summaryrefslogtreecommitdiffstats
path: root/net/dhcp.c
blob: d86f9a9a2bb02a50c49e90e31bd948134630f738 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
/*
 *	Based on LiMon - BOOTP.
 *
 *	Copyright 1994, 1995, 2000 Neil Russell.
 *	(See License)
 *	Copyright 2000 Roland Borde
 *	Copyright 2000 Paolo Scaffardi
 *	Copyright 2000-2004 Wolfgang Denk, wd@denx.de
 */

#include <common.h>
#include <command.h>
#include <environment.h>
#include <clock.h>
#include <net.h>
#include <libbb.h>
#include <errno.h>
#include <magicvar.h>
#include <linux/err.h>

#define OPT_SIZE 312	/* Minimum DHCP Options size per RFC2131 - results in 576 byte pkt */

struct bootp {
	uint8_t		bp_op;		/* Operation				*/
#define OP_BOOTREQUEST	1
#define OP_BOOTREPLY	2
	uint8_t		bp_htype;	/* Hardware type			*/
#define HWT_ETHER	1
	uint8_t		bp_hlen;	/* Hardware address length		*/
#define HWL_ETHER	6
	uint8_t		bp_hops;	/* Hop count (gateway thing)		*/
	uint32_t	bp_id;		/* Transaction ID			*/
	uint16_t	bp_secs;	/* Seconds since boot			*/
	uint16_t	bp_spare1;	/* Alignment				*/
	IPaddr_t	bp_ciaddr;	/* Client IP address			*/
	IPaddr_t	bp_yiaddr;	/* Your (client) IP address		*/
	IPaddr_t	bp_siaddr;	/* Server IP address			*/
	IPaddr_t	bp_giaddr;	/* Gateway IP address			*/
	uint8_t		bp_chaddr[16];	/* Client hardware address		*/
	char		bp_sname[64];	/* Server host name			*/
	char		bp_file[128];	/* Boot file name			*/
	char		bp_vend[0];	/* Vendor information			*/
};

/* DHCP States */
typedef enum {
	INIT,
	INIT_REBOOT,
	REBOOTING,
	SELECTING,
	REQUESTING,
	REBINDING,
	BOUND,
	RENEWING,
} dhcp_state_t;

#define DHCP_DISCOVER 1
#define DHCP_OFFER    2
#define DHCP_REQUEST  3
#define DHCP_DECLINE  4
#define DHCP_ACK      5
#define DHCP_NAK      6
#define DHCP_RELEASE  7

#define BOOTP_VENDOR_MAGIC	0x63825363	/* RFC1048 Magic Cookie		*/

#define PORT_BOOTPS	67		/* BOOTP server UDP port		*/
#define PORT_BOOTPC	68		/* BOOTP client UDP port		*/

#define DHCP_MIN_EXT_LEN 64	/* minimal length of extension list	*/

static uint32_t Bootp_id;
static dhcp_state_t dhcp_state;
static uint32_t dhcp_leasetime;
static IPaddr_t net_dhcp_server_ip;
static uint64_t dhcp_start;

static int bootp_check_packet(unsigned char *pkt, unsigned src, unsigned len)
{
	struct bootp *bp = (struct bootp *) pkt;
	int retval = 0;

	if (src != PORT_BOOTPS)
		retval = -1;
	else if (len < sizeof(struct bootp))
		retval = -2;
	else if (bp->bp_op != OP_BOOTREQUEST &&
	    bp->bp_op != OP_BOOTREPLY &&
	    bp->bp_op != DHCP_OFFER &&
	    bp->bp_op != DHCP_ACK &&
	    bp->bp_op != DHCP_NAK ) {
		retval = -3;
	}
	else if (bp->bp_htype != HWT_ETHER)
		retval = -4;
	else if (bp->bp_hlen != HWL_ETHER)
		retval = -5;
	else if (net_read_uint32(&bp->bp_id) != Bootp_id) {
		retval = -6;
	}

	debug("Filtering pkt = %d\n", retval);

	return retval;
}

/*
 * Copy parameters of interest from BOOTP_REPLY/DHCP_OFFER packet
 */
static void bootp_copy_net_params(struct bootp *bp)
{
	IPaddr_t tmp_ip;

