1/* crypto/bio/bss_bio.c  -*- Mode: C; c-file-style: "eay" -*- */
2/* ====================================================================
3 * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 *
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 *
12 * 2. Redistributions in binary form must reproduce the above copyright
13 *    notice, this list of conditions and the following disclaimer in
14 *    the documentation and/or other materials provided with the
15 *    distribution.
16 *
17 * 3. All advertising materials mentioning features or use of this
18 *    software must display the following acknowledgment:
19 *    "This product includes software developed by the OpenSSL Project
20 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
21 *
22 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
23 *    endorse or promote products derived from this software without
24 *    prior written permission. For written permission, please contact
25 *    openssl-core@openssl.org.
26 *
27 * 5. Products derived from this software may not be called "OpenSSL"
28 *    nor may "OpenSSL" appear in their names without prior written
29 *    permission of the OpenSSL Project.
30 *
31 * 6. Redistributions of any form whatsoever must retain the following
32 *    acknowledgment:
33 *    "This product includes software developed by the OpenSSL Project
34 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
35 *
36 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
37 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
38 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
39 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
40 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
41 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
42 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
43 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
44 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
45 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
46 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
47 * OF THE POSSIBILITY OF SUCH DAMAGE.
48 * ====================================================================
49 *
50 * This product includes cryptographic software written by Eric Young
51 * (eay@cryptsoft.com).  This product includes software written by Tim
52 * Hudson (tjh@cryptsoft.com).
53 *
54 */
55
56/* Special method for a BIO where the other endpoint is also a BIO
57 * of this kind, handled by the same thread (i.e. the "peer" is actually
58 * ourselves, wearing a different hat).
59 * Such "BIO pairs" are mainly for using the SSL library with I/O interfaces
60 * for which no specific BIO method is available.
61 * See ssl/ssltest.c for some hints on how this can be used. */
62
63
64/* BIO_DEBUG implies BIO_PAIR_DEBUG */
65#ifdef BIO_DEBUG
66# ifndef BIO_PAIR_DEBUG
67#  define BIO_PAIR_DEBUG
68# endif
69#endif
70
71/* disable assert() unless BIO_PAIR_DEBUG has been defined */
72#ifndef BIO_PAIR_DEBUG
73# ifndef NDEBUG
74#  define NDEBUG
75# endif
76#endif
77
78#include <assert.h>
79#include <limits.h>
80#include <stdlib.h>
81#include <string.h>
82
83#include <openssl/bio.h>
84#include <openssl/err.h>
85#include <openssl/crypto.h>
86
87#include "e_os.h"
88
89/* VxWorks defines SSIZE_MAX with an empty value causing compile errors */
90#if defined(OPENSSL_SYS_VXWORKS)
91# undef SSIZE_MAX
92#endif
93#ifndef SSIZE_MAX
94# define SSIZE_MAX INT_MAX
95#endif
96
97static int bio_new(BIO *bio);
98static int bio_free(BIO *bio);
99static int bio_read(BIO *bio, char *buf, int size);
100static int bio_write(BIO *bio, const char *buf, int num);
101static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr);
102static int bio_puts(BIO *bio, const char *str);
103
104static int bio_make_pair(BIO *bio1, BIO *bio2);
105static void bio_destroy_pair(BIO *bio);
106
107static BIO_METHOD methods_biop =
108{
109	BIO_TYPE_BIO,
110	"BIO pair",
111	bio_write,
112	bio_read,
113	bio_puts,
114	NULL /* no bio_gets */,
115	bio_ctrl,
116	bio_new,
117	bio_free,
118	NULL /* no bio_callback_ctrl */
119};
120
121BIO_METHOD *BIO_s_bio(void)
122	{
123	return &methods_biop;
124	}
125
126struct bio_bio_st
127{
128	BIO *peer;     /* NULL if buf == NULL.
129	                * If peer != NULL, then peer->ptr is also a bio_bio_st,
130	                * and its "peer" member points back to us.
