path: root/networking/udhcp/dhcpc.c (plain)
blob: 0e236261bad963a58d00a994f4825d55576b2c42

1	/* vi: set sw=4 ts=4: */
2	/*
3	* udhcp client
4	*
5	* Russ Dill <Russ.Dill@asu.edu> July 2001
6	*
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.
11	*
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.
16	*
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.
20	*/
21	//applet:IF_UDHCPC(APPLET(udhcpc, BB_DIR_SBIN, BB_SUID_DROP))
22
23	//kbuild:lib-$(CONFIG_UDHCPC) += common.o packet.o signalpipe.o socket.o
24	//kbuild:lib-$(CONFIG_UDHCPC) += dhcpc.o
25	//kbuild:lib-$(CONFIG_FEATURE_UDHCPC_ARPING) += arpping.o
26	//kbuild:lib-$(CONFIG_FEATURE_UDHCP_RFC3397) += domain_codec.o
27
28	#include <syslog.h>
29	/* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
30	#define WANT_PIDFILE 1
31	#include "common.h"
32	#include "dhcpd.h"
33	#include "dhcpc.h"
34
35	#include <netinet/if_ether.h>
36	#include <linux/filter.h>
37	#include <linux/if_packet.h>
38
39	#ifndef PACKET_AUXDATA
40	# define PACKET_AUXDATA 8
41	struct tpacket_auxdata {
42	uint32_t tp_status;
43	uint32_t tp_len;
44	uint32_t tp_snaplen;
45	uint16_t tp_mac;
46	uint16_t tp_net;
47	uint16_t tp_vlan_tci;
48	uint16_t tp_padding;
49	};
50	#endif
51
52
53	/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
54
55
56	#if ENABLE_LONG_OPTS
57	static const char udhcpc_longopts[] ALIGN1 =
58	"clientid-none\0" No_argument "C"
59	"vendorclass\0" Required_argument "V"
60	"hostname\0" Required_argument "H"
61	"fqdn\0" Required_argument "F"
62	"interface\0" Required_argument "i"
63	"now\0" No_argument "n"
64	"pidfile\0" Required_argument "p"
65	"quit\0" No_argument "q"
66	"release\0" No_argument "R"
67	"request\0" Required_argument "r"
68	"script\0" Required_argument "s"
69	"timeout\0" Required_argument "T"
70	"retries\0" Required_argument "t"
71	"tryagain\0" Required_argument "A"
72	"syslog\0" No_argument "S"
73	"request-option\0" Required_argument "O"
74	"no-default-options\0" No_argument "o"
75	"foreground\0" No_argument "f"
76	"background\0" No_argument "b"
77	"broadcast\0" No_argument "B"
78	IF_FEATURE_UDHCPC_ARPING("arping\0" Optional_argument "a")
79	IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
80	;
81	#endif
82	/* Must match getopt32 option string order */
83	enum {
84	OPT_C = 1 << 0,
85	OPT_V = 1 << 1,
86	OPT_H = 1 << 2,
87	OPT_h = 1 << 3,
88	OPT_F = 1 << 4,
89	OPT_i = 1 << 5,
90	OPT_n = 1 << 6,
91	OPT_p = 1 << 7,
92	OPT_q = 1 << 8,
93	OPT_R = 1 << 9,
94	OPT_r = 1 << 10,
95	OPT_s = 1 << 11,
96	OPT_T = 1 << 12,
97	OPT_t = 1 << 13,
98	OPT_S = 1 << 14,
99	OPT_A = 1 << 15,
100	OPT_O = 1 << 16,
101	OPT_o = 1 << 17,
102	OPT_x = 1 << 18,
103	OPT_f = 1 << 19,
104	OPT_B = 1 << 20,
105	/* The rest has variable bit positions, need to be clever */
106	OPTBIT_B = 20,
107	USE_FOR_MMU( OPTBIT_b,)
108	IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
109	IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
110	USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
111	IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
112	IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
113	};
114
115
116	/*** Script execution code ***/
117
118	/* get a rough idea of how long an option will be (rounding up...) */
119	static const uint8_t len_of_option_as_string[] ALIGN1 = {
120	[OPTION_IP ] = sizeof("255.255.255.255 "),
121	[OPTION_IP_PAIR ] = sizeof("255.255.255.255 ") * 2,
122	[OPTION_STATIC_ROUTES ] = sizeof("255.255.255.255/32 255.255.255.255 "),
123	[OPTION_6RD ] = sizeof("132 128 ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff 255.255.255.255 "),
124	[OPTION_STRING ] = 1,
125	[OPTION_STRING_HOST ] = 1,
126	#if ENABLE_FEATURE_UDHCP_RFC3397
127	[OPTION_DNS_STRING ] = 1, /* unused */
128	/* Hmmm, this severely overestimates size if SIP_SERVERS option
129	* is in domain name form: N-byte option in binary form
130	* mallocs ~16*N bytes. But it is freed almost at once.
131	*/
132	[OPTION_SIP_SERVERS ] = sizeof("255.255.255.255 "),
133	#endif
134	// [OPTION_BOOLEAN ] = sizeof("yes "),
135	[OPTION_U8 ] = sizeof("255 "),
136	[OPTION_U16 ] = sizeof("65535 "),
137	// [OPTION_S16 ] = sizeof("-32768 "),
138	[OPTION_U32 ] = sizeof("4294967295 "),
139	[OPTION_S32 ] = sizeof("-2147483684 "),
140	};
141
142	/* note: ip is a pointer to an IP in network order, possibly misaliged */
143	static int sprint_nip(char *dest, const char *pre, const uint8_t *ip)
144	{
145	return sprintf(dest, "%s%u.%u.%u.%u", pre, ip[0], ip[1], ip[2], ip[3]);
146	}
147
148	/* really simple implementation, just count the bits */
149	static int mton(uint32_t mask)
150	{
151	int i = 0;
152	mask = ntohl(mask); /* 111110000-like bit pattern */
153	while (mask) {
154	i++;
155	mask <<= 1;
156	}
157	return i;
158	}
159
160	#if ENABLE_FEATURE_UDHCPC_SANITIZEOPT
161	/* Check if a given label represents a valid DNS label
162	* Return pointer to the first character after the label upon success,
163	* NULL otherwise.
164	* See RFC1035, 2.3.1
165	*/
166	/* We don't need to be particularly anal. For example, allowing _, hyphen
167	* at the end, or leading and trailing dots would be ok, since it
168	* can't be used for attacks. (Leading hyphen can be, if someone uses
169	* cmd "$hostname"
170	* in the script: then hostname may be treated as an option)
171	*/
172	static const char *valid_domain_label(const char *label)
173	{
174	unsigned char ch;
175	unsigned pos = 0;
176
177	for (;;) {
178	ch = *label;
179	if ((ch|0x20) < 'a' || (ch|0x20) > 'z') {
180	if (ch < '0' || ch > '9') {
181	if (ch == '\0' || ch == '.')
182	return label;
183	/* DNS allows only '-', but we are more permissive */
184	if (ch != '-' && ch != '_')
185	return NULL;
186	}
187	}
188	label++;
189	pos++;
190	//Do we want this?
191	//if (pos > 63) /* NS_MAXLABEL; labels must be 63 chars or less */
192	// return NULL;
193	}
194	}
195
196	/* Check if a given name represents a valid DNS name */
197	/* See RFC1035, 2.3.1 */
198	static int good_hostname(const char *name)
199	{
200	//const char *start = name;
201
202	for (;;) {
203	name = valid_domain_label(name);
204	if (!name)
205	return 0;
206	if (!name[0])
207	return 1;
208	//Do we want this?
209	//return ((name - start) < 1025); /* NS_MAXDNAME */
210	name++;
211	if (*name == '\0')
212	return 1; // We allow trailing dot too
213	}
214	}
215	#else
216	# define good_hostname(name) 1
217	#endif
218
219	/* Create "opt_name=opt_value" string */
220	static NOINLINE char *xmalloc_optname_optval(uint8_t *option, const struct dhcp_optflag *optflag, const char *opt_name)
221	{
222	unsigned upper_length;
223	int len, type, optlen;
224	char *dest, *ret;
225
226	/* option points to OPT_DATA, need to go back to get OPT_LEN */
227	len = option[-OPT_DATA + OPT_LEN];
228
229	type = optflag->flags & OPTION_TYPE_MASK;
230	optlen = dhcp_option_lengths[type];
231	upper_length = len_of_option_as_string[type]
232	* ((unsigned)(len + optlen) / (unsigned)optlen);
233
234	dest = ret = xmalloc(upper_length + strlen(opt_name) + 2);
235	dest += sprintf(ret, "%s=", opt_name);
236
237	while (len >= optlen) {
238	switch (type) {
239	case OPTION_IP:
240	case OPTION_IP_PAIR:
241	dest += sprint_nip(dest, "", option);
242	if (type == OPTION_IP)
243	break;
244	dest += sprint_nip(dest, "/", option + 4);
245	break;
246	// case OPTION_BOOLEAN:
247	// dest += sprintf(dest, *option ? "yes" : "no");
248	// break;
249	case OPTION_U8:
250	dest += sprintf(dest, "%u", *option);
251	break;
252	// case OPTION_S16:
253	case OPTION_U16: {
254	uint16_t val_u16;
255	move_from_unaligned16(val_u16, option);
256	dest += sprintf(dest, "%u", ntohs(val_u16));
257	break;
258	}
259	case OPTION_S32:
260	case OPTION_U32: {
261	uint32_t val_u32;
262	move_from_unaligned32(val_u32, option);
263	dest += sprintf(dest, type == OPTION_U32 ? "%lu" : "%ld", (unsigned long) ntohl(val_u32));
264	break;
265	}
266	/* Note: options which use 'return' instead of 'break'
267	* (for example, OPTION_STRING) skip the code which handles
268	* the case of list of options.
