xnu-517.7.7.tar.gz

[apple/xnu.git] / bsd / nfs / nfs_boot.c

/*
 * Copyright (c) 2000-2002 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * The contents of this file constitute Original Code as defined in and
 * are subject to the Apple Public Source License Version 1.1 (the
 * "License").  You may not use this file except in compliance with the
 * License.  Please obtain a copy of the License at
 * http://www.apple.com/publicsource and read it before using this file.
 * 
 * This Original Code and all software distributed under the License are
 * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
 * License for the specific language governing rights and limitations
 * under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/* Copyright (c) 1995, 1997 NeXT Computer, Inc. All Rights Reserved */
/*
 * Copyright (c) 1994 Adam Glass, Gordon Ross
 * All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by the University of
 *      California, Lawrence Berkeley Laboratory and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *  History:
 *  14-March-97 Dieter Siegmund (dieter@next.com)
 *      - Use BOOTP instead of RARP to get the IP address at boot time
 *
 *  23-May-97  Umesh Vaishampayan  (umeshv@apple.com)
 *      - Added the ability to mount "/private" separately.
 *
 *  30-May-97   Dieter Siegmund (dieter@next.com)
 *      - Clear out the ireq structure before using it to prevent
 *        our sending using a bogus source IP address, we should use
 *        an IP address of all zeroes
 *      - Right after BOOTP, get the correct netmask using AUTONETMASK
 *  18-Jul-97   Dieter Siegmund (dieter@apple.com)
 *      - we can't restrict the netmask until we have a default route,
 *        removed AUTONETMASK call (ifdef'd out)
 *  5-Aug-97    Dieter Siegmund (dieter@apple.com)
 *      - use the default route from the bpwhoami call, enabled autonetmask
 *        again
 *  19-Feb-1999 Dieter Siegmund (dieter@apple.com)
 *      - use new BOOTP routine to get the subnet mask and router
 *        and stop using SIOCAUTOADDR
 *      - don't bother mounting private separately if it's not
 *        specified or not required because they are substrings of
 *        one another ie. root=host:/A and private=host:/A/private
 *      - allow the root path to be specified in the boot variable
 *        "rp" (AKA "rootpath")
 *  19-Jul-1999 Dieter Siegmund (dieter@apple.com)
 *      - replaced big automatic arrays with MALLOC'd data
 */

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/ioctl.h>
#include <sys/proc.h>
#include <sys/mount.h>
#include <sys/mbuf.h>

#include <sys/malloc.h>
#include <sys/socket.h>
#include <sys/reboot.h>

#include <net/if.h>
#include <net/if_dl.h>
#include <net/if_types.h>
#include <net/route.h>

#include <netinet/in.h>
#include <netinet/if_ether.h>

#include <nfs/rpcv2.h>
#include <nfs/nfsproto.h>
#include <nfs/nfs.h>
#include <nfs/nfsdiskless.h>
#include <nfs/krpc.h>

#include <pexpert/pexpert.h>

#include "ether.h"

#include <libkern/libkern.h>

extern char *strchr(const char *str, int ch);

#if NETHER == 0

int nfs_boot_init(nd, procp)
        struct nfs_diskless *nd;
        struct proc *procp;
{
        panic("nfs_boot_init: no ether");
}

int nfs_boot_getfh(nd, procp, v3)
        struct nfs_diskless *nd;
        struct proc *procp;
        int v3;
{
        panic("nfs_boot_getfh: no ether");
}

#else /* NETHER */

/*
 * Support for NFS diskless booting, specifically getting information
 * about where to boot from, what pathnames, etc.
 *
 * This implememtation uses RARP and the bootparam RPC.
 * We are forced to implement RPC anyway (to get file handles)
 * so we might as well take advantage of it for bootparam too.
 *
 * The diskless boot sequence goes as follows:
 * (1) Use RARP to get our interface address
 * (2) Use RPC/bootparam/whoami to get our hostname,
 *     our IP address, and the server's IP address.
 * (3) Use RPC/bootparam/getfile to get the root path
 * (4) Use RPC/mountd to get the root file handle
 * (5) Use RPC/bootparam/getfile to get the swap path
 * (6) Use RPC/mountd to get the swap file handle
 *
 * (This happens to be the way Sun does it too.)
 */

