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bss_bio.c

/* crypto/bio/bss_bio.c  -*- Mode: C; c-file-style: "eay" -*- */
/* ====================================================================
 * Copyright (c) 1998-2003 The OpenSSL Project.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    openssl-core@openssl.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.openssl.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 * ====================================================================
 *
 * This product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */

/* Special method for a BIO where the other endpoint is also a BIO
 * of this kind, handled by the same thread (i.e. the "peer" is actually
 * ourselves, wearing a different hat).
 * Such "BIO pairs" are mainly for using the SSL library with I/O interfaces
 * for which no specific BIO method is available.
 * See ssl/ssltest.c for some hints on how this can be used. */

/* BIO_DEBUG implies BIO_PAIR_DEBUG */
#ifdef BIO_DEBUG
# ifndef BIO_PAIR_DEBUG
#  define BIO_PAIR_DEBUG
# endif
#endif

/* disable assert() unless BIO_PAIR_DEBUG has been defined */
#ifndef BIO_PAIR_DEBUG
# ifndef NDEBUG
#  define NDEBUG
# endif
#endif

#include <assert.h>
#include <limits.h>
#include <stdlib.h>
#include <string.h>

#include <openssl/bio.h>
#include <openssl/err.h>
#include <openssl/crypto.h>

#include "e_os.h"

/* VxWorks defines SSIZE_MAX with an empty value causing compile errors */
#if defined(OPENSSL_SYS_VXWORKS)
# undef SSIZE_MAX
#endif
#ifndef SSIZE_MAX
# define SSIZE_MAX INT_MAX
#endif

static int bio_new(BIO *bio);
static int bio_free(BIO *bio);
static int bio_read(BIO *bio, char *buf, int size);
static int bio_write(BIO *bio, const char *buf, int num);
static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr);
static int bio_puts(BIO *bio, const char *str);

static int bio_make_pair(BIO *bio1, BIO *bio2);
static void bio_destroy_pair(BIO *bio);

static BIO_METHOD methods_biop =
{
      BIO_TYPE_BIO,
      "BIO pair",
      bio_write,
      bio_read,
      bio_puts,
      NULL /* no bio_gets */,
      bio_ctrl,
      bio_new,
      bio_free,
      NULL /* no bio_callback_ctrl */
};

BIO_METHOD *BIO_s_bio(void)
      {
      return &methods_biop;
      }

struct bio_bio_st
{
      BIO *peer;     /* NULL if buf == NULL.
                      * If peer != NULL, then peer->ptr is also a bio_bio_st,
                      * and its "peer" member points back to us.
                      * peer != NULL iff init != 0 in the BIO. */
      
      /* This is for what we write (i.e. reading uses peer's struct): */
      int closed;     /* valid iff peer != NULL */
      size_t len;     /* valid iff buf != NULL; 0 if peer == NULL */
      size_t offset;  /* valid iff buf != NULL; 0 if len == 0 */
      size_t size;
      char *buf;      /* "size" elements (if != NULL) */

      size_t request; /* valid iff peer != NULL; 0 if len != 0,
                       * otherwise set by peer to number of bytes
                       * it (unsuccessfully) tried to read,
                       * never more than buffer space (size-len) warrants. */
};

static int bio_new(BIO *bio)
      {
      struct bio_bio_st *b;
      
      b = OPENSSL_malloc(sizeof *b);
      if (b == NULL)
            return 0;

      b->peer = NULL;
      b->size = 17*1024; /* enough for one TLS record (just a default) */
      b->buf = NULL;

      bio->ptr = b;
      return 1;
      }


static int bio_free(BIO *bio)
      {
      struct bio_bio_st *b;

      if (bio == NULL)
            return 0;
      b = bio->ptr;

      assert(b != NULL);

      if (b->peer)
            bio_destroy_pair(bio);
      
      if (b->buf != NULL)
            {
            OPENSSL_free(b->buf);
            }

      OPENSSL_free(b);

      return 1;
      }



static int bio_read(BIO *bio, char *buf, int size_)
      {
      size_t size = size_;
      size_t rest;
      struct bio_bio_st *b, *peer_b;

