bss_bio.c revision 392aa7cc7d2b122614c5393c3e357da07fd07af3 
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/* BIO_DEBUG implies BIO_PAIR_DEBUG */
64#ifdef BIO_DEBUG
65# ifndef BIO_PAIR_DEBUG
66#  define BIO_PAIR_DEBUG
67# endif
68#endif
69
70/* disable assert() unless BIO_PAIR_DEBUG has been defined */
71#ifndef BIO_PAIR_DEBUG
72# ifndef NDEBUG
73#  define NDEBUG
74# endif
75#endif
76
77#include <assert.h>
78#include <limits.h>
79#include <stdlib.h>
80#include <string.h>
81
82#include <openssl/bio.h>
83#include <openssl/err.h>
84#include <openssl/crypto.h>
85
86#include "e_os.h"
87
88/* VxWorks defines SSIZE_MAX with an empty value causing compile errors */
89#if defined(OPENSSL_SYS_VXWORKS)
90# undef SSIZE_MAX
91#endif
92#ifndef SSIZE_MAX
93# define SSIZE_MAX INT_MAX
94#endif
95
96static int bio_new(BIO *bio);
97static int bio_free(BIO *bio);
98static int bio_read(BIO *bio, char *buf, int size);
99static int bio_write(BIO *bio, const char *buf, int num);
100static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr);
101static int bio_puts(BIO *bio, const char *str);
102
103static int bio_make_pair(BIO *bio1, BIO *bio2);
104static void bio_destroy_pair(BIO *bio);
105
106static BIO_METHOD methods_biop =
107{
108	BIO_TYPE_BIO,
109	"BIO pair",
110	bio_write,
111	bio_read,
112	bio_puts,
113	NULL /* no bio_gets */,
114	bio_ctrl,
115	bio_new,
116	bio_free,
117	NULL /* no bio_callback_ctrl */
118};
119
120BIO_METHOD *BIO_s_bio(void)
121	{
122	return &methods_biop;
123	}
124
125struct bio_bio_st
126{
127	BIO *peer;     /* NULL if buf == NULL.
128	                * If peer != NULL, then peer->ptr is also a bio_bio_st,
129	                * and its "peer" member points back to us.
130	                * peer != NULL iff init != 0 in the BIO. */
131
132	/* This is for what we write (i.e. reading uses peer's struct): */
133	int closed;     /* valid iff peer != NULL */
134	size_t len;     /* valid iff buf != NULL; 0 if peer == NULL */
135	size_t offset;  /* valid iff buf != NULL; 0 if len == 0 */
136	size_t size;
137	char *buf;      /* "size" elements (if != NULL) */
138
139	size_t request; /* valid iff peer != NULL; 0 if len != 0,
140	                 * otherwise set by peer to number of bytes
141	                 * it (unsuccessfully) tried to read,
142	                 * never more than buffer space (size-len) warrants. */
143};
144
145static int bio_new(BIO *bio)
146	{
147	struct bio_bio_st *b;
148
149	b = OPENSSL_malloc(sizeof *b);
150	if (b == NULL)
151		return 0;
152
153	b->peer = NULL;
154	b->size = 17*1024; /* enough for one TLS record (just a default) */
155	b->buf = NULL;
156
157	bio->ptr = b;
158	return 1;
159	}
160
161
162static int bio_free(BIO *bio)
163	{
164	struct bio_bio_st *b;
165
166	if (bio == NULL)
167		return 0;
168	b = bio->ptr;
169
170	assert(b != NULL);
171
172	if (b->peer)
173		bio_destroy_pair(bio);
174
175	if (b->buf != NULL)
176		{
177		OPENSSL_free(b->buf);
178		}
179
180	OPENSSL_free(b);
181
182	return 1;
183	}
184
185
186
187static int bio_read(BIO *bio, char *buf, int size_)
188	{
189	size_t size = size_;
190	size_t rest;
