text: /*-
   * Copyright (c) 2015-2018 Mark R V Murray
   * All rights reserved.
   *
   * 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 above copyright
   *    notice, this list of conditions and the following disclaimer
   *    in this position and unchanged.
   * 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.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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.
   *
   */
  
  /*-
   * This is a skeleton for folks who wish to build a loadable module
   * containing an alternative entropy-processing algorithm for random(4).
   *
   * The functions below should be completed with the appropriate code,
   * and the nearby fortuna.c may be consulted for examples of working code.
   *
   * The author is willing to provide reasonable help to those wishing to
   * write such a module for themselves. Please use the markm@ FreeBSD
   * email address, and ensure that you are developing this on a suitably
   * supported branch (This is currently 12-CURRENT, and may be no
   * older than 12-STABLE in the future).
   */
  
  #include <sys/cdefs.h>
  __FBSDID("$FreeBSD$");
  
  #include <sys/limits.h>
  
  #ifdef _KERNEL
  #include <sys/param.h>
  #include <sys/kernel.h>
  #include <sys/lock.h>
  #include <sys/malloc.h>
  #include <sys/mutex.h>
  #include <sys/random.h>
  #include <sys/sysctl.h>
  #include <sys/systm.h>
  
  #include <machine/cpu.h>
  
  #include <crypto/rijndael/rijndael-api-fst.h>
  #include <crypto/sha2/sha256.h>
  
  #include <dev/random/hash.h>
  #include <dev/random/randomdev.h>
  #include <dev/random/random_harvestq.h>
  #include <dev/random/uint128.h>
  #include <dev/random/other_algorithm.h>
  #else /* !_KERNEL */
  #include <inttypes.h>
  #include <stdbool.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <threads.h>
  
  #include "unit_test.h"
  
  #include <crypto/rijndael/rijndael-api-fst.h>
  #include <crypto/sha2/sha256.h>
  
  #include <dev/random/hash.h>
  #include <dev/random/randomdev.h>
  #include <dev/random/uint128.h>
  #include <dev/random/other_algorithm.h>
  #endif /* _KERNEL */
  
  static void random_other_pre_read(void);
  static void random_other_read(uint8_t *, size_t);
  static bool random_other_seeded(void);
  static void random_other_process_event(struct harvest_event *);
  
  /*
   * RANDOM_OTHER_NPOOLS is used when reading hardware random
   * number sources to ensure that each pool gets one read sample
   * per loop iteration. Fortuna has 32 (0-31).
   */
  #define RANDOM_OTHER_NPOOLS 1
  
  #ifdef RANDOM_LOADABLE
  static
  #endif
  const struct random_algorithm random_alg_context = {
  	.ra_ident = "other",
  	.ra_pre_read = random_other_pre_read,
  	.ra_read = random_other_read,
  	.ra_seeded = random_other_seeded,
  	.ra_event_processor = random_other_process_event,
  	.ra_poolcount = RANDOM_OTHER_NPOOLS,
  };
  
  /* Use a mutex to protect your reseed variables? */
  static mtx_t other_mtx;
  
  /*
   * Do algorithm-specific initialisation here.
   */
  static void
  random_other_init_alg(void *unused __unused)
  {
  
  #ifdef RANDOM_LOADABLE
  	p_random_alg_context = &random_alg_context;
  #endif
  
  	RANDOM_RESEED_INIT_LOCK();
  }
  SYSINIT(random_alg, SI_SUB_RANDOM, SI_ORDER_SECOND, random_other_init_alg,
      NULL);
  
  /*
   * void random_other_pre_read(void)
   *
   * Do any pre-read preparation you need to. This will be called
   * before >=1 calls to random_other_read() corresponding to one
   * read(2).
   *
   * This routine will be called periodically while the generator is
   * still blocked and a read is being attempted, giving you an
   * opportunity to unblock.
   */
  static void
  random_other_pre_read(void)
  {
  
  	RANDOM_RESEED_LOCK();
  	/*
  	 * Do pre-read housekeeping work here!
  	 * You may use this as a chance to unblock the generator.
  	 */
  	RANDOM_RESEED_UNLOCK();
  }
  
  /*
   * void random_other_read(uint8_t *buf, size_t count)
   *
   * Generate <count> bytes of output into <*buf>.
   * You may NOT use the fact that <count> will be a multiple of
   * RANDOM_BLOCKSIZE for optimization purposes.
   *
   * This function will always be called with your generator
   * unblocked and ready. If you are not ready to generate
   * output here, then feel free to KASSERT() or panic().
   */
  static void
  random_other_read(uint8_t *buf, size_t count)
  {
  
  	RANDOM_RESEED_LOCK();
  	/*
  	 * Do random-number generation work here!
  	 */
  	RANDOM_RESEED_UNLOCK();
  }
  
  /*
   * bool random_other_seeded(void)
   *
   * Return true if your generator is ready to generate
   * output, and false otherwise.
   */
  static bool
  random_other_seeded(void)
  {
  	bool seeded = false;
  
  	/*
  	 * Find out if your generator is seeded here!
  	 */
  	return (seeded);
  }
  
  /*
   * void random_other_process_event(struct harvest_event *event)
   *
   * Process one stochastic event <*event> into your entropy
   * processor.
   *
   * The structure of the event may change, so it is easier to
   * just grab the whole thing into your accumulation system.
   * You may pick-and-choose bits, but please don't complain
   * when/if these change.
   */
  static void
  random_other_process_event(struct harvest_event *event)
  {
  
  	RANDOM_RESEED_LOCK();
  	/*
  	 * Do entropy accumulation work here!
  	 * You may use this as a chance to unblock the generator.
  	 */
  	RANDOM_RESEED_UNLOCK();
  }
  