xref: /netbsd-src/sys/nfs/nfs_boot.c (revision cac8e449158efc7261bebc8657cbb0125a2cfdde)
1 /*	$NetBSD: nfs_boot.c,v 1.73 2008/05/22 00:57:09 dyoung Exp $	*/
2 
3 /*-
4  * Copyright (c) 1995, 1997 The NetBSD Foundation, Inc.
5  * All rights reserved.
6  *
7  * This code is derived from software contributed to The NetBSD Foundation
8  * by Adam Glass and Gordon W. Ross.
9  *
10  * Redistribution and use in source and binary forms, with or without
11  * modification, are permitted provided that the following conditions
12  * are met:
13  * 1. Redistributions of source code must retain the above copyright
14  *    notice, this list of conditions and the following disclaimer.
15  * 2. Redistributions in binary form must reproduce the above copyright
16  *    notice, this list of conditions and the following disclaimer in the
17  *    documentation and/or other materials provided with the distribution.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29  * POSSIBILITY OF SUCH DAMAGE.
30  */
31 
32 /*
33  * Support for NFS diskless booting, specifically getting information
34  * about where to mount root from, what pathnames, etc.
35  */
36 
37 #include <sys/cdefs.h>
38 __KERNEL_RCSID(0, "$NetBSD: nfs_boot.c,v 1.73 2008/05/22 00:57:09 dyoung Exp $");
39 
40 #include "opt_nfs.h"
41 #include "opt_tftproot.h"
42 #include "opt_nfs_boot.h"
43 
44 #include <sys/param.h>
45 #include <sys/systm.h>
46 #include <sys/kernel.h>
47 #include <sys/device.h>
48 #include <sys/ioctl.h>
49 #include <sys/proc.h>
50 #include <sys/mount.h>
51 #include <sys/mbuf.h>
52 #include <sys/reboot.h>
53 #include <sys/socket.h>
54 #include <sys/socketvar.h>
55 
56 #include <net/if.h>
57 #include <net/route.h>
58 #include <net/if_ether.h>
59 #include <net/if_types.h>
60 
61 #include <netinet/in.h>
62 #include <netinet/if_inarp.h>
63 
64 #include <nfs/rpcv2.h>
65 #include <nfs/krpc.h>
66 #include <nfs/xdr_subs.h>
67 
68 #include <nfs/nfsproto.h>
69 #include <nfs/nfs.h>
70 #include <nfs/nfsmount.h>
71 #include <nfs/nfsdiskless.h>
72 
73 /*
74  * There are two implementations of NFS diskless boot.
75  * One implementation uses BOOTP (RFC951, RFC1048),
76  * the other uses Sun RPC/bootparams.  See the files:
77  *    nfs_bootp.c:   BOOTP (RFC951, RFC1048)
78  *    nfs_bootsun.c: Sun RPC/bootparams
79  */
80 #if defined(NFS_BOOT_BOOTP) || defined(NFS_BOOT_DHCP)
81 int nfs_boot_rfc951 = 1; /* BOOTP enabled (default) */
82 #endif
83 #ifdef NFS_BOOT_BOOTPARAM
84 int nfs_boot_bootparam = 1; /* BOOTPARAM enabled (default) */
85 #endif
86 #ifdef NFS_BOOT_BOOTSTATIC
87 int nfs_boot_bootstatic = 1; /* BOOTSTATIC enabled (default) */
88 #endif
89 
90 /* mountd RPC */
91 static int md_mount(struct sockaddr_in *mdsin, char *path,
92 	struct nfs_args *argp, struct lwp *l);
93 
94 static int nfs_boot_delroute(struct rtentry *, void *);
95 static void nfs_boot_defrt(struct in_addr *);
96 static  int nfs_boot_getfh(struct nfs_dlmount *ndm, struct lwp *);
97 
98 
99 /*
100  * Called with an empty nfs_diskless struct to be filled in.
101  * Find an interface, determine its ip address (etc.) and
102  * save all the boot parameters in the nfs_diskless struct.
103  */
104 int
105 nfs_boot_init(nd, lwp)
106 	struct nfs_diskless *nd;
107 	struct lwp *lwp;
108 {
109 	struct ifnet *ifp;
110 	int error = 0;
111 
112 	/*
113 	 * Find the network interface.
