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 <asm/types.h>
29 #if (defined(__GLIBC__) && __GLIBC__ >= 2 && __GLIBC_MINOR__ >= 1) || defined(_NEWLIB_VERSION)
30 # include <netpacket/packet.h>
31 # include <net/ethernet.h>
33 # include <linux/if_packet.h>
34 # include <linux/if_ether.h>
36 #include <linux/filter.h>
38 /* "struct client_config_t client_config" is in bb_common_bufsiz1 */
41 static const char udhcpc_longopts
[] ALIGN1
=
42 "clientid-none\0" No_argument
"C"
43 "vendorclass\0" Required_argument
"V"
44 "hostname\0" Required_argument
"H"
45 "fqdn\0" Required_argument
"F"
46 "interface\0" Required_argument
"i"
47 "now\0" No_argument
"n"
48 "pidfile\0" Required_argument
"p"
49 "quit\0" No_argument
"q"
50 "release\0" No_argument
"R"
51 "request\0" Required_argument
"r"
52 "script\0" Required_argument
"s"
53 "timeout\0" Required_argument
"T"
54 "version\0" No_argument
"v"
55 "retries\0" Required_argument
"t"
56 "tryagain\0" Required_argument
"A"
57 "syslog\0" No_argument
"S"
58 "request-option\0" Required_argument
"O"
59 "no-default-options\0" No_argument
"o"
60 "foreground\0" No_argument
"f"
61 "background\0" No_argument
"b"
62 "broadcast\0" No_argument
"B"
63 IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument
"a")
64 IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument
"P")
67 /* Must match getopt32 option string order */
90 OPT_m
= 1 << 21, // zzz
91 /* The rest has variable bit positions, need to be clever */
93 USE_FOR_MMU( OPTBIT_b
,)
94 IF_FEATURE_UDHCPC_ARPING(OPTBIT_a
,)
95 IF_FEATURE_UDHCP_PORT( OPTBIT_P
,)
96 USE_FOR_MMU( OPT_b
= 1 << OPTBIT_b
,)
97 IF_FEATURE_UDHCPC_ARPING(OPT_a
= 1 << OPTBIT_a
,)
98 IF_FEATURE_UDHCP_PORT( OPT_P
= 1 << OPTBIT_P
,)
102 /*** Script execution code ***/
104 /* get a rough idea of how long an option will be (rounding up...) */
105 static const uint8_t len_of_option_as_string
[] = {
106 [OPTION_IP
] = sizeof("255.255.255.255 "),
107 [OPTION_IP_PAIR
] = sizeof("255.255.255.255 ") * 2,
108 [OPTION_STATIC_ROUTES
] = sizeof("255.255.255.255/32 255.255.255.255 "),
109 #if ENABLE_FEATURE_UDHCP_RFC5969
110 [OPTION_6RD
] = sizeof("32 128 FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF:FFFF 255.255.255.255 "),
112 [OPTION_STRING
] = 1,
113 [OPTION_STRING_HOST
] = 1,
114 #if ENABLE_FEATURE_UDHCP_RFC3397
115 [OPTION_DNS_STRING
] = 1, /* unused */
116 /* Hmmm, this severely overestimates size if SIP_SERVERS option
117 * is in domain name form: N-byte option in binary form
118 * mallocs ~16*N bytes. But it is freed almost at once.
120 [OPTION_SIP_SERVERS
] = sizeof("255.255.255.255 "),
122 // [OPTION_BOOLEAN ] = sizeof("yes "),
123 [OPTION_U8
] = sizeof("255 "),
124 [OPTION_U16
] = sizeof("65535 "),
125 // [OPTION_S16 ] = sizeof("-32768 "),
126 [OPTION_U32
] = sizeof("4294967295 "),
127 [OPTION_S32
] = sizeof("-2147483684 "),
130 /* note: ip is a pointer to an IP in network order, possibly misaliged */
131 static int sprint_nip(char *dest
, const char *pre
, const uint8_t *ip
)
133 return sprintf(dest
, "%s%u.%u.%u.%u", pre
, ip
[0], ip
[1], ip
[2], ip
[3]);
136 /* really simple implementation, just count the bits */
137 static int mton(uint32_t mask
)
140 mask
= ntohl(mask
); /* 111110000-like bit pattern */
148 /* Check if a given label represents a valid DNS label
149 * Return pointer to the first character after the label upon success,
153 /* We don't need to be particularly anal. For example, allowing _, hyphen
154 * at the end, or leading and trailing dots would be ok, since it
155 * can't be used for attacks. (Leading hyphen can be, if someone uses
157 * in the script: then hostname may be treated as an option)
159 static const char *valid_domain_label(const char *label
)
166 if ((ch
|0x20) < 'a' || (ch
|0x20) > 'z') {
168 /* label must begin with letter */
171 if (ch
< '0' || ch
> '9') {
172 if (ch
== '\0' || ch
== '.')
174 /* DNS allows only '-', but we are more permissive */
175 if (ch
!= '-' && ch
!= '_')
182 //if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
187 /* Check if a given name represents a valid DNS name */
188 /* See RFC1035, 2.3.1 */
189 static int good_hostname(const char *name
)
191 //const char *start = name;
194 name
= valid_domain_label(name
);
200 //return ((name - start) < 1025); /* NS_MAXDNAME */
205 /* Create "opt_name=opt_value" string */
206 static NOINLINE
char *xmalloc_optname_optval(uint8_t *option
, const struct dhcp_optflag
*optflag
, const char *opt_name
)
208 unsigned upper_length
;
209 int len
, type
, optlen
;
212 /* option points to OPT_DATA, need to go back to get OPT_LEN */
213 len
= option
[-OPT_DATA
+ OPT_LEN
];
215 type
= optflag
->flags
& OPTION_TYPE_MASK
;
216 optlen
= dhcp_option_lengths
[type
];
217 upper_length
= len_of_option_as_string
[type
]
218 * ((unsigned)(len
+ optlen
- 1) / (unsigned)optlen
);
220 dest
= ret
= xmalloc(upper_length
+ strlen(opt_name
) + 2);
221 dest
+= sprintf(ret
, "%s=", opt_name
);
223 while (len
>= optlen
) {
227 dest
+= sprint_nip(dest
, "", option
);
228 if (type
== OPTION_IP
)
230 dest
+= sprint_nip(dest
, "/", option
+ 4);
232 // case OPTION_BOOLEAN:
233 // dest += sprintf(dest, *option ? "yes" : "no");
236 dest
+= sprintf(dest
, "%u", *option
);
241 move_from_unaligned16(val_u16
, option
);
242 dest
+= sprintf(dest
, "%u", ntohs(val_u16
));
248 move_from_unaligned32(val_u32
, option
);
249 dest
+= sprintf(dest
, type
== OPTION_U32
? "%lu" : "%ld", (unsigned long) ntohl(val_u32
));
252 /* Note: options which use 'return' instead of 'break'
253 * (for example, OPTION_STRING) skip the code which handles
254 * the case of list of options.
