xref: /dragonfly/lib/libc/xdr/xdr_rec.c (revision de78d61c)
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  * @(#)xdr_rec.c 1.21 87/08/11 Copyr 1984 Sun Micro
30  * @(#)xdr_rec.c	2.2 88/08/01 4.0 RPCSRC
31  * $NetBSD: xdr_rec.c,v 1.18 2000/07/06 03:10:35 christos Exp $
32  * $FreeBSD: src/lib/libc/xdr/xdr_rec.c,v 1.22 2008/03/30 09:35:04 dfr Exp $
33  */
34 
35 /*
36  * xdr_rec.c, Implements TCP/IP based XDR streams with a "record marking"
37  * layer above tcp (for rpc's use).
38  *
39  * Copyright (C) 1984, Sun Microsystems, Inc.
40  *
41  * These routines interface XDRSTREAMS to a tcp/ip connection.
42  * There is a record marking layer between the xdr stream
43  * and the tcp transport level.  A record is composed on one or more
44  * record fragments.  A record fragment is a thirty-two bit header followed
45  * by n bytes of data, where n is contained in the header.  The header
46  * is represented as a htonl(u_long).  Thegh order bit encodes
47  * whether or not the fragment is the last fragment of the record
48  * (1 => fragment is last, 0 => more fragments to follow.
49  * The other 31 bits encode the byte length of the fragment.
50  */
51 
52 #include "namespace.h"
53 #include <sys/types.h>
54 
55 #include <netinet/in.h>
56 
57 #include <err.h>
58 #include <stddef.h>
59 #include <stdio.h>
60 #include <stdlib.h>
61 #include <string.h>
62 #include <unistd.h>
63 
64 #include <rpc/types.h>
65 #include <rpc/xdr.h>
66 #include <rpc/auth.h>
67 #include <rpc/svc.h>
68 #include <rpc/clnt.h>
69 #include "un-namespace.h"
70 #include "rpc_com.h"
71 
72 static bool_t	xdrrec_getlong(XDR *, long *);
73 static bool_t	xdrrec_putlong(XDR *, const long *);
74 static bool_t	xdrrec_getbytes(XDR *, char *, u_int);
75 
76 static bool_t	xdrrec_putbytes(XDR *, const char *, u_int);
77 static u_int	xdrrec_getpos(XDR *);
78 static bool_t	xdrrec_setpos(XDR *, u_int);
79 static int32_t *xdrrec_inline(XDR *, u_int);
80 static void	xdrrec_destroy(XDR *);
81 
82 static const struct  xdr_ops xdrrec_ops = {
83 	xdrrec_getlong,
84 	xdrrec_putlong,
85 	xdrrec_getbytes,
86 	xdrrec_putbytes,
87 	xdrrec_getpos,
88 	xdrrec_setpos,
89 	xdrrec_inline,
90 	xdrrec_destroy,
91 	NULL
92 };
93 
94 /*
95  * A record is composed of one or more record fragments.
96  * A record fragment is a four-byte header followed by zero to
97  * 2**32-1 bytes.  The header is treated as an unsigned long and is
98  * encode/decoded to the network via htonl/ntohl.  The low order 31 bits
99  * are a byte count of the fragment.  The highest order bit is a boolean:
100  * 1 => this fragment is the last fragment of the record,
101  * 0 => this fragment is followed by more fragment(s).
102  *
103  * The fragment/record machinery is not general;  it is constructed to
104  * meet the needs of xdr and rpc based on tcp.
