lib: Add secure random generator

This adds a secure random number generator. It will use OS specific
calls with a fallback to OpenSSL if available.

1 files changed, 51 insertions, 0 deletions

diff --git a/src/lib/random.c b/src/lib/random.c
new file mode 100644
index 00000000..d6bde0f8
--- /dev/null
+++ b/src/lib/random.c
@@ -0,0 +1,51 @@
+/*
+ * Ouroboros - Copyright (C) 2016 - 2017
+ *
+ * Pseudo random generator
+ *
+ *    Dimitri Staessens <dimitri.staessens@ugent.be>
+ *    Sander Vrijders   <sander.vrijders@ugent.be>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * version 2.1 as published by the Free Software Foundation.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301 USA
+ */
+
+#include <ouroboros/random.h>
+
+#if defined(HAVE_SYS_RANDOM)
+#include <sys/random.h>
+#elif defined(__FreeBSD__)
+#include <stdlib.h>
+#elif defined(HAVE_OPENSSL)
+#include <openssl/rand.h>
+#include <limits.h>
+#endif
+
+int random_buffer(void * buf,
+                  size_t len)
+{
+#if defined(HAVE_SYS_RANDOM)
+        return getrandom(buf, len, GRND_NONBLOCK); /* also in glibc 2.25 */
+#elif defined(__FreeBSD__)
+        return arc4random_buf(buf, len);
+#elif defined(HAVE_OPENSSL)
+        if (len > 0 && len < INT_MAX)
+                return RAND_bytes((unsigned char *) buf, (int) len);
+        return -1;
+#else
+        (void) buf;
+        (void) len;
+        return -1;
+#endif
+}