/* bootparam RPC */
static int bp_whoami __P((struct sockaddr_in *bpsin,
        struct in_addr *my_ip, struct in_addr *gw_ip));
static int bp_getfile __P((struct sockaddr_in *bpsin, char *key,
        struct sockaddr_in *mdsin, char *servname, char *path));

/* mountd RPC */
static int md_mount __P((struct sockaddr_in *mdsin, char *path, int v3,
        u_char *fhp, u_long *fhlenp));

/* other helpers */
static int get_file_handle __P((struct nfs_dlmount *ndmntp));


#define IP_FORMAT       "%d.%d.%d.%d"
#define IP_CH(ip)       ((u_char *)ip)
#define IP_LIST(ip)     IP_CH(ip)[0],IP_CH(ip)[1],IP_CH(ip)[2],IP_CH(ip)[3]

extern boolean_t
netboot_iaddr(struct in_addr * iaddr_p);

extern boolean_t
netboot_rootpath(struct in_addr * server_ip,
                 char * name, int name_len, 
                 char * path, int path_len);

/*
 * Called with an empty nfs_diskless struct to be filled in.
 */
int
nfs_boot_init(nd, procp)
        struct nfs_diskless *nd;
        struct proc *procp;
{
        struct sockaddr_in      bp_sin;
        boolean_t               do_bpwhoami = TRUE;
        boolean_t               do_bpgetfile = TRUE;
        int                     error = 0;
        struct in_addr          my_ip;
        struct sockaddr_in *    sin_p;

        /* by this point, networking must already have been configured */
        if (netboot_iaddr(&my_ip) == FALSE) {
            printf("nfs_boot: networking is not initialized\n");
            error = ENXIO;
            goto failed_noswitch;
        }

        /* get the root path information */
        MALLOC_ZONE(nd->nd_root.ndm_path, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
        sin_p = &nd->nd_root.ndm_saddr;
        bzero((caddr_t)sin_p, sizeof(*sin_p));
        sin_p->sin_len = sizeof(*sin_p);
        sin_p->sin_family = AF_INET;
        if (netboot_rootpath(&sin_p->sin_addr, nd->nd_root.ndm_host, 
                             sizeof(nd->nd_root.ndm_host),
                             nd->nd_root.ndm_path, MAXPATHLEN) == TRUE) {
            do_bpgetfile = FALSE;
            do_bpwhoami = FALSE;
        }
        nd->nd_private.ndm_saddr.sin_addr.s_addr = 0;

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);

        if (do_bpwhoami) {
                struct in_addr router;
                /*
                 * Get client name and gateway address.
                 * RPC: bootparam/whoami
                 * Use the old broadcast address for the WHOAMI
                 * call because we do not yet know our netmask.
                 * The server address returned by the WHOAMI call
                 * is used for all subsequent booptaram RPCs.
                 */
                bzero((caddr_t)&bp_sin, sizeof(bp_sin));
                bp_sin.sin_len = sizeof(bp_sin);
                bp_sin.sin_family = AF_INET;
                bp_sin.sin_addr.s_addr = INADDR_BROADCAST;
                hostnamelen = MAXHOSTNAMELEN;
                router.s_addr = 0;
                error = bp_whoami(&bp_sin, &my_ip, &router);
                if (error) {
                        printf("nfs_boot: bootparam whoami, error=%d", error);
                        goto failed;
                }
                printf("nfs_boot: BOOTPARAMS server " IP_FORMAT "\n", 
                       IP_LIST(&bp_sin.sin_addr));
                printf("nfs_boot: hostname %s\n", hostname);
        }
        if (do_bpgetfile) {
                error = bp_getfile(&bp_sin, "root", &nd->nd_root.ndm_saddr,
                                   nd->nd_root.ndm_host, nd->nd_root.ndm_path);
                if (error) {
                        printf("nfs_boot: bootparam get root: %d\n", error);
                        goto failed;
                }
        }

