xdr_rec.c

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/*
 * Copyright (c) 2009, Sun Microsystems, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - 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.
 * - Neither the name of Sun Microsystems, Inc. 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 COPYRIGHT HOLDERS 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 COPYRIGHT HOLDER 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.
 */

//#include <sys/cdefs.h>
//#include <sys/cdefs.h>

/*
 * xdr_rec.c, Implements TCP/IP based XDR streams with a "record marking"
 * layer above tcp (for rpc's use).
 *
 * Copyright (C) 1984, Sun Microsystems, Inc.
 *
 * These routines interface XDRSTREAMS to a tcp/ip connection.
 * There is a record marking layer between the xdr stream
 * and the tcp transport level.  A record is composed on one or more
 * record fragments.  A record fragment is a thirty-two bit header followed
 * by n bytes of data, where n is contained in the header.  The header
 * is represented as a htonl(u_long).  Thegh order bit encodes
 * whether or not the fragment is the last fragment of the record
 * (1 => fragment is last, 0 => more fragments to follow. 
 * The other 31 bits encode the byte length of the fragment.
 */

/* NFSv4.1 client for Windows
 * Copyright © 2012 The Regents of the University of Michigan
 *
 * Olga Kornievskaia <aglo@umich.edu>
 * Casey Bodley <cbodley@umich.edu>
 *
 * This library is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at
 * your option) any later version.
 *
 * This library is distributed in the hope that it will be useful, but
 * without any warranty; without even the implied warranty of merchantability
 * or fitness for a particular purpose.  See the GNU Lesser General Public
 * License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA
 */

#include <wintirpc.h>
#include <io.h>
#include <sys/types.h>

//#include <netinet/in.h>

//#include <err.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <rpc/types.h>
#include <rpc/xdr.h>
#include <rpc/auth.h>
#include <rpc/svc_auth.h>
#include <rpc/svc.h>
#include <rpc/clnt.h>
#include <stddef.h>
#include "rpc_com.h"
//#include <unistd.h>
static bool_t   xdrrec_getlong(XDR *, long *);
static bool_t   xdrrec_putlong(XDR *, const long *);
static bool_t   xdrrec_getbytes(XDR *, char *, u_int);

static bool_t   xdrrec_putbytes(XDR *, const char *, u_int);
static u_int    xdrrec_getpos(XDR *);
static bool_t   xdrrec_setpos(XDR *, u_int);
static int32_t *xdrrec_inline(XDR *, u_int);
static void xdrrec_destroy(XDR *);

static const struct  xdr_ops xdrrec_ops = {
    xdrrec_getlong,
    xdrrec_putlong,
    xdrrec_getbytes,
    xdrrec_putbytes,
    xdrrec_getpos,
    xdrrec_setpos,
    xdrrec_inline,
    xdrrec_destroy
};

/*
 * A record is composed of one or more record fragments.
 * A record fragment is a four-byte header followed by zero to
 * 2**32-1 bytes.  The header is treated as a long unsigned and is
 * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
 * are a byte count of the fragment.  The highest order bit is a boolean:
 * 1 => this fragment is the last fragment of the record,
 * 0 => this fragment is followed by more fragment(s).
 *
 * The fragment/record machinery is not general;  it is constructed to
 * meet the needs of xdr and rpc based on tcp.
 */

#define LAST_FRAG ((u_int32_t)(1 << 31))

typedef struct rec_strm {
    char *tcp_handle;
    /*
     * out-goung bits
     */
    int (*writeit)(void *, void *, int);
    char *out_base; /* output buffer (points to frag header) */
    char *out_finger;   /* next output position */
    char *out_boundry;  /* data cannot up to this address */
    u_int32_t *frag_header; /* beginning of curren fragment */
    bool_t frag_sent;   /* true if buffer sent in middle of record */
    /*
     * in-coming bits
     */
    int (*readit)(void *, void *, int);
    u_long in_size; /* fixed size of the input buffer */
    char *in_base;
    char *in_finger;    /* location of next byte to be had */
    char *in_boundry;   /* can read up to this location */
    u_int fbtbc;        /* fragment bytes to be consumed */
    bool_t last_frag;
    u_int sendsize;
    u_int recvsize;