269	*/
270	case OPTION_STRING:
271	case OPTION_STRING_HOST:
272	memcpy(dest, option, len);
273	dest[len] = '\0';
274	if (type == OPTION_STRING_HOST && !good_hostname(dest))
275	safe_strncpy(dest, "bad", len);
276	return ret;
277	case OPTION_STATIC_ROUTES: {
278	/* Option binary format:
279	* mask [one byte, 0..32]
280	* ip [big endian, 0..4 bytes depending on mask]
281	* router [big endian, 4 bytes]
282	* may be repeated
283	*
284	* We convert it to a string "IP/MASK ROUTER IP2/MASK2 ROUTER2"
285	*/
286	const char *pfx = "";
287
288	while (len >= 1 + 4) { /* mask + 0-byte ip + router */
289	uint32_t nip;
290	uint8_t *p;
291	unsigned mask;
292	int bytes;
293
294	mask = *option++;
295	if (mask > 32)
296	break;
297	len--;
298
299	nip = 0;
300	p = (void*) &nip;
301	bytes = (mask + 7) / 8; /* 0 -> 0, 1..8 -> 1, 9..16 -> 2 etc */
302	while (--bytes >= 0) {
303	*p++ = *option++;
304	len--;
305	}
306	if (len < 4)
307	break;
308
309	/* print ip/mask */
310	dest += sprint_nip(dest, pfx, (void*) &nip);
311	pfx = " ";
312	dest += sprintf(dest, "/%u ", mask);
313	/* print router */
314	dest += sprint_nip(dest, "", option);
315	option += 4;
316	len -= 4;
317	}
318
319	return ret;
320	}
321	case OPTION_6RD:
322	/* Option binary format (see RFC 5969):
323	* 0 1 2 3
324	* 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
325	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
326	* | OPTION_6RD | option-length | IPv4MaskLen | 6rdPrefixLen |
327	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
328	* | 6rdPrefix |
329	* ... (16 octets) ...
330	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
331	* ... 6rdBRIPv4Address(es) ...
332	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
333	* We convert it to a string
334	* "IPv4MaskLen 6rdPrefixLen 6rdPrefix 6rdBRIPv4Address..."
335	*
336	* Sanity check: ensure that our length is at least 22 bytes, that
337	* IPv4MaskLen <= 32,
338	* 6rdPrefixLen <= 128,
339	* 6rdPrefixLen + (32 - IPv4MaskLen) <= 128
340	* (2nd condition need no check - it follows from 1st and 3rd).
341	* Else, return envvar with empty value ("optname=")
342	*/
343	if (len >= (1 + 1 + 16 + 4)
344	&& option[0] <= 32
345	&& (option[1] + 32 - option[0]) <= 128
346	) {
347	/* IPv4MaskLen */
348	dest += sprintf(dest, "%u ", *option++);
349	/* 6rdPrefixLen */
350	dest += sprintf(dest, "%u ", *option++);
351	/* 6rdPrefix */
352	dest += sprint_nip6(dest, /* "", */ option);
353	option += 16;
354	len -= 1 + 1 + 16 + 4;
355	/* "+ 4" above corresponds to the length of IPv4 addr
356	* we consume in the loop below */
357	while (1) {
358	/* 6rdBRIPv4Address(es) */
359	dest += sprint_nip(dest, " ", option);
360	option += 4;
361	len -= 4; /* do we have yet another 4+ bytes? */
362	if (len < 0)
363	break; /* no */
364	}
365	}
366
367	return ret;
368	#if ENABLE_FEATURE_UDHCP_RFC3397
369	case OPTION_DNS_STRING:
370	/* unpack option into dest; use ret for prefix (i.e., "optname=") */
371	dest = dname_dec(option, len, ret);
372	if (dest) {
373	free(ret);
374	return dest;
375	}
376	/* error. return "optname=" string */
377	return ret;
378	case OPTION_SIP_SERVERS:
379	/* Option binary format:
380	* type: byte
381	* type=0: domain names, dns-compressed
382	* type=1: IP addrs
383	*/
384	option++;
385	len--;
386	if (option[-1] == 0) {
387	dest = dname_dec(option, len, ret);
388	if (dest) {
389	free(ret);
390	return dest;
391	}
392	} else
393	if (option[-1] == 1) {
394	const char *pfx = "";
395	while (1) {
396	len -= 4;
397	if (len < 0)
398	break;
399	dest += sprint_nip(dest, pfx, option);
400	pfx = " ";
401	option += 4;
402	}
403	}
404	return ret;
405	#endif
406	} /* switch */
407
408	/* If we are here, try to format any remaining data
409	* in the option as another, similarly-formatted option
410	*/
411	option += optlen;
412	len -= optlen;
413	// TODO: it can be a list only if (optflag->flags & OPTION_LIST).
414	// Should we bail out/warn if we see multi-ip option which is
415	// not allowed to be such (for example, DHCP_BROADCAST)? -
416	if (len < optlen /* || !(optflag->flags & OPTION_LIST) */)
417	break;
418	*dest++ = ' ';
419	*dest = '\0';
420	} /* while */
421
422	return ret;
423	}
424
425	/* put all the parameters into the environment */
426	static char **fill_envp(struct dhcp_packet *packet)
427	{
428	int envc;
429	int i;
430	char **envp, **curr;
431	const char *opt_name;
432	uint8_t *temp;
433	uint8_t overload = 0;
434
435	#define BITMAP unsigned
436	#define BBITS (sizeof(BITMAP) * 8)
437	#define BMASK(i) (1 << (i & (sizeof(BITMAP) * 8 - 1)))
438	#define FOUND_OPTS(i) (found_opts[(unsigned)i / BBITS])
439	BITMAP found_opts[256 / BBITS];
440
441	memset(found_opts, 0, sizeof(found_opts));
442
443	/* We need 6 elements for:
444	* "interface=IFACE"
445	* "ip=N.N.N.N" from packet->yiaddr
446	* "siaddr=IP" from packet->siaddr_nip (unless 0)
447	* "boot_file=FILE" from packet->file (unless overloaded)
448	* "sname=SERVER_HOSTNAME" from packet->sname (unless overloaded)
449	* terminating NULL
450	*/
451	envc = 6;
452	/* +1 element for each option, +2 for subnet option: */
453	if (packet) {
454	/* note: do not search for "pad" (0) and "end" (255) options */
455	//TODO: change logic to scan packet _once_
456	for (i = 1; i < 255; i++) {
457	temp = udhcp_get_option(packet, i);
458	if (temp) {
459	if (i == DHCP_OPTION_OVERLOAD)
460	overload |= *temp;
461	else if (i == DHCP_SUBNET)
462	envc++; /* for $mask */
463	envc++;
464	/*if (i != DHCP_MESSAGE_TYPE)*/
465	FOUND_OPTS(i) |= BMASK(i);
466	}
467	}
468	}
469	curr = envp = xzalloc(sizeof(envp[0]) * envc);
470
471	*curr = xasprintf("interface=%s", client_config.interface);
472	putenv(*curr++);
473
474	if (!packet)
475	return envp;
476
477	/* Export BOOTP fields. Fields we don't (yet?) export:
478	* uint8_t op; // always BOOTREPLY
479	* uint8_t htype; // hardware address type. 1 = 10mb ethernet
480	* uint8_t hlen; // hardware address length
481	* uint8_t hops; // used by relay agents only
482	* uint32_t xid;
483	* uint16_t secs; // elapsed since client began acquisition/renewal
484	* uint16_t flags; // only one flag so far: bcast. Never set by server
485	* uint32_t ciaddr; // client IP (usually == yiaddr. can it be different
486	* // if during renew server wants to give us different IP?)
487	* uint32_t gateway_nip; // relay agent IP address
488	* uint8_t chaddr[16]; // link-layer client hardware address (MAC)
489	* TODO: export gateway_nip as $giaddr?
