• Home
  • Line#
  • Scopes#
  • Navigate#
  • Raw
  • Download
1 /*
2  * Copyright (C) 2006 Michael Brown <mbrown@fensystems.co.uk>.
3  *
4  * This program is free software; you can redistribute it and/or
5  * modify it under the terms of the GNU General Public License as
6  * published by the Free Software Foundation; either version 2 of the
7  * License, or any later version.
8  *
9  * This program is distributed in the hope that it will be useful, but
10  * WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12  * General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
17  */
18 
19 FILE_LICENCE ( GPL2_OR_LATER );
20 
21 #include <string.h>
22 #include <stdlib.h>
23 #include <stdio.h>
24 #include <ctype.h>
25 #include <errno.h>
26 #include <assert.h>
27 #include <byteswap.h>
28 #include <gpxe/if_ether.h>
29 #include <gpxe/netdevice.h>
30 #include <gpxe/device.h>
31 #include <gpxe/xfer.h>
32 #include <gpxe/open.h>
33 #include <gpxe/job.h>
34 #include <gpxe/retry.h>
35 #include <gpxe/tcpip.h>
36 #include <gpxe/ip.h>
37 #include <gpxe/uuid.h>
38 #include <gpxe/timer.h>
39 #include <gpxe/settings.h>
40 #include <gpxe/dhcp.h>
41 #include <gpxe/dhcpopts.h>
42 #include <gpxe/dhcppkt.h>
43 #include <gpxe/features.h>
44 
45 /** @file
46  *
47  * Dynamic Host Configuration Protocol
48  *
49  */
50 
51 struct dhcp_session;
52 static int dhcp_tx ( struct dhcp_session *dhcp );
53 
54 /**
55  * DHCP operation types
56  *
57  * This table maps from DHCP message types (i.e. values of the @c
58  * DHCP_MESSAGE_TYPE option) to values of the "op" field within a DHCP
59  * packet.
60  */
61 static const uint8_t dhcp_op[] = {
62 	[DHCPDISCOVER]	= BOOTP_REQUEST,
63 	[DHCPOFFER]	= BOOTP_REPLY,
64 	[DHCPREQUEST]	= BOOTP_REQUEST,
65 	[DHCPDECLINE]	= BOOTP_REQUEST,
66 	[DHCPACK]	= BOOTP_REPLY,
67 	[DHCPNAK]	= BOOTP_REPLY,
68 	[DHCPRELEASE]	= BOOTP_REQUEST,
69 	[DHCPINFORM]	= BOOTP_REQUEST,
70 };
71 
72 /** Raw option data for options common to all DHCP requests */
73 static uint8_t dhcp_request_options_data[] = {
74 	DHCP_MESSAGE_TYPE, DHCP_BYTE ( 0 ),
75 	DHCP_MAX_MESSAGE_SIZE,
76 	DHCP_WORD ( ETH_MAX_MTU - 20 /* IP header */ - 8 /* UDP header */ ),
77 	DHCP_CLIENT_ARCHITECTURE, DHCP_WORD ( 0 ),
78 	DHCP_CLIENT_NDI, DHCP_OPTION ( 1 /* UNDI */ , 2, 1 /* v2.1 */ ),
79 	DHCP_VENDOR_CLASS_ID,
80 	DHCP_STRING (  'P', 'X', 'E', 'C', 'l', 'i', 'e', 'n', 't', ':',
81 		       'A', 'r', 'c', 'h', ':', '0', '0', '0', '0', '0', ':',
82 		       'U', 'N', 'D', 'I', ':', '0', '0', '2', '0', '0', '1' ),
83 	DHCP_USER_CLASS_ID,
84 	DHCP_STRING ( 'g', 'P', 'X', 'E' ),
85 	DHCP_PARAMETER_REQUEST_LIST,
86 	DHCP_OPTION ( DHCP_SUBNET_MASK, DHCP_ROUTERS, DHCP_DNS_SERVERS,
87 		      DHCP_LOG_SERVERS, DHCP_HOST_NAME, DHCP_DOMAIN_NAME,
88 		      DHCP_ROOT_PATH, DHCP_VENDOR_ENCAP, DHCP_VENDOR_CLASS_ID,
89 		      DHCP_TFTP_SERVER_NAME, DHCP_BOOTFILE_NAME,
90 		      DHCP_EB_ENCAP, DHCP_ISCSI_INITIATOR_IQN ),
91 	DHCP_END
92 };
93 
94 /** Version number feature */
95 FEATURE_VERSION ( VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH );
96 
97 /** DHCP server address setting */
98 struct setting dhcp_server_setting __setting = {
99 	.name = "dhcp-server",
100 	.description = "DHCP server address",
101 	.tag = DHCP_SERVER_IDENTIFIER,
102 	.type = &setting_type_ipv4,
103 };
104 
105 /** DHCP user class setting */
106 struct setting user_class_setting __setting = {
107 	.name = "user-class",
108 	.description = "User class identifier",
109 	.tag = DHCP_USER_CLASS_ID,
110 	.type = &setting_type_string,
111 };
112 
113 /** Use cached network settings */
114 struct setting use_cached_setting __setting = {
115 	.name = "use-cached",
116 	.description = "Use cached network settings",
117 	.tag = DHCP_EB_USE_CACHED,
118 	.type = &setting_type_uint8,
119 };
120 
121 /**
122  * Name a DHCP packet type
123  *
124  * @v msgtype		DHCP message type
125  * @ret string		DHCP mesasge type name
126  */
dhcp_msgtype_name(unsigned int msgtype)127 static inline const char * dhcp_msgtype_name ( unsigned int msgtype ) {
128 	switch ( msgtype ) {
129 	case DHCPNONE:		return "BOOTP"; /* Non-DHCP packet */
130 	case DHCPDISCOVER:	return "DHCPDISCOVER";
131 	case DHCPOFFER:		return "DHCPOFFER";
132 	case DHCPREQUEST:	return "DHCPREQUEST";
133 	case DHCPDECLINE:	return "DHCPDECLINE";
134 	case DHCPACK:		return "DHCPACK";
135 	case DHCPNAK:		return "DHCPNAK";
136 	case DHCPRELEASE:	return "DHCPRELEASE";
137 	case DHCPINFORM:	return "DHCPINFORM";
138 	default:		return "DHCP<invalid>";
139 	}
140 }
141 
142 /**
143  * Calculate DHCP transaction ID for a network device
144  *
145  * @v netdev		Network device
146  * @ret xid		DHCP XID
147  *
148  * Extract the least significant bits of the hardware address for use
149  * as the transaction ID.