    bool_t nonblock;
    bool_t in_haveheader;
    u_int32_t in_header;
    char *in_hdrp;
    u_int in_hdrlen;
    u_int in_reclen;
    u_int in_received;
    u_int in_maxrec;
} RECSTREAM;

static u_int    fix_buf_size(u_int);
static bool_t   flush_out(RECSTREAM *, bool_t);
static bool_t   fill_input_buf(RECSTREAM *);
static bool_t   get_input_bytes(RECSTREAM *, char *, u_int);
static bool_t   set_input_fragment(RECSTREAM *);
static bool_t   skip_input_bytes(RECSTREAM *, u_int);
static bool_t   realloc_stream(RECSTREAM *, u_int);


/*
 * Create an xdr handle for xdrrec
 * xdrrec_create fills in xdrs.  Sendsize and recvsize are
 * send and recv buffer sizes (0 => use default).
 * tcp_handle is an opaque handle that is passed as the first parameter to
 * the procedures readit and writeit.  Readit and writeit are read and
 * write respectively.   They are like the system
 * calls expect that they take an opaque handle rather than an fd.
 */
void
xdrrec_create(xdrs, sendsize, recvsize, tcp_handle, readit, writeit)
    XDR *xdrs;
    u_int sendsize;
    u_int recvsize;
    void *tcp_handle;
    /* like read, but pass it a tcp_handle, not sock */
    int (*readit)(void *, void *, int);
    /* like write, but pass it a tcp_handle, not sock */
    int (*writeit)(void *, void *, int);
{
    RECSTREAM *rstrm = mem_alloc(sizeof(RECSTREAM));

    if (rstrm == NULL) {
        //warnx("xdrrec_create: out of memory");
        /* 
         *  This is bad.  Should rework xdrrec_create to 
         *  return a handle, and in this case return NULL
         */
        return;
    }
    rstrm->sendsize = sendsize = fix_buf_size(sendsize);
    rstrm->out_base = mem_alloc(rstrm->sendsize);
    if (rstrm->out_base == NULL) {
        //warnx("xdrrec_create: out of memory");
        mem_free(rstrm, sizeof(RECSTREAM));
        return;
    }
    rstrm->recvsize = recvsize = fix_buf_size(recvsize);
    rstrm->in_base = mem_alloc(recvsize);
    if (rstrm->in_base == NULL) {
        //warnx("xdrrec_create: out of memory");
        mem_free(rstrm->out_base, sendsize);
        mem_free(rstrm, sizeof(RECSTREAM));
        return;
    }
    /*
     * now the rest ...
     */
    xdrs->x_ops = &xdrrec_ops;
    xdrs->x_private = rstrm;
    rstrm->tcp_handle = tcp_handle;
    rstrm->readit = readit;
    rstrm->writeit = writeit;
    rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
    rstrm->frag_header = (u_int32_t *)(void *)rstrm->out_base;
    rstrm->out_finger += sizeof(u_int32_t);
    rstrm->out_boundry += sendsize;
    rstrm->frag_sent = FALSE;
    rstrm->in_size = recvsize;
    rstrm->in_boundry = rstrm->in_base;
    rstrm->in_finger = (rstrm->in_boundry += recvsize);
    rstrm->fbtbc = 0;
    rstrm->last_frag = TRUE;
    rstrm->in_haveheader = FALSE;
    rstrm->in_hdrlen = 0;
    rstrm->in_hdrp = (char *)(void *)&rstrm->in_header;
    rstrm->nonblock = FALSE;
    rstrm->in_reclen = 0;
    rstrm->in_received = 0;
}


/*
 * The reoutines defined below are the xdr ops which will go into the
 * xdr handle filled in by xdrrec_create.
 */

static bool_t
xdrrec_getlong(xdrs, lp)
    XDR *xdrs;
    long *lp;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    int32_t *buflp = (int32_t *)(void *)(rstrm->in_finger);
    int32_t mylong;