#if !defined(NO_MOUNT_PRIVATE) 
        if (do_bpgetfile) { /* get private path */
                MALLOC_ZONE(nd->nd_private.ndm_path, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
                error = bp_getfile(&bp_sin, "private", 
                                   &nd->nd_private.ndm_saddr,
                                   nd->nd_private.ndm_host,
                                   nd->nd_private.ndm_path);
                if (!error) {
                        char * check_path = NULL;
                        
                        MALLOC_ZONE(check_path, char *, MAXPATHLEN, M_NAMEI, M_WAITOK);
                        snprintf(check_path, MAXPATHLEN, "%s/private", nd->nd_root.ndm_path);
                        if ((nd->nd_root.ndm_saddr.sin_addr.s_addr 
                             == nd->nd_private.ndm_saddr.sin_addr.s_addr)
                            && (strcmp(check_path, nd->nd_private.ndm_path) == 0)) {
                                /* private path is prefix of root path, don't mount */
                                nd->nd_private.ndm_saddr.sin_addr.s_addr = 0;
                        }
                        FREE_ZONE(check_path, MAXPATHLEN, M_NAMEI);
                }
                else { 
                        /* private key not defined, don't mount */
                        nd->nd_private.ndm_saddr.sin_addr.s_addr = 0;
                }
        }
        else {
                error = 0;
        }
#endif /* NO_MOUNT_PRIVATE */
failed:
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
failed_noswitch:
        return (error);
}

/*
 * Called with a partially initialized nfs_diskless struct
 * with file handles to be filled in.
 */
int
nfs_boot_getfh(nd, procp, v3)
        struct nfs_diskless *nd;
        struct proc *procp;
        int v3;
{
        int error = 0;

        thread_funnel_switch(KERNEL_FUNNEL, NETWORK_FUNNEL);
        
        nd->nd_root.ndm_nfsv3 = v3;
        error = get_file_handle(&nd->nd_root);
        if (error) {
                printf("nfs_boot: get_file_handle(v%d) root failed, %d\n",
                        v3 ? 3 : 2, error);
                goto failed;
        }

#if !defined(NO_MOUNT_PRIVATE) 
        if (nd->nd_private.ndm_saddr.sin_addr.s_addr) {
                /* get private file handle */
                nd->nd_private.ndm_nfsv3 = v3;
                error = get_file_handle(&nd->nd_private);
                if (error) {
                        printf("nfs_boot: get_file_handle(v%d) private failed, %d\n",
                                v3 ? 3 : 2, error);
                        goto failed;
                }
        }
#endif /* NO_MOUNT_PRIVATE */
 failed:
        thread_funnel_switch(NETWORK_FUNNEL, KERNEL_FUNNEL);
        return (error);
}

static int
get_file_handle(ndmntp)
        struct nfs_dlmount *ndmntp;
{
        char *sp, *dp, *endp;
        int error;

        /*
         * Get file handle for "key" (root or swap)
         * using RPC to mountd/mount
         */
        error = md_mount(&ndmntp->ndm_saddr, ndmntp->ndm_path, ndmntp->ndm_nfsv3,
                        ndmntp->ndm_fh, &ndmntp->ndm_fhlen);
        if (error)
                return (error);

        /* Construct remote path (for getmntinfo(3)) */
        dp = ndmntp->ndm_host;
        endp = dp + MNAMELEN - 1;
        dp += strlen(dp);
        *dp++ = ':';
        for (sp = ndmntp->ndm_path; *sp && dp < endp;)
                *dp++ = *sp++;
        *dp = '\0';
        return (0);

