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nfs_boot.c revision 1.53
      1 /*	$NetBSD: nfs_boot.c,v 1.53 2000/03/29 03:43:33 simonb 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_boot.h"
     45 
     46 #include <sys/param.h>
     47 #include <sys/systm.h>
     48 #include <sys/kernel.h>
     49 #include <sys/device.h>
     50 #include <sys/ioctl.h>
     51 #include <sys/proc.h>
     52 #include <sys/mount.h>
     53 #include <sys/mbuf.h>
     54 #include <sys/reboot.h>
     55 #include <sys/socket.h>
     56 #include <sys/socketvar.h>
     57 
     58 #include <net/if.h>
     59 #include <net/route.h>
     60 #include <net/if_ether.h>
     61 #include <net/if_types.h>
     62 
     63 #include <netinet/in.h>
     64 #include <netinet/if_inarp.h>
     65 
     66 #include <nfs/rpcv2.h>
     67 #include <nfs/krpc.h>
     68 #include <nfs/xdr_subs.h>
     69 
     70 #include <nfs/nfsproto.h>
     71 #include <nfs/nfs.h>
     72 #include <nfs/nfsmount.h>
     73 #include <nfs/nfsdiskless.h>
     74 
     75 /*
     76  * There are two implementations of NFS diskless boot.
     77  * One implementation uses BOOTP (RFC951, RFC1048),
     78  * the other uses Sun RPC/bootparams.  See the files:
     79  *    nfs_bootp.c:   BOOTP (RFC951, RFC1048)
     80  *    nfs_bootsun.c: Sun RPC/bootparams
     81  */
     82 #if defined(NFS_BOOT_BOOTP) || defined(NFS_BOOT_DHCP)
     83 int nfs_boot_rfc951 = 1; /* BOOTP enabled (default) */
     84 #endif
     85 #ifdef NFS_BOOT_BOOTPARAM
     86 int nfs_boot_bootparam = 1; /* BOOTPARAM enabled (default) */
     87 #endif
     88 
     89 /* mountd RPC */
     90 static int md_mount __P((struct sockaddr_in *mdsin, char *path,
     91 	struct nfs_args *argp));
     92 
     93 static void nfs_boot_defrt __P((struct in_addr *));
     94 static  int nfs_boot_getfh __P((struct nfs_dlmount *ndm));
     95 
     96 
     97 /*
     98  * Called with an empty nfs_diskless struct to be filled in.
     99  * Find an interface, determine its ip address (etc.) and
    100  * save all the boot parameters in the nfs_diskless struct.
    101  */
    102 int
    103 nfs_boot_init(nd, procp)
    104 	struct nfs_diskless *nd;
    105 	struct proc *procp;
    106 {
    107 	struct ifnet *ifp;
    108 	int error;
    109 
    110 	/*
    111 	 * Find the network interface.
    112 	 */
    113 	ifp = ifunit(root_device->dv_xname);
    114 	if (ifp == NULL) {
    115 		printf("nfs_boot: '%s' not found\n",
    116 		       root_device->dv_xname);
    117 		return (ENXIO);
    118 	}
    119 	nd->nd_ifp = ifp;
    120 
    121 	error = EADDRNOTAVAIL; /* ??? */
    122 #if defined(NFS_BOOT_BOOTP) || defined(NFS_BOOT_DHCP)
    123 	if (error && nfs_boot_rfc951) {
    124 #if defined(NFS_BOOT_DHCP)
    125 		printf("nfs_boot: trying DHCP/BOOTP\n");
    126 #else
    127 		printf("nfs_boot: trying BOOTP\n");
    128 #endif
    129 		error = nfs_bootdhcp(nd, procp);
    130 	}
    131 #endif
    132 #ifdef NFS_BOOT_BOOTPARAM
    133 	if (error && nfs_boot_bootparam) {
    134 		printf("nfs_boot: trying RARP (and RPC/bootparam)\n");
    135 		error = nfs_bootparam(nd, procp);
    136 	}
    137 #endif
    138 	if (error)
    139 		return (error);
    140 
    141 	/*
    142 	 * If the gateway address is set, add a default route.
    143 	 * (The mountd RPCs may go across a gateway.)
    144 	 */
    145 	if (nd->nd_gwip.s_addr)
    146 		nfs_boot_defrt(&nd->nd_gwip);
    147 
    148 	/*
    149 	 * Now fetch the NFS file handles as appropriate.