	tmp_ip = net_read_ip(&bp->bp_yiaddr);
	net_set_ip(tmp_ip);

	tmp_ip = net_read_ip(&bp->bp_siaddr);
	if (tmp_ip != 0)
		net_set_serverip(tmp_ip);

	if (strlen(bp->bp_file) > 0)
		setenv("bootfile", bp->bp_file);

	debug("bootfile: %s\n", bp->bp_file);
}

/*
 * Initialize BOOTP extension fields in the request.
 */
static int dhcp_extended (u8 *e, int message_type, IPaddr_t ServerID, IPaddr_t RequestedIP)
{
	u8 *start = e;
	u8 *cnt;

	*e++ = 99;		/* RFC1048 Magic Cookie */
	*e++ = 130;
	*e++ = 83;
	*e++ = 99;

	*e++ = 53;		/* DHCP Message Type */
	*e++ = 1;
	*e++ = message_type;

	*e++ = 57;		/* Maximum DHCP Message Size */
	*e++ = 2;
	*e++ = (576 - 312 + OPT_SIZE) >> 8;
	*e++ = (576 - 312 + OPT_SIZE) & 0xff;

	if (ServerID) {
		int tmp = ntohl (ServerID);

		*e++ = 54;	/* ServerID */
		*e++ = 4;
		*e++ = tmp >> 24;
		*e++ = tmp >> 16;
		*e++ = tmp >> 8;
		*e++ = tmp & 0xff;
	}

	if (RequestedIP) {
		int tmp = ntohl (RequestedIP);

		*e++ = 50;	/* Requested IP */
		*e++ = 4;
		*e++ = tmp >> 24;
		*e++ = tmp >> 16;
		*e++ = tmp >> 8;
		*e++ = tmp & 0xff;
	}

	*e++ = 55;		/* Parameter Request List */
	 cnt = e++;		/* Pointer to count of requested items */
	*cnt = 0;
	*e++  = 1;		/* Subnet Mask */
	*cnt += 1;
	*e++  = 3;		/* Router Option */
	*cnt += 1;
	*e++  = 6;		/* DNS Server(s) */
	*cnt += 1;
	*e++  = 12;		/* Hostname */
	*cnt += 1;
	*e++  = 15;		/* domain name */
	*cnt += 1;
	*e++  = 17;		/* Boot path */
	*cnt += 1;
	*e++  = 255;		/* End of the list */

	/* Pad to minimal length */
	while ((e - start) <= DHCP_MIN_EXT_LEN)
		*e++ = 0;

	return e - start;
}

static struct net_connection *dhcp_con;

static int bootp_request(void)
{
	struct bootp *bp;
	int ext_len;
	int ret;
	unsigned char *payload = net_udp_get_payload(dhcp_con);
	const char *bfile;

	dhcp_state = INIT;

	debug("BOOTP broadcast\n");

	bp = (struct bootp *)payload;
	bp->bp_op = OP_BOOTREQUEST;
	bp->bp_htype = HWT_ETHER;
	bp->bp_hlen = HWL_ETHER;
	bp->bp_hops = 0;
	bp->bp_secs = htons(get_time_ns() >> 30);
	net_write_ip(&bp->bp_ciaddr, 0);
	net_write_ip(&bp->bp_yiaddr, 0);
	net_write_ip(&bp->bp_siaddr, 0);
	net_write_ip(&bp->bp_giaddr, 0);
	memcpy(bp->bp_chaddr, dhcp_con->et->et_src, 6);

	bfile = getenv("bootfile");
	if (bfile)
		safe_strncpy (bp->bp_file, bfile, sizeof(bp->bp_file));

	/* Request additional information from the BOOTP/DHCP server */
	ext_len = dhcp_extended((u8 *)bp->bp_vend, DHCP_DISCOVER, 0, 0);

