text: /*
   * Copyright 2011-2017 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 <string.h>
  #include <openssl/crypto.h>
  #include <openssl/err.h>
  #include <openssl/rand.h>
  #include "rand_lcl.h"
  #include "internal/thread_once.h"
  #include "internal/rand_int.h"
  
  static RAND_DRBG rand_drbg; /* The default global DRBG. */
  static RAND_DRBG priv_drbg; /* The global private-key DRBG. */
  
  /*
   * Support framework for NIST SP 800-90A DRBG, AES-CTR mode.
   * The RAND_DRBG is OpenSSL's pointer to an instance of the DRBG.
   *
   * The OpenSSL model is to have new and free functions, and that new
   * does all initialization.  That is not the NIST model, which has
   * instantiation and un-instantiate, and re-use within a new/free
   * lifecycle.  (No doubt this comes from the desire to support hardware
   * DRBG, where allocation of resources on something like an HSM is
   * a much bigger deal than just re-setting an allocated resource.)
   */
  
  static CRYPTO_ONCE rand_init_drbg = CRYPTO_ONCE_STATIC_INIT;
  
  /*
   * Set/initialize |drbg| to be of type |nid|, with optional |flags|.
   * Return -2 if the type is not supported, 1 on success and -1 on
   * failure.
   */
  int RAND_DRBG_set(RAND_DRBG *drbg, int nid, unsigned int flags)
  {
      int ret = 1;
  
      drbg->state = DRBG_UNINITIALISED;
      drbg->flags = flags;
      drbg->nid = nid;
  
      switch (nid) {
      default:
          RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_UNSUPPORTED_DRBG_TYPE);
          return -2;
      case 0:
          /* Uninitialized; that's okay. */
          return 1;
      case NID_aes_128_ctr:
      case NID_aes_192_ctr:
      case NID_aes_256_ctr:
          ret = ctr_init(drbg);
          break;
      }
  
      if (ret < 0)
          RANDerr(RAND_F_RAND_DRBG_SET, RAND_R_ERROR_INITIALISING_DRBG);
      return ret;
  }
  
  /*
   * Allocate memory and initialize a new DRBG.  The |parent|, if not
   * NULL, will be used to auto-seed this RAND_DRBG as needed.
   */
  RAND_DRBG *RAND_DRBG_new(int type, unsigned int flags, RAND_DRBG *parent)
  {
      RAND_DRBG *drbg = OPENSSL_zalloc(sizeof(*drbg));
  
      if (drbg == NULL) {
          RANDerr(RAND_F_RAND_DRBG_NEW, ERR_R_MALLOC_FAILURE);
          goto err;
      }
      drbg->size = RANDOMNESS_NEEDED;
      drbg->fork_count = rand_fork_count;
      drbg->parent = parent;
      if (RAND_DRBG_set(drbg, type, flags) < 0)
          goto err;
  
      if (parent != NULL) {
          if (!RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_parent,
                                       drbg_release_entropy,
                                       NULL, NULL))
              goto err;
      }
  
      return drbg;
  
  err:
      OPENSSL_free(drbg);
      return NULL;
  }
  
  /*
   * Uninstantiate |drbg| and free all memory.
   */
  void RAND_DRBG_free(RAND_DRBG *drbg)
  {
      /* The global DRBG is free'd by rand_cleanup_drbg_int() */
      if (drbg == NULL || drbg == &rand_drbg)
          return;
  
      ctr_uninstantiate(drbg);
      CRYPTO_free_ex_data(CRYPTO_EX_INDEX_DRBG, drbg, &drbg->ex_data);
      OPENSSL_clear_free(drbg, sizeof(*drbg));
  }
  