490	*/
491	/* Most important one: yiaddr as $ip */
492	*curr = xmalloc(sizeof("ip=255.255.255.255"));
493	sprint_nip(*curr, "ip=", (uint8_t *) &packet->yiaddr);
494	putenv(*curr++);
495	if (packet->siaddr_nip) {
496	/* IP address of next server to use in bootstrap */
497	*curr = xmalloc(sizeof("siaddr=255.255.255.255"));
498	sprint_nip(*curr, "siaddr=", (uint8_t *) &packet->siaddr_nip);
499	putenv(*curr++);
500	}
501	if (!(overload & FILE_FIELD) && packet->file[0]) {
502	/* watch out for invalid packets */
503	*curr = xasprintf("boot_file=%."DHCP_PKT_FILE_LEN_STR"s", packet->file);
504	putenv(*curr++);
505	}
506	if (!(overload & SNAME_FIELD) && packet->sname[0]) {
507	/* watch out for invalid packets */
508	*curr = xasprintf("sname=%."DHCP_PKT_SNAME_LEN_STR"s", packet->sname);
509	putenv(*curr++);
510	}
511
512	/* Export known DHCP options */
513	opt_name = dhcp_option_strings;
514	i = 0;
515	while (*opt_name) {
516	uint8_t code = dhcp_optflags[i].code;
517	BITMAP *found_ptr = &FOUND_OPTS(code);
518	BITMAP found_mask = BMASK(code);
519	if (!(*found_ptr & found_mask))
520	goto next;
521	*found_ptr &= ~found_mask; /* leave only unknown options */
522	temp = udhcp_get_option(packet, code);
523	*curr = xmalloc_optname_optval(temp, &dhcp_optflags[i], opt_name);
524	putenv(*curr++);
525	if (code == DHCP_SUBNET) {
526	/* Subnet option: make things like "$ip/$mask" possible */
527	uint32_t subnet;
528	move_from_unaligned32(subnet, temp);
529	*curr = xasprintf("mask=%u", mton(subnet));
530	putenv(*curr++);
531	}
532	next:
533	opt_name += strlen(opt_name) + 1;
534	i++;
535	}
536	/* Export unknown options */
537	for (i = 0; i < 256;) {
538	BITMAP bitmap = FOUND_OPTS(i);
539	if (!bitmap) {
540	i += BBITS;
541	continue;
542	}
543	if (bitmap & BMASK(i)) {
544	unsigned len, ofs;
545
546	temp = udhcp_get_option(packet, i);
547	/* udhcp_get_option returns ptr to data portion,
548	* need to go back to get len
549	*/
550	len = temp[-OPT_DATA + OPT_LEN];
551	*curr = xmalloc(sizeof("optNNN=") + 1 + len*2);
552	ofs = sprintf(*curr, "opt%u=", i);
553	*bin2hex(*curr + ofs, (void*) temp, len) = '\0';
554	putenv(*curr++);
555	}
556	i++;
557	}
558
559	return envp;
560	}
561
562	/* Call a script with a par file and env vars */
563	static void udhcp_run_script(struct dhcp_packet *packet, const char *name)
564	{
565	char **envp, **curr;
566	char *argv[3];
567
568	envp = fill_envp(packet);
569
570	/* call script */
571	log1("executing %s %s", client_config.script, name);
572	argv[0] = (char*) client_config.script;
573	argv[1] = (char*) name;
574	argv[2] = NULL;
575	spawn_and_wait(argv);
576
577	for (curr = envp; *curr; curr++) {
578	log2(" %s", *curr);
579	bb_unsetenv_and_free(*curr);
580	}
581	free(envp);
582	}
583
584
585	/*** Sending/receiving packets ***/
586
587	static ALWAYS_INLINE uint32_t random_xid(void)
588	{
589	return rand();
590	}
591
592	/* Initialize the packet with the proper defaults */
593	static void init_packet(struct dhcp_packet *packet, char type)
594	{
595	uint16_t secs;
596
597	/* Fill in: op, htype, hlen, cookie fields; message type option: */
598	udhcp_init_header(packet, type);
599
600	packet->xid = random_xid();
601
602	client_config.last_secs = monotonic_sec();
603	if (client_config.first_secs == 0)
604	client_config.first_secs = client_config.last_secs;
605	secs = client_config.last_secs - client_config.first_secs;
606	packet->secs = htons(secs);
607
608	memcpy(packet->chaddr, client_config.client_mac, 6);
609	if (client_config.clientid)
610	udhcp_add_binary_option(packet, client_config.clientid);
611	}
612
613	static void add_client_options(struct dhcp_packet *packet)
614	{
615	int i, end, len;
616
617	udhcp_add_simple_option(packet, DHCP_MAX_SIZE, htons(IP_UDP_DHCP_SIZE));
618
619	/* Add a "param req" option with the list of options we'd like to have
620	* from stubborn DHCP servers. Pull the data from the struct in common.c.
621	* No bounds checking because it goes towards the head of the packet. */
622	end = udhcp_end_option(packet->options);
623	len = 0;
624	for (i = 1; i < DHCP_END; i++) {
625	if (client_config.opt_mask[i >> 3] & (1 << (i & 7))) {
626	packet->options[end + OPT_DATA + len] = i;
627	len++;
628	}
629	}
630	if (len) {
631	packet->options[end + OPT_CODE] = DHCP_PARAM_REQ;
632	packet->options[end + OPT_LEN] = len;
633	packet->options[end + OPT_DATA + len] = DHCP_END;
634	}
635
636	if (client_config.vendorclass)
637	udhcp_add_binary_option(packet, client_config.vendorclass);
638	if (client_config.hostname)
639	udhcp_add_binary_option(packet, client_config.hostname);
640	if (client_config.fqdn)
641	udhcp_add_binary_option(packet, client_config.fqdn);
642
643	/* Request broadcast replies if we have no IP addr */
644	if ((option_mask32 & OPT_B) && packet->ciaddr == 0)
645	packet->flags |= htons(BROADCAST_FLAG);
646
647	/* Add -x options if any */
648	{
649	struct option_set *curr = client_config.options;
650	while (curr) {
651	udhcp_add_binary_option(packet, curr->data);
652	curr = curr->next;
653	}
654	// if (client_config.sname)
655	// strncpy((char*)packet->sname, client_config.sname, sizeof(packet->sname) - 1);
656	// if (client_config.boot_file)
657	// strncpy((char*)packet->file, client_config.boot_file, sizeof(packet->file) - 1);
658	}
659
660	// This will be needed if we remove -V VENDOR_STR in favor of
661	// -x vendor:VENDOR_STR
662	//if (!udhcp_find_option(packet.options, DHCP_VENDOR))
663	// /* not set, set the default vendor ID */
664	// ...add (DHCP_VENDOR, "udhcp "BB_VER) opt...
665	}
666
667	/* RFC 2131
668	* 4.4.4 Use of broadcast and unicast
669	*
670	* The DHCP client broadcasts DHCPDISCOVER, DHCPREQUEST and DHCPINFORM
671	* messages, unless the client knows the address of a DHCP server.
672	* The client unicasts DHCPRELEASE messages to the server. Because
673	* the client is declining the use of the IP address supplied by the server,
674	* the client broadcasts DHCPDECLINE messages.
675	*
676	* When the DHCP client knows the address of a DHCP server, in either
677	* INIT or REBOOTING state, the client may use that address
678	* in the DHCPDISCOVER or DHCPREQUEST rather than the IP broadcast address.
679	* The client may also use unicast to send DHCPINFORM messages
680	* to a known DHCP server. If the client receives no response to DHCP
681	* messages sent to the IP address of a known DHCP server, the DHCP
682	* client reverts to using the IP broadcast address.
683	*/
684
685	static int raw_bcast_from_client_config_ifindex(struct dhcp_packet *packet, uint32_t src_nip)
686	{
687	return udhcp_send_raw_packet(packet,
688	/*src*/ src_nip, CLIENT_PORT,
689	/*dst*/ INADDR_BROADCAST, SERVER_PORT, MAC_BCAST_ADDR,
690	client_config.ifindex);
691	}
692
693	static int bcast_or_ucast(struct dhcp_packet *packet, uint32_t ciaddr, uint32_t server)
694	{
695	if (server)
696	return udhcp_send_kernel_packet(packet,
697	ciaddr, CLIENT_PORT,
698	server, SERVER_PORT);
699	return raw_bcast_from_client_config_ifindex(packet, ciaddr);
700	}
701
702	/* Broadcast a DHCP discover packet to the network, with an optionally requested IP */
703	/* NOINLINE: limit stack usage in caller */
704	static NOINLINE int send_discover(uint32_t xid, uint32_t requested)
705	{
706	struct dhcp_packet packet;
707
708	/* Fill in: op, htype, hlen, cookie, chaddr fields,
709	* random xid field (we override it below),
710	* client-id option (unless -C), message type option:
711	*/
712	init_packet(&packet, DHCPDISCOVER);
713
714	packet.xid = xid;
715	if (requested)
716	udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
717
718	/* Add options: maxsize,
719	* optionally: hostname, fqdn, vendorclass,
720	* "param req" option according to -O, options specified with -x
721	*/
722	add_client_options(&packet);
723
724	bb_error_msg("sending %s", "discover");
725	return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
726	}
727
728	/* Broadcast a DHCP request message */
729	/* RFC 2131 3.1 paragraph 3:
730	* "The client _broadcasts_ a DHCPREQUEST message..."
731	*/
732	/* NOINLINE: limit stack usage in caller */
733	static NOINLINE int send_select(uint32_t xid, uint32_t server, uint32_t requested)
734	{
735	struct dhcp_packet packet;
736	struct in_addr addr;
737
738	/*
739	* RFC 2131 4.3.2 DHCPREQUEST message
740	* ...
