text: /*
   * Copyright 1995-2016 The OpenSSL Project Authors. All Rights Reserved.
   *
   * Licensed under the OpenSSL license (the "License").  You may not use
   * this file except in compliance with the License.  You can obtain a copy
   * in the file LICENSE in the source distribution or at
   * https://www.openssl.org/source/license.html
   */
  
  #include <stdio.h>
  #include <errno.h>
  #include "internal/cryptlib.h"
  #include <openssl/buffer.h>
  #include <openssl/evp.h>
  #include "internal/evp_int.h"
  #include "evp_locl.h"
  #include "internal/bio.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 const 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,
  };
  
  const BIO_METHOD *BIO_f_md(void)
  {
      return (&methods_md);
  }
  
  static int md_new(BIO *bi)
  {
      EVP_MD_CTX *ctx;
  
      ctx = EVP_MD_CTX_new();
      if (ctx == NULL)
          return (0);
  
      BIO_set_init(bi, 1);
      BIO_set_data(bi, ctx);
  
      return 1;
  }
  
  static int md_free(BIO *a)
  {
      if (a == NULL)
          return (0);
      EVP_MD_CTX_free(BIO_get_data(a));
      BIO_set_data(a, NULL);
      BIO_set_init(a, 0);
  
      return 1;
  }
  
  static int md_read(BIO *b, char *out, int outl)
  {
      int ret = 0;
      EVP_MD_CTX *ctx;
      BIO *next;
  
      if (out == NULL)
          return (0);
  
      ctx = BIO_get_data(b);
      next = BIO_next(b);
  
      if ((ctx == NULL) || (next == NULL))
          return (0);
  
      ret = BIO_read(next, out, outl);
      if (BIO_get_init(b)) {
          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;
      BIO *next;
  
      if ((in == NULL) || (inl <= 0))
          return 0;
  
      ctx = BIO_get_data(b);
      next = BIO_next(b);
      if ((ctx != NULL) && (next != NULL))
          ret = BIO_write(next, in, inl);
  
      if (BIO_get_init(b)) {
          if (ret > 0) {
              if (!EVP_DigestUpdate(ctx, (const unsigned char *)in,
                                    (unsigned int)ret)) {
                  BIO_clear_retry_flags(b);
                  return 0;
              }
          }
      }
      if (next != 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, *next;
  
  
      ctx = BIO_get_data(b);
      next = BIO_next(b);
  
      switch (cmd) {
      case BIO_CTRL_RESET:
          if (BIO_get_init(b))
              ret = EVP_DigestInit_ex(ctx, ctx->digest, NULL);
          else
              ret = 0;
          if (ret > 0)
              ret = BIO_ctrl(next, cmd, num, ptr);
          break;
      case BIO_C_GET_MD:
          if (BIO_get_init(b)) {
              ppmd = ptr;
              *ppmd = ctx->digest;
          } else
              ret = 0;
          break;
      case BIO_C_GET_MD_CTX:
          pctx = ptr;
          *pctx = ctx;
          BIO_set_init(b, 1);
          break;
      case BIO_C_SET_MD_CTX:
          if (BIO_get_init(b))
              BIO_set_data(b, ptr);
          else
              ret = 0;
          break;
      case BIO_C_DO_STATE_MACHINE:
          BIO_clear_retry_flags(b);
          ret = BIO_ctrl(next, 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)
              BIO_set_init(b, 1);
          break;
      case BIO_CTRL_DUP:
          dbio = ptr;
          dctx = BIO_get_data(dbio);
          if (!EVP_MD_CTX_copy_ex(dctx, ctx))
              return 0;
          BIO_set_init(b, 1);
          break;
      default:
          ret = BIO_ctrl(next, cmd, num, ptr);
          break;
      }
      return (ret);
  }
  
  static long md_callback_ctrl(BIO *b, int cmd, bio_info_cb *fp)
  {
      long ret = 1;
      BIO *next;
  
      next = BIO_next(b);
  
      if (next == NULL)
          return 0;
  
      switch (cmd) {
      default:
          ret = BIO_callback_ctrl(next, cmd, fp);
          break;
      }
      return (ret);
  }
  
  static int md_gets(BIO *bp, char *buf, int size)
  {
      EVP_MD_CTX *ctx;
      unsigned int ret;
  
      ctx = BIO_get_data(bp);
  
      if (size < ctx->digest->md_size)
          return 0;
  
      if (EVP_DigestFinal_ex(ctx, (unsigned char *)buf, &ret) <= 0)
          return -1;
  
      return ((int)ret);
  }
  