131	                * peer != NULL iff init != 0 in the BIO. */
132
133	/* This is for what we write (i.e. reading uses peer's struct): */
134	int closed;     /* valid iff peer != NULL */
135	size_t len;     /* valid iff buf != NULL; 0 if peer == NULL */
136	size_t offset;  /* valid iff buf != NULL; 0 if len == 0 */
137	size_t size;
138	char *buf;      /* "size" elements (if != NULL) */
139
140	size_t request; /* valid iff peer != NULL; 0 if len != 0,
141	                 * otherwise set by peer to number of bytes
142	                 * it (unsuccessfully) tried to read,
143	                 * never more than buffer space (size-len) warrants. */
144};
145
146static int bio_new(BIO *bio)
147	{
148	struct bio_bio_st *b;
149
150	b = OPENSSL_malloc(sizeof *b);
151	if (b == NULL)
152		return 0;
153
154	b->peer = NULL;
155	b->size = 17*1024; /* enough for one TLS record (just a default) */
156	b->buf = NULL;
157
158	bio->ptr = b;
159	return 1;
160	}
161
162
163static int bio_free(BIO *bio)
164	{
165	struct bio_bio_st *b;
166
167	if (bio == NULL)
168		return 0;
169	b = bio->ptr;
170
171	assert(b != NULL);
172
173	if (b->peer)
174		bio_destroy_pair(bio);
175
176	if (b->buf != NULL)
177		{
178		OPENSSL_free(b->buf);
179		}
180
181	OPENSSL_free(b);
182
183	return 1;
184	}
185
186
187
188static int bio_read(BIO *bio, char *buf, int size_)
189	{
190	size_t size = size_;
191	size_t rest;
192	struct bio_bio_st *b, *peer_b;
193
194	BIO_clear_retry_flags(bio);
195
196	if (!bio->init)
197		return 0;
198
199	b = bio->ptr;
200	assert(b != NULL);
201	assert(b->peer != NULL);
202	peer_b = b->peer->ptr;
203	assert(peer_b != NULL);
204	assert(peer_b->buf != NULL);
205
206	peer_b->request = 0; /* will be set in "retry_read" situation */
207
208	if (buf == NULL || size == 0)
209		return 0;
210
211	if (peer_b->len == 0)
212		{
213		if (peer_b->closed)
214			return 0; /* writer has closed, and no data is left */
215		else
216			{
217			BIO_set_retry_read(bio); /* buffer is empty */
218			if (size <= peer_b->size)
219				peer_b->request = size;
220			else
221				/* don't ask for more than the peer can
222				 * deliver in one write */
223				peer_b->request = peer_b->size;
224			return -1;
225			}
226		}
227
228	/* we can read */
229	if (peer_b->len < size)
230		size = peer_b->len;
231
232	/* now read "size" bytes */
233
234	rest = size;
235
236	assert(rest > 0);
237	do /* one or two iterations */
238		{
239		size_t chunk;
240
241		assert(rest <= peer_b->len);
242		if (peer_b->offset + rest <= peer_b->size)
243			chunk = rest;
244		else
245			/* wrap around ring buffer */
246			chunk = peer_b->size - peer_b->offset;
247		assert(peer_b->offset + chunk <= peer_b->size);
248
249		memcpy(buf, peer_b->buf + peer_b->offset, chunk);
250
251		peer_b->len -= chunk;
252		if (peer_b->len)
253			{
254			peer_b->offset += chunk;
255			assert(peer_b->offset <= peer_b->size);
256			if (peer_b->offset == peer_b->size)
257				peer_b->offset = 0;
258			buf += chunk;
259			}
260		else
261			{
262			/* buffer now empty, no need to advance "buf" */
263			assert(chunk == rest);
264			peer_b->offset = 0;
265			}
266		rest -= chunk;
267		}
268	while (rest);
269
270	return size;
271	}
272
273/* non-copying interface: provide pointer to available data in buffer
274 *    bio_nread0:  return number of available bytes
275 *    bio_nread:   also advance index
