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) 2010, Oracle America, 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 the "Oracle America, 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 <stdint.h>
  49 #include <rpc/rpc.h>
  50 #include <libintl.h>
  51 #include <wchar.h>
  52 #include <libio/iolibio.h>
  53
  54 static bool_t xdrrec_getlong (XDR *, long *);
  55 static bool_t xdrrec_putlong (XDR *, const long *);
  56 static bool_t xdrrec_getbytes (XDR *, caddr_t, u_int);
  57 static bool_t xdrrec_putbytes (XDR *, const char *, u_int);
  58 static u_int xdrrec_getpos (const XDR *);
  59 static bool_t xdrrec_setpos (XDR *, u_int);
  60 static int32_t *xdrrec_inline (XDR *, u_int);
  61 static void xdrrec_destroy (XDR *);
  62 static bool_t xdrrec_getint32 (XDR *, int32_t *);
  63 static bool_t xdrrec_putint32 (XDR *, const int32_t *);
  64
  65 static const struct xdr_ops xdrrec_ops = {
  66   xdrrec_getlong,
  67   xdrrec_putlong,
  68   xdrrec_getbytes,
  69   xdrrec_putbytes,
  70   xdrrec_getpos,
  71   xdrrec_setpos,
  72   xdrrec_inline,
  73   xdrrec_destroy,
  74   xdrrec_getint32,
  75   xdrrec_putint32
  76 };
  77
  78 /*
  79  * A record is composed of one or more record fragments.
  80  * A record fragment is a two-byte header followed by zero to
  81  * 2**32-1 bytes.  The header is treated as a long unsigned and is
  82  * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
  83  * are a byte count of the fragment.  The highest order bit is a boolean:
  84  * 1 => this fragment is the last fragment of the record,
  85  * 0 => this fragment is followed by more fragment(s).
  86  *
  87  * The fragment/record machinery is not general;  it is constructed to
  88  * meet the needs of xdr and rpc based on tcp.
  89  */
  90
  91 #define LAST_FRAG (1UL << 31)
  92
  93 typedef struct rec_strm
  94   {
  95     caddr_t tcp_handle;
  96     caddr_t the_buffer;
  97     /*
  98      * out-going bits
  99      */
 100     int (*writeit) (char *, char *, int);
 101     caddr_t out_base;           /* output buffer (points to frag header) */
 102     caddr_t out_finger;         /* next output position */
 103     caddr_t out_boundry;        /* data cannot up to this address */
 104     u_int32_t *frag_header;     /* beginning of curren fragment */
 105     bool_t frag_sent;           /* true if buffer sent in middle of record */
 106     /*
 107      * in-coming bits
 108      */
 109     int (*readit) (char *, char *, int);
 110     u_long in_size;             /* fixed size of the input buffer */
 111     caddr_t in_base;
 112     caddr_t in_finger;          /* location of next byte to be had */
 113     caddr_t in_boundry;         /* can read up to this location */
 114     long fbtbc;                 /* fragment bytes to be consumed */
 115     bool_t last_frag;
 116     u_int sendsize;
 117     u_int recvsize;
 118   }
 119 RECSTREAM;
 120
 121 static u_int fix_buf_size (u_int) internal_function;
 122 static bool_t skip_input_bytes (RECSTREAM *, long) internal_function;
 123 static bool_t flush_out (RECSTREAM *, bool_t) internal_function;
 124 static bool_t set_input_fragment (RECSTREAM *) internal_function;
 125 static bool_t get_input_bytes (RECSTREAM *, caddr_t, int) internal_function;
 126
 127 /*
 128  * Create an xdr handle for xdrrec
 129  * xdrrec_create fills in xdrs.  Sendsize and recvsize are
 130  * send and recv buffer sizes (0 => use default).
 131  * tcp_handle is an opaque handle that is passed as the first parameter to
 132  * the procedures readit and writeit.  Readit and writeit are read and
 133  * write respectively.   They are like the system
 134  * calls expect that they take an opaque handle rather than an fd.
