path: root/networking/udhcp/d6_dhcpc.c (plain)
blob: ddf3412a024c5bff6377a21b10ea9773f5ed5f72

1	/* vi: set sw=4 ts=4: */
2	/*
3	* DHCPv6 client.
4	*
5	* 2011-11.
6	* WARNING: THIS CODE IS INCOMPLETE. IT IS NOWHERE NEAR
7	* TO BE READY FOR PRODUCTION USE.
8	*
9	* Copyright (C) 2011 Denys Vlasenko.
10	*
11	* Licensed under GPLv2, see file LICENSE in this source tree.
12	*/
13
14	//config:config UDHCPC6
15	//config: bool "udhcp client for DHCPv6 (udhcpc6)"
16	//config: default n # not yet ready
17	//config: depends on FEATURE_IPV6
18	//config: help
19	//config: udhcpc6 is a DHCPv6 client
20
21	//applet:IF_UDHCPC6(APPLET(udhcpc6, BB_DIR_USR_BIN, BB_SUID_DROP))
22
23	//kbuild:lib-$(CONFIG_UDHCPC6) += d6_dhcpc.o d6_packet.o d6_socket.o common.o socket.o signalpipe.o
24
25
26	#include <syslog.h>
27	/* Override ENABLE_FEATURE_PIDFILE - ifupdown needs our pidfile to always exist */
28	#define WANT_PIDFILE 1
29	#include "common.h"
30	#include "dhcpd.h"
31	#include "dhcpc.h"
32	#include "d6_common.h"
33
34	#include <netinet/if_ether.h>
35	#include <netpacket/packet.h>
36	#include <linux/filter.h>
37
38	/* "struct client_config_t client_config" is in bb_common_bufsiz1 */
39
40
41	#if ENABLE_LONG_OPTS
42	static const char udhcpc6_longopts[] ALIGN1 =
43	"interface\0" Required_argument "i"
44	"now\0" No_argument "n"
45	"pidfile\0" Required_argument "p"
46	"quit\0" No_argument "q"
47	"release\0" No_argument "R"
48	"request\0" Required_argument "r"
49	"script\0" Required_argument "s"
50	"timeout\0" Required_argument "T"
51	"retries\0" Required_argument "t"
52	"tryagain\0" Required_argument "A"
53	"syslog\0" No_argument "S"
54	"request-option\0" Required_argument "O"
55	"no-default-options\0" No_argument "o"
56	"foreground\0" No_argument "f"
57	"background\0" No_argument "b"
58	/// IF_FEATURE_UDHCPC_ARPING("arping\0" No_argument "a")
59	IF_FEATURE_UDHCP_PORT("client-port\0" Required_argument "P")
60	;
61	#endif
62	/* Must match getopt32 option string order */
63	enum {
64	OPT_i = 1 << 0,
65	OPT_n = 1 << 1,
66	OPT_p = 1 << 2,
67	OPT_q = 1 << 3,
68	OPT_R = 1 << 4,
69	OPT_r = 1 << 5,
70	OPT_s = 1 << 6,
71	OPT_T = 1 << 7,
72	OPT_t = 1 << 8,
73	OPT_S = 1 << 9,
74	OPT_A = 1 << 10,
75	OPT_O = 1 << 11,
76	OPT_o = 1 << 12,
77	OPT_x = 1 << 13,
78	OPT_f = 1 << 14,
79	/* The rest has variable bit positions, need to be clever */
80	OPTBIT_f = 14,
81	USE_FOR_MMU( OPTBIT_b,)
82	///IF_FEATURE_UDHCPC_ARPING(OPTBIT_a,)
83	IF_FEATURE_UDHCP_PORT( OPTBIT_P,)
84	USE_FOR_MMU( OPT_b = 1 << OPTBIT_b,)
85	///IF_FEATURE_UDHCPC_ARPING(OPT_a = 1 << OPTBIT_a,)
86	IF_FEATURE_UDHCP_PORT( OPT_P = 1 << OPTBIT_P,)
87	};
88
89
90	/*** Utility functions ***/
91
92	static void *d6_find_option(uint8_t *option, uint8_t *option_end, unsigned code)
93	{
94	/* "length minus 4" */
95	int len_m4 = option_end - option - 4;
96	while (len_m4 >= 0) {
97	/* Next option's len is too big? */
98	if (option[3] > len_m4)
99	return NULL; /* yes. bogus packet! */
100	/* So far we treat any opts with code >255
101	* or len >255 as bogus, and stop at once.
102	* This simplifies big-endian handling.
103	*/
104	if (option[0] != 0 || option[2] != 0)
105	return NULL;
106	/* Option seems to be valid */
107	/* Does its code match? */
108	if (option[1] == code)
109	return option; /* yes! */
110	option += option[3] + 4;
111	len_m4 -= option[3] + 4;
112	}
113	return NULL;
114	}
115
116	static void *d6_copy_option(uint8_t *option, uint8_t *option_end, unsigned code)
117	{
118	uint8_t *opt = d6_find_option(option, option_end, code);
119	if (!opt)
120	return opt;
121	return xmemdup(opt, opt[3] + 4);
122	}
123
124	static void *d6_store_blob(void *dst, const void *src, unsigned len)
125	{
126	memcpy(dst, src, len);
127	return dst + len;
128	}
129
130
131	/*** Script execution code ***/
132
133	static char** new_env(void)
134	{
135	client6_data.env_ptr = xrealloc_vector(client6_data.env_ptr, 3, client6_data.env_idx);
136	return &client6_data.env_ptr[client6_data.env_idx++];
137	}
138
139	/* put all the parameters into the environment */
140	static void option_to_env(uint8_t *option, uint8_t *option_end)
141	{
142	/* "length minus 4" */
143	int len_m4 = option_end - option - 4;
144	while (len_m4 >= 0) {
145	uint32_t v32;
146	char ipv6str[sizeof("ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")];
147
148	if (option[0] != 0 || option[2] != 0)
149	break;
150
151	switch (option[1]) {
152	//case D6_OPT_CLIENTID:
153	//case D6_OPT_SERVERID:
154	case D6_OPT_IA_NA:
155	case D6_OPT_IA_PD:
156	option_to_env(option + 16, option + 4 + option[3]);
157	break;
158	//case D6_OPT_IA_TA:
159	case D6_OPT_IAADDR:
160	/* 0 1 2 3
161	* 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
162	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
163	* | OPTION_IAADDR | option-len |
164	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
165	* | |
166	* | IPv6 address |
167	* | |
168	* | |
169	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
170	* | preferred-lifetime |
171	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
172	* | valid-lifetime |
173	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
174	*/
175	sprint_nip6(ipv6str, option + 4);
176	*new_env() = xasprintf("ipv6=%s", ipv6str);
177
178	move_from_unaligned32(v32, option + 4 + 16 + 4);
179	*new_env() = xasprintf("lease=%u", (unsigned)v32);
180	break;
181
182	//case D6_OPT_ORO:
183	//case D6_OPT_PREFERENCE:
184	//case D6_OPT_ELAPSED_TIME:
185	//case D6_OPT_RELAY_MSG:
186	//case D6_OPT_AUTH:
187	//case D6_OPT_UNICAST:
188	//case D6_OPT_STATUS_CODE:
189	//case D6_OPT_RAPID_COMMIT:
190	//case D6_OPT_USER_CLASS:
191	//case D6_OPT_VENDOR_CLASS:
192	//case D6_OPT_VENDOR_OPTS:
193	//case D6_OPT_INTERFACE_ID:
194	//case D6_OPT_RECONF_MSG:
195	//case D6_OPT_RECONF_ACCEPT:
196
197	case D6_OPT_IAPREFIX:
198	/* 0 1 2 3
199	* 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
200	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
201	* | OPTION_IAPREFIX | option-length |
202	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
203	* | preferred-lifetime |
204	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
205	* | valid-lifetime |
206	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
207	* | prefix-length | |
208	* +-+-+-+-+-+-+-+-+ IPv6 prefix |
209	* | (16 octets) |
210	* | |
211	* | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
212	* | |
213	* +-+-+-+-+-+-+-+-+
214	*/
215	//move_from_unaligned32(v32, option + 4 + 4);
216	//*new_env() = xasprintf("lease=%u", (unsigned)v32);
217
218	sprint_nip6(ipv6str, option + 4 + 4 + 1);
219	*new_env() = xasprintf("ipv6prefix=%s/%u", ipv6str, (unsigned)(option[4 + 4]));
220	}
221	option += 4 + option[3];
222	len_m4 -= 4 + option[3];
223	}
224	}
225
226	static char **fill_envp(struct d6_packet *packet)
227	{
228	char **envp, **curr;
229
230	client6_data.env_ptr = NULL;
231	client6_data.env_idx = 0;
232
233	*new_env() = xasprintf("interface=%s", client_config.interface);
234
235	if (packet)