741	* If the DHCPREQUEST message contains a 'server identifier'
742	* option, the message is in response to a DHCPOFFER message.
743	* Otherwise, the message is a request to verify or extend an
744	* existing lease. If the client uses a 'client identifier'
745	* in a DHCPREQUEST message, it MUST use that same 'client identifier'
746	* in all subsequent messages. If the client included a list
747	* of requested parameters in a DHCPDISCOVER message, it MUST
748	* include that list in all subsequent messages.
749	*/
750	/* Fill in: op, htype, hlen, cookie, chaddr fields,
751	* random xid field (we override it below),
752	* client-id option (unless -C), message type option:
753	*/
754	init_packet(&packet, DHCPREQUEST);
755
756	packet.xid = xid;
757	udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
758
759	udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
760
761	/* Add options: maxsize,
762	* optionally: hostname, fqdn, vendorclass,
763	* "param req" option according to -O, and options specified with -x
764	*/
765	add_client_options(&packet);
766
767	addr.s_addr = requested;
768	bb_error_msg("sending select for %s", inet_ntoa(addr));
769	return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
770	}
771
772	/* Unicast or broadcast a DHCP renew message */
773	/* NOINLINE: limit stack usage in caller */
774	static NOINLINE int send_renew(uint32_t xid, uint32_t server, uint32_t ciaddr)
775	{
776	struct dhcp_packet packet;
777
778	/*
779	* RFC 2131 4.3.2 DHCPREQUEST message
780	* ...
781	* DHCPREQUEST generated during RENEWING state:
782	*
783	* 'server identifier' MUST NOT be filled in, 'requested IP address'
784	* option MUST NOT be filled in, 'ciaddr' MUST be filled in with
785	* client's IP address. In this situation, the client is completely
786	* configured, and is trying to extend its lease. This message will
787	* be unicast, so no relay agents will be involved in its
788	* transmission. Because 'giaddr' is therefore not filled in, the
789	* DHCP server will trust the value in 'ciaddr', and use it when
790	* replying to the client.
791	*/
792	/* Fill in: op, htype, hlen, cookie, chaddr fields,
793	* random xid field (we override it below),
794	* client-id option (unless -C), message type option:
795	*/
796	init_packet(&packet, DHCPREQUEST);
797
798	packet.xid = xid;
799	packet.ciaddr = ciaddr;
800
801	/* Add options: maxsize,
802	* optionally: hostname, fqdn, vendorclass,
803	* "param req" option according to -O, and options specified with -x
804	*/
805	add_client_options(&packet);
806
807	bb_error_msg("sending %s", "renew");
808	return bcast_or_ucast(&packet, ciaddr, server);
809	}
810
811	#if ENABLE_FEATURE_UDHCPC_ARPING
812	/* Broadcast a DHCP decline message */
813	/* NOINLINE: limit stack usage in caller */
814	static NOINLINE int send_decline(/*uint32_t xid,*/ uint32_t server, uint32_t requested)
815	{
816	struct dhcp_packet packet;
817
818	/* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
819	* client-id option (unless -C), message type option:
820	*/
821	init_packet(&packet, DHCPDECLINE);
822
823	#if 0
824	/* RFC 2131 says DHCPDECLINE's xid is randomly selected by client,
825	* but in case the server is buggy and wants DHCPDECLINE's xid
826	* to match the xid which started entire handshake,
827	* we use the same xid we used in initial DHCPDISCOVER:
828	*/
829	packet.xid = xid;
830	#endif
831	/* DHCPDECLINE uses "requested ip", not ciaddr, to store offered IP */
832	udhcp_add_simple_option(&packet, DHCP_REQUESTED_IP, requested);
833
834	udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
835
836	bb_error_msg("sending %s", "decline");
837	return raw_bcast_from_client_config_ifindex(&packet, INADDR_ANY);
838	}
839	#endif
840
841	/* Unicast a DHCP release message */
842	static int send_release(uint32_t server, uint32_t ciaddr)
843	{
844	struct dhcp_packet packet;
845
846	/* Fill in: op, htype, hlen, cookie, chaddr, random xid fields,
847	* client-id option (unless -C), message type option:
848	*/
849	init_packet(&packet, DHCPRELEASE);
850
851	/* DHCPRELEASE uses ciaddr, not "requested ip", to store IP being released */
852	packet.ciaddr = ciaddr;
853
854	udhcp_add_simple_option(&packet, DHCP_SERVER_ID, server);
855
856	bb_error_msg("sending %s", "release");
857	/* Note: normally we unicast here since "server" is not zero.
858	* However, there _are_ people who run "address-less" DHCP servers,
859	* and reportedly ISC dhcp client and Windows allow that.
860	*/
861	return bcast_or_ucast(&packet, ciaddr, server);
862	}
863
864	/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
865	/* NOINLINE: limit stack usage in caller */
866	static NOINLINE int udhcp_recv_raw_packet(struct dhcp_packet *dhcp_pkt, int fd)
867	{
868	int bytes;
869	struct ip_udp_dhcp_packet packet;
870	uint16_t check;
871	unsigned char cmsgbuf[CMSG_LEN(sizeof(struct tpacket_auxdata))];
872	struct iovec iov;
873	struct msghdr msg;
874	struct cmsghdr *cmsg;
875
876	/* used to use just safe_read(fd, &packet, sizeof(packet))
877	* but we need to check for TP_STATUS_CSUMNOTREADY :(
878	*/
879	iov.iov_base = &packet;
880	iov.iov_len = sizeof(packet);
881	memset(&msg, 0, sizeof(msg));
882	msg.msg_iov = &iov;
883	msg.msg_iovlen = 1;
884	msg.msg_control = cmsgbuf;
885	msg.msg_controllen = sizeof(cmsgbuf);
886	for (;;) {
887	bytes = recvmsg(fd, &msg, 0);
888	if (bytes < 0) {
889	if (errno == EINTR)
890	continue;
891	log1("packet read error, ignoring");
892	/* NB: possible down interface, etc. Caller should pause. */
893	return bytes; /* returns -1 */
894	}
895	break;
896	}
897
898	if (bytes < (int) (sizeof(packet.ip) + sizeof(packet.udp))) {
899	log1("packet is too short, ignoring");
900	return -2;
901	}
902
903	if (bytes < ntohs(packet.ip.tot_len)) {
904	/* packet is bigger than sizeof(packet), we did partial read */
905	log1("oversized packet, ignoring");
906	return -2;
907	}
908
909	/* ignore any extra garbage bytes */
910	bytes = ntohs(packet.ip.tot_len);
911
912	/* make sure its the right packet for us, and that it passes sanity checks */
913	if (packet.ip.protocol != IPPROTO_UDP
914	|| packet.ip.version != IPVERSION
915	|| packet.ip.ihl != (sizeof(packet.ip) >> 2)
916	|| packet.udp.dest != htons(CLIENT_PORT)
917	/* || bytes > (int) sizeof(packet) - can't happen */
918	|| ntohs(packet.udp.len) != (uint16_t)(bytes - sizeof(packet.ip))
919	) {
920	log1("unrelated/bogus packet, ignoring");
921	return -2;
922	}
923
924	/* verify IP checksum */
925	check = packet.ip.check;
926	packet.ip.check = 0;
927	if (check != inet_cksum((uint16_t *)&packet.ip, sizeof(packet.ip))) {
928	log1("bad IP header checksum, ignoring");
929	return -2;
930	}
931
932	for (cmsg = CMSG_FIRSTHDR(&msg); cmsg; cmsg = CMSG_NXTHDR(&msg, cmsg)) {
933	if (cmsg->cmsg_level == SOL_PACKET
934	&& cmsg->cmsg_type == PACKET_AUXDATA
935	) {
936	/* some VMs don't checksum UDP and TCP data
937	* they send to the same physical machine,
938	* here we detect this case:
939	*/
940	struct tpacket_auxdata *aux = (void *)CMSG_DATA(cmsg);
941	if (aux->tp_status & TP_STATUS_CSUMNOTREADY)
942	goto skip_udp_sum_check;
943	}
944	}
945
946	/* verify UDP checksum. IP header has to be modified for this */
947	memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
948	/* ip.xx fields which are not memset: protocol, check, saddr, daddr */
949	packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
950	check = packet.udp.check;
951	packet.udp.check = 0;
952	if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
953	log1("packet with bad UDP checksum received, ignoring");
954	return -2;
955	}
956	skip_udp_sum_check:
957
958	if (packet.data.cookie != htonl(DHCP_MAGIC)) {
959	bb_error_msg("packet with bad magic, ignoring");
960	return -2;
961	}
962
963	log1("received %s", "a packet");
964	udhcp_dump_packet(&packet.data);
965
966	bytes -= sizeof(packet.ip) + sizeof(packet.udp);
967	memcpy(dhcp_pkt, &packet.data, bytes);
968	return bytes;
969	}
970
971
972	/*** Main ***/
973
974	static int sockfd = -1;
975
976	#define LISTEN_NONE 0
977	#define LISTEN_KERNEL 1
978	#define LISTEN_RAW 2
979	static smallint listen_mode;
980
981	/* initial state: (re)start DHCP negotiation */
982	#define INIT_SELECTING 0
983	/* discover was sent, DHCPOFFER reply received */
984	#define REQUESTING 1
985	/* select/renew was sent, DHCPACK reply received */
986	#define BOUND 2
987	/* half of lease passed, want to renew it by sending unicast renew requests */
988	#define RENEWING 3
989	/* renew requests were not answered, lease is almost over, send broadcast renew */
990	#define REBINDING 4
991	/* manually requested renew (SIGUSR1) */
992	#define RENEW_REQUESTED 5
993	/* release, possibly manually requested (SIGUSR2) */
994	#define RELEASED 6
995	static smallint state;
996
997	static int udhcp_raw_socket(int ifindex)
998	{
999	int fd;
1000	struct sockaddr_ll sock;
1001
1002	log1("opening raw socket on ifindex %d", ifindex); //log2?
