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 <netpacket/packet.h>
30 #include <linux/filter.h>
32 /* struct client_config_t client_config is in bb_common_bufsiz1 */
36 static const char udhcpc_longopts[] ALIGN1 =
37 "clientid-none\0" No_argument "C"
38 "vendorclass\0" Required_argument "V"
39 "hostname\0" Required_argument "H"
40 "fqdn\0" Required_argument "F"
41 "interface\0" Required_argument "i"
42 "now\0" No_argument "n"
43 "pidfile\0" Required_argument "p"
44 "quit\0" No_argument "q"
45 "release\0" No_argument "R"
46 "request\0" Required_argument "r"
47 "script\0" Required_argument "s"
48 "timeout\0" Required_argument "T"
49 "version\0" No_argument "v"
50 "retries\0" Required_argument "t"
51 "tryagain\0" Required_argument "A"
52 "syslog\0" No_argument "S"
53 "request-option\0" Required_argument "O"
54 "no-default-options\0" No_argument "o"
55 "foreground\0" No_argument "f"
56 "background\0" No_argument "b"
57 "broadcast\0" No_argument "B"
58 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
59 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
62 /* Must match getopt32 option string order */
85 /* The rest has variable bit positions, need to be clever */
87 USE_FOR_MMU( OPTBIT_b,)
88 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
89 IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
90 USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
91 IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
92 IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
96 /*** Script execution code ***/
98 /* get a rough idea of how long an option will be (rounding up...) */
99 static const uint8_t len_of_option_as_string[] = {
100 [OPTION_IP ] = sizeof("255.255.255.255 "),
101 [OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
102 [OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
103 [OPTION_6RD ] = sizeof("32 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
104 [OPTION_STRING ] = 1,
105 #if ENABLE_FEATURE_UDHCP_RFC3397
106 [OPTION_DNS_STRING ] = 1, /* unused */
107 /* Hmmm, this severely overestimates size if SIP_SERVERS option
108 * is in domain name form: N-byte option in binary form
109 * mallocs ~16*N bytes. But it is freed almost at once.
111 [OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
113 // [OPTION_BOOLEAN ] = sizeof("yes "),
114 [OPTION_U8 ] = sizeof("255 "),
115 [OPTION_U16 ] = sizeof("65535 "),
116 // [OPTION_S16 ] = sizeof("-32768 "),
117 [OPTION_U32 ] = sizeof("4294967295 "),
118 [OPTION_S32 ] = sizeof("-2147483684 "),
121 /* note: ip is a pointer to an IP in network order, possibly misaliged */
122 static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
124 return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
127 static int sprint_nip6(char *dest, const char *pre, const uint8_t *ip)
129 char hexstrbuf[16 * 2];
130 bin2hex(hexstrbuf, (void*)ip, 16);
131 return sprintf(dest, "%s"
132 "%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s:%.4s",
145 /* really simple implementation, just count the bits */
146 static int mton(uint32_t mask)
149 mask = ntohl(mask); /* 111110000-like bit pattern */
157 /* Create "opt_name=opt_value" string */
158 static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
160 unsigned upper_length;
161 int len, type, optlen;
164 /* option points to OPT_DATA, need to go back and get OPT_LEN */
165 len = option[OPT_LEN - OPT_DATA];
167 type = optflag->flags & OPTION_TYPE_MASK;
168 optlen = dhcp_option_lengths[type];
169 upper_length = len_of_option_as_string[type]
170 * ((unsigned)(len + optlen - 1) / (unsigned)optlen);
172 dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
173 dest += sprintf(ret, "%s=", opt_name);
175 while (len >= optlen) {
180 dest += sprint_nip(dest, "", option);
185 dest += sprint_nip(dest, "", option + ip_ofs);
187 // case OPTION_BOOLEAN:
188 // dest += sprintf(dest, *option ? "yes" : "no");
191 dest += sprintf(dest, "%u", *option);
196 move_from_unaligned16(val_u16, option);
197 dest += sprintf(dest, "%u", ntohs(val_u16));
203 move_from_unaligned32(val_u32, option);
204 dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
208 memcpy(dest, option, len);
210 return ret; /* Short circuit this case */
211 case OPTION_STATIC_ROUTES: {
212 /* Option binary format:
213 * mask [one byte, 0..32]
214 * ip [big endian, 0..4 bytes depending on mask]
215 * router [big endian, 4 bytes]
218 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
220 const char *pfx = "";
222 while (len >= 1 + 4) { /* mask + 0-byte ip + router */
235 bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
236 while (--bytes >= 0) {
244 dest += sprint_nip(dest, pfx, (void*) &nip);
246 dest += sprintf(dest, "/%u ", mask);
248 dest += sprint_nip(dest, "", option);
256 /* Option binary format (see RFC 5969):
258 * 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
259 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
260 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
261 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
268 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
269 * | 6rdBRIPv4Address(es) |
273 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
275 * We convert it to a string
276 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
279 /* Sanity check: ensure that our length is at least 22 bytes, that
281 * 6rdPrefixLen <= 128,
282 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
283 * (2nd condition need no check - it follows from 1st and 3rd).