276 * (example usage:  bio_nread0(), read from buffer, bio_nread()
277 *  or just         bio_nread(), read from buffer)
278 */
279/* WARNING: The non-copying interface is largely untested as of yet
280 * and may contain bugs. */
281static ssize_t bio_nread0(BIO *bio, char **buf)
282	{
283	struct bio_bio_st *b, *peer_b;
284	ssize_t num;
285
286	BIO_clear_retry_flags(bio);
287
288	if (!bio->init)
289		return 0;
290
291	b = bio->ptr;
292	assert(b != NULL);
293	assert(b->peer != NULL);
294	peer_b = b->peer->ptr;
295	assert(peer_b != NULL);
296	assert(peer_b->buf != NULL);
297
298	peer_b->request = 0;
299
300	if (peer_b->len == 0)
301		{
302		char dummy;
303
304		/* avoid code duplication -- nothing available for reading */
305		return bio_read(bio, &dummy, 1); /* returns 0 or -1 */
306		}
307
308	num = peer_b->len;
309	if (peer_b->size < peer_b->offset + num)
310		/* no ring buffer wrap-around for non-copying interface */
311		num = peer_b->size - peer_b->offset;
312	assert(num > 0);
313
314	if (buf != NULL)
315		*buf = peer_b->buf + peer_b->offset;
316	return num;
317	}
318
319static ssize_t bio_nread(BIO *bio, char **buf, size_t num_)
320	{
321	struct bio_bio_st *b, *peer_b;
322	ssize_t num, available;
323
324	if (num_ > SSIZE_MAX)
325		num = SSIZE_MAX;
326	else
327		num = (ssize_t)num_;
328
329	available = bio_nread0(bio, buf);
330	if (num > available)
331		num = available;
332	if (num <= 0)
333		return num;
334
335	b = bio->ptr;
336	peer_b = b->peer->ptr;
337
338	peer_b->len -= num;
339	if (peer_b->len)
340		{
341		peer_b->offset += num;
342		assert(peer_b->offset <= peer_b->size);
343		if (peer_b->offset == peer_b->size)
344			peer_b->offset = 0;
345		}
346	else
347		peer_b->offset = 0;
348
349	return num;
350	}
351
352
353static int bio_write(BIO *bio, const char *buf, int num_)
354	{
355	size_t num = num_;
356	size_t rest;
357	struct bio_bio_st *b;
358
359	BIO_clear_retry_flags(bio);
360
361	if (!bio->init || buf == NULL || num == 0)
362		return 0;
363
364	b = bio->ptr;
365	assert(b != NULL);
366	assert(b->peer != NULL);
367	assert(b->buf != NULL);
368
369	b->request = 0;
370	if (b->closed)
371		{
372		/* we already closed */
373		BIOerr(BIO_F_BIO_WRITE, BIO_R_BROKEN_PIPE);
374		return -1;
375		}
376
377	assert(b->len <= b->size);
378
379	if (b->len == b->size)
380		{
381		BIO_set_retry_write(bio); /* buffer is full */
382		return -1;
383		}
384
385	/* we can write */
386	if (num > b->size - b->len)
387		num = b->size - b->len;
388
389	/* now write "num" bytes */
390
391	rest = num;
392
393	assert(rest > 0);
394	do /* one or two iterations */
395		{
396		size_t write_offset;
397		size_t chunk;
398
399		assert(b->len + rest <= b->size);
400
401		write_offset = b->offset + b->len;
402		if (write_offset >= b->size)
403			write_offset -= b->size;
404		/* b->buf[write_offset] is the first byte we can write to. */
405
406		if (write_offset + rest <= b->size)
407			chunk = rest;
408		else
409			/* wrap around ring buffer */
410			chunk = b->size - write_offset;
411
412		memcpy(b->buf + write_offset, buf, chunk);
413
414		b->len += chunk;
415
416		assert(b->len <= b->size);
417
418		rest -= chunk;
419		buf += chunk;
420		}
421	while (rest);
422
423	return num;
424	}
425
426/* non-copying interface: provide pointer to region to write to
427 *   bio_nwrite0:  check how much space is available
428 *   bio_nwrite:   also increase length