1003
1004	fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));
1005	/* ^^^^^
1006	* SOCK_DGRAM: remove link-layer headers on input (SOCK_RAW keeps them)
1007	* ETH_P_IP: want to receive only packets with IPv4 eth type
1008	*/
1009	log1("got raw socket fd"); //log2?
1010
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));
1015
1016	#if 0 /* Several users reported breakage when BPF filter is used */
1017	if (CLIENT_PORT == 68) {
1018	/* Use only if standard port is in use */
1019	/*
1020	* I've selected not to see LL header, so BPF doesn't see it, too.
1021	* The filter may also pass non-IP and non-ARP packets, but we do
1022	* a more complete check when receiving the message in userspace.
1023	*
1024	* and filter shamelessly stolen from:
1025	*
1026	* http://www.flamewarmaster.de/software/dhcpclient/
1027	*
1028	* There are a few other interesting ideas on that page (look under
1029	* "Motivation"). Use of netlink events is most interesting. Think
1030	* of various network servers listening for events and reconfiguring.
1031	* That would obsolete sending HUP signals and/or make use of restarts.
1032	*
1033	* Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
1034	* License: GPL v2.
1035	*/
1036	static const struct sock_filter filter_instr[] = {
1037	/* load 9th byte (protocol) */
1038	BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
1039	/* jump to L1 if it is IPPROTO_UDP, else to L4 */
1040	BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
1041	/* L1: load halfword from offset 6 (flags and frag offset) */
1042	BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
1043	/* jump to L4 if any bits in frag offset field are set, else to L2 */
1044	BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
1045	/* L2: skip IP header (load index reg with header len) */
1046	BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
1047	/* load udp destination port from halfword[header_len + 2] */
1048	BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
1049	/* jump to L3 if udp dport is CLIENT_PORT, else to L4 */
1050	BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
1051	/* L3: accept packet ("accept 0x7fffffff bytes") */
1052	/* Accepting 0xffffffff works too but kernel 2.6.19 is buggy */
1053	BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
1054	/* L4: discard packet ("accept zero bytes") */
1055	BPF_STMT(BPF_RET|BPF_K, 0),
1056	};
1057	static const struct sock_fprog filter_prog = {
1058	.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
1059	/* casting const away: */
1060	.filter = (struct sock_filter *) filter_instr,
1061	};
1062	/* Ignoring error (kernel may lack support for this) */
1063	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
1064	sizeof(filter_prog)) >= 0)
1065	log1("attached filter to raw socket fd"); // log?
1066	}
1067	#endif
1068
1069	if (setsockopt_1(fd, SOL_PACKET, PACKET_AUXDATA) != 0) {
1070	if (errno != ENOPROTOOPT)
1071	log1("can't set PACKET_AUXDATA on raw socket");
1072	}
1073
1074	log1("created raw socket");
1075
1076	return fd;
1077	}
1078
1079	static void change_listen_mode(int new_mode)
1080	{
1081	log1("entering listen mode: %s",
1082	new_mode != LISTEN_NONE
1083	? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
1084	: "none"
1085	);
1086
1087	listen_mode = new_mode;
1088	if (sockfd >= 0) {
1089	close(sockfd);
1090	sockfd = -1;
1091	}
1092	if (new_mode == LISTEN_KERNEL)
1093	sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT, client_config.interface);
1094	else if (new_mode != LISTEN_NONE)
1095	sockfd = udhcp_raw_socket(client_config.ifindex);
1096	/* else LISTEN_NONE: sockfd stays closed */
1097	}
1098
1099	/* Called only on SIGUSR1 */
1100	static void perform_renew(void)
1101	{
1102	bb_error_msg("performing DHCP renew");
1103	switch (state) {
1104	case BOUND:
1105	change_listen_mode(LISTEN_KERNEL);
1106	case RENEWING:
1107	case REBINDING:
1108	state = RENEW_REQUESTED;
1109	break;
1110	case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
1111	udhcp_run_script(NULL, "deconfig");
1112	case REQUESTING:
1113	case RELEASED:
1114	change_listen_mode(LISTEN_RAW);
1115	state = INIT_SELECTING;
1116	break;
1117	case INIT_SELECTING:
1118	break;
1119	}
1120	}
1121
1122	static void perform_release(uint32_t server_addr, uint32_t requested_ip)
1123	{
1124	char buffer[sizeof("255.255.255.255")];
1125	struct in_addr temp_addr;
1126
1127	/* send release packet */
1128	if (state == BOUND
1129	|| state == RENEWING
1130	|| state == REBINDING
1131	|| state == RENEW_REQUESTED
1132	) {
1133	temp_addr.s_addr = server_addr;
1134	strcpy(buffer, inet_ntoa(temp_addr));
1135	temp_addr.s_addr = requested_ip;
1136	bb_error_msg("unicasting a release of %s to %s",
1137	inet_ntoa(temp_addr), buffer);
1138	send_release(server_addr, requested_ip); /* unicast */
1139	}
1140	bb_error_msg("entering released state");
1141	/*
1142	* We can be here on: SIGUSR2,
1143	* or on exit (SIGTERM) and -R "release on quit" is specified.
1144	* Users requested to be notified in all cases, even if not in one
1145	* of the states above.
1146	*/
1147	udhcp_run_script(NULL, "deconfig");
1148
1149	change_listen_mode(LISTEN_NONE);
1150	state = RELEASED;
1151	}
1152
1153	static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
1154	{
1155	uint8_t *storage;
1156	int len = strnlen(str, 255);
1157	storage = xzalloc(len + extra + OPT_DATA);
1158	storage[OPT_CODE] = code;
1159	storage[OPT_LEN] = len + extra;
1160	memcpy(storage + extra + OPT_DATA, str, len);
1161	return storage;
1162	}
1163
1164	#if BB_MMU
1165	static void client_background(void)
1166	{
1167	bb_daemonize(0);
1168	logmode &= ~LOGMODE_STDIO;
1169	/* rewrite pidfile, as our pid is different now */
1170	write_pidfile(client_config.pidfile);
1171	}
1172	#endif
1173
1174	//usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
1175	//usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
1176	//usage:#else
1177	//usage:# define IF_UDHCP_VERBOSE(...)
1178	//usage:#endif
1179	//usage:#define udhcpc_trivial_usage
1180	//usage: "[-fbq"IF_UDHCP_VERBOSE("v")"RB]"IF_FEATURE_UDHCPC_ARPING(" [-a[MSEC]]")" [-t N] [-T SEC] [-A SEC/-n]\n"
1181	//usage: " [-i IFACE]"IF_FEATURE_UDHCP_PORT(" [-P PORT]")" [-s PROG] [-p PIDFILE]\n"
1182	//usage: " [-oC] [-r IP] [-V VENDOR] [-F NAME] [-x OPT:VAL]... [-O OPT]..."