      BIO_clear_retry_flags(bio);

      if (!bio->init)
            return 0;

      b = bio->ptr;
      assert(b != NULL);
      assert(b->peer != NULL);
      peer_b = b->peer->ptr;
      assert(peer_b != NULL);
      assert(peer_b->buf != NULL);

      peer_b->request = 0; /* will be set in "retry_read" situation */

      if (buf == NULL || size == 0)
            return 0;

      if (peer_b->len == 0)
            {
            if (peer_b->closed)
                  return 0; /* writer has closed, and no data is left */
            else
                  {
                  BIO_set_retry_read(bio); /* buffer is empty */
                  if (size <= peer_b->size)
                        peer_b->request = size;
                  else
                        /* don't ask for more than the peer can
                         * deliver in one write */
                        peer_b->request = peer_b->size;
                  return -1;
                  }
            }

      /* we can read */
      if (peer_b->len < size)
            size = peer_b->len;

      /* now read "size" bytes */
      
      rest = size;
      
      assert(rest > 0);
      do /* one or two iterations */
            {
            size_t chunk;
            
            assert(rest <= peer_b->len);
            if (peer_b->offset + rest <= peer_b->size)
                  chunk = rest;
            else
                  /* wrap around ring buffer */
                  chunk = peer_b->size - peer_b->offset;
            assert(peer_b->offset + chunk <= peer_b->size);
            
            memcpy(buf, peer_b->buf + peer_b->offset, chunk);
            
            peer_b->len -= chunk;
            if (peer_b->len)
                  {
                  peer_b->offset += chunk;
                  assert(peer_b->offset <= peer_b->size);
                  if (peer_b->offset == peer_b->size)
                        peer_b->offset = 0;
                  buf += chunk;
                  }
            else
                  {
                  /* buffer now empty, no need to advance "buf" */
                  assert(chunk == rest);
                  peer_b->offset = 0;
                  }
            rest -= chunk;
            }
      while (rest);
      
      return size;
      }

/* non-copying interface: provide pointer to available data in buffer
 *    bio_nread0:  return number of available bytes
 *    bio_nread:   also advance index
 * (example usage:  bio_nread0(), read from buffer, bio_nread()
 *  or just         bio_nread(), read from buffer)
 */
/* WARNING: The non-copying interface is largely untested as of yet
 * and may contain bugs. */
static ssize_t bio_nread0(BIO *bio, char **buf)
      {
      struct bio_bio_st *b, *peer_b;
      ssize_t num;
      
      BIO_clear_retry_flags(bio);

      if (!bio->init)
            return 0;
      
      b = bio->ptr;
      assert(b != NULL);
      assert(b->peer != NULL);
      peer_b = b->peer->ptr;
      assert(peer_b != NULL);
      assert(peer_b->buf != NULL);
      
      peer_b->request = 0;
      
      if (peer_b->len == 0)
            {
            char dummy;
            
            /* avoid code duplication -- nothing available for reading */
            return bio_read(bio, &dummy, 1); /* returns 0 or -1 */
            }

      num = peer_b->len;
      if (peer_b->size < peer_b->offset + num)
            /* no ring buffer wrap-around for non-copying interface */
            num = peer_b->size - peer_b->offset;
      assert(num > 0);

      if (buf != NULL)
            *buf = peer_b->buf + peer_b->offset;
      return num;
      }

static ssize_t bio_nread(BIO *bio, char **buf, size_t num_)
      {
      struct bio_bio_st *b, *peer_b;
      ssize_t num, available;

      if (num_ > SSIZE_MAX)
            num = SSIZE_MAX;
      else
            num = (ssize_t)num_;

      available = bio_nread0(bio, buf);
      if (num > available)
            num = available;
      if (num <= 0)
            return num;

      b = bio->ptr;
      peer_b = b->peer->ptr;

      peer_b->len -= num;
      if (peer_b->len) 
            {
            peer_b->offset += num;
            assert(peer_b->offset <= peer_b->size);
            if (peer_b->offset == peer_b->size)
                  peer_b->offset = 0;
            }
      else
            peer_b->offset = 0;

      return num;
      }


static int bio_write(BIO *bio, const char *buf, int num_)
      {
      size_t num = num_;
      size_t rest;
      struct bio_bio_st *b;

      BIO_clear_retry_flags(bio);

      if (!bio->init || buf == NULL || num == 0)
            return 0;

      b = bio->ptr;           
      assert(b != NULL);
      assert(b->peer != NULL);
      assert(b->buf != NULL);

      b->request = 0;
      if (b->closed)
            {
            /* we already closed */
            BIOerr(BIO_F_BIO_WRITE, BIO_R_BROKEN_PIPE);
            return -1;
            }

      assert(b->len <= b->size);

      if (b->len == b->size)
            {
            BIO_set_retry_write(bio); /* buffer is full */
            return -1;
            }