284 * If any of these requirements is not fulfilled, return with empty
289 && (option[1] + 32 - option[0]) <= 128
292 dest += sprintf(dest, "%u ", *option++);
294 dest += sprintf(dest, "%u ", *option++);
296 dest += sprint_nip6(dest, "", option);
299 /* 6rdBRIPv4Address(es) */
301 dest += sprint_nip(dest, " ", option);
311 #if ENABLE_FEATURE_UDHCP_RFC3397
312 case OPTION_DNS_STRING:
313 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
314 dest = dname_dec(option, len, ret);
319 /* error. return "optname=" string */
321 case OPTION_SIP_SERVERS:
322 /* Option binary format:
324 * type=0: domain names, dns-compressed
329 if (option[-1] == 0) {
330 dest = dname_dec(option, len, ret);
336 if (option[-1] == 1) {
337 const char *pfx = "";
342 dest += sprint_nip(dest, pfx, option);
352 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
353 // Should we bail out/warn if we see multi-ip option which is
354 // not allowed to be such (for example, DHCP_BROADCAST)? -
355 if (len <= 0 /* || !(optflag->flags & OPTION_LIST) */)
363 /* put all the parameters into the environment */
364 static char **fill_envp(struct dhcp_packet *packet)
369 const char *opt_name;
371 uint8_t overload = 0;
373 #define BITMAP unsigned
374 #define BBITS (sizeof(BITMAP) * 8)
375 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
376 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
377 BITMAP found_opts[256 / BBITS];
379 memset(found_opts, 0, sizeof(found_opts));
381 /* We need 6 elements for:
383 * "ip=N.N.N.N" from packet->yiaddr
384 * "siaddr=IP" from packet->siaddr_nip (unless 0)
385 * "boot_file=FILE" from packet->file (unless overloaded)
386 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
390 /* +1 element for each option, +2 for subnet option: */
392 /* note: do not search for "pad" (0) and "end" (255) options */
393 for (i = 1; i < 255; i++) {
394 temp = udhcp_get_option(packet, i);
396 if (i == DHCP_OPTION_OVERLOAD)
398 else if (i == DHCP_SUBNET)
399 envc++; /* for mton */
401 /*if (i != DHCP_MESSAGE_TYPE)*/
402 FOUND_OPTS(i) |= BMASK(i);
406 curr = envp = xzalloc(sizeof(envp[0]) * envc);
408 *curr = xasprintf("interface=%s", client_config.interface);
414 *curr = xmalloc(sizeof("ip=255.255.255.255"));
415 sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
418 opt_name = dhcp_option_strings;
421 uint8_t code = dhcp_optflags[i].code;
422 BITMAP *found_ptr = &FOUND_OPTS(code);
423 BITMAP found_mask = BMASK(code);
424 if (!(*found_ptr & found_mask))
426 *found_ptr &= ~found_mask; /* leave only unknown options */
427 temp = udhcp_get_option(packet, code);
428 *curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
430 if (code == DHCP_SUBNET) {
431 /* Subnet option: make things like "$ip/$mask" possible */
433 move_from_unaligned32(subnet, temp);
434 *curr = xasprintf("mask=%d", mton(subnet));
438 opt_name += strlen(opt_name) + 1;
441 if (packet->siaddr_nip) {
442 *curr = xmalloc(sizeof("siaddr=255.255.255.255"));
443 sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
446 if (!(overload & FILE_FIELD) && packet->file[0]) {
447 /* watch out for invalid packets */
448 *curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
451 if (!(overload & SNAME_FIELD) && packet->sname[0]) {
452 /* watch out for invalid packets */
453 *curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
456 /* Handle unknown options */
457 for (i = 0; i < 256;) {
458 BITMAP bitmap = FOUND_OPTS(i);
463 if (bitmap & BMASK(i)) {
466 temp = udhcp_get_option(packet, i);
467 /* udhcp_get_option returns ptr to data portion,
468 * need to go back to get len
470 len = temp[-OPT_DATA + OPT_LEN];
471 *curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
472 ofs = sprintf(*curr, "opt%u=", i);
473 *bin2hex(*curr + ofs, (void*) temp, len) = '\0';
481 /* Call a script with a par file and env vars */
482 static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
487 if (client_config.script == NULL)
490 envp = fill_envp(packet);
493 log1("Executing %s %s", client_config.script, name);
494 argv[0] = (char*) client_config.script;
495 argv[1] = (char*) name;
497 spawn_and_wait(argv);
499 for (curr = envp; *curr; curr++) {
501 bb_unsetenv_and_free(*curr);
507 /*** Sending/receiving packets ***/
509 static ALWAYS_INLINE uint32_t random_xid(void)
514 /* Initialize the packet with the proper defaults */
515 static void init_packet(struct dhcp_packet *packet, char type)
519 /* Fill in: op, htype, hlen, cookie fields; message type option: */
520 udhcp_init_header(packet, type);
522 packet->xid = random_xid();
524 client_config.last_secs = monotonic_sec();
525 if (client_config.first_secs == 0)
526 client_config.first_secs = client_config.last_secs;
527 secs = client_config.last_secs - client_config.first_secs;
528 packet->secs = htons(secs);
530 memcpy(packet->chaddr, client_config.client_mac, 6);
531 if (client_config.clientid)
532 udhcp_add_binary_option(packet, client_config.clientid);
535 static void add_client_options(struct dhcp_packet *packet)
540 udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
542 /* Add a "param req" option with the list of options we'd like to have
543 * from stubborn DHCP servers. Pull the data from the struct in common.c.