150  */
dhcp_xid(struct net_device * netdev)151 static uint32_t dhcp_xid ( struct net_device *netdev ) {
152 	uint32_t xid;
153 
154 	memcpy ( &xid, ( netdev->ll_addr + netdev->ll_protocol->ll_addr_len
155 			 - sizeof ( xid ) ), sizeof ( xid ) );
156 	return xid;
157 }
158 
159 /****************************************************************************
160  *
161  * DHCP session
162  *
163  */
164 
165 struct dhcp_session;
166 
167 /** DHCP session state operations */
168 struct dhcp_session_state {
169 	/** State name */
170 	const char *name;
171 	/**
172 	 * Construct transmitted packet
173 	 *
174 	 * @v dhcp		DHCP session
175 	 * @v dhcppkt		DHCP packet
176 	 * @v peer		Destination address
177 	 */
178 	int ( * tx ) ( struct dhcp_session *dhcp,
179 		       struct dhcp_packet *dhcppkt,
180 		       struct sockaddr_in *peer );
181 	/** Handle received packet
182 	 *
183 	 * @v dhcp		DHCP session
184 	 * @v dhcppkt		DHCP packet
185 	 * @v peer		DHCP server address
186 	 * @v msgtype		DHCP message type
187 	 * @v server_id		DHCP server ID
188 	 */
189 	void ( * rx ) ( struct dhcp_session *dhcp,
190 			struct dhcp_packet *dhcppkt,
191 			struct sockaddr_in *peer,
192 			uint8_t msgtype, struct in_addr server_id );
193 	/** Handle timer expiry
194 	 *
195 	 * @v dhcp		DHCP session
196 	 */
197 	void ( * expired ) ( struct dhcp_session *dhcp );
198 	/** Transmitted message type */
199 	uint8_t tx_msgtype;
200 	/** Apply minimum timeout */
201 	uint8_t apply_min_timeout;
202 };
203 
204 static struct dhcp_session_state dhcp_state_discover;
205 static struct dhcp_session_state dhcp_state_request;
206 static struct dhcp_session_state dhcp_state_proxy;
207 static struct dhcp_session_state dhcp_state_pxebs;
208 
209 /** DHCP offer is valid for IP lease */
210 #define DHCP_OFFER_IP	1
211 
212 /** DHCP offer is valid for PXE options */
213 #define DHCP_OFFER_PXE	2
214 
215 /** A DHCP offer */
216 struct dhcp_offer {
217 	/** IP address of server granting offer */
218 	struct in_addr server;
219 
220 	/** IP address being offered, or 0.0.0.0 for a pure proxy */
221 	struct in_addr ip;
222 
223 	/** DHCP packet containing PXE options; NULL if missing or proxied */
224 	struct dhcp_packet *pxe;
225 
226 	/** Valid uses for this offer, a combination of DHCP_OFFER bits */
227 	uint8_t valid;
228 
229 	/** Priority of this offer */
230 	int8_t priority;
231 
232 	/** Whether to ignore PXE DHCP extensions */
233 	uint8_t no_pxedhcp;
234 };
235 
236 /** Maximum number of DHCP offers to queue */
237 #define DHCP_MAX_OFFERS   6
238 
239 /** A DHCP session */
240 struct dhcp_session {
241 	/** Reference counter */
242 	struct refcnt refcnt;
243 	/** Job control interface */
244 	struct job_interface job;
245 	/** Data transfer interface */
246 	struct xfer_interface xfer;
247 
248 	/** Network device being configured */
249 	struct net_device *netdev;
250 	/** Local socket address */
251 	struct sockaddr_in local;
252 	/** State of the session */
253 	struct dhcp_session_state *state;
254 
255 	/** PXE Boot Server type */
256 	uint16_t pxe_type;
257 	/** List of PXE Boot Servers to attempt */
258 	struct in_addr *pxe_attempt;
259 	/** List of PXE Boot Servers to accept */
260 	struct in_addr *pxe_accept;
261 
262 	/** Retransmission timer */
263 	struct retry_timer timer;
264 	/** Start time of the current state (in ticks) */
265 	unsigned long start;
266 
267 	/** DHCP offer just requested */
268 	struct dhcp_offer *current_offer;
269 	/** List of DHCP offers received */
270 	struct dhcp_offer offers[DHCP_MAX_OFFERS];
271 };
272 
273 /**
274  * Free DHCP session
275  *
276  * @v refcnt		Reference counter
277  */
dhcp_free(struct refcnt * refcnt)278 static void dhcp_free ( struct refcnt *refcnt ) {
279 	struct dhcp_session *dhcp =
280 		container_of ( refcnt, struct dhcp_session, refcnt );
281 	int i;
282 
283 	for ( i = 0 ; i < DHCP_MAX_OFFERS ; i++ ) {
284 		if ( dhcp->offers[i].pxe )
285 			dhcppkt_put ( dhcp->offers[i].pxe );
286 	}
287 
288 	netdev_put ( dhcp->netdev );
289 	free ( dhcp );
290 }
291 
292 /**
293  * Mark DHCP session as complete
294  *
295  * @v dhcp		DHCP session
296  * @v rc		Return status code
297  */
dhcp_finished(struct dhcp_session * dhcp,int rc)298 static void dhcp_finished ( struct dhcp_session *dhcp, int rc ) {
299 
300 	/* Block futher incoming messages */
301 	job_nullify ( &dhcp->job );
302 	xfer_nullify ( &dhcp->xfer );
303 
304 	/* Stop retry timer */
305 	stop_timer ( &dhcp->timer );
306 
307 	/* Free resources and close interfaces */
308 	xfer_close ( &dhcp->xfer, rc );
309 	job_done ( &dhcp->job, rc );
310 }
311 
312 /**
313  * Transition to new DHCP session state
314  *
315  * @v dhcp		DHCP session
316  * @v state		New session state
317  */
dhcp_set_state(struct dhcp_session * dhcp,struct dhcp_session_state * state)318 static void dhcp_set_state ( struct dhcp_session *dhcp,
319 			     struct dhcp_session_state *state ) {
320 
321 	DBGC ( dhcp, "DHCP %p entering %s state\n", dhcp, state->name );
322 	dhcp->state = state;
323 	dhcp->start = currticks();
324 	stop_timer ( &dhcp->timer );
325 	dhcp->timer.min_timeout =
326 		( state->apply_min_timeout ? DHCP_MIN_TIMEOUT : 0 );
327 	dhcp->timer.max_timeout = DHCP_MAX_TIMEOUT;
328 	start_timer_nodelay ( &dhcp->timer );
329 }
330 
331 /**
332  * Determine next DHCP offer to try
333  *
334  * @v dhcp		DHCP session
335  * @v type		DHCP offer type
336  * @ret offer		Next DHCP offer to try
337  *
338  * Offers are ranked by priority, then by completeness (combined
339  * IP+PXE are tried before @a type alone), then by order of receipt.
340  */
dhcp_next_offer(struct dhcp_session * dhcp,uint8_t type)341 static struct dhcp_offer * dhcp_next_offer ( struct dhcp_session *dhcp,
342 					     uint8_t type ) {
343 
344 	struct dhcp_offer *offer;
345 	struct dhcp_offer *best = NULL;
346 
347 	for ( offer = dhcp->offers ; offer < dhcp->offers + DHCP_MAX_OFFERS ;
348 	      offer++ ) {
349 		if ( ( offer->valid & type ) &&
350 		     ( ( best == NULL ) ||
351 		       ( offer->priority > best->priority ) ||
352 		       ( ( offer->priority == best->priority ) &&
353 			 ( offer->valid & ~best->valid ) ) ) )
354 			best = offer;
355 	}
356 
357 	return best;
358 }
359 
360 /****************************************************************************
361  *
362  * DHCP state machine
363  *
364  */
365 
366 /**
367  * Construct transmitted packet for DHCP discovery
368  *
369  * @v dhcp		DHCP session
370  * @v dhcppkt		DHCP packet
371  * @v peer		Destination address
372  */
dhcp_discovery_tx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt __unused,struct sockaddr_in * peer)373 static int dhcp_discovery_tx ( struct dhcp_session *dhcp,
374 			       struct dhcp_packet *dhcppkt __unused,
375 			       struct sockaddr_in *peer ) {
376 
377 	DBGC ( dhcp, "DHCP %p DHCPDISCOVER\n", dhcp );
378 
379 	/* Set server address */
380 	peer->sin_addr.s_addr = INADDR_BROADCAST;
381 	peer->sin_port = htons ( BOOTPS_PORT );
382 
383 	return 0;
384 }
385 
386 /**
387  * Handle received DHCPOFFER during any state
388  *
389  * @v dhcp		DHCP session
390  * @v dhcppkt		DHCP packet
391  * @v peer		DHCP server address
392  * @v msgtype		DHCP message type
393  * @v server_id		DHCP server ID
394  */
dhcp_rx_offer(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer,uint8_t msgtype,struct in_addr server_id)395 static void dhcp_rx_offer ( struct dhcp_session *dhcp,
396 			    struct dhcp_packet *dhcppkt,
397 			    struct sockaddr_in *peer, uint8_t msgtype,
398 			    struct in_addr server_id ) {