 135  */
 136 void
 137 xdrrec_create (XDR *xdrs, u_int sendsize,
 138                u_int recvsize, caddr_t tcp_handle,
 139                int (*readit) (char *, char *, int),
 140                int (*writeit) (char *, char *, int))
 141 {
 142   RECSTREAM *rstrm = (RECSTREAM *) mem_alloc (sizeof (RECSTREAM));
 143   caddr_t tmp;
 144   char *buf;
 145
 146   sendsize = fix_buf_size (sendsize);
 147   recvsize = fix_buf_size (recvsize);
 148   buf = mem_alloc (sendsize + recvsize + BYTES_PER_XDR_UNIT);
 149
 150   if (rstrm == NULL || buf == NULL)
 151     {
 152       (void) __fxprintf (NULL, "%s: %s", __func__, _("out of memory\n"));
 153       mem_free (rstrm, sizeof (RECSTREAM));
 154       mem_free (buf, sendsize + recvsize + BYTES_PER_XDR_UNIT);
 155       /*
 156        *  This is bad.  Should rework xdrrec_create to
 157        *  return a handle, and in this case return NULL
 158        */
 159       return;
 160     }
 161   /*
 162    * adjust sizes and allocate buffer quad byte aligned
 163    */
 164   rstrm->sendsize = sendsize;
 165   rstrm->recvsize = recvsize;
 166   rstrm->the_buffer = buf;
 167   tmp = rstrm->the_buffer;
 168   if ((size_t)tmp % BYTES_PER_XDR_UNIT)
 169     tmp += BYTES_PER_XDR_UNIT - (size_t)tmp % BYTES_PER_XDR_UNIT;
 170   rstrm->out_base = tmp;
 171   rstrm->in_base = tmp + sendsize;
 172   /*
 173    * now the rest ...
 174    */
 175   /* We have to add the cast since the `struct xdr_ops' in `struct XDR'
 176      is not `const'.  */
 177   xdrs->x_ops = (struct xdr_ops *) &xdrrec_ops;
 178   xdrs->x_private = (caddr_t) rstrm;
 179   rstrm->tcp_handle = tcp_handle;
 180   rstrm->readit = readit;
 181   rstrm->writeit = writeit;
 182   rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
 183   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 184   rstrm->out_finger += 4;
 185   rstrm->out_boundry += sendsize;
 186   rstrm->frag_sent = FALSE;
 187   rstrm->in_size = recvsize;
 188   rstrm->in_boundry = rstrm->in_base;
 189   rstrm->in_finger = (rstrm->in_boundry += recvsize);
 190   rstrm->fbtbc = 0;
 191   rstrm->last_frag = TRUE;
 192 }
 193 libc_hidden_nolink_sunrpc (xdrrec_create, GLIBC_2_0)
 194
 195
 196 /*
 197  * The routines defined below are the xdr ops which will go into the
 198  * xdr handle filled in by xdrrec_create.
 199  */
 200
 201 static bool_t
 202 xdrrec_getlong (XDR *xdrs, long *lp)
 203 {
 204   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 205   int32_t *buflp = (int32_t *) rstrm->in_finger;
 206   int32_t mylong;
 207
 208   /* first try the inline, fast case */
 209   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 210       rstrm->in_boundry - (char *) buflp >= BYTES_PER_XDR_UNIT)
 211     {
 212       *lp = (int32_t) ntohl (*buflp);
 213       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 214       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 215     }
 216   else
 217     {
 218       if (!xdrrec_getbytes (xdrs, (caddr_t) & mylong,
 219                             BYTES_PER_XDR_UNIT))
 220         return FALSE;
 221       *lp = (int32_t) ntohl (mylong);
 222     }
 223   return TRUE;
 224 }
 225
 226 static bool_t
 227 xdrrec_putlong (XDR *xdrs, const long *lp)
 228 {
 229   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 230   int32_t *dest_lp = (int32_t *) rstrm->out_finger;
 231
 232   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 233     {
 234       /*
 235        * this case should almost never happen so the code is
 236        * inefficient
 237        */
 238       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 239       rstrm->frag_sent = TRUE;
 240       if (!flush_out (rstrm, FALSE))
 241         return FALSE;
 242       dest_lp = (int32_t *) rstrm->out_finger;
 243       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 244     }
 245   *dest_lp = htonl (*lp);
 246   return TRUE;