236	option_to_env(packet->d6_options, packet->d6_options + sizeof(packet->d6_options));
237
238	envp = curr = client6_data.env_ptr;
239	while (*curr)
240	putenv(*curr++);
241
242	return envp;
243	}
244
245	/* Call a script with a par file and env vars */
246	static void d6_run_script(struct d6_packet *packet, const char *name)
247	{
248	char **envp, **curr;
249	char *argv[3];
250
251	envp = fill_envp(packet);
252
253	/* call script */
254	log1("executing %s %s", client_config.script, name);
255	argv[0] = (char*) client_config.script;
256	argv[1] = (char*) name;
257	argv[2] = NULL;
258	spawn_and_wait(argv);
259
260	for (curr = envp; *curr; curr++) {
261	log2(" %s", *curr);
262	bb_unsetenv_and_free(*curr);
263	}
264	free(envp);
265	}
266
267
268	/*** Sending/receiving packets ***/
269
270	static ALWAYS_INLINE uint32_t random_xid(void)
271	{
272	uint32_t t = rand() & htonl(0x00ffffff);
273	return t;
274	}
275
276	/* Initialize the packet with the proper defaults */
277	static uint8_t *init_d6_packet(struct d6_packet *packet, char type, uint32_t xid)
278	{
279	struct d6_option *clientid;
280
281	memset(packet, 0, sizeof(*packet));
282
283	packet->d6_xid32 = xid;
284	packet->d6_msg_type = type;
285
286	clientid = (void*)client_config.clientid;
287	return d6_store_blob(packet->d6_options, clientid, clientid->len + 2+2);
288	}
289
290	static uint8_t *add_d6_client_options(uint8_t *ptr)
291	{
292	return ptr;
293	//uint8_t c;
294	//int i, end, len;
295
296	/* Add a "param req" option with the list of options we'd like to have
297	* from stubborn DHCP servers. Pull the data from the struct in common.c.
298	* No bounds checking because it goes towards the head of the packet. */
299	//...
300
301	/* Add -x options if any */
302	//...
303	}
304
305	static int d6_mcast_from_client_config_ifindex(struct d6_packet *packet, uint8_t *end)
306	{
307	static const uint8_t FF02__1_2[16] = {
308	0xFF, 0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
309	0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x00, 0x02,
310	};
311
312	return d6_send_raw_packet(
313	packet, (end - (uint8_t*) packet),
314	/*src*/ NULL, CLIENT_PORT6,
315	/*dst*/ (struct in6_addr*)FF02__1_2, SERVER_PORT6, MAC_BCAST_ADDR,
316	client_config.ifindex
317	);
318	}
319
320	/* Milticast a DHCPv6 Solicit packet to the network, with an optionally requested IP.
321	*
322	* RFC 3315 17.1.1. Creation of Solicit Messages
323	*
324	* The client MUST include a Client Identifier option to identify itself
325	* to the server. The client includes IA options for any IAs to which
326	* it wants the server to assign addresses. The client MAY include
327	* addresses in the IAs as a hint to the server about addresses for
328	* which the client has a preference. ...
329	*
330	* The client uses IA_NA options to request the assignment of non-
331	* temporary addresses and uses IA_TA options to request the assignment
332	* of temporary addresses. Either IA_NA or IA_TA options, or a
333	* combination of both, can be included in DHCP messages.
334	*
335	* The client SHOULD include an Option Request option (see section 22.7)
336	* to indicate the options the client is interested in receiving. The
337	* client MAY additionally include instances of those options that are
338	* identified in the Option Request option, with data values as hints to
339	* the server about parameter values the client would like to have
340	* returned.
341	*
342	* The client includes a Reconfigure Accept option (see section 22.20)
343	* if the client is willing to accept Reconfigure messages from the
344	* server.
345	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
346	| OPTION_CLIENTID | option-len |
347	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
348	. .
349	. DUID .
350	. (variable length) .
351	. .
352	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
353
354
355	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
356	| OPTION_IA_NA | option-len |
357	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
358	| IAID (4 octets) |
359	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
360	| T1 |
361	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
362	| T2 |
363	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
364	| |
365	. IA_NA-options .
366	. .
367	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
368
369
370	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
371	| OPTION_IAADDR | option-len |
372	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
373	| |
374	| IPv6 address |
375	| |
376	| |
377	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
378	| preferred-lifetime |
379	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
380	| valid-lifetime |
381	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
382	. .
383	. IAaddr-options .
384	. .
385	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
386
387
388	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
389	| OPTION_ORO | option-len |
390	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
391	| requested-option-code-1 | requested-option-code-2 |
392	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
393	| ... |
394	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
395
396
397	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
398	| OPTION_RECONF_ACCEPT | 0 |
399	+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
400	*/
401	/* NOINLINE: limit stack usage in caller */
402	static NOINLINE int send_d6_discover(uint32_t xid, struct in6_addr *requested_ipv6)
403	{
404	struct d6_packet packet;
405	uint8_t *opt_ptr;
406	unsigned len;
407
408	/* Fill in: msg type, client id */
409	opt_ptr = init_d6_packet(&packet, D6_MSG_SOLICIT, xid);
410
411	/* Create new IA_NA, optionally with included IAADDR with requested IP */
412	free(client6_data.ia_na);
413	len = requested_ipv6 ? 2+2+4+4+4 + 2+2+16+4+4 : 2+2+4+4+4;
414	client6_data.ia_na = xzalloc(len);
415	client6_data.ia_na->code = D6_OPT_IA_NA;
416	client6_data.ia_na->len = len - 4;
417	*(uint32_t*)client6_data.ia_na->data = rand(); /* IAID */
418	if (requested_ipv6) {
419	struct d6_option *iaaddr = (void*)(client6_data.ia_na->data + 4+4+4);
420	iaaddr->code = D6_OPT_IAADDR;
421	iaaddr->len = 16+4+4;
422	memcpy(iaaddr->data, requested_ipv6, 16);
423	}
424	opt_ptr = d6_store_blob(opt_ptr, client6_data.ia_na, len);
425
426	/* Add options:
427	* "param req" option according to -O, options specified with -x
428	*/
429	opt_ptr = add_d6_client_options(opt_ptr);
430
431	bb_error_msg("sending %s", "discover");
432	return d6_mcast_from_client_config_ifindex(&packet, opt_ptr);
433	}
434
435	/* Multicast a DHCPv6 request message
436	*
437	* RFC 3315 18.1.1. Creation and Transmission of Request Messages
438	*
439	* The client uses a Request message to populate IAs with addresses and
440	* obtain other configuration information. The client includes one or
441	* more IA options in the Request message. The server then returns
442	* addresses and other information about the IAs to the client in IA
443	* options in a Reply message.
