xref: /netbsd-src/sys/nfs/nfs_boot.c (revision 5aefcfdc06931dd97e76246d2fe0302f7b3fe094)
1 /*	$NetBSD: nfs_boot.c,v 1.55 2000/12/10 23:17:01 fvdl 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  * 3. All advertising materials mentioning features or use of this software
19  *    must display the following acknowledgement:
20  *	This product includes software developed by the NetBSD
21  *	Foundation, Inc. and its contributors.
22  * 4. Neither the name of The NetBSD Foundation nor the names of its
23  *    contributors may be used to endorse or promote products derived
24  *    from this software without specific prior written permission.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
36  * POSSIBILITY OF SUCH DAMAGE.
37  */
38 
39 /*
40  * Support for NFS diskless booting, specifically getting information
41  * about where to mount root from, what pathnames, etc.
42  */
43 
44 #include "opt_nfs.h"
45 #include "opt_nfs_boot.h"
46 
47 #include <sys/param.h>
48 #include <sys/systm.h>
49 #include <sys/kernel.h>
50 #include <sys/device.h>
51 #include <sys/ioctl.h>
52 #include <sys/proc.h>
53 #include <sys/mount.h>
54 #include <sys/mbuf.h>
55 #include <sys/reboot.h>
56 #include <sys/socket.h>
57 #include <sys/socketvar.h>
58 
59 #include <net/if.h>
60 #include <net/route.h>
61 #include <net/if_ether.h>
62 #include <net/if_types.h>
63 
64 #include <netinet/in.h>
65 #include <netinet/if_inarp.h>
66 
67 #include <nfs/rpcv2.h>
68 #include <nfs/krpc.h>
69 #include <nfs/xdr_subs.h>
70 
71 #include <nfs/nfsproto.h>
72 #include <nfs/nfs.h>
73 #include <nfs/nfsmount.h>
74 #include <nfs/nfsdiskless.h>
75 
76 /*
77  * There are two implementations of NFS diskless boot.
78  * One implementation uses BOOTP (RFC951, RFC1048),
79  * the other uses Sun RPC/bootparams.  See the files:
80  *    nfs_bootp.c:   BOOTP (RFC951, RFC1048)
81  *    nfs_bootsun.c: Sun RPC/bootparams
82  */
83 #if defined(NFS_BOOT_BOOTP) || defined(NFS_BOOT_DHCP)
84 int nfs_boot_rfc951 = 1; /* BOOTP enabled (default) */
85 #endif
86 #ifdef NFS_BOOT_BOOTPARAM
87 int nfs_boot_bootparam = 1; /* BOOTPARAM enabled (default) */
88 #endif
89 
90 /* mountd RPC */
91 static int md_mount __P((struct sockaddr_in *mdsin, char *path,
92 	struct nfs_args *argp));
93 
94 static void nfs_boot_defrt __P((struct in_addr *));
95 static  int nfs_boot_getfh __P((struct nfs_dlmount *ndm));
96 
97 
98 /*
99  * Called with an empty nfs_diskless struct to be filled in.
100  * Find an interface, determine its ip address (etc.) and
101  * save all the boot parameters in the nfs_diskless struct.
102  */
103 int
104 nfs_boot_init(nd, procp)
105 	struct nfs_diskless *nd;
106 	struct proc *procp;
107 {
108 	struct ifnet *ifp;
109 	int error;
110 
111 	/*
112 	 * Find the network interface.
113 	 */
114 	ifp = ifunit(root_device->dv_xname);
115 	if (ifp == NULL) {
116 		printf("nfs_boot: '%s' not found\n",
117 		       root_device->dv_xname);
118 		return (ENXIO);
119 	}
120 	nd->nd_ifp = ifp;
121 
122 	error = EADDRNOTAVAIL; /* ??? */
123 #if defined(NFS_BOOT_BOOTP) || defined(NFS_BOOT_DHCP)
124 	if (error && nfs_boot_rfc951) {
125 #if defined(NFS_BOOT_DHCP)
126 		printf("nfs_boot: trying DHCP/BOOTP\n");
127 #else
128 		printf("nfs_boot: trying BOOTP\n");
129 #endif
130 		error = nfs_bootdhcp(nd, procp);
131 	}
132 #endif
133 #ifdef NFS_BOOT_BOOTPARAM
134 	if (error && nfs_boot_bootparam) {
135 		printf("nfs_boot: trying RARP (and RPC/bootparam)\n");
136 		error = nfs_bootparam(nd, procp);
137 	}
138 #endif
139 	if (error)
140 		return (error);
141 
142 	/*
143 	 * If the gateway address is set, add a default route.