    150 	 */
    151 	error = nfs_boot_getfh(&nd->nd_root);
    152 
    153 	if (error)
    154 		nfs_boot_cleanup(nd, procp);
    155 
    156 	return (error);
    157 }
    158 
    159 void
    160 nfs_boot_cleanup(nd, procp)
    161 	struct nfs_diskless *nd;
    162 	struct proc *procp;
    163 {
    164 
    165 	nfs_boot_deladdress(nd->nd_ifp, procp, nd->nd_myip.s_addr);
    166 	nfs_boot_ifupdown(nd->nd_ifp, procp, 0);
    167 	nfs_boot_flushrt(nd->nd_ifp);
    168 }
    169 
    170 int
    171 nfs_boot_ifupdown(ifp, procp, up)
    172 	struct ifnet *ifp;
    173 	struct proc *procp;
    174 	int up;
    175 {
    176 	struct socket *so;
    177 	struct ifreq ireq;
    178 	int error;
    179 
    180 	memset(&ireq, 0, sizeof(ireq));
    181 	memcpy(ireq.ifr_name, ifp->if_xname, IFNAMSIZ);
    182 
    183 	/*
    184 	 * Get a socket to use for various things in here.
    185 	 * After this, use "goto out" to cleanup and return.
    186 	 */
    187 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
    188 	if (error) {
    189 		printf("ifupdown: socreate, error=%d\n", error);
    190 		return (error);
    191 	}
    192 
    193 	/*
    194 	 * Bring up the interface. (just set the "up" flag)
    195 	 * Get the old interface flags and or IFF_UP into them so
    196 	 * things like media selection flags are not clobbered.
    197 	 */
    198 	error = ifioctl(so, SIOCGIFFLAGS, (caddr_t)&ireq, procp);
    199 	if (error) {
    200 		printf("ifupdown: GIFFLAGS, error=%d\n", error);
    201 		goto out;
    202 	}
    203 	if (up)
    204 		ireq.ifr_flags |= IFF_UP;
    205 	else
    206 		ireq.ifr_flags &= ~IFF_UP;
    207 	error = ifioctl(so, SIOCSIFFLAGS, (caddr_t)&ireq, procp);
    208 	if (error) {
    209 		printf("ifupdown: SIFFLAGS, error=%d\n", error);
    210 		goto out;
    211 	}
    212 
    213 	if (up)
    214 		delay(3000000); /* give the link some time to get up */
    215 out:
    216 	soclose(so);
    217 	return (error);
    218 }
    219 
    220 int
    221 nfs_boot_setaddress(ifp, procp, addr, netmask, braddr)
    222 	struct ifnet *ifp;
    223 	struct proc *procp;
    224 	u_int32_t addr, netmask, braddr;
    225 {
    226 	struct socket *so;
    227 	struct ifaliasreq iareq;
    228 	struct sockaddr_in *sin;
    229 	int error;
    230 
    231 	/*
    232 	 * Get a socket to use for various things in here.
    233 	 * After this, use "goto out" to cleanup and return.
    234 	 */
    235 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
    236 	if (error) {
    237 		printf("setaddress: socreate, error=%d\n", error);
    238 		return (error);
    239 	}
    240 
    241 	memset(&iareq, 0, sizeof(iareq));
    242 	memcpy(iareq.ifra_name, ifp->if_xname, IFNAMSIZ);
    243 
    244 	/* Set the I/F address */
    245 	sin = (struct sockaddr_in *)&iareq.ifra_addr;
    246 	sin->sin_len = sizeof(*sin);
    247 	sin->sin_family = AF_INET;
    248 	sin->sin_addr.s_addr = addr;
    249 
    250 	/* Set the netmask */
    251 	if (netmask != INADDR_ANY) {
    252 		sin = (struct sockaddr_in *)&iareq.ifra_mask;
    253 		sin->sin_len = sizeof(*sin);
    254 		sin->sin_family = AF_INET;
    255 		sin->sin_addr.s_addr = netmask;
    256 	} /* else leave subnetmask unspecified (len=0) */
    257 
    258 	/* Set the broadcast addr. */
    259 	if (braddr != INADDR_ANY) {
    260 		sin = (struct sockaddr_in *)&iareq.ifra_broadaddr;
    261 		sin->sin_len = sizeof(*sin);
    262 		sin->sin_family = AF_INET;
    263 		sin->sin_addr.s_addr = braddr;
    264 	} /* else leave broadcast addr unspecified (len=0) */
    265 
    266 	error = ifioctl(so, SIOCAIFADDR, (caddr_t)&iareq, procp);
    267 	if (error) {
    268 		printf("setaddress, error=%d\n", error);
    269 		goto out;
    270 	}
    271 
    272 	delay(3000000); /* give the link some time to get up */
    273 out:
    274 	soclose(so);
    275 	return (error);
    276 }
    277 
    278 int
    279 nfs_boot_deladdress(ifp, procp, addr)
    280 	struct ifnet *ifp;
    281 	struct proc *procp;
    282 	u_int32_t addr;
    283 {
    284 	struct socket *so;
    285 	struct ifreq ireq;
    286 	struct sockaddr_in *sin;
    287 	int error;
    288 
    289 	/*
    290 	 * Get a socket to use for various things in here.