399 	char vci[9]; /* "PXEClient" */
400 	int vci_len;
401 	int has_pxeclient;
402 	int pxeopts_len;
403 	int has_pxeopts;
404 	struct dhcp_offer *offer;
405 	int i;
406 
407 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
408 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
409 	       ntohs ( peer->sin_port ) );
410 	if ( server_id.s_addr != peer->sin_addr.s_addr )
411 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
412 
413 	/* Identify offered IP address */
414 	if ( dhcppkt->dhcphdr->yiaddr.s_addr )
415 		DBGC ( dhcp, " for %s", inet_ntoa ( dhcppkt->dhcphdr->yiaddr ));
416 
417 	/* Enqueue an offer to be filled in */
418 	for ( i = 0 ; i < DHCP_MAX_OFFERS ; i++ ) {
419 		if ( dhcp->offers[i].server.s_addr == server_id.s_addr ) {
420 			DBGC ( dhcp, " dup\n" );
421 			return;
422 		}
423 
424 		if ( ! dhcp->offers[i].valid )
425 			break;
426 	}
427 	if ( i == DHCP_MAX_OFFERS ) {
428 		DBGC ( dhcp, " dropped\n" );
429 		return;
430 	}
431 
432 	offer = &dhcp->offers[i];
433 	offer->server = server_id;
434 	offer->ip = dhcppkt->dhcphdr->yiaddr;
435 
436 	/* Identify "PXEClient" vendor class */
437 	vci_len = dhcppkt_fetch ( dhcppkt, DHCP_VENDOR_CLASS_ID,
438 				  vci, sizeof ( vci ) );
439 	has_pxeclient = ( ( vci_len >= ( int ) sizeof ( vci ) ) &&
440 			  ( strncmp ( "PXEClient", vci, sizeof (vci) ) == 0 ));
441 
442 	/* Identify presence of PXE-specific options */
443 	pxeopts_len = dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU, NULL, 0 );
444 	has_pxeopts = ( pxeopts_len >= 0 );
445 	if ( has_pxeclient )
446 		DBGC ( dhcp, "%s", ( has_pxeopts ? " pxe" : " proxy" ) );
447 
448 	if ( has_pxeclient && has_pxeopts ) {
449 		/* Save reference to packet for future use */
450 		if ( offer->pxe )
451 			dhcppkt_put ( offer->pxe );
452 		offer->pxe = dhcppkt_get ( dhcppkt );
453 	}
454 
455 	/* Identify priority */
456 	dhcppkt_fetch ( dhcppkt, DHCP_EB_PRIORITY, &offer->priority,
457 			sizeof ( offer->priority ) );
458 	if ( offer->priority )
459 		DBGC ( dhcp, " pri %d", offer->priority );
460 
461 	/* Identify ignore-PXE flag */
462 	dhcppkt_fetch ( dhcppkt, DHCP_EB_NO_PXEDHCP, &offer->no_pxedhcp,
463 			sizeof ( offer->no_pxedhcp ) );
464 	if ( offer->no_pxedhcp )
465 		DBGC ( dhcp, " nopxe" );
466 	DBGC ( dhcp, "\n" );
467 
468 	/* Determine roles this offer can fill */
469 	if ( offer->ip.s_addr &&
470 	     ( peer->sin_port == htons ( BOOTPS_PORT ) ) &&
471 	     ( ( msgtype == DHCPOFFER ) || ( ! msgtype /* BOOTP */ ) ) )
472 		offer->valid |= DHCP_OFFER_IP;
473 
474 	if ( has_pxeclient && ( msgtype == DHCPOFFER ) )
475 		offer->valid |= DHCP_OFFER_PXE;
476 }
477 
478 /**
479  * Handle received packet during DHCP discovery
480  *
481  * @v dhcp		DHCP session
482  * @v dhcppkt		DHCP packet
483  * @v peer		DHCP server address
484  * @v msgtype		DHCP message type
485  * @v server_id		DHCP server ID
486  */
dhcp_discovery_rx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer,uint8_t msgtype,struct in_addr server_id)487 static void dhcp_discovery_rx ( struct dhcp_session *dhcp,
488 				struct dhcp_packet *dhcppkt,
489 				struct sockaddr_in *peer, uint8_t msgtype,
490 				struct in_addr server_id ) {
491 	unsigned long elapsed;
492 	struct dhcp_offer *ip_offer;
493 
494 	dhcp_rx_offer ( dhcp, dhcppkt, peer, msgtype, server_id );
495 
496 	/* We can exit the discovery state when we have a valid
497 	 * DHCPOFFER, and either:
498 	 *
499 	 *  o  The DHCPOFFER instructs us to ignore ProxyDHCPOFFERs, or
500 	 *  o  We have a valid ProxyDHCPOFFER, or
501 	 *  o  We have allowed sufficient time for ProxyDHCPOFFERs.
502 	 */
503 
504 	/* If we don't yet have a DHCPOFFER, do nothing */
505 	ip_offer = dhcp_next_offer ( dhcp, DHCP_OFFER_IP );
506 	if ( ! ip_offer )
507 		return;
508 
509 	/* If we can't yet transition to DHCPREQUEST, do nothing */
510 	elapsed = ( currticks() - dhcp->start );
511 	if ( ! ( ip_offer->no_pxedhcp ||
512 		 dhcp_next_offer ( dhcp, DHCP_OFFER_PXE ) ||
513 		 ( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) )
514 		return;
515 
516 	/* Transition to DHCPREQUEST */
517 	dhcp_set_state ( dhcp, &dhcp_state_request );
518 }
519 
520 /**
521  * Handle timer expiry during DHCP discovery
522  *
523  * @v dhcp		DHCP session
524  */
dhcp_discovery_expired(struct dhcp_session * dhcp)525 static void dhcp_discovery_expired ( struct dhcp_session *dhcp ) {
526 	unsigned long elapsed = ( currticks() - dhcp->start );
527 
528 	/* Give up waiting for ProxyDHCP before we reach the failure point */
529 	if ( dhcp_next_offer ( dhcp, DHCP_OFFER_IP ) &&
530 	     ( elapsed > PROXYDHCP_MAX_TIMEOUT ) ) {
531 		dhcp_set_state ( dhcp, &dhcp_state_request );
532 		return;
533 	}
534 
535 	/* Otherwise, retransmit current packet */
536 	dhcp_tx ( dhcp );
537 }
538 
539 /** DHCP discovery state operations */
540 static struct dhcp_session_state dhcp_state_discover = {
541 	.name			= "discovery",
542 	.tx			= dhcp_discovery_tx,
543 	.rx			= dhcp_discovery_rx,
544 	.expired		= dhcp_discovery_expired,
545 	.tx_msgtype		= DHCPDISCOVER,
546 	.apply_min_timeout	= 1,
547 };
548 
549 /**
550  * Construct transmitted packet for DHCP request
551  *
552  * @v dhcp		DHCP session
553  * @v dhcppkt		DHCP packet
554  * @v peer		Destination address
555  */
dhcp_request_tx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer)556 static int dhcp_request_tx ( struct dhcp_session *dhcp,
557 			     struct dhcp_packet *dhcppkt,
558 			     struct sockaddr_in *peer ) {
559 	int rc;
560 	struct dhcp_offer *offer;
561 
562 	offer = dhcp->current_offer = dhcp_next_offer ( dhcp, DHCP_OFFER_IP );
563 
564 	DBGC ( dhcp, "DHCP %p DHCPREQUEST to %s:%d",
565 	       dhcp, inet_ntoa ( offer->server ), BOOTPS_PORT );
566 	DBGC ( dhcp, " for %s\n", inet_ntoa ( offer->ip ) );
567 
568 	/* Set server ID */
569 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_SERVER_IDENTIFIER,
570 				    &offer->server,
571 				    sizeof ( offer->server ) ) ) != 0 )
572 		return rc;
573 
574 	/* Set requested IP address */
575 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_REQUESTED_ADDRESS,
576 				    &offer->ip, sizeof ( offer->ip ) ) ) != 0 )
577 		return rc;
578 
579 	/* Set server address */
580 	peer->sin_addr.s_addr = INADDR_BROADCAST;
581 	peer->sin_port = htons ( BOOTPS_PORT );
582 
583 	return 0;
584 }
585 
586 /**
587  * Handle received packet during DHCP request
588  *
589  * @v dhcp		DHCP session
590  * @v dhcppkt		DHCP packet
591  * @v peer		DHCP server address
592  * @v msgtype		DHCP message type
593  * @v server_id		DHCP server ID
594  */
dhcp_request_rx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer,uint8_t msgtype,struct in_addr server_id)595 static void dhcp_request_rx ( struct dhcp_session *dhcp,
596 			      struct dhcp_packet *dhcppkt,
597 			      struct sockaddr_in *peer, uint8_t msgtype,
598 			      struct in_addr server_id ) {
599 	struct in_addr ip;
600 	struct settings *parent;
601 	int rc;
602 	struct dhcp_offer *pxe_offer;
603 
604 	if ( msgtype == DHCPOFFER ) {
605 		dhcp_rx_offer ( dhcp, dhcppkt, peer, msgtype, server_id );
606 		if ( dhcp_next_offer ( dhcp, DHCP_OFFER_IP ) !=
607 		     dhcp->current_offer ) {
608 			/* Restart due to higher-priority offer received */
609 			DBGC ( dhcp, "DHCP %p re-requesting\n", dhcp );
610 			dhcp_set_state ( dhcp, &dhcp_state_request );
611 		}
612 		return;
613 	}
614 
615 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
616 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
617 	       ntohs ( peer->sin_port ) );
