text: /*
   * Copyright 1995-2018 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 <time.h>
  #include "internal/cryptlib.h"
  #include <openssl/opensslconf.h>
  #include "internal/rand_int.h"
  #include <openssl/engine.h>
  #include "internal/thread_once.h"
  #include "rand_lcl.h"
  #ifdef OPENSSL_SYS_UNIX
  # include <sys/types.h>
  # include <unistd.h>
  # include <sys/time.h>
  #endif
  #include "e_os.h"
  
  /* Macro to convert two thirty two bit values into a sixty four bit one */
  #define TWO32TO64(a, b) ((((uint64_t)(a)) << 32) + (b))
  
  /*
   * Check for the existence and support of POSIX timers.  The standard
   * says that the _POSIX_TIMERS macro will have a positive value if they
   * are available.
   *
   * However, we want an additional constraint: that the timer support does
   * not require an extra library dependency.  Early versions of glibc
   * require -lrt to be specified on the link line to access the timers,
   * so this needs to be checked for.
   *
   * It is worse because some libraries define __GLIBC__ but don't
   * support the version testing macro (e.g. uClibc).  This means
   * an extra check is needed.
   *
   * The final condition is:
   *      "have posix timers and either not glibc or glibc without -lrt"
   *
   * The nested #if sequences are required to avoid using a parameterised
   * macro that might be undefined.
   */
  #undef OSSL_POSIX_TIMER_OKAY
  #if defined(_POSIX_TIMERS) && _POSIX_TIMERS > 0
  # if defined(__GLIBC__)
  #  if defined(__GLIBC_PREREQ)
  #   if __GLIBC_PREREQ(2, 17)
  #    define OSSL_POSIX_TIMER_OKAY
  #   endif
  #  endif
  # else
  #  define OSSL_POSIX_TIMER_OKAY
  # endif
  #endif
  
  #ifndef OPENSSL_NO_ENGINE
  /* non-NULL if default_RAND_meth is ENGINE-provided */
  static ENGINE *funct_ref;
  static CRYPTO_RWLOCK *rand_engine_lock;
  #endif
  static CRYPTO_RWLOCK *rand_meth_lock;
  static const RAND_METHOD *default_RAND_meth;
  static CRYPTO_ONCE rand_init = CRYPTO_ONCE_STATIC_INIT;
  
  int rand_fork_count;
  
  #ifdef OPENSSL_RAND_SEED_RDTSC
  /*
   * IMPORTANT NOTE:  It is not currently possible to use this code
   * because we are not sure about the amount of randomness it provides.
   * Some SP900 tests have been run, but there is internal skepticism.
   * So for now this code is not used.
   */
  # error "RDTSC enabled?  Should not be possible!"
  
  /*
   * Acquire entropy from high-speed clock
   *
   * Since we get some randomness from the low-order bits of the
   * high-speed clock, it can help.
   *
   * Returns the total entropy count, if it exceeds the requested
   * entropy count. Otherwise, returns an entropy count of 0.
   */
  size_t rand_acquire_entropy_from_tsc(RAND_POOL *pool)
  {
      unsigned char c;
      int i;
  
      if ((OPENSSL_ia32cap_P[0] & (1 << 4)) != 0) {
          for (i = 0; i < TSC_READ_COUNT; i++) {
              c = (unsigned char)(OPENSSL_rdtsc() & 0xFF);
              rand_pool_add(pool, &c, 1, 4);
          }
      }
      return rand_pool_entropy_available(pool);
  }
  #endif
  
  #ifdef OPENSSL_RAND_SEED_RDCPU
  size_t OPENSSL_ia32_rdseed_bytes(unsigned char *buf, size_t len);
  size_t OPENSSL_ia32_rdrand_bytes(unsigned char *buf, size_t len);
  
  extern unsigned int OPENSSL_ia32cap_P[];
  
