1 files changed, 50 insertions, 0 deletions
diff --git a/ext/libressl/crypto/compat/getentropy_win.c b/ext/libressl/crypto/compat/getentropy_win.c
new file mode 100644
index 0000000..64514b3
--- /dev/null
+++ b/ext/libressl/crypto/compat/getentropy_win.c
@@ -0,0 +1,50 @@
+/*	$OpenBSD: getentropy_win.c,v 1.6 2020/11/11 10:41:24 bcook Exp $	*/
+
+/*
+ * Copyright (c) 2014, Theo de Raadt <deraadt@openbsd.org> 
+ * Copyright (c) 2014, Bob Beck <beck@obtuse.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ *
+ * Emulation of getentropy(2) as documented at:
+ * http://man.openbsd.org/getentropy.2
+ */
+
+#include <windows.h>
+#include <bcrypt.h>
+#include <errno.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+int	getentropy(void *buf, size_t len);
+
+/*
+ * On Windows, BCryptGenRandom with BCRYPT_USE_SYSTEM_PREFERRED_RNG is supposed
+ * to be a well-seeded, cryptographically strong random number generator.
+ * https://docs.microsoft.com/en-us/windows/win32/api/bcrypt/nf-bcrypt-bcryptgenrandom
+ */
+int
+getentropy(void *buf, size_t len)
+{
+	if (len > 256) {
+		errno = EIO;
+		return (-1);
+	}
+
+	if (FAILED(BCryptGenRandom(NULL, buf, len, BCRYPT_USE_SYSTEM_PREFERRED_RNG))) {
+		errno = EIO;
+		return (-1);
+	}
+
+	return (0);
+}