618 	if ( server_id.s_addr != peer->sin_addr.s_addr )
619 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
620 
621 	/* Identify leased IP address */
622 	ip = dhcppkt->dhcphdr->yiaddr;
623 	if ( ip.s_addr )
624 		DBGC ( dhcp, " for %s", inet_ntoa ( ip ) );
625 	DBGC ( dhcp, "\n" );
626 
627 	/* Filter out unacceptable responses */
628 	if ( peer->sin_port != htons ( BOOTPS_PORT ) )
629 		return;
630 	if ( msgtype /* BOOTP */ && ( msgtype != DHCPACK ) )
631 		return;
632 	if ( server_id.s_addr != dhcp->current_offer->server.s_addr )
633 		return;
634 
635 	/* Record assigned address */
636 	dhcp->local.sin_addr = ip;
637 
638 	/* Register settings */
639 	parent = netdev_settings ( dhcp->netdev );
640 	if ( ( rc = register_settings ( &dhcppkt->settings, parent ) ) != 0 ){
641 		DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
642 		       dhcp, strerror ( rc ) );
643 		dhcp_finished ( dhcp, rc );
644 		return;
645 	}
646 
647 	/* Locate best source of PXE settings */
648 	pxe_offer = dhcp_next_offer ( dhcp, DHCP_OFFER_PXE );
649 
650 	if ( ( ! pxe_offer ) || /* No PXE available */
651 	     /* IP offer instructs us to ignore PXE */
652 	     dhcp->current_offer->no_pxedhcp ||
653 	     /* PXE settings already registered with IP offer */
654 	     ( ( dhcp->current_offer == pxe_offer ) && ( pxe_offer->pxe ) ) ) {
655 
656 		/* Terminate DHCP */
657 		dhcp_finished ( dhcp, 0 );
658 
659 	} else if ( pxe_offer->pxe ) {
660 		/* Register PXE settings and terminate DHCP */
661 		pxe_offer->pxe->settings.name = PROXYDHCP_SETTINGS_NAME;
662 		if ( ( rc = register_settings ( &pxe_offer->pxe->settings,
663 						NULL ) ) != 0 ) {
664 			DBGC ( dhcp, "DHCP %p could not register settings: "
665 			       "%s\n", dhcp, strerror ( rc ) );
666 		}
667 		dhcp_finished ( dhcp, rc );
668 	} else {
669 		/* Start ProxyDHCP */
670 		dhcp_set_state ( dhcp, &dhcp_state_proxy );
671 	}
672 }
673 
674 /**
675  * Handle timer expiry during DHCP discovery
676  *
677  * @v dhcp		DHCP session
678  */
dhcp_request_expired(struct dhcp_session * dhcp)679 static void dhcp_request_expired ( struct dhcp_session *dhcp ) {
680 
681 	/* Retransmit current packet */
682 	dhcp_tx ( dhcp );
683 }
684 
685 /** DHCP request state operations */
686 static struct dhcp_session_state dhcp_state_request = {
687 	.name			= "request",
688 	.tx			= dhcp_request_tx,
689 	.rx			= dhcp_request_rx,
690 	.expired		= dhcp_request_expired,
691 	.tx_msgtype		= DHCPREQUEST,
692 	.apply_min_timeout	= 0,
693 };
694 
695 /**
696  * Construct transmitted packet for ProxyDHCP request
697  *
698  * @v dhcp		DHCP session
699  * @v dhcppkt		DHCP packet
700  * @v peer		Destination address
701  */
dhcp_proxy_tx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer)702 static int dhcp_proxy_tx ( struct dhcp_session *dhcp,
703 			   struct dhcp_packet *dhcppkt,
704 			   struct sockaddr_in *peer ) {
705 	int rc;
706 	struct dhcp_offer *offer;
707 
708 	offer = dhcp->current_offer = dhcp_next_offer ( dhcp, DHCP_OFFER_PXE );
709 
710 	DBGC ( dhcp, "DHCP %p ProxyDHCP REQUEST to %s:%d\n", dhcp,
711 	       inet_ntoa ( offer->server ), PXE_PORT );
712 
713 	/* Set server ID */
714 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_SERVER_IDENTIFIER,
715 				    &offer->server,
716 				    sizeof ( offer->server ) ) )  != 0 )
717 		return rc;
718 
719 	/* Set server address */
720 	peer->sin_addr = offer->server;
721 	peer->sin_port = htons ( PXE_PORT );
722 
723 	return 0;
724 }
725 
726 /**
727  * Handle received packet during ProxyDHCP request
728  *
729  * @v dhcp		DHCP session
730  * @v dhcppkt		DHCP packet
731  * @v peer		DHCP server address
732  * @v msgtype		DHCP message type
733  * @v server_id		DHCP server ID
734  */
dhcp_proxy_rx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer,uint8_t msgtype,struct in_addr server_id)735 static void dhcp_proxy_rx ( struct dhcp_session *dhcp,
736 			    struct dhcp_packet *dhcppkt,
737 			    struct sockaddr_in *peer, uint8_t msgtype,
738 			    struct in_addr server_id ) {
739 	int rc;
740 
741 	/* Enqueue last-minute DHCPOFFERs for use in case of failure */
742 	if ( peer->sin_port == htons ( BOOTPS_PORT ) &&
743 	     msgtype == DHCPOFFER ) {
744 		dhcp_rx_offer ( dhcp, dhcppkt, peer, msgtype, server_id );
745 		return;
746 	}
747 
748 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
749 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
750 	       ntohs ( peer->sin_port ) );
751 	if ( server_id.s_addr != peer->sin_addr.s_addr )
752 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
753 	DBGC ( dhcp, "\n" );
754 
755 	/* Filter out unacceptable responses */
756 	if ( peer->sin_port != htons ( PXE_PORT ) )
757 		return;
758 	if ( msgtype != DHCPACK && msgtype != DHCPOFFER )
759 		return;
760 	if ( server_id.s_addr /* Linux PXE server omits server ID */ &&
761 	     ( server_id.s_addr != dhcp->current_offer->server.s_addr ) )
762 		return;
763 
764 	/* Register settings */
765 	dhcppkt->settings.name = PROXYDHCP_SETTINGS_NAME;
766 	if ( ( rc = register_settings ( &dhcppkt->settings, NULL ) ) != 0 ) {
767 		DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
768 		       dhcp, strerror ( rc ) );
769 		dhcp_finished ( dhcp, rc );
770 		return;
771 	}
772 
773 	/* Terminate DHCP */
774 	dhcp_finished ( dhcp, 0 );
775 }
776 
777 /**
778  * Handle timer expiry during ProxyDHCP request
779  *
780  * @v dhcp		DHCP session
781  */
dhcp_proxy_expired(struct dhcp_session * dhcp)782 static void dhcp_proxy_expired ( struct dhcp_session *dhcp ) {
783 	unsigned long elapsed = ( currticks() - dhcp->start );
784 
785 	/* Give up waiting for ProxyDHCP before we reach the failure point */
786 	if ( elapsed > PROXYDHCP_MAX_TIMEOUT ) {
787 
788 		/* Mark failed offer as unsuitable for ProxyDHCP */
789 		dhcp->current_offer->valid &= ~DHCP_OFFER_PXE;
790 
791 		/* Prefer not to use only half of a PXE+IP offer if we
792 		 * have other offers available
793 		 */
794 		dhcp->current_offer->priority = -1;
795 
796 		/* If we have any other PXE offers we can try, go back
797 		 * to DHCPREQUEST (since they might not be proxied
798 		 * offers, or might be coupled to a new IP address).
799 		 * We should probably DHCPRELEASE our old IP, but the
800 		 * standard does not require it.
801 		 */
802 		if ( dhcp_next_offer ( dhcp, DHCP_OFFER_PXE ) ) {
803 			dhcp->local.sin_addr.s_addr = 0;
804 			dhcp_set_state ( dhcp, &dhcp_state_request );
805 			return;
806 		}
807 
808 		/* No possibilities left; finish without PXE options */
809 		dhcp_finished ( dhcp, 0 );
810 		return;
811 	}
812 
813 	/* Retransmit current packet */
814 	dhcp_tx ( dhcp );
815 }
816 
817 /** ProxyDHCP request state operations */
818 static struct dhcp_session_state dhcp_state_proxy = {
819 	.name			= "ProxyDHCP",
820 	.tx			= dhcp_proxy_tx,
821 	.rx			= dhcp_proxy_rx,
822 	.expired		= dhcp_proxy_expired,
823 	.tx_msgtype		= DHCPREQUEST,
824 	.apply_min_timeout	= 0,
825 };
826 
827 /**
828  * Construct transmitted packet for PXE Boot Server Discovery
829  *
830  * @v dhcp		DHCP session
831  * @v dhcppkt		DHCP packet
832  * @v peer		Destination address
833  */
dhcp_pxebs_tx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer)834 static int dhcp_pxebs_tx ( struct dhcp_session *dhcp,
835 			   struct dhcp_packet *dhcppkt,
836 			   struct sockaddr_in *peer ) {
837 	struct dhcp_pxe_boot_menu_item menu_item = { 0, 0 };
838 	int rc;
839 
840 	/* Set server address */
841 	peer->sin_addr = *(dhcp->pxe_attempt);
842 	peer->sin_port = ( ( peer->sin_addr.s_addr == INADDR_BROADCAST ) ?
