sunrpc/xdr_rec.c

   1 /*
   2  * Sun RPC is a product of Sun Microsystems, Inc. and is provided for
   3  * unrestricted use provided that this legend is included on all tape
   4  * media and as a part of the software program in whole or part.  Users
   5  * may copy or modify Sun RPC without charge, but are not authorized
   6  * to license or distribute it to anyone else except as part of a product or
   7  * program developed by the user.
   8  *
   9  * SUN RPC IS PROVIDED AS IS WITH NO WARRANTIES OF ANY KIND INCLUDING THE
  10  * WARRANTIES OF DESIGN, MERCHANTIBILITY AND FITNESS FOR A PARTICULAR
  11  * PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE OR TRADE PRACTICE.
  12  *
  13  * Sun RPC is provided with no support and without any obligation on the
  14  * part of Sun Microsystems, Inc. to assist in its use, correction,
  15  * modification or enhancement.
  16  *
  17  * SUN MICROSYSTEMS, INC. SHALL HAVE NO LIABILITY WITH RESPECT TO THE
  18  * INFRINGEMENT OF COPYRIGHTS, TRADE SECRETS OR ANY PATENTS BY SUN RPC
  19  * OR ANY PART THEREOF.
  20  *
  21  * In no event will Sun Microsystems, Inc. be liable for any lost revenue
  22  * or profits or other special, indirect and consequential damages, even if
  23  * Sun has been advised of the possibility of such damages.
  24  *
  25  * Sun Microsystems, Inc.
  26  * 2550 Garcia Avenue
  27  * Mountain View, California  94043
  28  */
  29
  30 /*
  31  * xdr_rec.c, Implements TCP/IP based XDR streams with a "record marking"
  32  * layer above tcp (for rpc's use).
  33  *
  34  * Copyright (C) 1984, Sun Microsystems, Inc.
  35  *
  36  * These routines interface XDRSTREAMS to a tcp/ip connection.
  37  * There is a record marking layer between the xdr stream
  38  * and the tcp transport level.  A record is composed on one or more
  39  * record fragments.  A record fragment is a thirty-two bit header followed
  40  * by n bytes of data, where n is contained in the header.  The header
  41  * is represented as a htonl(u_long).  The high order bit encodes
  42  * whether or not the fragment is the last fragment of the record
  43  * (1 => fragment is last, 0 => more fragments to follow.
  44  * The other 31 bits encode the byte length of the fragment.
  45  */
  46
  47 #include <stdio.h>
  48 #include <string.h>
  49 #include <unistd.h>
  50 #include <rpc/rpc.h>
  51 #include <libintl.h>
  52
  53 #ifdef USE_IN_LIBIO
  54 # include <wchar.h>
  55 # include <libio/iolibio.h>
  56 #endif
  57
  58 static bool_t xdrrec_getlong (XDR *, long *);
  59 static bool_t xdrrec_putlong (XDR *, const long *);
  60 static bool_t xdrrec_getbytes (XDR *, caddr_t, u_int);
  61 static bool_t xdrrec_putbytes (XDR *, const char *, u_int);
  62 static u_int xdrrec_getpos (const XDR *);
  63 static bool_t xdrrec_setpos (XDR *, u_int);
  64 static int32_t *xdrrec_inline (XDR *, u_int);
  65 static void xdrrec_destroy (XDR *);
  66 static bool_t xdrrec_getint32 (XDR *, int32_t *);
  67 static bool_t xdrrec_putint32 (XDR *, const int32_t *);
  68
  69 static const struct xdr_ops xdrrec_ops = {
  70   xdrrec_getlong,
  71   xdrrec_putlong,
  72   xdrrec_getbytes,
  73   xdrrec_putbytes,
  74   xdrrec_getpos,
  75   xdrrec_setpos,
  76   xdrrec_inline,
  77   xdrrec_destroy,
  78   xdrrec_getint32,
  79   xdrrec_putint32
  80 };
  81
  82 /*
  83  * A record is composed of one or more record fragments.