444	*
445	* The client generates a transaction ID and inserts this value in the
446	* "transaction-id" field.
447	*
448	* The client places the identifier of the destination server in a
449	* Server Identifier option.
450	*
451	* The client MUST include a Client Identifier option to identify itself
452	* to the server. The client adds any other appropriate options,
453	* including one or more IA options (if the client is requesting that
454	* the server assign it some network addresses).
455	*
456	* The client MUST include an Option Request option (see section 22.7)
457	* to indicate the options the client is interested in receiving. The
458	* client MAY include options with data values as hints to the server
459	* about parameter values the client would like to have returned.
460	*
461	* The client includes a Reconfigure Accept option (see section 22.20)
462	* indicating whether or not the client is willing to accept Reconfigure
463	* messages from the server.
464	*/
465	/* NOINLINE: limit stack usage in caller */
466	static NOINLINE int send_d6_select(uint32_t xid)
467	{
468	struct d6_packet packet;
469	uint8_t *opt_ptr;
470
471	/* Fill in: msg type, client id */
472	opt_ptr = init_d6_packet(&packet, D6_MSG_REQUEST, xid);
473
474	/* server id */
475	opt_ptr = d6_store_blob(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2);
476	/* IA NA (contains requested IP) */
477	opt_ptr = d6_store_blob(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
478
479	/* Add options:
480	* "param req" option according to -O, options specified with -x
481	*/
482	opt_ptr = add_d6_client_options(opt_ptr);
483
484	bb_error_msg("sending %s", "select");
485	return d6_mcast_from_client_config_ifindex(&packet, opt_ptr);
486	}
487
488	/* Unicast or broadcast a DHCP renew message
489	*
490	* RFC 3315 18.1.3. Creation and Transmission of Renew Messages
491	*
492	* To extend the valid and preferred lifetimes for the addresses
493	* associated with an IA, the client sends a Renew message to the server
494	* from which the client obtained the addresses in the IA containing an
495	* IA option for the IA. The client includes IA Address options in the
496	* IA option for the addresses associated with the IA. The server
497	* determines new lifetimes for the addresses in the IA according to the
498	* administrative configuration of the server. The server may also add
499	* new addresses to the IA. The server may remove addresses from the IA
500	* by setting the preferred and valid lifetimes of those addresses to
501	* zero.
502	*
503	* The server controls the time at which the client contacts the server
504	* to extend the lifetimes on assigned addresses through the T1 and T2
505	* parameters assigned to an IA.
506	*
507	* At time T1 for an IA, the client initiates a Renew/Reply message
508	* exchange to extend the lifetimes on any addresses in the IA. The
509	* client includes an IA option with all addresses currently assigned to
510	* the IA in its Renew message.
511	*
512	* If T1 or T2 is set to 0 by the server (for an IA_NA) or there are no
513	* T1 or T2 times (for an IA_TA), the client may send a Renew or Rebind
514	* message, respectively, at the client's discretion.
515	*
516	* The client sets the "msg-type" field to RENEW. The client generates
517	* a transaction ID and inserts this value in the "transaction-id"
518	* field.
519	*
520	* The client places the identifier of the destination server in a
521	* Server Identifier option.
522	*
523	* The client MUST include a Client Identifier option to identify itself
524	* to the server. The client adds any appropriate options, including
525	* one or more IA options. The client MUST include the list of
526	* addresses the client currently has associated with the IAs in the
527	* Renew message.
528	*
529	* The client MUST include an Option Request option (see section 22.7)
530	* to indicate the options the client is interested in receiving. The
531	* client MAY include options with data values as hints to the server
532	* about parameter values the client would like to have returned.
533	*/
534	/* NOINLINE: limit stack usage in caller */
535	static NOINLINE int send_d6_renew(uint32_t xid, struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
536	{
537	struct d6_packet packet;
538	uint8_t *opt_ptr;
539
540	/* Fill in: msg type, client id */
541	opt_ptr = init_d6_packet(&packet, DHCPREQUEST, xid);
542
543	/* server id */
544	opt_ptr = d6_store_blob(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2);
545	/* IA NA (contains requested IP) */
546	opt_ptr = d6_store_blob(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
547
548	/* Add options:
549	* "param req" option according to -O, options specified with -x
550	*/
551	opt_ptr = add_d6_client_options(opt_ptr);
552
553	bb_error_msg("sending %s", "renew");
554	if (server_ipv6)
555	return d6_send_kernel_packet(
556	&packet, (opt_ptr - (uint8_t*) &packet),
557	our_cur_ipv6, CLIENT_PORT6,
558	server_ipv6, SERVER_PORT6
559	);
560	return d6_mcast_from_client_config_ifindex(&packet, opt_ptr);
561	}
562
563	/* Unicast a DHCP release message */
564	static int send_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
565	{
566	struct d6_packet packet;
567	uint8_t *opt_ptr;
568
569	/* Fill in: msg type, client id */
570	opt_ptr = init_d6_packet(&packet, D6_MSG_RELEASE, random_xid());
571	/* server id */
572	opt_ptr = d6_store_blob(opt_ptr, client6_data.server_id, client6_data.server_id->len + 2+2);
573	/* IA NA (contains our current IP) */
574	opt_ptr = d6_store_blob(opt_ptr, client6_data.ia_na, client6_data.ia_na->len + 2+2);
575
576	bb_error_msg("sending %s", "release");
577	return d6_send_kernel_packet(
578	&packet, (opt_ptr - (uint8_t*) &packet),
579	our_cur_ipv6, CLIENT_PORT6,
580	server_ipv6, SERVER_PORT6
581	);
582	}
583
584	/* Returns -1 on errors that are fatal for the socket, -2 for those that aren't */
585	/* NOINLINE: limit stack usage in caller */
586	static NOINLINE int d6_recv_raw_packet(struct in6_addr *peer_ipv6
587	UNUSED_PARAM
588	, struct d6_packet *d6_pkt, int fd)
589	{
590	int bytes;
591	struct ip6_udp_d6_packet packet;
592
593	bytes = safe_read(fd, &packet, sizeof(packet));
594	if (bytes < 0) {
595	log1("packet read error, ignoring");
596	/* NB: possible down interface, etc. Caller should pause. */
597	return bytes; /* returns -1 */
598	}
599
600	if (bytes < (int) (sizeof(packet.ip6) + sizeof(packet.udp))) {
601	log1("packet is too short, ignoring");
602	return -2;
603	}
604
605	if (bytes < sizeof(packet.ip6) + ntohs(packet.ip6.ip6_plen)) {
606	/* packet is bigger than sizeof(packet), we did partial read */
607	log1("oversized packet, ignoring");
608	return -2;
609	}
610
611	/* ignore any extra garbage bytes */
612	bytes = sizeof(packet.ip6) + ntohs(packet.ip6.ip6_plen);
613
614	/* make sure its the right packet for us, and that it passes sanity checks */
615	if (packet.ip6.ip6_nxt != IPPROTO_UDP
616	|| (packet.ip6.ip6_vfc >> 4) != 6
617	|| packet.udp.dest != htons(CLIENT_PORT6)
618	/* || bytes > (int) sizeof(packet) - can't happen */
619	|| packet.udp.len != packet.ip6.ip6_plen
620	) {
621	log1("unrelated/bogus packet, ignoring");
622	return -2;
623	}
624
625	//How to do this for ipv6?