257 case OPTION_STRING_HOST
:
258 memcpy(dest
, option
, len
);
260 if (type
== OPTION_STRING_HOST
&& !good_hostname(dest
))
261 safe_strncpy(dest
, "bad", len
);
263 case OPTION_STATIC_ROUTES
: {
264 /* Option binary format:
265 * mask [one byte, 0..32]
266 * ip [big endian, 0..4 bytes depending on mask]
267 * router [big endian, 4 bytes]
270 * We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
272 const char *pfx
= "";
274 while (len
>= 1 + 4) { /* mask + 0-byte ip + router */
287 bytes
= (mask
+ 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
288 while (--bytes
>= 0) {
296 dest
+= sprint_nip(dest
, pfx
, (void*) &nip
);
298 dest
+= sprintf(dest
, "/%u ", mask
);
300 dest
+= sprint_nip(dest
, "", option
);
308 /* Option binary format (see RFC 5969):
310 * 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
311 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
312 * | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
313 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
315 * ... (16 octets) ...
316 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
317 * ... 6rdBRIPv4Address(es) ...
318 * +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
319 * We convert it to a string
320 * "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
322 * Sanity check: ensure that our length is at least 22 bytes, that
324 * 6rdPrefixLen <= 128,
325 * 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
326 * (2nd condition need no check - it follows from 1st and 3rd).
327 * Else, return envvar with empty value ("optname=")
329 if (len
>= (1 + 1 + 16 + 4)
331 && (option
[1] + 32 - option
[0]) <= 128
334 dest
+= sprintf(dest
, "%u ", *option
++);
336 dest
+= sprintf(dest
, "%u ", *option
++);
338 dest
+= sprint_nip6(dest
, /* "", */ option
);
340 len
-= 1 + 1 + 16 + 4;
341 /* "+ 4" above corresponds to the length of IPv4 addr
342 * we consume in the loop below */
344 /* 6rdBRIPv4Address(es) */
345 dest
+= sprint_nip(dest
, " ", option
);
347 len
-= 4; /* do we have yet another 4+ bytes? */
354 #if ENABLE_FEATURE_UDHCP_RFC3397
355 case OPTION_DNS_STRING
:
356 /* unpack option into dest; use ret for prefix (i.e., "optname=") */
357 dest
= dname_dec(option
, len
, ret
);
362 /* error. return "optname=" string */
364 case OPTION_SIP_SERVERS
:
365 /* Option binary format:
367 * type=0: domain names, dns-compressed
372 if (option
[-1] == 0) {
373 dest
= dname_dec(option
, len
, ret
);
379 if (option
[-1] == 1) {
380 const char *pfx
= "";
385 dest
+= sprint_nip(dest
, pfx
, option
);
394 /* If we are here, try to format any remaining data
395 * in the option as another, similarly-formatted option
399 // TODO: it can be a list only if (optflag->flags & OPTION_LIST).
400 // Should we bail out/warn if we see multi-ip option which is
401 // not allowed to be such (for example, DHCP_BROADCAST)? -
402 if (len
< optlen
/* || !(optflag->flags & OPTION_LIST) */)
411 /* put all the parameters into the environment */
412 static char **fill_envp(struct dhcp_packet
*packet
)
417 const char *opt_name
;
419 uint8_t overload
= 0;
421 #define BITMAP unsigned
422 #define BBITS (sizeof(BITMAP) * 8)
423 #define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
424 #define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
425 BITMAP found_opts
[256 / BBITS
];
427 memset(found_opts
, 0, sizeof(found_opts
));
429 /* We need 6 elements for:
431 * "ip=N.N.N.N" from packet->yiaddr
432 * "siaddr=IP" from packet->siaddr_nip (unless 0)
433 * "boot_file=FILE" from packet->file (unless overloaded)
434 * "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
438 /* +1 element for each option, +2 for subnet option: */
440 /* note: do not search for "pad" (0) and "end" (255) options */
441 //TODO: change logic to scan packet _once_
442 for (i
= 1; i
< 255; i
++) {
443 temp
= udhcp_get_option(packet
, i
);
445 if (i
== DHCP_OPTION_OVERLOAD
)
447 else if (i
== DHCP_SUBNET
)
448 envc
++; /* for $mask */
450 /*if (i != DHCP_MESSAGE_TYPE)*/
451 FOUND_OPTS(i
) |= BMASK(i
);
455 curr
= envp
= xzalloc(sizeof(envp
[0]) * envc
);
457 *curr
= xasprintf("interface=%s", client_config
.interface
);
463 /* Export BOOTP fields. Fields we don't (yet?) export:
464 * uint8_t op; // always BOOTREPLY
465 * uint8_t htype; // hardware address type. 1 = 10mb ethernet
466 * uint8_t hlen; // hardware address length
467 * uint8_t hops; // used by relay agents only
469 * uint16_t secs; // elapsed since client began acquisition/renewal
470 * uint16_t flags; // only one flag so far: bcast. Never set by server
471 * uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
472 * // if during renew server wants to give us differn IP?)
473 * uint32_t gateway_nip; // relay agent IP address
474 * uint8_t chaddr[16]; // link-layer client hardware address (MAC)
475 * TODO: export gateway_nip as $giaddr?
477 /* Most important one: yiaddr as $ip */
478 *curr
= xmalloc(sizeof("ip=255.255.255.255"));
479 sprint_nip(*curr
, "ip=", (uint8_t *) &packet
->yiaddr
);
481 if (packet
->siaddr_nip
) {
482 /* IP address of next server to use in bootstrap */
483 *curr
= xmalloc(sizeof("siaddr=255.255.255.255"));
484 sprint_nip(*curr
, "siaddr=", (uint8_t *) &packet
->siaddr_nip
);
487 if (!(overload
& FILE_FIELD
) && packet
->file
[0]) {
488 /* watch out for invalid packets */
489 *curr
= xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR
"s", packet
->file
);
492 if (!(overload
& SNAME_FIELD
) && packet
->sname
[0]) {
493 /* watch out for invalid packets */
494 *curr
= xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR
"s", packet
->sname
);
498 /* Export known DHCP options */
499 opt_name
= dhcp_option_strings
;
502 uint8_t code
= dhcp_optflags
[i
].code
;
503 BITMAP
*found_ptr
= &FOUND_OPTS(code
);
504 BITMAP found_mask
= BMASK(code
);
505 if (!(*found_ptr
& found_mask
))
507 *found_ptr
&= ~found_mask
; /* leave only unknown options */
508 temp
= udhcp_get_option(packet
, code
);
509 *curr
= xmalloc_optname_optval(temp
, &dhcp_optflags
[i
], opt_name
);
511 if (code
== DHCP_SUBNET
) {
512 /* Subnet option: make things like "$ip/$mask" possible */
514 move_from_unaligned32(subnet
, temp
);
515 *curr
= xasprintf("mask=%u", mton(subnet
));
519 opt_name
+= strlen(opt_name
) + 1;
522 /* Export unknown options */
523 for (i
= 0; i
< 256;) {
524 BITMAP bitmap
= FOUND_OPTS(i
);
529 if (bitmap
& BMASK(i
)) {
532 temp
= udhcp_get_option(packet
, i
);
533 /* udhcp_get_option returns ptr to data portion,
534 * need to go back to get len
536 len
= temp
[-OPT_DATA
+ OPT_LEN
];
537 *curr
= xmalloc(sizeof("optNNN=") + 1 + len
*2);
538 ofs
= sprintf(*curr
, "opt%u=", i
);
539 *bin2hex(*curr
+ ofs
, (void*) temp
, len
) = '\0';
548 /* Call a script with a par file and env vars */
549 static void udhcp_run_script(struct dhcp_packet
*packet
, const char *name
)
554 envp
= fill_envp(packet
);
557 log1("Executing %s %s", client_config
.script
, name
);
558 argv
[0] = (char*) client_config
.script
;
559 argv
[1] = (char*) name
;
561 spawn_and_wait(argv
);
563 for (curr
= envp
; *curr
; curr
++) {
565 bb_unsetenv_and_free(*curr
);
571 /*** Sending/receiving packets ***/
573 static ALWAYS_INLINE
uint32_t random_xid(void)
578 /* Initialize the packet with the proper defaults */
579 static void init_packet(struct dhcp_packet
*packet
, char type
)
583 /* Fill in: op, htype, hlen, cookie fields; message type option: */
584 udhcp_init_header(packet
, type
);
586 packet
->xid
= random_xid();
588 client_config
.last_secs
= monotonic_sec();
589 if (client_config
.first_secs
== 0)
590 client_config
.first_secs
= client_config
.last_secs
;
591 secs
= client_config
.last_secs
- client_config
.first_secs
;
592 packet
->secs
= htons(secs
);
594 memcpy(packet
->chaddr
, client_config
.client_mac
, 6);
595 if (client_config
.clientid
)
596 udhcp_add_binary_option(packet
, client_config
.clientid
);
599 static void add_client_options(struct dhcp_packet
*packet
)
604 len
= sizeof(struct ip_udp_dhcp_packet
);
605 if (client_config
.client_mtu
== 0 ||
606 client_config
.client_mtu
> len
)
607 udhcp_add_simple_option(packet
, DHCP_MAX_SIZE
, htons(len
));
609 /* Add a "param req" option with the list of options we'd like to have
610 * from stubborn DHCP servers. Pull the data from the struct in common.c.