  /*
   * Instantiate |drbg|, after it has been initialized.  Use |pers| and
   * |perslen| as prediction-resistance input.
   */
  int RAND_DRBG_instantiate(RAND_DRBG *drbg,
                            const unsigned char *pers, size_t perslen)
  {
      unsigned char *nonce = NULL, *entropy = NULL;
      size_t noncelen = 0, entropylen = 0;
  
      if (perslen > drbg->max_perslen) {
          RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
                  RAND_R_PERSONALISATION_STRING_TOO_LONG);
          goto end;
      }
      if (drbg->state != DRBG_UNINITIALISED) {
          RANDerr(RAND_F_RAND_DRBG_INSTANTIATE,
                  drbg->state == DRBG_ERROR ? RAND_R_IN_ERROR_STATE
                                            : RAND_R_ALREADY_INSTANTIATED);
          goto end;
      }
  
      drbg->state = DRBG_ERROR;
      if (drbg->get_entropy != NULL)
          entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
                                     drbg->min_entropylen, drbg->max_entropylen);
      if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) {
          RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_ENTROPY);
          goto end;
      }
  
      if (drbg->max_noncelen > 0 && drbg->get_nonce != NULL) {
          noncelen = drbg->get_nonce(drbg, &nonce, drbg->strength / 2,
                                     drbg->min_noncelen, drbg->max_noncelen);
          if (noncelen < drbg->min_noncelen || noncelen > drbg->max_noncelen) {
              RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_RETRIEVING_NONCE);
              goto end;
          }
      }
  
      if (!ctr_instantiate(drbg, entropy, entropylen,
                           nonce, noncelen, pers, perslen)) {
          RANDerr(RAND_F_RAND_DRBG_INSTANTIATE, RAND_R_ERROR_INSTANTIATING_DRBG);
          goto end;
      }
  
      drbg->state = DRBG_READY;
      drbg->reseed_counter = 1;
  
  end:
      if (entropy != NULL && drbg->cleanup_entropy != NULL)
          drbg->cleanup_entropy(drbg, entropy, entropylen);
      if (nonce != NULL && drbg->cleanup_nonce!= NULL )
          drbg->cleanup_nonce(drbg, nonce, noncelen);
      if (drbg->state == DRBG_READY)
          return 1;
      return 0;
  }
  
  /*
   * Uninstantiate |drbg|. Must be instantiated before it can be used.
   */
  int RAND_DRBG_uninstantiate(RAND_DRBG *drbg)
  {
      int ret = ctr_uninstantiate(drbg);
  
      OPENSSL_cleanse(&drbg->ctr, sizeof(drbg->ctr));
      drbg->state = DRBG_UNINITIALISED;
      return ret;
  }
  
  /*
   * Mix in the specified data to reseed |drbg|.
   */
  int RAND_DRBG_reseed(RAND_DRBG *drbg,
                       const unsigned char *adin, size_t adinlen)
  {
      unsigned char *entropy = NULL;
      size_t entropylen = 0;
  
      if (drbg->state == DRBG_ERROR) {
          RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_IN_ERROR_STATE);
          return 0;
      }
      if (drbg->state == DRBG_UNINITIALISED) {
          RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_NOT_INSTANTIATED);
          return 0;
      }
  
      if (adin == NULL)
          adinlen = 0;
      else if (adinlen > drbg->max_adinlen) {
          RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
          return 0;
      }
  
      drbg->state = DRBG_ERROR;
      if (drbg->get_entropy != NULL)
          entropylen = drbg->get_entropy(drbg, &entropy, drbg->strength,
                                     drbg->min_entropylen, drbg->max_entropylen);
      if (entropylen < drbg->min_entropylen || entropylen > drbg->max_entropylen) {
          RANDerr(RAND_F_RAND_DRBG_RESEED, RAND_R_ERROR_RETRIEVING_ENTROPY);
          goto end;
      }
  
      if (!ctr_reseed(drbg, entropy, entropylen, adin, adinlen))
          goto end;
      drbg->state = DRBG_READY;
      drbg->reseed_counter = 1;
  
  end:
      if (entropy != NULL && drbg->cleanup_entropy != NULL)
          drbg->cleanup_entropy(drbg, entropy, entropylen);
      if (drbg->state == DRBG_READY)
          return 1;
      return 0;
  }
  