626	// /* verify UDP checksum. IP header has to be modified for this */
627	// memset(&packet.ip, 0, offsetof(struct iphdr, protocol));
628	// /* ip.xx fields which are not memset: protocol, check, saddr, daddr */
629	// packet.ip.tot_len = packet.udp.len; /* yes, this is needed */
630	// check = packet.udp.check;
631	// packet.udp.check = 0;
632	// if (check && check != inet_cksum((uint16_t *)&packet, bytes)) {
633	// log1("packet with bad UDP checksum received, ignoring");
634	// return -2;
635	// }
636
637	log1("received %s", "a packet");
638	d6_dump_packet(&packet.data);
639
640	bytes -= sizeof(packet.ip6) + sizeof(packet.udp);
641	memcpy(d6_pkt, &packet.data, bytes);
642	return bytes;
643	}
644
645
646	/*** Main ***/
647
648	static int sockfd = -1;
649
650	#define LISTEN_NONE 0
651	#define LISTEN_KERNEL 1
652	#define LISTEN_RAW 2
653	static smallint listen_mode;
654
655	/* initial state: (re)start DHCP negotiation */
656	#define INIT_SELECTING 0
657	/* discover was sent, DHCPOFFER reply received */
658	#define REQUESTING 1
659	/* select/renew was sent, DHCPACK reply received */
660	#define BOUND 2
661	/* half of lease passed, want to renew it by sending unicast renew requests */
662	#define RENEWING 3
663	/* renew requests were not answered, lease is almost over, send broadcast renew */
664	#define REBINDING 4
665	/* manually requested renew (SIGUSR1) */
666	#define RENEW_REQUESTED 5
667	/* release, possibly manually requested (SIGUSR2) */
668	#define RELEASED 6
669	static smallint state;
670
671	static int d6_raw_socket(int ifindex)
672	{
673	int fd;
674	struct sockaddr_ll sock;
675
676	/*
677	* Comment:
678	*
679	* I've selected not to see LL header, so BPF doesn't see it, too.
680	* The filter may also pass non-IP and non-ARP packets, but we do
681	* a more complete check when receiving the message in userspace.
682	*
683	* and filter shamelessly stolen from:
684	*
685	* http://www.flamewarmaster.de/software/dhcpclient/
686	*
687	* There are a few other interesting ideas on that page (look under
688	* "Motivation"). Use of netlink events is most interesting. Think
689	* of various network servers listening for events and reconfiguring.
690	* That would obsolete sending HUP signals and/or make use of restarts.
691	*
692	* Copyright: 2006, 2007 Stefan Rompf <sux@loplof.de>.
693	* License: GPL v2.
694	*
695	* TODO: make conditional?
696	*/
697	#if 0
698	static const struct sock_filter filter_instr[] = {
699	/* load 9th byte (protocol) */
700	BPF_STMT(BPF_LD|BPF_B|BPF_ABS, 9),
701	/* jump to L1 if it is IPPROTO_UDP, else to L4 */
702	BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, IPPROTO_UDP, 0, 6),
703	/* L1: load halfword from offset 6 (flags and frag offset) */
704	BPF_STMT(BPF_LD|BPF_H|BPF_ABS, 6),
705	/* jump to L4 if any bits in frag offset field are set, else to L2 */
706	BPF_JUMP(BPF_JMP|BPF_JSET|BPF_K, 0x1fff, 4, 0),
707	/* L2: skip IP header (load index reg with header len) */
708	BPF_STMT(BPF_LDX|BPF_B|BPF_MSH, 0),
709	/* load udp destination port from halfword[header_len + 2] */
710	BPF_STMT(BPF_LD|BPF_H|BPF_IND, 2),
711	/* jump to L3 if udp dport is CLIENT_PORT6, else to L4 */
712	BPF_JUMP(BPF_JMP|BPF_JEQ|BPF_K, 68, 0, 1),
713	/* L3: accept packet */
714	BPF_STMT(BPF_RET|BPF_K, 0x7fffffff),
715	/* L4: discard packet */
716	BPF_STMT(BPF_RET|BPF_K, 0),
717	};
718	static const struct sock_fprog filter_prog = {
719	.len = sizeof(filter_instr) / sizeof(filter_instr[0]),
720	/* casting const away: */
721	.filter = (struct sock_filter *) filter_instr,
722	};
723	#endif
724
725	log1("opening raw socket on ifindex %d", ifindex); //log2?
726
727	fd = xsocket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IPV6));
728	log1("got raw socket fd %d", fd); //log2?
729
730	sock.sll_family = AF_PACKET;
731	sock.sll_protocol = htons(ETH_P_IPV6);
732	sock.sll_ifindex = ifindex;
733	xbind(fd, (struct sockaddr *) &sock, sizeof(sock));
734
735	#if 0
736	if (CLIENT_PORT6 == 546) {
737	/* Use only if standard port is in use */
738	/* Ignoring error (kernel may lack support for this) */
739	if (setsockopt(fd, SOL_SOCKET, SO_ATTACH_FILTER, &filter_prog,
740	sizeof(filter_prog)) >= 0)
741	log1("attached filter to raw socket fd %d", fd); // log?
742	}
743	#endif
744
745	log1("created raw socket");
746
747	return fd;
748	}
749
750	static void change_listen_mode(int new_mode)
751	{
752	log1("entering listen mode: %s",
753	new_mode != LISTEN_NONE
754	? (new_mode == LISTEN_KERNEL ? "kernel" : "raw")
755	: "none"
756	);
757
758	listen_mode = new_mode;
759	if (sockfd >= 0) {
760	close(sockfd);
761	sockfd = -1;
762	}
763	if (new_mode == LISTEN_KERNEL)
764	sockfd = udhcp_listen_socket(/*INADDR_ANY,*/ CLIENT_PORT6, client_config.interface);
765	else if (new_mode != LISTEN_NONE)
766	sockfd = d6_raw_socket(client_config.ifindex);
767	/* else LISTEN_NONE: sockfd stays closed */
768	}
769
770	/* Called only on SIGUSR1 */
771	static void perform_renew(void)
772	{
773	bb_error_msg("performing DHCP renew");
774	switch (state) {
775	case BOUND:
776	change_listen_mode(LISTEN_KERNEL);
777	case RENEWING:
778	case REBINDING:
779	state = RENEW_REQUESTED;
780	break;
781	case RENEW_REQUESTED: /* impatient are we? fine, square 1 */
782	d6_run_script(NULL, "deconfig");
783	case REQUESTING:
784	case RELEASED:
785	change_listen_mode(LISTEN_RAW);
786	state = INIT_SELECTING;
787	break;
788	case INIT_SELECTING:
789	break;
790	}
791	}
792
793	static void perform_d6_release(struct in6_addr *server_ipv6, struct in6_addr *our_cur_ipv6)
794	{
795	/* send release packet */
796	if (state == BOUND
797	|| state == RENEWING
798	|| state == REBINDING
799	|| state == RENEW_REQUESTED
800	) {
801	bb_error_msg("unicasting a release");
802	send_d6_release(server_ipv6, our_cur_ipv6); /* unicast */
803	}
804	bb_error_msg("entering released state");
805	/*
806	* We can be here on: SIGUSR2,
807	* or on exit (SIGTERM) and -R "release on quit" is specified.