611 * No bounds checking because it goes towards the head of the packet. */
612 end
= udhcp_end_option(packet
->options
);
614 for (i
= 0; (c
= dhcp_optflags
[i
].code
) != 0; i
++) {
615 if (( (dhcp_optflags
[i
].flags
& OPTION_REQ
)
616 && !client_config
.no_default_options
618 || (client_config
.opt_mask
[c
>> 3] & (1 << (c
& 7)))
620 packet
->options
[end
+ OPT_DATA
+ len
] = c
;
625 packet
->options
[end
+ OPT_CODE
] = DHCP_PARAM_REQ
;
626 packet
->options
[end
+ OPT_LEN
] = len
;
627 packet
->options
[end
+ OPT_DATA
+ len
] = DHCP_END
;
630 if (client_config
.vendorclass
)
631 udhcp_add_binary_option(packet
, client_config
.vendorclass
);
632 if (client_config
.hostname
)
633 udhcp_add_binary_option(packet
, client_config
.hostname
);
634 if (client_config
.fqdn
)
635 udhcp_add_binary_option(packet
, client_config
.fqdn
);
637 /* Request broadcast replies if we have no IP addr */
638 if ((option_mask32
& OPT_B
) && packet
->ciaddr
== 0)
639 packet
->flags
|= htons(BROADCAST_FLAG
);
641 /* Request broadcast replies if we have no IP addr */
642 if ((option_mask32
& OPT_B
) && packet
->ciaddr
== 0)
643 packet
->flags
|= htons(BROADCAST_FLAG
);
645 /* Add -x options if any */
647 struct option_set
*curr
= client_config
.options
;
649 udhcp_add_binary_option(packet
, curr
->data
);
652 // if (client_config.sname)
653 // strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
654 // if (client_config.boot_file)
655 // strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
658 // This will be needed if we remove -V VENDOR_STR in favor of
659 // -x vendor:VENDOR_STR
660 //if (!udhcp_find_option(packet.options, DHCP_VENDOR))
661 // /* not set, set the default vendor ID */
662 // ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
666 * 4.4.4 Use of broadcast and unicast
668 * The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
669 * messages, unless the client knows the address of a DHCP server.
670 * The client unicasts DHCPRELEASE messages to the server. Because
671 * the client is declining the use of the IP address supplied by the server,
672 * the client broadcasts DHCPDECLINE messages.
674 * When the DHCP client knows the address of a DHCP server, in either
675 * INIT or REBOOTING state, the client may use that address
676 * in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
677 * The client may also use unicast to send DHCPINFORM messages
678 * to a known DHCP server. If the client receives no response to DHCP
679 * messages sent to the IP address of a known DHCP server, the DHCP
680 * client reverts to using the IP broadcast address.
683 static int raw_bcast_from_client_config_ifindex(struct dhcp_packet
*packet
)
685 return udhcp_send_raw_packet(packet
,
686 /*src*/ INADDR_ANY
, CLIENT_PORT
,
687 /*dst*/ INADDR_BROADCAST
, SERVER_PORT
, MAC_BCAST_ADDR
,
688 client_config
.ifindex
);
691 /* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
692 /* NOINLINE: limit stack usage in caller */
693 static NOINLINE
int send_discover(uint32_t xid
, uint32_t requested
)
695 struct dhcp_packet packet
;
698 /* Fill in: op, htype, hlen, cookie, chaddr fields,
699 * random xid field (we override it below),
700 * client-id option (unless -C), message type option:
702 init_packet(&packet
, DHCPDISCOVER
);
706 udhcp_add_simple_option(&packet
, DHCP_REQUESTED_IP
, requested
);
708 /* Add options: maxsize,
709 * optionally: hostname, fqdn, vendorclass,
710 * "param req" option according to -O, options specified with -x
712 add_client_options(&packet
);
715 bb_info_msg("Sending discover...");
716 return raw_bcast_from_client_config_ifindex(&packet
);
719 /* Broadcast a DHCP request message */
720 /* RFC 2131 3.1 paragraph 3:
721 * "The client _broadcasts_ a DHCPREQUEST message..."
723 /* NOINLINE: limit stack usage in caller */
724 static NOINLINE
int send_select(uint32_t xid
, uint32_t server
, uint32_t requested
)
726 struct dhcp_packet packet
;
730 * RFC 2131 4.3.2 DHCPREQUEST message
732 * If the DHCPREQUEST message contains a 'server identifier'
733 * option, the message is in response to a DHCPOFFER message.
734 * Otherwise, the message is a request to verify or extend an
735 * existing lease. If the client uses a 'client identifier'
736 * in a DHCPREQUEST message, it MUST use that same 'client identifier'
737 * in all subsequent messages. If the client included a list
738 * of requested parameters in a DHCPDISCOVER message, it MUST
739 * include that list in all subsequent messages.
