sunrpc/xdr_rec.c

   1 /*
   2  * xdr_rec.c, Implements TCP/IP based XDR streams with a "record marking"
   3  * layer above tcp (for rpc's use).
   4  *
   5  * Copyright (C) 1984, Sun Microsystems, Inc.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are
   9  * met:
  10  *
  11  *     * Redistributions of source code must retain the above copyright
  12  *       notice, this list of conditions and the following disclaimer.
  13  *     * Redistributions in binary form must reproduce the above
  14  *       copyright notice, this list of conditions and the following
  15  *       disclaimer in the documentation and/or other materials
  16  *       provided with the distribution.
  17  *     * Neither the name of Sun Microsystems, Inc. nor the names of its
  18  *       contributors may be used to endorse or promote products derived
  19  *       from this software without specific prior written permission.
  20  *
  21  *   THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  22  *   "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  23  *   LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  24  *   FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  25  *   COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  26  *   INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  *   DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE
  28  *   GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  29  *   INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
  30  *   WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
  31  *   NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  32  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  33  *
  34  * These routines interface XDRSTREAMS to a tcp/ip connection.
  35  * There is a record marking layer between the xdr stream
  36  * and the tcp transport level.  A record is composed on one or more
  37  * record fragments.  A record fragment is a thirty-two bit header followed
  38  * by n bytes of data, where n is contained in the header.  The header
  39  * is represented as a htonl(u_long).  The high order bit encodes
  40  * whether or not the fragment is the last fragment of the record
  41  * (1 => fragment is last, 0 => more fragments to follow.
  42  * The other 31 bits encode the byte length of the fragment.
  43  */
  44
  45 #include <stdio.h>
  46 #include <string.h>
  47 #include <unistd.h>
  48 #include <rpc/rpc.h>
  49 #include <libintl.h>
  50
  51 #ifdef USE_IN_LIBIO
  52 # include <wchar.h>
  53 # include <libio/iolibio.h>
  54 #endif
  55
  56 static bool_t xdrrec_getlong (XDR *, long *);
  57 static bool_t xdrrec_putlong (XDR *, const long *);
  58 static bool_t xdrrec_getbytes (XDR *, caddr_t, u_int);
  59 static bool_t xdrrec_putbytes (XDR *, const char *, u_int);
  60 static u_int xdrrec_getpos (const XDR *);
  61 static bool_t xdrrec_setpos (XDR *, u_int);
  62 static int32_t *xdrrec_inline (XDR *, u_int);
  63 static void xdrrec_destroy (XDR *);
  64 static bool_t xdrrec_getint32 (XDR *, int32_t *);
  65 static bool_t xdrrec_putint32 (XDR *, const int32_t *);
  66
  67 static const struct xdr_ops xdrrec_ops = {
  68   xdrrec_getlong,
  69   xdrrec_putlong,
  70   xdrrec_getbytes,
  71   xdrrec_putbytes,
  72   xdrrec_getpos,
  73   xdrrec_setpos,
  74   xdrrec_inline,
  75   xdrrec_destroy,
  76   xdrrec_getint32,
  77   xdrrec_putint32
  78 };
  79
  80 /*
  81  * A record is composed of one or more record fragments.
  82  * A record fragment is a two-byte header followed by zero to
  83  * 2**32-1 bytes.  The header is treated as a long unsigned and is
  84  * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
  85  * are a byte count of the fragment.  The highest order bit is a boolean:
  86  * 1 => this fragment is the last fragment of the record,
  87  * 0 => this fragment is followed by more fragment(s).
  88  *
  89  * The fragment/record machinery is not general;  it is constructed to
  90  * meet the needs of xdr and rpc based on tcp.
  91  */
  92
  93 #define LAST_FRAG (1UL << 31)
  94
  95 typedef struct rec_strm
  96   {
  97     caddr_t tcp_handle;
  98     caddr_t the_buffer;
  99     /*
 100      * out-going bits
 101      */
 102     int (*writeit) (char *, char *, int);
 103     caddr_t out_base;           /* output buffer (points to frag header) */
 104     caddr_t out_finger;         /* next output position */
 105     caddr_t out_boundry;        /* data cannot up to this address */
 106     u_int32_t *frag_header;     /* beginning of curren fragment */
 107     bool_t frag_sent;           /* true if buffer sent in middle of record */
 108     /*
 109      * in-coming bits
 110      */
 111     int (*readit) (char *, char *, int);
 112     u_long in_size;             /* fixed size of the input buffer */
 113     caddr_t in_base;
 114     caddr_t in_finger;          /* location of next byte to be had */
 115     caddr_t in_boundry;         /* can read up to this location */
 116     long fbtbc;                 /* fragment bytes to be consumed */
 117     bool_t last_frag;
 118     u_int sendsize;
 119     u_int recvsize;
 120   }
 121 RECSTREAM;
 122
 123 static u_int fix_buf_size (u_int) internal_function;
 124 static bool_t skip_input_bytes (RECSTREAM *, long) internal_function;
 125 static bool_t flush_out (RECSTREAM *, bool_t) internal_function;
 126 static bool_t set_input_fragment (RECSTREAM *) internal_function;
 127 static bool_t get_input_bytes (RECSTREAM *, caddr_t, int) internal_function;
 128
 129 /*
 130  * Create an xdr handle for xdrrec
 131  * xdrrec_create fills in xdrs.  Sendsize and recvsize are
 132  * send and recv buffer sizes (0 => use default).