808	* Users requested to be notified in all cases, even if not in one
809	* of the states above.
810	*/
811	d6_run_script(NULL, "deconfig");
812	change_listen_mode(LISTEN_NONE);
813	state = RELEASED;
814	}
815
816	///static uint8_t* alloc_dhcp_option(int code, const char *str, int extra)
817	///{
818	/// uint8_t *storage;
819	/// int len = strnlen(str, 255);
820	/// storage = xzalloc(len + extra + OPT_DATA);
821	/// storage[OPT_CODE] = code;
822	/// storage[OPT_LEN] = len + extra;
823	/// memcpy(storage + extra + OPT_DATA, str, len);
824	/// return storage;
825	///}
826
827	#if BB_MMU
828	static void client_background(void)
829	{
830	bb_daemonize(0);
831	logmode &= ~LOGMODE_STDIO;
832	/* rewrite pidfile, as our pid is different now */
833	write_pidfile(client_config.pidfile);
834	}
835	#endif
836
837	//usage:#if defined CONFIG_UDHCP_DEBUG && CONFIG_UDHCP_DEBUG >= 1
838	//usage:# define IF_UDHCP_VERBOSE(...) __VA_ARGS__
839	//usage:#else
840	//usage:# define IF_UDHCP_VERBOSE(...)
841	//usage:#endif
842	//usage:#define udhcpc6_trivial_usage
843	//usage: "[-fbnq"IF_UDHCP_VERBOSE("v")"oR] [-i IFACE] [-r IP] [-s PROG] [-p PIDFILE]\n"
844	//usage: " [-x OPT:VAL]... [-O OPT]..." IF_FEATURE_UDHCP_PORT(" [-P N]")
845	//usage:#define udhcpc6_full_usage "\n"
846	//usage: IF_LONG_OPTS(
847	//usage: "\n -i,--interface IFACE Interface to use (default eth0)"
848	//usage: "\n -p,--pidfile FILE Create pidfile"
849	//usage: "\n -s,--script PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
850	//usage: "\n -B,--broadcast Request broadcast replies"
851	//usage: "\n -t,--retries N Send up to N discover packets"
852	//usage: "\n -T,--timeout N Pause between packets (default 3 seconds)"
853	//usage: "\n -A,--tryagain N Wait N seconds after failure (default 20)"
854	//usage: "\n -f,--foreground Run in foreground"
855	//usage: USE_FOR_MMU(
856	//usage: "\n -b,--background Background if lease is not obtained"
857	//usage: )
858	//usage: "\n -n,--now Exit if lease is not obtained"
859	//usage: "\n -q,--quit Exit after obtaining lease"
860	//usage: "\n -R,--release Release IP on exit"
861	//usage: "\n -S,--syslog Log to syslog too"
862	//usage: IF_FEATURE_UDHCP_PORT(
863	//usage: "\n -P,--client-port N Use port N (default 546)"
864	//usage: )
865	////usage: IF_FEATURE_UDHCPC_ARPING(
866	////usage: "\n -a,--arping Use arping to validate offered address"
867	////usage: )
868	//usage: "\n -O,--request-option OPT Request option OPT from server (cumulative)"
869	//usage: "\n -o,--no-default-options Don't request any options (unless -O is given)"
870	//usage: "\n -r,--request IP Request this IP address"
871	//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
872	//usage: "\n Examples of string, numeric, and hex byte opts:"
873	//usage: "\n -x hostname:bbox - option 12"
874	//usage: "\n -x lease:3600 - option 51 (lease time)"
875	//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
876	//usage: IF_UDHCP_VERBOSE(
877	//usage: "\n -v Verbose"
878	//usage: )
879	//usage: )
880	//usage: IF_NOT_LONG_OPTS(
881	//usage: "\n -i IFACE Interface to use (default eth0)"
882	//usage: "\n -p FILE Create pidfile"
883	//usage: "\n -s PROG Run PROG at DHCP events (default "CONFIG_UDHCPC_DEFAULT_SCRIPT")"
884	//usage: "\n -B Request broadcast replies"
885	//usage: "\n -t N Send up to N discover packets"
886	//usage: "\n -T N Pause between packets (default 3 seconds)"
887	//usage: "\n -A N Wait N seconds (default 20) after failure"
888	//usage: "\n -f Run in foreground"
889	//usage: USE_FOR_MMU(
890	//usage: "\n -b Background if lease is not obtained"
891	//usage: )
892	//usage: "\n -n Exit if lease is not obtained"
893	//usage: "\n -q Exit after obtaining lease"
894	//usage: "\n -R Release IP on exit"
895	//usage: "\n -S Log to syslog too"
896	//usage: IF_FEATURE_UDHCP_PORT(
897	//usage: "\n -P N Use port N (default 546)"
898	//usage: )
899	////usage: IF_FEATURE_UDHCPC_ARPING(
900	////usage: "\n -a Use arping to validate offered address"
901	////usage: )
902	//usage: "\n -O OPT Request option OPT from server (cumulative)"
903	//usage: "\n -o Don't request any options (unless -O is given)"
904	//usage: "\n -r IP Request this IP address"
905	//usage: "\n -x OPT:VAL Include option OPT in sent packets (cumulative)"
906	//usage: "\n Examples of string, numeric, and hex byte opts:"
907	//usage: "\n -x hostname:bbox - option 12"
908	//usage: "\n -x lease:3600 - option 51 (lease time)"
909	//usage: "\n -x 0x3d:0100BEEFC0FFEE - option 61 (client id)"
910	//usage: IF_UDHCP_VERBOSE(
911	//usage: "\n -v Verbose"
912	//usage: )
913	//usage: )
914	//usage: "\nSignals:"
915	//usage: "\n USR1 Renew lease"
916	//usage: "\n USR2 Release lease"
917
918
919	int udhcpc6_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
920	int udhcpc6_main(int argc UNUSED_PARAM, char **argv)
921	{
922	const char *str_r;
923	IF_FEATURE_UDHCP_PORT(char *str_P;)
924	void *clientid_mac_ptr;
925	llist_t *list_O = NULL;
926	llist_t *list_x = NULL;
927	int tryagain_timeout = 20;
928	int discover_timeout = 3;
929	int discover_retries = 3;
930	struct in6_addr srv6_buf;
931	struct in6_addr ipv6_buf;
932	struct in6_addr *requested_ipv6;
933	uint32_t xid = 0;
934	int packet_num;
935	int timeout; /* must be signed */
936	unsigned already_waited_sec;
937	unsigned opt;
938	int max_fd;
939	int retval;
940	fd_set rfds;
941
942	setup_common_bufsiz();