843 			   htons ( BOOTPS_PORT ) : htons ( PXE_PORT ) );
844 
845 	DBGC ( dhcp, "DHCP %p PXEBS REQUEST to %s:%d for type %d\n",
846 	       dhcp, inet_ntoa ( peer->sin_addr ), ntohs ( peer->sin_port ),
847 	       le16_to_cpu ( dhcp->pxe_type ) );
848 
849 	/* Set boot menu item */
850 	menu_item.type = dhcp->pxe_type;
851 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_PXE_BOOT_MENU_ITEM,
852 				    &menu_item, sizeof ( menu_item ) ) ) != 0 )
853 		return rc;
854 
855 	return 0;
856 }
857 
858 /**
859  * Check to see if PXE Boot Server address is acceptable
860  *
861  * @v dhcp		DHCP session
862  * @v bs		Boot Server address
863  * @ret accept		Boot Server is acceptable
864  */
dhcp_pxebs_accept(struct dhcp_session * dhcp,struct in_addr bs)865 static int dhcp_pxebs_accept ( struct dhcp_session *dhcp,
866 			       struct in_addr bs ) {
867 	struct in_addr *accept;
868 
869 	/* Accept if we have no acceptance filter */
870 	if ( ! dhcp->pxe_accept )
871 		return 1;
872 
873 	/* Scan through acceptance list */
874 	for ( accept = dhcp->pxe_accept ; accept->s_addr ; accept++ ) {
875 		if ( accept->s_addr == bs.s_addr )
876 			return 1;
877 	}
878 
879 	DBGC ( dhcp, "DHCP %p rejecting server %s\n",
880 	       dhcp, inet_ntoa ( bs ) );
881 	return 0;
882 }
883 
884 /**
885  * Handle received packet during PXE Boot Server Discovery
886  *
887  * @v dhcp		DHCP session
888  * @v dhcppkt		DHCP packet
889  * @v peer		DHCP server address
890  * @v msgtype		DHCP message type
891  * @v server_id		DHCP server ID
892  */
dhcp_pxebs_rx(struct dhcp_session * dhcp,struct dhcp_packet * dhcppkt,struct sockaddr_in * peer,uint8_t msgtype,struct in_addr server_id)893 static void dhcp_pxebs_rx ( struct dhcp_session *dhcp,
894 			    struct dhcp_packet *dhcppkt,
895 			    struct sockaddr_in *peer, uint8_t msgtype,
896 			    struct in_addr server_id ) {
897 	struct dhcp_pxe_boot_menu_item menu_item = { 0, 0 };
898 	int rc;
899 
900 	DBGC ( dhcp, "DHCP %p %s from %s:%d", dhcp,
901 	       dhcp_msgtype_name ( msgtype ), inet_ntoa ( peer->sin_addr ),
902 	       ntohs ( peer->sin_port ) );
903 	if ( server_id.s_addr != peer->sin_addr.s_addr )
904 		DBGC ( dhcp, " (%s)", inet_ntoa ( server_id ) );
905 
906 	/* Identify boot menu item */
907 	dhcppkt_fetch ( dhcppkt, DHCP_PXE_BOOT_MENU_ITEM,
908 			&menu_item, sizeof ( menu_item ) );
909 	if ( menu_item.type )
910 		DBGC ( dhcp, " for type %d", ntohs ( menu_item.type ) );
911 	DBGC ( dhcp, "\n" );
912 
913 	/* Filter out unacceptable responses */
914 	if ( ( peer->sin_port != htons ( BOOTPS_PORT ) ) &&
915 	     ( peer->sin_port != htons ( PXE_PORT ) ) )
916 		return;
917 	if ( msgtype != DHCPACK )
918 		return;
919 	if ( menu_item.type != dhcp->pxe_type )
920 		return;
921 	if ( ! dhcp_pxebs_accept ( dhcp, ( server_id.s_addr ?
922 					   server_id : peer->sin_addr ) ) )
923 		return;
924 
925 	/* Register settings */
926 	dhcppkt->settings.name = PXEBS_SETTINGS_NAME;
927 	if ( ( rc = register_settings ( &dhcppkt->settings, NULL ) ) != 0 ) {
928 		DBGC ( dhcp, "DHCP %p could not register settings: %s\n",
929 		       dhcp, strerror ( rc ) );
930 		dhcp_finished ( dhcp, rc );
931 		return;
932 	}
933 
934 	/* Terminate DHCP */
935 	dhcp_finished ( dhcp, 0 );
936 }
937 
938 /**
939  * Handle timer expiry during PXE Boot Server Discovery
940  *
941  * @v dhcp		DHCP session
942  */
dhcp_pxebs_expired(struct dhcp_session * dhcp)943 static void dhcp_pxebs_expired ( struct dhcp_session *dhcp ) {
944 	unsigned long elapsed = ( currticks() - dhcp->start );
945 
946 	/* Give up waiting before we reach the failure point, and fail
947 	 * over to the next server in the attempt list
948 	 */
949 	if ( elapsed > PXEBS_MAX_TIMEOUT ) {
950 		dhcp->pxe_attempt++;
951 		if ( dhcp->pxe_attempt->s_addr ) {
952 			dhcp_set_state ( dhcp, &dhcp_state_pxebs );
953 			return;
954 		} else {
955 			dhcp_finished ( dhcp, -ETIMEDOUT );
956 			return;
957 		}
958 	}
959 
960 	/* Retransmit current packet */
961 	dhcp_tx ( dhcp );
962 }
963 
964 /** PXE Boot Server Discovery state operations */
965 static struct dhcp_session_state dhcp_state_pxebs = {
966 	.name			= "PXEBS",
967 	.tx			= dhcp_pxebs_tx,
968 	.rx			= dhcp_pxebs_rx,
969 	.expired		= dhcp_pxebs_expired,
970 	.tx_msgtype		= DHCPREQUEST,
971 	.apply_min_timeout	= 1,
972 };
973 
974 /****************************************************************************
975  *
976  * Packet construction
977  *
978  */
979 
980 /**
981  * Construct DHCP client hardware address field and broadcast flag
982  *
983  * @v netdev		Network device
984  * @v hlen		DHCP hardware address length to fill in
985  * @v flags		DHCP flags to fill in
986  * @ret chaddr		DHCP client hardware address
987  */
dhcp_chaddr(struct net_device * netdev,uint8_t * hlen,uint16_t * flags)988 void * dhcp_chaddr ( struct net_device *netdev, uint8_t *hlen,
989 		     uint16_t *flags ) {
990 	struct ll_protocol *ll_protocol = netdev->ll_protocol;
991 	typeof ( ( ( struct dhcphdr * ) NULL )->chaddr ) chaddr;
992 
993 	/* If the link-layer address cannot fit into the chaddr field
994 	 * (as is the case for IPoIB) then try using the hardware
995 	 * address instead.  If we do this, set the broadcast flag,
996 	 * since chaddr then does not represent a valid link-layer
997 	 * address for the return path.
998 	 *
999 	 * If even the hardware address is too large, use an empty
1000 	 * chaddr field and set the broadcast flag.
1001 	 *
1002 	 * This goes against RFC4390, but RFC4390 mandates that we use
1003 	 * a DHCP client identifier that conforms with RFC4361, which
1004 	 * we cannot do without either persistent (NIC-independent)
1005 	 * storage, or by eliminating the hardware address completely
1006 	 * from the DHCP packet, which seems unfriendly to users.
1007 	 */
1008 	if ( ( *hlen = ll_protocol->ll_addr_len ) <= sizeof ( chaddr ) ) {
1009 		return netdev->ll_addr;
1010 	}
1011 	*flags = htons ( BOOTP_FL_BROADCAST );
1012 	if ( ( *hlen = ll_protocol->hw_addr_len ) <= sizeof ( chaddr ) ) {
1013 		return netdev->hw_addr;
1014 	} else {
1015 		*hlen = 0;
1016 		return NULL;
1017 	}
1018 }
1019 
1020 /**
1021  * Create a DHCP packet
1022  *
1023  * @v dhcppkt		DHCP packet structure to fill in
1024  * @v netdev		Network device
1025  * @v msgtype		DHCP message type
1026  * @v options		Initial options to include (or NULL)
1027  * @v options_len	Length of initial options
1028  * @v data		Buffer for DHCP packet
1029  * @v max_len		Size of DHCP packet buffer
1030  * @ret rc		Return status code
1031  *
1032  * Creates a DHCP packet in the specified buffer, and initialise a
1033  * DHCP packet structure.