      /* we can write */
      if (num > b->size - b->len)
            num = b->size - b->len;
      
      /* now write "num" bytes */

      rest = num;
      
      assert(rest > 0);
      do /* one or two iterations */
            {
            size_t write_offset;
            size_t chunk;

            assert(b->len + rest <= b->size);

            write_offset = b->offset + b->len;
            if (write_offset >= b->size)
                  write_offset -= b->size;
            /* b->buf[write_offset] is the first byte we can write to. */

            if (write_offset + rest <= b->size)
                  chunk = rest;
            else
                  /* wrap around ring buffer */
                  chunk = b->size - write_offset;
            
            memcpy(b->buf + write_offset, buf, chunk);
            
            b->len += chunk;

            assert(b->len <= b->size);
            
            rest -= chunk;
            buf += chunk;
            }
      while (rest);

      return num;
      }

/* non-copying interface: provide pointer to region to write to
 *   bio_nwrite0:  check how much space is available
 *   bio_nwrite:   also increase length
 * (example usage:  bio_nwrite0(), write to buffer, bio_nwrite()
 *  or just         bio_nwrite(), write to buffer)
 */
static ssize_t bio_nwrite0(BIO *bio, char **buf)
      {
      struct bio_bio_st *b;
      size_t num;
      size_t write_offset;

      BIO_clear_retry_flags(bio);

      if (!bio->init)
            return 0;

      b = bio->ptr;           
      assert(b != NULL);
      assert(b->peer != NULL);
      assert(b->buf != NULL);

      b->request = 0;
      if (b->closed)
            {
            BIOerr(BIO_F_BIO_NWRITE0, BIO_R_BROKEN_PIPE);
            return -1;
            }

      assert(b->len <= b->size);

      if (b->len == b->size)
            {
            BIO_set_retry_write(bio);
            return -1;
            }

      num = b->size - b->len;
      write_offset = b->offset + b->len;
      if (write_offset >= b->size)
            write_offset -= b->size;
      if (write_offset + num > b->size)
            /* no ring buffer wrap-around for non-copying interface
             * (to fulfil the promise by BIO_ctrl_get_write_guarantee,
             * BIO_nwrite may have to be called twice) */
            num = b->size - write_offset;

      if (buf != NULL)
            *buf = b->buf + write_offset;
      assert(write_offset + num <= b->size);

      return num;
      }

static ssize_t bio_nwrite(BIO *bio, char **buf, size_t num_)
      {
      struct bio_bio_st *b;
      ssize_t num, space;

      if (num_ > SSIZE_MAX)
            num = SSIZE_MAX;
      else
            num = (ssize_t)num_;

      space = bio_nwrite0(bio, buf);
      if (num > space)
            num = space;
      if (num <= 0)
            return num;
      b = bio->ptr;
      assert(b != NULL);
      b->len += num;
      assert(b->len <= b->size);

      return num;
      }


static long bio_ctrl(BIO *bio, int cmd, long num, void *ptr)
      {
      long ret;
      struct bio_bio_st *b = bio->ptr;
      
      assert(b != NULL);

      switch (cmd)
            {
      /* specific CTRL codes */

      case BIO_C_SET_WRITE_BUF_SIZE:
            if (b->peer)
                  {
                  BIOerr(BIO_F_BIO_CTRL, BIO_R_IN_USE);
                  ret = 0;
                  }
            else if (num == 0)
                  {
                  BIOerr(BIO_F_BIO_CTRL, BIO_R_INVALID_ARGUMENT);
                  ret = 0;
                  }
            else
                  {
                  size_t new_size = num;

                  if (b->size != new_size)
                        {
                        if (b->buf) 
                              {
                              OPENSSL_free(b->buf);
                              b->buf = NULL;
                              }
                        b->size = new_size;
                        }
                  ret = 1;
                  }
            break;

      case BIO_C_GET_WRITE_BUF_SIZE:
            ret = (long) b->size;
            break;

      case BIO_C_MAKE_BIO_PAIR:
            {
            BIO *other_bio = ptr;
            
            if (bio_make_pair(bio, other_bio))
                  ret = 1;
            else
                  ret = 0;
            }
            break;
            
      case BIO_C_DESTROY_BIO_PAIR:
            /* Affects both BIOs in the pair -- call just once!
             * Or let BIO_free(bio1); BIO_free(bio2); do the job. */
            bio_destroy_pair(bio);
            ret = 1;
            break;

