random.h File Reference

Thread safe random functions. More...

Functions
void	ub_systemseed (unsigned int seed)
	Initialize the system randomness.
struct ub_randstate *	ub_initstate (unsigned int seed, struct ub_randstate *from)
	Initialize a random generator state for use.
long int	ub_random (struct ub_randstate *state)
	Generate next random number from the state passed along.
long int	ub_random_max (struct ub_randstate *state, long int x)
	Generate random number between 0 and x-1.
void	ub_randfree (struct ub_randstate *state)
	Delete the random state.

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Detailed Description

Thread safe random functions.

Similar to arc4random() with an explicit initialisation routine.

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Function Documentation

void ub_systemseed

(

unsigned int

seed

)

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.

Parameters:

seed,:

seed value to create state (if no good entropy is found).

References log_err(), verbose(), and VERB_OPS.

Referenced by daemon_init(), ub_arc4random_stir(), and ub_initstate().

struct ub_randstate* ub_initstate	(	unsigned int	seed,
		struct ub_randstate *	from
	)		[read]

Initialize a random generator state for use.

Parameters:

seed,:	seed value to create state contents. (ignored for arc4random).
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.

Returns:

new state or NULL alloc failure.

References log_err(), ub_systemseed(), and ub_arc4random_stir().

Referenced by daemon_create_workers(), worker_create(), ub_ctx_create(), libworker_setup(), and rnd_test().

long int ub_random

(

struct ub_randstate *

state

)

Generate next random number from the state passed along.

Thread safe, so random numbers are repeatable.

Parameters:

state,:

must have been initialised with ub_initstate.

Returns:

: random 31 bit value.

References ub_randstate::rc4_ready, ub_arc4random_stir(), ub_randstate::rc4, and MAX_VALUE.

Referenced by daemon_create_workers(), libworker_setup(), select_id(), pending_tcp_query(), serviced_perturb_qname(), rnd_test(), ub_arc4random_stir(), and ub_random_max().

long int ub_random_max	(	struct ub_randstate *	state,
		long int	x
	)

Generate random number between 0 and x-1.

No modulo bias.

Parameters:

state,:	must have been initialised with ub_initstate.
x,:	an upper limit. not (negative or zero). must be smaller than 2**31.

Returns:

: random value between 0..x-1. Possibly more than one random number is picked from the random stream to satisfy this.

References MAX_VALUE, and ub_random().

Referenced by daemon_get_shufport(), iter_server_selection(), iter_ns_probability(), pick_outgoing_tcp(), select_ifport(), rnd_test(), and calc_next_probe().

void ub_randfree

(

struct ub_randstate *

state

)

Delete the random state.

Parameters:

state,:

to delete.

Referenced by daemon_delete(), worker_delete(), ub_ctx_create(), ub_ctx_delete(), libworker_delete(), and rnd_test().