144 	 * (The mountd RPCs may go across a gateway.)
145 	 */
146 	if (nd->nd_gwip.s_addr)
147 		nfs_boot_defrt(&nd->nd_gwip);
148 
149 	/*
150 	 * Now fetch the NFS file handles as appropriate.
151 	 */
152 	error = nfs_boot_getfh(&nd->nd_root);
153 
154 	if (error)
155 		nfs_boot_cleanup(nd, procp);
156 
157 	return (error);
158 }
159 
160 void
161 nfs_boot_cleanup(nd, procp)
162 	struct nfs_diskless *nd;
163 	struct proc *procp;
164 {
165 
166 	nfs_boot_deladdress(nd->nd_ifp, procp, nd->nd_myip.s_addr);
167 	nfs_boot_ifupdown(nd->nd_ifp, procp, 0);
168 	nfs_boot_flushrt(nd->nd_ifp);
169 }
170 
171 int
172 nfs_boot_ifupdown(ifp, procp, up)
173 	struct ifnet *ifp;
174 	struct proc *procp;
175 	int up;
176 {
177 	struct socket *so;
178 	struct ifreq ireq;
179 	int error;
180 
181 	memset(&ireq, 0, sizeof(ireq));
182 	memcpy(ireq.ifr_name, ifp->if_xname, IFNAMSIZ);
183 
184 	/*
185 	 * Get a socket to use for various things in here.
186 	 * After this, use "goto out" to cleanup and return.
187 	 */
188 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
189 	if (error) {
190 		printf("ifupdown: socreate, error=%d\n", error);
191 		return (error);
192 	}
193 
194 	/*
195 	 * Bring up the interface. (just set the "up" flag)
196 	 * Get the old interface flags and or IFF_UP into them so
197 	 * things like media selection flags are not clobbered.
198 	 */
199 	error = ifioctl(so, SIOCGIFFLAGS, (caddr_t)&ireq, procp);
200 	if (error) {
201 		printf("ifupdown: GIFFLAGS, error=%d\n", error);
202 		goto out;
203 	}
204 	if (up)
205 		ireq.ifr_flags |= IFF_UP;
206 	else
207 		ireq.ifr_flags &= ~IFF_UP;
208 	error = ifioctl(so, SIOCSIFFLAGS, (caddr_t)&ireq, procp);
209 	if (error) {
210 		printf("ifupdown: SIFFLAGS, error=%d\n", error);
211 		goto out;
212 	}
213 
214 	if (up)
215 		delay(3000000); /* give the link some time to get up */
216 out:
217 	soclose(so);
218 	return (error);
219 }
220 
221 int
222 nfs_boot_setaddress(ifp, procp, addr, netmask, braddr)
223 	struct ifnet *ifp;
224 	struct proc *procp;
225 	u_int32_t addr, netmask, braddr;
226 {
227 	struct socket *so;
228 	struct ifaliasreq iareq;
229 	struct sockaddr_in *sin;
230 	int error;
231 
232 	/*
233 	 * Get a socket to use for various things in here.
234 	 * After this, use "goto out" to cleanup and return.
