with retval = 0, else... */
1448 if ((int)tv.tv_sec > 0) {
1449 log1("waiting on select %u seconds", (int)tv.tv_sec);
1450 timestamp_before_wait = (unsigned)monotonic_sec();
1451 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1453 /* EINTR? A signal was caught, don't panic */
1454 if (errno == EINTR) {
1455 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1458 /* Else: an error occured, panic! */
1459 bb_perror_msg_and_die("select");
1463 /* If timeout dropped to zero, time to become active:
1464 * resend discover/renew/whatever
1467 /* When running on a bridge, the ifindex may have changed
1468 * (e.g. if member interfaces were added/removed
1469 * or if the status of the bridge changed).
1470 * Refresh ifindex and client_mac:
1472 if (udhcp_read_interface(client_config.interface,
1473 &client_config.ifindex,
1475 client_config.client_mac)
1477 goto ret0; /* iface is gone? */
1479 if (clientid_mac_ptr)
1480 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1482 /* We will restart the wait in any case */
1483 already_waited_sec = 0;
1486 case INIT_SELECTING:
1487 if (!discover_retries || packet_num < discover_retries) {
1488 if (packet_num == 0)
1491 send_discover(xid, requested_ip);
1492 timeout = discover_timeout;
1497 udhcp_run_script(NULL, "leasefail");
1498 #if BB_MMU /* -b is not supported on NOMMU */
1499 if (opt & OPT_b) { /* background if no lease */
1500 bb_error_msg("no lease, forking to background");
1501 client_background();
1502 /* do not background again! */
1503 opt = ((opt & ~OPT_b) | OPT_f);
1506 if (opt & OPT_n) { /* abort if no lease */
1507 bb_error_msg("no lease, failing");
1511 /* wait before trying again */
1512 timeout = tryagain_timeout;
1516 if (packet_num < 3) {
1517 /* send broadcast select packet */
1518 send_select(xid, server_addr, requested_ip);
1519 timeout = discover_timeout;
1523 /* Timed out, go back to init state.
1524 * "discover...select...discover..." loops
1525 * were seen in the wild. Treat them similarly
1526 * to "no response to discover" case */
1527 change_listen_mode(LISTEN_RAW);
1528 state = INIT_SELECTING;
1531 /* 1/2 lease passed, enter renewing state */
1533 client_config.first_secs = 0; /* make secs field count from 0 */
1534 change_listen_mode(LISTEN_KERNEL);
1535 log1("entering renew state");
1536 /* fall right through */
1537 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1538 case_RENEW_REQUESTED:
1541 /* send an unicast renew request */
1542 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1543 * a new UDP socket for sending inside send_renew.
1544 * I hazard to guess existing listening socket
1545 * is somehow conflicting with it, but why is it
1546 * not deterministic then?! Strange.
1547 * Anyway, it does recover by eventually failing through
1548 * into INIT_SELECTING state.
1550 send_renew(xid, server_addr, requested_ip);
1554 /* Timed out, enter rebinding state */
1555 log1("entering rebinding state");
1557 /* fall right through */
1559 /* Switch to bcast receive */
1560 change_listen_mode(LISTEN_RAW);
1561 /* Lease is *really* about to run out,
1562 * try to find DHCP server using broadcast */
1564 /* send a broadcast renew request */
1565 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1569 /* Timed out, enter init state */
1570 bb_error_msg("lease lost, entering init state");
1571 udhcp_run_script(NULL, "deconfig");
1572 state = INIT_SELECTING;
1573 client_config.first_secs = 0; /* make secs field count from 0 */
1574 /*timeout = 0; - already is */
1577 /* case RELEASED: */
1579 /* yah, I know, *you* say it would never happen */
1581 continue; /* back to main loop */
1582 } /* if select timed out */
1584 /* select() didn't timeout, something happened */
1586 /* Is it a signal? */
1587 /* note: udhcp_sp_read checks FD_ISSET before reading */
1588 switch (udhcp_sp_read(&rfds)) {
1590 client_config.first_secs = 0; /* make secs field count from 0 */
1591 already_waited_sec = 0;
1593 if (state == RENEW_REQUESTED) {
1594 /* We might be either on the same network
1595 * (in which case renew might work),
1596 * or we might be on a completely different one
1597 * (in which case renew won't ever succeed).