105  */
106 
107 #define LAST_FRAG ((uint32_t)(1 << 31))
108 
109 typedef struct rec_strm {
110 	char *tcp_handle;
111 	/*
112 	 * out-going bits
113 	 */
114 	int (*writeit)(void *, void *, int);
115 	char *out_base;	/* output buffer (points to frag header) */
116 	char *out_finger;	/* next output position */
117 	char *out_boundry;	/* data cannot up to this address */
118 	uint32_t *frag_header;	/* beginning of current fragment */
119 	bool_t frag_sent;	/* true if buffer sent in middle of record */
120 	/*
121 	 * in-coming bits
122 	 */
123 	int (*readit)(void *, void *, int);
124 	u_long in_size;	/* fixed size of the input buffer */
125 	char *in_base;
126 	char *in_finger;	/* location of next byte to be had */
127 	char *in_boundry;	/* can read up to this location */
128 	long fbtbc;		/* fragment bytes to be consumed */
129 	bool_t last_frag;
130 	u_int sendsize;
131 	u_int recvsize;
132 
133 	bool_t nonblock;
134 	bool_t in_haveheader;
135 	uint32_t in_header;
136 	char *in_hdrp;
137 	int in_hdrlen;
138 	int in_reclen;
139 	int in_received;
140 	int in_maxrec;
141 } RECSTREAM;
142 
143 static u_int	fix_buf_size(u_int);
144 static bool_t	flush_out(RECSTREAM *, bool_t);
145 static bool_t	fill_input_buf(RECSTREAM *);
146 static bool_t	get_input_bytes(RECSTREAM *, char *, int);
147 static bool_t	set_input_fragment(RECSTREAM *);
148 static bool_t	skip_input_bytes(RECSTREAM *, long);
149 static bool_t	realloc_stream(RECSTREAM *, int);
150 
151 /*
152  * Create an xdr handle for xdrrec
153  * xdrrec_create fills in xdrs.  Sendsize and recvsize are
154  * send and recv buffer sizes (0 => use default).
155  * tcp_handle is an opaque handle that is passed as the first parameter to
156  * the procedures readit and writeit.  Readit and writeit are read and
157  * write respectively.   They are like the system
158  * calls expect that they take an opaque handle rather than an fd.
159  *
160  * Parameters:
161  *     readit:	like read, but pass it a tcp_handle, not sock
162  *     writeit:	lite write, but pass it a tcp_handle, not sock
163  */
164 void
165 xdrrec_create(XDR *xdrs, u_int sendsize, u_int recvsize, void *tcp_handle,
166 	      int (*readit)(void *, void *, int),
167 	      int (*writeit)(void *, void *, int))
168 {
169 	RECSTREAM *rstrm = mem_alloc(sizeof(RECSTREAM));
170 
171 	if (rstrm == NULL) {
172 		warnx("xdrrec_create: out of memory");
173 		/*
174 		 *  This is bad.  Should rework xdrrec_create to
175 		 *  return a handle, and in this case return NULL
176 		 */
177 		return;
178 	}
179 	rstrm->sendsize = sendsize = fix_buf_size(sendsize);
180 	rstrm->out_base = mem_alloc(rstrm->sendsize);
181 	if (rstrm->out_base == NULL) {
182 		warnx("xdrrec_create: out of memory");
183 		mem_free(rstrm, sizeof(RECSTREAM));
184 		return;
185 	}
186 	rstrm->recvsize = recvsize = fix_buf_size(recvsize);
187 	rstrm->in_base = mem_alloc(recvsize);
188 	if (rstrm->in_base == NULL) {
189 		warnx("xdrrec_create: out of memory");
190 		mem_free(rstrm->out_base, sendsize);
191 		mem_free(rstrm, sizeof(RECSTREAM));
192 		return;
193 	}
194 	/*
195 	 * now the rest ...