}


/*
 * Get an mbuf with the given length, and
 * initialize the pkthdr length field.
 */
static struct mbuf *
m_get_len(int msg_len)
{
        struct mbuf *m;
        m = m_gethdr(M_WAIT, MT_DATA);
        if (m == NULL)
                return NULL;
        if (msg_len > MHLEN) {
                if (msg_len > MCLBYTES)
                        panic("nfs_boot: msg_len > MCLBYTES");
                MCLGET(m, M_WAIT);
                if (m == NULL)
                        return NULL;
        }
        m->m_len = msg_len;
        m->m_pkthdr.len = m->m_len;
        return (m);
}


/*
 * String representation for RPC.
 */
struct rpc_string {
        u_long len;             /* length without null or padding */
        u_char data[4]; /* data (longer, of course) */
    /* data is padded to a long-word boundary */
};
/* Compute space used given string length. */
#define RPC_STR_SIZE(slen) (4 + ((slen + 3) & ~3))

/*
 * Inet address in RPC messages
 * (Note, really four longs, NOT chars.  Blech.)
 */
struct bp_inaddr {
        u_long  atype;
        long    addr[4];
};


/*
 * RPC: bootparam/whoami
 * Given client IP address, get:
 *      client name     (hostname)
 *      domain name (domainname)
 *      gateway address
 *
 * The hostname and domainname are set here for convenience.
 *
 * Note - bpsin is initialized to the broadcast address,
 * and will be replaced with the bootparam server address
 * after this call is complete.  Have to use PMAP_PROC_CALL
 * to make sure we get responses only from a servers that
 * know about us (don't want to broadcast a getport call).
 */
static int
bp_whoami(bpsin, my_ip, gw_ip)
        struct sockaddr_in *bpsin;
        struct in_addr *my_ip;
        struct in_addr *gw_ip;
{
        /* RPC structures for PMAPPROC_CALLIT */
        struct whoami_call {
                u_long call_prog;
                u_long call_vers;
                u_long call_proc;
                u_long call_arglen;
                struct bp_inaddr call_ia;
        } *call;

        struct rpc_string *str;
        struct bp_inaddr *bia;
        struct mbuf *m;
        struct sockaddr_in *sin;
        int error, msg_len;
        int cn_len, dn_len;
        u_char *p;
        long *lp;

        /*
         * Get message buffer of sufficient size.
         */
        msg_len = sizeof(*call);
        m = m_get_len(msg_len);
        if (m == NULL)
                return ENOBUFS;

        /*
         * Build request message for PMAPPROC_CALLIT.
         */
        call = mtod(m, struct whoami_call *);
        call->call_prog = htonl(BOOTPARAM_PROG);
        call->call_vers = htonl(BOOTPARAM_VERS);
        call->call_proc = htonl(BOOTPARAM_WHOAMI);
        call->call_arglen = htonl(sizeof(struct bp_inaddr));

        /* client IP address */
        call->call_ia.atype = htonl(1);
        p = (u_char*)my_ip;
        lp = call->call_ia.addr;
        *lp++ = htonl(*p);      p++;
        *lp++ = htonl(*p);      p++;
        *lp++ = htonl(*p);      p++;
        *lp++ = htonl(*p);      p++;

        /* RPC: portmap/callit */
        bpsin->sin_port = htons(PMAPPORT);

        error = krpc_call(bpsin, PMAPPROG, PMAPVERS,
                        PMAPPROC_CALLIT, &m, &sin);
        if (error)
                return error;

        /*
         * Parse result message.
         */
        msg_len = m->m_len;
        lp = mtod(m, long *);

        /* bootparam server port (also grab from address). */
        if (msg_len < sizeof(*lp))
                goto bad;
        msg_len -= sizeof(*lp);
        bpsin->sin_port = htons((short)ntohl(*lp++));
        bpsin->sin_addr.s_addr = sin->sin_addr.s_addr;

        /* length of encapsulated results */
        if (msg_len < (ntohl(*lp) + sizeof(*lp)))
                goto bad;
        msg_len = ntohl(*lp++);
        p = (char*)lp;

