crypto/openssl/crypto/bio/bss_bio.c

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