235 	 */
236 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
237 	if (error) {
238 		printf("setaddress: socreate, error=%d\n", error);
239 		return (error);
240 	}
241 
242 	memset(&iareq, 0, sizeof(iareq));
243 	memcpy(iareq.ifra_name, ifp->if_xname, IFNAMSIZ);
244 
245 	/* Set the I/F address */
246 	sin = (struct sockaddr_in *)&iareq.ifra_addr;
247 	sin->sin_len = sizeof(*sin);
248 	sin->sin_family = AF_INET;
249 	sin->sin_addr.s_addr = addr;
250 
251 	/* Set the netmask */
252 	if (netmask != INADDR_ANY) {
253 		sin = (struct sockaddr_in *)&iareq.ifra_mask;
254 		sin->sin_len = sizeof(*sin);
255 		sin->sin_family = AF_INET;
256 		sin->sin_addr.s_addr = netmask;
257 	} /* else leave subnetmask unspecified (len=0) */
258 
259 	/* Set the broadcast addr. */
260 	if (braddr != INADDR_ANY) {
261 		sin = (struct sockaddr_in *)&iareq.ifra_broadaddr;
262 		sin->sin_len = sizeof(*sin);
263 		sin->sin_family = AF_INET;
264 		sin->sin_addr.s_addr = braddr;
265 	} /* else leave broadcast addr unspecified (len=0) */
266 
267 	error = ifioctl(so, SIOCAIFADDR, (caddr_t)&iareq, procp);
268 	if (error) {
269 		printf("setaddress, error=%d\n", error);
270 		goto out;
271 	}
272 
273 	delay(3000000); /* give the link some time to get up */
274 out:
275 	soclose(so);
276 	return (error);
277 }
278 
279 int
280 nfs_boot_deladdress(ifp, procp, addr)
281 	struct ifnet *ifp;
282 	struct proc *procp;
283 	u_int32_t addr;
284 {
285 	struct socket *so;
286 	struct ifreq ireq;
287 	struct sockaddr_in *sin;
288 	int error;
289 
290 	/*
291 	 * Get a socket to use for various things in here.
292 	 * After this, use "goto out" to cleanup and return.
293 	 */
294 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
295 	if (error) {
296 		printf("deladdress: socreate, error=%d\n", error);
297 		return (error);
298 	}
299 
300 	memset(&ireq, 0, sizeof(ireq));
301 	memcpy(ireq.ifr_name, ifp->if_xname, IFNAMSIZ);
302 
303 	sin = (struct sockaddr_in *)&ireq.ifr_addr;
304 	sin->sin_len = sizeof(*sin);
305 	sin->sin_family = AF_INET;
306 	sin->sin_addr.s_addr = addr;
307 
308 	error = ifioctl(so, SIOCDIFADDR, (caddr_t)&ireq, procp);
309 	if (error) {
310 		printf("deladdress, error=%d\n", error);
311 		goto out;
312 	}
313 
314 out:
315 	soclose(so);
316 	return (error);
317 }
318 
319 int
320 nfs_boot_setrecvtimo(so)
321 	struct socket *so;
322 {
323 	struct mbuf *m;
324 	struct timeval *tv;
325 
326 	m = m_get(M_WAIT, MT_SOOPTS);
327 	tv = mtod(m, struct timeval *);
328 	m->m_len = sizeof(*tv);
329 	tv->tv_sec = 1;
330 	tv->tv_usec = 0;
331 	return (sosetopt(so, SOL_SOCKET, SO_RCVTIMEO, m));
332 }
333 
334 int
335 nfs_boot_enbroadcast(so)
336 	struct socket *so;
337 {
338 	struct mbuf *m;
339 	int32_t *on;
340 
341 	m = m_get(M_WAIT, MT_SOOPTS);
342 	on = mtod(m, int32_t *);
343 	m->m_len = sizeof(*on);
344 	*on = 1;
345 	return (sosetopt(so, SOL_SOCKET, SO_BROADCAST, m));
346 }
347 
348 int
349 nfs_boot_sobind_ipport(so, port)
350 	struct socket *so;
351 	u_int16_t port;
352 {
353 	struct mbuf *m;
354 	struct sockaddr_in *sin;
355 	int error;
356 
357 	m = m_getclr(M_WAIT, MT_SONAME);
358 	sin = mtod(m, struct sockaddr_in *);
359 	sin->sin_len = m->m_len = sizeof(*sin);
360 	sin->sin_family = AF_INET;
361 	sin->sin_addr.s_addr = INADDR_ANY;
362 	sin->sin_port = htons(port);
363 	error = sobind(so, m, curproc);
364 	m_freem(m);
365 	return (error);
366 }
367 
368 /*
369  * What is the longest we will wait before re-sending a request?
370  * Note this is also the frequency of "timeout" messages.
371  * The re-send loop counts up linearly to this maximum, so the
372  * first complaint will happen after (1+2+3+4+5)=15 seconds.