 133  * tcp_handle is an opaque handle that is passed as the first parameter to
 134  * the procedures readit and writeit.  Readit and writeit are read and
 135  * write respectively.   They are like the system
 136  * calls expect that they take an opaque handle rather than an fd.
 137  */
 138 void
 139 xdrrec_create (XDR *xdrs, u_int sendsize,
 140                u_int recvsize, caddr_t tcp_handle,
 141                int (*readit) (char *, char *, int),
 142                int (*writeit) (char *, char *, int))
 143 {
 144   RECSTREAM *rstrm = (RECSTREAM *) mem_alloc (sizeof (RECSTREAM));
 145   caddr_t tmp;
 146   char *buf;
 147
 148   sendsize = fix_buf_size (sendsize);
 149   recvsize = fix_buf_size (recvsize);
 150   buf = mem_alloc (sendsize + recvsize + BYTES_PER_XDR_UNIT);
 151
 152   if (rstrm == NULL || buf == NULL)
 153     {
 154       (void) __fxprintf (NULL, "%s: %s", __func__, _("out of memory\n"));
 155       mem_free (rstrm, sizeof (RECSTREAM));
 156       mem_free (buf, sendsize + recvsize + BYTES_PER_XDR_UNIT);
 157       /*
 158        *  This is bad.  Should rework xdrrec_create to
 159        *  return a handle, and in this case return NULL
 160        */
 161       return;
 162     }
 163   /*
 164    * adjust sizes and allocate buffer quad byte aligned
 165    */
 166   rstrm->sendsize = sendsize;
 167   rstrm->recvsize = recvsize;
 168   rstrm->the_buffer = buf;
 169   tmp = rstrm->the_buffer;
 170   if ((size_t)tmp % BYTES_PER_XDR_UNIT)
 171     tmp += BYTES_PER_XDR_UNIT - (size_t)tmp % BYTES_PER_XDR_UNIT;
 172   rstrm->out_base = tmp;
 173   rstrm->in_base = tmp + sendsize;
 174   /*
 175    * now the rest ...
 176    */
 177   /* We have to add the cast since the `struct xdr_ops' in `struct XDR'
 178      is not `const'.  */
 179   xdrs->x_ops = (struct xdr_ops *) &xdrrec_ops;
 180   xdrs->x_private = (caddr_t) rstrm;
 181   rstrm->tcp_handle = tcp_handle;
 182   rstrm->readit = readit;
 183   rstrm->writeit = writeit;
 184   rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
 185   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 186   rstrm->out_finger += 4;
 187   rstrm->out_boundry += sendsize;
 188   rstrm->frag_sent = FALSE;
 189   rstrm->in_size = recvsize;
 190   rstrm->in_boundry = rstrm->in_base;
 191   rstrm->in_finger = (rstrm->in_boundry += recvsize);
 192   rstrm->fbtbc = 0;
 193   rstrm->last_frag = TRUE;
 194 }
 195 INTDEF(xdrrec_create)
 196
 197
 198 /*
 199  * The routines defined below are the xdr ops which will go into the
 200  * xdr handle filled in by xdrrec_create.