        /* client name */
        if (msg_len < sizeof(*str))
                goto bad;
        str = (struct rpc_string *)p;
        cn_len = ntohl(str->len);
        if (msg_len < cn_len)
                goto bad;
        if (cn_len >= MAXHOSTNAMELEN)
                goto bad;
        bcopy(str->data, hostname, cn_len);
        hostname[cn_len] = '\0';
        hostnamelen = cn_len;
        p += RPC_STR_SIZE(cn_len);
        msg_len -= RPC_STR_SIZE(cn_len);

        /* domain name */
        if (msg_len < sizeof(*str))
                goto bad;
        str = (struct rpc_string *)p;
        dn_len = ntohl(str->len);
        if (msg_len < dn_len)
                goto bad;
        if (dn_len >= MAXHOSTNAMELEN)
                goto bad;
        bcopy(str->data, domainname, dn_len);
        domainname[dn_len] = '\0';
        domainnamelen = dn_len;
        p += RPC_STR_SIZE(dn_len);
        msg_len -= RPC_STR_SIZE(dn_len);

        /* gateway address */
        if (msg_len < sizeof(*bia))
                goto bad;
        bia = (struct bp_inaddr *)p;
        if (bia->atype != htonl(1))
                goto bad;
        p = (u_char*)gw_ip;
        *p++ = ntohl(bia->addr[0]);
        *p++ = ntohl(bia->addr[1]);
        *p++ = ntohl(bia->addr[2]);
        *p++ = ntohl(bia->addr[3]);
        goto out;

bad:
        printf("nfs_boot: bootparam_whoami: bad reply\n");
        error = EBADRPC;

out:
        if (sin)
            FREE(sin, M_SONAME);

        m_freem(m);
        return(error);
}


/*
 * RPC: bootparam/getfile
 * Given client name and file "key", get:
 *      server name
 *      server IP address
 *      server pathname
 */
static int
bp_getfile(bpsin, key, md_sin, serv_name, pathname)
        struct sockaddr_in *bpsin;
        char *key;
        struct sockaddr_in *md_sin;
        char *serv_name;
        char *pathname;
{
        struct rpc_string *str;
        struct mbuf *m;
        struct bp_inaddr *bia;
        struct sockaddr_in *sin;
        u_char *p, *q;
        int error, msg_len;
        int cn_len, key_len, sn_len, path_len;

        /*
         * Get message buffer of sufficient size.
         */
        cn_len = hostnamelen;
        key_len = strlen(key);
        msg_len = 0;
        msg_len += RPC_STR_SIZE(cn_len);
        msg_len += RPC_STR_SIZE(key_len);
        m = m_get_len(msg_len);
        if (m == NULL)
                return ENOBUFS;

        /*
         * Build request message.
         */
        p = mtod(m, u_char *);
        bzero(p, msg_len);
        /* client name (hostname) */
        str = (struct rpc_string *)p;
        str->len = htonl(cn_len);
        bcopy(hostname, str->data, cn_len);
        p += RPC_STR_SIZE(cn_len);
        /* key name (root or swap) */
        str = (struct rpc_string *)p;
        str->len = htonl(key_len);
        bcopy(key, str->data, key_len);

        /* RPC: bootparam/getfile */
        error = krpc_call(bpsin, BOOTPARAM_PROG, BOOTPARAM_VERS,
                        BOOTPARAM_GETFILE, &m, NULL);
        if (error)
                return error;

        /*
         * Parse result message.
         */
        p = mtod(m, u_char *);
        msg_len = m->m_len;

        /* server name */
        if (msg_len < sizeof(*str))
                goto bad;
        str = (struct rpc_string *)p;
        sn_len = ntohl(str->len);
        if (msg_len < sn_len)
                goto bad;
        if (sn_len >= MNAMELEN)
                goto bad;
        bcopy(str->data, serv_name, sn_len);
        serv_name[sn_len] = '\0';
        p += RPC_STR_SIZE(sn_len);
        msg_len -= RPC_STR_SIZE(sn_len);