1598 * For the second case, must make sure timeout
1599 * is not too big, or else we can send
1600 * futile renew requests for hours.
1601 * (Ab)use -A TIMEOUT value (usually 20 sec)
1602 * as a cap on the timeout.
1604 if (timeout > tryagain_timeout)
1605 timeout = tryagain_timeout;
1606 goto case_RENEW_REQUESTED;
1608 /* Start things over */
1610 /* Kill any timeouts, user wants this to hurry along */
1614 perform_release(server_addr, requested_ip);
1618 bb_error_msg("received %s", "SIGTERM");
1622 /* Is it a packet? */
1623 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1629 /* A packet is ready, read it */
1630 if (listen_mode == LISTEN_KERNEL)
1631 len = udhcp_recv_kernel_packet(&packet, sockfd);
1633 len = udhcp_recv_raw_packet(&packet, sockfd);
1635 /* Error is severe, reopen socket */
1636 bb_error_msg("read error: %s, reopening socket", strerror(errno));
1637 sleep(discover_timeout); /* 3 seconds by default */
1638 change_listen_mode(listen_mode); /* just close and reopen */
1640 /* If this packet will turn out to be unrelated/bogus,
1641 * we will go back and wait for next one.
1642 * Be sure timeout is properly decreased. */
1643 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1648 if (packet.xid != xid) {
1649 log1("xid %x (our is %x), ignoring packet",
1650 (unsigned)packet.xid, (unsigned)xid);
1654 /* Ignore packets that aren't for us */
1655 if (packet.hlen != 6
1656 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1658 //FIXME: need to also check that last 10 bytes are zero
1659 log1("chaddr does not match, ignoring packet"); // log2?
1663 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1664 if (message == NULL) {
1665 bb_error_msg("no message type option, ignoring packet");
1670 case INIT_SELECTING:
1671 /* Must be a DHCPOFFER */
1672 if (*message == DHCPOFFER) {
1675 /* What exactly is server's IP? There are several values.
1676 * Example DHCP offer captured with tchdump:
1678 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1680 * Your-IP 10.34.25.202
1681 * Server-IP 10.34.32.125 // "next server" IP
1682 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1684 * DHCP-Message Option 53, length 1: Offer
1685 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1686 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1688 * We think that real server IP (one to use in renew/release)
1689 * is one in Server-ID option. But I am not 100% sure.
1690 * IP header's src and Gateway-IP (same in this example)
1692 * "Next server" and router are definitely wrong ones to use, though...
1694 /* We used to ignore pcakets without DHCP_SERVER_ID.
1695 * I've got user reports from people who run "address-less" servers.
1696 * They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1697 * They say ISC DHCP client supports this case.
