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readability code clean-up (#548)
* readability code clean-up * readability code clean-up
This commit is contained in:
Logan oos Even
GitHub
parent
4e6d9a8f43
commit
ab4f507012
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@ -23,34 +23,36 @@
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#include <stdint.h>
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#include <stddef.h>
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#include <time.h> // time, clock
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#include <time.h> /* time, clock */
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#include "n2n.h" /* traceEvent */
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#include "n2n.h" // traceEvent
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// syscall and inquiring random number from hardware generators might fail, so we will retry
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#define RND_RETRIES 1000
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#if defined (__linux__)
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#include <sys/syscall.h> // syscall, SYS_getrandom
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#include <sys/syscall.h> /* syscall, SYS_getrandom */
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#ifdef SYS_getrandom
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#define GRND_NONBLOCK 1
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#include <errno.h> // errno, EAGAIN
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#include <errno.h> /* errno, EAGAIN */
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#endif
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#endif
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#if defined (__RDRND__) || defined (__RDSEED__)
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#include <immintrin.h> // _rdrand64_step, rdseed4_step
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#include <immintrin.h> /* _rdrand64_step, rdseed4_step */
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#endif
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/* The WIN32 code is still untested and thus commented, also see random_numbers.c
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#if defined (WIN32)
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#include <Wincrypt.h> // HCTYPTPROV, Crypt*-functions
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#endif
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// the WIN32 code is still untested and thus commented, also see random_numbers.c
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/*
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#if defined (WIN32)
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#include <Wincrypt.h> // HCTYPTPROV, Crypt*-functions
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#endif
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*/
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typedef struct rn_generator_state_t {
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uint64_t a, b;
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uint64_t a, b;
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} rn_generator_state_t;
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typedef struct splitmix64_state_t {
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@ -60,9 +62,9 @@ typedef struct splitmix64_state_t {
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int n2n_srand (uint64_t seed);
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uint64_t n2n_rand ();
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uint64_t n2n_rand (void);
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uint64_t n2n_seed ();
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uint64_t n2n_seed (void);
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uint32_t n2n_rand_sqr (uint32_t max_n);
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@ -20,211 +20,226 @@
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#include "random_numbers.h"
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/* The following code offers an alterate pseudo random number generator
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namely XORSHIFT128+ to use instead of C's rand(). Its performance is
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on par with C's rand().
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*/
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// the following code offers an alterate pseudo random number generator
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// namely XORSHIFT128+ to use instead of C's rand()
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// its performance is on par with C's rand()
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/* The state must be seeded in a way that it is not all zero, choose some
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arbitrary defaults (in this case: taken from splitmix64) */
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// the state must be seeded in a way that it is not all zero, choose some
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// arbitrary defaults (in this case: taken from splitmix64)
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static rn_generator_state_t rn_current_state = {
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.a = 0x9E3779B97F4A7C15,
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.b = 0xBF58476D1CE4E5B9 };
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.a = 0x9E3779B97F4A7C15,
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.b = 0xBF58476D1CE4E5B9
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};
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/* used for mixing the initializing seed */
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// used for mixing the initializing seed
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static uint64_t splitmix64 (splitmix64_state_t *state) {
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uint64_t result = state->s;
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uint64_t result = state->s;
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state->s = result + 0x9E3779B97F4A7C15;
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state->s = result + 0x9E3779B97F4A7C15;
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result = (result ^ (result >> 30)) * 0xBF58476D1CE4E5B9;
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result = (result ^ (result >> 27)) * 0x94D049BB133111EB;
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result = (result ^ (result >> 30)) * 0xBF58476D1CE4E5B9;
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result = (result ^ (result >> 27)) * 0x94D049BB133111EB;
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return result ^ (result >> 31);
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return result ^ (result >> 31);
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}
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int n2n_srand (uint64_t seed) {
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uint8_t i;
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splitmix64_state_t smstate = {seed};
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uint8_t i;
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splitmix64_state_t smstate = { seed };
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rn_current_state.a = 0;
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rn_current_state.b = 0;
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rn_current_state.a = 0;