    291 	 * After this, use "goto out" to cleanup and return.
    292 	 */
    293 	error = socreate(AF_INET, &so, SOCK_DGRAM, 0);
    294 	if (error) {
    295 		printf("deladdress: socreate, error=%d\n", error);
    296 		return (error);
    297 	}
    298 
    299 	memset(&ireq, 0, sizeof(ireq));
    300 	memcpy(ireq.ifr_name, ifp->if_xname, IFNAMSIZ);
    301 
    302 	sin = (struct sockaddr_in *)&ireq.ifr_addr;
    303 	sin->sin_len = sizeof(*sin);
    304 	sin->sin_family = AF_INET;
    305 	sin->sin_addr.s_addr = addr;
    306 
    307 	error = ifioctl(so, SIOCDIFADDR, (caddr_t)&ireq, procp);
    308 	if (error) {
    309 		printf("deladdress, error=%d\n", error);
    310 		goto out;
    311 	}
    312 
    313 out:
    314 	soclose(so);
    315 	return (error);
    316 }
    317 
    318 int
    319 nfs_boot_setrecvtimo(so)
    320 	struct socket *so;
    321 {
    322 	struct mbuf *m;
    323 	struct timeval *tv;
    324 
    325 	m = m_get(M_WAIT, MT_SOOPTS);
    326 	tv = mtod(m, struct timeval *);
    327 	m->m_len = sizeof(*tv);
    328 	tv->tv_sec = 1;
    329 	tv->tv_usec = 0;
    330 	return (sosetopt(so, SOL_SOCKET, SO_RCVTIMEO, m));
    331 }
    332 
    333 int
    334 nfs_boot_enbroadcast(so)
    335 	struct socket *so;
    336 {
    337 	struct mbuf *m;
    338 	int32_t *on;
    339 
    340 	m = m_get(M_WAIT, MT_SOOPTS);
    341 	on = mtod(m, int32_t *);
    342 	m->m_len = sizeof(*on);
    343 	*on = 1;
    344 	return (sosetopt(so, SOL_SOCKET, SO_BROADCAST, m));
    345 }
    346 
    347 int
    348 nfs_boot_sobind_ipport(so, port)
    349 	struct socket *so;
    350 	u_int16_t port;
    351 {
    352 	struct mbuf *m;
    353 	struct sockaddr_in *sin;
    354 	int error;
    355 
    356 	m = m_getclr(M_WAIT, MT_SONAME);
    357 	sin = mtod(m, struct sockaddr_in *);
    358 	sin->sin_len = m->m_len = sizeof(*sin);
    359 	sin->sin_family = AF_INET;
    360 	sin->sin_addr.s_addr = INADDR_ANY;
    361 	sin->sin_port = htons(port);
    362 	error = sobind(so, m);
    363 	m_freem(m);
    364 	return (error);
    365 }
    366 
    367 /*
    368  * What is the longest we will wait before re-sending a request?
    369  * Note this is also the frequency of "timeout" messages.
    370  * The re-send loop counts up linearly to this maximum, so the
    371  * first complaint will happen after (1+2+3+4+5)=15 seconds.