196 	 */
197 	xdrs->x_ops = &xdrrec_ops;
198 	xdrs->x_private = rstrm;
199 	rstrm->tcp_handle = tcp_handle;
200 	rstrm->readit = readit;
201 	rstrm->writeit = writeit;
202 	rstrm->out_finger = rstrm->out_boundry = rstrm->out_base;
203 	rstrm->frag_header = (uint32_t *)(void *)rstrm->out_base;
204 	rstrm->out_finger += sizeof(uint32_t);
205 	rstrm->out_boundry += sendsize;
206 	rstrm->frag_sent = FALSE;
207 	rstrm->in_size = recvsize;
208 	rstrm->in_boundry = rstrm->in_base;
209 	rstrm->in_finger = (rstrm->in_boundry += recvsize);
210 	rstrm->fbtbc = 0;
211 	rstrm->last_frag = TRUE;
212 	rstrm->in_haveheader = FALSE;
213 	rstrm->in_hdrlen = 0;
214 	rstrm->in_hdrp = (char *)(void *)&rstrm->in_header;
215 	rstrm->nonblock = FALSE;
216 	rstrm->in_reclen = 0;
217 	rstrm->in_received = 0;
218 }
219 
220 
221 /*
222  * The routines defined below are the xdr ops which will go into the
223  * xdr handle filled in by xdrrec_create.
224  */
225 
226 static bool_t
227 xdrrec_getlong(XDR *xdrs, long *lp)
228 {
229 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
230 	int32_t *buflp = (int32_t *)(void *)(rstrm->in_finger);
231 	int32_t mylong;
232 
233 	/* first try the inline, fast case */
234 	if ((rstrm->fbtbc >= sizeof(int32_t)) &&
235 		(((long)rstrm->in_boundry - (long)buflp) >= sizeof(int32_t))) {
236 		*lp = (long)ntohl((uint32_t)(*buflp));
237 		rstrm->fbtbc -= sizeof(int32_t);
238 		rstrm->in_finger += sizeof(int32_t);
239 	} else {
240 		if (! xdrrec_getbytes(xdrs, (char *)(void *)&mylong,
241 		    sizeof(int32_t)))
242 			return (FALSE);
243 		*lp = (long)ntohl((uint32_t)mylong);
244 	}
245 	return (TRUE);
246 }
247 
248 static bool_t
249 xdrrec_putlong(XDR *xdrs, const long *lp)
250 {
251 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
252 	int32_t *dest_lp = ((int32_t *)(void *)(rstrm->out_finger));
253 
254 	if ((rstrm->out_finger += sizeof(int32_t)) > rstrm->out_boundry) {
255 		/*
256 		 * this case should almost never happen so the code is
257 		 * inefficient
258 		 */
259 		rstrm->out_finger -= sizeof(int32_t);
260 		rstrm->frag_sent = TRUE;
261 		if (! flush_out(rstrm, FALSE))
262 			return (FALSE);
263 		dest_lp = ((int32_t *)(void *)(rstrm->out_finger));
264 		rstrm->out_finger += sizeof(int32_t);
265 	}
266 	*dest_lp = (int32_t)htonl((uint32_t)(*lp));
267 	return (TRUE);
268 }
269 
270 static bool_t  /* must manage buffers, fragments, and records */
271 xdrrec_getbytes(XDR *xdrs, char *addr, u_int len)
272 {
273 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
274 	int current;
275 
276 	while (len > 0) {
277 		current = (int)rstrm->fbtbc;
278 		if (current == 0) {
279 			if (rstrm->last_frag)
280 				return (FALSE);
281 			if (! set_input_fragment(rstrm))
282 				return (FALSE);
283 			continue;
284 		}
285 		current = (len < current) ? len : current;
286 		if (! get_input_bytes(rstrm, addr, current))
287 			return (FALSE);
288 		addr += current;
289 		rstrm->fbtbc -= current;
290 		len -= current;
291 	}
292 	return (TRUE);
293 }
294 
295 static bool_t
296 xdrrec_putbytes(XDR *xdrs, const char *addr, u_int len)
297 {
298 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