373  */
374 #define	MAX_RESEND_DELAY 5	/* seconds */
375 #define TOTAL_TIMEOUT   30	/* seconds */
376 
377 int
378 nfs_boot_sendrecv(so, nam, sndproc, snd, rcvproc, rcv, from_p, context)
379 	struct socket *so;
380 	struct mbuf *nam;
381 	int (*sndproc) __P((struct mbuf*, void*, int));
382 	struct mbuf *snd;
383 	int (*rcvproc) __P((struct mbuf*, void*));
384 	struct mbuf **rcv, **from_p;
385 	void *context;
386 {
387 	int error, rcvflg, timo, secs, waited;
388 	struct mbuf *m, *from;
389 	struct uio uio;
390 
391 	/* Free at end if not null. */
392 	from = NULL;
393 
394 	/*
395 	 * Send it, repeatedly, until a reply is received,
396 	 * but delay each re-send by an increasing amount.
397 	 * If the delay hits the maximum, start complaining.
398 	 */
399 	waited = timo = 0;
400 send_again:
401 	waited += timo;
402 	if (waited >= TOTAL_TIMEOUT)
403 		return (ETIMEDOUT);
404 
405 	/* Determine new timeout. */
406 	if (timo < MAX_RESEND_DELAY)
407 		timo++;
408 	else
409 		printf("nfs_boot: timeout...\n");
410 
411 	if (sndproc) {
412 		error = (*sndproc)(snd, context, waited);
413 		if (error)
414 			goto out;
415 	}
416 
417 	/* Send request (or re-send). */
418 	m = m_copypacket(snd, M_WAIT);
419 	if (m == NULL) {
420 		error = ENOBUFS;
421 		goto out;
422 	}
423 	error = (*so->so_send)(so, nam, NULL, m, NULL, 0);
424 	if (error) {
425 		printf("nfs_boot: sosend: %d\n", error);
426 		goto out;
427 	}
428 	m = NULL;
429 
430 	/*
431 	 * Wait for up to timo seconds for a reply.
432 	 * The socket receive timeout was set to 1 second.
433 	 */
434 
435 	secs = timo;
436 	for (;;) {
437 		if (from) {
438 			m_freem(from);
439 			from = NULL;
440 		}
441 		if (m) {
442 			m_freem(m);
443 			m = NULL;
444 		}
445 		uio.uio_resid = 1 << 16; /* ??? */
446 		rcvflg = 0;
447 		error = (*so->so_receive)(so, &from, &uio, &m, NULL, &rcvflg);
448 		if (error == EWOULDBLOCK) {
449 			if (--secs <= 0)
450 				goto send_again;
451 			continue;
452 		}
453 		if (error)
454 			goto out;
455 #ifdef DIAGNOSTIC
456 		if (!m || !(m->m_flags & M_PKTHDR)
457 		    || (1 << 16) - uio.uio_resid != m->m_pkthdr.len)
458 			panic("nfs_boot_sendrecv: return size");
459 #endif
460 
461 		if ((*rcvproc)(m, context))
462 			continue;
463 
464 		if (rcv)
465 			*rcv = m;
466 		else
467 			m_freem(m);
468 		if (from_p) {
469 			*from_p = from;
470 			from = NULL;
471 		}
472 		break;
473 	}
474 out:
475 	if (from) m_freem(from);
476 	return (error);
477 }
478 
479 /*
480  * Install a default route to the passed IP address.