  /*
   * Generate |outlen| bytes into the buffer at |out|.  Reseed if we need
   * to or if |prediction_resistance| is set.  Additional input can be
   * sent in |adin| and |adinlen|.
   */
  int RAND_DRBG_generate(RAND_DRBG *drbg, unsigned char *out, size_t outlen,
                         int prediction_resistance,
                         const unsigned char *adin, size_t adinlen)
  {
      if (drbg->state == DRBG_ERROR) {
          RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_IN_ERROR_STATE);
          return 0;
      }
      if (drbg->state == DRBG_UNINITIALISED) {
          RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_NOT_INSTANTIATED);
          return 0;
      }
      if (outlen > drbg->max_request) {
          RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_REQUEST_TOO_LARGE_FOR_DRBG);
          return 0;
      }
      if (adinlen > drbg->max_adinlen) {
          RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_ADDITIONAL_INPUT_TOO_LONG);
          return 0;
      }
  
      if (drbg->fork_count != rand_fork_count) {
          drbg->fork_count = rand_fork_count;
          drbg->state = DRBG_RESEED;
      }
  
      if (drbg->reseed_counter >= drbg->reseed_interval)
          drbg->state = DRBG_RESEED;
  
      if (drbg->state == DRBG_RESEED || prediction_resistance) {
          if (!RAND_DRBG_reseed(drbg, adin, adinlen)) {
              RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_RESEED_ERROR);
              return 0;
          }
          adin = NULL;
          adinlen = 0;
      }
  
      if (!ctr_generate(drbg, out, outlen, adin, adinlen)) {
          drbg->state = DRBG_ERROR;
          RANDerr(RAND_F_RAND_DRBG_GENERATE, RAND_R_GENERATE_ERROR);
          return 0;
      }
  
      if (drbg->reseed_counter >= drbg->reseed_interval)
          drbg->state = DRBG_RESEED;
      else
          drbg->reseed_counter++;
      return 1;
  }
  
  /*
   * Set the callbacks for entropy and nonce.  We currently don't use
   * the nonce; that's mainly for the KATs
   */
  int RAND_DRBG_set_callbacks(RAND_DRBG *drbg,
                              RAND_DRBG_get_entropy_fn cb_get_entropy,
                              RAND_DRBG_cleanup_entropy_fn cb_cleanup_entropy,
                              RAND_DRBG_get_nonce_fn cb_get_nonce,
                              RAND_DRBG_cleanup_nonce_fn cb_cleanup_nonce)
  {
      if (drbg->state != DRBG_UNINITIALISED)
          return 0;
      drbg->get_entropy = cb_get_entropy;
      drbg->cleanup_entropy = cb_cleanup_entropy;
      drbg->get_nonce = cb_get_nonce;
      drbg->cleanup_nonce = cb_cleanup_nonce;
      return 1;
  }
  
  /*
   * Set the reseed interval.
   */
  int RAND_DRBG_set_reseed_interval(RAND_DRBG *drbg, int interval)
  {
      if (interval < 0 || interval > MAX_RESEED)
          return 0;
      drbg->reseed_interval = interval;
      return 1;
  }
  
  /*
   * Get and set the EXDATA
   */
  int RAND_DRBG_set_ex_data(RAND_DRBG *drbg, int idx, void *arg)
  {
      return CRYPTO_set_ex_data(&drbg->ex_data, idx, arg);
  }
  
  void *RAND_DRBG_get_ex_data(const RAND_DRBG *drbg, int idx)
  {
      return CRYPTO_get_ex_data(&drbg->ex_data, idx);
  }
  
  
  /*
   * The following functions provide a RAND_METHOD that works on the
   * global DRBG.  They lock.
   */
  
  /*
   * Creates a global DRBG with default settings.
   * Returns 1 on success, 0 on failure
   */
  static int setup_drbg(RAND_DRBG *drbg, const char *name)
  {
      int ret = 1;
  
      drbg->lock = CRYPTO_THREAD_glock_new(name);
      ret &= drbg->lock != NULL;
      drbg->size = RANDOMNESS_NEEDED;
      drbg->secure = CRYPTO_secure_malloc_initialized();
      /* If you change these parameters, see RANDOMNESS_NEEDED */
      ret &= RAND_DRBG_set(drbg,
                           NID_aes_128_ctr, RAND_DRBG_FLAG_CTR_USE_DF) == 1;
      ret &= RAND_DRBG_set_callbacks(drbg, drbg_entropy_from_system,
                                     drbg_release_entropy, NULL, NULL) == 1;
      ret &= RAND_DRBG_instantiate(drbg, NULL, 0) == 1;
      return ret;
  }
  