1034  */
dhcp_create_packet(struct dhcp_packet * dhcppkt,struct net_device * netdev,uint8_t msgtype,const void * options,size_t options_len,void * data,size_t max_len)1035 int dhcp_create_packet ( struct dhcp_packet *dhcppkt,
1036 			 struct net_device *netdev, uint8_t msgtype,
1037 			 const void *options, size_t options_len,
1038 			 void *data, size_t max_len ) {
1039 	struct dhcphdr *dhcphdr = data;
1040 	void *chaddr;
1041 	int rc;
1042 
1043 	/* Sanity check */
1044 	if ( max_len < ( sizeof ( *dhcphdr ) + options_len ) )
1045 		return -ENOSPC;
1046 
1047 	/* Initialise DHCP packet content */
1048 	memset ( dhcphdr, 0, max_len );
1049 	dhcphdr->xid = dhcp_xid ( netdev );
1050 	dhcphdr->magic = htonl ( DHCP_MAGIC_COOKIE );
1051 	dhcphdr->htype = ntohs ( netdev->ll_protocol->ll_proto );
1052 	dhcphdr->op = dhcp_op[msgtype];
1053 	chaddr = dhcp_chaddr ( netdev, &dhcphdr->hlen, &dhcphdr->flags );
1054 	memcpy ( dhcphdr->chaddr, chaddr, dhcphdr->hlen );
1055 	memcpy ( dhcphdr->options, options, options_len );
1056 
1057 	/* Initialise DHCP packet structure */
1058 	memset ( dhcppkt, 0, sizeof ( *dhcppkt ) );
1059 	dhcppkt_init ( dhcppkt, data, max_len );
1060 
1061 	/* Set DHCP_MESSAGE_TYPE option */
1062 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_MESSAGE_TYPE,
1063 				    &msgtype, sizeof ( msgtype ) ) ) != 0 )
1064 		return rc;
1065 
1066 	return 0;
1067 }
1068 
1069 /**
1070  * Create DHCP request packet
1071  *
1072  * @v dhcppkt		DHCP packet structure to fill in
1073  * @v netdev		Network device
1074  * @v msgtype		DHCP message type
1075  * @v ciaddr		Client IP address
1076  * @v data		Buffer for DHCP packet
1077  * @v max_len		Size of DHCP packet buffer
1078  * @ret rc		Return status code
1079  *
1080  * Creates a DHCP request packet in the specified buffer, and
1081  * initialise a DHCP packet structure.
1082  */
dhcp_create_request(struct dhcp_packet * dhcppkt,struct net_device * netdev,unsigned int msgtype,struct in_addr ciaddr,void * data,size_t max_len)1083 int dhcp_create_request ( struct dhcp_packet *dhcppkt,
1084 			  struct net_device *netdev, unsigned int msgtype,
1085 			  struct in_addr ciaddr, void *data, size_t max_len ) {
1086 	struct dhcp_netdev_desc dhcp_desc;
1087 	struct dhcp_client_id client_id;
1088 	struct dhcp_client_uuid client_uuid;
1089 	uint8_t *dhcp_features;
1090 	size_t dhcp_features_len;
1091 	size_t ll_addr_len;
1092 	ssize_t len;
1093 	int rc;
1094 
1095 	/* Create DHCP packet */
1096 	if ( ( rc = dhcp_create_packet ( dhcppkt, netdev, msgtype,
1097 					 dhcp_request_options_data,
1098 					 sizeof ( dhcp_request_options_data ),
1099 					 data, max_len ) ) != 0 ) {
1100 		DBG ( "DHCP could not create DHCP packet: %s\n",
1101 		      strerror ( rc ) );
1102 		return rc;
1103 	}
1104 
1105 	/* Set client IP address */
1106 	dhcppkt->dhcphdr->ciaddr = ciaddr;
1107 
1108 	/* Add options to identify the feature list */
1109 	dhcp_features = table_start ( DHCP_FEATURES );
1110 	dhcp_features_len = table_num_entries ( DHCP_FEATURES );
1111 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_EB_ENCAP, dhcp_features,
1112 				    dhcp_features_len ) ) != 0 ) {
1113 		DBG ( "DHCP could not set features list option: %s\n",
1114 		      strerror ( rc ) );
1115 		return rc;
1116 	}
1117 
1118 	/* Add options to identify the network device */
1119 	fetch_setting ( &netdev->settings.settings, &busid_setting, &dhcp_desc,
1120 		sizeof ( dhcp_desc ) );
1121 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_EB_BUS_ID, &dhcp_desc,
1122 				    sizeof ( dhcp_desc ) ) ) != 0 ) {
1123 		DBG ( "DHCP could not set bus ID option: %s\n",
1124 		      strerror ( rc ) );
1125 		return rc;
1126 	}
1127 
1128 	/* Add DHCP client identifier.  Required for Infiniband, and
1129 	 * doesn't hurt other link layers.
1130 	 */
1131 	client_id.ll_proto = ntohs ( netdev->ll_protocol->ll_proto );
1132 	ll_addr_len = netdev->ll_protocol->ll_addr_len;
1133 	assert ( ll_addr_len <= sizeof ( client_id.ll_addr ) );
1134 	memcpy ( client_id.ll_addr, netdev->ll_addr, ll_addr_len );
1135 	if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_CLIENT_ID, &client_id,
1136 				    ( ll_addr_len + 1 ) ) ) != 0 ) {
1137 		DBG ( "DHCP could not set client ID: %s\n",
1138 		      strerror ( rc ) );
1139 		return rc;
1140 	}
1141 
1142 	/* Add client UUID, if we have one.  Required for PXE. */
1143 	client_uuid.type = DHCP_CLIENT_UUID_TYPE;
1144 	if ( ( len = fetch_uuid_setting ( NULL, &uuid_setting,
1145 					  &client_uuid.uuid ) ) >= 0 ) {
1146 		if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_CLIENT_UUID,
1147 					    &client_uuid,
1148 					    sizeof ( client_uuid ) ) ) != 0 ) {
1149 			DBG ( "DHCP could not set client UUID: %s\n",
1150 			      strerror ( rc ) );
1151 			return rc;
1152 		}
1153 	}
1154 
1155 	/* Add user class, if we have one. */
1156 	if ( ( len = fetch_setting_len ( NULL, &user_class_setting ) ) >= 0 ) {
1157 		char user_class[len];
1158 		fetch_setting ( NULL, &user_class_setting, user_class,
1159 				sizeof ( user_class ) );
1160 		if ( ( rc = dhcppkt_store ( dhcppkt, DHCP_USER_CLASS_ID,
1161 					    &user_class,
1162 					    sizeof ( user_class ) ) ) != 0 ) {
1163 			DBG ( "DHCP could not set user class: %s\n",
1164 			      strerror ( rc ) );
1165 			return rc;
1166 		}
1167 	}
1168 
1169 	return 0;
1170 }
1171 
1172 /****************************************************************************
1173  *
1174  * Data transfer interface
1175  *
1176  */
1177 
1178 /**
1179  * Transmit DHCP request
1180  *
1181  * @v dhcp		DHCP session
1182  * @ret rc		Return status code
1183  */
dhcp_tx(struct dhcp_session * dhcp)1184 static int dhcp_tx ( struct dhcp_session *dhcp ) {
1185 	static struct sockaddr_in peer = {
1186 		.sin_family = AF_INET,
1187 	};
1188 	struct xfer_metadata meta = {
1189 		.netdev = dhcp->netdev,
1190 		.src = ( struct sockaddr * ) &dhcp->local,
1191 		.dest = ( struct sockaddr * ) &peer,
1192 	};
1193 	struct io_buffer *iobuf;
1194 	uint8_t msgtype = dhcp->state->tx_msgtype;
1195 	struct dhcp_packet dhcppkt;
1196 	int rc;
1197 
1198 	/* Start retry timer.  Do this first so that failures to
1199 	 * transmit will be retried.