 247 }
 248
 249 static bool_t      /* must manage buffers, fragments, and records */
 250 xdrrec_getbytes (XDR *xdrs, caddr_t addr, u_int len)
 251 {
 252   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 253   u_int current;
 254
 255   while (len > 0)
 256     {
 257       current = rstrm->fbtbc;
 258       if (current == 0)
 259         {
 260           if (rstrm->last_frag)
 261             return FALSE;
 262           if (!set_input_fragment (rstrm))
 263             return FALSE;
 264           continue;
 265         }
 266       current = (len < current) ? len : current;
 267       if (!get_input_bytes (rstrm, addr, current))
 268         return FALSE;
 269       addr += current;
 270       rstrm->fbtbc -= current;
 271       len -= current;
 272     }
 273   return TRUE;
 274 }
 275
 276 static bool_t
 277 xdrrec_putbytes (XDR *xdrs, const char *addr, u_int len)
 278 {
 279   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 280   u_int current;
 281
 282   while (len > 0)
 283     {
 284       current = rstrm->out_boundry - rstrm->out_finger;
 285       current = (len < current) ? len : current;
 286       memcpy (rstrm->out_finger, addr, current);
 287       rstrm->out_finger += current;
 288       addr += current;
 289       len -= current;
 290       if (rstrm->out_finger == rstrm->out_boundry && len > 0)
 291         {
 292           rstrm->frag_sent = TRUE;
 293           if (!flush_out (rstrm, FALSE))
 294             return FALSE;
 295         }
 296     }
 297   return TRUE;
 298 }
 299
 300 static u_int
 301 xdrrec_getpos (const XDR *xdrs)
 302 {
 303   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 304   long pos;
 305
 306   pos = __lseek ((int) (long) rstrm->tcp_handle, (long) 0, 1);
 307   if (pos != -1)
 308     switch (xdrs->x_op)
 309       {
 310
 311       case XDR_ENCODE:
 312         pos += rstrm->out_finger - rstrm->out_base;
 313         break;
 314
 315       case XDR_DECODE:
 316         pos -= rstrm->in_boundry - rstrm->in_finger;
 317         break;
 318
 319       default:
 320         pos = (u_int) - 1;
 321         break;
 322       }
 323   return (u_int) pos;
 324 }
 325
 326 static bool_t
 327 xdrrec_setpos (XDR *xdrs, u_int pos)
 328 {
 329   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 330   u_int currpos = xdrrec_getpos (xdrs);
 331   int delta = currpos - pos;
 332   caddr_t newpos;
 333
 334   if ((int) currpos != -1)
 335     switch (xdrs->x_op)
 336       {
 337
 338       case XDR_ENCODE:
 339         newpos = rstrm->out_finger - delta;
 340         if (newpos > (caddr_t) rstrm->frag_header &&
 341             newpos < rstrm->out_boundry)
 342           {
 343             rstrm->out_finger = newpos;
 344             return TRUE;
 345           }
 346         break;
 347
 348       case XDR_DECODE:
 349         newpos = rstrm->in_finger - delta;
 350         if ((delta < (int) (rstrm->fbtbc)) &&
 351             (newpos <= rstrm->in_boundry) &&
 352             (newpos >= rstrm->in_base))
 353           {
 354             rstrm->in_finger = newpos;
 355             rstrm->fbtbc -= delta;
 356             return TRUE;
 357           }
 358         break;
 359
 360       default:
 361         break;
 362       }
 363   return FALSE;
 364 }
 365
 366 static int32_t *
 367 xdrrec_inline (XDR *xdrs, u_int len)
 368 {
 369   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 370   int32_t *buf = NULL;
 371
 372   switch (xdrs->x_op)
 373     {
 374
 375     case XDR_ENCODE:
 376       if ((rstrm->out_finger + len) <= rstrm->out_boundry)
 377         {
 378           buf = (int32_t *) rstrm->out_finger;
 379           rstrm->out_finger += len;
 380         }
 381       break;
 382
 383     case XDR_DECODE:
 384       if ((len <= rstrm->fbtbc) &&
 385           ((rstrm->in_finger + len) <= rstrm->in_boundry))
 386         {
