1 files changed, 112 insertions, 0 deletions
diff --git a/contrib/libottery/ottery_entropy.c b/contrib/libottery/ottery_entropy.c
new file mode 100644
index 0000000..819a380
--- /dev/null
+++ b/contrib/libottery/ottery_entropy.c
@@ -0,0 +1,112 @@
+/* Libottery by Nick Mathewson.
+
+   This software has been dedicated to the public domain under the CC0
+   public domain dedication.
+
+   To the extent possible under law, the person who associated CC0 with
+   libottery has waived all copyright and related or neighboring rights
+   to libottery.
+
+   You should have received a copy of the CC0 legalcode along with this
+   work in doc/cc0.txt.  If not, see
+      <http://creativecommons.org/publicdomain/zero/1.0/>.
+ */
+#define OTTERY_INTERNAL
+#include "ottery-internal.h"
+#include "ottery.h"
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <string.h>
+
+#define SRC(x) OTTERY_ENTROPY_SRC_ ## x
+#define DOM(x) OTTERY_ENTROPY_DOM_ ## x
+#define FL(x)  OTTERY_ENTROPY_FL_  ## x
+
+#include "ottery_entropy_cryptgenrandom.c"
+#include "ottery_entropy_urandom.c"
+#include "ottery_entropy_rdrand.c"
+#include "ottery_entropy_egd.c"
+
+/** Table of RNG functions and their properties. */
+static struct ottery_randbytes_source {
+  int (*fn)(const struct ottery_entropy_config *,
+            struct ottery_entropy_state *,
+            uint8_t *, size_t);
+  uint32_t flags;
+} RAND_SOURCES[] = {
+#ifdef ENTROPY_SOURCE_CRYPTGENRANDOM
+  ENTROPY_SOURCE_CRYPTGENRANDOM,
+#endif
+#ifdef ENTROPY_SOURCE_URANDOM
+  ENTROPY_SOURCE_URANDOM,
+#endif
+#ifdef ENTROPY_SOURCE_EGD
+  ENTROPY_SOURCE_EGD,
+#endif
+#ifdef ENTROPY_SOURCE_RDRAND
+  ENTROPY_SOURCE_RDRAND,
+#endif
+  { NULL, 0 }
+};
+
+size_t
+ottery_get_entropy_bufsize_(size_t n)
+{
+  return n * (sizeof(RAND_SOURCES)/sizeof(RAND_SOURCES[0]) - 1);
+}
+
+int
+ottery_get_entropy_(const struct ottery_entropy_config *config,
+                    struct ottery_entropy_state *state,
+                     uint32_t select_sources,
+                     uint8_t *bytes, size_t n, size_t *buflen,
+                     uint32_t *flags_out)
+{
+  ssize_t err = OTTERY_ERR_INIT_STRONG_RNG, last_err = 0;
+  int i;
+  uint32_t got = 0;
+  uint8_t *next;
+  const uint32_t disabled_sources = config ? config->disabled_sources : 0;
+
+  memset(bytes, 0, *buflen);
+  next = bytes;
+
+  *flags_out = 0;
+
+  for (i=0; RAND_SOURCES[i].fn; ++i) {
+    uint32_t flags = RAND_SOURCES[i].flags;
+    /* Don't use a disabled source. */
+    if (0 != (flags & disabled_sources))
+      continue;
+    /* If some flags must be set, only use those. */
+    if ((flags & select_sources) != select_sources)
+      continue;
+    /* If we already have input from a certain domain, we don't need more */
+    if ((flags & (got & OTTERY_ENTROPY_DOM_MASK)) != 0)
+      continue;
+    /* If we can't write these bytes, don't try. */
+    if (next + n > bytes + *buflen)
+      break;
+    err = RAND_SOURCES[i].fn(config, state, next, n);
+    if (err == 0) {
+      uint32_t flags = RAND_SOURCES[i].flags;
+      if (config && (flags & config->weak_sources))
+        flags &= ~OTTERY_ENTROPY_FL_STRONG;
+
+      got |= flags;
+      next += n;
+    } else {
+      last_err = err;
+    }
+  }
+
+  /* Do not report success unless at least one source was strong. */
+  if (0 == (got & OTTERY_ENTROPY_FL_STRONG))
+    return last_err ? last_err : OTTERY_ERR_INIT_STRONG_RNG;
+
+  *flags_out = got;
+  *buflen = next - bytes;
+
+  return 0;
+}