114 	 */
115 	ifp = ifunit(device_xname(root_device));
116 	if (ifp == NULL) {
117 		printf("nfs_boot: '%s' not found\n",
118 		       device_xname(root_device));
119 		return (ENXIO);
120 	}
121 	nd->nd_ifp = ifp;
122 
123 	error = EADDRNOTAVAIL; /* ??? */
124 #if defined(NFS_BOOT_BOOTSTATIC)
125 	if (error && nfs_boot_bootstatic) {
126 		printf("nfs_boot: trying static\n");
127 		error = nfs_bootstatic(nd, lwp);
128 	}
129 #endif
130 #if defined(NFS_BOOT_BOOTP) || defined(NFS_BOOT_DHCP)
131 	if (error && nfs_boot_rfc951) {
132 #if defined(NFS_BOOT_DHCP)
133 		printf("nfs_boot: trying DHCP/BOOTP\n");
134 #else
135 		printf("nfs_boot: trying BOOTP\n");
136 #endif
137 		error = nfs_bootdhcp(nd, lwp);
138 	}
139 #endif
140 #ifdef NFS_BOOT_BOOTPARAM
141 	if (error && nfs_boot_bootparam) {
142 		printf("nfs_boot: trying RARP (and RPC/bootparam)\n");
143 		error = nfs_bootparam(nd, lwp);
144 	}
145 #endif
146 	if (error)
147 		return (error);
148 
149 	/*
150 	 * If the gateway address is set, add a default route.
151 	 * (The mountd RPCs may go across a gateway.)
152 	 */
153 	if (nd->nd_gwip.s_addr)
154 		nfs_boot_defrt(&nd->nd_gwip);
155 
156 #ifdef TFTPROOT
157 	if (nd->nd_nomount)
158 		goto out;
159 #endif
160 	/*
161 	 * Now fetch the NFS file handles as appropriate.
162 	 */
163 	error = nfs_boot_getfh(&nd->nd_root, lwp);
164 
165 	if (error)
166 		nfs_boot_cleanup(nd, lwp);
167 
168 #ifdef TFTPROOT
169 out:
170 #endif
171 	return (error);
172 }
173 
174 void
175 nfs_boot_cleanup(nd, lwp)
176 	struct nfs_diskless *nd;
177 	struct lwp *lwp;
178 {
179 
180 	nfs_boot_deladdress(nd->nd_ifp, lwp, nd->nd_myip.s_addr);
181 	nfs_boot_ifupdown(nd->nd_ifp, lwp, 0);
182 	nfs_boot_flushrt(nd->nd_ifp);
183 }
184 
185 int
186 nfs_boot_ifupdown(ifp, lwp, up)
187 	struct ifnet *ifp;
188 	struct lwp *lwp;
189 	int up;
190 {
191 	struct socket *so;
192 	struct ifreq ireq;
193 	int error;
194 
195 	memset(&ireq, 0, sizeof(ireq));
196 	memcpy(ireq.ifr_name, ifp->if_xname, IFNAMSIZ);
197 
198 	/*
199 	 * Get a socket to use for various things in here.
200 	 * After this, use "goto out" to cleanup and return.
201 	 */
202 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0, lwp, NULL);
203 	if (error) {
204 		printf("ifupdown: socreate, error=%d\n", error);
205 		return (error);
206 	}
207 
208 	/*
209 	 * Bring up the interface. (just set the "up" flag)
210 	 * Get the old interface flags and or IFF_UP into them so
211 	 * things like media selection flags are not clobbered.
212 	 */
213 	error = ifioctl(so, SIOCGIFFLAGS, (void *)&ireq, lwp);
214 	if (error) {
215 		printf("ifupdown: GIFFLAGS, error=%d\n", error);
216 		goto out;
217 	}
218 	if (up)
219 		ireq.ifr_flags |= IFF_UP;
220 	else
221 		ireq.ifr_flags &= ~IFF_UP;
222 	error = ifioctl(so, SIOCSIFFLAGS, &ireq, lwp);
223 	if (error) {
224 		printf("ifupdown: SIFFLAGS, error=%d\n", error);
225 		goto out;
226 	}
227 
228 	if (up)
229 		/* give the link some time to get up */
230 		tsleep(nfs_boot_ifupdown, PZERO, "nfsbif", 3 * hz);
231 out:
232 	soclose(so);
233 	return (error);
234 }
235 
236 int
237 nfs_boot_setaddress(ifp, lwp, addr, netmask, braddr)
238 	struct ifnet *ifp;
239 	struct lwp *lwp;
240 	u_int32_t addr, netmask, braddr;
241 {
242 	struct socket *so;
243 	struct ifaliasreq iareq;
244 	struct sockaddr_in *sin;
245 	int error;
246 
247 	/*
248 	 * Get a socket to use for various things in here.