191	struct bio_bio_st *b, *peer_b;
192
193	BIO_clear_retry_flags(bio);
194
195	if (!bio->init)
196		return 0;
197
198	b = bio->ptr;
199	assert(b != NULL);
200	assert(b->peer != NULL);
201	peer_b = b->peer->ptr;
202	assert(peer_b != NULL);
203	assert(peer_b->buf != NULL);
204
205	peer_b->request = 0; /* will be set in "retry_read" situation */
206
207	if (buf == NULL || size == 0)
208		return 0;
209
210	if (peer_b->len == 0)
211		{
212		if (peer_b->closed)
213			return 0; /* writer has closed, and no data is left */
214		else
215			{
216			BIO_set_retry_read(bio); /* buffer is empty */
217			if (size <= peer_b->size)
218				peer_b->request = size;
219			else
220				/* don't ask for more than the peer can
221				 * deliver in one write */
222				peer_b->request = peer_b->size;
223			return -1;
224			}
225		}
226
227	/* we can read */
228	if (peer_b->len < size)
229		size = peer_b->len;
230
231	/* now read "size" bytes */
232
233	rest = size;
234
235	assert(rest > 0);
236	do /* one or two iterations */
237		{
238		size_t chunk;
239
240		assert(rest <= peer_b->len);
241		if (peer_b->offset + rest <= peer_b->size)
242			chunk = rest;
243		else
244			/* wrap around ring buffer */
245			chunk = peer_b->size - peer_b->offset;
246		assert(peer_b->offset + chunk <= peer_b->size);
247
248		memcpy(buf, peer_b->buf + peer_b->offset, chunk);
249
250		peer_b->len -= chunk;
251		if (peer_b->len)
252			{
253			peer_b->offset += chunk;
254			assert(peer_b->offset <= peer_b->size);
255			if (peer_b->offset == peer_b->size)
256				peer_b->offset = 0;
257			buf += chunk;
258			}
259		else
260			{
261			/* buffer now empty, no need to advance "buf" */
262			assert(chunk == rest);
263			peer_b->offset = 0;
264			}
265		rest -= chunk;
266		}
267	while (rest);
268
269	return size;
270	}
271
272/* non-copying interface: provide pointer to available data in buffer
273 *    bio_nread0:  return number of available bytes
274 *    bio_nread:   also advance index
275 * (example usage:  bio_nread0(), read from buffer, bio_nread()
276 *  or just         bio_nread(), read from buffer)
277 */
278/* WARNING: The non-copying interface is largely untested as of yet
279 * and may contain bugs. */
280static ossl_ssize_t bio_nread0(BIO *bio, char **buf)
281	{
282	struct bio_bio_st *b, *peer_b;
283	ossl_ssize_t num;
284
285	BIO_clear_retry_flags(bio);
286
287	if (!bio->init)
288		return 0;
289
290	b = bio->ptr;
291	assert(b != NULL);
292	assert(b->peer != NULL);
293	peer_b = b->peer->ptr;
294	assert(peer_b != NULL);
295	assert(peer_b->buf != NULL);
296
297	peer_b->request = 0;
298
299	if (peer_b->len == 0)
300		{
301		char dummy;
302
303		/* avoid code duplication -- nothing available for reading */
304		return bio_read(bio, &dummy, 1); /* returns 0 or -1 */
305		}
306
307	num = peer_b->len;
308	if (peer_b->size < peer_b->offset + num)
309		/* no ring buffer wrap-around for non-copying interface */
310		num = peer_b->size - peer_b->offset;
311	assert(num > 0);
312
313	if (buf != NULL)
314		*buf = peer_b->buf + peer_b->offset;
315	return num;
316	}
317