943
944	/* Default options */
945	IF_FEATURE_UDHCP_PORT(SERVER_PORT6 = 547;)
946	IF_FEATURE_UDHCP_PORT(CLIENT_PORT6 = 546;)
947	client_config.interface = "eth0";
948	client_config.script = CONFIG_UDHCPC_DEFAULT_SCRIPT;
949
950	/* Parse command line */
951	/* O,x: list; -T,-t,-A take numeric param */
952	IF_UDHCP_VERBOSE(opt_complementary = "vv";)
953	IF_LONG_OPTS(applet_long_options = udhcpc6_longopts;)
954	opt = getopt32(argv, "i:np:qRr:s:T:+t:+SA:+O:*ox:*f"
955	USE_FOR_MMU("b")
956	///IF_FEATURE_UDHCPC_ARPING("a")
957	IF_FEATURE_UDHCP_PORT("P:")
958	"v"
959	, &client_config.interface, &client_config.pidfile, &str_r /* i,p */
960	, &client_config.script /* s */
961	, &discover_timeout, &discover_retries, &tryagain_timeout /* T,t,A */
962	, &list_O
963	, &list_x
964	IF_FEATURE_UDHCP_PORT(, &str_P)
965	IF_UDHCP_VERBOSE(, &dhcp_verbose)
966	);
967	requested_ipv6 = NULL;
968	if (opt & OPT_r) {
969	if (inet_pton(AF_INET6, str_r, &ipv6_buf) <= 0)
970	bb_error_msg_and_die("bad IPv6 address '%s'", str_r);
971	requested_ipv6 = &ipv6_buf;
972	}
973	#if ENABLE_FEATURE_UDHCP_PORT
974	if (opt & OPT_P) {
975	CLIENT_PORT6 = xatou16(str_P);
976	SERVER_PORT6 = CLIENT_PORT6 + 1;
977	}
978	#endif
979	while (list_O) {
980	char *optstr = llist_pop(&list_O);
981	unsigned n = bb_strtou(optstr, NULL, 0);
982	if (errno || n > 254) {
983	n = udhcp_option_idx(optstr);
984	n = dhcp_optflags[n].code;
985	}
986	client_config.opt_mask[n >> 3] |= 1 << (n & 7);
987	}
988	if (!(opt & OPT_o)) {
989	/*
990	unsigned i, n;
991	for (i = 0; (n = dhcp_optflags[i].code) != 0; i++) {
992	if (dhcp_optflags[i].flags & OPTION_REQ) {
993	client_config.opt_mask[n >> 3] |= 1 << (n & 7);
994	}
995	}
996	*/
997	}
998	while (list_x) {
999	char *optstr = llist_pop(&list_x);
1000	char *colon = strchr(optstr, ':');
1001	if (colon)
1002	*colon = ' ';
1003	/* now it looks similar to udhcpd's config file line:
1004	* "optname optval", using the common routine: */
1005	udhcp_str2optset(optstr, &client_config.options);
1006	}
1007
1008	if (udhcp_read_interface(client_config.interface,
1009	&client_config.ifindex,
1010	NULL,
1011	client_config.client_mac)
1012	) {
1013	return 1;
1014	}
1015
1016	/* Create client ID based on mac, set clientid_mac_ptr */
1017	{
1018	struct d6_option *clientid;
1019	clientid = xzalloc(2+2+2+2+6);
1020	clientid->code = D6_OPT_CLIENTID;
1021	clientid->len = 2+2+6;
1022	clientid->data[1] = 3; /* DUID-LL */
1023	clientid->data[3] = 1; /* ethernet */
1024	clientid_mac_ptr = clientid->data + 2+2;
1025	memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1026	client_config.clientid = (void*)clientid;
1027	}
1028
1029	#if !BB_MMU
1030	/* on NOMMU reexec (i.e., background) early */
1031	if (!(opt & OPT_f)) {
1032	bb_daemonize_or_rexec(0 /* flags */, argv);
1033	logmode = LOGMODE_NONE;
1034	}
1035	#endif
1036	if (opt & OPT_S) {
1037	openlog(applet_name, LOG_PID, LOG_DAEMON);
1038	logmode |= LOGMODE_SYSLOG;
1039	}
1040
1041	/* Make sure fd 0,1,2 are open */
1042	bb_sanitize_stdio();
1043	/* Equivalent of doing a fflush after every \n */
1044	setlinebuf(stdout);
1045	/* Create pidfile */
1046	write_pidfile(client_config.pidfile);
1047	/* Goes to stdout (unless NOMMU) and possibly syslog */
1048	bb_error_msg("started, v"BB_VER);
1049	/* Set up the signal pipe */
1050	udhcp_sp_setup();
1051	/* We want random_xid to be random... */
1052	srand(monotonic_us());
1053
1054	state = INIT_SELECTING;
1055	d6_run_script(NULL, "deconfig");
1056	change_listen_mode(LISTEN_RAW);
1057	packet_num = 0;
1058	timeout = 0;
1059	already_waited_sec = 0;
1060
1061	/* Main event loop. select() waits on signal pipe and possibly
1062	* on sockfd.
1063	* "continue" statements in code below jump to the top of the loop.
1064	*/
1065	for (;;) {
1066	struct timeval tv;
1067	struct d6_packet packet;
1068	uint8_t *packet_end;
1069	/* silence "uninitialized!" warning */
1070	unsigned timestamp_before_wait = timestamp_before_wait;
1071
1072	//bb_error_msg("sockfd:%d, listen_mode:%d", sockfd, listen_mode);
1073
1074	/* Was opening raw or udp socket here
1075	* if (listen_mode != LISTEN_NONE && sockfd < 0),
1076	* but on fast network renew responses return faster
1077	* than we open sockets. Thus this code is moved
1078	* to change_listen_mode(). Thus we open listen socket
1079	* BEFORE we send renew request (see "case BOUND:"). */
1080
1081	max_fd = udhcp_sp_fd_set(&rfds, sockfd);
1082
1083	tv.tv_sec = timeout - already_waited_sec;
1084	tv.tv_usec = 0;
1085	retval = 0;
1086	/* If we already timed out, fall through with retval = 0, else... */
1087	if ((int)tv.tv_sec > 0) {
1088	log1("waiting on select %u seconds", (int)tv.tv_sec);
1089	timestamp_before_wait = (unsigned)monotonic_sec();
1090	retval = select(max_fd + 1, &rfds, NULL, NULL, &tv);
1091	if (retval < 0) {
1092	/* EINTR? A signal was caught, don't panic */
1093	if (errno == EINTR) {
1094	already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1095	continue;
1096	}
1097	/* Else: an error occured, panic! */
1098	bb_perror_msg_and_die("select");
1099	}
1100	}
1101
1102	/* If timeout dropped to zero, time to become active:
1103	* resend discover/renew/whatever
1104	*/
1105	if (retval == 0) {
1106	/* When running on a bridge, the ifindex may have changed
1107	* (e.g. if member interfaces were added/removed
1108	* or if the status of the bridge changed).