299 	size_t current;
300 
301 	while (len > 0) {
302 		current = (size_t)((u_long)rstrm->out_boundry -
303 		    (u_long)rstrm->out_finger);
304 		current = (len < current) ? len : current;
305 		memmove(rstrm->out_finger, addr, current);
306 		rstrm->out_finger += current;
307 		addr += current;
308 		len -= current;
309 		if (rstrm->out_finger == rstrm->out_boundry) {
310 			rstrm->frag_sent = TRUE;
311 			if (! flush_out(rstrm, FALSE))
312 				return (FALSE);
313 		}
314 	}
315 	return (TRUE);
316 }
317 
318 static u_int
319 xdrrec_getpos(XDR *xdrs)
320 {
321 	RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
322 	off_t pos;
323 
324 	pos = lseek((int)(u_long)rstrm->tcp_handle, (off_t)0, 1);
325 	if (pos != -1)
326 		switch (xdrs->x_op) {
327 
328 		case XDR_ENCODE:
329 			pos += rstrm->out_finger - rstrm->out_base;
330 			break;
331 
332 		case XDR_DECODE:
333 			pos -= rstrm->in_boundry - rstrm->in_finger;
334 			break;
335 
336 		default:
337 			pos = (off_t) -1;
338 			break;
339 		}
340 	return ((u_int) pos);
341 }
342 
343 static bool_t
344 xdrrec_setpos(XDR *xdrs, u_int pos)
345 {
346 	RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
347 	u_int currpos = xdrrec_getpos(xdrs);
348 	int delta = currpos - pos;
349 	char *newpos;
350 
351 	if ((int)currpos != -1)
352 		switch (xdrs->x_op) {
353 
354 		case XDR_ENCODE:
355 			newpos = rstrm->out_finger - delta;
356 			if ((newpos > (char *)(void *)(rstrm->frag_header)) &&
357 				(newpos < rstrm->out_boundry)) {
358 				rstrm->out_finger = newpos;
359 				return (TRUE);
360 			}
361 			break;
362 
363 		case XDR_DECODE:
364 			newpos = rstrm->in_finger - delta;
365 			if ((delta < (int)(rstrm->fbtbc)) &&
366 				(newpos <= rstrm->in_boundry) &&
367 				(newpos >= rstrm->in_base)) {
368 				rstrm->in_finger = newpos;
369 				rstrm->fbtbc -= delta;
370 				return (TRUE);
371 			}
372 			break;
373 
374 		case XDR_FREE:
375 			break;
376 		}
377 	return (FALSE);
378 }
379 
380 static int32_t *
381 xdrrec_inline(XDR *xdrs, u_int len)
382 {
383 	RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
384 	int32_t *buf = NULL;
385 
386 	switch (xdrs->x_op) {
387 
388 	case XDR_ENCODE:
389 		if ((rstrm->out_finger + len) <= rstrm->out_boundry) {
390 			buf = (int32_t *)(void *)rstrm->out_finger;
391 			rstrm->out_finger += len;
392 		}
393 		break;
394 
395 	case XDR_DECODE:
396 		if ((len <= rstrm->fbtbc) &&
397 			((rstrm->in_finger + len) <= rstrm->in_boundry)) {
398 			buf = (int32_t *)(void *)rstrm->in_finger;
399 			rstrm->fbtbc -= len;
400 			rstrm->in_finger += len;
401 		}
402 		break;
403 	case XDR_FREE:
404 		break;
405 	}
406 	return (buf);
407 }
408 
409 static void
410 xdrrec_destroy(XDR *xdrs)
411 {
412 	RECSTREAM *rstrm = (RECSTREAM *)xdrs->x_private;
413 
414 	mem_free(rstrm->out_base, rstrm->sendsize);
415 	mem_free(rstrm->in_base, rstrm->recvsize);
416 	mem_free(rstrm, sizeof(RECSTREAM));
417 }
418 
419 
420 /*
421  * Exported routines to manage xdr records
422  */
423 
424 /*
425  * Before reading (deserializing from the stream, one should always call
426  * this procedure to guarantee proper record alignment.