	Bootp_id = (uint32_t)get_time_ns();
	net_copy_uint32(&bp->bp_id, &Bootp_id);

	dhcp_state = SELECTING;

	ret = net_udp_send(dhcp_con, sizeof(*bp) + ext_len);

	return ret;
}

static void dhcp_options_process(unsigned char *popt, struct bootp *bp)
{
	unsigned char *end = popt + sizeof(*bp) + OPT_SIZE;
	int oplen;
	IPaddr_t ip;
	char str[256];

	while (popt < end && *popt != 0xff) {
		oplen = *(popt + 1);
		switch (*popt) {
		case 1:
			ip = net_read_ip(popt + 2);
			net_set_netmask(ip);
			break;
		case 3:
			ip = net_read_ip(popt + 2);
			net_set_gateway(ip);
			break;
		case 6:
			ip = net_read_ip(popt + 2);
			setenv_ip("nameserver", ip);
			break;
		case 12:
			memcpy(str, popt + 2, oplen);
			str[oplen] = 0;
			setenv("hostname", str);
			break;
		case 15:
			memcpy(str, popt + 2, oplen);
			str[oplen] = 0;
			setenv("domainname", str);
			break;
		case 17:
			memcpy(str, popt + 2, oplen);
			str[oplen] = 0;
			setenv("rootpath", str);
			break;
		case 51:
			net_copy_uint32 (&dhcp_leasetime, (uint32_t *)(popt + 2));
			break;
		case 53:	/* Ignore Message Type Option */
			break;
		case 54:
			net_copy_ip(&net_dhcp_server_ip, (popt + 2));
			break;
		case 58:	/* Ignore Renewal Time Option */
			break;
		case 59:	/* Ignore Rebinding Time Option */
			break;
		case 66:	/* Ignore TFTP server name */
			break;
		case 67:	/* vendor opt bootfile */
			/*
			 * I can't use dhcp_vendorex_proc here because I need
			 * to write into the bootp packet - even then I had to
			 * pass the bootp packet pointer into here as the
			 * second arg
			 */
			memcpy(str, popt + 2, oplen);
			str[oplen] = 0;
			if (bp->bp_file[0] == '\0') {
				/*
				 * only use vendor boot file if we didn't
				 * receive a boot file in the main non-vendor
				 * part of the packet - god only knows why
				 * some vendors chose not to use this perfectly
				 * good spot to store the boot file (join on
				 * Tru64 Unix) it seems mind bogglingly crazy
				 * to me
				 */
				printf("*** WARNING: using vendor "
					"optional boot file\n");
					setenv("bootfile", str);
			}
			break;
		default:
#ifdef CONFIG_BOOTP_VENDOREX
			if (dhcp_vendorex_proc (popt))
				break;
#endif
			debug("*** Unhandled DHCP Option in OFFER/ACK: %d\n", *popt);
			break;
		}
		popt += oplen + 2;	/* Process next option */
	}
}

static int dhcp_message_type(unsigned char *popt)
{
	if (net_read_uint32((uint32_t *)popt) != htonl(BOOTP_VENDOR_MAGIC))
		return -1;

	popt += 4;
	while ( *popt != 0xff ) {
		if ( *popt == 53 )	/* DHCP Message Type */
			return *(popt + 2);
		popt += *(popt + 1) + 2;	/* Scan through all options */
	}
	return -1;
}

static void dhcp_send_request_packet(struct bootp *bp_offer)
{
	struct bootp *bp;
	int extlen;
	IPaddr_t OfferedIP;
	unsigned char *payload = net_udp_get_payload(dhcp_con);

	debug("%s: Sending DHCPREQUEST\n", __func__);

	bp = (struct bootp *)payload;
	bp->bp_op = OP_BOOTREQUEST;
	bp->bp_htype = HWT_ETHER;
	bp->bp_hlen = HWL_ETHER;
	bp->bp_hops = 0;
	/* FIXME what is this? */
//	bp->bp_secs = htons(get_timer(0) / CFG_HZ);
	net_copy_ip(&bp->bp_ciaddr, &bp_offer->bp_ciaddr); /* both in network byte order */
	net_copy_ip(&bp->bp_yiaddr, &bp_offer->bp_yiaddr);
	net_copy_ip(&bp->bp_siaddr, &bp_offer->bp_siaddr);
	/*
	 * RFC3046 requires Relay Agents to discard packets with
	 * nonzero and offered giaddr
	 */
	net_write_ip(&bp->bp_giaddr, 0);

	memcpy(bp->bp_chaddr, dhcp_con->et->et_src, 6);

	/*
	 * ID is the id of the OFFER packet
	 */

	net_copy_uint32(&bp->bp_id, &bp_offer->bp_id);