1183	//usage:#define udhcpc_full_usage "\n"
1184	//usage: IF_LONG_OPTS(
1185	//usage: "\n -i,--interface IFACE Interface to use (default eth0)"
1186	//usage: IF_FEATURE_UDHCP_PORT(
1187	//usage: "\n -P,--client-port PORT Use PORT (default 68)"
1188	//usage: )
1189	//usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1190	//usage: "\n -p,--pidfile FILE Create pidfile"
1191	//usage: "\n -B,--broadcast Request broadcast replies"
1192	//usage: "\n -t,--retries N Send up to N discover packets (default 3)"
1193	//usage: "\n -T,--timeout SEC Pause between packets (default 3)"
1194	//usage: "\n -A,--tryagain SEC Wait if lease is not obtained (default 20)"
1195	//usage: "\n -n,--now Exit if lease is not obtained"
1196	//usage: "\n -q,--quit Exit after obtaining lease"
1197	//usage: "\n -R,--release Release IP on exit"
1198	//usage: "\n -f,--foreground Run in foreground"
1199	//usage: USE_FOR_MMU(
1200	//usage: "\n -b,--background Background if lease is not obtained"
1201	//usage: )
1202	//usage: "\n -S,--syslog Log to syslog too"
1203	//usage: IF_FEATURE_UDHCPC_ARPING(
1204	//usage: "\n -a[MSEC],--arping[=MSEC] Validate offered address with ARP ping"
1205	//usage: )
1206	//usage: "\n -r,--request IP Request this IP address"
1207	//usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
1208	//usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
1209	//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1210	//usage: "\n Examples of string, numeric, and hex byte opts:"
1211	//usage: "\n -x hostname:bbox - option 12"
1212	//usage: "\n -x lease:3600 - option 51 (lease time)"
1213	//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1214	//usage: "\n -F,--fqdn NAME Ask server to update DNS mapping for NAME"
1215	//usage: "\n -V,--vendorclass VENDOR Vendor identifier (default 'udhcp VERSION')"
1216	//usage: "\n -C,--clientid-none Don't send MAC as client identifier"
1217	//usage: IF_UDHCP_VERBOSE(
1218	//usage: "\n -v Verbose"
1219	//usage: )
1220	//usage: )
1221	//usage: IF_NOT_LONG_OPTS(
1222	//usage: "\n -i IFACE Interface to use (default eth0)"
1223	//usage: IF_FEATURE_UDHCP_PORT(
1224	//usage: "\n -P PORT Use PORT (default 68)"
1225	//usage: )
1226	//usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
1227	//usage: "\n -p FILE Create pidfile"
1228	//usage: "\n -B Request broadcast replies"
1229	//usage: "\n -t N Send up to N discover packets (default 3)"
1230	//usage: "\n -T SEC Pause between packets (default 3)"
1231	//usage: "\n -A SEC Wait if lease is not obtained (default 20)"
1232	//usage: "\n -n Exit if lease is not obtained"
1233	//usage: "\n -q Exit after obtaining lease"
1234	//usage: "\n -R Release IP on exit"
1235	//usage: "\n -f Run in foreground"
1236	//usage: USE_FOR_MMU(
1237	//usage: "\n -b Background if lease is not obtained"
1238	//usage: )
1239	//usage: "\n -S Log to syslog too"
1240	//usage: IF_FEATURE_UDHCPC_ARPING(
1241	//usage: "\n -a[MSEC] Validate offered address with ARP ping"
1242	//usage: )
1243	//usage: "\n -r IP Request this IP address"
1244	//usage: "\n -o Don't request any options (unless -O is given)"
1245	//usage: "\n -O OPT Request option OPT from server (cumulative)"
1246	//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
1247	//usage: "\n Examples of string, numeric, and hex byte opts:"
1248	//usage: "\n -x hostname:bbox - option 12"
1249	//usage: "\n -x lease:3600 - option 51 (lease time)"
1250	//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
1251	//usage: "\n -F NAME Ask server to update DNS mapping for NAME"
1252	//usage: "\n -V VENDOR Vendor identifier (default 'udhcp VERSION')"
1253	//usage: "\n -C Don't send MAC as client identifier"
1254	//usage: IF_UDHCP_VERBOSE(
1255	//usage: "\n -v Verbose"
1256	//usage: )
1257	//usage: )
1258	//usage: "\nSignals:"
1259	//usage: "\n USR1 Renew lease"
1260	//usage: "\n USR2 Release lease"
1261
1262
1263	int udhcpc_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
1264	int udhcpc_main(int argc UNUSED_PARAM, char **argv)
1265	{
1266	uint8_t *message;
1267	const char *str_V, *str_h, *str_F, *str_r;
1268	IF_FEATURE_UDHCPC_ARPING(const char *str_a = "2000";)
1269	IF_FEATURE_UDHCP_PORT(char *str_P;)
1270	void *clientid_mac_ptr;
1271	llist_t *list_O = NULL;
1272	llist_t *list_x = NULL;
1273	int tryagain_timeout = 20;
1274	int discover_timeout = 3;
1275	int discover_retries = 3;
1276	uint32_t server_addr = server_addr; /* for compiler */
1277	uint32_t requested_ip = 0;
1278	uint32_t xid = xid; /* for compiler */
1279	int packet_num;
1280	int timeout; /* must be signed */
1281	unsigned already_waited_sec;
1282	unsigned opt;
1283	IF_FEATURE_UDHCPC_ARPING(unsigned arpping_ms;)
1284	int max_fd;
1285	int retval;
1286	fd_set rfds;
1287
1288	setup_common_bufsiz();
1289
1290	/* Default options */
1291	IF_FEATURE_UDHCP_PORT(SERVER_PORT = 67;)
1292	IF_FEATURE_UDHCP_PORT(CLIENT_PORT = 68;)
1293	client_config.interface = "eth0";
1294	client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
1295	str_V = "udhcp "BB_VER;
1296
1297	/* Parse command line */
1298	/* O,x: list; -T,-t,-A take numeric param */
1299	IF_UDHCP_VERBOSE(opt_complementary = "vv";)
1300	IF_LONG_OPTS(applet_long_options = udhcpc_longopts;)
1301	opt = getopt32(argv, "CV:H:h:F:i:np:qRr:s:T:+t:+SA:+O:*ox:*fB"
1302	USE_FOR_MMU("b")
1303	IF_FEATURE_UDHCPC_ARPING("a::")
1304	IF_FEATURE_UDHCP_PORT("P:")
1305	"v"
1306	, &str_V, &str_h, &str_h, &str_F
1307	, &client_config.interface, &client_config.pidfile, &str_r /* i,p */
1308	, &client_config.script /* s */
1309	, &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
1310	, &list_O
1311	, &list_x
1312	IF_FEATURE_UDHCPC_ARPING(, &str_a)
1313	IF_FEATURE_UDHCP_PORT(, &str_P)
1314	IF_UDHCP_VERBOSE(, &dhcp_verbose)
1315	);
1316	if (opt & (OPT_h|OPT_H)) {
1317	//msg added 2011-11
1318	bb_error_msg("option -h NAME is deprecated, use -x hostname:NAME");
1319	client_config.hostname = alloc_dhcp_option(DHCP_HOST_NAME, str_h, 0);
1320	}
1321	if (opt & OPT_F) {
1322	/* FQDN option format: [0x51][len][flags][0][0]<fqdn> */
1323	client_config.fqdn = alloc_dhcp_option(DHCP_FQDN, str_F, 3);
1324	/* Flag bits: 0000NEOS
1325	* S: 1 = Client requests server to update A RR in DNS as well as PTR
1326	* O: 1 = Server indicates to client that DNS has been updated regardless
1327	* E: 1 = Name is in DNS format, i.e. <4>host<6>domain<3>com<0>,
1328	* not "host.domain.com". Format 0 is obsolete.
1329	* N: 1 = Client requests server to not update DNS (S must be 0 then)
1330	* Two [0] bytes which follow are deprecated and must be 0.
1331	*/
1332	client_config.fqdn[OPT_DATA + 0] = 0x1;
1333	/*client_config.fqdn[OPT_DATA + 1] = 0; - xzalloc did it */
1334	/*client_config.fqdn[OPT_DATA + 2] = 0; */
1335	}
1336	if (opt & OPT_r)
1337	requested_ip = inet_addr(str_r);
1338	#if ENABLE_FEATURE_UDHCP_PORT
1339	if (opt & OPT_P) {
1340	CLIENT_PORT = xatou16(str_P);
1341	SERVER_PORT = CLIENT_PORT - 1;
1342	}
1343	#endif
1344	IF_FEATURE_UDHCPC_ARPING(arpping_ms = xatou(str_a);)
1345	while (list_O) {
1346	char *optstr = llist_pop(&list_O);
1347	unsigned n = bb_strtou(optstr, NULL, 0);
1348	if (errno || n > 254) {
1349	n = udhcp_option_idx(optstr);
1350	n = dhcp_optflags[n].code;
1351	}
1352	client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1353	}
1354	if (!(opt & OPT_o)) {
1355	unsigned i, n;
1356	for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
1357	if (dhcp_optflags[i].flags & OPTION_REQ) {
1358	client_config.opt_mask[n >> 3] |= 1 << (n & 7);
1359	}
1360	}
1361	}
1362	while (list_x) {
1363	char *optstr = llist_pop(&list_x);
1364	char *colon = strchr(optstr, ':');
1365	if (colon)
1366	*colon = ' ';
1367	/* now it looks similar to udhcpd's config file line:
1368	* "optname optval", using the common routine: */
1369	udhcp_str2optset(optstr, &client_config.options);
1370	}
1371
1372	if (udhcp_read_interface(client_config.interface,
1373	&client_config.ifindex,
1374	NULL,
1375	client_config.client_mac)
1376	) {
1377	return 1;
1378	}
1379
1380	clientid_mac_ptr = NULL;
1381	if (!(opt & OPT_C) && !udhcp_find_option(client_config.options, DHCP_CLIENT_ID)) {
1382	/* not suppressed and not set, set the default client ID */
1383	client_config.clientid = alloc_dhcp_option(DHCP_CLIENT_ID, "", 7);
1384	client_config.clientid[OPT_DATA] = 1; /* type: ethernet */
1385	clientid_mac_ptr = client_config.clientid + OPT_DATA+1;
1386	memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1387	}
1388	if (str_V[0] != '\0') {
1389	// can drop -V, str_V, client_config.vendorclass,
1390	// but need to add "vendor" to the list of recognized
1391	// string opts for this to work;
1392	// and need to tweak add_client_options() too...