  84  * A record fragment is a two-byte header followed by zero to
  85  * 2**32-1 bytes.  The header is treated as a long unsigned and is
  86  * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
  87  * are a byte count of the fragment.  The highest order bit is a boolean:
  88  * 1 => this fragment is the last fragment of the record,
  89  * 0 => this fragment is followed by more fragment(s).
  90  *
  91  * The fragment/record machinery is not general;  it is constructed to
  92  * meet the needs of xdr and rpc based on tcp.
  93  */
  94
  95 #define LAST_FRAG (1UL << 31)
  96
  97 typedef struct rec_strm
  98   {
  99     caddr_t tcp_handle;
 100     caddr_t the_buffer;
 101     /*
 102      * out-going bits
 103      */
 104     int (*writeit) (char *, char *, int);
 105     caddr_t out_base;           /* output buffer (points to frag header) */
 106     caddr_t out_finger;         /* next output position */
 107     caddr_t out_boundry;        /* data cannot up to this address */
 108     u_int32_t *frag_header;     /* beginning of curren fragment */
 109     bool_t frag_sent;           /* true if buffer sent in middle of record */
 110     /*
 111      * in-coming bits
 112      */
 113     int (*readit) (char *, char *, int);
 114     u_long in_size;             /* fixed size of the input buffer */
 115     caddr_t in_base;
 116     caddr_t in_finger;          /* location of next byte to be had */
 117     caddr_t in_boundry;         /* can read up to this location */
 118     long fbtbc;                 /* fragment bytes to be consumed */
 119     bool_t last_frag;
 120     u_int sendsize;
 121     u_int recvsize;
 122   }
 123 RECSTREAM;
 124
 125 static u_int fix_buf_size (u_int) internal_function;
 126 static bool_t skip_input_bytes (RECSTREAM *, long) internal_function;
 127 static bool_t flush_out (RECSTREAM *, bool_t) internal_function;
 128 static bool_t set_input_fragment (RECSTREAM *) internal_function;
 129 static bool_t get_input_bytes (RECSTREAM *, caddr_t, int) internal_function;
 130
 131 /*
 132  * Create an xdr handle for xdrrec
 133  * xdrrec_create fills in xdrs.  Sendsize and recvsize are
 134  * send and recv buffer sizes (0 => use default).
 135  * tcp_handle is an opaque handle that is passed as the first parameter to
 136  * the procedures readit and writeit.  Readit and writeit are read and
 137  * write respectively.   They are like the system
 138  * calls expect that they take an opaque handle rather than an fd.
 139  */
 140 void
 141 xdrrec_create (XDR *xdrs, u_int sendsize,
 142                u_int recvsize, caddr_t tcp_handle,
 143                int (*readit) (char *, char *, int),
 144                int (*writeit) (char *, char *, int))
 145 {
 146   RECSTREAM *rstrm = (RECSTREAM *) mem_alloc (sizeof (RECSTREAM));
 147   caddr_t tmp;
 148   char *buf;
 149
 150   sendsize = fix_buf_size (sendsize);
 151   recvsize = fix_buf_size (recvsize);
 152   buf = mem_alloc (sendsize + recvsize + BYTES_PER_XDR_UNIT);
 153
 154   if (rstrm == NULL || buf == NULL)
 155     {
 156 #ifdef USE_IN_LIBIO
 157       if (_IO_fwide (stderr, 0) > 0)
 158         (void) __fwprintf (stderr, L"%s", _("xdrrec_create: out of memory\n"));
 159       else
 160 #endif
 161         (void) fputs (_("xdrrec_create: out of memory\n"), stderr);
 162       mem_free (rstrm, sizeof (RECSTREAM));
 163       mem_free (buf, sendsize + recvsize + BYTES_PER_XDR_UNIT);
 164       /*
 165        *  This is bad.  Should rework xdrrec_create to
 166        *  return a handle, and in this case return NULL
 167        */
 168       return;
 169     }
 170   /*
 171    * adjust sizes and allocate buffer quad byte aligned
 172    */
 173   rstrm->sendsize = sendsize;
 174   rstrm->recvsize = recvsize;
 175   rstrm->the_buffer = buf;
 176   tmp = rstrm->the_buffer;
 177   if ((size_t)tmp % BYTES_PER_XDR_UNIT)
 178     tmp += BYTES_PER_XDR_UNIT - (size_t)tmp % BYTES_PER_XDR_UNIT;
 179   rstrm->out_base = tmp;
 180   rstrm->in_base = tmp + sendsize;
 181   /*
 182    * now the rest ...