      case BIO_C_GET_WRITE_GUARANTEE:
            /* How many bytes can the caller feed to the next write
             * without having to keep any? */
            if (b->peer == NULL || b->closed)
                  ret = 0;
            else
                  ret = (long) b->size - b->len;
            break;

      case BIO_C_GET_READ_REQUEST:
            /* If the peer unsuccessfully tried to read, how many bytes
             * were requested?  (As with BIO_CTRL_PENDING, that number
             * can usually be treated as boolean.) */
            ret = (long) b->request;
            break;

      case BIO_C_RESET_READ_REQUEST:
            /* Reset request.  (Can be useful after read attempts
             * at the other side that are meant to be non-blocking,
             * e.g. when probing SSL_read to see if any data is
             * available.) */
            b->request = 0;
            ret = 1;
            break;

      case BIO_C_SHUTDOWN_WR:
            /* similar to shutdown(..., SHUT_WR) */
            b->closed = 1;
            ret = 1;
            break;

      case BIO_C_NREAD0:
            /* prepare for non-copying read */
            ret = (long) bio_nread0(bio, ptr);
            break;
            
      case BIO_C_NREAD:
            /* non-copying read */
            ret = (long) bio_nread(bio, ptr, (size_t) num);
            break;
            
      case BIO_C_NWRITE0:
            /* prepare for non-copying write */
            ret = (long) bio_nwrite0(bio, ptr);
            break;

      case BIO_C_NWRITE:
            /* non-copying write */
            ret = (long) bio_nwrite(bio, ptr, (size_t) num);
            break;
            

      /* standard CTRL codes follow */

      case BIO_CTRL_RESET:
            if (b->buf != NULL)
                  {
                  b->len = 0;
                  b->offset = 0;
                  }
            ret = 0;
            break;            

      case BIO_CTRL_GET_CLOSE:
            ret = bio->shutdown;
            break;

      case BIO_CTRL_SET_CLOSE:
            bio->shutdown = (int) num;
            ret = 1;
            break;

      case BIO_CTRL_PENDING:
            if (b->peer != NULL)
                  {
                  struct bio_bio_st *peer_b = b->peer->ptr;
                  
                  ret = (long) peer_b->len;
                  }
            else
                  ret = 0;
            break;

      case BIO_CTRL_WPENDING:
            if (b->buf != NULL)
                  ret = (long) b->len;
            else
                  ret = 0;
            break;

      case BIO_CTRL_DUP:
            /* See BIO_dup_chain for circumstances we have to expect. */
            {
            BIO *other_bio = ptr;
            struct bio_bio_st *other_b;
            
            assert(other_bio != NULL);
            other_b = other_bio->ptr;
            assert(other_b != NULL);
            
            assert(other_b->buf == NULL); /* other_bio is always fresh */

            other_b->size = b->size;
            }

            ret = 1;
            break;

      case BIO_CTRL_FLUSH:
            ret = 1;
            break;

      case BIO_CTRL_EOF:
            {
            BIO *other_bio = ptr;
            
            if (other_bio)
                  {
                  struct bio_bio_st *other_b = other_bio->ptr;
                  
                  assert(other_b != NULL);
                  ret = other_b->len == 0 && other_b->closed;
                  }
            else
                  ret = 1;
            }
            break;

      default:
            ret = 0;
            }
      return ret;
      }

static int bio_puts(BIO *bio, const char *str)
      {
      return bio_write(bio, str, strlen(str));
      }


static int bio_make_pair(BIO *bio1, BIO *bio2)
      {
      struct bio_bio_st *b1, *b2;

      assert(bio1 != NULL);
      assert(bio2 != NULL);

      b1 = bio1->ptr;
      b2 = bio2->ptr;
      
      if (b1->peer != NULL || b2->peer != NULL)
            {
            BIOerr(BIO_F_BIO_MAKE_PAIR, BIO_R_IN_USE);
            return 0;
            }
      
      if (b1->buf == NULL)
            {
            b1->buf = OPENSSL_malloc(b1->size);
            if (b1->buf == NULL)
                  {
                  BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);
                  return 0;
                  }
            b1->len = 0;
            b1->offset = 0;
            }
      
      if (b2->buf == NULL)
            {
            b2->buf = OPENSSL_malloc(b2->size);
            if (b2->buf == NULL)
                  {
                  BIOerr(BIO_F_BIO_MAKE_PAIR, ERR_R_MALLOC_FAILURE);
                  return 0;
                  }
            b2->len = 0;
            b2->offset = 0;
            }
      
      b1->peer = bio2;
      b1->closed = 0;
      b1->request = 0;
      b2->peer = bio1;
      b2->closed = 0;
      b2->request = 0;