1393	// ...so the question is, should we?
1394	//bb_error_msg("option -V VENDOR is deprecated, use -x vendor:VENDOR");
1395	client_config.vendorclass = alloc_dhcp_option(DHCP_VENDOR, str_V, 0);
1396	}
1397
1398	#if !BB_MMU
1399	/* on NOMMU reexec (i.e., background) early */
1400	if (!(opt & OPT_f)) {
1401	bb_daemonize_or_rexec(0 /* flags */, argv);
1402	logmode = LOGMODE_NONE;
1403	}
1404	#endif
1405	if (opt & OPT_S) {
1406	openlog(applet_name, LOG_PID, LOG_DAEMON);
1407	logmode |= LOGMODE_SYSLOG;
1408	}
1409
1410	/* Make sure fd 0,1,2 are open */
1411	bb_sanitize_stdio();
1412	/* Equivalent of doing a fflush after every \n */
1413	setlinebuf(stdout);
1414	/* Create pidfile */
1415	write_pidfile(client_config.pidfile);
1416	/* Goes to stdout (unless NOMMU) and possibly syslog */
1417	bb_error_msg("started, v"BB_VER);
1418	/* Set up the signal pipe */
1419	udhcp_sp_setup();
1420	/* We want random_xid to be random... */
1421	srand(monotonic_us());
1422
1423	state = INIT_SELECTING;
1424	udhcp_run_script(NULL, "deconfig");
1425	change_listen_mode(LISTEN_RAW);
1426	packet_num = 0;
1427	timeout = 0;
1428	already_waited_sec = 0;
1429
1430	/* Main event loop. select() waits on signal pipe and possibly
1431	* on sockfd.
1432	* "continue" statements in code below jump to the top of the loop.
1433	*/
1434	for (;;) {
1435	struct timeval tv;
1436	struct dhcp_packet packet;
1437	/* silence "uninitialized!" warning */
1438	unsigned timestamp_before_wait = timestamp_before_wait;
1439
1440	//bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1441
1442	/* Was opening raw or udp socket here
1443	* if (listen_mode != LISTEN_NONE && sockfd < 0),
1444	* but on fast network renew responses return faster
1445	* than we open sockets. Thus this code is moved
1446	* to change_listen_mode(). Thus we open listen socket
1447	* BEFORE we send renew request (see "case BOUND:"). */
1448
1449	max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1450
1451	tv.tv_sec = timeout - already_waited_sec;
1452	tv.tv_usec = 0;
1453	retval = 0;
1454	/* If we already timed out, fall through with retval = 0, else... */
1455	if ((int)tv.tv_sec > 0) {
1456	log1("waiting on select %u seconds", (int)tv.tv_sec);
1457	timestamp_before_wait = (unsigned)monotonic_sec();
1458	retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1459	if (retval < 0) {
1460	/* EINTR? A signal was caught, don't panic */
1461	if (errno == EINTR) {
1462	already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1463	continue;
1464	}
1465	/* Else: an error occured, panic! */
1466	bb_perror_msg_and_die("select");
1467	}
1468	}
1469
1470	/* If timeout dropped to zero, time to become active:
1471	* resend discover/renew/whatever
1472	*/
1473	if (retval == 0) {
1474	/* When running on a bridge, the ifindex may have changed
1475	* (e.g. if member interfaces were added/removed
1476	* or if the status of the bridge changed).
1477	* Refresh ifindex and client_mac:
1478	*/
1479	if (udhcp_read_interface(client_config.interface,
1480	&client_config.ifindex,
1481	NULL,
1482	client_config.client_mac)
1483	) {
1484	goto ret0; /* iface is gone? */
1485	}
1486	if (clientid_mac_ptr)
1487	memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1488
1489	/* We will restart the wait in any case */
1490	already_waited_sec = 0;
1491
1492	switch (state) {
1493	case INIT_SELECTING:
1494	if (!discover_retries || packet_num < discover_retries) {
1495	if (packet_num == 0)
1496	xid = random_xid();
1497	/* broadcast */
1498	send_discover(xid, requested_ip);
1499	timeout = discover_timeout;
1500	packet_num++;
1501	continue;
1502	}
1503	leasefail:
1504	udhcp_run_script(NULL, "leasefail");
1505	#if BB_MMU /* -b is not supported on NOMMU */
1506	if (opt & OPT_b) { /* background if no lease */
1507	bb_error_msg("no lease, forking to background");
1508	client_background();
1509	/* do not background again! */
1510	opt = ((opt & ~OPT_b) | OPT_f);
1511	} else
1512	#endif
1513	if (opt & OPT_n) { /* abort if no lease */
1514	bb_error_msg("no lease, failing");
1515	retval = 1;
1516	goto ret;
1517	}
1518	/* wait before trying again */
1519	timeout = tryagain_timeout;
1520	packet_num = 0;
1521	continue;
1522	case REQUESTING:
1523	if (packet_num < 3) {
1524	/* send broadcast select packet */
1525	send_select(xid, server_addr, requested_ip);
1526	timeout = discover_timeout;
1527	packet_num++;
1528	continue;
1529	}
1530	/* Timed out, go back to init state.
1531	* "discover...select...discover..." loops
1532	* were seen in the wild. Treat them similarly
1533	* to "no response to discover" case */
1534	change_listen_mode(LISTEN_RAW);
1535	state = INIT_SELECTING;
1536	goto leasefail;
1537	case BOUND:
1538	/* 1/2 lease passed, enter renewing state */
1539	state = RENEWING;
1540	client_config.first_secs = 0; /* make secs field count from 0 */
1541	change_listen_mode(LISTEN_KERNEL);
1542	log1("entering renew state");
1543	/* fall right through */
1544	case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1545	case_RENEW_REQUESTED:
1546	case RENEWING:
1547	if (timeout > 60) {
1548	/* send an unicast renew request */
1549	/* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1550	* a new UDP socket for sending inside send_renew.
1551	* I hazard to guess existing listening socket
1552	* is somehow conflicting with it, but why is it
1553	* not deterministic then?! Strange.
1554	* Anyway, it does recover by eventually failing through
1555	* into INIT_SELECTING state.
1556	*/
1557	send_renew(xid, server_addr, requested_ip);
1558	timeout >>= 1;
1559	continue;
1560	}
1561	/* Timed out, enter rebinding state */
1562	log1("entering rebinding state");
1563	state = REBINDING;
1564	/* fall right through */
1565	case REBINDING:
1566	/* Switch to bcast receive */
1567	change_listen_mode(LISTEN_RAW);
1568	/* Lease is *really* about to run out,
1569	* try to find DHCP server using broadcast */
1570	if (timeout > 0) {
1571	/* send a broadcast renew request */
1572	send_renew(xid, 0 /*INADDR_ANY*/, requested_ip);
1573	timeout >>= 1;
1574	continue;
1575	}
1576	/* Timed out, enter init state */
1577	bb_error_msg("lease lost, entering init state");
1578	udhcp_run_script(NULL, "deconfig");
1579	state = INIT_SELECTING;
1580	client_config.first_secs = 0; /* make secs field count from 0 */
1581	/*timeout = 0; - already is */
1582	packet_num = 0;
1583	continue;
1584	/* case RELEASED: */
1585	}
1586	/* yah, I know, *you* say it would never happen */
1587	timeout = INT_MAX;
1588	continue; /* back to main loop */
1589	} /* if select timed out */
1590
1591	/* select() didn't timeout, something happened */
1592
1593	/* Is it a signal? */
1594	/* note: udhcp_sp_read checks FD_ISSET before reading */
1595	switch (udhcp_sp_read(&rfds)) {
1596	case SIGUSR1:
1597	client_config.first_secs = 0; /* make secs field count from 0 */
1598	already_waited_sec = 0;
1599	perform_renew();
1600	if (state == RENEW_REQUESTED) {
1601	/* We might be either on the same network
1602	* (in which case renew might work),
1603	* or we might be on a completely different one
1604	* (in which case renew won't ever succeed).
1605	* For the second case, must make sure timeout
1606	* is not too big, or else we can send
1607	* futile renew requests for hours.
1608	* (Ab)use -A TIMEOUT value (usually 20 sec)
1609	* as a cap on the timeout.
1610	*/
1611	if (timeout > tryagain_timeout)
1612	timeout = tryagain_timeout;
1613	goto case_RENEW_REQUESTED;
1614	}
1615	/* Start things over */
1616	packet_num = 0;
1617	/* Kill any timeouts, user wants this to hurry along */
1618	timeout = 0;
1619	continue;
1620	case SIGUSR2:
1621	perform_release(server_addr, requested_ip);
1622	timeout = INT_MAX;
1623	continue;
1624	case SIGTERM:
1625	bb_error_msg("received %s", "SIGTERM");
1626	goto ret0;
1627	}
1628
1629	/* Is it a packet? */
1630	if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1631	continue; /* no */
1632
1633	{
1634	int len;
1635
1636	/* A packet is ready, read it */
1637	if (listen_mode == LISTEN_KERNEL)
1638	len = udhcp_recv_kernel_packet(&packet, sockfd);
1639	else
1640	len = udhcp_recv_raw_packet(&packet, sockfd);
1641	if (len == -1) {
1642	/* Error is severe, reopen socket */
1643	bb_error_msg("read error: %s, reopening socket", strerror(errno));
1644	sleep(discover_timeout); /* 3 seconds by default */
1645	change_listen_mode(listen_mode); /* just close and reopen */
1646	}
1647	/* If this packet will turn out to be unrelated/bogus,
1648	* we will go back and wait for next one.