 201  */
 202
 203 static bool_t
 204 xdrrec_getlong (XDR *xdrs, long *lp)
 205 {
 206   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 207   int32_t *buflp = (int32_t *) rstrm->in_finger;
 208   int32_t mylong;
 209
 210   /* first try the inline, fast case */
 211   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 212       rstrm->in_boundry - (char *) buflp >= BYTES_PER_XDR_UNIT)
 213     {
 214       *lp = (int32_t) ntohl (*buflp);
 215       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 216       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 217     }
 218   else
 219     {
 220       if (!xdrrec_getbytes (xdrs, (caddr_t) & mylong,
 221                             BYTES_PER_XDR_UNIT))
 222         return FALSE;
 223       *lp = (int32_t) ntohl (mylong);
 224     }
 225   return TRUE;
 226 }
 227
 228 static bool_t
 229 xdrrec_putlong (XDR *xdrs, const long *lp)
 230 {
 231   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 232   int32_t *dest_lp = (int32_t *) rstrm->out_finger;
 233
 234   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 235     {
 236       /*
 237        * this case should almost never happen so the code is
 238        * inefficient
 239        */
 240       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 241       rstrm->frag_sent = TRUE;
 242       if (!flush_out (rstrm, FALSE))
 243         return FALSE;
 244       dest_lp = (int32_t *) rstrm->out_finger;
 245       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 246     }
 247   *dest_lp = htonl (*lp);
 248   return TRUE;
 249 }
 250
 251 static bool_t      /* must manage buffers, fragments, and records */
 252 xdrrec_getbytes (XDR *xdrs, caddr_t addr, u_int len)
 253 {
 254   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 255   u_int current;
 256
 257   while (len > 0)
 258     {
 259       current = rstrm->fbtbc;
 260       if (current == 0)
 261         {
 262           if (rstrm->last_frag)
 263             return FALSE;
 264           if (!set_input_fragment (rstrm))
 265             return FALSE;
 266           continue;
 267         }
 268       current = (len < current) ? len : current;
 269       if (!get_input_bytes (rstrm, addr, current))
 270         return FALSE;
 271       addr += current;
 272       rstrm->fbtbc -= current;
 273       len -= current;
 274     }
 275   return TRUE;
 276 }
 277
 278 static bool_t
 279 xdrrec_putbytes (XDR *xdrs, const char *addr, u_int len)
 280 {
 281   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 282   u_int current;
 283
 284   while (len > 0)
 285     {
 286       current = rstrm->out_boundry - rstrm->out_finger;
 287       current = (len < current) ? len : current;
 288       memcpy (rstrm->out_finger, addr, current);
 289       rstrm->out_finger += current;
 290       addr += current;
 291       len -= current;
 292       if (rstrm->out_finger == rstrm->out_boundry && len > 0)
 293         {
 294           rstrm->frag_sent = TRUE;
 295           if (!flush_out (rstrm, FALSE))
 296             return FALSE;
 297         }
 298     }
 299   return TRUE;
 300 }
 301
 302 static u_int
 303 xdrrec_getpos (const XDR *xdrs)
 304 {
 305   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 306   long pos;
 307
 308   pos = __lseek ((int) (long) rstrm->tcp_handle, (long) 0, 1);
 309   if (pos != -1)
 310     switch (xdrs->x_op)
 311       {
 312
 313       case XDR_ENCODE:
 314         pos += rstrm->out_finger - rstrm->out_base;
 315         break;
 316
 317       case XDR_DECODE:
 318         pos -= rstrm->in_boundry - rstrm->in_finger;
 319         break;
 320
 321       default:
 322         pos = (u_int) - 1;
 323         break;
 324       }
 325   return (u_int) pos;
 326 }
 327
 328 static bool_t
 329 xdrrec_setpos (XDR *xdrs, u_int pos)
 330 {
 331   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 332   u_int currpos = xdrrec_getpos (xdrs);
 333   int delta = currpos - pos;
 334   caddr_t newpos;
 335
 336   if ((int) currpos != -1)
 337     switch (xdrs->x_op)
 338       {
 339
 340       case XDR_ENCODE:
 341         newpos = rstrm->out_finger - delta;
 342         if (newpos > (caddr_t) rstrm->frag_header &&
 343             newpos < rstrm->out_boundry)
 344           {
 345             rstrm->out_finger = newpos;
 346             return TRUE;
 347           }
 348         break;
 349
 350       case XDR_DECODE:
 351         newpos = rstrm->in_finger - delta;
 352         if ((delta < (int) (rstrm->fbtbc)) &&
 353             (newpos <= rstrm->in_boundry) &&
 354             (newpos >= rstrm->in_base))
 355           {
 356             rstrm->in_finger = newpos;