      bio1->init = 1;
      bio2->init = 1;

      return 1;
      }

static void bio_destroy_pair(BIO *bio)
      {
      struct bio_bio_st *b = bio->ptr;

      if (b != NULL)
            {
            BIO *peer_bio = b->peer;

            if (peer_bio != NULL)
                  {
                  struct bio_bio_st *peer_b = peer_bio->ptr;

                  assert(peer_b != NULL);
                  assert(peer_b->peer == bio);

                  peer_b->peer = NULL;
                  peer_bio->init = 0;
                  assert(peer_b->buf != NULL);
                  peer_b->len = 0;
                  peer_b->offset = 0;
                  
                  b->peer = NULL;
                  bio->init = 0;
                  assert(b->buf != NULL);
                  b->len = 0;
                  b->offset = 0;
                  }
            }
      }
 

/* Exported convenience functions */
int BIO_new_bio_pair(BIO **bio1_p, size_t writebuf1,
      BIO **bio2_p, size_t writebuf2)
       {
       BIO *bio1 = NULL, *bio2 = NULL;
       long r;
       int ret = 0;

       bio1 = BIO_new(BIO_s_bio());
       if (bio1 == NULL)
             goto err;
       bio2 = BIO_new(BIO_s_bio());
       if (bio2 == NULL)
             goto err;

       if (writebuf1)
             {
             r = BIO_set_write_buf_size(bio1, writebuf1);
             if (!r)
                   goto err;
             }
       if (writebuf2)
             {
             r = BIO_set_write_buf_size(bio2, writebuf2);
             if (!r)
                   goto err;
             }

       r = BIO_make_bio_pair(bio1, bio2);
       if (!r)
             goto err;
       ret = 1;

 err:
       if (ret == 0)
             {
             if (bio1)
                   {
                   BIO_free(bio1);
                   bio1 = NULL;
                   }
             if (bio2)
                   {
                   BIO_free(bio2);
                   bio2 = NULL;
                   }
             }

       *bio1_p = bio1;
       *bio2_p = bio2;
       return ret;
       }

size_t BIO_ctrl_get_write_guarantee(BIO *bio)
      {
      return BIO_ctrl(bio, BIO_C_GET_WRITE_GUARANTEE, 0, NULL);
      }

size_t BIO_ctrl_get_read_request(BIO *bio)
      {
      return BIO_ctrl(bio, BIO_C_GET_READ_REQUEST, 0, NULL);
      }

int BIO_ctrl_reset_read_request(BIO *bio)
      {
      return (BIO_ctrl(bio, BIO_C_RESET_READ_REQUEST, 0, NULL) != 0);
      }


/* BIO_nread0/nread/nwrite0/nwrite are available only for BIO pairs for now
 * (conceivably some other BIOs could allow non-copying reads and writes too.)
 */
int BIO_nread0(BIO *bio, char **buf)
      {
      long ret;

      if (!bio->init)
            {
            BIOerr(BIO_F_BIO_NREAD0, BIO_R_UNINITIALIZED);
            return -2;
            }

      ret = BIO_ctrl(bio, BIO_C_NREAD0, 0, buf);
      if (ret > INT_MAX)
            return INT_MAX;
      else
            return (int) ret;
      }

int BIO_nread(BIO *bio, char **buf, int num)
      {
      int ret;

      if (!bio->init)
            {
            BIOerr(BIO_F_BIO_NREAD, BIO_R_UNINITIALIZED);
            return -2;
            }

      ret = (int) BIO_ctrl(bio, BIO_C_NREAD, num, buf);
      if (ret > 0)
            bio->num_read += ret;
      return ret;
      }

int BIO_nwrite0(BIO *bio, char **buf)
      {
      long ret;

      if (!bio->init)
            {
            BIOerr(BIO_F_BIO_NWRITE0, BIO_R_UNINITIALIZED);
            return -2;
            }

      ret = BIO_ctrl(bio, BIO_C_NWRITE0, 0, buf);
      if (ret > INT_MAX)
            return INT_MAX;
      else
            return (int) ret;
      }

int BIO_nwrite(BIO *bio, char **buf, int num)
      {
      int ret;

      if (!bio->init)
            {
            BIOerr(BIO_F_BIO_NWRITE, BIO_R_UNINITIALIZED);
            return -2;
            }

      ret = BIO_ctrl(bio, BIO_C_NWRITE, num, buf);
      if (ret > 0)
            bio->num_read += ret;
      return ret;
      }

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