427  */
428 bool_t
429 xdrrec_skiprecord(XDR *xdrs)
430 {
431 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
432 	enum xprt_stat xstat;
433 
434 	if (rstrm->nonblock) {
435 		if (__xdrrec_getrec(xdrs, &xstat, FALSE)) {
436 			rstrm->fbtbc = 0;
437 			return TRUE;
438 		}
439 		if (rstrm->in_finger == rstrm->in_boundry &&
440 		    xstat == XPRT_MOREREQS) {
441 			rstrm->fbtbc = 0;
442 			return TRUE;
443 		}
444 		return FALSE;
445 	}
446 
447 	while (rstrm->fbtbc > 0 || (! rstrm->last_frag)) {
448 		if (! skip_input_bytes(rstrm, rstrm->fbtbc))
449 			return (FALSE);
450 		rstrm->fbtbc = 0;
451 		if ((! rstrm->last_frag) && (! set_input_fragment(rstrm)))
452 			return (FALSE);
453 	}
454 	rstrm->last_frag = FALSE;
455 	return (TRUE);
456 }
457 
458 /*
459  * Look ahead function.
460  * Returns TRUE iff there is no more input in the buffer
461  * after consuming the rest of the current record.
462  */
463 bool_t
464 xdrrec_eof(XDR *xdrs)
465 {
466 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
467 
468 	while (rstrm->fbtbc > 0 || (! rstrm->last_frag)) {
469 		if (! skip_input_bytes(rstrm, rstrm->fbtbc))
470 			return (TRUE);
471 		rstrm->fbtbc = 0;
472 		if ((! rstrm->last_frag) && (! set_input_fragment(rstrm)))
473 			return (TRUE);
474 	}
475 	if (rstrm->in_finger == rstrm->in_boundry)
476 		return (TRUE);
477 	return (FALSE);
478 }
479 
480 /*
481  * The client must tell the package when an end-of-record has occurred.
482  * The second paraemters tells whether the record should be flushed to the
483  * (output) tcp stream.  (This let's the package support batched or
484  * pipelined procedure calls.)  TRUE => immmediate flush to tcp connection.
485  */
486 bool_t
487 xdrrec_endofrecord(XDR *xdrs, bool_t sendnow)
488 {
489 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
490 	u_long len;  /* fragment length */
491 
492 	if (sendnow || rstrm->frag_sent ||
493 		((u_long)rstrm->out_finger + sizeof(uint32_t) >=
494 		(u_long)rstrm->out_boundry)) {
495 		rstrm->frag_sent = FALSE;
496 		return (flush_out(rstrm, TRUE));
497 	}
498 	len = (u_long)(rstrm->out_finger) - (u_long)(rstrm->frag_header) -
499 	   sizeof(uint32_t);
500 	*(rstrm->frag_header) = htonl((uint32_t)len | LAST_FRAG);
501 	rstrm->frag_header = (uint32_t *)(void *)rstrm->out_finger;
502 	rstrm->out_finger += sizeof(uint32_t);
503 	return (TRUE);
504 }
505 
506 /*
507  * Fill the stream buffer with a record for a non-blocking connection.
508  * Return true if a record is available in the buffer, false if not.
509  */
510 bool_t
511 __xdrrec_getrec(XDR *xdrs, enum xprt_stat *statp, bool_t expectdata)
512 {
513 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
514 	ssize_t n;
515 	int fraglen;
516 
517 	if (!rstrm->in_haveheader) {
518 		n = rstrm->readit(rstrm->tcp_handle, rstrm->in_hdrp,
519 		    (int)sizeof (rstrm->in_header) - rstrm->in_hdrlen);
520 		if (n == 0) {
521 			*statp = expectdata ? XPRT_DIED : XPRT_IDLE;
522 			return FALSE;
523 		}
524 		if (n < 0) {
525 			*statp = XPRT_DIED;
526 			return FALSE;
527 		}
528 		rstrm->in_hdrp += n;
529 		rstrm->in_hdrlen += n;
530 		if (rstrm->in_hdrlen < sizeof (rstrm->in_header)) {
531 			*statp = XPRT_MOREREQS;
532 			return FALSE;
533 		}
534 		rstrm->in_header = ntohl(rstrm->in_header);
535 		fraglen = (int)(rstrm->in_header & ~LAST_FRAG);
536 		if (fraglen == 0 || fraglen > rstrm->in_maxrec ||
537 		    (rstrm->in_reclen + fraglen) > rstrm->in_maxrec) {
538 			*statp = XPRT_DIED;
539 			return FALSE;
540 		}
541 		rstrm->in_reclen += fraglen;
542 		if (rstrm->in_reclen > rstrm->recvsize)
543 			realloc_stream(rstrm, rstrm->in_reclen);
544 		if (rstrm->in_header & LAST_FRAG) {
545 			rstrm->in_header &= ~LAST_FRAG;
546 			rstrm->last_frag = TRUE;
547 		}
548 		/*
549 		 * We can only reasonably expect to read once from a
550 		 * non-blocking stream. Reading the fragment header
551 		 * may have drained the stream.
