Commit 2ccf3268 authored by George Kadianakis's avatar George Kadianakis
Browse files

Implement and test probability distributions used by WTF-PAD. 



This project introduces the prob_distr.c subsystem which implements all the
probability distributions that WTF-PAD needs. It also adds unittests for all of
them.

Code and tests courtesy of Riastradh.

Co-authored-by: default avatarTaylor R Campbell <campbell+tor@mumble.net>
Co-authored-by: default avatarMike Perry <mikeperry-git@torproject.org>
parent 8ad497bb

src/core/or/circuitpadding.c

+4 −4
Original line number Diff line number Diff line
@@ -516,10 +516,10 @@ circpad_distribution_sample(circpad_distribution_t dist) 
       * param1 is Alpha, param2 is Beta */

      return dist.param1 * pow(p/(1.0-p), 1.0/dist.param2);

    case CIRCPAD_DIST_GEOMETRIC:

      p = crypto_rand_double();

      /* https://github.com/distributions-io/geometric-quantile/

       * param1 is 'p' (success probability) */

      return ceil(tor_mathlog(1.0-p)/tor_mathlog(1.0-dist.param1));

      {

        /* param1 is 'p' (success probability) */

        return geometric_sample(dist.param1);

      }

    case CIRCPAD_DIST_WEIBULL:

      p = crypto_rand_double();

      /* https://en.wikipedia.org/wiki/Weibull_distribution \

src/lib/crypt_ops/crypto_rand.c

+11 −0
Original line number Diff line number Diff line
@@ -528,6 +528,17 @@ crypto_rand_unmocked(char *to, size_t n) 
#endif

}



/**

 * Draw an unsigned 32-bit integer uniformly at random.

 */

uint32_t

crypto_rand_uint32(void)

{

  uint32_t rand;

  crypto_rand((void*)&rand, sizeof(rand));

  return rand;

}



/**

 * Return a pseudorandom integer, chosen uniformly from the values

 * between 0 and <b>max</b>-1 inclusive.  <b>max</b> must be between 1 and

src/lib/crypt_ops/crypto_rand.h

+1 −0
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ int crypto_rand_int(unsigned int max); 
int crypto_rand_int_range(unsigned int min, unsigned int max);

uint64_t crypto_rand_uint64_range(uint64_t min, uint64_t max);

time_t crypto_rand_time_range(time_t min, time_t max);

uint32_t crypto_rand_uint32(void);

uint64_t crypto_rand_uint64(uint64_t max);

double crypto_rand_double(void);

struct tor_weak_rng_t;

src/lib/math/.may_include

+2 −0
Original line number Diff line number Diff line
@@ -3,3 +3,5 @@ orconfig.h 
lib/cc/*.h

lib/log/*.h

lib/math/*.h

lib/testsupport/*.h

lib/crypt_ops/*.h

src/lib/math/fp.c

+25 −0
Original line number Diff line number Diff line
@@ -117,3 +117,28 @@ ENABLE_GCC_WARNING(double-promotion) 
ENABLE_GCC_WARNING(float-conversion)

#endif

}



/* isinf() wrapper for tor */

int

tor_isinf(double x)

{

  /* Same as above, work around the "double promotion" warnings */

#if defined(MINGW_ANY) && GCC_VERSION >= 409

#define PROBLEMATIC_FLOAT_CONVERSION_WARNING

DISABLE_GCC_WARNING(float-conversion)

#endif /* defined(MINGW_ANY) && GCC_VERSION >= 409 */

#if defined(__clang__)

#if __has_warning("-Wdouble-promotion")

#define PROBLEMATIC_DOUBLE_PROMOTION_WARNING

DISABLE_GCC_WARNING(double-promotion)

#endif

#endif /* defined(__clang__) */

  return isinf(x);

#ifdef PROBLEMATIC_DOUBLE_PROMOTION_WARNING

ENABLE_GCC_WARNING(double-promotion)

#endif

#ifdef PROBLEMATIC_FLOAT_CONVERSION_WARNING

ENABLE_GCC_WARNING(float-conversion)

#endif

}