  /*
   * Acquire entropy using Intel-specific cpu instructions
   *
   * Uses the RDSEED instruction if available, otherwise uses
   * RDRAND if available.
   *
   * For the differences between RDSEED and RDRAND, and why RDSEED
   * is the preferred choice, see https://goo.gl/oK3KcN
   *
   * Returns the total entropy count, if it exceeds the requested
   * entropy count. Otherwise, returns an entropy count of 0.
   */
  size_t rand_acquire_entropy_from_cpu(RAND_POOL *pool)
  {
      size_t bytes_needed;
      unsigned char *buffer;
  
      bytes_needed = rand_pool_bytes_needed(pool, 8 /*entropy_per_byte*/);
      if (bytes_needed > 0) {
          buffer = rand_pool_add_begin(pool, bytes_needed);
  
          if (buffer != NULL) {
              /* Whichever comes first, use RDSEED, RDRAND or nothing */
              if ((OPENSSL_ia32cap_P[2] & (1 << 18)) != 0) {
                  if (OPENSSL_ia32_rdseed_bytes(buffer, bytes_needed)
                      == bytes_needed) {
                      rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
                  }
              } else if ((OPENSSL_ia32cap_P[1] & (1 << (62 - 32))) != 0) {
                  if (OPENSSL_ia32_rdrand_bytes(buffer, bytes_needed)
                      == bytes_needed) {
                      rand_pool_add_end(pool, bytes_needed, 8 * bytes_needed);
                  }
              } else {
                  rand_pool_add_end(pool, 0, 0);
              }
          }
      }
  
      return rand_pool_entropy_available(pool);
  }
  #endif
  
  
  /*
   * Implements the get_entropy() callback (see RAND_DRBG_set_callbacks())
   *
   * If the DRBG has a parent, then the required amount of entropy input
   * is fetched using the parent's RAND_DRBG_generate().
   *
   * Otherwise, the entropy is polled from the system entropy sources
   * using rand_pool_acquire_entropy().
   *
   * If a random pool has been added to the DRBG using RAND_add(), then
   * its entropy will be used up first.
   */
  size_t rand_drbg_get_entropy(RAND_DRBG *drbg,
                               unsigned char **pout,
                               int entropy, size_t min_len, size_t max_len,
                               int prediction_resistance)
  {
      size_t ret = 0;
      size_t entropy_available = 0;
      RAND_POOL *pool;
  
      if (drbg->parent && drbg->strength > drbg->parent->strength) {
          /*
           * We currently don't support the algorithm from NIST SP 800-90C
           * 10.1.2 to use a weaker DRBG as source
           */
          RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY, RAND_R_PARENT_STRENGTH_TOO_WEAK);
          return 0;
      }
  
      pool = rand_pool_new(entropy, min_len, max_len);
      if (pool == NULL)
          return 0;
  
      if (drbg->pool) {
          rand_pool_add(pool,
                        rand_pool_buffer(drbg->pool),
                        rand_pool_length(drbg->pool),
                        rand_pool_entropy(drbg->pool));
          rand_pool_free(drbg->pool);
          drbg->pool = NULL;
      }
  
      if (drbg->parent) {
          size_t bytes_needed = rand_pool_bytes_needed(pool, 8);
          unsigned char *buffer = rand_pool_add_begin(pool, bytes_needed);
  
          if (buffer != NULL) {
              size_t bytes = 0;
  
              /*
               * Get random from parent, include our state as additional input.
               * Our lock is already held, but we need to lock our parent before
               * generating bits from it. (Note: taking the lock will be a no-op
               * if locking if drbg->parent->lock == NULL.)
               */
              rand_drbg_lock(drbg->parent);
              if (RAND_DRBG_generate(drbg->parent,
                                     buffer, bytes_needed,
                                     prediction_resistance,
                                     (unsigned char *)drbg, sizeof(*drbg)) != 0)
                  bytes = bytes_needed;
              rand_drbg_unlock(drbg->parent);
  
              rand_pool_add_end(pool, bytes, 8 * bytes);
              entropy_available = rand_pool_entropy_available(pool);
          }
  
      } else {
          if (prediction_resistance) {
              /*
               * We don't have any entropy sources that comply with the NIST
               * standard to provide prediction resistance (see NIST SP 800-90C,
               * Section 5.4).
               */
              RANDerr(RAND_F_RAND_DRBG_GET_ENTROPY,
                      RAND_R_PREDICTION_RESISTANCE_NOT_SUPPORTED);
              return 0;
          }
  