318static ossl_ssize_t bio_nread(BIO *bio, char **buf, size_t num_)
319	{
320	struct bio_bio_st *b, *peer_b;
321	ossl_ssize_t num, available;
322
323	if (num_ > SSIZE_MAX)
324		num = SSIZE_MAX;
325	else
326		num = (ossl_ssize_t)num_;
327
328	available = bio_nread0(bio, buf);
329	if (num > available)
330		num = available;
331	if (num <= 0)
332		return num;
333
334	b = bio->ptr;
335	peer_b = b->peer->ptr;
336
337	peer_b->len -= num;
338	if (peer_b->len)
339		{
340		peer_b->offset += num;
341		assert(peer_b->offset <= peer_b->size);
342		if (peer_b->offset == peer_b->size)
343			peer_b->offset = 0;
344		}
345	else
346		peer_b->offset = 0;
347
348	return num;
349	}
350
351
352static int bio_write(BIO *bio, const char *buf, int num_)
353	{
354	size_t num = num_;
355	size_t rest;
356	struct bio_bio_st *b;
357
358	BIO_clear_retry_flags(bio);
359
360	if (!bio->init || buf == NULL || num == 0)
361		return 0;
362
363	b = bio->ptr;
364	assert(b != NULL);
365	assert(b->peer != NULL);
366	assert(b->buf != NULL);
367
368	b->request = 0;
369	if (b->closed)
370		{
371		/* we already closed */
372		BIOerr(BIO_F_BIO_WRITE, BIO_R_BROKEN_PIPE);
373		return -1;
374		}
375
376	assert(b->len <= b->size);
377
378	if (b->len == b->size)
379		{
380		BIO_set_retry_write(bio); /* buffer is full */
381		return -1;
382		}
383
384	/* we can write */
385	if (num > b->size - b->len)
386		num = b->size - b->len;
387
388	/* now write "num" bytes */
389
390	rest = num;
391
392	assert(rest > 0);
393	do /* one or two iterations */
394		{
395		size_t write_offset;
396		size_t chunk;
397
398		assert(b->len + rest <= b->size);
399
400		write_offset = b->offset + b->len;
401		if (write_offset >= b->size)
402			write_offset -= b->size;
403		/* b->buf[write_offset] is the first byte we can write to. */
404
405		if (write_offset + rest <= b->size)
406			chunk = rest;
407		else
408			/* wrap around ring buffer */
409			chunk = b->size - write_offset;
410
411		memcpy(b->buf + write_offset, buf, chunk);
412
413		b->len += chunk;
414
415		assert(b->len <= b->size);
416
417		rest -= chunk;
418		buf += chunk;
419		}
420	while (rest);
421
422	return num;
423	}
424
425/* non-copying interface: provide pointer to region to write to
426 *   bio_nwrite0:  check how much space is available
427 *   bio_nwrite:   also increase length
428 * (example usage:  bio_nwrite0(), write to buffer, bio_nwrite()
429 *  or just         bio_nwrite(), write to buffer)
430 */
431static ossl_ssize_t bio_nwrite0(BIO *bio, char **buf)
432	{
433	struct bio_bio_st *b;
434	size_t num;
435	size_t write_offset;
436
437	BIO_clear_retry_flags(bio);
438
439	if (!bio->init)
440		return 0;
441
442	b = bio->ptr;
443	assert(b != NULL);
444	assert(b->peer != NULL);
445	assert(b->buf != NULL);
446
447	b->request = 0;
448	if (b->closed)
449		{
450		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_BROKEN_PIPE);
451		return -1;
452		}
453
454	assert(b->len <= b->size);
455
456	if (b->len == b->size)
457		{
458		BIO_set_retry_write(bio);
459		return -1;
460		}
461
462	num = b->size - b->len;
463	write_offset = b->offset + b->len;
464	if (write_offset >= b->size)