 357             rstrm->fbtbc -= delta;
 358             return TRUE;
 359           }
 360         break;
 361
 362       default:
 363         break;
 364       }
 365   return FALSE;
 366 }
 367
 368 static int32_t *
 369 xdrrec_inline (XDR *xdrs, u_int len)
 370 {
 371   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 372   int32_t *buf = NULL;
 373
 374   switch (xdrs->x_op)
 375     {
 376
 377     case XDR_ENCODE:
 378       if ((rstrm->out_finger + len) <= rstrm->out_boundry)
 379         {
 380           buf = (int32_t *) rstrm->out_finger;
 381           rstrm->out_finger += len;
 382         }
 383       break;
 384
 385     case XDR_DECODE:
 386       if ((len <= rstrm->fbtbc) &&
 387           ((rstrm->in_finger + len) <= rstrm->in_boundry))
 388         {
 389           buf = (int32_t *) rstrm->in_finger;
 390           rstrm->fbtbc -= len;
 391           rstrm->in_finger += len;
 392         }
 393       break;
 394
 395     default:
 396       break;
 397     }
 398   return buf;
 399 }
 400
 401 static void
 402 xdrrec_destroy (XDR *xdrs)
 403 {
 404   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 405
 406   mem_free (rstrm->the_buffer,
 407             rstrm->sendsize + rstrm->recvsize + BYTES_PER_XDR_UNIT);
 408   mem_free ((caddr_t) rstrm, sizeof (RECSTREAM));
 409 }
 410
 411 static bool_t
 412 xdrrec_getint32 (XDR *xdrs, int32_t *ip)
 413 {
 414   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 415   int32_t *bufip = (int32_t *) rstrm->in_finger;
 416   int32_t mylong;
 417
 418   /* first try the inline, fast case */
 419   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 420       rstrm->in_boundry - (char *) bufip >= BYTES_PER_XDR_UNIT)
 421     {
 422       *ip = ntohl (*bufip);
 423       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 424       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 425     }
 426   else
 427     {
 428       if (!xdrrec_getbytes (xdrs, (caddr_t) &mylong,
 429                             BYTES_PER_XDR_UNIT))
 430         return FALSE;
 431       *ip = ntohl (mylong);
 432     }
 433   return TRUE;
 434 }
 435
 436 static bool_t
 437 xdrrec_putint32 (XDR *xdrs, const int32_t *ip)
 438 {
 439   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 440   int32_t *dest_ip = (int32_t *) rstrm->out_finger;
 441
 442   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 443     {
 444       /*
 445        * this case should almost never happen so the code is
 446        * inefficient
 447        */
 448       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 449       rstrm->frag_sent = TRUE;
 450       if (!flush_out (rstrm, FALSE))
 451         return FALSE;
 452       dest_ip = (int32_t *) rstrm->out_finger;
 453       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 454     }
 455   *dest_ip = htonl (*ip);
 456   return TRUE;
 457 }
 458
 459 /*
 460  * Exported routines to manage xdr records
 461  */
 462
 463 /*
 464  * Before reading (deserializing from the stream, one should always call
 465  * this procedure to guarantee proper record alignment.
 466  */
 467 bool_t
 468 xdrrec_skiprecord (XDR *xdrs)
 469 {
 470   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 471
 472   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 473     {
 474       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 475         return FALSE;
 476       rstrm->fbtbc = 0;
 477       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 478         return FALSE;
 479     }
 480   rstrm->last_frag = FALSE;
 481   return TRUE;
 482 }
 483 INTDEF(xdrrec_skiprecord)
 484
 485 /*
 486  * Lookahead function.
 487  * Returns TRUE iff there is no more input in the buffer
 488  * after consuming the rest of the current record.
 489  */
 490 bool_t
 491 xdrrec_eof (XDR *xdrs)
 492 {
 493   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 494
 495   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 496     {
 497       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 498         return TRUE;
 499       rstrm->fbtbc = 0;
 500       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 501         return TRUE;
 502     }
 503   if (rstrm->in_finger == rstrm->in_boundry)
 504     return TRUE;
 505   return FALSE;
 506 }
 507 INTDEF(xdrrec_eof)
 508
 509 /*
 510  * The client must tell the package when an end-of-record has occurred.
 511  * The second parameter tells whether the record should be flushed to the
 512  * (output) tcp stream.  (This lets the package support batched or
 513  * pipelined procedure calls.)  TRUE => immediate flush to tcp connection.