429 * (example usage:  bio_nwrite0(), write to buffer, bio_nwrite()
430 *  or just         bio_nwrite(), write to buffer)
431 */
432static ssize_t bio_nwrite0(BIO *bio, char **buf)
433	{
434	struct bio_bio_st *b;
435	size_t num;
436	size_t write_offset;
437
438	BIO_clear_retry_flags(bio);
439
440	if (!bio->init)
441		return 0;
442
443	b = bio->ptr;
444	assert(b != NULL);
445	assert(b->peer != NULL);
446	assert(b->buf != NULL);
447
448	b->request = 0;
449	if (b->closed)
450		{
451		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_BROKEN_PIPE);
452		return -1;
453		}
454
455	assert(b->len <= b->size);
456
457	if (b->len == b->size)
458		{
459		BIO_set_retry_write(bio);
460		return -1;
461		}
462
463	num = b->size - b->len;
464	write_offset = b->offset + b->len;
465	if (write_offset >= b->size)
466		write_offset -= b->size;
467	if (write_offset + num > b->size)
468		/* no ring buffer wrap-around for non-copying interface
469		 * (to fulfil the promise by BIO_ctrl_get_write_guarantee,
470		 * BIO_nwrite may have to be called twice) */
471		num = b->size - write_offset;
472
473	if (buf != NULL)
474		*buf = b->buf + write_offset;
475	assert(write_offset + num <= b->size);
476
477	return num;
478	}
479
480static ssize_t bio_nwrite(BIO *bio, char **buf, size_t num_)
481	{
482	struct bio_bio_st *b;
483	ssize_t num, space;
484
485	if (num_ > SSIZE_MAX)
486		num = SSIZE_MAX;
487	else
488		num = (ssize_t)num_;
489
490	space = bio_nwrite0(bio, buf);
491	if (num > space)
492		num = space;
493	if (num <= 0)
494		return num;
495	b = bio->ptr;
496	assert(b != NULL);
497	b->len += num;
498	assert(b->len <= b->size);
499
500	return num;
501	}
502
503
504static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr)
505	{
506	long ret;
507	struct bio_bio_st *b = bio->ptr;
508
509	assert(b != NULL);
510
511	switch (cmd)
512		{
513	/* specific CTRL codes */
514
515	case BIO_C_SET_WRITE_BUF_SIZE:
516		if (b->peer)
517			{
518			BIOerr(BIO_F_BIO_CTRL, BIO_R_IN_USE);
519			ret = 0;
520			}
521		else if (num == 0)
522			{
523			BIOerr(BIO_F_BIO_CTRL, BIO_R_INVALID_ARGUMENT);
524			ret = 0;
525			}
526		else
527			{
528			size_t new_size = num;
529
530			if (b->size != new_size)
531				{
532				if (b->buf)
533					{
534					OPENSSL_free(b->buf);
535					b->buf = NULL;
536					}
537				b->size = new_size;
538				}
539			ret = 1;
540			}
541		break;
542
543	case BIO_C_GET_WRITE_BUF_SIZE:
544		ret = (long) b->size;
545		break;
546
547	case BIO_C_MAKE_BIO_PAIR:
548		{
549		BIO *other_bio = ptr;
550
551		if (bio_make_pair(bio, other_bio))
552			ret = 1;
553		else
554			ret = 0;
555		}
556		break;
557
558	case BIO_C_DESTROY_BIO_PAIR:
559		/* Affects both BIOs in the pair -- call just once!
560		 * Or let BIO_free(bio1); BIO_free(bio2); do the job. */
561		bio_destroy_pair(bio);
562		ret = 1;
563		break;
564
565	case BIO_C_GET_WRITE_GUARANTEE:
566		/* How many bytes can the caller feed to the next write
567		 * without having to keep any? */
568		if (b->peer == NULL || b->closed)
569			ret = 0;
570		else
571			ret = (long) b->size - b->len;
572		break;
573
574	case BIO_C_GET_READ_REQUEST:
575		/* If the peer unsuccessfully tried to read, how many bytes
576		 * were requested?  (As with BIO_CTRL_PENDING, that number
577		 * can usually be treated as boolean.) */
578		ret = (long) b->request;
579		break;
580
581	case BIO_C_RESET_READ_REQUEST:
