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+/*
+ * util/random.h - thread safe random generator, which is reasonably secure.
+ * 
+ * Copyright (c) 2007, NLnet Labs. All rights reserved.
+ * 
+ * This software is open source.
+ * 
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 
+ * Redistributions of source code must retain the above copyright notice,
+ * this list of conditions and the following disclaimer.
+ * 
+ * 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.
+ * 
+ * Neither the name of the NLNET LABS nor the names of its contributors may
+ * be used to endorse or promote products derived from this software without
+ * specific prior written permission.
+ * 
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "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 COPYRIGHT
+ * HOLDER 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.
+ */
+
+#ifndef UTIL_RANDOM_H
+#define UTIL_RANDOM_H
+
+/**
+ * \file
+ * Thread safe random functions. Similar to arc4random() with an explicit
+ * initialisation routine.
+ */
+
+/**
+ * random state structure.
+ */
+struct ub_randstate;
+
+/**
+ * Initialize the system randomness.  Obtains entropy from the system
+ * before a chroot or privilege makes it unavailable. 
+ * You do not have to call this, otherwise ub_initstate does so.
+ * @param seed: seed value to create state (if no good entropy is found).
+ */
+void ub_systemseed(unsigned int seed);
+
+/**
+ * Initialize a random generator state for use 
+ * @param seed: seed value to create state contents.
+ *	(ignored for arc4random).
+ * @param from: if not NULL, the seed is taken from this random structure.
+ * 	can be used to seed random states via a parent-random-state that
+ * 	is itself seeded with entropy.
+ * @return new state or NULL alloc failure.
+ */
+struct ub_randstate* ub_initstate(unsigned int seed, 
+	struct ub_randstate* from);
+
+/**
+ * Generate next random number from the state passed along.
+ * Thread safe, so random numbers are repeatable.
+ * @param state: must have been initialised with ub_initstate.
+ * @return: random 31 bit value.
+ */
+long int ub_random(struct ub_randstate* state);
+
+/**
+ * Generate random number between 0 and x-1.  No modulo bias.
+ * @param state: must have been initialised with ub_initstate.
+ * @param x: an upper limit. not (negative or zero). must be smaller than 2**31.
+ * @return: random value between 0..x-1. Possibly more than one
+ * random number is picked from the random stream to satisfy this.
+ */
+long int ub_random_max(struct ub_randstate* state, long int x);
+
+/**
+ * Delete the random state.
+ * @param state: to delete.
+ */
+void ub_randfree(struct ub_randstate* state);
+
+#endif /* UTIL_RANDOM_H */