source: rtems-libbsd/freebsd/lib/libc/xdr/xdr_rec.c @ f41a394

#include <machine/rtems-bsd-user-space.h>

/*      $NetBSD: xdr_rec.c,v 1.18 2000/07/06 03:10:35 christos Exp $    */

/*
 * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
 * unrestricted use provided that this legend is included on all tape
 * media and as a part of the software program in whole or part.  Users
 * may copy or modify Sun RPC without charge, but are not authorized
 * to license or distribute it to anyone else except as part of a product or
 * program developed by the user.
 *
 * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
 * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
 *
 * Sun RPC is provided with no support and without any obligation on the
 * part of Sun Microsystems, Inc. to assist in its use, correction,
 * modification or enhancement.
 *
 * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
 * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
 * OR ANY PART THEREOF.
 *
 * In no event will Sun Microsystems, Inc. be liable for any lost revenue
 * or profits or other special, indirect and consequential damages, even if
 * Sun has been advised of the possibility of such damages.
 *
 * Sun Microsystems, Inc.
 * 2550 Garcia Avenue
 * Mountain View, California  94043
 */

#if defined(LIBC_SCCS) && !defined(lint) 
static char *sccsid2 = "@(#)xdr_rec.c 1.21 87/08/11 Copyr 1984 Sun Micro";
static char *sccsid = "@(#)xdr_rec.c    2.2 88/08/01 4.0 RPCSRC";
#endif
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");

/*
 * 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.
 */

#include "namespace.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.h>
#include <rpc/clnt.h>
#include <sys/stddef.h>
#include "un-namespace.h"
#include "rpc_com.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 */
        long 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;
        int in_hdrlen;
        int in_reclen;
        int in_received;
        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 *, int);
static bool_t   set_input_fragment(RECSTREAM *);
static bool_t   skip_input_bytes(RECSTREAM *, long);
static bool_t   realloc_stream(RECSTREAM *, 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)) &&
                (((long)rstrm->in_boundry - (long)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);
        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)((u_long)rstrm->out_boundry -
                    (u_long)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;

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

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

        case XDR_DECODE:
                pos -= rstrm->in_boundry - 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);
}

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.
 */
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)) {
                        rstrm->fbtbc = 0;
                        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 ||
                ((u_long)rstrm->out_finger + sizeof(u_int32_t) >=
                (u_long)rstrm->out_boundry)) {
                rstrm->frag_sent = FALSE;
                return (flush_out(rstrm, TRUE));
        }
        len = (u_long)(rstrm->out_finger) - (u_long)(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);
        ssize_t n;
        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->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;
                }
                /*
                 * We can only reasonably expect to read once from a
                 * non-blocking stream. Reading the fragment header
                 * may have drained the stream.
                 */
                expectdata = FALSE;
        }

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

        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->fbtbc = rstrm->in_reclen;
                        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;
                }
        }

        *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;
}

/*
 * 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)((u_long)(rstrm->out_finger) - 
                (u_long)(rstrm->frag_header) - sizeof(u_int32_t));

        *(rstrm->frag_header) = htonl(len | eormask);
        len = (u_int32_t)((u_long)(rstrm->out_finger) - 
            (u_long)(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)((u_long)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;
        int len;
{
        size_t current;

        if (rstrm->nonblock) {
                if (len > (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)((long)rstrm->in_boundry -
                    (long)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;
        long cnt;
{
        u_int32_t current;

        while (cnt > 0) {
                current = (size_t)((long)rstrm->in_boundry - 
                    (long)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;
        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;
}