text: /* crypto/bio/bf_nbio.c */
  /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   * All rights reserved.
   *
   * This package is an SSL implementation written
   * by Eric Young (eay@cryptsoft.com).
   * The implementation was written so as to conform with Netscapes SSL.
   * 
   * This library is free for commercial and non-commercial use as long as
   * the following conditions are aheared to.  The following conditions
   * apply to all code found in this distribution, be it the RC4, RSA,
   * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
   * included with this distribution is covered by the same copyright terms
   * except that the holder is Tim Hudson (tjh@cryptsoft.com).
   * 
   * Copyright remains Eric Young's, and as such any Copyright notices in
   * the code are not to be removed.
   * If this package is used in a product, Eric Young should be given attribution
   * as the author of the parts of the library used.
   * This can be in the form of a textual message at program startup or
   * in documentation (online or textual) provided with the package.
   * 
   * 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 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 acknowledgement:
   *    "This product includes cryptographic software written by
   *     Eric Young (eay@cryptsoft.com)"
   *    The word 'cryptographic' can be left out if the rouines from the library
   *    being used are not cryptographic related :-).
   * 4. If you include any Windows specific code (or a derivative thereof) from 
   *    the apps directory (application code) you must include an acknowledgement:
   *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
   * 
   * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
   * ANY EXPRESS 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 AUTHOR OR 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.
   * 
   * The licence and distribution terms for any publically available version or
   * derivative of this code cannot be changed.  i.e. this code cannot simply be
   * copied and put under another distribution licence
   * [including the GNU Public Licence.]
   */
  
  #include "cryptlib.h"
  #include <openssl/rand.h>
  #include <openssl/bio.h>
  #ifdef OPENSSL_SYS_WINDOWS
  #include <stdio.h>
  #include <errno.h>
  #endif
  
  /* BIO_put and BIO_get both add to the digest,
   * BIO_gets returns the digest */
  
  static int nbiof_write(BIO *h,const char *buf,int num);
  static int nbiof_read(BIO *h,char *buf,int size);
  static int nbiof_puts(BIO *h,const char *str);
  static int nbiof_gets(BIO *h,char *str,int size);
  static long nbiof_ctrl(BIO *h,int cmd,long arg1,void *arg2);
  static int nbiof_new(BIO *h);
  static int nbiof_free(BIO *data);
  static long nbiof_callback_ctrl(BIO *h,int cmd,bio_info_cb *fp);
  typedef struct nbio_test_st
  	{
  	/* only set if we sent a 'should retry' error */
  	int lrn;
  	int lwn;
  	} NBIO_TEST;
  
  static BIO_METHOD methods_nbiof=
  	{
  	BIO_TYPE_NBIO_TEST,
  	"non-blocking IO test filter",
  	nbiof_write,
  	nbiof_read,
  	nbiof_puts,
  	nbiof_gets,
  	nbiof_ctrl,
  	nbiof_new,
  	nbiof_free,
  	nbiof_callback_ctrl,
  	};
  
  BIO_METHOD *BIO_f_nbio_test(void)
  	{
  	return(&methods_nbiof);
  	}
  
  static int nbiof_new(BIO *bi)
  	{
  	NBIO_TEST *nt;
  
  	if (!(nt=(NBIO_TEST *)OPENSSL_malloc(sizeof(NBIO_TEST)))) return(0);
  	nt->lrn= -1;
  	nt->lwn= -1;
  	bi->ptr=(char *)nt;
  	bi->init=1;
  	bi->flags=0;
  	return(1);
  	}
  
  static int nbiof_free(BIO *a)
  	{
  	if (a == NULL) return(0);
  	if (a->ptr != NULL)
  		OPENSSL_free(a->ptr);
  	a->ptr=NULL;
  	a->init=0;
  	a->flags=0;
  	return(1);
  	}
  	
  static int nbiof_read(BIO *b, char *out, int outl)
  	{
  	int ret=0;
  #if 1
  	int num;
  	unsigned char n;
  #endif
  
  	if (out == NULL) return(0);
  	if (b->next_bio == NULL) return(0);
  
  	BIO_clear_retry_flags(b);
  #if 1
  	RAND_pseudo_bytes(&n,1);
  	num=(n&0x07);
  
  	if (outl > num) outl=num;
  
  	if (num == 0)
  		{
  		ret= -1;
  		BIO_set_retry_read(b);
  		}
  	else
  #endif
  		{
  		ret=BIO_read(b->next_bio,out,outl);
  		if (ret < 0)
  			BIO_copy_next_retry(b);
  		}
  	return(ret);
  	}
  
  static int nbiof_write(BIO *b, const char *in, int inl)
  	{
  	NBIO_TEST *nt;
  	int ret=0;
  	int num;
  	unsigned char n;
  
  	if ((in == NULL) || (inl <= 0)) return(0);
  	if (b->next_bio == NULL) return(0);
  	nt=(NBIO_TEST *)b->ptr;
  
  	BIO_clear_retry_flags(b);
  
  #if 1
  	if (nt->lwn > 0)
  		{
  		num=nt->lwn;
  		nt->lwn=0;
  		}
  	else
  		{
  		RAND_pseudo_bytes(&n,1);
  		num=(n&7);
  		}
  
  	if (inl > num) inl=num;
  
  	if (num == 0)
  		{
  		ret= -1;
  		BIO_set_retry_write(b);
  		}
  	else
  #endif
  		{
  		ret=BIO_write(b->next_bio,in,inl);
  		if (ret < 0)
  			{
  			BIO_copy_next_retry(b);
  			nt->lwn=inl;
  			}
  		}
  	return(ret);
  	}
  
  static long nbiof_ctrl(BIO *b, int cmd, long num, void *ptr)
  	{
  	long ret;
  
  	if (b->next_bio == NULL) return(0);
  	switch (cmd)
  		{
          case BIO_C_DO_STATE_MACHINE:
  		BIO_clear_retry_flags(b);
  		ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
  		BIO_copy_next_retry(b);
  		break;
  	case BIO_CTRL_DUP:
  		ret=0L;
  		break;
  	default:
  		ret=BIO_ctrl(b->next_bio,cmd,num,ptr);
  		break;
  		}
  	return(ret);
  	}
  
  static long nbiof_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
  	{
  	long ret=1;
  
  	if (b->next_bio == NULL) return(0);
  	switch (cmd)
  		{
  	default:
  		ret=BIO_callback_ctrl(b->next_bio,cmd,fp);
  		break;
  		}
  	return(ret);
  	}
  
  static int nbiof_gets(BIO *bp, char *buf, int size)
  	{
  	if (bp->next_bio == NULL) return(0);
  	return(BIO_gets(bp->next_bio,buf,size));
  	}
  
  
  static int nbiof_puts(BIO *bp, const char *str)
  	{
  	if (bp->next_bio == NULL) return(0);
  	return(BIO_puts(bp->next_bio,str));
  	}
  
  
  