text: /* crypto/evp/bio_md.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 <stdio.h>
  #include <errno.h>
  #include "cryptlib.h"
  #include <openssl/buffer.h>
  #include <openssl/evp.h>
  
  /*
   * BIO_put and BIO_get both add to the digest, BIO_gets returns the digest
   */
  
  static int md_write(BIO *h, char const *buf, int num);
  static int md_read(BIO *h, char *buf, int size);
  /*
   * static int md_puts(BIO *h, const char *str);
   */
  static int md_gets(BIO *h, char *str, int size);
  static long md_ctrl(BIO *h, int cmd, long arg1, void *arg2);
  static int md_new(BIO *h);
  static int md_free(BIO *data);
  static long md_callback_ctrl(BIO *h, int cmd, bio_info_cb *fp);
  
  static BIO_METHOD methods_md = {
      BIO_TYPE_MD, "message digest",
      md_write,
      md_read,
      NULL,                       /* md_puts, */
      md_gets,
      md_ctrl,
      md_new,
      md_free,
      md_callback_ctrl,
  };
  
  BIO_METHOD *BIO_f_md(void)
  {
      return (&methods_md);
  }
  
  static int md_new(BIO *bi)
  {
      EVP_MD_CTX *ctx;
  
      ctx = EVP_MD_CTX_create();
      if (ctx == NULL)
          return (0);
  
      bi->init = 0;
      bi->ptr = (char *)ctx;
      bi->flags = 0;
      return (1);
  }
  
  static int md_free(BIO *a)
  {
      if (a == NULL)
          return (0);
      EVP_MD_CTX_destroy(a->ptr);
      a->ptr = NULL;
      a->init = 0;
      a->flags = 0;
      return (1);
  }
  
  static int md_read(BIO *b, char *out, int outl)
  {
      int ret = 0;
      EVP_MD_CTX *ctx;
  
      if (out == NULL)
          return (0);
      ctx = b->ptr;
  
      if ((ctx == NULL) || (b->next_bio == NULL))
          return (0);
  
      ret = BIO_read(b->next_bio, out, outl);
      if (b->init) {
          if (ret > 0) {
              if (EVP_DigestUpdate(ctx, (unsigned char *)out,
                                   (unsigned int)ret) <= 0)
                  return (-1);
          }
      }
      BIO_clear_retry_flags(b);
      BIO_copy_next_retry(b);
      return (ret);
  }
  
  static int md_write(BIO *b, const char *in, int inl)
  {
      int ret = 0;
      EVP_MD_CTX *ctx;
  
      if ((in == NULL) || (inl <= 0))
          return (0);
      ctx = b->ptr;
  
      if ((ctx != NULL) && (b->next_bio != NULL))
          ret = BIO_write(b->next_bio, in, inl);
      if (b->init) {
          if (ret > 0) {
              if (!EVP_DigestUpdate(ctx, (const unsigned char *)in,
                                    (unsigned int)ret)) {
                  BIO_clear_retry_flags(b);
                  return 0;
              }
          }
      }
      if (b->next_bio != NULL) {
          BIO_clear_retry_flags(b);
          BIO_copy_next_retry(b);
      }
      return (ret);
  }
  
  static long md_ctrl(BIO *b, int cmd, long num, void *ptr)
  {
      EVP_MD_CTX *ctx, *dctx, **pctx;
      const EVP_MD **ppmd;
      EVP_MD *md;
      long ret = 1;
      BIO *dbio;
  
      ctx = b->ptr;
  
      switch (cmd) {
      case BIO_CTRL_RESET:
          if (b->init)
              ret = EVP_DigestInit_ex(ctx, ctx->digest, NULL);
          else
              ret = 0;
          if (ret > 0)
              ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
          break;
      case BIO_C_GET_MD:
          if (b->init) {
              ppmd = ptr;
              *ppmd = ctx->digest;
          } else
              ret = 0;
          break;
      case BIO_C_GET_MD_CTX:
          pctx = ptr;
          *pctx = ctx;
          b->init = 1;
          break;
      case BIO_C_SET_MD_CTX:
          if (b->init)
              b->ptr = ptr;
          else
              ret = 0;
          break;
      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_C_SET_MD:
          md = ptr;
          ret = EVP_DigestInit_ex(ctx, md, NULL);
          if (ret > 0)
              b->init = 1;
          break;
      case BIO_CTRL_DUP:
          dbio = ptr;
          dctx = dbio->ptr;
          if (!EVP_MD_CTX_copy_ex(dctx, ctx))
              return 0;
          b->init = 1;
          break;
      default:
          ret = BIO_ctrl(b->next_bio, cmd, num, ptr);
          break;
      }
      return (ret);
  }
  
  static long md_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 md_gets(BIO *bp, char *buf, int size)
  {
      EVP_MD_CTX *ctx;
      unsigned int ret;
  
      ctx = bp->ptr;
      if (size < ctx->digest->md_size)
          return (0);
      if (EVP_DigestFinal_ex(ctx, (unsigned char *)buf, &ret) <= 0)
          return -1;
  
      return ((int)ret);
  }
  
  /*-
  static int md_puts(bp,str)
  BIO *bp;
  char *str;
          {
          return(-1);
          }
  */
  