          /* Get entropy by polling system entropy sources. */
          entropy_available = rand_pool_acquire_entropy(pool);
      }
  
      if (entropy_available > 0) {
          ret   = rand_pool_length(pool);
          *pout = rand_pool_detach(pool);
      }
  
      rand_pool_free(pool);
      return ret;
  }
  
  /*
   * Find a suitable source of time.  Start with the highest resolution source
   * and work down to the slower ones.  This is added as additional data and
   * isn't counted as randomness, so any result is acceptable.
   *
   * Returns 0 when we weren't able to find any time source
   */
  static uint64_t get_timer_bits(void)
  {
      uint64_t res = OPENSSL_rdtsc();
  
      if (res != 0)
          return res;
  #if defined(_WIN32)
      {
          LARGE_INTEGER t;
          FILETIME ft;
  
          if (QueryPerformanceCounter(&t) != 0)
              return t.QuadPart;
          GetSystemTimeAsFileTime(&ft);
          return TWO32TO64(ft.dwHighDateTime, ft.dwLowDateTime);
      }
  #elif defined(__sun) || defined(__hpux)
      return gethrtime();
  #elif defined(_AIX)
      {
          timebasestruct_t t;
  
          read_wall_time(&t, TIMEBASE_SZ);
          return TWO32TO64(t.tb_high, t.tb_low);
      }
  #else
  
  # if defined(OSSL_POSIX_TIMER_OKAY)
      {
          struct timespec ts;
          clockid_t cid;
  
  #  ifdef CLOCK_BOOTTIME
          cid = CLOCK_BOOTTIME;
  #  elif defined(_POSIX_MONOTONIC_CLOCK)
          cid = CLOCK_MONOTONIC;
  #  else
          cid = CLOCK_REALTIME;
  #  endif
  
          if (clock_gettime(cid, &ts) == 0)
              return TWO32TO64(ts.tv_sec, ts.tv_nsec);
      }
  # endif
  # if defined(__unix__) \
       || (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 200112L)
      {
          struct timeval tv;
  
          if (gettimeofday(&tv, NULL) == 0)
              return TWO32TO64(tv.tv_sec, tv.tv_usec);
      }
  # endif
      {
          time_t t = time(NULL);
          if (t == (time_t)-1)
              return 0;
          return t;
      }
  #endif
  }
  
  /*
   * Generate additional data that can be used for the drbg. The data does
   * not need to contain entropy, but it's useful if it contains at least
   * some bits that are unpredictable.
   *
   * Returns 0 on failure.
   *
   * On success it allocates a buffer at |*pout| and returns the length of
   * the data. The buffer should get freed using OPENSSL_secure_clear_free().
   */
  size_t rand_drbg_get_additional_data(unsigned char **pout, size_t max_len)
  {
      RAND_POOL *pool;
      CRYPTO_THREAD_ID thread_id;
      size_t len;
  #ifdef OPENSSL_SYS_UNIX
      pid_t pid;
  #elif defined(OPENSSL_SYS_WIN32)
      DWORD pid;
  #endif
      uint64_t tbits;
  
      pool = rand_pool_new(0, 0, max_len);
      if (pool == NULL)
          return 0;
  
  #ifdef OPENSSL_SYS_UNIX
      pid = getpid();
      rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
  #elif defined(OPENSSL_SYS_WIN32)
      pid = GetCurrentProcessId();
      rand_pool_add(pool, (unsigned char *)&pid, sizeof(pid), 0);
  #endif
  
      thread_id = CRYPTO_THREAD_get_current_id();
      if (thread_id != 0)
          rand_pool_add(pool, (unsigned char *)&thread_id, sizeof(thread_id), 0);
  
      tbits = get_timer_bits();
      if (tbits != 0)
          rand_pool_add(pool, (unsigned char *)&tbits, sizeof(tbits), 0);
  
      /* TODO: Use RDSEED? */
  
      len = rand_pool_length(pool);
      if (len != 0)
          *pout = rand_pool_detach(pool);
      rand_pool_free(pool);
  
      return len;
  }
  
  /*
   * Implements the cleanup_entropy() callback (see RAND_DRBG_set_callbacks())
   *
   */
  void rand_drbg_cleanup_entropy(RAND_DRBG *drbg,
                                 unsigned char *out, size_t outlen)
  {
      OPENSSL_secure_clear_free(out, outlen);
  }
  
  void rand_fork()
  {
      rand_fork_count++;
  }
  
  DEFINE_RUN_ONCE_STATIC(do_rand_init)
  {
      int ret = 1;
  