249 	 * After this, use "goto out" to cleanup and return.
250 	 */
251 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0, lwp, NULL);
252 	if (error) {
253 		printf("setaddress: socreate, error=%d\n", error);
254 		return (error);
255 	}
256 
257 	memset(&iareq, 0, sizeof(iareq));
258 	memcpy(iareq.ifra_name, ifp->if_xname, IFNAMSIZ);
259 
260 	/* Set the I/F address */
261 	sin = (struct sockaddr_in *)&iareq.ifra_addr;
262 	sin->sin_len = sizeof(*sin);
263 	sin->sin_family = AF_INET;
264 	sin->sin_addr.s_addr = addr;
265 
266 	/* Set the netmask */
267 	if (netmask != INADDR_ANY) {
268 		sin = (struct sockaddr_in *)&iareq.ifra_mask;
269 		sin->sin_len = sizeof(*sin);
270 		sin->sin_family = AF_INET;
271 		sin->sin_addr.s_addr = netmask;
272 	} /* else leave subnetmask unspecified (len=0) */
273 
274 	/* Set the broadcast addr. */
275 	if (braddr != INADDR_ANY) {
276 		sin = (struct sockaddr_in *)&iareq.ifra_broadaddr;
277 		sin->sin_len = sizeof(*sin);
278 		sin->sin_family = AF_INET;
279 		sin->sin_addr.s_addr = braddr;
280 	} /* else leave broadcast addr unspecified (len=0) */
281 
282 	error = ifioctl(so, SIOCAIFADDR, (void *)&iareq, lwp);
283 	if (error) {
284 		printf("setaddress, error=%d\n", error);
285 		goto out;
286 	}
287 
288 	/* give the link some time to get up */
289 	tsleep(nfs_boot_setaddress, PZERO, "nfsbtd", 3 * hz);
290 out:
291 	soclose(so);
292 	return (error);
293 }
294 
295 int
296 nfs_boot_deladdress(ifp, lwp, addr)
297 	struct ifnet *ifp;
298 	struct lwp *lwp;
299 	u_int32_t addr;
300 {
301 	struct socket *so;
302 	struct ifreq ifr;
303 	struct sockaddr_in sin;
304 	struct in_addr ia = {.s_addr = addr};
305 	int error;
306 
307 	/*
308 	 * Get a socket to use for various things in here.
309 	 * After this, use "goto out" to cleanup and return.
310 	 */
311 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0, lwp, NULL);
312 	if (error) {
313 		printf("deladdress: socreate, error=%d\n", error);
314 		return (error);
315 	}
316 
317 	memset(&ifr, 0, sizeof(ifr));
318 	memcpy(ifr.ifr_name, ifp->if_xname, IFNAMSIZ);
319 
320 	sockaddr_in_init(&sin, &ia, 0);
321 	ifreq_setaddr(SIOCDIFADDR, &ifr, sintocsa(&sin));
322 
323 	error = ifioctl(so, SIOCDIFADDR, &ifr, lwp);
324 	if (error) {
325 		printf("deladdress, error=%d\n", error);
326 		goto out;
327 	}
328 
329 out:
330 	soclose(so);
331 	return (error);
332 }
333 
334 int
335 nfs_boot_setrecvtimo(so)
336 	struct socket *so;
337 {
338 	struct mbuf *m;
339 	struct timeval *tv;
340 
341 	m = m_get(M_WAIT, MT_SOOPTS);
342 	tv = mtod(m, struct timeval *);
343 	m->m_len = sizeof(*tv);
344 	tv->tv_sec = 1;
345 	tv->tv_usec = 0;
346 	return (sosetopt(so, SOL_SOCKET, SO_RCVTIMEO, m));
347 }
348 
349 int
350 nfs_boot_enbroadcast(so)
351 	struct socket *so;
352 {
353 	struct mbuf *m;
354 	int32_t *on;
355 
356 	m = m_get(M_WAIT, MT_SOOPTS);
357 	on = mtod(m, int32_t *);
358 	m->m_len = sizeof(*on);
359 	*on = 1;
360 	return (sosetopt(so, SOL_SOCKET, SO_BROADCAST, m));
361 }
362 
363 int
364 nfs_boot_sobind_ipport(so, port, l)
365 	struct socket *so;
366 	u_int16_t port;
367 	struct lwp *l;
368 {
369 	struct mbuf *m;
370 	struct sockaddr_in *sin;
371 	int error;
372 
373 	m = m_getclr(M_WAIT, MT_SONAME);
374 	sin = mtod(m, struct sockaddr_in *);
375 	sin->sin_len = m->m_len = sizeof(*sin);
376 	sin->sin_family = AF_INET;
377 	sin->sin_addr.s_addr = INADDR_ANY;
378 	sin->sin_port = htons(port);
379 	error = sobind(so, m, l);
380 	m_freem(m);
381 	return (error);
382 }
383 
384 /*
385  * What is the longest we will wait before re-sending a request?