    /* first try the inline, fast case */
    if ((rstrm->fbtbc >= sizeof(int32_t)) &&
        ((PtrToLong(rstrm->in_boundry) - PtrToLong(buflp)) >= sizeof(int32_t))) {
        *lp = (long)ntohl((u_int32_t)(*buflp));
        rstrm->fbtbc -= sizeof(int32_t);
        rstrm->in_finger += sizeof(int32_t);
    } else {
        if (! xdrrec_getbytes(xdrs, (char *)(void *)&mylong,
            sizeof(int32_t)))
            return (FALSE);
        *lp = (long)ntohl((u_int32_t)mylong);
    }
    return (TRUE);
}

static bool_t
xdrrec_putlong(xdrs, lp)
    XDR *xdrs;
    const long *lp;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    int32_t *dest_lp = ((int32_t *)(void *)(rstrm->out_finger));

    if ((rstrm->out_finger += sizeof(int32_t)) > rstrm->out_boundry) {
        /*
         * this case should almost never happen so the code is
         * inefficient
         */
        rstrm->out_finger -= sizeof(int32_t);
        rstrm->frag_sent = TRUE;
        if (! flush_out(rstrm, FALSE))
            return (FALSE);
        dest_lp = ((int32_t *)(void *)(rstrm->out_finger));
        rstrm->out_finger += sizeof(int32_t);
    }
    *dest_lp = (int32_t)htonl((u_int32_t)(*lp));
    return (TRUE);
}

static bool_t  /* must manage buffers, fragments, and records */
xdrrec_getbytes(xdrs, addr, len)
    XDR *xdrs;
    char *addr;
    u_int len;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    u_int current;

    while (len > 0) {
        current = (int)rstrm->fbtbc;
        if (current == 0) {
            if (rstrm->last_frag)
                return (FALSE);
            if (! set_input_fragment(rstrm))
                return (FALSE);
            continue;
        }
        current = (len < current) ? len : current;
        if (! get_input_bytes(rstrm, addr, current))
            return (FALSE);
        addr += current; 
        rstrm->fbtbc -= current;
        len -= current;
    }
    return (TRUE);
}

static bool_t
xdrrec_putbytes(xdrs, addr, len)
    XDR *xdrs;
    const char *addr;
    u_int len;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    size_t current;

    while (len > 0) {
        current = (size_t)(PtrToUlong(rstrm->out_boundry) -
            PtrToUlong(rstrm->out_finger));
        current = (len < current) ? len : current;
        memmove(rstrm->out_finger, addr, current);
        rstrm->out_finger += current;
        addr += current;
        len -= current;
        if (rstrm->out_finger == rstrm->out_boundry) {
            rstrm->frag_sent = TRUE;
            if (! flush_out(rstrm, FALSE))
                return (FALSE);
        }
    }
    return (TRUE);
}

static u_int
xdrrec_getpos(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
    off_t pos = 0;

    //pos = lseek((int)(u_long)rstrm->tcp_handle, (off_t)0, 1);
    //pos = _lseek((int)PtrToUlong(rstrm->tcp_handle), (off_t)0, 1);
    if (pos != -1)
        switch (xdrs->x_op) {

        case XDR_ENCODE:
            pos += PtrToLong(rstrm->out_finger) - PtrToLong(rstrm->out_base);
            break;

        case XDR_DECODE:
            pos -= PtrToLong(rstrm->in_boundry) - PtrToLong(rstrm->in_finger);
            break;

        default:
            pos = (off_t) -1;
            break;
        }
    return ((u_int) pos);
}

static bool_t
xdrrec_setpos(xdrs, pos)
    XDR *xdrs;
    u_int pos;
{
    RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
    u_int currpos = xdrrec_getpos(xdrs);
    int delta = currpos - pos;
    char *newpos;

    if ((int)currpos != -1)
        switch (xdrs->x_op) {

        case XDR_ENCODE:
            newpos = rstrm->out_finger - delta;
            if ((newpos > (char *)(void *)(rstrm->frag_header)) &&
                (newpos < rstrm->out_boundry)) {
                rstrm->out_finger = newpos;
                return (TRUE);
            }
            break;

        case XDR_DECODE:
            newpos = rstrm->in_finger - delta;
            if ((delta < (int)(rstrm->fbtbc)) &&
                (newpos <= rstrm->in_boundry) &&
                (newpos >= rstrm->in_base)) {
                rstrm->in_finger = newpos;
                rstrm->fbtbc -= delta;
                return (TRUE);
            }
            break;