    372  */
    373 #define	MAX_RESEND_DELAY 5	/* seconds */
    374 #define TOTAL_TIMEOUT   30	/* seconds */
    375 
    376 int
    377 nfs_boot_sendrecv(so, nam, sndproc, snd, rcvproc, rcv, from_p, context)
    378 	struct socket *so;
    379 	struct mbuf *nam;
    380 	int (*sndproc) __P((struct mbuf*, void*, int));
    381 	struct mbuf *snd;
    382 	int (*rcvproc) __P((struct mbuf*, void*));
    383 	struct mbuf **rcv, **from_p;
    384 	void *context;
    385 {
    386 	int error, rcvflg, timo, secs, waited;
    387 	struct mbuf *m, *from;
    388 	struct uio uio;
    389 
    390 	/* Free at end if not null. */
    391 	from = NULL;
    392 
    393 	/*
    394 	 * Send it, repeatedly, until a reply is received,
    395 	 * but delay each re-send by an increasing amount.
    396 	 * If the delay hits the maximum, start complaining.
    397 	 */
    398 	waited = timo = 0;
    399 send_again:
    400 	waited += timo;
    401 	if (waited >= TOTAL_TIMEOUT)
    402 		return (ETIMEDOUT);
    403 
    404 	/* Determine new timeout. */
    405 	if (timo < MAX_RESEND_DELAY)
    406 		timo++;
    407 	else
    408 		printf("nfs_boot: timeout...\n");
    409 
    410 	if (sndproc) {
    411 		error = (*sndproc)(snd, context, waited);
    412 		if (error)
    413 			goto out;
    414 	}
    415 
    416 	/* Send request (or re-send). */
    417 	m = m_copypacket(snd, M_WAIT);
    418 	if (m == NULL) {
    419 		error = ENOBUFS;
    420 		goto out;
    421 	}
    422 	error = (*so->so_send)(so, nam, NULL, m, NULL, 0);
    423 	if (error) {
    424 		printf("nfs_boot: sosend: %d\n", error);
    425 		goto out;
    426 	}
    427 	m = NULL;
    428 
    429 	/*
    430 	 * Wait for up to timo seconds for a reply.
    431 	 * The socket receive timeout was set to 1 second.
    432 	 */
    433 
    434 	secs = timo;
    435 	for (;;) {
    436 		if (from) {
    437 			m_freem(from);
    438 			from = NULL;
    439 		}
    440 		if (m) {
    441 			m_freem(m);
    442 			m = NULL;
    443 		}
    444 		uio.uio_resid = 1 << 16; /* ??? */
    445 		rcvflg = 0;
    446 		error = (*so->so_receive)(so, &from, &uio, &m, NULL, &rcvflg);
    447 		if (error == EWOULDBLOCK) {
    448 			if (--secs <= 0)
    449 				goto send_again;
    450 			continue;
    451 		}
    452 		if (error)
    453 			goto out;
    454 #ifdef DIAGNOSTIC
    455 		if (!m || !(m->m_flags & M_PKTHDR)
    456 		    || (1 << 16) - uio.uio_resid != m->m_pkthdr.len)
    457 			panic("nfs_boot_sendrecv: return size");
    458 #endif
    459 
    460 		if ((*rcvproc)(m, context))
    461 			continue;
    462 
    463 		if (rcv)
    464 			*rcv = m;
    465 		else
    466 			m_freem(m);
    467 		if (from_p) {
    468 			*from_p = from;
    469 			from = NULL;
    470 		}
    471 		break;
    472 	}
    473 out:
    474 	if (from) m_freem(from);
    475 	return (error);
    476 }
    477 
    478 /*
    479  * Install a default route to the passed IP address.