  #ifndef OPENSSL_NO_ENGINE
      rand_engine_lock = CRYPTO_THREAD_lock_new();
      ret &= rand_engine_lock != NULL;
  #endif
      rand_meth_lock = CRYPTO_THREAD_lock_new();
      ret &= rand_meth_lock != NULL;
  
      return ret;
  }
  
  void rand_cleanup_int(void)
  {
      const RAND_METHOD *meth = default_RAND_meth;
  
      if (meth != NULL && meth->cleanup != NULL)
          meth->cleanup();
      RAND_set_rand_method(NULL);
  #ifndef OPENSSL_NO_ENGINE
      CRYPTO_THREAD_lock_free(rand_engine_lock);
  #endif
      CRYPTO_THREAD_lock_free(rand_meth_lock);
  }
  
  /*
   * RAND_poll() reseeds the default RNG using random input
   *
   * The random input is obtained from polling various entropy
   * sources which depend on the operating system and are
   * configurable via the --with-rand-seed configure option.
   */
  int RAND_poll(void)
  {
      int ret = 0;
  
      RAND_POOL *pool = NULL;
  
      const RAND_METHOD *meth = RAND_get_rand_method();
  
      if (meth == RAND_OpenSSL()) {
          /* fill random pool and seed the master DRBG */
          RAND_DRBG *drbg = RAND_DRBG_get0_master();
  
          if (drbg == NULL)
              return 0;
  
          rand_drbg_lock(drbg);
          ret = rand_drbg_restart(drbg, NULL, 0, 0);
          rand_drbg_unlock(drbg);
  
          return ret;
  
      } else {
          /* fill random pool and seed the current legacy RNG */
          pool = rand_pool_new(RAND_DRBG_STRENGTH,
                               RAND_DRBG_STRENGTH / 8,
                               DRBG_MINMAX_FACTOR * (RAND_DRBG_STRENGTH / 8));
          if (pool == NULL)
              return 0;
  
          if (rand_pool_acquire_entropy(pool) == 0)
              goto err;
  
          if (meth->add == NULL
              || meth->add(rand_pool_buffer(pool),
                           rand_pool_length(pool),
                           (rand_pool_entropy(pool) / 8.0)) == 0)
              goto err;
  
          ret = 1;
      }
  
  err:
      rand_pool_free(pool);
      return ret;
  }
  
  /*
   * Allocate memory and initialize a new random pool
   */
  
  RAND_POOL *rand_pool_new(int entropy, size_t min_len, size_t max_len)
  {
      RAND_POOL *pool = OPENSSL_zalloc(sizeof(*pool));
  
      if (pool == NULL) {
          RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
          goto err;
      }
  
      pool->min_len = min_len;
      pool->max_len = max_len;
  
      pool->buffer = OPENSSL_secure_zalloc(pool->max_len);
      if (pool->buffer == NULL) {
          RANDerr(RAND_F_RAND_POOL_NEW, ERR_R_MALLOC_FAILURE);
          goto err;
      }
  
      pool->requested_entropy = entropy;
  
      return pool;
  
  err:
      OPENSSL_free(pool);
      return NULL;
  }
  
  /*
   * Free |pool|, securely erasing its buffer.
   */
  void rand_pool_free(RAND_POOL *pool)
  {
      if (pool == NULL)
          return;
  
      OPENSSL_secure_clear_free(pool->buffer, pool->max_len);
      OPENSSL_free(pool);
  }
  
  /*
   * Return the |pool|'s buffer to the caller (readonly).
   */
  const unsigned char *rand_pool_buffer(RAND_POOL *pool)
  {
      return pool->buffer;
  }
  
  /*
   * Return the |pool|'s entropy to the caller.
   */
  size_t rand_pool_entropy(RAND_POOL *pool)
  {
      return pool->entropy;
  }
  
  /*
   * Return the |pool|'s buffer length to the caller.
   */
  size_t rand_pool_length(RAND_POOL *pool)
  {
      return pool->len;
  }
  
  /*
   * Detach the |pool| buffer and return it to the caller.
   * It's the responsibility of the caller to free the buffer
   * using OPENSSL_secure_clear_free().
   */
  unsigned char *rand_pool_detach(RAND_POOL *pool)
  {
      unsigned char *ret = pool->buffer;
      pool->buffer = NULL;
      return ret;
  }
  
  
  /*
   * If every byte of the input contains |entropy_per_bytes| bits of entropy,
   * how many bytes does one need to obtain at least |bits| bits of entropy?
   */
  #define ENTROPY_TO_BYTES(bits, entropy_per_bytes) \
      (((bits) + ((entropy_per_bytes) - 1))/(entropy_per_bytes))
  