        case XDR_FREE:
            break;
        }
    return (FALSE);
}

int32_t *
xdrrec_getoutbase(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
    int32_t *buf = NULL;

    switch (xdrs->x_op) {

    case XDR_ENCODE:
        buf = rstrm->out_base;
        break;

    case XDR_DECODE:
        break;

    case XDR_FREE:
        break;
    }
    return (buf);
}

static int32_t *
xdrrec_inline(xdrs, len)
    XDR *xdrs;
    u_int len;
{
    RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
    int32_t *buf = NULL;

    switch (xdrs->x_op) {

    case XDR_ENCODE:
        if ((rstrm->out_finger + len) <= rstrm->out_boundry) {
            buf = (int32_t *)(void *)rstrm->out_finger;
            rstrm->out_finger += len;
        }
        break;

    case XDR_DECODE:
        if ((len <= rstrm->fbtbc) &&
            ((rstrm->in_finger + len) <= rstrm->in_boundry)) {
            buf = (int32_t *)(void *)rstrm->in_finger;
            rstrm->fbtbc -= len;
            rstrm->in_finger += len;
        }
        break;

    case XDR_FREE:
        break;
    }
    return (buf);
}

static void
xdrrec_destroy(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;

    mem_free(rstrm->out_base, rstrm->sendsize);
    mem_free(rstrm->in_base, rstrm->recvsize);
    mem_free(rstrm, sizeof(RECSTREAM));
}


/*
 * Exported routines to manage xdr records
 */

/*
 * Before reading (deserializing from the stream, one should always call
 * this procedure to guarantee proper record alignment.
 */
void xdrrec_setlastfrag(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    rstrm->last_frag = 1;
}

bool_t
xdrrec_skiprecord(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    enum xprt_stat xstat;

    if (rstrm->nonblock) {
        if (__xdrrec_getrec(xdrs, &xstat, FALSE))
            return TRUE;

        if (rstrm->in_finger == rstrm->in_boundry &&
            xstat == XPRT_MOREREQS) {
            rstrm->fbtbc = 0;
            return TRUE;
        }
        return FALSE;
    }

    while (rstrm->fbtbc > 0 || (! rstrm->last_frag)) {
        if (! skip_input_bytes(rstrm, rstrm->fbtbc))
            return (FALSE);
        rstrm->fbtbc = 0;
        if ((! rstrm->last_frag) && (! set_input_fragment(rstrm)))
            return (FALSE);
    }
    rstrm->last_frag = FALSE;
    return (TRUE);
}

/*
 * Look ahead function.
 * Returns TRUE iff there is no more input in the buffer
 * after consuming the rest of the current record.
 */
bool_t
xdrrec_eof(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);

    while (rstrm->fbtbc > 0 || (! rstrm->last_frag)) {
        if (! skip_input_bytes(rstrm, rstrm->fbtbc))
            return (TRUE);
        rstrm->fbtbc = 0;
        if ((! rstrm->last_frag) && (! set_input_fragment(rstrm)))
            return (TRUE);
    }
    if (rstrm->in_finger == rstrm->in_boundry)
        return (TRUE);
    return (FALSE);
}

/*
 * The client must tell the package when an end-of-record has occurred.
 * The second paraemters tells whether the record should be flushed to the
 * (output) tcp stream.  (This let's the package support batched or
 * pipelined procedure calls.)  TRUE => immmediate flush to tcp connection.
 */
bool_t
xdrrec_endofrecord(xdrs, sendnow)
    XDR *xdrs;
    bool_t sendnow;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    u_long len;  /* fragment length */

    if (sendnow || rstrm->frag_sent ||
        (PtrToUlong(rstrm->out_finger) + sizeof(u_int32_t) >=
        PtrToUlong(rstrm->out_boundry))) {
        rstrm->frag_sent = FALSE;
        return (flush_out(rstrm, TRUE));
    }
    len = PtrToUlong(rstrm->out_finger) - PtrToUlong(rstrm->frag_header) -
       sizeof(u_int32_t);
    *(rstrm->frag_header) = htonl((u_int32_t)len | LAST_FRAG);
    rstrm->frag_header = (u_int32_t *)(void *)rstrm->out_finger;
    rstrm->out_finger += sizeof(u_int32_t);
    return (TRUE);
}