465		write_offset -= b->size;
466	if (write_offset + num > b->size)
467		/* no ring buffer wrap-around for non-copying interface
468		 * (to fulfil the promise by BIO_ctrl_get_write_guarantee,
469		 * BIO_nwrite may have to be called twice) */
470		num = b->size - write_offset;
471
472	if (buf != NULL)
473		*buf = b->buf + write_offset;
474	assert(write_offset + num <= b->size);
475
476	return num;
477	}
478
479static ossl_ssize_t bio_nwrite(BIO *bio, char **buf, size_t num_)
480	{
481	struct bio_bio_st *b;
482	ossl_ssize_t num, space;
483
484	if (num_ > SSIZE_MAX)
485		num = SSIZE_MAX;
486	else
487		num = (ossl_ssize_t)num_;
488
489	space = bio_nwrite0(bio, buf);
490	if (num > space)
491		num = space;
492	if (num <= 0)
493		return num;
494	b = bio->ptr;
495	assert(b != NULL);
496	b->len += num;
497	assert(b->len <= b->size);
498
499	return num;
500	}
501
502
503static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr)
504	{
505	long ret;
506	struct bio_bio_st *b = bio->ptr;
507
508	assert(b != NULL);
509
510	switch (cmd)
511		{
512	/* specific CTRL codes */
513
514	case BIO_C_SET_WRITE_BUF_SIZE:
515		if (b->peer)
516			{
517			BIOerr(BIO_F_BIO_CTRL, BIO_R_IN_USE);
518			ret = 0;
519			}
520		else if (num == 0)
521			{
522			BIOerr(BIO_F_BIO_CTRL, BIO_R_INVALID_ARGUMENT);
523			ret = 0;
524			}
525		else
526			{
527			size_t new_size = num;
528
529			if (b->size != new_size)
530				{
531				if (b->buf)
532					{
533					OPENSSL_free(b->buf);
534					b->buf = NULL;
535					}
536				b->size = new_size;
537				}
538			ret = 1;
539			}
540		break;
541
542	case BIO_C_GET_WRITE_BUF_SIZE:
543		ret = (long) b->size;
544		break;
545
546	case BIO_C_MAKE_BIO_PAIR:
547		{
548		BIO *other_bio = ptr;
549
550		if (bio_make_pair(bio, other_bio))
551			ret = 1;
552		else
553			ret = 0;
554		}
555		break;
556
557	case BIO_C_DESTROY_BIO_PAIR:
558		/* Affects both BIOs in the pair -- call just once!
559		 * Or let BIO_free(bio1); BIO_free(bio2); do the job. */
560		bio_destroy_pair(bio);
561		ret = 1;
562		break;
563
564	case BIO_C_GET_WRITE_GUARANTEE:
565		/* How many bytes can the caller feed to the next write
566		 * without having to keep any? */
567		if (b->peer == NULL || b->closed)
568			ret = 0;
569		else
570			ret = (long) b->size - b->len;
571		break;
572
573	case BIO_C_GET_READ_REQUEST:
574		/* If the peer unsuccessfully tried to read, how many bytes
575		 * were requested?  (As with BIO_CTRL_PENDING, that number
576		 * can usually be treated as boolean.) */
577		ret = (long) b->request;
578		break;
579
580	case BIO_C_RESET_READ_REQUEST:
581		/* Reset request.  (Can be useful after read attempts
582		 * at the other side that are meant to be non-blocking,
583		 * e.g. when probing SSL_read to see if any data is
584		 * available.) */
585		b->request = 0;
586		ret = 1;
587		break;
588
589	case BIO_C_SHUTDOWN_WR:
590		/* similar to shutdown(..., SHUT_WR) */
591		b->closed = 1;
592		ret = 1;
593		break;
594
595	case BIO_C_NREAD0:
596		/* prepare for non-copying read */
597		ret = (long) bio_nread0(bio, ptr);
598		break;
599
600	case BIO_C_NREAD:
601		/* non-copying read */