1109	* Refresh ifindex and client_mac:
1110	*/
1111	if (udhcp_read_interface(client_config.interface,
1112	&client_config.ifindex,
1113	NULL,
1114	client_config.client_mac)
1115	) {
1116	goto ret0; /* iface is gone? */
1117	}
1118	memcpy(clientid_mac_ptr, client_config.client_mac, 6);
1119
1120	/* We will restart the wait in any case */
1121	already_waited_sec = 0;
1122
1123	switch (state) {
1124	case INIT_SELECTING:
1125	if (!discover_retries || packet_num < discover_retries) {
1126	if (packet_num == 0)
1127	xid = random_xid();
1128	/* multicast */
1129	send_d6_discover(xid, requested_ipv6);
1130	timeout = discover_timeout;
1131	packet_num++;
1132	continue;
1133	}
1134	leasefail:
1135	d6_run_script(NULL, "leasefail");
1136	#if BB_MMU /* -b is not supported on NOMMU */
1137	if (opt & OPT_b) { /* background if no lease */
1138	bb_error_msg("no lease, forking to background");
1139	client_background();
1140	/* do not background again! */
1141	opt = ((opt & ~OPT_b) | OPT_f);
1142	} else
1143	#endif
1144	if (opt & OPT_n) { /* abort if no lease */
1145	bb_error_msg("no lease, failing");
1146	retval = 1;
1147	goto ret;
1148	}
1149	/* wait before trying again */
1150	timeout = tryagain_timeout;
1151	packet_num = 0;
1152	continue;
1153	case REQUESTING:
1154	if (!discover_retries || packet_num < discover_retries) {
1155	/* send multicast select packet */
1156	send_d6_select(xid);
1157	timeout = discover_timeout;
1158	packet_num++;
1159	continue;
1160	}
1161	/* Timed out, go back to init state.
1162	* "discover...select...discover..." loops
1163	* were seen in the wild. Treat them similarly
1164	* to "no response to discover" case */
1165	change_listen_mode(LISTEN_RAW);
1166	state = INIT_SELECTING;
1167	goto leasefail;
1168	case BOUND:
1169	/* 1/2 lease passed, enter renewing state */
1170	state = RENEWING;
1171	client_config.first_secs = 0; /* make secs field count from 0 */
1172	change_listen_mode(LISTEN_KERNEL);
1173	log1("entering renew state");
1174	/* fall right through */
1175	case RENEW_REQUESTED: /* manual (SIGUSR1) renew */
1176	case_RENEW_REQUESTED:
1177	case RENEWING:
1178	if (timeout > 60) {
1179	/* send an unicast renew request */
1180	/* Sometimes observed to fail (EADDRNOTAVAIL) to bind
1181	* a new UDP socket for sending inside send_renew.
1182	* I hazard to guess existing listening socket
1183	* is somehow conflicting with it, but why is it
1184	* not deterministic then?! Strange.
1185	* Anyway, it does recover by eventually failing through
1186	* into INIT_SELECTING state.
1187	*/
1188	send_d6_renew(xid, &srv6_buf, requested_ipv6);
1189	timeout >>= 1;
1190	continue;
1191	}
1192	/* Timed out, enter rebinding state */
1193	log1("entering rebinding state");
1194	state = REBINDING;
1195	/* fall right through */
1196	case REBINDING:
1197	/* Switch to bcast receive */
1198	change_listen_mode(LISTEN_RAW);
1199	/* Lease is *really* about to run out,
1200	* try to find DHCP server using broadcast */
1201	if (timeout > 0) {
1202	/* send a broadcast renew request */
1203	send_d6_renew(xid, /*server_ipv6:*/ NULL, requested_ipv6);
1204	timeout >>= 1;
1205	continue;
1206	}
1207	/* Timed out, enter init state */
1208	bb_error_msg("lease lost, entering init state");
1209	d6_run_script(NULL, "deconfig");
1210	state = INIT_SELECTING;
1211	client_config.first_secs = 0; /* make secs field count from 0 */
1212	/*timeout = 0; - already is */
1213	packet_num = 0;
1214	continue;
1215	/* case RELEASED: */
1216	}
1217	/* yah, I know, *you* say it would never happen */
1218	timeout = INT_MAX;
1219	continue; /* back to main loop */
1220	} /* if select timed out */
1221
1222	/* select() didn't timeout, something happened */
1223
1224	/* Is it a signal? */
1225	/* note: udhcp_sp_read checks FD_ISSET before reading */
1226	switch (udhcp_sp_read(&rfds)) {
1227	case SIGUSR1:
1228	client_config.first_secs = 0; /* make secs field count from 0 */
1229	already_waited_sec = 0;
1230	perform_renew();
1231	if (state == RENEW_REQUESTED) {
1232	/* We might be either on the same network
1233	* (in which case renew might work),
1234	* or we might be on a completely different one
1235	* (in which case renew won't ever succeed).
1236	* For the second case, must make sure timeout
1237	* is not too big, or else we can send
1238	* futile renew requests for hours.
1239	* (Ab)use -A TIMEOUT value (usually 20 sec)
1240	* as a cap on the timeout.
1241	*/
1242	if (timeout > tryagain_timeout)
1243	timeout = tryagain_timeout;
1244	goto case_RENEW_REQUESTED;
1245	}
1246	/* Start things over */
1247	packet_num = 0;
1248	/* Kill any timeouts, user wants this to hurry along */
1249	timeout = 0;
1250	continue;
1251	case SIGUSR2:
1252	perform_d6_release(&srv6_buf, requested_ipv6);
1253	timeout = INT_MAX;
1254	continue;
1255	case SIGTERM:
1256	bb_error_msg("received %s", "SIGTERM");
1257	goto ret0;
1258	}
1259
1260	/* Is it a packet? */
1261	if (listen_mode == LISTEN_NONE || !FD_ISSET(sockfd, &rfds))
1262	continue; /* no */
1263
1264	{
1265	int len;
1266
1267	/* A packet is ready, read it */
1268	if (listen_mode == LISTEN_KERNEL)
1269	len = d6_recv_kernel_packet(&srv6_buf, &packet, sockfd);
1270	else
1271	len = d6_recv_raw_packet(&srv6_buf, &packet, sockfd);
1272	if (len == -1) {
1273	/* Error is severe, reopen socket */
1274	bb_error_msg("read error: %s, reopening socket", strerror(errno));
1275	sleep(discover_timeout); /* 3 seconds by default */
1276	change_listen_mode(listen_mode); /* just close and reopen */
1277	}
1278	/* If this packet will turn out to be unrelated/bogus,
1279	* we will go back and wait for next one.
1280	* Be sure timeout is properly decreased. */
1281	already_waited_sec += (unsigned)monotonic_sec() - timestamp_before_wait;
1282	if (len < 0)
1283	continue;
1284	packet_end = (uint8_t*)&packet + len;
1285	}
1286
1287	if ((packet.d6_xid32 & htonl(0x00ffffff)) != xid) {
1288	log1("xid %x (our is %x), ignoring packet",
1289	(unsigned)(packet.d6_xid32 & htonl(0x00ffffff)), (unsigned)xid);
1290	continue;
1291	}
1292
1293	switch (state) {
1294	case INIT_SELECTING:
1295	if (packet.d6_msg_type == D6_MSG_ADVERTISE)
1296	goto type_is_ok;
1297	/* DHCPv6 has "Rapid Commit", when instead of Advertise,
1298	* server sends Reply right away.
1299	* Fall through to check for this case.
1300	*/
1301	case REQUESTING:
1302	case RENEWING:
1303	case RENEW_REQUESTED:
1304	case REBINDING:
1305	if (packet.d6_msg_type == D6_MSG_REPLY) {
1306	uint32_t lease_seconds;
1307	struct d6_option *option, *iaaddr;
1308	type_is_ok:
1309	option = d6_find_option(packet.d6_options, packet_end, D6_OPT_STATUS_CODE);
1310	if (option && option->data[4] != 0) {
1311	/* return to init state */
1312	bb_error_msg("received DHCP NAK (%u)", option->data[4]);
1313	d6_run_script(&packet, "nak");
1314	if (state != REQUESTING)
1315	d6_run_script(NULL, "deconfig");
1316	change_listen_mode(LISTEN_RAW);
1317	sleep(3); /* avoid excessive network traffic */
1318	state = INIT_SELECTING;
1319	client_config.first_secs = 0; /* make secs field count from 0 */
1320	requested_ipv6 = NULL;
1321	timeout = 0;
1322	packet_num = 0;
1323	already_waited_sec = 0;
1324	continue;
1325	}
1326	option = d6_copy_option(packet.d6_options, packet_end, D6_OPT_SERVERID);
1327	if (!option) {
1328	bb_error_msg("no server ID, ignoring packet");
1329	continue;
1330	/* still selecting - this server looks bad */
1331	}
1332	//Note: we do not bother comparing server IDs in Advertise and Reply msgs.