 183    */
 184   /* We have to add the const since the `struct xdr_ops' in `struct XDR'
 185      is not `const'.  */
 186   xdrs->x_ops = (struct xdr_ops *) &xdrrec_ops;
 187   xdrs->x_private = (caddr_t) rstrm;
 188   rstrm->tcp_handle = tcp_handle;
 189   rstrm->readit = readit;
 190   rstrm->writeit = writeit;
 191   rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
 192   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 193   rstrm->out_finger += 4;
 194   rstrm->out_boundry += sendsize;
 195   rstrm->frag_sent = FALSE;
 196   rstrm->in_size = recvsize;
 197   rstrm->in_boundry = rstrm->in_base;
 198   rstrm->in_finger = (rstrm->in_boundry += recvsize);
 199   rstrm->fbtbc = 0;
 200   rstrm->last_frag = TRUE;
 201 }
 202 INTDEF(xdrrec_create)
 203
 204
 205 /*
 206  * The routines defined below are the xdr ops which will go into the
 207  * xdr handle filled in by xdrrec_create.
 208  */
 209
 210 static bool_t
 211 xdrrec_getlong (XDR *xdrs, long *lp)
 212 {
 213   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 214   int32_t *buflp = (int32_t *) rstrm->in_finger;
 215   int32_t mylong;
 216
 217   /* first try the inline, fast case */
 218   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 219       rstrm->in_boundry - (char *) buflp >= BYTES_PER_XDR_UNIT)
 220     {
 221       *lp = (int32_t) ntohl (*buflp);
 222       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 223       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 224     }
 225   else
 226     {
 227       if (!xdrrec_getbytes (xdrs, (caddr_t) & mylong,
 228                             BYTES_PER_XDR_UNIT))
 229         return FALSE;
 230       *lp = (int32_t) ntohl (mylong);
 231     }
 232   return TRUE;
 233 }
 234
 235 static bool_t
 236 xdrrec_putlong (XDR *xdrs, const long *lp)
 237 {
 238   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 239   int32_t *dest_lp = (int32_t *) rstrm->out_finger;
 240
 241   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 242     {
 243       /*
 244        * this case should almost never happen so the code is
 245        * inefficient
 246        */
 247       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 248       rstrm->frag_sent = TRUE;
 249       if (!flush_out (rstrm, FALSE))
 250         return FALSE;
 251       dest_lp = (int32_t *) rstrm->out_finger;
 252       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 253     }
 254   *dest_lp = htonl (*lp);
 255   return TRUE;
 256 }
 257
 258 static bool_t      /* must manage buffers, fragments, and records */
 259 xdrrec_getbytes (XDR *xdrs, caddr_t addr, u_int len)
 260 {
 261   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 262   u_int current;
 263
 264   while (len > 0)
 265     {
 266       current = rstrm->fbtbc;
 267       if (current == 0)
 268         {
 269           if (rstrm->last_frag)
 270             return FALSE;
 271           if (!set_input_fragment (rstrm))
 272             return FALSE;
 273           continue;
 274         }
 275       current = (len < current) ? len : current;
 276       if (!get_input_bytes (rstrm, addr, current))
 277         return FALSE;
 278       addr += current;
 279       rstrm->fbtbc -= current;
 280       len -= current;
 281     }
 282   return TRUE;
 283 }
 284
 285 static bool_t
 286 xdrrec_putbytes (XDR *xdrs, const char *addr, u_int len)
 287 {