602		ret = (long) bio_nread(bio, ptr, (size_t) num);
603		break;
604
605	case BIO_C_NWRITE0:
606		/* prepare for non-copying write */
607		ret = (long) bio_nwrite0(bio, ptr);
608		break;
609
610	case BIO_C_NWRITE:
611		/* non-copying write */
612		ret = (long) bio_nwrite(bio, ptr, (size_t) num);
613		break;
614
615
616	/* standard CTRL codes follow */
617
618	case BIO_CTRL_RESET:
619		if (b->buf != NULL)
620			{
621			b->len = 0;
622			b->offset = 0;
623			}
624		ret = 0;
625		break;
626
627	case BIO_CTRL_GET_CLOSE:
628		ret = bio->shutdown;
629		break;
630
631	case BIO_CTRL_SET_CLOSE:
632		bio->shutdown = (int) num;
633		ret = 1;
634		break;
635
636	case BIO_CTRL_PENDING:
637		if (b->peer != NULL)
638			{
639			struct bio_bio_st *peer_b = b->peer->ptr;
640
641			ret = (long) peer_b->len;
642			}
643		else
644			ret = 0;
645		break;
646
647	case BIO_CTRL_WPENDING:
648		if (b->buf != NULL)
649			ret = (long) b->len;
650		else
651			ret = 0;
652		break;
653
654	case BIO_CTRL_DUP:
655		/* See BIO_dup_chain for circumstances we have to expect. */
656		{
657		BIO *other_bio = ptr;
658		struct bio_bio_st *other_b;
659
660		assert(other_bio != NULL);
661		other_b = other_bio->ptr;
662		assert(other_b != NULL);
663
664		assert(other_b->buf == NULL); /* other_bio is always fresh */
665
666		other_b->size = b->size;
667		}
668
669		ret = 1;
670		break;
671
672	case BIO_CTRL_FLUSH:
673		ret = 1;
674		break;
675
676	case BIO_CTRL_EOF:
677		{
678		BIO *other_bio = ptr;
679
680		if (other_bio)
681			{
682			struct bio_bio_st *other_b = other_bio->ptr;
683
684			assert(other_b != NULL);
685			ret = other_b->len == 0 && other_b->closed;
686			}
687		else
688			ret = 1;
689		}
690		break;
691
692	default:
693		ret = 0;
694		}
695	return ret;
696	}
697
698static int bio_puts(BIO *bio, const char *str)
699	{
700	return bio_write(bio, str, strlen(str));
701	}
702
703
704static int bio_make_pair(BIO *bio1, BIO *bio2)
705	{
706	struct bio_bio_st *b1, *b2;
707
708	assert(bio1 != NULL);
709	assert(bio2 != NULL);
710
711	b1 = bio1->ptr;
712	b2 = bio2->ptr;
713
714	if (b1->peer != NULL || b2->peer != NULL)
715		{
716		BIOerr(BIO_F_BIO_MAKE_PAIR, BIO_R_IN_USE);
717		return 0;
718		}
719
720	if (b1->buf == NULL)
721		{
722		b1->buf = OPENSSL_malloc(b1->size);
723		if (b1->buf == NULL)
724			{
725			BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);
726			return 0;
727			}
728		b1->len = 0;
729		b1->offset = 0;
730		}
731
732	if (b2->buf == NULL)
733		{
734		b2->buf = OPENSSL_malloc(b2->size);
735		if (b2->buf == NULL)
736			{
737			BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);
738			return 0;
739			}
740		b2->len = 0;
741		b2->offset = 0;
742		}
743
744	b1->peer = bio2;
745	b1->closed = 0;
746	b1->request = 0;
747	b2->peer = bio1;
748	b2->closed = 0;
749	b2->request = 0;
750
751	bio1->init = 1;
752	bio2->init = 1;
753
754	return 1;
755	}
756
757static void bio_destroy_pair(BIO *bio)
758	{
759	struct bio_bio_st *b = bio->ptr;
760
761	if (b != NULL)
762		{
763		BIO *peer_bio = b->peer;
764
765		if (peer_bio != NULL)
766			{