1649	* Be sure timeout is properly decreased. */
1650	already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1651	if (len < 0)
1652	continue;
1653	}
1654
1655	if (packet.xid != xid) {
1656	log1("xid %x (our is %x), ignoring packet",
1657	(unsigned)packet.xid, (unsigned)xid);
1658	continue;
1659	}
1660
1661	/* Ignore packets that aren't for us */
1662	if (packet.hlen != 6
1663	|| memcmp(packet.chaddr, client_config.client_mac, 6) != 0
1664	) {
1665	//FIXME: need to also check that last 10 bytes are zero
1666	log1("chaddr does not match, ignoring packet"); // log2?
1667	continue;
1668	}
1669
1670	message = udhcp_get_option(&packet, DHCP_MESSAGE_TYPE);
1671	if (message == NULL) {
1672	bb_error_msg("no message type option, ignoring packet");
1673	continue;
1674	}
1675
1676	switch (state) {
1677	case INIT_SELECTING:
1678	/* Must be a DHCPOFFER */
1679	if (*message == DHCPOFFER) {
1680	uint8_t *temp;
1681
1682	/* What exactly is server's IP? There are several values.
1683	* Example DHCP offer captured with tchdump:
1684	*
1685	* 10.34.25.254:67 > 10.34.25.202:68 // IP header's src
1686	* BOOTP fields:
1687	* Your-IP 10.34.25.202
1688	* Server-IP 10.34.32.125 // "next server" IP
1689	* Gateway-IP 10.34.25.254 // relay's address (if DHCP relays are in use)
1690	* DHCP options:
1691	* DHCP-Message Option 53, length 1: Offer
1692	* Server-ID Option 54, length 4: 10.34.255.7 // "server ID"
1693	* Default-Gateway Option 3, length 4: 10.34.25.254 // router
1694	*
1695	* We think that real server IP (one to use in renew/release)
1696	* is one in Server-ID option. But I am not 100% sure.
1697	* IP header's src and Gateway-IP (same in this example)
1698	* might work too.
1699	* "Next server" and router are definitely wrong ones to use, though...
1700	*/
1701	/* We used to ignore pcakets without DHCP_SERVER_ID.
1702	* I've got user reports from people who run "address-less" servers.
1703	* They either supply DHCP_SERVER_ID of 0.0.0.0 or don't supply it at all.
1704	* They say ISC DHCP client supports this case.
1705	*/
1706	server_addr = 0;
1707	temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1708	if (!temp) {
1709	bb_error_msg("no server ID, using 0.0.0.0");
1710	} else {
1711	/* it IS unaligned sometimes, don't "optimize" */
1712	move_from_unaligned32(server_addr, temp);
1713	}
1714	/*xid = packet.xid; - already is */
1715	requested_ip = packet.yiaddr;
1716
1717	/* enter requesting state */
1718	state = REQUESTING;
1719	timeout = 0;
1720	packet_num = 0;
1721	already_waited_sec = 0;
1722	}
1723	continue;
1724	case REQUESTING:
1725	case RENEWING:
1726	case RENEW_REQUESTED:
1727	case REBINDING:
1728	if (*message == DHCPACK) {
1729	unsigned start;
1730	uint32_t lease_seconds;
1731	struct in_addr temp_addr;
1732	uint8_t *temp;
1733
1734	temp = udhcp_get_option(&packet, DHCP_LEASE_TIME);
1735	if (!temp) {
1736	bb_error_msg("no lease time with ACK, using 1 hour lease");
1737	lease_seconds = 60 * 60;
1738	} else {
1739	/* it IS unaligned sometimes, don't "optimize" */
1740	move_from_unaligned32(lease_seconds, temp);
1741	lease_seconds = ntohl(lease_seconds);
1742	/* paranoia: must not be too small and not prone to overflows */
1743	if (lease_seconds < 0x10)
1744	lease_seconds = 0x10;
1745	if (lease_seconds >= 0x10000000)
1746	lease_seconds = 0x0fffffff;
1747	}
1748	#if ENABLE_FEATURE_UDHCPC_ARPING
1749	if (opt & OPT_a) {
1750	/* RFC 2131 3.1 paragraph 5:
1751	* "The client receives the DHCPACK message with configuration
1752	* parameters. The client SHOULD perform a final check on the
1753	* parameters (e.g., ARP for allocated network address), and notes
1754	* the duration of the lease specified in the DHCPACK message. At this
1755	* point, the client is configured. If the client detects that the
1756	* address is already in use (e.g., through the use of ARP),
1757	* the client MUST send a DHCPDECLINE message to the server and restarts
1758	* the configuration process..." */
1759	if (!arpping(packet.yiaddr,
1760	NULL,
1761	(uint32_t) 0,
1762	client_config.client_mac,
1763	client_config.interface,
1764	arpping_ms)
1765	) {
1766	bb_error_msg("offered address is in use "
1767	"(got ARP reply), declining");
1768	send_decline(/*xid,*/ server_addr, packet.yiaddr);
1769
1770	if (state != REQUESTING)
1771	udhcp_run_script(NULL, "deconfig");
1772	change_listen_mode(LISTEN_RAW);
1773	state = INIT_SELECTING;
1774	client_config.first_secs = 0; /* make secs field count from 0 */
1775	requested_ip = 0;
1776	timeout = tryagain_timeout;
1777	packet_num = 0;
1778	already_waited_sec = 0;
1779	continue; /* back to main loop */
1780	}
1781	}
1782	#endif
1783	/* enter bound state */
1784	temp_addr.s_addr = packet.yiaddr;
1785	bb_error_msg("lease of %s obtained, lease time %u",
1786	inet_ntoa(temp_addr), (unsigned)lease_seconds);
1787	requested_ip = packet.yiaddr;
1788
1789	start = monotonic_sec();
1790	udhcp_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1791	already_waited_sec = (unsigned)monotonic_sec() - start;
1792	timeout = lease_seconds / 2;
1793	if ((unsigned)timeout < already_waited_sec) {
1794	/* Something went wrong. Back to discover state */
1795	timeout = already_waited_sec = 0;
1796	}
1797
1798	state = BOUND;
1799	change_listen_mode(LISTEN_NONE);
1800	if (opt & OPT_q) { /* quit after lease */
1801	goto ret0;
1802	}
1803	/* future renew failures should not exit (JM) */
1804	opt &= ~OPT_n;
1805	#if BB_MMU /* NOMMU case backgrounded earlier */
1806	if (!(opt & OPT_f)) {
1807	client_background();
1808	/* do not background again! */
1809	opt = ((opt & ~OPT_b) | OPT_f);
1810	}
1811	#endif
1812	/* make future renew packets use different xid */
1813	/* xid = random_xid(); ...but why bother? */
1814
1815	continue; /* back to main loop */
1816	}
1817	if (*message == DHCPNAK) {
1818	/* If network has more than one DHCP server,
1819	* "wrong" server can reply first, with a NAK.
1820	* Do not interpret it as a NAK from "our" server.
1821	*/
1822	if (server_addr != 0) {
1823	uint32_t svid;
1824	uint8_t *temp;
1825
1826	temp = udhcp_get_option(&packet, DHCP_SERVER_ID);
1827	if (!temp) {
1828	non_matching_svid:
1829	log1("received DHCP NAK with wrong"
1830	" server ID, ignoring packet");
1831	continue;
1832	}
1833	move_from_unaligned32(svid, temp);
1834	if (svid != server_addr)
1835	goto non_matching_svid;
1836	}
1837	/* return to init state */
1838	bb_error_msg("received %s", "DHCP NAK");
1839	udhcp_run_script(&packet, "nak");
1840	if (state != REQUESTING)
1841	udhcp_run_script(NULL, "deconfig");
1842	change_listen_mode(LISTEN_RAW);
1843	sleep(3); /* avoid excessive network traffic */
1844	state = INIT_SELECTING;
1845	client_config.first_secs = 0; /* make secs field count from 0 */
1846	requested_ip = 0;
1847	timeout = 0;
1848	packet_num = 0;
1849	already_waited_sec = 0;
1850	}
1851	continue;
1852	/* case BOUND: - ignore all packets */
1853	/* case RELEASED: - ignore all packets */
1854	}
1855	/* back to main loop */
1856	} /* for (;;) - main loop ends */
1857
1858	ret0:
1859	if (opt & OPT_R) /* release on quit */
1860	perform_release(server_addr, requested_ip);
1861	retval = 0;
1862	ret:
1863	/*if (client_config.pidfile) - remove_pidfile has its own check */
1864	remove_pidfile(client_config.pidfile);
1865	return retval;
1866	}
1867