582		/* Reset request.  (Can be useful after read attempts
583		 * at the other side that are meant to be non-blocking,
584		 * e.g. when probing SSL_read to see if any data is
585		 * available.) */
586		b->request = 0;
587		ret = 1;
588		break;
589
590	case BIO_C_SHUTDOWN_WR:
591		/* similar to shutdown(..., SHUT_WR) */
592		b->closed = 1;
593		ret = 1;
594		break;
595
596	case BIO_C_NREAD0:
597		/* prepare for non-copying read */
598		ret = (long) bio_nread0(bio, ptr);
599		break;
600
601	case BIO_C_NREAD:
602		/* non-copying read */
603		ret = (long) bio_nread(bio, ptr, (size_t) num);
604		break;
605
606	case BIO_C_NWRITE0:
607		/* prepare for non-copying write */
608		ret = (long) bio_nwrite0(bio, ptr);
609		break;
610
611	case BIO_C_NWRITE:
612		/* non-copying write */
613		ret = (long) bio_nwrite(bio, ptr, (size_t) num);
614		break;
615
616
617	/* standard CTRL codes follow */
618
619	case BIO_CTRL_RESET:
620		if (b->buf != NULL)
621			{
622			b->len = 0;
623			b->offset = 0;
624			}
625		ret = 0;
626		break;
627
628	case BIO_CTRL_GET_CLOSE:
629		ret = bio->shutdown;
630		break;
631
632	case BIO_CTRL_SET_CLOSE:
633		bio->shutdown = (int) num;
634		ret = 1;
635		break;
636
637	case BIO_CTRL_PENDING:
638		if (b->peer != NULL)
639			{
640			struct bio_bio_st *peer_b = b->peer->ptr;
641
642			ret = (long) peer_b->len;
643			}
644		else
645			ret = 0;
646		break;
647
648	case BIO_CTRL_WPENDING:
649		if (b->buf != NULL)
650			ret = (long) b->len;
651		else
652			ret = 0;
653		break;
654
655	case BIO_CTRL_DUP:
656		/* See BIO_dup_chain for circumstances we have to expect. */
657		{
658		BIO *other_bio = ptr;
659		struct bio_bio_st *other_b;
660
661		assert(other_bio != NULL);
662		other_b = other_bio->ptr;
663		assert(other_b != NULL);
664
665		assert(other_b->buf == NULL); /* other_bio is always fresh */
666
667		other_b->size = b->size;
668		}
669
670		ret = 1;
671		break;
672
673	case BIO_CTRL_FLUSH:
674		ret = 1;
675		break;
676
677	case BIO_CTRL_EOF:
678		{
679		BIO *other_bio = ptr;
680
681		if (other_bio)
682			{
683			struct bio_bio_st *other_b = other_bio->ptr;
684
685			assert(other_b != NULL);
686			ret = other_b->len == 0 && other_b->closed;
687			}
688		else
689			ret = 1;
690		}
691		break;
692
693	default:
694		ret = 0;
695		}
696	return ret;
697	}
698
699static int bio_puts(BIO *bio, const char *str)
700	{
701	return bio_write(bio, str, strlen(str));
702	}
703
704
705static int bio_make_pair(BIO *bio1, BIO *bio2)
706	{
707	struct bio_bio_st *b1, *b2;
708
709	assert(bio1 != NULL);
710	assert(bio2 != NULL);
711
712	b1 = bio1->ptr;
713	b2 = bio2->ptr;
714
715	if (b1->peer != NULL || b2->peer != NULL)
716		{
717		BIOerr(BIO_F_BIO_MAKE_PAIR, BIO_R_IN_USE);
718		return 0;
719		}
720
721	if (b1->buf == NULL)
722		{
723		b1->buf = OPENSSL_malloc(b1->size);
724		if (b1->buf == NULL)
725			{
726			BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);
727			return 0;
728			}
729		b1->len = 0;
730		b1->offset = 0;
731		}
732
733	if (b2->buf == NULL)
734		{
735		b2->buf = OPENSSL_malloc(b2->size);
736		if (b2->buf == NULL)
737			{
738			BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);
739			return 0;
740			}
741		b2->len = 0;
742		b2->offset = 0;
743		}
744
745	b1->peer = bio2;
746	b1->closed = 0;
747	b1->request = 0;
748	b2->peer = bio1;
749	b2->closed = 0;
750	b2->request = 0;
751
752	bio1->init = 1;