544 * No bounds checking because it goes towards the head of the packet. */
545 end = udhcp_end_option(packet->options);
547 for (i = 0; (c = dhcp_optflags[i].code) != 0; i++) {
548 if (( (dhcp_optflags[i].flags & OPTION_REQ)
549 && !client_config.no_default_options
551 || (client_config.opt_mask[c >> 3] & (1 << (c & 7)))
553 packet->options[end + OPT_DATA + len] = c;
558 packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
559 packet->options[end + OPT_LEN] = len;
560 packet->options[end + OPT_DATA + len] = DHCP_END;
563 if (client_config.vendorclass)
564 udhcp_add_binary_option(packet, client_config.vendorclass);
565 if (client_config.hostname)
566 udhcp_add_binary_option(packet, client_config.hostname);
567 if (client_config.fqdn)
568 udhcp_add_binary_option(packet, client_config.fqdn);
570 /* Request broadcast replies if we have no IP addr */
571 if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
572 packet->flags |= htons(BROADCAST_FLAG);
574 /* Add -x options if any */
576 struct option_set *curr = client_config.options;
578 udhcp_add_binary_option(packet, curr->data);
581 // if (client_config.sname)
582 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
583 // if (client_config.boot_file)
584 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
589 * 4.4.4 Use of broadcast and unicast
591 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
592 * messages, unless the client knows the address of a DHCP server.
593 * The client unicasts DHCPRELEASE messages to the server. Because
594 * the client is declining the use of the IP address supplied by the server,
595 * the client broadcasts DHCPDECLINE messages.
597 * When the DHCP client knows the address of a DHCP server, in either
598 * INIT or REBOOTING state, the client may use that address
599 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
600 * The client may also use unicast to send DHCPINFORM messages
601 * to a known DHCP server. If the client receives no response to DHCP
602 * messages sent to the IP address of a known DHCP server, the DHCP
603 * client reverts to using the IP broadcast address.
606 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet)
608 return udhcp_send_raw_packet(packet,
609 /*src*/ INADDR_ANY, CLIENT_PORT,
610 /*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
611 client_config.ifindex);
614 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
615 /* NOINLINE: limit stack usage in caller */
616 static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
618 struct dhcp_packet packet;
620 /* Fill in: op, htype, hlen, cookie, chaddr fields,
621 * random xid field (we override it below),
622 * client-id option (unless -C), message type option:
624 init_packet(&packet, DHCPDISCOVER);
628 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
630 /* Add options: maxsize,
631 * optionally: hostname, fqdn, vendorclass,
632 * "param req" option according to -O, options specified with -x
634 add_client_options(&packet);
636 bb_info_msg("Sending discover...");
637 return raw_bcast_from_client_config_ifindex(&packet);
640 /* Broadcast a DHCP request message */
641 /* RFC 2131 3.1 paragraph 3:
642 * "The client _broadcasts_ a DHCPREQUEST message..."
644 /* NOINLINE: limit stack usage in caller */
645 static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
647 struct dhcp_packet packet;
651 * RFC 2131 4.3.2 DHCPREQUEST message
653 * If the DHCPREQUEST message contains a 'server identifier'
654 * option, the message is in response to a DHCPOFFER message.
655 * Otherwise, the message is a request to verify or extend an
656 * existing lease. If the client uses a 'client identifier'
657 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
658 * in all subsequent messages. If the client included a list
659 * of requested parameters in a DHCPDISCOVER message, it MUST
660 * include that list in all subsequent messages.
662 /* Fill in: op, htype, hlen, cookie, chaddr fields,
663 * random xid field (we override it below),
664 * client-id option (unless -C), message type option:
666 init_packet(&packet, DHCPREQUEST);
669 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
671 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
673 /* Add options: maxsize,
674 * optionally: hostname, fqdn, vendorclass,
675 * "param req" option according to -O, and options specified with -x
677 add_client_options(&packet);
679 addr.s_addr = requested;
680 bb_info_msg("Sending select for %s...", inet_ntoa(addr));
681 return raw_bcast_from_client_config_ifindex(&packet);
684 /* Unicast or broadcast a DHCP renew message */
685 /* NOINLINE: limit stack usage in caller */
686 static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
688 struct dhcp_packet packet;
691 * RFC 2131 4.3.2 DHCPREQUEST message
693 * DHCPREQUEST generated during RENEWING state:
695 * 'server identifier' MUST NOT be filled in, 'requested IP address'
696 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
697 * client's IP address. In this situation, the client is completely
698 * configured, and is trying to extend its lease. This message will
699 * be unicast, so no relay agents will be involved in its
700 * transmission. Because 'giaddr' is therefore not filled in, the
701 * DHCP server will trust the value in 'ciaddr', and use it when
702 * replying to the client.