741 /* Fill in: op, htype, hlen, cookie, chaddr fields,
742 * random xid field (we override it below),
743 * client-id option (unless -C), message type option:
745 init_packet(&packet
, DHCPREQUEST
);
748 udhcp_add_simple_option(&packet
, DHCP_REQUESTED_IP
, requested
);
750 udhcp_add_simple_option(&packet
, DHCP_SERVER_ID
, server
);
752 /* Add options: maxsize,
753 * optionally: hostname, fqdn, vendorclass,
754 * "param req" option according to -O, and options specified with -x
756 add_client_options(&packet
);
758 addr
.s_addr
= requested
;
759 bb_info_msg("Sending select for %s...", inet_ntoa(addr
));
760 return raw_bcast_from_client_config_ifindex(&packet
);
763 /* Unicast or broadcast a DHCP renew message */
764 /* NOINLINE: limit stack usage in caller */
765 static NOINLINE
int send_renew(uint32_t xid
, uint32_t server
, uint32_t ciaddr
)
767 struct dhcp_packet packet
;
770 * RFC 2131 4.3.2 DHCPREQUEST message
772 * DHCPREQUEST generated during RENEWING state:
774 * 'server identifier' MUST NOT be filled in, 'requested IP address'
775 * option MUST NOT be filled in, 'ciaddr' MUST be filled in with
776 * client's IP address. In this situation, the client is completely
777 * configured, and is trying to extend its lease. This message will
778 * be unicast, so no relay agents will be involved in its
779 * transmission. Because 'giaddr' is therefore not filled in, the
780 * DHCP server will trust the value in 'ciaddr', and use it when
781 * replying to the client.
783 /* Fill in: op, htype, hlen, cookie, chaddr fields,
784 * random xid field (we override it below),
785 * client-id option (unless -C), message type option:
787 init_packet(&packet
, DHCPREQUEST
);
790 packet
.ciaddr
= ciaddr
;
792 /* Add options: maxsize,
793 * optionally: hostname, fqdn, vendorclass,
794 * "param req" option according to -O, and options specified with -x
796 add_client_options(&packet
);
798 bb_info_msg("Sending renew...");
800 return udhcp_send_kernel_packet(&packet
,
802 server
, SERVER_PORT
);
803 return raw_bcast_from_client_config_ifindex(&packet
);
806 #if ENABLE_FEATURE_UDHCPC_ARPING
807 /* Broadcast a DHCP decline message */
808 /* NOINLINE: limit stack usage in caller */
809 static NOINLINE
int send_decline(/*uint32_t xid,*/ uint32_t server
, uint32_t requested
)
811 struct dhcp_packet packet
;
813 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
814 * client-id option (unless -C), message type option:
816 init_packet(&packet
, DHCPDECLINE
);
819 /* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
820 * but in case the server is buggy and wants DHCPDECLINE's xid
821 * to match the xid which started entire handshake,
822 * we use the same xid we used in initial DHCPDISCOVER:
826 /* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
827 udhcp_add_simple_option(&packet
, DHCP_REQUESTED_IP
, requested
);
829 udhcp_add_simple_option(&packet
, DHCP_SERVER_ID
, server
);
831 bb_info_msg("Sending decline...");
832 return raw_bcast_from_client_config_ifindex(&packet
);
836 /* Unicast a DHCP release message */
837 static int send_release(uint32_t server
, uint32_t ciaddr
)
839 struct dhcp_packet packet
;
841 /* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
842 * client-id option (unless -C), message type option:
844 init_packet(&packet
, DHCPRELEASE
);
846 /* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
847 packet
.ciaddr
= ciaddr
;
849 udhcp_add_simple_option(&packet
, DHCP_SERVER_ID
, server
);
851 bb_info_msg("Sending release...");
852 return udhcp_send_kernel_packet(&packet
, ciaddr
, CLIENT_PORT
, server
, SERVER_PORT
);
855 /* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
856 /* NOINLINE: limit stack usage in caller */
857 static NOINLINE
int udhcp_recv_raw_packet(struct dhcp_packet
*dhcp_pkt
, int fd
)
860 struct ip_udp_dhcp_packet packet
;
863 bytes
= safe_read(fd
, &packet
, sizeof(packet
));
865 log1("Packet read error, ignoring");
866 /* NB: possible down interface, etc. Caller should pause. */
867 return bytes
; /* returns -1 */
870 if (bytes
< (int) (sizeof(packet
.ip
) + sizeof(packet
.udp
))) {
871 log1("Packet is too short, ignoring");
875 if (bytes
< ntohs(packet
.ip
.tot_len
)) {
876 /* packet is bigger than sizeof(packet), we did partial read */
877 log1("Oversized packet, ignoring");
881 /* ignore any extra garbage bytes */
882 bytes
= ntohs(packet
.ip
.tot_len
);
884 /* make sure its the right packet for us, and that it passes sanity checks */
885 if (packet
.ip
.protocol
!= IPPROTO_UDP
886 || packet
.ip
.version
!= IPVERSION
887 || packet
.ip
.ihl
!= (sizeof(packet
.ip
) >> 2)
888 || packet
.udp
.dest
!= htons(CLIENT_PORT
)
889 /* || bytes > (int) sizeof(packet) - can't happen */
890 || ntohs(packet
.udp
.len
) != (uint16_t)(bytes
- sizeof(packet
.ip
))
892 log1("Unrelated/bogus packet, ignoring");
896 /* verify IP checksum */
897 check
= packet
.ip
.check
;
899 if (check
!= inet_cksum((uint16_t *)&packet
.ip
, sizeof(packet
.ip
))) {
900 log1("Bad IP header checksum, ignoring");
904 /* verify UDP checksum. IP header has to be modified for this */
905 memset(&packet
.ip
, 0, offsetof(struct iphdr
, protocol
));
906 /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
907 packet
.ip
.tot_len
= packet
.udp
.len
; /* yes, this is needed */
908 check
= packet
.udp
.check
;
909 packet
.udp
.check
= 0;
910 if (check
&& check
!= inet_cksum((uint16_t *)&packet
, bytes
)) {
911 log1("Packet with bad UDP checksum received, ignoring");
915 if (packet
.data
.cookie
!= htonl(DHCP_MAGIC
)) {
916 bb_info_msg("Packet with bad magic, ignoring");
920 log1("Received a packet");
921 udhcp_dump_packet(&packet
.data
);
923 bytes
-= sizeof(packet
.ip
) + sizeof(packet
.udp
);
924 memcpy(dhcp_pkt
, &packet
.data
, bytes
);
931 static int sockfd
= -1;
933 #define LISTEN_NONE 0
934 #define LISTEN_KERNEL 1
936 static smallint listen_mode
;
938 /* initial state: (re)start DHCP negotiation */
939 #define INIT_SELECTING 0
940 /* discover was sent, DHCPOFFER reply received */
942 /* select/renew was sent, DHCPACK reply received */
944 /* half of lease passed, want to renew it by sending unicast renew requests */
946 /* renew requests were not answered, lease is almost over, send broadcast renew */
948 /* manually requested renew (SIGUSR1) */
949 #define RENEW_REQUESTED 5
950 /* release, possibly manually requested (SIGUSR2) */
952 static smallint state
;
954 static int udhcp_raw_socket(int ifindex
)
957 struct sockaddr_ll sock
;
962 * I've selected not to see LL header, so BPF doesn't see it, too.
963 * The filter may also pass non-IP and non-ARP packets, but we do
964 * a more complete check when receiving the message in userspace.
966 * and filter shamelessly stolen from:
968 * http://www.flamewarmaster.de/software/dhcpclient/
970 * There are a few other interesting ideas on that page (look under
971 * "Motivation"). Use of netlink events is most interesting. Think
972 * of various network servers listening for events and reconfiguring.