552 		 */
553 		expectdata = FALSE;
554 	}
555 
556 	n =  rstrm->readit(rstrm->tcp_handle,
557 	    rstrm->in_base + rstrm->in_received,
558 	    (rstrm->in_reclen - rstrm->in_received));
559 
560 	if (n < 0) {
561 		*statp = XPRT_DIED;
562 		return FALSE;
563 	}
564 
565 	if (n == 0) {
566 		*statp = expectdata ? XPRT_DIED : XPRT_IDLE;
567 		return FALSE;
568 	}
569 
570 	rstrm->in_received += n;
571 
572 	if (rstrm->in_received == rstrm->in_reclen) {
573 		rstrm->in_haveheader = FALSE;
574 		rstrm->in_hdrp = (char *)(void *)&rstrm->in_header;
575 		rstrm->in_hdrlen = 0;
576 		if (rstrm->last_frag) {
577 			rstrm->fbtbc = rstrm->in_reclen;
578 			rstrm->in_boundry = rstrm->in_base + rstrm->in_reclen;
579 			rstrm->in_finger = rstrm->in_base;
580 			rstrm->in_reclen = rstrm->in_received = 0;
581 			*statp = XPRT_MOREREQS;
582 			return TRUE;
583 		}
584 	}
585 
586 	*statp = XPRT_MOREREQS;
587 	return FALSE;
588 }
589 
590 bool_t
591 __xdrrec_setnonblock(XDR *xdrs, int maxrec)
592 {
593 	RECSTREAM *rstrm = (RECSTREAM *)(xdrs->x_private);
594 
595 	rstrm->nonblock = TRUE;
596 	if (maxrec == 0)
597 		maxrec = rstrm->recvsize;
598 	rstrm->in_maxrec = maxrec;
599 	return TRUE;
600 }
601 
602 /*
603  * Internal useful routines
604  */
605 static bool_t
606 flush_out(RECSTREAM *rstrm, bool_t eor)
607 {
608 	uint32_t eormask = (eor == TRUE) ? LAST_FRAG : 0;
609 	uint32_t len = (uint32_t)((u_long)(rstrm->out_finger) -
610 		(u_long)(rstrm->frag_header) - sizeof(uint32_t));
611 
612 	*(rstrm->frag_header) = htonl(len | eormask);
613 	len = (uint32_t)((u_long)(rstrm->out_finger) -
614 	    (u_long)(rstrm->out_base));
615 	if ((*(rstrm->writeit))(rstrm->tcp_handle, rstrm->out_base, (int)len)
616 		!= (int)len)
617 		return (FALSE);
618 	rstrm->frag_header = (uint32_t *)(void *)rstrm->out_base;
619 	rstrm->out_finger = (char *)rstrm->out_base + sizeof(uint32_t);
620 	return (TRUE);
621 }
622 
623 static bool_t  /* knows nothing about records!  Only about input buffers */
624 fill_input_buf(RECSTREAM *rstrm)
625 {
626 	char *where;
627 	uint32_t i;
628 	int len;
629 
630 	if (rstrm->nonblock)
631 		return FALSE;
632 
633 	where = rstrm->in_base;
634 	i = (uint32_t)((u_long)rstrm->in_boundry % BYTES_PER_XDR_UNIT);
635 	where += i;
636 	len = (uint32_t)(rstrm->in_size - i);
637 	if ((len = (*(rstrm->readit))(rstrm->tcp_handle, where, len)) == -1)
638 		return (FALSE);
639 	rstrm->in_finger = where;
640 	where += len;
641 	rstrm->in_boundry = where;
642 	return (TRUE);
643 }
644 
645 static bool_t  /* knows nothing about records!  Only about input buffers */
646 get_input_bytes(RECSTREAM *rstrm, char *addr, int len)
647 {
648 	size_t current;
649 
650 	if (rstrm->nonblock) {