1333	//server_id variable is used solely for creation of proper server_id option
1334	//in outgoing packets. (why DHCPv6 even introduced it is a mystery).
1335	free(client6_data.server_id);
1336	client6_data.server_id = option;
1337	if (packet.d6_msg_type == D6_MSG_ADVERTISE) {
1338	/* enter requesting state */
1339	state = REQUESTING;
1340	timeout = 0;
1341	packet_num = 0;
1342	already_waited_sec = 0;
1343	continue;
1344	}
1345	/* It's a D6_MSG_REPLY */
1346	/*
1347	* RFC 3315 18.1.8. Receipt of Reply Messages
1348	*
1349	* Upon the receipt of a valid Reply message in response to a Solicit
1350	* (with a Rapid Commit option), Request, Confirm, Renew, Rebind or
1351	* Information-request message, the client extracts the configuration
1352	* information contained in the Reply. The client MAY choose to report
1353	* any status code or message from the status code option in the Reply
1354	* message.
1355	*
1356	* The client SHOULD perform duplicate address detection [17] on each of
1357	* the addresses in any IAs it receives in the Reply message before
1358	* using that address for traffic. If any of the addresses are found to
1359	* be in use on the link, the client sends a Decline message to the
1360	* server as described in section 18.1.7.
1361	*
1362	* If the Reply was received in response to a Solicit (with a Rapid
1363	* Commit option), Request, Renew or Rebind message, the client updates
1364	* the information it has recorded about IAs from the IA options
1365	* contained in the Reply message:
1366	*
1367	* - Record T1 and T2 times.
1368	*
1369	* - Add any new addresses in the IA option to the IA as recorded by
1370	* the client.
1371	*
1372	* - Update lifetimes for any addresses in the IA option that the
1373	* client already has recorded in the IA.
1374	*
1375	* - Discard any addresses from the IA, as recorded by the client, that
1376	* have a valid lifetime of 0 in the IA Address option.
1377	*
1378	* - Leave unchanged any information about addresses the client has
1379	* recorded in the IA but that were not included in the IA from the
1380	* server.
1381	*
1382	* Management of the specific configuration information is detailed in
1383	* the definition of each option in section 22.
1384	*
1385	* If the client receives a Reply message with a Status Code containing
1386	* UnspecFail, the server is indicating that it was unable to process
1387	* the message due to an unspecified failure condition. If the client
1388	* retransmits the original message to the same server to retry the
1389	* desired operation, the client MUST limit the rate at which it
1390	* retransmits the message and limit the duration of the time during
1391	* which it retransmits the message.
1392	*
1393	* When the client receives a Reply message with a Status Code option
1394	* with the value UseMulticast, the client records the receipt of the
1395	* message and sends subsequent messages to the server through the
1396	* interface on which the message was received using multicast. The
1397	* client resends the original message using multicast.
1398	*
1399	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1400	* | OPTION_IA_NA | option-len |
1401	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1402	* | IAID (4 octets) |
1403	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1404	* | T1 |
1405	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1406	* | T2 |
1407	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1408	* | |
1409	* . IA_NA-options .
1410	* . .
1411	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1412	*
1413	*
1414	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1415	* | OPTION_IAADDR | option-len |
1416	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1417	* | |
1418	* | IPv6 address |
1419	* | |
1420	* | |
1421	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1422	* | preferred-lifetime |
1423	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1424	* | valid-lifetime |
1425	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1426	* . .
1427	* . IAaddr-options .
1428	* . .
1429	* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
1430	*/
1431	free(client6_data.ia_na);
1432	client6_data.ia_na = d6_copy_option(packet.d6_options, packet_end, D6_OPT_IA_NA);
1433	if (!client6_data.ia_na) {
1434	bb_error_msg("no %s option, ignoring packet", "IA_NA");
1435	continue;
1436	}
1437	if (client6_data.ia_na->len < (4 + 4 + 4) + (2 + 2 + 16 + 4 + 4)) {
1438	bb_error_msg("IA_NA option is too short:%d bytes", client6_data.ia_na->len);
1439	continue;
1440	}
1441	iaaddr = d6_find_option(client6_data.ia_na->data + 4 + 4 + 4,
1442	client6_data.ia_na->data + client6_data.ia_na->len,
1443	D6_OPT_IAADDR
1444	);
1445	if (!iaaddr) {
1446	bb_error_msg("no %s option, ignoring packet", "IAADDR");
1447	continue;
1448	}
1449	if (iaaddr->len < (16 + 4 + 4)) {
1450	bb_error_msg("IAADDR option is too short:%d bytes", iaaddr->len);
1451	continue;
1452	}
1453	/* Note: the address is sufficiently aligned for cast:
1454	* we _copied_ IA-NA, and copy is always well-aligned.
1455	*/
1456	requested_ipv6 = (struct in6_addr*) iaaddr->data;
1457	move_from_unaligned32(lease_seconds, iaaddr->data + 16 + 4);
1458	lease_seconds = ntohl(lease_seconds);
1459	/* paranoia: must not be too small and not prone to overflows */
1460	if (lease_seconds < 0x10)
1461	lease_seconds = 0x10;
1462	/// TODO: check for 0 lease time?
1463	if (lease_seconds >= 0x10000000)
1464	lease_seconds = 0x0fffffff;
1465	/* enter bound state */
1466	timeout = lease_seconds / 2;
1467	bb_error_msg("lease obtained, lease time %u",
1468	/*inet_ntoa(temp_addr),*/ (unsigned)lease_seconds);
1469	d6_run_script(&packet, state == REQUESTING ? "bound" : "renew");
1470
1471	state = BOUND;
1472	change_listen_mode(LISTEN_NONE);
1473	if (opt & OPT_q) { /* quit after lease */
1474	goto ret0;
1475	}
1476	/* future renew failures should not exit (JM) */
1477	opt &= ~OPT_n;
1478	#if BB_MMU /* NOMMU case backgrounded earlier */
1479	if (!(opt & OPT_f)) {
1480	client_background();
1481	/* do not background again! */
1482	opt = ((opt & ~OPT_b) | OPT_f);
1483	}
1484	#endif
1485	already_waited_sec = 0;
1486	continue; /* back to main loop */
1487	}
1488	continue;
1489	/* case BOUND: - ignore all packets */
1490	/* case RELEASED: - ignore all packets */
1491	}
1492	/* back to main loop */
1493	} /* for (;;) - main loop ends */
1494
1495	ret0:
1496	if (opt & OPT_R) /* release on quit */
1497	perform_d6_release(&srv6_buf, requested_ipv6);
1498	retval = 0;
1499	ret:
1500	/*if (client_config.pidfile) - remove_pidfile has its own check */
1501	remove_pidfile(client_config.pidfile);
1502	return retval;
1503	}
1504