	/*
	 * Copy options from OFFER packet if present
	 */
	net_copy_ip(&OfferedIP, &bp->bp_yiaddr);
	extlen = dhcp_extended((u8 *)bp->bp_vend, DHCP_REQUEST, net_dhcp_server_ip, OfferedIP);

	debug("Transmitting DHCPREQUEST packet\n");
	net_udp_send(dhcp_con, sizeof(*bp) + extlen);
}

/*
 *	Handle DHCP received packets.
 */
static void dhcp_handler(void *ctx, char *packet, unsigned int len)
{
	char *pkt = net_eth_to_udp_payload(packet);
	struct udphdr *udp = net_eth_to_udphdr(packet);
	struct bootp *bp = (struct bootp *)pkt;

	len = net_eth_to_udplen(packet);

	debug("DHCPHandler: got packet: (len=%d) state: %d\n",
		len, dhcp_state);

	if (bootp_check_packet(pkt, ntohs(udp->uh_sport), len)) /* Filter out pkts we don't want */
		return;

	switch (dhcp_state) {
	case SELECTING:
		/*
		 * Wait an appropriate time for any potential DHCPOFFER packets
		 * to arrive.  Then select one, and generate DHCPREQUEST response.
		 * If filename is in format we recognize, assume it is a valid
		 * OFFER from a server we want.
		 */
		debug ("%s: state SELECTING, bp_file: \"%s\"\n", __func__, bp->bp_file);
		dhcp_state = REQUESTING;

		if (net_read_uint32((uint32_t *)&bp->bp_vend[0]) == htonl(BOOTP_VENDOR_MAGIC))
			dhcp_options_process((u8 *)&bp->bp_vend[4], bp);

		bootp_copy_net_params(bp); /* Store net params from reply */

		dhcp_start = get_time_ns();
		dhcp_send_request_packet(bp);

		break;
	case REQUESTING:
		debug ("%s: State REQUESTING\n", __func__);

		if (dhcp_message_type((u8 *)bp->bp_vend) == DHCP_ACK ) {
			if (net_read_uint32((uint32_t *)&bp->bp_vend[0]) == htonl(BOOTP_VENDOR_MAGIC))
				dhcp_options_process((u8 *)&bp->bp_vend[4], bp);
			bootp_copy_net_params(bp); /* Store net params from reply */
			dhcp_state = BOUND;
			puts ("DHCP client bound to address ");
			print_IPaddr(net_get_ip());
			putchar('\n');
			return;
		}
		break;
	default:
		debug("%s: INVALID STATE\n", __func__);
		break;
	}
}

static int do_dhcp(int argc, char *argv[])
{
	int ret;

	dhcp_con = net_udp_new(0xffffffff, PORT_BOOTPS, dhcp_handler, NULL);
	if (IS_ERR(dhcp_con)) {
		ret = PTR_ERR(dhcp_con);
		goto out;
	}

	ret = net_udp_bind(dhcp_con, PORT_BOOTPC);
	if (ret)
		goto out1;

	net_set_ip(0);

	ret = bootp_request(); /* Basically same as BOOTP */
	if (ret)
		goto out1;

	while (dhcp_state != BOUND) {
		if (ctrlc())
			break;
		net_poll();
		if (is_timeout(dhcp_start, 3 * SECOND)) {
			dhcp_start = get_time_ns();
			printf("T ");
			ret = bootp_request();
			if (ret)
				goto out1;
		}
	}

out1:
	net_unregister(dhcp_con);
out:
	if (ret)
		printf("dhcp failed: %s\n", strerror(-ret));

	return ret ? 1 : 0;
}

BAREBOX_CMD_START(dhcp)
	.cmd		= do_dhcp,
	.usage		= "invoke dhcp client to obtain ip/boot params",
BAREBOX_CMD_END

BAREBOX_MAGICVAR(bootfile, "bootfile returned from DHCP request");
BAREBOX_MAGICVAR(nameserver, "Nameserver returned from DHCP request");
BAREBOX_MAGICVAR(hostname, "hostname returned from DHCP request");
BAREBOX_MAGICVAR(domainname, "domainname returned from DHCP request");
BAREBOX_MAGICVAR(rootpath, "rootpath returned from DHCP request");