 288   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 289   u_int current;
 290
 291   while (len > 0)
 292     {
 293       current = rstrm->out_boundry - rstrm->out_finger;
 294       current = (len < current) ? len : current;
 295       memcpy (rstrm->out_finger, addr, current);
 296       rstrm->out_finger += current;
 297       addr += current;
 298       len -= current;
 299       if (rstrm->out_finger == rstrm->out_boundry && len > 0)
 300         {
 301           rstrm->frag_sent = TRUE;
 302           if (!flush_out (rstrm, FALSE))
 303             return FALSE;
 304         }
 305     }
 306   return TRUE;
 307 }
 308
 309 static u_int
 310 xdrrec_getpos (const XDR *xdrs)
 311 {
 312   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 313   long pos;
 314
 315   pos = __lseek ((int) (long) rstrm->tcp_handle, (long) 0, 1);
 316   if (pos != -1)
 317     switch (xdrs->x_op)
 318       {
 319
 320       case XDR_ENCODE:
 321         pos += rstrm->out_finger - rstrm->out_base;
 322         break;
 323
 324       case XDR_DECODE:
 325         pos -= rstrm->in_boundry - rstrm->in_finger;
 326         break;
 327
 328       default:
 329         pos = (u_int) - 1;
 330         break;
 331       }
 332   return (u_int) pos;
 333 }
 334
 335 static bool_t
 336 xdrrec_setpos (XDR *xdrs, u_int pos)
 337 {
 338   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 339   u_int currpos = xdrrec_getpos (xdrs);
 340   int delta = currpos - pos;
 341   caddr_t newpos;
 342
 343   if ((int) currpos != -1)
 344     switch (xdrs->x_op)
 345       {
 346
 347       case XDR_ENCODE:
 348         newpos = rstrm->out_finger - delta;
 349         if (newpos > (caddr_t) rstrm->frag_header &&
 350             newpos < rstrm->out_boundry)
 351           {
 352             rstrm->out_finger = newpos;
 353             return TRUE;
 354           }
 355         break;
 356
 357       case XDR_DECODE:
 358         newpos = rstrm->in_finger - delta;
 359         if ((delta < (int) (rstrm->fbtbc)) &&
 360             (newpos <= rstrm->in_boundry) &&
 361             (newpos >= rstrm->in_base))
 362           {
 363             rstrm->in_finger = newpos;
 364             rstrm->fbtbc -= delta;
 365             return TRUE;
 366           }
 367         break;
 368
 369       default:
 370         break;
 371       }
 372   return FALSE;
 373 }
 374
 375 static int32_t *
 376 xdrrec_inline (XDR *xdrs, u_int len)
 377 {
 378   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 379   int32_t *buf = NULL;
 380
 381   switch (xdrs->x_op)
 382     {
 383
 384     case XDR_ENCODE:
 385       if ((rstrm->out_finger + len) <= rstrm->out_boundry)
 386         {
 387           buf = (int32_t *) rstrm->out_finger;
 388           rstrm->out_finger += len;
 389         }
 390       break;
 391
 392     case XDR_DECODE:
 393       if ((len <= rstrm->fbtbc) &&
 394           ((rstrm->in_finger + len) <= rstrm->in_boundry))
 395         {
 396           buf = (int32_t *) rstrm->in_finger;
 397           rstrm->fbtbc -= len;
 398           rstrm->in_finger += len;
 399         }
 400       break;
 401
 402     default:
 403       break;
 404     }
 405   return buf;
 406 }
 407
 408 static void
 409 xdrrec_destroy (XDR *xdrs)
 410 {
 411   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 412
 413   mem_free (rstrm->the_buffer,