767			struct bio_bio_st *peer_b = peer_bio->ptr;
768
769			assert(peer_b != NULL);
770			assert(peer_b->peer == bio);
771
772			peer_b->peer = NULL;
773			peer_bio->init = 0;
774			assert(peer_b->buf != NULL);
775			peer_b->len = 0;
776			peer_b->offset = 0;
777
778			b->peer = NULL;
779			bio->init = 0;
780			assert(b->buf != NULL);
781			b->len = 0;
782			b->offset = 0;
783			}
784		}
785	}
786
787
788/* Exported convenience functions */
789int BIO_new_bio_pair(BIO **bio1_p, size_t writebuf1,
790	BIO **bio2_p, size_t writebuf2)
791	 {
792	 BIO *bio1 = NULL, *bio2 = NULL;
793	 long r;
794	 int ret = 0;
795
796	 bio1 = BIO_new(BIO_s_bio());
797	 if (bio1 == NULL)
798		 goto err;
799	 bio2 = BIO_new(BIO_s_bio());
800	 if (bio2 == NULL)
801		 goto err;
802
803	 if (writebuf1)
804		 {
805		 r = BIO_set_write_buf_size(bio1, writebuf1);
806		 if (!r)
807			 goto err;
808		 }
809	 if (writebuf2)
810		 {
811		 r = BIO_set_write_buf_size(bio2, writebuf2);
812		 if (!r)
813			 goto err;
814		 }
815
816	 r = BIO_make_bio_pair(bio1, bio2);
817	 if (!r)
818		 goto err;
819	 ret = 1;
820
821 err:
822	 if (ret == 0)
823		 {
824		 if (bio1)
825			 {
826			 BIO_free(bio1);
827			 bio1 = NULL;
828			 }
829		 if (bio2)
830			 {
831			 BIO_free(bio2);
832			 bio2 = NULL;
833			 }
834		 }
835
836	 *bio1_p = bio1;
837	 *bio2_p = bio2;
838	 return ret;
839	 }
840
841size_t BIO_ctrl_get_write_guarantee(BIO *bio)
842	{
843	return BIO_ctrl(bio, BIO_C_GET_WRITE_GUARANTEE, 0, NULL);
844	}
845
846size_t BIO_ctrl_get_read_request(BIO *bio)
847	{
848	return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);
849	}
850
851int BIO_ctrl_reset_read_request(BIO *bio)
852	{
853	return (BIO_ctrl(bio, BIO_C_RESET_READ_REQUEST, 0, NULL) != 0);
854	}
855
856
857/* BIO_nread0/nread/nwrite0/nwrite are available only for BIO pairs for now
858 * (conceivably some other BIOs could allow non-copying reads and writes too.)
859 */
860int BIO_nread0(BIO *bio, char **buf)
861	{
862	long ret;
863
864	if (!bio->init)
865		{
866		BIOerr(BIO_F_BIO_NREAD0, BIO_R_UNINITIALIZED);
867		return -2;
868		}
869
870	ret = BIO_ctrl(bio, BIO_C_NREAD0, 0, buf);
871	if (ret > INT_MAX)
872		return INT_MAX;
873	else
874		return (int) ret;
875	}
876
877int BIO_nread(BIO *bio, char **buf, int num)
878	{
879	int ret;
880
881	if (!bio->init)
882		{
883		BIOerr(BIO_F_BIO_NREAD, BIO_R_UNINITIALIZED);
884		return -2;
885		}
886
887	ret = (int) BIO_ctrl(bio, BIO_C_NREAD, num, buf);
888	if (ret > 0)
889		bio->num_read += ret;
890	return ret;
891	}
892
893int BIO_nwrite0(BIO *bio, char **buf)
894	{
895	long ret;
896
897	if (!bio->init)
898		{
899		BIOerr(BIO_F_BIO_NWRITE0, BIO_R_UNINITIALIZED);
900		return -2;
901		}
902
903	ret = BIO_ctrl(bio, BIO_C_NWRITE0, 0, buf);
904	if (ret > INT_MAX)
905		return INT_MAX;
906	else
907		return (int) ret;
908	}
909
910int BIO_nwrite(BIO *bio, char **buf, int num)
911	{
912	int ret;
913
914	if (!bio->init)
915		{
916		BIOerr(BIO_F_BIO_NWRITE, BIO_R_UNINITIALIZED);
917		return -2;
918		}
919
920	ret = BIO_ctrl(bio, BIO_C_NWRITE, num, buf);
921	if (ret > 0)
922		bio->num_write += ret;
923	return ret;
924	}
925