        /* server IP address (mountd) */
        if (msg_len < sizeof(*bia))
                goto bad;
        bia = (struct bp_inaddr *)p;
        if (bia->atype != htonl(1))
                goto bad;
        sin = md_sin;
        bzero((caddr_t)sin, sizeof(*sin));
        sin->sin_len = sizeof(*sin);
        sin->sin_family = AF_INET;
        q = (u_char*) &sin->sin_addr;
        *q++ = ntohl(bia->addr[0]);
        *q++ = ntohl(bia->addr[1]);
        *q++ = ntohl(bia->addr[2]);
        *q++ = ntohl(bia->addr[3]);
        p += sizeof(*bia);
        msg_len -= sizeof(*bia);

        /* server pathname */
        if (msg_len < sizeof(*str))
                goto bad;
        str = (struct rpc_string *)p;
        path_len = ntohl(str->len);
        if (msg_len < path_len)
                goto bad;
        if (path_len >= MAXPATHLEN)
                goto bad;
        bcopy(str->data, pathname, path_len);
        pathname[path_len] = '\0';
        goto out;

bad:
        printf("nfs_boot: bootparam_getfile: bad reply\n");
        error = EBADRPC;

out:
        m_freem(m);
        return(0);
}


/*
 * RPC: mountd/mount
 * Given a server pathname, get an NFS file handle.
 * Also, sets sin->sin_port to the NFS service port.
 */
static int
md_mount(mdsin, path, v3, fhp, fhlenp)
        struct sockaddr_in *mdsin;              /* mountd server address */
        char *path;
        int v3;
        u_char *fhp;
        u_long *fhlenp;
{
        /* The RPC structures */
        struct rpc_string *str;
        struct rdata {
                u_long  errno;
                u_char  data[NFSX_V3FHMAX + sizeof(u_long)];
        } *rdata;
        struct mbuf *m;
        int error, mlen, slen;
        int mntversion = v3 ? RPCMNT_VER3 : RPCMNT_VER1;

        /* Get port number for MOUNTD. */
        error = krpc_portmap(mdsin, RPCPROG_MNT, mntversion,
                                                 &mdsin->sin_port);
        if (error) return error;

        slen = strlen(path);
        mlen = RPC_STR_SIZE(slen);

        m = m_get_len(mlen);
        if (m == NULL)
                return ENOBUFS;
        str = mtod(m, struct rpc_string *);
        str->len = htonl(slen);
        bcopy(path, str->data, slen);

        /* Do RPC to mountd. */
        error = krpc_call(mdsin, RPCPROG_MNT, mntversion,
                        RPCMNT_MOUNT, &m, NULL);
        if (error)
                return error;   /* message already freed */

        /*
         * the reply must be long enough to hold the errno plus either of:
         * + a v2 filehandle
         * + a v3 filehandle length + a v3 filehandle
         */
        mlen = m->m_len;
        if (mlen < sizeof(u_long))
                goto bad;
        rdata = mtod(m, struct rdata *);
        error = ntohl(rdata->errno);
        if (error)
                goto out;
        if (v3) {
                u_long fhlen;
                u_char *fh;
                if (mlen < sizeof(u_long)*2)
                        goto bad;
                fhlen = ntohl(*(u_long*)rdata->data);
                fh = rdata->data + sizeof(u_long);
                if (mlen < (sizeof(u_long)*2 + fhlen))
                        goto bad;
                bcopy(fh, fhp, fhlen);
                *fhlenp = fhlen;
        } else {
                if (mlen < (sizeof(u_long) + NFSX_V2FH))
                        goto bad;
                bcopy(rdata->data, fhp, NFSX_V2FH);
                *fhlenp = NFSX_V2FH;
        }

        /* Set port number for NFS use. */
        error = krpc_portmap(mdsin, NFS_PROG, v3 ? NFS_VER3 : NFS_VER2,
                                                 &mdsin->sin_port);
        goto out;

bad:
        error = EBADRPC;

out:
        m_freem(m);
        return error;
}

#endif /* NETHER */