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rn_current_state.b = 0;
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rn_current_state.a = splitmix64 (&smstate);
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rn_current_state.b = splitmix64 (&smstate);
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rn_current_state.a = splitmix64 (&smstate);
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rn_current_state.b = splitmix64 (&smstate);
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/* the following lines could be deleted as soon as it is formally prooved that
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there is no seed leading to (a == b == 0). Until then, just to be safe: */
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if ( (rn_current_state.a == 0) && (rn_current_state.b == 0) ) {
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rn_current_state.a = 0x9E3779B97F4A7C15;
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rn_current_state.b = 0xBF58476D1CE4E5B9;
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}
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// the following lines could be deleted as soon as it is formally prooved that
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// there is no seed leading to (a == b == 0). until then, just to be safe:
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if((rn_current_state.a == 0) && (rn_current_state.b == 0)) {
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rn_current_state.a = 0x9E3779B97F4A7C15;
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rn_current_state.b = 0xBF58476D1CE4E5B9;
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}
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// stabilize in unlikely case of weak state with only a few bits set
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for(i = 0; i < 32; i++)
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n2n_rand();
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// stabilize in unlikely case of weak state with only a few bits set
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for(i = 0; i < 32; i++)
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n2n_rand();
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return 0;
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return 0;
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}
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/* The following code of xorshift128p was taken from
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https://en.wikipedia.org/wiki/Xorshift as of July, 2019
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and thus is considered public domain. */
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uint64_t n2n_rand () {
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// the following code of xorshift128p was taken from
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// https://en.wikipedia.org/wiki/Xorshift as of July, 2019
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// and thus is considered public domain
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uint64_t n2n_rand (void) {
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uint64_t t = rn_current_state.a;
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uint64_t const s = rn_current_state.b;
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uint64_t t = rn_current_state.a;
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uint64_t const s = rn_current_state.b;
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rn_current_state.a = s;
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t ^= t << 23;
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t ^= t >> 17;
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t ^= s ^ (s >> 26);
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rn_current_state.b = t;
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rn_current_state.a = s;
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t ^= t << 23;
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t ^= t >> 17;
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t ^= s ^ (s >> 26);
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rn_current_state.b = t;
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return t + s;
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return t + s;
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}
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/* The following code tries to gather some entropy from several sources
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for use as seed. Note, that this code does not set the random generator
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state yet, a call to n2n_srand ( n2n_seed() ) would do. */
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// the following code tries to gather some entropy from several sources
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// for use as seed. Note, that this code does not set the random generator
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// state yet, a call to n2n_srand (n2n_seed()) would do
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uint64_t n2n_seed (void) {
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uint64_t seed = 0;
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uint64_t ret = 0;
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size_t i;
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uint64_t seed = 0; /* this could even go uninitialized */
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uint64_t ret = 0; /* this could even go uninitialized */
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size_t i;
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#ifdef SYS_getrandom
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int rc = -1;
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for(i = 0; (i < RND_RETRIES) && (rc != sizeof(seed)); i++) {
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rc = syscall (SYS_getrandom, &seed, sizeof(seed), GRND_NONBLOCK);
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// if successful, rc should contain the requested number of random bytes
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if(rc != sizeof(seed)) {
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if (errno != EAGAIN) {
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traceEvent(TRACE_ERROR, "n2n_seed faced error errno=%u from getrandom syscall.", errno);
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break;
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}
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int rc = -1;
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for(i = 0; (i < RND_RETRIES) && (rc != sizeof(seed)); i++) {
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rc = syscall (SYS_getrandom, &seed, sizeof(seed), GRND_NONBLOCK);
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// if successful, rc should contain the requested number of random bytes
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if(rc != sizeof(seed)) {
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if (errno != EAGAIN) {
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traceEvent(TRACE_ERROR, "n2n_seed faced error errno=%u from getrandom syscall.", errno);
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break;
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}
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}
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}
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// if we still see an EAGAIN error here, we must have run out of retries