 387           buf = (int32_t *) rstrm->in_finger;
 388           rstrm->fbtbc -= len;
 389           rstrm->in_finger += len;
 390         }
 391       break;
 392
 393     default:
 394       break;
 395     }
 396   return buf;
 397 }
 398
 399 static void
 400 xdrrec_destroy (XDR *xdrs)
 401 {
 402   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 403
 404   mem_free (rstrm->the_buffer,
 405             rstrm->sendsize + rstrm->recvsize + BYTES_PER_XDR_UNIT);
 406   mem_free ((caddr_t) rstrm, sizeof (RECSTREAM));
 407 }
 408
 409 static bool_t
 410 xdrrec_getint32 (XDR *xdrs, int32_t *ip)
 411 {
 412   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 413   int32_t *bufip = (int32_t *) rstrm->in_finger;
 414   int32_t mylong;
 415
 416   /* first try the inline, fast case */
 417   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 418       rstrm->in_boundry - (char *) bufip >= BYTES_PER_XDR_UNIT)
 419     {
 420       *ip = ntohl (*bufip);
 421       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 422       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 423     }
 424   else
 425     {
 426       if (!xdrrec_getbytes (xdrs, (caddr_t) &mylong,
 427                             BYTES_PER_XDR_UNIT))
 428         return FALSE;
 429       *ip = ntohl (mylong);
 430     }
 431   return TRUE;
 432 }
 433
 434 static bool_t
 435 xdrrec_putint32 (XDR *xdrs, const int32_t *ip)
 436 {
 437   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 438   int32_t *dest_ip = (int32_t *) rstrm->out_finger;
 439
 440   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 441     {
 442       /*
 443        * this case should almost never happen so the code is
 444        * inefficient
 445        */
 446       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 447       rstrm->frag_sent = TRUE;
 448       if (!flush_out (rstrm, FALSE))
 449         return FALSE;
 450       dest_ip = (int32_t *) rstrm->out_finger;
 451       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 452     }
 453   *dest_ip = htonl (*ip);
 454   return TRUE;
 455 }
 456
 457 /*
 458  * Exported routines to manage xdr records
 459  */
 460
 461 /*
 462  * Before reading (deserializing from the stream, one should always call
 463  * this procedure to guarantee proper record alignment.
 464  */
 465 bool_t
 466 xdrrec_skiprecord (XDR *xdrs)
 467 {
 468   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 469
 470   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 471     {
 472       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 473         return FALSE;
 474       rstrm->fbtbc = 0;
 475       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 476         return FALSE;
 477     }
 478   rstrm->last_frag = FALSE;
 479   return TRUE;
 480 }
 481 libc_hidden_nolink_sunrpc (xdrrec_skiprecord, GLIBC_2_0)
 482
 483 /*
 484  * Lookahead function.
 485  * Returns TRUE iff there is no more input in the buffer
 486  * after consuming the rest of the current record.
 487  */
 488 bool_t
 489 xdrrec_eof (XDR *xdrs)
 490 {
 491   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 492
 493   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 494     {
 495       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 496         return TRUE;
 497       rstrm->fbtbc = 0;
 498       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 499         return TRUE;
 500     }
 501   if (rstrm->in_finger == rstrm->in_boundry)
 502     return TRUE;
 503   return FALSE;
 504 }
 505 libc_hidden_nolink_sunrpc (xdrrec_eof, GLIBC_2_0)
 506
 507 /*
 508  * The client must tell the package when an end-of-record has occurred.
 509  * The second parameter tells whether the record should be flushed to the
 510  * (output) tcp stream.  (This lets the package support batched or
 511  * pipelined procedure calls.)  TRUE => immediate flush to tcp connection.
