X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Futil%2Fcrypto_random.c;h=25ba4db2a81ac94c9172c82c428590288ca7e474;hb=0ea8e006d5f5ef84e31e000607bd24a23f8fc1ed;hp=3f7ac4dd386c64d7e32af3e83736dac6c8f2f36c;hpb=0a217a8df1657b4334b55b0e4a6c7837a8dbcfd9;p=oweals%2Fgnunet.git

diff --git a/src/util/crypto_random.c b/src/util/crypto_random.c
index 3f7ac4dd3..25ba4db2a 100644
--- a/src/util/crypto_random.c
+++ b/src/util/crypto_random.c
@@ -30,15 +30,32 @@
 #include <gcrypt.h>
 
 /**
+ * Create a cryptographically weak pseudo-random number in the interval of 0 to 1.
+ * 
+ * @return number between 0 and 1.
+ */
+static double
+weak_random ()
+{
+  return ((double) RANDOM () / RAND_MAX);
+}
+
+
+/**
+ * Produce a random value.
+ *
+ * @param mode desired quality of the random number
+ * @param i the upper limit (exclusive) for the random number
  * @return a random value in the interval [0,i[.
  */
-unsigned int
-GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, unsigned int i)
+uint32_t
+GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
 {
 #ifdef gcry_fast_random_poll
   static unsigned int invokeCount;
 #endif
-  unsigned int ret;
+  uint32_t ret;
+  uint32_t ul;
 
   GNUNET_assert (i > 0);
 
@@ -49,16 +66,18 @@ GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, unsigned int i)
       if ((invokeCount++ % 256) == 0)
         gcry_fast_random_poll ();
 #endif
-      ret = rand ();            /* in case gcry_randomize fails,
-                                   we at least get a pseudo-
-                                   random number this way */
-      gcry_randomize ((unsigned char *) &ret,
-                      sizeof (unsigned int), GCRY_STRONG_RANDOM);
+      ul = UINT32_MAX - (UINT32_MAX % i);
+      do
+	{
+	  gcry_randomize ((unsigned char *) &ret,
+			  sizeof (uint32_t), GCRY_STRONG_RANDOM);
+	}
+      while (ret >= ul);
       return ret % i;
     }
   else
     {
-      ret = i * ((double) RANDOM () / RAND_MAX);
+      ret = i * weak_random ();
       if (ret >= i)
         ret = i - 1;
       return ret;
@@ -80,15 +99,15 @@ GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
   unsigned int *ret;
   unsigned int i;
   unsigned int tmp;
-  unsigned int x;
+  uint32_t x;
 
   GNUNET_assert (n > 0);
-  ret = GNUNET_malloc (n * sizeof (int));
+  ret = GNUNET_malloc (n * sizeof (unsigned int));
   for (i = 0; i < n; i++)
     ret[i] = i;
-  for (i = 0; i < n; i++)
+  for (i = n - 1; i > 0; i--)
     {
-      x = GNUNET_CRYPTO_random_u32 (mode, n);
+      x = GNUNET_CRYPTO_random_u32 (mode, i+1);
       tmp = ret[x];
       ret[x] = ret[i];
       ret[i] = tmp;
@@ -98,25 +117,35 @@ GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
 
 /**
  * Random on unsigned 64-bit values.
+ *
+ *
+ * @param mode desired quality of the random number
+ * @param max value returned will be in range [0,max) (exclusive)
+ * @return random 64-bit number
  */
-unsigned long long
-GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode,
-                          unsigned long long u)
+uint64_t
+GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
 {
-  unsigned long long ret;
+  uint64_t ret;
+  uint64_t ul;
 
-  GNUNET_assert (u > 0);
+  GNUNET_assert (max > 0);
   if (mode == GNUNET_CRYPTO_QUALITY_STRONG)
     {
-      gcry_randomize ((unsigned char *) &ret,
-                      sizeof (unsigned long long), GCRY_STRONG_RANDOM);
-      return ret % u;
+      ul = UINT64_MAX - (UINT64_MAX % max);
+      do
+	{
+	  gcry_randomize ((unsigned char *) &ret,
+			  sizeof (uint64_t), GCRY_STRONG_RANDOM);
+	}
+      while (ret >= ul);
+      return ret % max;
     }
   else
     {
-      ret = u * ((double) RANDOM () / RAND_MAX);
-      if (ret >= u)
-        ret = u - 1;
+      ret = max * weak_random ();
+      if (ret >= max)
+        ret = max - 1;
       return ret;
     }
 }
@@ -132,5 +161,12 @@ GNUNET_CRYPTO_random_disable_entropy_gathering ()
   gcry_control (GCRYCTL_ENABLE_QUICK_RANDOM, 0);
 }
 
+/**
+ * Initializer
+ */
+void __attribute__ ((constructor)) GNUNET_util_random_init ()
+{
+  SRANDOM (time (NULL));
+}
 
 /* end of crypto_random.c */