386  * Note this is also the frequency of "timeout" messages.
387  * The re-send loop counts up linearly to this maximum, so the
388  * first complaint will happen after (1+2+3+4+5)=15 seconds.
389  */
390 #define	MAX_RESEND_DELAY 5	/* seconds */
391 #define TOTAL_TIMEOUT   30	/* seconds */
392 
393 int
394 nfs_boot_sendrecv(so, nam, sndproc, snd, rcvproc, rcv, from_p, context, lwp)
395 	struct socket *so;
396 	struct mbuf *nam;
397 	int (*sndproc)(struct mbuf*, void*, int);
398 	struct mbuf *snd;
399 	int (*rcvproc)(struct mbuf*, void*);
400 	struct mbuf **rcv, **from_p;
401 	void *context;
402 	struct lwp *lwp;
403 {
404 	int error, rcvflg, timo, secs, waited;
405 	struct mbuf *m, *from;
406 	struct uio uio;
407 
408 	/* Free at end if not null. */
409 	from = NULL;
410 
411 	/*
412 	 * Send it, repeatedly, until a reply is received,
413 	 * but delay each re-send by an increasing amount.
414 	 * If the delay hits the maximum, start complaining.
415 	 */
416 	waited = timo = 0;
417 send_again:
418 	waited += timo;
419 	if (waited >= TOTAL_TIMEOUT)
420 		return (ETIMEDOUT);
421 
422 	/* Determine new timeout. */
423 	if (timo < MAX_RESEND_DELAY)
424 		timo++;
425 	else
426 		printf("nfs_boot: timeout...\n");
427 
428 	if (sndproc) {
429 		error = (*sndproc)(snd, context, waited);
430 		if (error)
431 			goto out;
432 	}
433 
434 	/* Send request (or re-send). */
435 	m = m_copypacket(snd, M_WAIT);
436 	if (m == NULL) {
437 		error = ENOBUFS;
438 		goto out;
439 	}
440 	error = (*so->so_send)(so, nam, NULL, m, NULL, 0, lwp);
441 	if (error) {
442 		printf("nfs_boot: sosend: %d\n", error);
443 		goto out;
444 	}
445 	m = NULL;
446 
447 	/*
448 	 * Wait for up to timo seconds for a reply.
449 	 * The socket receive timeout was set to 1 second.
450 	 */
451 
452 	secs = timo;
453 	for (;;) {
454 		if (from) {
455 			m_freem(from);
456 			from = NULL;
457 		}
458 		if (m) {
459 			m_freem(m);
460 			m = NULL;
461 		}
462 		uio.uio_resid = 1 << 16; /* ??? */
463 		rcvflg = 0;
464 		error = (*so->so_receive)(so, &from, &uio, &m, NULL, &rcvflg);
465 		if (error == EWOULDBLOCK) {
466 			if (--secs <= 0)
467 				goto send_again;
468 			continue;
469 		}
470 		if (error)
471 			goto out;
472 #ifdef DIAGNOSTIC
473 		if (!m || !(m->m_flags & M_PKTHDR)
474 		    || (1 << 16) - uio.uio_resid != m->m_pkthdr.len)
475 			panic("nfs_boot_sendrecv: return size");
476 #endif
477 
478 		if ((*rcvproc)(m, context))
479 			continue;
480 
481 		if (rcv)
482 			*rcv = m;
483 		else
484 			m_freem(m);
485 		if (from_p) {
486 			*from_p = from;
487 			from = NULL;
488 		}
489 		break;
490 	}
491 out:
492 	if (from) m_freem(from);
493 	return (error);
494 }
495 
496 /*
497  * Install a default route to the passed IP address.