704 /* Fill in: op, htype, hlen, cookie, chaddr fields,
705 * random xid field (we override it below),
706 * client-id option (unless -C), message type option:
708 init_packet(&packet, DHCPREQUEST);
711 packet.ciaddr = ciaddr;
713 /* Add options: maxsize,
714 * optionally: hostname, fqdn, vendorclass,
715 * "param req" option according to -O, and options specified with -x
717 add_client_options(&packet);
719 bb_info_msg("Sending renew...");
721 return udhcp_send_kernel_packet(&packet,
723 server, SERVER_PORT);
724 return raw_bcast_from_client_config_ifindex(&packet);
727 #if ENABLE_FEATURE_UDHCPC_ARPING
728 /* Broadcast a DHCP decline message */
729 /* NOINLINE: limit stack usage in caller */
730 static NOINLINE int send_decline(uint32_t xid, uint32_t server, uint32_t requested)
732 struct dhcp_packet packet;
734 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
735 * client-id option (unless -C), message type option:
737 init_packet(&packet, DHCPDECLINE);
739 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
740 * but in case the server is buggy and wants DHCPDECLINE's xid
741 * to match the xid which started entire handshake,
742 * we use the same xid we used in initial DHCPDISCOVER:
745 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
746 udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
748 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
750 bb_info_msg("Sending decline...");
751 return raw_bcast_from_client_config_ifindex(&packet);
755 /* Unicast a DHCP release message */
756 static int send_release(uint32_t server, uint32_t ciaddr)
758 struct dhcp_packet packet;
760 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
761 * client-id option (unless -C), message type option:
763 init_packet(&packet, DHCPRELEASE);
765 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
766 packet.ciaddr = ciaddr;
768 udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
770 bb_info_msg("Sending release...");
771 return udhcp_send_kernel_packet(&packet, ciaddr, CLIENT_PORT, server, SERVER_PORT);
774 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
775 /* NOINLINE: limit stack usage in caller */
776 static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
779 struct ip_udp_dhcp_packet packet;
782 memset(&packet, 0, sizeof(packet));
783 bytes = safe_read(fd, &packet, sizeof(packet));
785 log1("Packet read error, ignoring");
786 /* NB: possible down interface, etc. Caller should pause. */
787 return bytes; /* returns -1 */
790 if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
791 log1("Packet is too short, ignoring");
795 if (bytes < ntohs(packet.ip.tot_len)) {
796 /* packet is bigger than sizeof(packet), we did partial read */
797 log1("Oversized packet, ignoring");
801 /* ignore any extra garbage bytes */
802 bytes = ntohs(packet.ip.tot_len);
804 /* make sure its the right packet for us, and that it passes sanity checks */
805 if (packet.ip.protocol != IPPROTO_UDP
806 || packet.ip.version != IPVERSION
807 || packet.ip.ihl != (sizeof(packet.ip) >> 2)
808 || packet.udp.dest != htons(CLIENT_PORT)
809 /* || bytes > (int) sizeof(packet) - can't happen */
810 || ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
812 log1("Unrelated/bogus packet, ignoring");
816 /* verify IP checksum */
817 check = packet.ip.check;
819 if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
820 log1("Bad IP header checksum, ignoring");
824 /* verify UDP checksum. IP header has to be modified for this */
825 memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
826 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
827 packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
828 check = packet.udp.check;
829 packet.udp.check = 0;
830 if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
831 log1("Packet with bad UDP checksum received, ignoring");
835 if (packet.data.cookie != htonl(DHCP_MAGIC)) {
836 bb_info_msg("Packet with bad magic, ignoring");
840 log1("Got valid DHCP packet");
841 udhcp_dump_packet(&packet.data);
843 bytes -= sizeof(packet.ip) + sizeof(packet.udp);
844 memcpy(dhcp_pkt, &packet.data, bytes);
851 static int sockfd = -1;
853 #define LISTEN_NONE 0
854 #define LISTEN_KERNEL 1
856 static smallint listen_mode;
858 /* initial state: (re)start DHCP negotiation */
859 #define INIT_SELECTING 0
860 /* discover was sent, DHCPOFFER reply received */
862 /* select/renew was sent, DHCPACK reply received */
864 /* half of lease passed, want to renew it by sending unicast renew requests */
866 /* renew requests were not answered, lease is almost over, send broadcast renew */
868 /* manually requested renew (SIGUSR1) */
869 #define RENEW_REQUESTED 5
870 /* release, possibly manually requested (SIGUSR2) */
872 static smallint state;
874 static int udhcp_raw_socket(int ifindex)
877 struct sockaddr_ll sock;
882 * I've selected not to see LL header, so BPF doesn't see it, too.
883 * The filter may also pass non-IP and non-ARP packets, but we do
884 * a more complete check when receiving the message in userspace.
886 * and filter shamelessly stolen from:
888 * http://www.flamewarmaster.de/software/dhcpclient/
890 * There are a few other interesting ideas on that page (look under
891 * "Motivation"). Use of netlink events is most interesting. Think
892 * of various network servers listening for events and reconfiguring.
893 * That would obsolete sending HUP signals and/or make use of restarts.
895 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
898 * TODO: make conditional?
900 static const struct sock_filter filter_instr[] = {
901 /* load 9th byte (protocol) */
902 BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
903 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
904 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
905 /* L1: load halfword from offset 6 (flags and frag offset) */
906 BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
907 /* jump to L4 if any bits in frag offset field are set, else to L2 */
908 BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
909 /* L2: skip IP header (load index reg with header len) */
910 BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
911 /* load udp destination port from halfword[header_len + 2] */
912 BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
913 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
914 BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
915 /* L3: accept packet */
916 BPF_STMT(BPF_RET|BPF_K, 0xffffffff),
917 /* L4: discard packet */
918 BPF_STMT(BPF_RET|BPF_K, 0),
920 static const struct sock_fprog filter_prog = {
921 .len = sizeof(filter_instr) / sizeof(filter_instr[0]),
922 /* casting const away: */
923 .filter = (struct sock_filter *) filter_instr,
926 log1("Opening raw socket on ifindex %d", ifindex); //log2?