/*
 * Fill the stream buffer with a record for a non-blocking connection.
 * Return true if a record is available in the buffer, false if not.
 */
bool_t
__xdrrec_getrec(xdrs, statp, expectdata)
    XDR *xdrs;
    enum xprt_stat *statp;
    bool_t expectdata;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
    int n;
    u_int fraglen;

    if (!rstrm->in_haveheader) {
        n = rstrm->readit(rstrm->tcp_handle, rstrm->in_hdrp,
            (int)sizeof (rstrm->in_header) - rstrm->in_hdrlen);
        if (n == 0) {
            *statp = expectdata ? XPRT_DIED : XPRT_IDLE;
            return FALSE;
        }
        if (n < 0) {
            *statp = XPRT_DIED;
            return FALSE;
        }
        rstrm->in_hdrp += n;
        rstrm->in_hdrlen += n;
        if (rstrm->in_hdrlen < sizeof (rstrm->in_header)) {
            *statp = XPRT_MOREREQS;
            return FALSE;
        }
        rstrm->in_header = ntohl(rstrm->in_header);
        fraglen = (int)(rstrm->in_header & ~LAST_FRAG);
        if (fraglen == 0 || fraglen > rstrm->in_maxrec ||
            (rstrm->in_reclen + fraglen) > rstrm->in_maxrec) {
            *statp = XPRT_DIED;
            return FALSE;
        }
        rstrm->fbtbc = rstrm->in_header & (~LAST_FRAG);
        rstrm->in_reclen += fraglen;
        if (rstrm->in_reclen > rstrm->recvsize)
            realloc_stream(rstrm, rstrm->in_reclen);
        if (rstrm->in_header & LAST_FRAG) {
            rstrm->in_header &= ~LAST_FRAG;
            rstrm->last_frag = TRUE;
        }
    }

    do {
        n =  rstrm->readit(rstrm->tcp_handle,
            rstrm->in_base + rstrm->in_received,
            (rstrm->in_reclen - rstrm->in_received));

        /* this case is needed for non-block as socket returns TIMEDOUT and -1
         * -2 is an error case and covered by the next if() statement */
        if (n == -1) continue;

        if (n < 0) {
            *statp = XPRT_DIED;
            return FALSE;
        }

        if (n == 0) {
            *statp = expectdata ? XPRT_DIED : XPRT_IDLE;
            return FALSE;
        }

        rstrm->in_received += n;
        if (rstrm->in_received == rstrm->in_reclen) {
            rstrm->in_haveheader = FALSE;
            rstrm->in_hdrp = (char *)(void *)&rstrm->in_header;
            rstrm->in_hdrlen = 0;
            if (rstrm->last_frag) {
                rstrm->in_boundry = rstrm->in_base + rstrm->in_reclen;
                rstrm->in_finger = rstrm->in_base;
                rstrm->in_reclen = rstrm->in_received = 0;
                *statp = XPRT_MOREREQS;
                return TRUE;
            }
        } 
    } while (1);

    *statp = XPRT_MOREREQS;
    return FALSE;
}

bool_t
__xdrrec_setnonblock(xdrs, maxrec)
    XDR *xdrs;
    int maxrec;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);

    rstrm->nonblock = TRUE;
    if (maxrec == 0)
        maxrec = rstrm->recvsize;
    rstrm->in_maxrec = maxrec;
    return TRUE;
}

bool_t
__xdrrec_setblock(xdrs)
    XDR *xdrs;
{
    RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);

    rstrm->nonblock = FALSE;
    return TRUE;
}
/*
 * Internal useful routines
 */
static bool_t
flush_out(rstrm, eor)
    RECSTREAM *rstrm;
    bool_t eor;
{
    u_int32_t eormask = (eor == TRUE) ? LAST_FRAG : 0;
    u_int32_t len = (u_int32_t)(PtrToUlong(rstrm->out_finger) - 
        PtrToUlong(rstrm->frag_header) - sizeof(u_int32_t));