 514  */
 515 bool_t
 516 xdrrec_endofrecord (XDR *xdrs, bool_t sendnow)
 517 {
 518   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 519   u_long len;           /* fragment length */
 520
 521   if (sendnow || rstrm->frag_sent
 522       || rstrm->out_finger + BYTES_PER_XDR_UNIT >= rstrm->out_boundry)
 523     {
 524       rstrm->frag_sent = FALSE;
 525       return flush_out (rstrm, TRUE);
 526     }
 527   len = (rstrm->out_finger - (char *) rstrm->frag_header
 528          - BYTES_PER_XDR_UNIT);
 529   *rstrm->frag_header = htonl ((u_long) len | LAST_FRAG);
 530   rstrm->frag_header = (u_int32_t *) rstrm->out_finger;
 531   rstrm->out_finger += BYTES_PER_XDR_UNIT;
 532   return TRUE;
 533 }
 534 INTDEF(xdrrec_endofrecord)
 535
 536
 537 /*
 538  * Internal useful routines
 539  */
 540 static bool_t
 541 internal_function
 542 flush_out (RECSTREAM *rstrm, bool_t eor)
 543 {
 544   u_long eormask = (eor == TRUE) ? LAST_FRAG : 0;
 545   u_long len = (rstrm->out_finger - (char *) rstrm->frag_header
 546                 - BYTES_PER_XDR_UNIT);
 547
 548   *rstrm->frag_header = htonl (len | eormask);
 549   len = rstrm->out_finger - rstrm->out_base;
 550   if ((*(rstrm->writeit)) (rstrm->tcp_handle, rstrm->out_base, (int) len)
 551       != (int) len)
 552     return FALSE;
 553   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 554   rstrm->out_finger = (caddr_t) rstrm->out_base + BYTES_PER_XDR_UNIT;
 555   return TRUE;
 556 }
 557
 558 static bool_t   /* knows nothing about records!  Only about input buffers */
 559 fill_input_buf (RECSTREAM *rstrm)
 560 {
 561   caddr_t where;
 562   size_t i;
 563   int len;
 564
 565   where = rstrm->in_base;
 566   i = (size_t) rstrm->in_boundry % BYTES_PER_XDR_UNIT;
 567   where += i;
 568   len = rstrm->in_size - i;
 569   if ((len = (*(rstrm->readit)) (rstrm->tcp_handle, where, len)) == -1)
 570     return FALSE;
 571   rstrm->in_finger = where;
 572   where += len;
 573   rstrm->in_boundry = where;
 574   return TRUE;
 575 }
 576
 577 static bool_t   /* knows nothing about records!  Only about input buffers */
 578 internal_function
 579 get_input_bytes (RECSTREAM *rstrm, caddr_t addr, int len)
 580 {
 581   int current;
 582
 583   while (len > 0)
 584     {
 585       current = rstrm->in_boundry - rstrm->in_finger;
 586       if (current == 0)
 587         {
 588           if (!fill_input_buf (rstrm))
 589             return FALSE;
 590           continue;
 591         }
 592       current = (len < current) ? len : current;
 593       memcpy (addr, rstrm->in_finger, current);
 594       rstrm->in_finger += current;
 595       addr += current;
 596       len -= current;
 597     }
 598   return TRUE;
 599 }
 600
 601 static bool_t /* next two bytes of the input stream are treated as a header */
 602 internal_function
 603 set_input_fragment (RECSTREAM *rstrm)
 604 {
 605   uint32_t header;
 606
 607   if (! get_input_bytes (rstrm, (caddr_t)&header, BYTES_PER_XDR_UNIT))
 608     return FALSE;
 609   header = ntohl (header);
 610   rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
 611   /*
 612    * Sanity check. Try not to accept wildly incorrect fragment
 613    * sizes. Unfortunately, only a size of zero can be identified as
 614    * 'wildely incorrect', and this only, if it is not the last
 615    * fragment of a message. Ridiculously large fragment sizes may look
 616    * wrong, but we don't have any way to be certain that they aren't
 617    * what the client actually intended to send us. Many existing RPC
 618    * implementations may sent a fragment of size zero as the last
 619    * fragment of a message.
 620    */
 621   if (header == 0)
 622     return FALSE;
 623   rstrm->fbtbc = header & ~LAST_FRAG;
 624   return TRUE;
 625 }
 626
 627 static bool_t   /* consumes input bytes; knows nothing about records! */
 628 internal_function
 629 skip_input_bytes (RECSTREAM *rstrm, long cnt)
 630 {
 631   int current;
 632
 633   while (cnt > 0)
 634     {
 635       current = rstrm->in_boundry - rstrm->in_finger;
 636       if (current == 0)
 637         {
 638           if (!fill_input_buf (rstrm))
 639             return FALSE;
 640           continue;
 641         }
 642       current = (cnt < current) ? cnt : current;
 643       rstrm->in_finger += current;
 644       cnt -= current;
 645     }
 646   return TRUE;
 647 }
 648
 649 static u_int
 650 internal_function
 651 fix_buf_size (u_int s)
 652 {
 653   if (s < 100)
 654     s = 4000;
 655   return RNDUP (s);
 656 }