1700 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1702 bb_error_msg("no server ID, using 0.0.0.0");
1704 /* it IS unaligned sometimes, don't "optimize" */
1705 move_from_unaligned32(server_addr, temp);
1707 /*xid = packet.xid; - already is */
1708 requested_ip = packet.yiaddr;
1710 /* enter requesting state */
1714 already_waited_sec = 0;
1719 case RENEW_REQUESTED:
1721 if (*message == DHCPACK) {
1723 uint32_t lease_seconds;
1724 struct in_addr temp_addr;
1727 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1729 bb_error_msg("no lease time with ACK, using 1 hour lease");
1730 lease_seconds = 60 * 60;
1732 /* it IS unaligned sometimes, don't "optimize" */
1733 move_from_unaligned32(lease_seconds, temp);
1734 lease_seconds = ntohl(lease_seconds);
1735 /* paranoia: must not be too small and not prone to overflows */
1736 if (lease_seconds < 0x10)
1737 lease_seconds = 0x10;
1738 if (lease_seconds >= 0x10000000)
1739 lease_seconds = 0x0fffffff;
1741 #if ENABLE_FEATURE_UDHCPC_ARPING
1743 /* RFC 2131 3.1 paragraph 5:
1744 * "The client receives the DHCPACK message with configuration
1745 * parameters. The client SHOULD perform a final check on the
1746 * parameters (e.g., ARP for allocated network address), and notes
1747 * the duration of the lease specified in the DHCPACK message. At this
1748 * point, the client is configured. If the client detects that the
1749 * address is already in use (e.g., through the use of ARP),
1750 * the client MUST send a DHCPDECLINE message to the server and restarts
1751 * the configuration process..." */
1752 if (!arpping(packet.yiaddr,
1755 client_config.client_mac,
1756 client_config.interface,
1759 bb_error_msg("offered address is in use "
1760 "(got ARP reply), declining");
1761 send_decline(/*xid,*/ server_addr, packet.yiaddr);
1763 if (state != REQUESTING)
1764 udhcp_run_script(NULL, "deconfig");
1765 change_listen_mode(LISTEN_RAW);
1766 state = INIT_SELECTING;
1767 client_config.first_secs = 0; /* make secs field count from 0 */
1769 timeout = tryagain_timeout;
1771 already_waited_sec = 0;
1772 continue; /* back to main loop */
1776 /* enter bound state */
1777 temp_addr.s_addr = packet.yiaddr;
1778 bb_error_msg("lease of %s obtained, lease time %u",
1779 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1780 requested_ip = packet.yiaddr;
1782 start = monotonic_sec();
1783 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1784 already_waited_sec = (unsigned)monotonic_sec() - start;
1785 timeout = lease_seconds / 2;
1786 if ((unsigned)timeout < already_waited_sec) {
1787 /* Something went wrong. Back to discover state */
1788 timeout = already_waited_sec = 0;
1792 change_listen_mode(LISTEN_NONE);
1793 if (opt & OPT_q) { /* quit after lease */
1796 /* future renew failures should not exit (JM) */
1798 #if BB_MMU /* NOMMU case backgrounded earlier */
1799 if (!(opt & OPT_f)) {
1800 client_background();
1801 /* do not background again! */
1802 opt = ((opt & ~OPT_b) | OPT_f);
1805 /* make future renew packets use different xid */
1806 /* xid = random_xid(); ...but why bother? */
1808 continue; /* back to main loop */
1810 if (*message == DHCPNAK) {
1811 /* If network has more than one DHCP server,
1812 * "wrong" server can reply first, with a NAK.
1813 * Do not interpret it as a NAK from "our" server.
1815 if (server_addr != 0) {
1819 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1822 log1("received DHCP NAK with wrong"
1823 " server ID, ignoring packet");
1826 move_from_unaligned32(svid, temp);
1827 if (svid != server_addr)
1828 goto non_matching_svid;
1830 /* return to init state */
1831 bb_error_msg("received %s", "DHCP NAK");
1832 udhcp_run_script(&packet, "nak");
1833 if (state != REQUESTING)
1834 udhcp_run_script(NULL, "deconfig");
1835 change_listen_mode(LISTEN_RAW);
1836 sleep(3); /* avoid excessive network traffic */
1837 state = INIT_SELECTING;
1838 client_config.first_secs = 0; /* make secs field count from 0 */
1842 already_waited_sec = 0;
1845 /* case BOUND: - ignore all packets */
1846 /* case RELEASED: - ignore all packets */
1848 /* back to main loop */
1849 } /* for (;;) - main loop ends */
1852 if (opt & OPT_R) /* release on quit */
1853 perform_release(server_addr, requested_ip);
1856 /*if (client_config.pidfile) - remove_pidfile has its own check */
1857 remove_pidfile(client_config.pidfile);