 512  */
 513 bool_t
 514 xdrrec_endofrecord (XDR *xdrs, bool_t sendnow)
 515 {
 516   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 517   u_long len;           /* fragment length */
 518
 519   if (sendnow || rstrm->frag_sent
 520       || rstrm->out_finger + BYTES_PER_XDR_UNIT >= rstrm->out_boundry)
 521     {
 522       rstrm->frag_sent = FALSE;
 523       return flush_out (rstrm, TRUE);
 524     }
 525   len = (rstrm->out_finger - (char *) rstrm->frag_header
 526          - BYTES_PER_XDR_UNIT);
 527   *rstrm->frag_header = htonl ((u_long) len | LAST_FRAG);
 528   rstrm->frag_header = (u_int32_t *) rstrm->out_finger;
 529   rstrm->out_finger += BYTES_PER_XDR_UNIT;
 530   return TRUE;
 531 }
 532 libc_hidden_nolink_sunrpc (xdrrec_endofrecord, GLIBC_2_0)
 533
 534
 535 /*
 536  * Internal useful routines
 537  */
 538 static bool_t
 539 internal_function
 540 flush_out (RECSTREAM *rstrm, bool_t eor)
 541 {
 542   u_long eormask = (eor == TRUE) ? LAST_FRAG : 0;
 543   u_long len = (rstrm->out_finger - (char *) rstrm->frag_header
 544                 - BYTES_PER_XDR_UNIT);
 545
 546   *rstrm->frag_header = htonl (len | eormask);
 547   len = rstrm->out_finger - rstrm->out_base;
 548   if ((*(rstrm->writeit)) (rstrm->tcp_handle, rstrm->out_base, (int) len)
 549       != (int) len)
 550     return FALSE;
 551   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 552   rstrm->out_finger = (caddr_t) rstrm->out_base + BYTES_PER_XDR_UNIT;
 553   return TRUE;
 554 }
 555
 556 static bool_t   /* knows nothing about records!  Only about input buffers */
 557 fill_input_buf (RECSTREAM *rstrm)
 558 {
 559   caddr_t where;
 560   size_t i;
 561   int len;
 562
 563   where = rstrm->in_base;
 564   i = (size_t) rstrm->in_boundry % BYTES_PER_XDR_UNIT;
 565   where += i;
 566   len = rstrm->in_size - i;
 567   if ((len = (*(rstrm->readit)) (rstrm->tcp_handle, where, len)) == -1)
 568     return FALSE;
 569   rstrm->in_finger = where;
 570   where += len;
 571   rstrm->in_boundry = where;
 572   return TRUE;
 573 }
 574
 575 static bool_t   /* knows nothing about records!  Only about input buffers */
 576 internal_function
 577 get_input_bytes (RECSTREAM *rstrm, caddr_t addr, int len)
 578 {
 579   int current;
 580
 581   while (len > 0)
 582     {
 583       current = rstrm->in_boundry - rstrm->in_finger;
 584       if (current == 0)
 585         {
 586           if (!fill_input_buf (rstrm))
 587             return FALSE;
 588           continue;
 589         }
 590       current = (len < current) ? len : current;
 591       memcpy (addr, rstrm->in_finger, current);
 592       rstrm->in_finger += current;
 593       addr += current;
 594       len -= current;
 595     }
 596   return TRUE;
 597 }
 598
 599 static bool_t /* next two bytes of the input stream are treated as a header */
 600 internal_function
 601 set_input_fragment (RECSTREAM *rstrm)
 602 {
 603   uint32_t header;
 604
 605   if (! get_input_bytes (rstrm, (caddr_t)&header, BYTES_PER_XDR_UNIT))
 606     return FALSE;
 607   header = ntohl (header);
 608   rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
 609   /*
 610    * Sanity check. Try not to accept wildly incorrect fragment
 611    * sizes. Unfortunately, only a size of zero can be identified as
 612    * 'wildely incorrect', and this only, if it is not the last
 613    * fragment of a message. Ridiculously large fragment sizes may look
 614    * wrong, but we don't have any way to be certain that they aren't
 615    * what the client actually intended to send us. Many existing RPC
 616    * implementations may sent a fragment of size zero as the last
 617    * fragment of a message.
 618    */
 619   if (header == 0)
 620     return FALSE;
 621   rstrm->fbtbc = header & ~LAST_FRAG;
 622   return TRUE;
 623 }
 624
 625 static bool_t   /* consumes input bytes; knows nothing about records! */
 626 internal_function
 627 skip_input_bytes (RECSTREAM *rstrm, long cnt)
 628 {
 629   int current;
 630
 631   while (cnt > 0)
 632     {
 633       current = rstrm->in_boundry - rstrm->in_finger;
 634       if (current == 0)
 635         {
 636           if (!fill_input_buf (rstrm))
 637             return FALSE;
 638           continue;
 639         }
 640       current = (cnt < current) ? cnt : current;
 641       rstrm->in_finger += current;
 642       cnt -= current;
 643     }
 644   return TRUE;
 645 }
 646
 647 static u_int
 648 internal_function
 649 fix_buf_size (u_int s)
 650 {
 651   if (s < 100)
 652     s = 4000;
 653   return RNDUP (s);
 654 }