498  */
499 static void
500 nfs_boot_defrt(gw_ip)
501 	struct in_addr *gw_ip;
502 {
503 	struct sockaddr dst, gw, mask;
504 	struct sockaddr_in *sin;
505 	int error;
506 
507 	/* Destination: (default) */
508 	memset((void *)&dst, 0, sizeof(dst));
509 	dst.sa_len = sizeof(dst);
510 	dst.sa_family = AF_INET;
511 	/* Gateway: */
512 	memset((void *)&gw, 0, sizeof(gw));
513 	sin = (struct sockaddr_in *)&gw;
514 	sin->sin_len = sizeof(*sin);
515 	sin->sin_family = AF_INET;
516 	sin->sin_addr.s_addr = gw_ip->s_addr;
517 	/* Mask: (zero length) */
518 	/* XXX - Just pass a null pointer? */
519 	memset(&mask, 0, sizeof(mask));
520 
521 	/* add, dest, gw, mask, flags, 0 */
522 	error = rtrequest(RTM_ADD, &dst, &gw, &mask,
523 			  (RTF_UP | RTF_GATEWAY | RTF_STATIC), NULL);
524 	if (error) {
525 		printf("nfs_boot: add route, error=%d\n", error);
526 		error = 0;
527 	}
528 }
529 
530 static int
531 nfs_boot_delroute(struct rtentry *rt, void *w)
532 {
533 	int error;
534 
535 	if ((void *)rt->rt_ifp != w)
536 		return 0;
537 
538 	error = rtrequest(RTM_DELETE, rt_getkey(rt), NULL, rt_mask(rt), 0,
539 	    NULL);
540 	if (error != 0)
541 		printf("%s: del route, error=%d\n", __func__, error);
542 
543 	return 0;
544 }
545 
546 void
547 nfs_boot_flushrt(struct ifnet *ifp)
548 {
549 
550 	rt_walktree(AF_INET, nfs_boot_delroute, ifp);
551 }
552 
553 /*
554  * Get an initial NFS file handle using Sun RPC/mountd.
555  * Separate function because we used to call it twice.
556  * (once for root and once for swap)
557  */
558 static int
559 nfs_boot_getfh(ndm, l)
560 	struct nfs_dlmount *ndm;	/* output */
561 	struct lwp *l;
562 {
563 	struct nfs_args *args;
564 	struct sockaddr_in *sin;
565 	char *pathname;
566 	int error;
567 	u_int16_t port;
568 
569 	args = &ndm->ndm_args;
570 
571 	/* Initialize mount args. */
572 	memset((void *) args, 0, sizeof(*args));
573 	args->addr     = &ndm->ndm_saddr;
574 	args->addrlen  = args->addr->sa_len;
575 #ifdef NFS_BOOT_TCP
576 	args->sotype   = SOCK_STREAM;
577 #else
578 	args->sotype   = SOCK_DGRAM;
579 #endif
580 	args->fh       = ndm->ndm_fh;
581 	args->hostname = ndm->ndm_host;
582 	args->flags    = NFSMNT_NOCONN | NFSMNT_RESVPORT;
583 
584 #ifndef NFS_V2_ONLY
585 	args->flags    |= NFSMNT_NFSV3;
586 #endif
587 #ifdef	NFS_BOOT_OPTIONS
588 	args->flags    |= NFS_BOOT_OPTIONS;
589 #endif
590 #ifdef	NFS_BOOT_RWSIZE
591 	/*
592 	 * Reduce rsize,wsize for interfaces that consistently
593 	 * drop fragments of long UDP messages.  (i.e. wd8003).
594 	 * You can always change these later via remount.
595 	 */
596 	args->flags   |= NFSMNT_WSIZE | NFSMNT_RSIZE;
597 	args->wsize    = NFS_BOOT_RWSIZE;
598 	args->rsize    = NFS_BOOT_RWSIZE;
599 #endif
600 
601 	/*
602 	 * Find the pathname part of the "server:pathname"
603 	 * string left in ndm->ndm_host by nfs_boot_init.