    *(rstrm->frag_header) = htonl(len | eormask);
    len = (u_int32_t)(PtrToUlong(rstrm->out_finger) - 
        PtrToUlong(rstrm->out_base));
    if ((*(rstrm->writeit))(rstrm->tcp_handle, rstrm->out_base, (int)len)
        != (int)len)
        return (FALSE);
    rstrm->frag_header = (u_int32_t *)(void *)rstrm->out_base;
    rstrm->out_finger = (char *)rstrm->out_base + sizeof(u_int32_t);
    return (TRUE);
}

static bool_t  /* knows nothing about records!  Only about input buffers */
fill_input_buf(rstrm)
    RECSTREAM *rstrm;
{
    char *where;
    u_int32_t i;
    int len;

    if (rstrm->nonblock)
        return FALSE;

    where = rstrm->in_base;
    i = (u_int32_t)(PtrToUlong(rstrm->in_boundry) % BYTES_PER_XDR_UNIT);
    where += i;
    len = (u_int32_t)(rstrm->in_size - i);
    if ((len = (*(rstrm->readit))(rstrm->tcp_handle, where, len)) == -1)
        return (FALSE);
    rstrm->in_finger = where;
    where += len;
    rstrm->in_boundry = where;
    return (TRUE);
}

static bool_t  /* knows nothing about records!  Only about input buffers */
get_input_bytes(rstrm, addr, len)
    RECSTREAM *rstrm;
    char *addr;
    u_int len;
{
    size_t current;

    if (rstrm->nonblock) {
        if (len > (u_int)(rstrm->in_boundry - rstrm->in_finger))
            return FALSE;
        memcpy(addr, rstrm->in_finger, (size_t)len);
        rstrm->in_finger += len;
        return TRUE;
    }

    while (len > 0) {
        current = (size_t)(PtrToLong(rstrm->in_boundry) -
            PtrToLong(rstrm->in_finger));
        if (current == 0) {
            if (! fill_input_buf(rstrm))
                return (FALSE);
            continue;
        }
        current = (len < current) ? len : current;
        memmove(addr, rstrm->in_finger, current);
        rstrm->in_finger += current;
        addr += current;
        len -= current;
    }
    return (TRUE);
}

static bool_t  /* next two bytes of the input stream are treated as a header */
set_input_fragment(rstrm)
    RECSTREAM *rstrm;
{
    u_int32_t header;

    if (rstrm->nonblock)
        return FALSE;
    if (! get_input_bytes(rstrm, (char *)(void *)&header, sizeof(header)))
        return (FALSE);
    header = ntohl(header);
    rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
    /*
     * Sanity check. Try not to accept wildly incorrect
     * record sizes. Unfortunately, the only record size
     * we can positively identify as being 'wildly incorrect'
     * is zero. Ridiculously large record sizes may look wrong,
     * but we don't have any way to be certain that they aren't
     * what the client actually intended to send us.
     */
    if (header == 0)
        return(FALSE);
    rstrm->fbtbc = header & (~LAST_FRAG);
    return (TRUE);
}

static bool_t  /* consumes input bytes; knows nothing about records! */
skip_input_bytes(rstrm, cnt)
    RECSTREAM *rstrm;
    u_int cnt;
{
    u_int32_t current;

    while (cnt > 0) {
        current = (u_int32_t)(PtrToUlong(rstrm->in_boundry) - 
            PtrToUlong(rstrm->in_finger));
        if (current == 0) {
            if (! fill_input_buf(rstrm))
                return (FALSE);
            continue;
        }
        current = (u_int32_t)((cnt < current) ? cnt : current);
        rstrm->in_finger += current;
        cnt -= current;
    }
    return (TRUE);
}

static u_int
fix_buf_size(s)
    u_int s;
{

    if (s < 100)
        s = 4000;
    return (RNDUP(s));
}

/*
 * Reallocate the input buffer for a non-block stream.
 */
static bool_t
realloc_stream(rstrm, size)
    RECSTREAM *rstrm;
    u_int size;
{
    ptrdiff_t diff;
    char *buf;

    if (size > rstrm->recvsize) {
        buf = realloc(rstrm->in_base, (size_t)size);
        if (buf == NULL)
            return FALSE;
        diff = buf - rstrm->in_base;
        rstrm->in_finger += diff;
        rstrm->in_base = buf;
        rstrm->in_boundry = buf + size;
        rstrm->recvsize = size;
        rstrm->in_size = size;
    }

    return TRUE;
}