X-Git-Url: https://git.librecmc.org/?a=blobdiff_plain;f=src%2Futil%2Fcrypto_random.c;h=0a092cdcc35d252d29987838a933dae7a47492ef;hb=555214089c7045298f23fea9e060ea931804e75f;hp=0ad1364cb592cdf6e6426acb79d0eafb52221930;hpb=c2017c2ba13736ee1fe4dc9d811d49bee1641ca3;p=oweals%2Fgnunet.git

diff --git a/src/util/crypto_random.c b/src/util/crypto_random.c
index 0ad1364cb..0a092cdcc 100644
--- a/src/util/crypto_random.c
+++ b/src/util/crypto_random.c
@@ -27,19 +27,36 @@
 #include "platform.h"
 #include "gnunet_common.h"
 #include "gnunet_crypto_lib.h"
+#include "gnunet_os_lib.h"
 #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[.
  */
 uint32_t
-GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, 
-			  uint32_t i)
+GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode, uint32_t i)
 {
 #ifdef gcry_fast_random_poll
   static unsigned int invokeCount;
 #endif
   uint32_t ret;
+  uint32_t ul;
 
   GNUNET_assert (i > 0);
 
@@ -50,14 +67,18 @@ GNUNET_CRYPTO_random_u32 (enum GNUNET_CRYPTO_Quality mode,
       if ((invokeCount++ % 256) == 0)
         gcry_fast_random_poll ();
 #endif
-      gcry_randomize ((unsigned char *) &ret,
-                      sizeof (uint32_t),
-		      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;
@@ -85,9 +106,9 @@ GNUNET_CRYPTO_random_permute (enum GNUNET_CRYPTO_Quality mode, unsigned int n)
   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;
@@ -97,26 +118,35 @@ 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
  */
 uint64_t
-GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode,
-                          uint64_t u)
+GNUNET_CRYPTO_random_u64 (enum GNUNET_CRYPTO_Quality mode, uint64_t max)
 {
   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 (uint64_t),
-		      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;
     }
 }
@@ -133,4 +163,98 @@ GNUNET_CRYPTO_random_disable_entropy_gathering ()
 }
 
 
+/**
+ * Process ID of the "find" process that we use for
+ * entropy gathering.
+ */
+static pid_t genproc;
+
+/**
+ * Function called by libgcrypt whenever we are
+ * blocked gathering entropy.
+ */
+static void
+entropy_generator (void *cls,
+                   const char *what, int printchar, int current, int total)
+{
+  unsigned long code;
+  enum GNUNET_OS_ProcessStatusType type;
+  int ret;
+
+  if (0 != strcmp (what, "need_entropy"))
+    return;
+  if (current == total)
+    {
+      if (genproc != 0)
+        {
+          if (0 != PLIBC_KILL (genproc, SIGTERM))
+            GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
+          GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
+          genproc = 0;
+        }
+      return;
+    }
+  if (genproc != 0)
+    {
+      ret = GNUNET_OS_process_status (genproc, &type, &code);
+      if (ret == GNUNET_NO)
+        return;                 /* still running */
+      if (ret == GNUNET_SYSERR)
+        {
+          GNUNET_break (0);
+          return;
+        }
+      if (0 != PLIBC_KILL (genproc, SIGTERM))
+        GNUNET_log_strerror (GNUNET_ERROR_TYPE_ERROR, "kill");
+      GNUNET_break (GNUNET_OK == GNUNET_OS_process_wait (genproc));
+      genproc = 0;
+    }
+  GNUNET_log (GNUNET_ERROR_TYPE_INFO,
+              _("Starting `%s' process to generate entropy\n"), "find");
+  genproc = GNUNET_OS_start_process (NULL, NULL, "sh",
+                                     "sh",
+                                     "-c",
+                                     "exec find / -mount -type f -exec cp {} /dev/null \\; 2>/dev/null",
+                                     NULL);
+}
+
+
+static void
+killfind ()
+{
+  if (genproc != 0)
+    {
+      PLIBC_KILL (genproc, SIGKILL);
+      genproc = 0;
+    }
+}
+
+
+void __attribute__ ((constructor)) GNUNET_CRYPTO_random_init ()
+{
+  SRANDOM (time (NULL));
+  gcry_control (GCRYCTL_DISABLE_SECMEM, 0);
+  if (!gcry_check_version (GCRYPT_VERSION))
+    {
+      fprintf (stderr,
+               _
+               ("libgcrypt has not the expected version (version %s is required).\n"),
+               GCRYPT_VERSION);
+      abort ();
+    }
+#ifdef gcry_fast_random_poll
+  gcry_fast_random_poll ();
+#endif
+  gcry_set_progress_handler (&entropy_generator, NULL);
+  atexit (&killfind);
+}
+
+
+void __attribute__ ((destructor)) GNUNET_CRYPTO_random_fini ()
+{
+  gcry_set_progress_handler (NULL, NULL);
+}
+
+
+
 /* end of crypto_random.c */