604 	 */
605 	pathname = strchr(ndm->ndm_host, ':');
606 	if (pathname == 0) {
607 		printf("nfs_boot: getfh - no pathname\n");
608 		return (EIO);
609 	}
610 	pathname++;
611 
612 	/*
613 	 * Get file handle using RPC to mountd/mount
614 	 */
615 	sin = (struct sockaddr_in *)&ndm->ndm_saddr;
616 	error = md_mount(sin, pathname, args, l);
617 	if (error) {
618 		printf("nfs_boot: mountd `%s', error=%d\n",
619 		       ndm->ndm_host, error);
620 		return (error);
621 	}
622 
623 	/* Set port number for NFS use. */
624 	/* XXX: NFS port is always 2049, right? */
625 #ifdef NFS_BOOT_TCP
626 retry:
627 #endif
628 	error = krpc_portmap(sin, NFS_PROG,
629 		    (args->flags & NFSMNT_NFSV3) ? NFS_VER3 : NFS_VER2,
630 		    (args->sotype == SOCK_STREAM) ? IPPROTO_TCP : IPPROTO_UDP,
631 		    &port, l);
632 	if (port == htons(0))
633 		error = EIO;
634 	if (error) {
635 #ifdef NFS_BOOT_TCP
636 		if (args->sotype == SOCK_STREAM) {
637 			args->sotype = SOCK_DGRAM;
638 			goto retry;
639 		}
640 #endif
641 		printf("nfs_boot: portmap NFS, error=%d\n", error);
642 		return (error);
643 	}
644 	sin->sin_port = port;
645 	return (0);
646 }
647 
648 
649 /*
650  * RPC: mountd/mount
651  * Given a server pathname, get an NFS file handle.
652  * Also, sets sin->sin_port to the NFS service port.
653  */
654 static int
655 md_mount(mdsin, path, argp, lwp)
656 	struct sockaddr_in *mdsin;		/* mountd server address */
657 	char *path;
658 	struct nfs_args *argp;
659 	struct lwp *lwp;
660 {
661 	/* The RPC structures */
662 	struct rdata {
663 		u_int32_t errno;
664 		union {
665 			u_int8_t  v2fh[NFSX_V2FH];
666 			struct {
667 				u_int32_t fhlen;
668 				u_int8_t  fh[1];
669 			} v3fh;
670 		} fh;
671 	} *rdata;
672 	struct mbuf *m;
673 	u_int8_t *fh;
674 	int minlen, error;
675 	int mntver;
676 
677 	mntver = (argp->flags & NFSMNT_NFSV3) ? 3 : 2;
678 	do {
679 		/*
680 		 * Get port number for MOUNTD.
681 		 */
682 		error = krpc_portmap(mdsin, RPCPROG_MNT, mntver,
683 		                    IPPROTO_UDP, &mdsin->sin_port, lwp);
684 		if (error)
685 			continue;
686 
687 		/* This mbuf is consumed by krpc_call. */
688 		m = xdr_string_encode(path, strlen(path));
689 		if (m == NULL)
690 			return ENOMEM;
691 
692 		/* Do RPC to mountd. */
693 		error = krpc_call(mdsin, RPCPROG_MNT, mntver,
694 		                  RPCMNT_MOUNT, &m, NULL, lwp);
695 		if (error != EPROGMISMATCH)
696 			break;
697 		/* Try lower version of mountd. */
698 	} while (--mntver >= 1);
699 	if (error) {
700 		printf("nfs_boot: mountd error=%d\n", error);
701 		return error;
702 	}
703 	if (mntver != 3)
704 		argp->flags &= ~NFSMNT_NFSV3;
705 
706 	/* The reply might have only the errno. */
707 	if (m->m_len < 4)
708 		goto bad;
709 	/* Have at least errno, so check that. */
710 	rdata = mtod(m, struct rdata *);
711 	error = fxdr_unsigned(u_int32_t, rdata->errno);
712 	if (error)
713 		goto out;
714 
715 	/* Have errno==0, so the fh must be there. */
716 	if (mntver == 3) {
717 		argp->fhsize   = fxdr_unsigned(u_int32_t, rdata->fh.v3fh.fhlen);
718 		if (argp->fhsize > NFSX_V3FHMAX)
719 			goto bad;
720 		minlen = 2 * sizeof(u_int32_t) + argp->fhsize;
721 	} else {
722 		argp->fhsize   = NFSX_V2FH;
723 		minlen = sizeof(u_int32_t) + argp->fhsize;
724 	}
725 
726 	if (m->m_len < minlen) {
727 		m = m_pullup(m, minlen);
728 		if (m == NULL)
729 			return(EBADRPC);
730 		rdata = mtod(m, struct rdata *);
731 	}
732 
733 	fh = (mntver == 3) ?
734 		rdata->fh.v3fh.fh : rdata->fh.v2fh;
735 	memcpy(argp->fh, fh, argp->fhsize);
736 
737 	goto out;
738 
739 bad:
740 	error = EBADRPC;
741 
742 out:
743 	m_freem(m);
744 	return error;
745 }
746