1200 	 */
1201 	start_timer ( &dhcp->timer );
1202 
1203 	/* Allocate buffer for packet */
1204 	iobuf = xfer_alloc_iob ( &dhcp->xfer, DHCP_MIN_LEN );
1205 	if ( ! iobuf )
1206 		return -ENOMEM;
1207 
1208 	/* Create basic DHCP packet in temporary buffer */
1209 	if ( ( rc = dhcp_create_request ( &dhcppkt, dhcp->netdev, msgtype,
1210 					  dhcp->local.sin_addr, iobuf->data,
1211 					  iob_tailroom ( iobuf ) ) ) != 0 ) {
1212 		DBGC ( dhcp, "DHCP %p could not construct DHCP request: %s\n",
1213 		       dhcp, strerror ( rc ) );
1214 		goto done;
1215 	}
1216 
1217 	/* Fill in packet based on current state */
1218 	if ( ( rc = dhcp->state->tx ( dhcp, &dhcppkt, &peer ) ) != 0 ) {
1219 		DBGC ( dhcp, "DHCP %p could not fill DHCP request: %s\n",
1220 		       dhcp, strerror ( rc ) );
1221 		goto done;
1222 	}
1223 
1224 	/* Transmit the packet */
1225 	iob_put ( iobuf, dhcppkt.len );
1226 	if ( ( rc = xfer_deliver_iob_meta ( &dhcp->xfer, iob_disown ( iobuf ),
1227 					    &meta ) ) != 0 ) {
1228 		DBGC ( dhcp, "DHCP %p could not transmit UDP packet: %s\n",
1229 		       dhcp, strerror ( rc ) );
1230 		goto done;
1231 	}
1232 
1233  done:
1234 	free_iob ( iobuf );
1235 	return rc;
1236 }
1237 
1238 /**
1239  * Receive new data
1240  *
1241  * @v xfer 		Data transfer interface
1242  * @v iobuf		I/O buffer
1243  * @v meta		Transfer metadata
1244  * @ret rc		Return status code
1245  */
dhcp_deliver_iob(struct xfer_interface * xfer,struct io_buffer * iobuf,struct xfer_metadata * meta)1246 static int dhcp_deliver_iob ( struct xfer_interface *xfer,
1247 			      struct io_buffer *iobuf,
1248 			      struct xfer_metadata *meta ) {
1249 	struct dhcp_session *dhcp =
1250 		container_of ( xfer, struct dhcp_session, xfer );
1251 	struct sockaddr_in *peer;
1252 	size_t data_len;
1253 	struct dhcp_packet *dhcppkt;
1254 	struct dhcphdr *dhcphdr;
1255 	uint8_t msgtype = 0;
1256 	struct in_addr server_id = { 0 };
1257 	int rc = 0;
1258 
1259 	/* Sanity checks */
1260 	if ( ! meta->src ) {
1261 		DBGC ( dhcp, "DHCP %p received packet without source port\n",
1262 		       dhcp );
1263 		rc = -EINVAL;
1264 		goto err_no_src;
1265 	}
1266 	peer = ( struct sockaddr_in * ) meta->src;
1267 
1268 	/* Create a DHCP packet containing the I/O buffer contents.
1269 	 * Whilst we could just use the original buffer in situ, that
1270 	 * would waste the unused space in the packet buffer, and also
1271 	 * waste a relatively scarce fully-aligned I/O buffer.
1272 	 */
1273 	data_len = iob_len ( iobuf );
1274 	dhcppkt = zalloc ( sizeof ( *dhcppkt ) + data_len );
1275 	if ( ! dhcppkt ) {
1276 		rc = -ENOMEM;
1277 		goto err_alloc_dhcppkt;
1278 	}
1279 	dhcphdr = ( ( ( void * ) dhcppkt ) + sizeof ( *dhcppkt ) );
1280 	memcpy ( dhcphdr, iobuf->data, data_len );
1281 	dhcppkt_init ( dhcppkt, dhcphdr, data_len );
1282 
1283 	/* Identify message type */
1284 	dhcppkt_fetch ( dhcppkt, DHCP_MESSAGE_TYPE, &msgtype,
1285 			sizeof ( msgtype ) );
1286 
1287 	/* Identify server ID */
1288 	dhcppkt_fetch ( dhcppkt, DHCP_SERVER_IDENTIFIER,
1289 			&server_id, sizeof ( server_id ) );
1290 
1291 	/* Check for matching transaction ID */
1292 	if ( dhcphdr->xid != dhcp_xid ( dhcp->netdev ) ) {
1293 		DBGC ( dhcp, "DHCP %p %s from %s:%d has bad transaction "
1294 		       "ID\n", dhcp, dhcp_msgtype_name ( msgtype ),
1295 		       inet_ntoa ( peer->sin_addr ),
1296 		       ntohs ( peer->sin_port ) );
1297 		rc = -EINVAL;
1298 		goto err_xid;
1299 	};
1300 
1301 	/* Handle packet based on current state */
1302 	dhcp->state->rx ( dhcp, dhcppkt, peer, msgtype, server_id );
1303 
1304  err_xid:
1305 	dhcppkt_put ( dhcppkt );
1306  err_alloc_dhcppkt:
1307  err_no_src:
1308 	free_iob ( iobuf );
1309 	return rc;
1310 }
1311 
1312 /** DHCP data transfer interface operations */
1313 static struct xfer_interface_operations dhcp_xfer_operations = {
1314 	.close		= ignore_xfer_close,
1315 	.vredirect	= xfer_vreopen,
1316 	.window		= unlimited_xfer_window,
1317 	.alloc_iob	= default_xfer_alloc_iob,
1318 	.deliver_iob	= dhcp_deliver_iob,
1319 	.deliver_raw	= xfer_deliver_as_iob,
1320 };
1321 
1322 /**
1323  * Handle DHCP retry timer expiry
1324  *
1325  * @v timer		DHCP retry timer
1326  * @v fail		Failure indicator
1327  */
dhcp_timer_expired(struct retry_timer * timer,int fail)1328 static void dhcp_timer_expired ( struct retry_timer *timer, int fail ) {
1329 	struct dhcp_session *dhcp =
1330 		container_of ( timer, struct dhcp_session, timer );
1331 
1332 	/* If we have failed, terminate DHCP */
1333 	if ( fail ) {
1334 		dhcp_finished ( dhcp, -ETIMEDOUT );
1335 		return;
1336 	}
1337 
1338 	/* Handle timer expiry based on current state */
1339 	dhcp->state->expired ( dhcp );
1340 }
1341 
1342 /****************************************************************************
1343  *
1344  * Job control interface
1345  *
1346  */
1347 
1348 /**
1349  * Handle kill() event received via job control interface
1350  *
1351  * @v job		DHCP job control interface
1352  */
dhcp_job_kill(struct job_interface * job)1353 static void dhcp_job_kill ( struct job_interface *job ) {
1354 	struct dhcp_session *dhcp =
1355 		container_of ( job, struct dhcp_session, job );
1356 
1357 	/* Terminate DHCP session */
1358 	dhcp_finished ( dhcp, -ECANCELED );
1359 }
1360 
1361 /** DHCP job control interface operations */
1362 static struct job_interface_operations dhcp_job_operations = {
1363 	.done		= ignore_job_done,
1364 	.kill		= dhcp_job_kill,
1365 	.progress	= ignore_job_progress,
1366 };
1367 
1368 /****************************************************************************
1369  *
1370  * Instantiators
1371  *
1372  */
1373 
1374 /**
1375  * DHCP peer address for socket opening
1376  *
1377  * This is a dummy address; the only useful portion is the socket
1378  * family (so that we get a UDP connection).  The DHCP client will set
1379  * the IP address and source port explicitly on each transmission.
1380  */
1381 static struct sockaddr dhcp_peer = {
1382 	.sa_family = AF_INET,
1383 };
1384 
1385 /**
1386  * Start DHCP state machine on a network device
1387  *
1388  * @v job		Job control interface
1389  * @v netdev		Network device
1390  * @ret rc		Return status code, or positive if cached
1391  *
1392  * Starts DHCP on the specified network device.  If successful, the
1393  * DHCPACK (and ProxyDHCPACK, if applicable) will be registered as
1394  * option sources.
1395  *
1396  * On a return of 0, a background job has been started to perform the
1397  * DHCP request. Any nonzero return means the job has not been
1398  * started; a positive return value indicates the success condition of
1399  * having fetched the appropriate data from cached information.