973 * That would obsolete sending HUP signals and/or make use of restarts.
975 * Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
978 * TODO: make conditional?
980 static const struct sock_filter filter_instr
[] = {
981 /* load 9th byte (protocol) */
982 BPF_STMT(BPF_LD
|BPF_B
|BPF_ABS
, 9),
983 /* jump to L1 if it is IPPROTO_UDP, else to L4 */
984 BPF_JUMP(BPF_JMP
|BPF_JEQ
|BPF_K
, IPPROTO_UDP
, 0, 6),
985 /* L1: load halfword from offset 6 (flags and frag offset) */
986 BPF_STMT(BPF_LD
|BPF_H
|BPF_ABS
, 6),
987 /* jump to L4 if any bits in frag offset field are set, else to L2 */
988 BPF_JUMP(BPF_JMP
|BPF_JSET
|BPF_K
, 0x1fff, 4, 0),
989 /* L2: skip IP header (load index reg with header len) */
990 BPF_STMT(BPF_LDX
|BPF_B
|BPF_MSH
, 0),
991 /* load udp destination port from halfword[header_len + 2] */
992 BPF_STMT(BPF_LD
|BPF_H
|BPF_IND
, 2),
993 /* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
994 BPF_JUMP(BPF_JMP
|BPF_JEQ
|BPF_K
, 68, 0, 1),
995 /* L3: accept packet */
996 BPF_STMT(BPF_RET
|BPF_K
, 0xffffffff),
997 /* L4: discard packet */
998 BPF_STMT(BPF_RET
|BPF_K
, 0),
1000 static const struct sock_fprog filter_prog
= {
1001 .len
= sizeof(filter_instr
) / sizeof(filter_instr
[0]),
1002 /* casting const away: */
1003 .filter
= (struct sock_filter
*) filter_instr
,
1006 log1("Opening raw socket on ifindex %d", ifindex
); //log2?
1008 fd
= xsocket(PF_PACKET
, SOCK_DGRAM
, htons(ETH_P_IP
));
1009 log1("Got raw socket fd %d", fd
); //log2?
1011 sock
.sll_family
= AF_PACKET
;
1012 sock
.sll_protocol
= htons(ETH_P_IP
);
1013 sock
.sll_ifindex
= ifindex
;
1014 xbind(fd
, (struct sockaddr
*) &sock
, sizeof(sock
));
1016 if (CLIENT_PORT
== 68) {
1017 /* Use only if standard port is in use */
1018 /* Ignoring error (kernel may lack support for this) */
1019 if (setsockopt(fd
, SOL_SOCKET
, SO_ATTACH_FILTER
, &filter_prog
,
1020 sizeof(filter_prog
)) >= 0)
1021 log1("Attached filter to raw socket fd %d", fd
); // log?
1024 log1("Created raw socket");
1029 static void change_listen_mode(int new_mode
)
1031 log1("Entering listen mode: %s",
1032 new_mode
!= LISTEN_NONE
1033 ? (new_mode
== LISTEN_KERNEL
? "kernel" : "raw")
1037 listen_mode
= new_mode
;
1042 if (new_mode
== LISTEN_KERNEL
)
1043 sockfd
= udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT
, client_config
.interface
);
1044 else if (new_mode
!= LISTEN_NONE
)
1045 sockfd
= udhcp_raw_socket(client_config
.ifindex
);
1046 /* else LISTEN_NONE: sockfd stays closed */
1049 /* Called only on SIGUSR1 */
1050 static void perform_renew(void)
1052 bb_info_msg("Performing a DHCP renew");
1055 change_listen_mode(LISTEN_RAW
); // zzz
1058 // state = RENEW_REQUESTED; // zzz
1060 case RENEW_REQUESTED
: /* impatient are we? fine, square 1 */
1063 change_listen_mode(LISTEN_RAW
);
1064 state
= INIT_SELECTING
;
1066 case INIT_SELECTING
:
1071 static void perform_release(uint32_t server_addr
, uint32_t requested_ip
)
1073 char buffer
[sizeof("255.255.255.255")];
1074 struct in_addr temp_addr
;
1076 /* send release packet */
1077 if (state
== BOUND
|| state
== RENEWING
|| state
== REBINDING
) {
1078 temp_addr
.s_addr
= server_addr
;
1079 strcpy(buffer
, inet_ntoa(temp_addr
));
1080 temp_addr
.s_addr
= requested_ip
;
1081 bb_info_msg("Unicasting a release of %s to %s",
1082 inet_ntoa(temp_addr
), buffer
);
1083 send_release(server_addr
, requested_ip
); /* unicast */
1084 udhcp_run_script(NULL
, "deconfig");
1086 bb_info_msg("Entering released state");
1088 change_listen_mode(LISTEN_NONE
);
1092 static uint8_t* alloc_dhcp_option(int code
, const char *str
, int extra
)
1095 int len
= strnlen(str
, 255);
1096 storage
= xzalloc(len
+ extra
+ OPT_DATA
);
1097 storage
[OPT_CODE
] = code
;
1098 storage
[OPT_LEN
] = len
+ extra
;
1099 memcpy(storage
+ extra
+ OPT_DATA
, str
, len
);
1104 static void client_background(void)
1107 logmode
&= ~LOGMODE_STDIO
;
1108 /* rewrite pidfile, as our pid is different now */
1109 write_pidfile(client_config
.pidfile
);
1113 //usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1114 //usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1116 //usage:# define IF_UDHCP_VERBOSE(...)