481  */
482 static void
483 nfs_boot_defrt(gw_ip)
484 	struct in_addr *gw_ip;
485 {
486 	struct sockaddr dst, gw, mask;
487 	struct sockaddr_in *sin;
488 	int error;
489 
490 	/* Destination: (default) */
491 	memset((caddr_t)&dst, 0, sizeof(dst));
492 	dst.sa_len = sizeof(dst);
493 	dst.sa_family = AF_INET;
494 	/* Gateway: */
495 	memset((caddr_t)&gw, 0, sizeof(gw));
496 	sin = (struct sockaddr_in *)&gw;
497 	sin->sin_len = sizeof(*sin);
498 	sin->sin_family = AF_INET;
499 	sin->sin_addr.s_addr = gw_ip->s_addr;
500 	/* Mask: (zero length) */
501 	/* XXX - Just pass a null pointer? */
502 	memset(&mask, 0, sizeof(mask));
503 
504 	/* add, dest, gw, mask, flags, 0 */
505 	error = rtrequest(RTM_ADD, &dst, &gw, &mask,
506 			  (RTF_UP | RTF_GATEWAY | RTF_STATIC), NULL);
507 	if (error) {
508 		printf("nfs_boot: add route, error=%d\n", error);
509 		error = 0;
510 	}
511 }
512 
513 static int nfs_boot_delroute __P((struct radix_node *, void *));
514 static int
515 nfs_boot_delroute(rn, w)
516 	struct radix_node *rn;
517 	void *w;
518 {
519 	struct rtentry *rt = (struct rtentry *)rn;
520 	int error;
521 
522 	if (rt->rt_ifp != (struct ifnet *)w)
523 		return (0);
524 
525 	error = rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL);
526 	if (error)
527 		printf("nfs_boot: del route, error=%d\n", error);
528 
529 	return (0);
530 }
531 
532 void
533 nfs_boot_flushrt(ifp)
534 	struct ifnet *ifp;
535 {
536 
537 	rn_walktree(rt_tables[AF_INET], nfs_boot_delroute, ifp);
538 }
539 
540 /*
541  * Get an initial NFS file handle using Sun RPC/mountd.
542  * Separate function because we used to call it twice.
543  * (once for root and once for swap)
544  */
545 static int
546 nfs_boot_getfh(ndm)
547 	struct nfs_dlmount *ndm;	/* output */
548 {
549 	struct nfs_args *args;
550 	struct sockaddr_in *sin;
551 	char *pathname;
552 	int error;
553 	u_int16_t port;
554 
555 	args = &ndm->ndm_args;
556 
557 	/* Initialize mount args. */
558 	memset((caddr_t) args, 0, sizeof(*args));
559 	args->addr     = &ndm->ndm_saddr;
560 	args->addrlen  = args->addr->sa_len;
561 #ifdef NFS_BOOT_TCP
562 	args->sotype   = SOCK_STREAM;
563 #else
564 	args->sotype   = SOCK_DGRAM;
565 #endif
566 	args->fh       = ndm->ndm_fh;
567 	args->hostname = ndm->ndm_host;
568 	args->flags    = NFSMNT_NOCONN | NFSMNT_RESVPORT;
569 
570 #ifndef NFS_V2_ONLY
571 	args->flags    |= NFSMNT_NFSV3;
572 #endif
573 #ifdef	NFS_BOOT_OPTIONS
574 	args->flags    |= NFS_BOOT_OPTIONS;
575 #endif
576 #ifdef	NFS_BOOT_RWSIZE
577 	/*
578 	 * Reduce rsize,wsize for interfaces that consistently
579 	 * drop fragments of long UDP messages.  (i.e. wd8003).
580 	 * You can always change these later via remount.
581 	 */
582 	args->flags   |= NFSMNT_WSIZE | NFSMNT_RSIZE;
583 	args->wsize    = NFS_BOOT_RWSIZE;
584 	args->rsize    = NFS_BOOT_RWSIZE;
585 #endif
586 
587 	/*
588 	 * Find the pathname part of the "server:pathname"
589 	 * string left in ndm->ndm_host by nfs_boot_init.