    480  */
    481 static void
    482 nfs_boot_defrt(gw_ip)
    483 	struct in_addr *gw_ip;
    484 {
    485 	struct sockaddr dst, gw, mask;
    486 	struct sockaddr_in *sin;
    487 	int error;
    488 
    489 	/* Destination: (default) */
    490 	memset((caddr_t)&dst, 0, sizeof(dst));
    491 	dst.sa_len = sizeof(dst);
    492 	dst.sa_family = AF_INET;
    493 	/* Gateway: */
    494 	memset((caddr_t)&gw, 0, sizeof(gw));
    495 	sin = (struct sockaddr_in *)&gw;
    496 	sin->sin_len = sizeof(*sin);
    497 	sin->sin_family = AF_INET;
    498 	sin->sin_addr.s_addr = gw_ip->s_addr;
    499 	/* Mask: (zero length) */
    500 	/* XXX - Just pass a null pointer? */
    501 	memset(&mask, 0, sizeof(mask));
    502 
    503 	/* add, dest, gw, mask, flags, 0 */
    504 	error = rtrequest(RTM_ADD, &dst, &gw, &mask,
    505 			  (RTF_UP | RTF_GATEWAY | RTF_STATIC), NULL);
    506 	if (error) {
    507 		printf("nfs_boot: add route, error=%d\n", error);
    508 		error = 0;
    509 	}
    510 }
    511 
    512 static int nfs_boot_delroute __P((struct radix_node *, void *));
    513 static int
    514 nfs_boot_delroute(rn, w)
    515 	struct radix_node *rn;
    516 	void *w;
    517 {
    518 	struct rtentry *rt = (struct rtentry *)rn;
    519 	int error;
    520 
    521 	if (rt->rt_ifp != (struct ifnet *)w)
    522 		return (0);
    523 
    524 	error = rtrequest(RTM_DELETE, rt_key(rt), NULL, rt_mask(rt), 0, NULL);
    525 	if (error)
    526 		printf("nfs_boot: del route, error=%d\n", error);
    527 
    528 	return (0);
    529 }
    530 
    531 void
    532 nfs_boot_flushrt(ifp)
    533 	struct ifnet *ifp;
    534 {
    535 
    536 	rn_walktree(rt_tables[AF_INET], nfs_boot_delroute, ifp);
    537 }
    538 
    539 /*
    540  * Get an initial NFS file handle using Sun RPC/mountd.
    541  * Separate function because we used to call it twice.
    542  * (once for root and once for swap)
    543  */
    544 static int
    545 nfs_boot_getfh(ndm)
    546 	struct nfs_dlmount *ndm;	/* output */
    547 {
    548 	struct nfs_args *args;
    549 	struct sockaddr_in *sin;
    550 	char *pathname;
    551 	int error;
    552 	u_int16_t port;
    553 
    554 	args = &ndm->ndm_args;
    555 
    556 	/* Initialize mount args. */
    557 	memset((caddr_t) args, 0, sizeof(*args));
    558 	args->addr     = &ndm->ndm_saddr;
    559 	args->addrlen  = args->addr->sa_len;
    560 #ifdef NFS_BOOT_TCP
    561 	args->sotype   = SOCK_STREAM;
    562 #else
    563 	args->sotype   = SOCK_DGRAM;
    564 #endif
    565 	args->fh       = ndm->ndm_fh;
    566 	args->hostname = ndm->ndm_host;
    567 	args->flags    = NFSMNT_NFSV3 | NFSMNT_NOCONN | NFSMNT_RESVPORT;
    568 
    569 #ifdef	NFS_BOOT_OPTIONS
    570 	args->flags    |= NFS_BOOT_OPTIONS;
    571 #endif
    572 #ifdef	NFS_BOOT_RWSIZE
    573 	/*
    574 	 * Reduce rsize,wsize for interfaces that consistently
    575 	 * drop fragments of long UDP messages.  (i.e. wd8003).
    576 	 * You can always change these later via remount.
    577 	 */
    578 	args->flags   |= NFSMNT_WSIZE | NFSMNT_RSIZE;
    579 	args->wsize    = NFS_BOOT_RWSIZE;
    580 	args->rsize    = NFS_BOOT_RWSIZE;
    581 #endif
    582 
    583 	/*
    584 	 * Find the pathname part of the "server:pathname"
    585 	 * string left in ndm->ndm_host by nfs_boot_init.
    586 	 */
    587 	pathname = strchr(ndm->ndm_host, ':');
    588 	if (pathname == 0) {
    589 		printf("nfs_boot: getfh - no pathname\n");
    590 		return (EIO);
    591 	}
    592 	pathname++;
    593 
    594 	/*
    595 	 * Get file handle using RPC to mountd/mount
    596 	 */
    597 	sin = (struct sockaddr_in *)&ndm->ndm_saddr;
    598 	error = md_mount(sin, pathname, args);
    599 	if (error) {
    600 		printf("nfs_boot: mountd `%s', error=%d\n",
    601 		       ndm->ndm_host, error);
    602 		return (error);
    603 	}
    604 
    605 	/* Set port number for NFS use. */
    606 	/* XXX: NFS port is always 2049, right? */
    607 #ifdef NFS_BOOT_TCP
    608 retry:
    609 #endif
    610 	error = krpc_portmap(sin, NFS_PROG,
    611 		    (args->flags & NFSMNT_NFSV3) ? NFS_VER3 : NFS_VER2,
    612 		    (args->sotype == SOCK_STREAM) ? IPPROTO_TCP : IPPROTO_UDP,
    613 		    &port);
    614 	if (port == htons(0))
    615 		error = EIO;
    616 	if (error) {
    617 #ifdef NFS_BOOT_TCP
    618 		if (args->sotype == SOCK_STREAM) {
    619 			args->sotype = SOCK_DGRAM;
    620 			goto retry;
    621 		}
    622 #endif
    623 		printf("nfs_boot: portmap NFS, error=%d\n", error);
    624 		return (error);
    625 	}
    626 	sin->sin_port = port;
    627 	return (0);
    628 }
    629 
    630 
    631 /*
    632  * RPC: mountd/mount
    633  * Given a server pathname, get an NFS file handle.