1118 //usage:#define udhcpc_trivial_usage
1119 //usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oCRB] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
1120 //usage: " [-V VENDOR] [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
1121 //usage:#define udhcpc_full_usage "\n"
1122 //usage: IF_LONG_OPTS(
1123 //usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1124 //usage: "\n -p,--pidfile FILE Create pidfile"
1125 //usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1126 //usage: "\n -B,--broadcast Request broadcast replies"
1127 //usage: "\n -t,--retries N Send up to N discover packets"
1128 //usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
1129 //usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
1130 //usage: "\n -f,--foreground Run in foreground"
1131 //usage: USE_FOR_MMU(
1132 //usage: "\n -b,--background Background if lease is not obtained"
1134 //usage: "\n -n,--now Exit if lease is not obtained"
1135 //usage: "\n -q,--quit Exit after obtaining lease"
1136 //usage: "\n -R,--release Release IP on exit"
1137 //usage: "\n -S,--syslog Log to syslog too"
1138 //usage: IF_FEATURE_UDHCP_PORT(
1139 //usage: "\n -P,--client-port N Use port N (default 68)"
1141 //usage: IF_FEATURE_UDHCPC_ARPING(
1142 //usage: "\n -a,--arping Use arping to validate offered address"
1144 //usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1145 //usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1146 //usage: "\n -r,--request IP Request this IP address"
1147 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1148 //usage: "\n Examples of string, numeric, and hex byte opts:"
1149 //usage: "\n -x hostname:bbox - option 12"
1150 //usage: "\n -x lease:3600 - option 51 (lease time)"
1151 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1152 //usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1153 //usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1154 //usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1155 //usage: IF_UDHCP_VERBOSE(
1156 //usage: "\n -v Verbose"
1159 //usage: IF_NOT_LONG_OPTS(
1160 //usage: "\n -i IFACE Interface to use (default eth0)"
1161 //usage: "\n -p FILE Create pidfile"
1162 //usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1163 //usage: "\n -B Request broadcast replies"
1164 //usage: "\n -t N Send up to N discover packets"
1165 //usage: "\n -T N Pause between packets (default 3 seconds)"
1166 //usage: "\n -A N Wait N seconds (default 20) after failure"
1167 //usage: "\n -f Run in foreground"
1168 //usage: USE_FOR_MMU(
1169 //usage: "\n -b Background if lease is not obtained"
1171 //usage: "\n -n Exit if lease is not obtained"
1172 //usage: "\n -q Exit after obtaining lease"
1173 //usage: "\n -R Release IP on exit"
1174 //usage: "\n -S Log to syslog too"
1175 //usage: IF_FEATURE_UDHCP_PORT(
1176 //usage: "\n -P N Use port N (default 68)"
1178 //usage: IF_FEATURE_UDHCPC_ARPING(
1179 //usage: "\n -a Use arping to validate offered address"
1181 //usage: "\n -O OPT Request option OPT from server (cumulative)"
1182 //usage: "\n -o Don't request any options (unless -O is given)"
1183 //usage: "\n -r IP Request this IP address"
1184 //usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1185 //usage: "\n Examples of string, numeric, and hex byte opts:"
1186 //usage: "\n -x hostname:bbox - option 12"
1187 //usage: "\n -x lease:3600 - option 51 (lease time)"
1188 //usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1189 //usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1190 //usage: "\n -H,-h NAME Send NAME as client hostname (default none)"
1191 //usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1192 //usage: "\n -C Don't send MAC as client identifier"
1193 //usage: IF_UDHCP_VERBOSE(
1194 //usage: "\n -v Verbose"
1197 //usage: "\nSignals:"
1198 //usage: "\n USR1 Renew current lease"
1199 //usage: "\n USR2 Release current lease"
1202 int udhcpc_main(int argc
, char **argv
) MAIN_EXTERNALLY_VISIBLE
;
1203 int udhcpc_main(int argc UNUSED_PARAM
, char **argv
)
1205 uint8_t *temp
, *message
;
1206 const char *str_V
, *str_h
, *str_F
, *str_r
;
1207 IF_FEATURE_UDHCP_PORT(char *str_P
;)
1208 void *clientid_mac_ptr
;
1209 llist_t
*list_O
= NULL
;
1210 llist_t
*list_x
= NULL
;
1211 int tryagain_timeout
= 20;
1212 int discover_timeout
= 3;
1213 int discover_retries
= 5;
1214 uint32_t server_addr
= server_addr
; /* for compiler */
1215 uint32_t requested_ip
= 0;
1216 uint32_t xid
= xid
; /* for compiler */
1218 int timeout
; /* must be signed */
1219 unsigned already_waited_sec
;
1225 /* Default options */
1226 IF_FEATURE_UDHCP_PORT(SERVER_PORT
= 67;)
1227 IF_FEATURE_UDHCP_PORT(CLIENT_PORT
= 68;)
1228 client_config
.interface
= "eth0";
1229 client_config
.script
= CONFIG_UDHCPC_DEFAULT_SCRIPT
;
1230 str_V
= "udhcp "BB_VER
;
1232 /* Parse command line */
1233 /* O,x: list; -T,-t,-A take numeric param */
1234 opt_complementary
= "O::x::T+:t+:A+" IF_UDHCP_VERBOSE(":vv") ;
1236 IF_LONG_OPTS(applet_long_options
= udhcpc_longopts
;)
1237 opt
= getopt32(argv
, "CV:H:h:F:i:np:qRr:s:T:t:SA:O:ox:fB"
1240 IF_FEATURE_UDHCPC_ARPING("a")
1241 IF_FEATURE_UDHCP_PORT("P:")
1243 , &str_V
, &str_h
, &str_h
, &str_F
1244 , &client_config
.interface
, &client_config
.pidfile
, &str_r
/* i,p */
1245 , &client_config
.script
/* s */
1246 , &discover_timeout
, &discover_retries
, &tryagain_timeout
/* T,t,A */
1249 IF_FEATURE_UDHCP_PORT(, &str_P
)
1250 IF_UDHCP_VERBOSE(, &dhcp_verbose
)
1252 if (opt
& (OPT_h
|OPT_H
)) {
1254 bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1255 client_config
.hostname
= alloc_dhcp_option(DHCP_HOST_NAME
, str_h
, 0);
1258 /* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1259 client_config
.fqdn
= alloc_dhcp_option(DHCP_FQDN
, str_F
, 3);
1260 /* Flag bits: 0000NEOS
1261 * S: 1 = Client requests server to update A RR in DNS as well as PTR
1262 * O: 1 = Server indicates to client that DNS has been updated regardless
1263 * E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1264 * not "host.domain.com". Format 0 is obsolete.
1265 * N: 1 = Client requests server to not update DNS (S must be 0 then)
1266 * Two [0] bytes which follow are deprecated and must be 0.
1268 client_config
.fqdn
[OPT_DATA
+ 0] = 0x1;
1269 /*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1270 /*client_config.fqdn[OPT_DATA + 2] = 0; */
1273 requested_ip
= inet_addr(str_r
);
1274 #if ENABLE_FEATURE_UDHCP_PORT
1276 CLIENT_PORT
= xatou16(str_P
);
1277 SERVER_PORT
= CLIENT_PORT
- 1;
1281 client_config
.no_default_options
= 1;
1283 char *optstr
= llist_pop(&list_O
);
1284 unsigned n
= bb_strtou(optstr
, NULL
, 0);
1285 if (errno
|| n
> 254) {
1286 n
= udhcp_option_idx(optstr
);
1287 n
= dhcp_optflags
[n
].code
;
1289 client_config
.opt_mask
[n
>> 3] |= 1 << (n
& 7);
1292 char *optstr
= llist_pop(&list_x
);
1293 char *colon
= strchr(optstr
, ':');
1296 /* now it looks similar to udhcpd's config file line:
1297 * "optname optval", using the common routine: */
1298 udhcp_str2optset(optstr
, &client_config
.options
);
1301 if (opt
& OPT_m
) // zzz
1304 if (udhcp_read_interface(client_config
.interface
,
1305 &client_config
.ifindex
,
1307 client_config
.client_mac
,
1308 &client_config
.client_mtu
)
1313 clientid_mac_ptr
= NULL
;
1314 if (!(opt
& OPT_C
) && !udhcp_find_option(client_config
.options
, DHCP_CLIENT_ID
)) {
1315 /* not suppressed and not set, set the default client ID */
1316 client_config
.clientid
= alloc_dhcp_option(DHCP_CLIENT_ID
, "", 7);
1317 client_config
.clientid
[OPT_DATA
] = 1; /* type: ethernet */
1318 clientid_mac_ptr
= client_config
.clientid
+ OPT_DATA
+1;
1319 memcpy(clientid_mac_ptr
, client_config
.client_mac
, 6);
1321 if (str_V
[0] != '\0') {
1322 // can drop -V, str_V, client_config.vendorclass,
1323 // but need to add "vendor" to the list of recognized
1324 // string opts for this to work;
1325 // and need to tweak add_client_options() too...