1400  */
start_dhcp(struct job_interface * job,struct net_device * netdev)1401 int start_dhcp ( struct job_interface *job, struct net_device *netdev ) {
1402 	struct dhcp_session *dhcp;
1403 	int rc;
1404 
1405 	/* Check for cached DHCP information */
1406 	get_cached_dhcpack();
1407 	if ( fetch_uintz_setting ( NULL, &use_cached_setting ) ) {
1408 		DBG ( "DHCP using cached network settings\n" );
1409 		return 1;
1410 	}
1411 
1412 	/* Allocate and initialise structure */
1413 	dhcp = zalloc ( sizeof ( *dhcp ) );
1414 	if ( ! dhcp )
1415 		return -ENOMEM;
1416 	dhcp->refcnt.free = dhcp_free;
1417 	job_init ( &dhcp->job, &dhcp_job_operations, &dhcp->refcnt );
1418 	xfer_init ( &dhcp->xfer, &dhcp_xfer_operations, &dhcp->refcnt );
1419 	dhcp->netdev = netdev_get ( netdev );
1420 	dhcp->local.sin_family = AF_INET;
1421 	dhcp->local.sin_port = htons ( BOOTPC_PORT );
1422 	dhcp->timer.expired = dhcp_timer_expired;
1423 
1424 	/* Instantiate child objects and attach to our interfaces */
1425 	if ( ( rc = xfer_open_socket ( &dhcp->xfer, SOCK_DGRAM, &dhcp_peer,
1426 				  ( struct sockaddr * ) &dhcp->local ) ) != 0 )
1427 		goto err;
1428 
1429 	/* Enter DHCPDISCOVER state */
1430 	dhcp_set_state ( dhcp, &dhcp_state_discover );
1431 
1432 	/* Attach parent interface, mortalise self, and return */
1433 	job_plug_plug ( &dhcp->job, job );
1434 	ref_put ( &dhcp->refcnt );
1435 	return 0;
1436 
1437  err:
1438 	dhcp_finished ( dhcp, rc );
1439 	ref_put ( &dhcp->refcnt );
1440 	return rc;
1441 }
1442 
1443 /**
1444  * Retrieve list of PXE boot servers for a given server type
1445  *
1446  * @v dhcp		DHCP session
1447  * @v raw		DHCP PXE boot server list
1448  * @v raw_len		Length of DHCP PXE boot server list
1449  * @v ip		IP address list to fill in
1450  *
1451  * The caller must ensure that the IP address list has sufficient
1452  * space.
1453  */
pxebs_list(struct dhcp_session * dhcp,void * raw,size_t raw_len,struct in_addr * ip)1454 static void pxebs_list ( struct dhcp_session *dhcp, void *raw,
1455 			 size_t raw_len, struct in_addr *ip ) {
1456 	struct dhcp_pxe_boot_server *server = raw;
1457 	size_t server_len;
1458 	unsigned int i;
1459 
1460 	while ( raw_len ) {
1461 		if ( raw_len < sizeof ( *server ) ) {
1462 			DBGC ( dhcp, "DHCP %p malformed PXE server list\n",
1463 			       dhcp );
1464 			break;
1465 		}
1466 		server_len = offsetof ( typeof ( *server ),
1467 					ip[ server->num_ip ] );
1468 		if ( raw_len < server_len ) {
1469 			DBGC ( dhcp, "DHCP %p malformed PXE server list\n",
1470 			       dhcp );
1471 			break;
1472 		}
1473 		if ( server->type == dhcp->pxe_type ) {
1474 			for ( i = 0 ; i < server->num_ip ; i++ )
1475 				*(ip++) = server->ip[i];
1476 		}
1477 		server = ( ( ( void * ) server ) + server_len );
1478 		raw_len -= server_len;
1479 	}
1480 }
1481 
1482 /**
1483  * Start PXE Boot Server Discovery on a network device
1484  *
1485  * @v job		Job control interface
1486  * @v netdev		Network device
1487  * @v pxe_type		PXE server type
1488  * @ret rc		Return status code
1489  *
1490  * Starts PXE Boot Server Discovery on the specified network device.
1491  * If successful, the Boot Server ACK will be registered as an option
1492  * source.
1493  */
start_pxebs(struct job_interface * job,struct net_device * netdev,unsigned int pxe_type)1494 int start_pxebs ( struct job_interface *job, struct net_device *netdev,
1495 		  unsigned int pxe_type ) {
1496 	struct setting pxe_discovery_control_setting =
1497 		{ .tag = DHCP_PXE_DISCOVERY_CONTROL };
1498 	struct setting pxe_boot_servers_setting =
1499 		{ .tag = DHCP_PXE_BOOT_SERVERS };
1500 	struct setting pxe_boot_server_mcast_setting =
1501 		{ .tag = DHCP_PXE_BOOT_SERVER_MCAST };
1502 	ssize_t pxebs_list_len;
1503 	struct dhcp_session *dhcp;
1504 	struct in_addr *ip;
1505 	unsigned int pxe_discovery_control;
1506 	int rc;
1507 
1508 	/* Get upper bound for PXE boot server IP address list */
1509 	pxebs_list_len = fetch_setting_len ( NULL, &pxe_boot_servers_setting );
1510 	if ( pxebs_list_len < 0 )
1511 		pxebs_list_len = 0;
1512 
1513 	/* Allocate and initialise structure */
1514 	dhcp = zalloc ( sizeof ( *dhcp ) + sizeof ( *ip ) /* mcast */ +
1515 			sizeof ( *ip ) /* bcast */ + pxebs_list_len +
1516 			sizeof ( *ip ) /* terminator */ );
1517 	if ( ! dhcp )
1518 		return -ENOMEM;
1519 	dhcp->refcnt.free = dhcp_free;
1520 	job_init ( &dhcp->job, &dhcp_job_operations, &dhcp->refcnt );
1521 	xfer_init ( &dhcp->xfer, &dhcp_xfer_operations, &dhcp->refcnt );
1522 	dhcp->netdev = netdev_get ( netdev );
1523 	dhcp->local.sin_family = AF_INET;
1524 	fetch_ipv4_setting ( netdev_settings ( netdev ), &ip_setting,
1525 			     &dhcp->local.sin_addr );
1526 	dhcp->local.sin_port = htons ( BOOTPC_PORT );
1527 	dhcp->pxe_type = cpu_to_le16 ( pxe_type );
1528 	dhcp->timer.expired = dhcp_timer_expired;
1529 
1530 	/* Construct PXE boot server IP address lists */
1531 	pxe_discovery_control =
1532 		fetch_uintz_setting ( NULL, &pxe_discovery_control_setting );
1533 	ip = ( ( ( void * ) dhcp ) + sizeof ( *dhcp ) );
1534 	dhcp->pxe_attempt = ip;
1535 	if ( ! ( pxe_discovery_control & PXEBS_NO_MULTICAST ) ) {
1536 		fetch_ipv4_setting ( NULL, &pxe_boot_server_mcast_setting, ip);
1537 		if ( ip->s_addr )
1538 			ip++;
1539 	}
1540 	if ( ! ( pxe_discovery_control & PXEBS_NO_BROADCAST ) )
1541 		(ip++)->s_addr = INADDR_BROADCAST;
1542 	if ( pxe_discovery_control & PXEBS_NO_UNKNOWN_SERVERS )
1543 		dhcp->pxe_accept = ip;
1544 	if ( pxebs_list_len ) {
1545 		uint8_t buf[pxebs_list_len];
1546 
1547 		fetch_setting ( NULL, &pxe_boot_servers_setting,
1548 				buf, sizeof ( buf ) );
1549 		pxebs_list ( dhcp, buf, sizeof ( buf ), ip );
1550 	}
1551 	if ( ! dhcp->pxe_attempt->s_addr ) {
1552 		DBGC ( dhcp, "DHCP %p has no PXE boot servers for type %04x\n",
1553 		       dhcp, pxe_type );
1554 		rc = -EINVAL;
1555 		goto err;
1556 	}
1557 
1558 	/* Dump out PXE server lists */
1559 	DBGC ( dhcp, "DHCP %p attempting", dhcp );
1560 	for ( ip = dhcp->pxe_attempt ; ip->s_addr ; ip++ )
1561 		DBGC ( dhcp, " %s", inet_ntoa ( *ip ) );
1562 	DBGC ( dhcp, "\n" );
1563 	if ( dhcp->pxe_accept ) {
1564 		DBGC ( dhcp, "DHCP %p accepting", dhcp );
1565 		for ( ip = dhcp->pxe_accept ; ip->s_addr ; ip++ )
1566 			DBGC ( dhcp, " %s", inet_ntoa ( *ip ) );
1567 		DBGC ( dhcp, "\n" );
1568 	}
1569 
1570 	/* Instantiate child objects and attach to our interfaces */
1571 	if ( ( rc = xfer_open_socket ( &dhcp->xfer, SOCK_DGRAM, &dhcp_peer,
1572 				  ( struct sockaddr * ) &dhcp->local ) ) != 0 )
1573 		goto err;
1574 
1575 	/* Enter PXEBS state */
1576 	dhcp_set_state ( dhcp, &dhcp_state_pxebs );
1577 
1578 	/* Attach parent interface, mortalise self, and return */
1579 	job_plug_plug ( &dhcp->job, job );
1580 	ref_put ( &dhcp->refcnt );
1581 	return 0;
1582 
1583  err:
1584 	dhcp_finished ( dhcp, rc );
1585 	ref_put ( &dhcp->refcnt );
1586 	return rc;
1587 }
1588