753	bio2->init = 1;
754
755	return 1;
756	}
757
758static void bio_destroy_pair(BIO *bio)
759	{
760	struct bio_bio_st *b = bio->ptr;
761
762	if (b != NULL)
763		{
764		BIO *peer_bio = b->peer;
765
766		if (peer_bio != NULL)
767			{
768			struct bio_bio_st *peer_b = peer_bio->ptr;
769
770			assert(peer_b != NULL);
771			assert(peer_b->peer == bio);
772
773			peer_b->peer = NULL;
774			peer_bio->init = 0;
775			assert(peer_b->buf != NULL);
776			peer_b->len = 0;
777			peer_b->offset = 0;
778
779			b->peer = NULL;
780			bio->init = 0;
781			assert(b->buf != NULL);
782			b->len = 0;
783			b->offset = 0;
784			}
785		}
786	}
787
788
789/* Exported convenience functions */
790int BIO_new_bio_pair(BIO **bio1_p, size_t writebuf1,
791	BIO **bio2_p, size_t writebuf2)
792	 {
793	 BIO *bio1 = NULL, *bio2 = NULL;
794	 long r;
795	 int ret = 0;
796
797	 bio1 = BIO_new(BIO_s_bio());
798	 if (bio1 == NULL)
799		 goto err;
800	 bio2 = BIO_new(BIO_s_bio());
801	 if (bio2 == NULL)
802		 goto err;
803
804	 if (writebuf1)
805		 {
806		 r = BIO_set_write_buf_size(bio1, writebuf1);
807		 if (!r)
808			 goto err;
809		 }
810	 if (writebuf2)
811		 {
812		 r = BIO_set_write_buf_size(bio2, writebuf2);
813		 if (!r)
814			 goto err;
815		 }
816
817	 r = BIO_make_bio_pair(bio1, bio2);
818	 if (!r)
819		 goto err;
820	 ret = 1;
821
822 err:
823	 if (ret == 0)
824		 {
825		 if (bio1)
826			 {
827			 BIO_free(bio1);
828			 bio1 = NULL;
829			 }
830		 if (bio2)
831			 {
832			 BIO_free(bio2);
833			 bio2 = NULL;
834			 }
835		 }
836
837	 *bio1_p = bio1;
838	 *bio2_p = bio2;
839	 return ret;
840	 }
841
842size_t BIO_ctrl_get_write_guarantee(BIO *bio)
843	{
844	return BIO_ctrl(bio, BIO_C_GET_WRITE_GUARANTEE, 0, NULL);
845	}
846
847size_t BIO_ctrl_get_read_request(BIO *bio)
848	{
849	return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);
850	}
851
852int BIO_ctrl_reset_read_request(BIO *bio)
853	{
854	return (BIO_ctrl(bio, BIO_C_RESET_READ_REQUEST, 0, NULL) != 0);
855	}
856
857
858/* BIO_nread0/nread/nwrite0/nwrite are available only for BIO pairs for now
859 * (conceivably some other BIOs could allow non-copying reads and writes too.)
860 */
861int BIO_nread0(BIO *bio, char **buf)
862	{
863	long ret;
864
865	if (!bio->init)
866		{
867		BIOerr(BIO_F_BIO_NREAD0, BIO_R_UNINITIALIZED);
868		return -2;
869		}
870
871	ret = BIO_ctrl(bio, BIO_C_NREAD0, 0, buf);
872	if (ret > INT_MAX)
873		return INT_MAX;
874	else
875		return (int) ret;
876	}
877
878int BIO_nread(BIO *bio, char **buf, int num)
879	{
880	int ret;
881
882	if (!bio->init)
883		{
884		BIOerr(BIO_F_BIO_NREAD, BIO_R_UNINITIALIZED);
885		return -2;
886		}
887
888	ret = (int) BIO_ctrl(bio, BIO_C_NREAD, num, buf);
889	if (ret > 0)
890		bio->num_read += ret;
891	return ret;
892	}
893
894int BIO_nwrite0(BIO *bio, char **buf)
895	{
896	long ret;
897
898	if (!bio->init)
899		{
900		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_UNINITIALIZED);
901		return -2;
902		}
903
904	ret = BIO_ctrl(bio, BIO_C_NWRITE0, 0, buf);
905	if (ret > INT_MAX)
906		return INT_MAX;
907	else
908		return (int) ret;
909	}
910
911int BIO_nwrite(BIO *bio, char **buf, int num)
912	{
913	int ret;
914
915	if (!bio->init)
916		{
917		BIOerr(BIO_F_BIO_NWRITE, BIO_R_UNINITIALIZED);
918		return -2;
919		}
920
921	ret = BIO_ctrl(bio, BIO_C_NWRITE, num, buf);
922	if (ret > 0)
923		bio->num_write += ret;
924	return ret;
925	}
926