1326 // ...so the question is, should we?
1327 //bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1328 client_config
.vendorclass
= alloc_dhcp_option(DHCP_VENDOR
, str_V
, 0);
1332 /* on NOMMU reexec (i.e., background) early */
1333 if (!(opt
& OPT_f
)) {
1334 bb_daemonize_or_rexec(0 /* flags */, argv
);
1335 logmode
= LOGMODE_NONE
;
1339 openlog(applet_name
, LOG_PID
, LOG_DAEMON
);
1340 logmode
|= LOGMODE_SYSLOG
;
1343 /* Make sure fd 0,1,2 are open */
1344 bb_sanitize_stdio();
1345 /* Equivalent of doing a fflush after every \n */
1347 /* Create pidfile */
1348 write_pidfile(client_config
.pidfile
);
1349 /* Goes to stdout (unless NOMMU) and possibly syslog */
1350 bb_info_msg("%s (v"BB_VER
") started", applet_name
);
1351 /* Set up the signal pipe */
1353 /* We want random_xid to be random... */
1354 srand(monotonic_us());
1356 state
= INIT_SELECTING
;
1357 udhcp_run_script(NULL
, "deconfig");
1358 change_listen_mode(LISTEN_RAW
);
1361 already_waited_sec
= 0;
1363 /* Main event loop. select() waits on signal pipe and possibly
1365 * "continue" statements in code below jump to the top of the loop.
1369 struct dhcp_packet packet
;
1370 /* silence "uninitialized!" warning */
1371 unsigned timestamp_before_wait
= timestamp_before_wait
;
1373 //bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1375 /* Was opening raw or udp socket here
1376 * if (listen_mode != LISTEN_NONE && sockfd < 0),
1377 * but on fast network renew responses return faster
1378 * than we open sockets. Thus this code is moved
1379 * to change_listen_mode(). Thus we open listen socket
1380 * BEFORE we send renew request (see "case BOUND:"). */
1382 max_fd
= udhcp_sp_fd_set(&rfds
, sockfd
);
1384 tv
.tv_sec
= timeout
- already_waited_sec
;
1387 /* If we already timed out, fall through with retval = 0, else... */
1388 if ((int)tv
.tv_sec
> 0) {
1389 timestamp_before_wait
= (unsigned)monotonic_sec();
1390 log1("Waiting on select...");
1391 retval
= select(max_fd
+ 1, &rfds
, NULL
, NULL
, &tv
);
1393 /* EINTR? A signal was caught, don't panic */
1394 if (errno
== EINTR
) {
1395 already_waited_sec
+= (unsigned)monotonic_sec() - timestamp_before_wait
;
1398 /* Else: an error occured, panic! */
1399 bb_perror_msg_and_die("select");
1403 /* If timeout dropped to zero, time to become active:
1404 * resend discover/renew/whatever
1407 /* When running on a bridge, the ifindex may have changed
1408 * (e.g. if member interfaces were added/removed
1409 * or if the status of the bridge changed).
1410 * Refresh ifindex and client_mac:
1412 if (udhcp_read_interface(client_config
.interface
,
1413 &client_config
.ifindex
,
1415 client_config
.client_mac
,
1416 &client_config
.client_mtu
)
1418 goto ret0
; /* iface is gone? */
1420 if (clientid_mac_ptr
)
1421 memcpy(clientid_mac_ptr
, client_config
.client_mac
, 6);
1423 /* We will restart the wait in any case */
1424 already_waited_sec
= 0;
1427 case INIT_SELECTING
:
1428 if (packet_num
< discover_retries
) {
1429 if (packet_num
== 0)
1432 send_discover(xid
, requested_ip
);
1433 timeout
= discover_timeout
;
1438 udhcp_run_script(NULL
, "leasefail");
1439 #if BB_MMU /* -b is not supported on NOMMU */
1440 if (opt
& OPT_b
) { /* background if no lease */
1441 bb_info_msg("No lease, forking to background");
1442 client_background();
1443 /* do not background again! */
1444 opt
= ((opt
& ~OPT_b
) | OPT_f
);
1447 if (opt
& OPT_n
) { /* abort if no lease */
1448 bb_info_msg("No lease, failing");
1452 /* wait before trying again */
1453 timeout
= tryagain_timeout
;
1457 if (packet_num
< discover_retries
) {
1458 /* send broadcast select packet */
1459 send_select(xid
, server_addr
, requested_ip
);
1460 timeout
= discover_timeout
;
1464 /* Timed out, go back to init state.
1465 * "discover...select...discover..." loops
1466 * were seen in the wild. Treat them similarly
1467 * to "no response to discover" case */
1468 change_listen_mode(LISTEN_RAW
);
1469 state
= INIT_SELECTING
;
1472 /* 1/2 lease passed, enter renewing state */
1474 client_config
.first_secs
= 0; /* make secs field count from 0 */
1475 change_listen_mode(LISTEN_RAW
); // was: LISTEN_KERNEL -- zzz
1476 log1("Entering renew state");
1477 /* fall right through */
1478 case RENEW_REQUESTED
: /* manual (SIGUSR1) renew */
1479 case_RENEW_REQUESTED
:
1482 /* send an unicast renew request */
1483 /* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1484 * a new UDP socket for sending inside send_renew.
1485 * I hazard to guess existing listening socket
1486 * is somehow conflicting with it, but why is it
1487 * not deterministic then?! Strange.
1488 * Anyway, it does recover by eventually failing through
1489 * into INIT_SELECTING state.
1491 send_renew(xid
, server_addr
, requested_ip
);
1495 /* Timed out, enter rebinding state */
1496 log1("Entering rebinding state");
1498 /* fall right through */
1500 /* Switch to bcast receive */
1501 change_listen_mode(LISTEN_RAW
);
1502 /* Lease is *really* about to run out,
1503 * try to find DHCP server using broadcast */
1505 /* send a broadcast renew request */
1506 send_renew(xid
, 0 /*INADDR_ANY*/, requested_ip
);
1510 /* Timed out, enter init state */
1511 bb_info_msg("Lease lost, entering init state");
1512 udhcp_run_script(NULL
, "deconfig");
1513 state
= INIT_SELECTING
;
1514 client_config
.first_secs
= 0; /* make secs field count from 0 */
1515 /*timeout = 0; - already is */
1518 /* case RELEASED: */
1520 /* yah, I know, *you* say it would never happen */
1522 continue; /* back to main loop */
1523 } /* if select timed out */
1525 /* select() didn't timeout, something happened */
1527 /* Is it a signal? */
1528 /* note: udhcp_sp_read checks FD_ISSET before reading */
1529 switch (udhcp_sp_read(&rfds
)) {
1531 client_config
.first_secs
= 0; /* make secs field count from 0 */
1532 already_waited_sec
= 0;
1534 if (state
== RENEW_REQUESTED
)
1535 if (timeout
> tryagain_timeout
)
1536 timeout
= tryagain_timeout
;
1537 goto case_RENEW_REQUESTED
;
1538 /* Start things over */
1540 /* Kill any timeouts, user wants this to hurry along */
1544 perform_release(server_addr
, requested_ip
);
1548 bb_info_msg("Received SIGTERM");
1552 /* Is it a packet? */
1553 if (listen_mode
== LISTEN_NONE
|| !FD_ISSET(sockfd
, &rfds
))
1559 /* A packet is ready, read it */
1560 if (listen_mode
== LISTEN_KERNEL
)
1561 len
= udhcp_recv_kernel_packet(&packet
, sockfd
);
1563 len
= udhcp_recv_raw_packet(&packet
, sockfd
);
1565 /* Error is severe, reopen socket */
1566 bb_info_msg("Read error: %s, reopening socket", strerror(errno
));
1567 sleep(discover_timeout
); /* 3 seconds by default */
1568 change_listen_mode(listen_mode
); /* just close and reopen */
1570 /* If this packet will turn out to be unrelated/bogus,
1571 * we will go back and wait for next one.