    634  * Also, sets sin->sin_port to the NFS service port.
    635  */
    636 static int
    637 md_mount(mdsin, path, argp)
    638 	struct sockaddr_in *mdsin;		/* mountd server address */
    639 	char *path;
    640 	struct nfs_args *argp;
    641 {
    642 	/* The RPC structures */
    643 	struct rdata {
    644 		u_int32_t errno;
    645 		union {
    646 			u_int8_t  v2fh[NFSX_V2FH];
    647 			struct {
    648 				u_int32_t fhlen;
    649 				u_int8_t  fh[1];
    650 			} v3fh;
    651 		} fh;
    652 	} *rdata;
    653 	struct mbuf *m;
    654 	u_int8_t *fh;
    655 	int minlen, error;
    656 	int mntver;
    657 
    658 	mntver = (argp->flags & NFSMNT_NFSV3) ? 3 : 2;
    659 	do {
    660 		/*
    661 		 * Get port number for MOUNTD.
    662 		 */
    663 		error = krpc_portmap(mdsin, RPCPROG_MNT, mntver,
    664 		                    IPPROTO_UDP, &mdsin->sin_port);
    665 		if (error)
    666 			continue;
    667 
    668 		/* This mbuf is consumed by krpc_call. */
    669 		m = xdr_string_encode(path, strlen(path));
    670 		if (m == NULL)
    671 			return ENOMEM;
    672 
    673 		/* Do RPC to mountd. */
    674 		error = krpc_call(mdsin, RPCPROG_MNT, mntver,
    675 		                  RPCMNT_MOUNT, &m, NULL);
    676 		if (error != EPROGMISMATCH)
    677 			break;
    678 		/* Try lower version of mountd. */
    679 	} while (--mntver >= 1);
    680 	if (error) {
    681 		printf("nfs_boot: mountd error=%d\n", error);
    682 		return error;
    683 	}
    684 	if (mntver != 3)
    685 		argp->flags &= ~NFSMNT_NFSV3;
    686 
    687 	/* The reply might have only the errno. */
    688 	if (m->m_len < 4)
    689 		goto bad;
    690 	/* Have at least errno, so check that. */
    691 	rdata = mtod(m, struct rdata *);
    692 	error = fxdr_unsigned(u_int32_t, rdata->errno);
    693 	if (error)
    694 		goto out;
    695 
    696 	/* Have errno==0, so the fh must be there. */
    697 	if (mntver == 3) {
    698 		argp->fhsize   = fxdr_unsigned(u_int32_t, rdata->fh.v3fh.fhlen);
    699 		if (argp->fhsize > NFSX_V3FHMAX)
    700 			goto bad;
    701 		minlen = 2 * sizeof(u_int32_t) + argp->fhsize;
    702 	} else {
    703 		argp->fhsize   = NFSX_V2FH;
    704 		minlen = sizeof(u_int32_t) + argp->fhsize;
    705 	}
    706 
    707 	if (m->m_len < minlen) {
    708 		m = m_pullup(m, minlen);
    709 		if (m == NULL)
    710 			return(EBADRPC);
    711 		rdata = mtod(m, struct rdata *);
    712 	}
    713 
    714 	fh = (mntver == 3) ?
    715 		rdata->fh.v3fh.fh : rdata->fh.v2fh;
    716 	memcpy(argp->fh, fh, argp->fhsize);
    717 
    718 	goto out;
    719 
    720 bad:
    721 	error = EBADRPC;
    722 
    723 out:
    724 	m_freem(m);
    725 	return error;
    726 }
    727