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if(errno == EAGAIN) {
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traceEvent(TRACE_ERROR, "n2n_seed saw getrandom syscall indicate not being able to provide enough entropy yet.");
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}
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}
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// if we still see an EAGAIN error here, we must have run out of retries
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if(errno == EAGAIN) {
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traceEvent(TRACE_ERROR, "n2n_seed saw getrandom syscall indicate not being able to provide enough entropy yet.");
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}
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#endif
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// as we want randomness, it does no harm to add up even uninitialized values or
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// erroneously arbitrary values returned from the syscall for the first time
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ret += seed;
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// as we want randomness, it does no harm to add up even uninitialized values or
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// erroneously arbitrary values returned from the syscall for the first time
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ret += seed;
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// __RDRND__ is set only if architecturual feature is set, e.g. compile with -march=native
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// __RDRND__ is set only if architecturual feature is set, e.g. compiled with -march=native
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#ifdef __RDRND__
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for(i = 0; i < RND_RETRIES; i++) {
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if(_rdrand64_step ((unsigned long long*)&seed)) {
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// success!
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// from now on, we keep this inside the loop because in case of failure
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// and with unchanged values, we do not want to double the previous value
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ret += seed;
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break;
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for(i = 0; i < RND_RETRIES; i++) {
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if(_rdrand64_step((unsigned long long*)&seed)) {
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// success!
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// from now on, we keep this inside the loop because in case of failure
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// and with unchanged values, we do not want to double the previous value
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ret += seed;
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break;
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}
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// continue loop to try again otherwise
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}
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if(i == RND_RETRIES) {
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traceEvent(TRACE_ERROR, "n2n_seed was not able to get a hardware generated random number from RDRND.");
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}
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// continue loop to try again otherwise
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}
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if(i == RND_RETRIES){
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traceEvent(TRACE_ERROR, "n2n_seed was not able to get a hardware generated random number from RDRND.");
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}
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#endif
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// __RDSEED__ ist set only if architecturual feature is set, e.g. compile with -march=native
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// __RDSEED__ ist set only if architecturual feature is set, e.g. compile with -march=native
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#ifdef __RDSEED__
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for(i = 0; i < RND_RETRIES; i++) {
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if(_rdseed64_step((unsigned long long*)&seed)) {
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// success!
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ret += seed;
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break;
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for(i = 0; i < RND_RETRIES; i++) {
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if(_rdseed64_step((unsigned long long*)&seed)) {
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// success!
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ret += seed;
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break;
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}
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// continue loop to try again otherwise
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}
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if(i == RND_RETRIES) {
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traceEvent(TRACE_ERROR, "n2n_seed was not able to get a hardware generated random number from RDSEED.");
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}
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// continue loop to try again otherwise
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}
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if(i == RND_RETRIES){
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traceEvent(TRACE_ERROR, "n2n_seed was not able to get a hardware generated random number from RDSEED.");
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}
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#endif
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/* The WIN32 code is still untested and thus commented
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#ifdef WIN32
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HCRYPTPROV crypto_provider;
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CryptAcquireContext (&crypto_provider, NULL, (LPCWSTR)L"Microsoft Base Cryptographic Provider v1.0",
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PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
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CryptGenRandom (crypto_provider, 8, &seed);
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CryptReleaseContext (crypto_provider, 0);
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ret += seed;
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#endif */
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// the following WIN32 code is still untested and thus commented
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/*
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#ifdef WIN32
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HCRYPTPROV crypto_provider;
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CryptAcquireContext (&crypto_provider, NULL, (LPCWSTR)L"Microsoft Base Cryptographic Provider v1.0",
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PROV_RSA_FULL, CRYPT_VERIFYCONTEXT);