590 	 */
591 	pathname = strchr(ndm->ndm_host, ':');
592 	if (pathname == 0) {
593 		printf("nfs_boot: getfh - no pathname\n");
594 		return (EIO);
595 	}
596 	pathname++;
597 
598 	/*
599 	 * Get file handle using RPC to mountd/mount
600 	 */
601 	sin = (struct sockaddr_in *)&ndm->ndm_saddr;
602 	error = md_mount(sin, pathname, args);
603 	if (error) {
604 		printf("nfs_boot: mountd `%s', error=%d\n",
605 		       ndm->ndm_host, error);
606 		return (error);
607 	}
608 
609 	/* Set port number for NFS use. */
610 	/* XXX: NFS port is always 2049, right? */
611 #ifdef NFS_BOOT_TCP
612 retry:
613 #endif
614 	error = krpc_portmap(sin, NFS_PROG,
615 		    (args->flags & NFSMNT_NFSV3) ? NFS_VER3 : NFS_VER2,
616 		    (args->sotype == SOCK_STREAM) ? IPPROTO_TCP : IPPROTO_UDP,
617 		    &port);
618 	if (port == htons(0))
619 		error = EIO;
620 	if (error) {
621 #ifdef NFS_BOOT_TCP
622 		if (args->sotype == SOCK_STREAM) {
623 			args->sotype = SOCK_DGRAM;
624 			goto retry;
625 		}
626 #endif
627 		printf("nfs_boot: portmap NFS, error=%d\n", error);
628 		return (error);
629 	}
630 	sin->sin_port = port;
631 	return (0);
632 }
633 
634 
635 /*
636  * RPC: mountd/mount
637  * Given a server pathname, get an NFS file handle.
638  * Also, sets sin->sin_port to the NFS service port.
639  */
640 static int
641 md_mount(mdsin, path, argp)
642 	struct sockaddr_in *mdsin;		/* mountd server address */
643 	char *path;
644 	struct nfs_args *argp;
645 {
646 	/* The RPC structures */
647 	struct rdata {
648 		u_int32_t errno;
649 		union {
650 			u_int8_t  v2fh[NFSX_V2FH];
651 			struct {
652 				u_int32_t fhlen;
653 				u_int8_t  fh[1];
654 			} v3fh;
655 		} fh;
656 	} *rdata;
657 	struct mbuf *m;
658 	u_int8_t *fh;
659 	int minlen, error;
660 	int mntver;
661 
662 	mntver = (argp->flags & NFSMNT_NFSV3) ? 3 : 2;
663 	do {
664 		/*
665 		 * Get port number for MOUNTD.
666 		 */
667 		error = krpc_portmap(mdsin, RPCPROG_MNT, mntver,
668 		                    IPPROTO_UDP, &mdsin->sin_port);
669 		if (error)
670 			continue;
671 
672 		/* This mbuf is consumed by krpc_call. */
673 		m = xdr_string_encode(path, strlen(path));
674 		if (m == NULL)
675 			return ENOMEM;
676 
677 		/* Do RPC to mountd. */
678 		error = krpc_call(mdsin, RPCPROG_MNT, mntver,
679 		                  RPCMNT_MOUNT, &m, NULL);
680 		if (error != EPROGMISMATCH)
681 			break;
682 		/* Try lower version of mountd. */
683 	} while (--mntver >= 1);
684 	if (error) {
685 		printf("nfs_boot: mountd error=%d\n", error);
686 		return error;
687 	}
688 	if (mntver != 3)
689 		argp->flags &= ~NFSMNT_NFSV3;
690 
691 	/* The reply might have only the errno. */
692 	if (m->m_len < 4)
693 		goto bad;
694 	/* Have at least errno, so check that. */
695 	rdata = mtod(m, struct rdata *);
696 	error = fxdr_unsigned(u_int32_t, rdata->errno);
697 	if (error)
698 		goto out;
699 
700 	/* Have errno==0, so the fh must be there. */
701 	if (mntver == 3) {
702 		argp->fhsize   = fxdr_unsigned(u_int32_t, rdata->fh.v3fh.fhlen);
703 		if (argp->fhsize > NFSX_V3FHMAX)
704 			goto bad;
705 		minlen = 2 * sizeof(u_int32_t) + argp->fhsize;
706 	} else {
707 		argp->fhsize   = NFSX_V2FH;
708 		minlen = sizeof(u_int32_t) + argp->fhsize;
709 	}
710 
711 	if (m->m_len < minlen) {
712 		m = m_pullup(m, minlen);
713 		if (m == NULL)
714 			return(EBADRPC);
715 		rdata = mtod(m, struct rdata *);
716 	}
717 
718 	fh = (mntver == 3) ?
719 		rdata->fh.v3fh.fh : rdata->fh.v2fh;
720 	memcpy(argp->fh, fh, argp->fhsize);
721 
722 	goto out;
723 
724 bad:
725 	error = EBADRPC;
726 
727 out:
728 	m_freem(m);
729 	return error;
730 }
731