 414             rstrm->sendsize + rstrm->recvsize + BYTES_PER_XDR_UNIT);
 415   mem_free ((caddr_t) rstrm, sizeof (RECSTREAM));
 416 }
 417
 418 static bool_t
 419 xdrrec_getint32 (XDR *xdrs, int32_t *ip)
 420 {
 421   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 422   int32_t *bufip = (int32_t *) rstrm->in_finger;
 423   int32_t mylong;
 424
 425   /* first try the inline, fast case */
 426   if (rstrm->fbtbc >= BYTES_PER_XDR_UNIT &&
 427       rstrm->in_boundry - (char *) bufip >= BYTES_PER_XDR_UNIT)
 428     {
 429       *ip = ntohl (*bufip);
 430       rstrm->fbtbc -= BYTES_PER_XDR_UNIT;
 431       rstrm->in_finger += BYTES_PER_XDR_UNIT;
 432     }
 433   else
 434     {
 435       if (!xdrrec_getbytes (xdrs, (caddr_t) &mylong,
 436                             BYTES_PER_XDR_UNIT))
 437         return FALSE;
 438       *ip = ntohl (mylong);
 439     }
 440   return TRUE;
 441 }
 442
 443 static bool_t
 444 xdrrec_putint32 (XDR *xdrs, const int32_t *ip)
 445 {
 446   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 447   int32_t *dest_ip = (int32_t *) rstrm->out_finger;
 448
 449   if ((rstrm->out_finger += BYTES_PER_XDR_UNIT) > rstrm->out_boundry)
 450     {
 451       /*
 452        * this case should almost never happen so the code is
 453        * inefficient
 454        */
 455       rstrm->out_finger -= BYTES_PER_XDR_UNIT;
 456       rstrm->frag_sent = TRUE;
 457       if (!flush_out (rstrm, FALSE))
 458         return FALSE;
 459       dest_ip = (int32_t *) rstrm->out_finger;
 460       rstrm->out_finger += BYTES_PER_XDR_UNIT;
 461     }
 462   *dest_ip = htonl (*ip);
 463   return TRUE;
 464 }
 465
 466 /*
 467  * Exported routines to manage xdr records
 468  */
 469
 470 /*
 471  * Before reading (deserializing from the stream, one should always call
 472  * this procedure to guarantee proper record alignment.
 473  */
 474 bool_t
 475 xdrrec_skiprecord (XDR *xdrs)
 476 {
 477   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 478
 479   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 480     {
 481       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 482         return FALSE;
 483       rstrm->fbtbc = 0;
 484       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 485         return FALSE;
 486     }
 487   rstrm->last_frag = FALSE;
 488   return TRUE;
 489 }
 490 INTDEF(xdrrec_skiprecord)
 491
 492 /*
 493  * Lookahead function.
 494  * Returns TRUE iff there is no more input in the buffer
 495  * after consuming the rest of the current record.
 496  */
 497 bool_t
 498 xdrrec_eof (XDR *xdrs)
 499 {
 500   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 501
 502   while (rstrm->fbtbc > 0 || (!rstrm->last_frag))
 503     {
 504       if (!skip_input_bytes (rstrm, rstrm->fbtbc))
 505         return TRUE;
 506       rstrm->fbtbc = 0;
 507       if ((!rstrm->last_frag) && (!set_input_fragment (rstrm)))
 508         return TRUE;
 509     }
 510   if (rstrm->in_finger == rstrm->in_boundry)
 511     return TRUE;
 512   return FALSE;
 513 }
 514 INTDEF(xdrrec_eof)
 515
 516 /*
 517  * The client must tell the package when an end-of-record has occurred.
 518  * The second parameter tells whether the record should be flushed to the
 519  * (output) tcp stream.  (This lets the package support batched or
 520  * pipelined procedure calls.)  TRUE => immediate flush to tcp connection.