  /*
   * Initialize the global DRBGs on first use.
   * Returns 1 on success, 0 on failure.
   */
  DEFINE_RUN_ONCE_STATIC(do_rand_init_drbg)
  {
      int ret = 1;
  
      ret &= setup_drbg(&rand_drbg, "rand_drbg");
      ret &= setup_drbg(&priv_drbg, "priv_drbg");
  
      return ret;
  }
  
  /* Clean up a DRBG and free it */
  static void free_drbg(RAND_DRBG *drbg)
  {
      CRYPTO_THREAD_lock_free(drbg->lock);
      RAND_DRBG_uninstantiate(drbg);
  }
  
  /* Clean up the global DRBGs before exit */
  void rand_cleanup_drbg_int(void)
  {
      free_drbg(&rand_drbg);
      free_drbg(&priv_drbg);
  }
  
  static int drbg_bytes(unsigned char *out, int count)
  {
      int ret = 0;
      size_t chunk;
      RAND_DRBG *drbg = RAND_DRBG_get0_global();
  
      if (drbg == NULL)
          return 0;
  
      CRYPTO_THREAD_write_lock(drbg->lock);
      if (drbg->state == DRBG_UNINITIALISED)
          goto err;
  
      for ( ; count > 0; count -= chunk, out += chunk) {
          chunk = count;
          if (chunk > drbg->max_request)
              chunk = drbg->max_request;
          ret = RAND_DRBG_generate(drbg, out, chunk, 0, NULL, 0);
          if (!ret)
              goto err;
      }
      ret = 1;
  
  err:
      CRYPTO_THREAD_unlock(drbg->lock);
      return ret;
  }
  
  static int drbg_add(const void *buf, int num, double randomness)
  {
      unsigned char *in = (unsigned char *)buf;
      unsigned char *out, *end;
  
      CRYPTO_THREAD_write_lock(rand_bytes.lock);
      out = &rand_bytes.buff[rand_bytes.curr];
      end = &rand_bytes.buff[rand_bytes.size];
  
      /* Copy whatever fits into the end of the buffer. */
      for ( ; --num >= 0 && out < end; rand_bytes.curr++)
          *out++ = *in++;
  
      /* XOR any the leftover. */
      while (num > 0) {
          for (out = rand_bytes.buff; --num >= 0 && out < end; )
              *out++ ^= *in++;
      }
  
      CRYPTO_THREAD_unlock(rand_bytes.lock);
      return 1;
  }
  
  static int drbg_seed(const void *buf, int num)
  {
      return drbg_add(buf, num, num);
  }
  
  static int drbg_status(void)
  {
      int ret;
      RAND_DRBG *drbg = RAND_DRBG_get0_global();
  
      if (drbg == NULL)
          return 0;
  
      CRYPTO_THREAD_write_lock(drbg->lock);
      ret = drbg->state == DRBG_READY ? 1 : 0;
      CRYPTO_THREAD_unlock(drbg->lock);
      return ret;
  }
  
  /*
   * Get the global public DRBG.
   * Returns pointer to the DRBG on success, NULL on failure.
   */
  RAND_DRBG *RAND_DRBG_get0_global(void)
  {
      if (!RUN_ONCE(&rand_init_drbg, do_rand_init_drbg))
          return NULL;
  
      return &rand_drbg;
  }
  
  /*
   * Get the global private DRBG.
   * Returns pointer to the DRBG on success, NULL on failure.
   */
  RAND_DRBG *RAND_DRBG_get0_priv_global(void)
  {
      if (!RUN_ONCE(&rand_init_drbg, do_rand_init_drbg))
          return NULL;
  
      return &priv_drbg;
  }
  
  RAND_METHOD rand_meth = {
      drbg_seed,
      drbg_bytes,
      NULL,
      drbg_add,
      drbg_bytes,
      drbg_status
  };
  
  RAND_METHOD *RAND_OpenSSL(void)
  {
      return &rand_meth;
  }
  