928 fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
929 log1("Got raw socket fd %d", fd); //log2?
931 sock.sll_family = AF_PACKET;
932 sock.sll_protocol = htons(ETH_P_IP);
933 sock.sll_ifindex = ifindex;
934 xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
936 if (CLIENT_PORT == 68) {
937 /* Use only if standard port is in use */
938 /* Ignoring error (kernel may lack support for this) */
939 if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
940 sizeof(filter_prog)) >= 0)
941 log1("Attached filter to raw socket fd %d", fd); // log?
944 log1("Created raw socket");
949 static void change_listen_mode(int new_mode)
951 log1("Entering listen mode: %s",
952 new_mode != LISTEN_NONE
953 ? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
957 listen_mode = new_mode;
962 if (new_mode == LISTEN_KERNEL)
963 sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
964 else if (new_mode != LISTEN_NONE)
965 sockfd = udhcp_raw_socket(client_config.ifindex);
966 /* else LISTEN_NONE: sockfd stays closed */
969 /* Called only on SIGUSR1 */
970 static void perform_renew(void)
972 bb_info_msg("Performing a DHCP renew");
975 change_listen_mode(LISTEN_KERNEL);
978 state = RENEW_REQUESTED;
980 case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
981 udhcp_run_script(NULL, "deconfig");
984 change_listen_mode(LISTEN_RAW);
985 state = INIT_SELECTING;
992 static void perform_release(uint32_t requested_ip, uint32_t server_addr)
994 char buffer[sizeof("255.255.255.255")];
995 struct in_addr temp_addr;
997 /* send release packet */
998 if (state == BOUND || state == RENEWING || state == REBINDING) {
999 temp_addr.s_addr = server_addr;
1000 strcpy(buffer, inet_ntoa(temp_addr));
1001 temp_addr.s_addr = requested_ip;
1002 bb_info_msg("Unicasting a release of %s to %s",
1003 inet_ntoa(temp_addr), buffer);
1004 send_release(server_addr, requested_ip); /* unicast */
1005 udhcp_run_script(NULL, "deconfig");
1007 bb_info_msg("Entering released state");
1009 change_listen_mode(LISTEN_NONE);
1013 static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1016 int len = strnlen(str, 255);
1017 storage = xzalloc(len + extra + OPT_DATA);
1018 storage[OPT_CODE] = code;
1019 storage[OPT_LEN] = len + extra;
1020 memcpy(storage + extra + OPT_DATA, str, len);
1025 static void client_background(void)
1028 logmode &= ~LOGMODE_STDIO;
1029 /* rewrite pidfile, as our pid is different now */
1030 write_pidfile(client_config.pidfile);
1034 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1035 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1037 //usage:# define IF_UDHCP_VERBOSE(...)
1039 //usage:#define udhcpc_trivial_usage
1040 //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
1041 //usage: " [-H HOSTNAME] [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
1042 //usage:#define udhcpc_full_usage "\n"
1043 //usage: IF_LONG_OPTS(
1044 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1045 //usage: "\n -p,--pidfile FILE Create pidfile"
1046 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1047 //usage: "\n -B,--broadcast Request broadcast replies"
1048 //usage: "\n -t,--retries N Send up to N discover packets"
1049 //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
1050 //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
1051 //usage: "\n -f,--foreground Run in foreground"
1052 //usage: USE_FOR_MMU(
1053 //usage: "\n -b,--background Background if lease is not obtained"
1055 //usage: "\n -n,--now Exit if lease is not obtained"
1056 //usage: "\n -q,--quit Exit after obtaining lease"
1057 //usage: "\n -R,--release Release IP on exit"
1058 //usage: "\n -S,--syslog Log to syslog too"
1059 //usage: IF_FEATURE_UDHCP_PORT(
1060 //usage: "\n -P,--client-port N Use port N (default 68)"
1062 //usage: IF_FEATURE_UDHCPC_ARPING(
1063 //usage: "\n -a,--arping Use arping to validate offered address"
1065 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1066 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1067 //usage: "\n -r,--request IP Request this IP address"
1068 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1069 //usage: "\n Examples of string, numeric, and hex byte opts:"
1070 //usage: "\n -x hostname:bbox - option 12"
1071 //usage: "\n -x lease:3600 - option 51 (lease time)"
1072 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1073 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1074 //usage: "\n -H,-h,--hostname NAME Send NAME as client hostname (default none)"
1075 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1076 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1077 //usage: IF_UDHCP_VERBOSE(
1078 //usage: "\n -v Verbose"
1081 //usage: IF_NOT_LONG_OPTS(
1082 //usage: "\n -i IFACE Interface to use (default eth0)"
1083 //usage: "\n -p FILE Create pidfile"
1084 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1085 //usage: "\n -B Request broadcast replies"
1086 //usage: "\n -t N Send up to N discover packets"
1087 //usage: "\n -T N Pause between packets (default 3 seconds)"
1088 //usage: "\n -A N Wait N seconds (default 20) after failure"
1089 //usage: "\n -f Run in foreground"
1090 //usage: USE_FOR_MMU(
1091 //usage: "\n -b Background if lease is not obtained"
1093 //usage: "\n -n Exit if lease is not obtained"
1094 //usage: "\n -q Exit after obtaining lease"
1095 //usage: "\n -R Release IP on exit"
1096 //usage: "\n -S Log to syslog too"
1097 //usage: IF_FEATURE_UDHCP_PORT(
1098 //usage: "\n -P N Use port N (default 68)"
1100 //usage: IF_FEATURE_UDHCPC_ARPING(