 521  */
 522 bool_t
 523 xdrrec_endofrecord (XDR *xdrs, bool_t sendnow)
 524 {
 525   RECSTREAM *rstrm = (RECSTREAM *) xdrs->x_private;
 526   u_long len;           /* fragment length */
 527
 528   if (sendnow || rstrm->frag_sent
 529       || rstrm->out_finger + BYTES_PER_XDR_UNIT >= rstrm->out_boundry)
 530     {
 531       rstrm->frag_sent = FALSE;
 532       return flush_out (rstrm, TRUE);
 533     }
 534   len = (rstrm->out_finger - (char *) rstrm->frag_header
 535          - BYTES_PER_XDR_UNIT);
 536   *rstrm->frag_header = htonl ((u_long) len | LAST_FRAG);
 537   rstrm->frag_header = (u_int32_t *) rstrm->out_finger;
 538   rstrm->out_finger += BYTES_PER_XDR_UNIT;
 539   return TRUE;
 540 }
 541 INTDEF(xdrrec_endofrecord)
 542
 543
 544 /*
 545  * Internal useful routines
 546  */
 547 static bool_t
 548 internal_function
 549 flush_out (RECSTREAM *rstrm, bool_t eor)
 550 {
 551   u_long eormask = (eor == TRUE) ? LAST_FRAG : 0;
 552   u_long len = (rstrm->out_finger - (char *) rstrm->frag_header
 553                 - BYTES_PER_XDR_UNIT);
 554
 555   *rstrm->frag_header = htonl (len | eormask);
 556   len = rstrm->out_finger - rstrm->out_base;
 557   if ((*(rstrm->writeit)) (rstrm->tcp_handle, rstrm->out_base, (int) len)
 558       != (int) len)
 559     return FALSE;
 560   rstrm->frag_header = (u_int32_t *) rstrm->out_base;
 561   rstrm->out_finger = (caddr_t) rstrm->out_base + BYTES_PER_XDR_UNIT;
 562   return TRUE;
 563 }
 564
 565 static bool_t   /* knows nothing about records!  Only about input buffers */
 566 fill_input_buf (RECSTREAM *rstrm)
 567 {
 568   caddr_t where;
 569   size_t i;
 570   int len;
 571
 572   where = rstrm->in_base;
 573   i = (size_t) rstrm->in_boundry % BYTES_PER_XDR_UNIT;
 574   where += i;
 575   len = rstrm->in_size - i;
 576   if ((len = (*(rstrm->readit)) (rstrm->tcp_handle, where, len)) == -1)
 577     return FALSE;
 578   rstrm->in_finger = where;
 579   where += len;
 580   rstrm->in_boundry = where;
 581   return TRUE;
 582 }
 583
 584 static bool_t   /* knows nothing about records!  Only about input buffers */
 585 internal_function
 586 get_input_bytes (RECSTREAM *rstrm, caddr_t addr, int len)
 587 {
 588   int current;
 589
 590   while (len > 0)
 591     {
 592       current = rstrm->in_boundry - rstrm->in_finger;
 593       if (current == 0)
 594         {
 595           if (!fill_input_buf (rstrm))
 596             return FALSE;
 597           continue;
 598         }
 599       current = (len < current) ? len : current;
 600       memcpy (addr, rstrm->in_finger, current);
 601       rstrm->in_finger += current;
 602       addr += current;
 603       len -= current;
 604     }
 605   return TRUE;
 606 }
 607
 608 static bool_t /* next two bytes of the input stream are treated as a header */
 609 internal_function
 610 set_input_fragment (RECSTREAM *rstrm)
 611 {
 612   uint32_t header;
 613
 614   if (! get_input_bytes (rstrm, (caddr_t)&header, BYTES_PER_XDR_UNIT))
 615     return FALSE;
 616   header = ntohl (header);
 617   rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
 618   /*
 619    * Sanity check. Try not to accept wildly incorrect fragment
 620    * sizes. Unfortunately, only a size of zero can be identified as
 621    * 'wildely incorrect', and this only, if it is not the last
 622    * fragment of a message. Ridiculously large fragment sizes may look
 623    * wrong, but we don't have any way to be certain that they aren't
 624    * what the client actually intended to send us. Many existing RPC
 625    * implementations may sent a fragment of size zero as the last
 626    * fragment of a message.
 627    */
 628   if (header == 0)
 629     return FALSE;
 630   rstrm->fbtbc = header & ~LAST_FRAG;
 631   return TRUE;
 632 }
 633
 634 static bool_t   /* consumes input bytes; knows nothing about records! */
 635 internal_function
 636 skip_input_bytes (RECSTREAM *rstrm, long cnt)
 637 {
 638   int current;
 639
 640   while (cnt > 0)
 641     {
 642       current = rstrm->in_boundry - rstrm->in_finger;
 643       if (current == 0)
 644         {
 645           if (!fill_input_buf (rstrm))
 646             return FALSE;
 647           continue;
 648         }
 649       current = (cnt < current) ? cnt : current;
 650       rstrm->in_finger += current;
 651       cnt -= current;
 652     }
 653   return TRUE;
 654 }
 655
 656 static u_int
 657 internal_function
 658 fix_buf_size (u_int s)
 659 {
 660   if (s < 100)
 661     s = 4000;
 662   return RNDUP (s);
 663 }