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CryptGenRandom (crypto_provider, 8, &seed);
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CryptReleaseContext (crypto_provider, 0);
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ret += seed;
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#endif
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*/
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seed = time(NULL); // UTC in seconds
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ret += seed;
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seed = time(NULL); /* UTC in seconds */
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ret += seed;
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seed = clock() * 18444244737; // clock() = ticks since program start
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ret += seed;
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seed = clock(); /* ticks since program start */
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seed *= 18444244737;
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ret += seed;
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return ret;
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return ret;
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}
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/* an integer squrare root approximation
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* from https://stackoverflow.com/a/1100591. */
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static int ftbl [33] = {0,1,1,2,2,4,5,8,11,16,22,32,45,64,90,128,181,256,362,512,724,1024,1448,2048,2896,4096,5792,8192,11585,16384,23170,32768,46340};
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static int ftbl2[32] = { 32768,33276,33776,34269,34755,35235,35708,36174,36635,37090,37540,37984,38423,38858,39287,39712,40132,40548,40960,41367,41771,42170,42566,42959,43347,43733,44115,44493,44869,45241,45611,45977};
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// an integer squrare root approximation
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// from https://stackoverflow.com/a/1100591
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static int ftbl[33] = {
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0, 1, 1, 2, 2, 4, 5, 8, 11, 16, 22, 32, 45, 64, 90,
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128, 181 ,256 ,362, 512, 724, 1024, 1448, 2048, 2896,
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4096, 5792, 8192, 11585, 16384, 23170, 32768, 46340 };
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static int i_sqrt(int val) {
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static int ftbl2[32] = {
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32768, 33276, 33776, 34269, 34755, 35235, 35708, 36174,
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36635, 37090, 37540, 37984, 38423, 38858, 39287, 39712,
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40132, 40548, 40960, 41367, 41771, 42170, 42566, 42959,
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43347, 43733, 44115, 44493, 44869, 45241, 45611, 45977 };
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int cnt = 0;
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int t = val;
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while(t) {
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cnt++;
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t>>=1;
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}
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static int i_sqrt (int val) {
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if(6 >= cnt)
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t = (val << (6-cnt));
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else
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t = (val >> (cnt-6));
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int cnt = 0;
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int t = val;
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return (ftbl[cnt] * ftbl2[t & 31]) >> 15;
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while(t) {
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cnt++;
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t>>=1;
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}
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if(6 >= cnt)
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t = (val << (6-cnt));
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else
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t = (val >> (cnt-6));
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return (ftbl[cnt] * ftbl2[t & 31]) >> 15;
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}
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static int32_t int_sqrt(int val) {
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static int32_t int_sqrt (int val) {
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int ret;
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int ret;
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ret = i_sqrt (val);
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ret += i_sqrt (val - ret * ret) / 16;
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ret = i_sqrt (val);
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ret += i_sqrt (val - ret * ret) / 16;
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return ret;
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return ret;
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}
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// returns a random number from [0, max_n] with higher probability towards the borders
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uint32_t n2n_rand_sqr (uint32_t max_n) {
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uint32_t raw_max = 0;
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uint32_t raw_rnd = 0;
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int32_t ret = 0;
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uint32_t raw_max = 0;
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uint32_t raw_rnd = 0;
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int32_t ret = 0;
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raw_max = (max_n+2) * (max_n+2);
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raw_rnd = n2n_rand() % (raw_max);
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raw_max = (max_n+2) * (max_n+2);
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raw_rnd = n2n_rand() % (raw_max);
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ret = int_sqrt(raw_rnd) / 2;
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ret = (raw_rnd & 1) ? ret : -ret;
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ret = max_n / 2 + ret;
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ret = int_sqrt(raw_rnd) / 2;
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ret = (raw_rnd & 1) ? ret : -ret;
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ret = max_n / 2 + ret;
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if (ret < 0) ret = 0;
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if (ret > max_n) ret = max_n;
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if(ret < 0)
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ret = 0;
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if (ret > max_n)
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ret = max_n;
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return ret;
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return ret;
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}
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