1572 * Be sure timeout is properly decreased. */
1573 already_waited_sec
+= (unsigned)monotonic_sec() - timestamp_before_wait
;
1578 if (packet
.xid
!= xid
) {
1579 log1("xid %x (our is %x), ignoring packet",
1580 (unsigned)packet
.xid
, (unsigned)xid
);
1584 /* Ignore packets that aren't for us */
1585 if (packet
.hlen
!= 6
1586 || memcmp(packet
.chaddr
, client_config
.client_mac
, 6) != 0
1588 //FIXME: need to also check that last 10 bytes are zero
1589 log1("chaddr does not match, ignoring packet"); // log2?
1593 message
= udhcp_get_option(&packet
, DHCP_MESSAGE_TYPE
);
1594 if (message
== NULL
) {
1595 bb_error_msg("no message type option, ignoring packet");
1600 case INIT_SELECTING
:
1601 /* Must be a DHCPOFFER */
1602 if (*message
== DHCPOFFER
) {
1603 /* What exactly is server's IP? There are several values.
1604 * Example DHCP offer captured with tchdump:
1606 * 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1608 * Your-IP 10.34.25.202
1609 * Server-IP 10.34.32.125 // "next server" IP
1610 * Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1612 * DHCP-Message Option 53, length 1: Offer
1613 * Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1614 * Default-Gateway Option 3, length 4: 10.34.25.254 // router
1616 * We think that real server IP (one to use in renew/release)
1617 * is one in Server-ID option. But I am not 100% sure.
1618 * IP header's src and Gateway-IP (same in this example)
1620 * "Next server" and router are definitely wrong ones to use, though...
1622 temp
= udhcp_get_option(&packet
, DHCP_SERVER_ID
);
1624 bb_error_msg("no server ID, ignoring packet");
1626 /* still selecting - this server looks bad */
1628 /* it IS unaligned sometimes, don't "optimize" */
1629 move_from_unaligned32(server_addr
, temp
);
1630 /*xid = packet.xid; - already is */
1631 requested_ip
= packet
.yiaddr
;
1633 /* enter requesting state */
1637 already_waited_sec
= 0;
1642 case RENEW_REQUESTED
:
1644 if (*message
== DHCPACK
) {
1645 uint32_t lease_seconds
;
1646 struct in_addr temp_addr
;
1648 temp
= udhcp_get_option(&packet
, DHCP_LEASE_TIME
);
1650 bb_error_msg("no lease time with ACK, using 1 hour lease");
1651 lease_seconds
= 60 * 60;
1653 /* it IS unaligned sometimes, don't "optimize" */
1654 move_from_unaligned32(lease_seconds
, temp
);
1655 lease_seconds
= ntohl(lease_seconds
);
1656 /* paranoia: must not be too small and not prone to overflows */
1657 if (lease_seconds
< 0x10)
1658 lease_seconds
= 0x10;
1659 if (lease_seconds
>= 0x10000000)
1660 lease_seconds
= 0x0fffffff;
1662 #if ENABLE_FEATURE_UDHCPC_ARPING
1664 /* RFC 2131 3.1 paragraph 5:
1665 * "The client receives the DHCPACK message with configuration
1666 * parameters. The client SHOULD perform a final check on the
1667 * parameters (e.g., ARP for allocated network address), and notes
1668 * the duration of the lease specified in the DHCPACK message. At this
1669 * point, the client is configured. If the client detects that the
1670 * address is already in use (e.g., through the use of ARP),
1671 * the client MUST send a DHCPDECLINE message to the server and restarts
1672 * the configuration process..." */
1673 if (!arpping(packet
.yiaddr
,
1676 client_config
.client_mac
,
1677 client_config
.interface
)
1679 bb_info_msg("Offered address is in use "
1680 "(got ARP reply), declining");
1681 send_decline(/*xid,*/ server_addr
, packet
.yiaddr
);
1683 if (state
!= REQUESTING
)
1684 udhcp_run_script(NULL
, "deconfig");
1685 change_listen_mode(LISTEN_RAW
);
1686 state
= INIT_SELECTING
;
1687 client_config
.first_secs
= 0; /* make secs field count from 0 */
1689 timeout
= tryagain_timeout
;
1691 already_waited_sec
= 0;
1692 continue; /* back to main loop */
1696 /* enter bound state */
1697 timeout
= lease_seconds
/ 2;
1698 temp_addr
.s_addr
= packet
.yiaddr
;
1699 bb_info_msg("Lease of %s obtained, lease time %u",
1700 inet_ntoa(temp_addr
), (unsigned)lease_seconds
);
1701 requested_ip
= packet
.yiaddr
;
1702 udhcp_run_script(&packet
, state
== REQUESTING
? "bound" : "renew");
1705 change_listen_mode(LISTEN_NONE
);
1706 if (opt
& OPT_q
) { /* quit after lease */
1709 /* future renew failures should not exit (JM) */
1711 #if BB_MMU /* NOMMU case backgrounded earlier */
1712 if (!(opt
& OPT_f
)) {
1713 client_background();
1714 /* do not background again! */
1715 opt
= ((opt
& ~OPT_b
) | OPT_f
);
1718 /* make future renew packets use different xid */
1719 /* xid = random_xid(); ...but why bother? */
1720 already_waited_sec
= 0;
1721 continue; /* back to main loop */
1723 if (*message
== DHCPNAK
) {
1724 /* return to init state */
1725 bb_info_msg("Received DHCP NAK");
1726 udhcp_run_script(&packet
, "nak");
1727 if (state
!= REQUESTING
)
1728 udhcp_run_script(NULL
, "deconfig");
1729 change_listen_mode(LISTEN_RAW
);
1730 sleep(3); /* avoid excessive network traffic */
1731 state
= INIT_SELECTING
;
1732 client_config
.first_secs
= 0; /* make secs field count from 0 */
1736 already_waited_sec
= 0;
1739 /* case BOUND: - ignore all packets */
1740 /* case RELEASED: - ignore all packets */
1742 /* back to main loop */
1743 } /* for (;;) - main loop ends */
1746 if (opt
& OPT_R
) /* release on quit */
1747 perform_release(server_addr
, requested_ip
);
1750 /*if (client_config.pidfile) - remove_pidfile has its own check */
1751 remove_pidfile(client_config
.pidfile
);