651 		if (len > (int)(rstrm->in_boundry - rstrm->in_finger))
652 			return FALSE;
653 		memcpy(addr, rstrm->in_finger, (size_t)len);
654 		rstrm->in_finger += len;
655 		return TRUE;
656 	}
657 
658 	while (len > 0) {
659 		current = (size_t)((long)rstrm->in_boundry -
660 		    (long)rstrm->in_finger);
661 		if (current == 0) {
662 			if (! fill_input_buf(rstrm))
663 				return (FALSE);
664 			continue;
665 		}
666 		current = (len < current) ? len : current;
667 		memmove(addr, rstrm->in_finger, current);
668 		rstrm->in_finger += current;
669 		addr += current;
670 		len -= current;
671 	}
672 	return (TRUE);
673 }
674 
675 static bool_t  /* next two bytes of the input stream are treated as a header */
676 set_input_fragment(RECSTREAM *rstrm)
677 {
678 	uint32_t header;
679 
680 	if (rstrm->nonblock)
681 		return FALSE;
682 	if (! get_input_bytes(rstrm, (char *)(void *)&header, sizeof(header)))
683 		return (FALSE);
684 	header = ntohl(header);
685 	rstrm->last_frag = ((header & LAST_FRAG) == 0) ? FALSE : TRUE;
686 	/*
687 	 * Sanity check. Try not to accept wildly incorrect
688 	 * record sizes. Unfortunately, the only record size
689 	 * we can positively identify as being 'wildly incorrect'
690 	 * is zero. Ridiculously large record sizes may look wrong,
691 	 * but we don't have any way to be certain that they aren't
692 	 * what the client actually intended to send us.
693 	 */
694 	if (header == 0)
695 		return(FALSE);
696 	rstrm->fbtbc = header & (~LAST_FRAG);
697 	return (TRUE);
698 }
699 
700 static bool_t  /* consumes input bytes; knows nothing about records! */
701 skip_input_bytes(RECSTREAM *rstrm, long cnt)
702 {
703 	uint32_t current;
704 
705 	while (cnt > 0) {
706 		current = (size_t)((long)rstrm->in_boundry -
707 		    (long)rstrm->in_finger);
708 		if (current == 0) {
709 			if (! fill_input_buf(rstrm))
710 				return (FALSE);
711 			continue;
712 		}
713 		current = (uint32_t)((cnt < current) ? cnt : current);
714 		rstrm->in_finger += current;
715 		cnt -= current;
716 	}
717 	return (TRUE);
718 }
719 
720 static u_int
721 fix_buf_size(u_int s)
722 {
723 
724 	if (s < 100)
725 		s = 4000;
726 	return (RNDUP(s));
727 }
728 
729 /*
730  * Reallocate the input buffer for a non-block stream.
731  */
732 static bool_t
733 realloc_stream(RECSTREAM *rstrm, int size)
734 {
735 	ptrdiff_t diff;
736 	char *buf;
737 
738 	if (size > rstrm->recvsize) {
739 		buf = realloc(rstrm->in_base, (size_t)size);
740 		if (buf == NULL)
741 			return FALSE;
742 		diff = buf - rstrm->in_base;
743 		rstrm->in_finger += diff;
744 		rstrm->in_base = buf;
745 		rstrm->in_boundry = buf + size;
746 		rstrm->recvsize = size;
747 		rstrm->in_size = size;
748 	}
749 
750 	return TRUE;
751 }
752