1101 //usage: "\n -a Use arping to validate offered address"
1103 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1104 //usage: "\n -o Don't request any options (unless -O is given)"
1105 //usage: "\n -r IP Request this IP address"
1106 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1107 //usage: "\n Examples of string, numeric, and hex byte opts:"
1108 //usage: "\n -x hostname:bbox - option 12"
1109 //usage: "\n -x lease:3600 - option 51 (lease time)"
1110 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1111 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1112 //usage: "\n -H,-h NAME Send NAME as client hostname (default none)"
1113 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1114 //usage: "\n -C Don't send MAC as client identifier"
1115 //usage: IF_UDHCP_VERBOSE(
1116 //usage: "\n -v Verbose"
1119 //usage: "\nSignals:"
1120 //usage: "\n USR1 Renew current lease"
1121 //usage: "\n USR2 Release current lease"
1124 int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1125 int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1127 uint8_t *temp, *message;
1128 const char *str_V, *str_h, *str_F, *str_r;
1129 IF_FEATURE_UDHCP_PORT(char *str_P;)
1130 void *clientid_mac_ptr;
1131 llist_t *list_O = NULL;
1132 llist_t *list_x = NULL;
1133 int tryagain_timeout = 20;
1134 int discover_timeout = 3;
1135 int discover_retries = 3;
1136 uint32_t server_addr = server_addr; /* for compiler */
1137 uint32_t requested_ip = 0;
1139 uint32_t lease_seconds = 0; /* can be given as 32-bit quantity */
1141 int timeout; /* must be signed */
1142 unsigned already_waited_sec;
1147 struct dhcp_packet packet;
1150 /* Default options */
1151 IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1152 IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1153 client_config.interface = "eth0";
1154 client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1155 str_V = "udhcp "BB_VER;
1157 /* Parse command line */
1158 /* O,x: list; -T,-t,-A take numeric param */
1159 opt_complementary = "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1160 IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1161 opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1163 IF_FEATURE_UDHCPC_ARPING("a")
1164 IF_FEATURE_UDHCP_PORT("P:")
1166 , &str_V, &str_h, &str_h, &str_F
1167 , &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1168 , &client_config.script /* s */
1169 , &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1172 IF_FEATURE_UDHCP_PORT(, &str_P)
1173 IF_UDHCP_VERBOSE(, &dhcp_verbose)
1175 if (opt & (OPT_h|OPT_H))
1176 client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1178 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1179 client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1180 /* Flag bits: 0000NEOS
1181 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1182 * O: 1 = Server indicates to client that DNS has been updated regardless
1183 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1184 * not "host.domain.com". Format 0 is obsolete.
1185 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1186 * Two [0] bytes which follow are deprecated and must be 0.
1188 client_config.fqdn[OPT_DATA + 0] = 0x1;
1189 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1190 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1193 requested_ip = inet_addr(str_r);
1194 #if ENABLE_FEATURE_UDHCP_PORT
1196 CLIENT_PORT = xatou16(str_P);
1197 SERVER_PORT = CLIENT_PORT - 1;
1201 client_config.no_default_options = 1;
1203 char *optstr = llist_pop(&list_O);
1204 unsigned n = bb_strtou(optstr, NULL, 0);
1205 if (errno || n > 254) {
1206 n = udhcp_option_idx(optstr);
1207 n = dhcp_optflags[n].code;
1209 client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1212 char *optstr = llist_pop(&list_x);
1213 char *colon = strchr(optstr, ':');
1216 /* now it looks similar to udhcpd's config file line:
1217 * "optname optval", using the common routine: */
1218 udhcp_str2optset(optstr, &client_config.options);
1221 if (udhcp_read_interface(client_config.interface,
1222 &client_config.ifindex,
1224 client_config.client_mac)
1229 clientid_mac_ptr = NULL;
1230 if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1231 /* not suppressed and not set, set the default client ID */
1232 client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1233 client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1234 clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1235 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1237 if (str_V[0] != '\0')
1238 client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1240 /* on NOMMU reexec (i.e., background) early */
1241 if (!(opt & OPT_f)) {
1242 bb_daemonize_or_rexec(0 /* flags */, argv);
1243 logmode = LOGMODE_NONE;
1247 openlog(applet_name, LOG_PID, LOG_DAEMON);
1248 logmode |= LOGMODE_SYSLOG;
1251 /* Make sure fd 0,1,2 are open */
1252 bb_sanitize_stdio();
1253 /* Equivalent of doing a fflush after every \n */
1255 /* Create pidfile */
1256 write_pidfile(client_config.pidfile);
1257 /* Goes to stdout (unless NOMMU) and possibly syslog */
1258 bb_info_msg("%s (v"BB_VER") started", applet_name);
1259 /* Set up the signal pipe */
1261 /* We want random_xid to be random... */
1262 srand(monotonic_us());
1264 state = INIT_SELECTING;
1265 udhcp_run_script(NULL, "deconfig");
1266 change_listen_mode(LISTEN_RAW);
1269 already_waited_sec = 0;
1271 /* Main event loop. select() waits on signal pipe and possibly
1273 * "continue" statements in code below jump to the top of the loop.