  
  /*
   * Checks whether the |pool|'s entropy is available to the caller.
   * This is the case when entropy count and buffer length are high enough.
   * Returns
   *
   *  |entropy|  if the entropy count and buffer size is large enough
   *      0      otherwise
   */
  size_t rand_pool_entropy_available(RAND_POOL *pool)
  {
      if (pool->entropy < pool->requested_entropy)
          return 0;
  
      if (pool->len < pool->min_len)
          return 0;
  
      return pool->entropy;
  }
  
  /*
   * Returns the (remaining) amount of entropy needed to fill
   * the random pool.
   */
  
  size_t rand_pool_entropy_needed(RAND_POOL *pool)
  {
      if (pool->entropy < pool->requested_entropy)
          return pool->requested_entropy - pool->entropy;
  
      return 0;
  }
  
  /*
   * Returns the number of bytes needed to fill the pool, assuming
   * the input has 'entropy_per_byte' entropy bits per byte.
   * In case of an error, 0 is returned.
   */
  
  size_t rand_pool_bytes_needed(RAND_POOL *pool, unsigned int entropy_per_byte)
  {
      size_t bytes_needed;
      size_t entropy_needed = rand_pool_entropy_needed(pool);
  
      if (entropy_per_byte < 1 || entropy_per_byte > 8) {
          RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_ARGUMENT_OUT_OF_RANGE);
          return 0;
      }
  
      bytes_needed = ENTROPY_TO_BYTES(entropy_needed, entropy_per_byte);
  
      if (bytes_needed > pool->max_len - pool->len) {
          /* not enough space left */
          RANDerr(RAND_F_RAND_POOL_BYTES_NEEDED, RAND_R_RANDOM_POOL_OVERFLOW);
          return 0;
      }
  
      if (pool->len < pool->min_len &&
          bytes_needed < pool->min_len - pool->len)
          /* to meet the min_len requirement */
          bytes_needed = pool->min_len - pool->len;
  
      return bytes_needed;
  }
  
  /* Returns the remaining number of bytes available */
  size_t rand_pool_bytes_remaining(RAND_POOL *pool)
  {
      return pool->max_len - pool->len;
  }
  
  /*
   * Add random bytes to the random pool.
   *
   * It is expected that the |buffer| contains |len| bytes of
   * random input which contains at least |entropy| bits of
   * randomness.
   *
   * Returns 1 if the added amount is adequate, otherwise 0
   */
  int rand_pool_add(RAND_POOL *pool,
                    const unsigned char *buffer, size_t len, size_t entropy)
  {
      if (len > pool->max_len - pool->len) {
          RANDerr(RAND_F_RAND_POOL_ADD, RAND_R_ENTROPY_INPUT_TOO_LONG);
          return 0;
      }
  
      if (len > 0) {
          memcpy(pool->buffer + pool->len, buffer, len);
          pool->len += len;
          pool->entropy += entropy;
      }
  
      return 1;
  }
  
  /*
   * Start to add random bytes to the random pool in-place.
   *
   * Reserves the next |len| bytes for adding random bytes in-place
   * and returns a pointer to the buffer.
   * The caller is allowed to copy up to |len| bytes into the buffer.
   * If |len| == 0 this is considered a no-op and a NULL pointer
   * is returned without producing an error message.
   *
   * After updating the buffer, rand_pool_add_end() needs to be called
   * to finish the udpate operation (see next comment).
   */
  unsigned char *rand_pool_add_begin(RAND_POOL *pool, size_t len)
  {
      if (len == 0)
          return NULL;
  
      if (len > pool->max_len - pool->len) {
          RANDerr(RAND_F_RAND_POOL_ADD_BEGIN, RAND_R_RANDOM_POOL_OVERFLOW);
          return NULL;
      }
  
      return pool->buffer + pool->len;
  }
  
  /*
   * Finish to add random bytes to the random pool in-place.
   *
   * Finishes an in-place update of the random pool started by
   * rand_pool_add_begin() (see previous comment).
   * It is expected that |len| bytes of random input have been added
   * to the buffer which contain at least |entropy| bits of randomness.
   * It is allowed to add less bytes than originally reserved.
   */
  int rand_pool_add_end(RAND_POOL *pool, size_t len, size_t entropy)
  {
      if (len > pool->max_len - pool->len) {
          RANDerr(RAND_F_RAND_POOL_ADD_END, RAND_R_RANDOM_POOL_OVERFLOW);
          return 0;
      }
  
      if (len > 0) {
          pool->len += len;
          pool->entropy += entropy;
      }
  
      return 1;
  }
  
  int RAND_set_rand_method(const RAND_METHOD *meth)
  {
      if (!RUN_ONCE(&rand_init, do_rand_init))
          return 0;
  