1276 /* silence "uninitialized!" warning */
1277 unsigned timestamp_before_wait = timestamp_before_wait;
1279 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1281 /* Was opening raw or udp socket here
1282 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1283 * but on fast network renew responses return faster
1284 * than we open sockets. Thus this code is moved
1285 * to change_listen_mode(). Thus we open listen socket
1286 * BEFORE we send renew request (see "case BOUND:"). */
1288 max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1290 tv.tv_sec = timeout - already_waited_sec;
1293 /* If we already timed out, fall through with retval = 0, else... */
1294 if ((int)tv.tv_sec > 0) {
1295 timestamp_before_wait = (unsigned)monotonic_sec();
1296 log1("Waiting on select...");
1297 retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1299 /* EINTR? A signal was caught, don't panic */
1300 if (errno == EINTR) {
1301 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1304 /* Else: an error occured, panic! */
1305 bb_perror_msg_and_die("select");
1309 /* If timeout dropped to zero, time to become active:
1310 * resend discover/renew/whatever
1313 /* When running on a bridge, the ifindex may have changed
1314 * (e.g. if member interfaces were added/removed
1315 * or if the status of the bridge changed).
1316 * Refresh ifindex and client_mac:
1318 if (udhcp_read_interface(client_config.interface,
1319 &client_config.ifindex,
1321 client_config.client_mac)
1323 return 1; /* iface is gone? */
1325 if (clientid_mac_ptr)
1326 memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1328 /* We will restart the wait in any case */
1329 already_waited_sec = 0;
1332 case INIT_SELECTING:
1333 if (packet_num < discover_retries) {
1334 if (packet_num == 0)
1337 send_discover(xid, requested_ip);
1338 timeout = discover_timeout;
1343 udhcp_run_script(NULL, "leasefail");
1344 #if BB_MMU /* -b is not supported on NOMMU */
1345 if (opt & OPT_b) { /* background if no lease */
1346 bb_info_msg("No lease, forking to background");
1347 client_background();
1348 /* do not background again! */
1349 opt = ((opt & ~OPT_b) | OPT_f);
1352 if (opt & OPT_n) { /* abort if no lease */
1353 bb_info_msg("No lease, failing");
1357 /* wait before trying again */
1358 timeout = tryagain_timeout;
1362 if (packet_num < discover_retries) {
1363 /* send broadcast select packet */
1364 send_select(xid, server_addr, requested_ip);
1365 timeout = discover_timeout;
1369 /* Timed out, go back to init state.
1370 * "discover...select...discover..." loops
1371 * were seen in the wild. Treat them similarly
1372 * to "no response to discover" case */
1373 change_listen_mode(LISTEN_RAW);
1374 state = INIT_SELECTING;
1377 /* 1/2 lease passed, enter renewing state */
1379 client_config.first_secs = 0; /* make secs field count from 0 */
1380 change_listen_mode(LISTEN_KERNEL);
1381 log1("Entering renew state");
1382 /* fall right through */
1383 case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1384 case_RENEW_REQUESTED:
1387 /* send an unicast renew request */
1388 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1389 * a new UDP socket for sending inside send_renew.
1390 * I hazard to guess existing listening socket
1391 * is somehow conflicting with it, but why is it
1392 * not deterministic then?! Strange.
1393 * Anyway, it does recover by eventually failing through
1394 * into INIT_SELECTING state.
1396 send_renew(xid, server_addr, requested_ip);
1400 /* Timed out, enter rebinding state */
1401 log1("Entering rebinding state");
1403 /* fall right through */
1405 /* Switch to bcast receive */
1406 change_listen_mode(LISTEN_RAW);
1407 /* Lease is *really* about to run out,
1408 * try to find DHCP server using broadcast */
1410 /* send a broadcast renew request */
1411 send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1415 /* Timed out, enter init state */
1416 bb_info_msg("Lease lost, entering init state");
1417 udhcp_run_script(NULL, "deconfig");
1418 state = INIT_SELECTING;
1419 client_config.first_secs = 0; /* make secs field count from 0 */
1420 /*timeout = 0; - already is */
1423 /* case RELEASED: */
1425 /* yah, I know, *you* say it would never happen */
1427 continue; /* back to main loop */
1428 } /* if select timed out */
1430 /* select() didn't timeout, something happened */
1432 /* Is it a signal? */
1433 /* note: udhcp_sp_read checks FD_ISSET before reading */
1434 switch (udhcp_sp_read(&rfds)) {
1436 client_config.first_secs = 0; /* make secs field count from 0 */
1437 already_waited_sec = 0;
1439 if (state == RENEW_REQUESTED) {
1440 /* We might be either on the same network
1441 * (in which case renew might work),
1442 * or we might be on a completely different one
1443 * (in which case renew won't ever succeed).
1444 * For the second case, must make sure timeout
1445 * is not too big, or else we can send
1446 * futile renew requests for hours.
1447 * (Ab)use -A TIMEOUT value (usually 20 sec)
1448 * as a cap on the timeout.
1450 if (timeout > tryagain_timeout)
1451 timeout = tryagain_timeout;
1452 goto case_RENEW_REQUESTED;
1454 /* Start things over */
1456 /* Kill any timeouts, user wants this to hurry along */
1460 perform_release(requested_ip, server_addr);
1464 bb_info_msg("Received SIGTERM");
1465 if (opt & OPT_R) /* release on quit */
1466 perform_release(requested_ip, server_addr);
1470 /* Is it a packet? */
1471 if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1477 /* A packet is ready, read it */
1478 if (listen_mode == LISTEN_KERNEL)
1479 len = udhcp_recv_kernel_packet(&packet, sockfd);
1481 len = udhcp_recv_raw_packet(&packet, sockfd);
1483 /* Error is severe, reopen socket */
1484 bb_info_msg("Read error: %s, reopening socket", strerror(errno));
1485 sleep(discover_timeout); /* 3 seconds by default */
1486 change_listen_mode(listen_mode); /* just close and reopen */
1488 /* If this packet will turn out to be unrelated/bogus,
1489 * we will go back and wait for next one.
1490 * Be sure timeout is properly decreased. */
1491 already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1496 if (packet.xid != xid) {
1497 log1("xid %x (our is %x), ignoring packet",
1498 (unsigned)packet.xid, (unsigned)xid);
1502 /* Ignore packets that aren't for us */
1503 if (packet.hlen != 6
1504 || memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1506 //FIXME: need to also check that last 10 bytes are zero
1507 log1("chaddr does not match, ignoring packet"); // log2?
1511 message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1512 if (message == NULL) {
1513 bb_error_msg("no message type option, ignoring packet");
1518 case INIT_SELECTING:
1519 /* Must be a DHCPOFFER to one of our xid's */
1520 if (*message == DHCPOFFER) {
1521 /* TODO: why we don't just fetch server's IP from IP header? */
1522 temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1524 bb_error_msg("no server ID, ignoring packet");
1526 /* still selecting - this server looks bad */
1528 /* it IS unaligned sometimes, don't "optimize" */
1529 move_from_unaligned32(server_addr, temp);
1530 /*xid = packet.xid; - already is */
1531 requested_ip = packet.yiaddr;
1533 /* enter requesting state */
1537 already_waited_sec = 0;
1542 case RENEW_REQUESTED:
1544 if (*message == DHCPACK) {
1545 temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1547 bb_error_msg("no lease time with ACK, using 1 hour lease");
1548 lease_seconds = 60 * 60;
1550 /* it IS unaligned sometimes, don't "optimize" */
1551 move_from_unaligned32(lease_seconds, temp);
1552 lease_seconds = ntohl(lease_seconds);
1553 lease_seconds &= 0x0fffffff; /* paranoia: must not be prone to overflows */
1554 if (lease_seconds < 10) /* and not too small */
1557 #if ENABLE_FEATURE_UDHCPC_ARPING
1559 /* RFC 2131 3.1 paragraph 5:
1560 * "The client receives the DHCPACK message with configuration
1561 * parameters. The client SHOULD perform a final check on the
1562 * parameters (e.g., ARP for allocated network address), and notes
1563 * the duration of the lease specified in the DHCPACK message. At this
1564 * point, the client is configured. If the client detects that the
1565 * address is already in use (e.g., through the use of ARP),
1566 * the client MUST send a DHCPDECLINE message to the server and restarts
1567 * the configuration process..." */
1568 if (!arpping(packet.yiaddr,
1571 client_config.client_mac,
1572 client_config.interface)
1574 bb_info_msg("Offered address is in use "
1575 "(got ARP reply), declining");
1576 send_decline(xid, server_addr, packet.yiaddr);
1578 if (state != REQUESTING)
1579 udhcp_run_script(NULL, "deconfig");
1580 change_listen_mode(LISTEN_RAW);
1581 state = INIT_SELECTING;
1582 client_config.first_secs = 0; /* make secs field count from 0 */
1584 timeout = tryagain_timeout;
1586 already_waited_sec = 0;
1587 continue; /* back to main loop */
1591 /* enter bound state */
1592 timeout = lease_seconds / 2;
1594 struct in_addr temp_addr;
1595 temp_addr.s_addr = packet.yiaddr;
1596 bb_info_msg("Lease of %s obtained, lease time %u",
1597 inet_ntoa(temp_addr), (unsigned)lease_seconds);
1599 requested_ip = packet.yiaddr;
1600 udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1603 change_listen_mode(LISTEN_NONE);
1604 if (opt & OPT_q) { /* quit after lease */
1605 if (opt & OPT_R) /* release on quit */
1606 perform_release(requested_ip, server_addr);
1609 /* future renew failures should not exit (JM) */
1611 #if BB_MMU /* NOMMU case backgrounded earlier */
1612 if (!(opt & OPT_f)) {
1613 client_background();
1614 /* do not background again! */
1615 opt = ((opt & ~OPT_b) | OPT_f);
1618 already_waited_sec = 0;
1619 continue; /* back to main loop */
1621 if (*message == DHCPNAK) {
1622 /* return to init state */
1623 bb_info_msg("Received DHCP NAK");
1624 udhcp_run_script(&packet, "nak");
1625 if (state != REQUESTING)
1626 udhcp_run_script(NULL, "deconfig");
1627 change_listen_mode(LISTEN_RAW);
1628 sleep(3); /* avoid excessive network traffic */
1629 state = INIT_SELECTING;
1630 client_config.first_secs = 0; /* make secs field count from 0 */
1634 already_waited_sec = 0;
1637 /* case BOUND: - ignore all packets */
1638 /* case RELEASED: - ignore all packets */
1640 /* back to main loop */
1641 } /* for (;;) - main loop ends */
1646 /*if (client_config.pidfile) - remove_pidfile has its own check */
1647 remove_pidfile(client_config.pidfile);