      CRYPTO_THREAD_write_lock(rand_meth_lock);
  #ifndef OPENSSL_NO_ENGINE
      ENGINE_finish(funct_ref);
      funct_ref = NULL;
  #endif
      default_RAND_meth = meth;
      CRYPTO_THREAD_unlock(rand_meth_lock);
      return 1;
  }
  
  const RAND_METHOD *RAND_get_rand_method(void)
  {
      const RAND_METHOD *tmp_meth = NULL;
  
      if (!RUN_ONCE(&rand_init, do_rand_init))
          return NULL;
  
      CRYPTO_THREAD_write_lock(rand_meth_lock);
      if (default_RAND_meth == NULL) {
  #ifndef OPENSSL_NO_ENGINE
          ENGINE *e;
  
          /* If we have an engine that can do RAND, use it. */
          if ((e = ENGINE_get_default_RAND()) != NULL
                  && (tmp_meth = ENGINE_get_RAND(e)) != NULL) {
              funct_ref = e;
              default_RAND_meth = tmp_meth;
          } else {
              ENGINE_finish(e);
              default_RAND_meth = &rand_meth;
          }
  #else
          default_RAND_meth = &rand_meth;
  #endif
      }
      tmp_meth = default_RAND_meth;
      CRYPTO_THREAD_unlock(rand_meth_lock);
      return tmp_meth;
  }
  
  #ifndef OPENSSL_NO_ENGINE
  int RAND_set_rand_engine(ENGINE *engine)
  {
      const RAND_METHOD *tmp_meth = NULL;
  
      if (!RUN_ONCE(&rand_init, do_rand_init))
          return 0;
  
      if (engine != NULL) {
          if (!ENGINE_init(engine))
              return 0;
          tmp_meth = ENGINE_get_RAND(engine);
          if (tmp_meth == NULL) {
              ENGINE_finish(engine);
              return 0;
          }
      }
      CRYPTO_THREAD_write_lock(rand_engine_lock);
      /* This function releases any prior ENGINE so call it first */
      RAND_set_rand_method(tmp_meth);
      funct_ref = engine;
      CRYPTO_THREAD_unlock(rand_engine_lock);
      return 1;
  }
  #endif
  
  void RAND_seed(const void *buf, int num)
  {
      const RAND_METHOD *meth = RAND_get_rand_method();
  
      if (meth->seed != NULL)
          meth->seed(buf, num);
  }
  
  void RAND_add(const void *buf, int num, double randomness)
  {
      const RAND_METHOD *meth = RAND_get_rand_method();
  
      if (meth->add != NULL)
          meth->add(buf, num, randomness);
  }
  
  /*
   * This function is not part of RAND_METHOD, so if we're not using
   * the default method, then just call RAND_bytes().  Otherwise make
   * sure we're instantiated and use the private DRBG.
   */
  int RAND_priv_bytes(unsigned char *buf, int num)
  {
      const RAND_METHOD *meth = RAND_get_rand_method();
      RAND_DRBG *drbg;
      int ret;
  
      if (meth != RAND_OpenSSL())
          return RAND_bytes(buf, num);
  
      drbg = RAND_DRBG_get0_private();
      if (drbg == NULL)
          return 0;
  
      ret = RAND_DRBG_bytes(drbg, buf, num);
      return ret;
  }
  
  int RAND_bytes(unsigned char *buf, int num)
  {
      const RAND_METHOD *meth = RAND_get_rand_method();
  
      if (meth->bytes != NULL)
          return meth->bytes(buf, num);
      RANDerr(RAND_F_RAND_BYTES, RAND_R_FUNC_NOT_IMPLEMENTED);
      return -1;
  }
  
  #if OPENSSL_API_COMPAT < 0x10100000L
  int RAND_pseudo_bytes(unsigned char *buf, int num)
  {
      const RAND_METHOD *meth = RAND_get_rand_method();
  
      if (meth->pseudorand != NULL)
          return meth->pseudorand(buf, num);
      return -1;
  }
  #endif
  
  int RAND_status(void)
  {
      const RAND_METHOD *meth = RAND_get_rand_method();
  
      if (meth->status != NULL)
          return meth->status();
      return 0;
  }
  