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-rw-r--r--src/random.c83
1 files changed, 83 insertions, 0 deletions
diff --git a/src/random.c b/src/random.c
new file mode 100644
index 0000000..9688d35
--- /dev/null
+++ b/src/random.c
@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2018 Yubico AB. All rights reserved.
+ * Use of this source code is governed by a BSD-style
+ * license that can be found in the LICENSE file.
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#ifdef HAVE_SYS_RANDOM_H
+#include <sys/random.h>
+#endif
+
+#include <fcntl.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif
+
+#include "fido.h"
+
+#if defined(_WIN32)
+#include <windows.h>
+
+#include <winternl.h>
+#include <winerror.h>
+#include <stdio.h>
+#include <bcrypt.h>
+#include <sal.h>
+
+int
+fido_get_random(void *buf, size_t len)
+{
+ NTSTATUS status;
+
+ status = BCryptGenRandom(NULL, buf, (ULONG)len,
+ BCRYPT_USE_SYSTEM_PREFERRED_RNG);
+
+ if (!NT_SUCCESS(status))
+ return (-1);
+
+ return (0);
+}
+#elif defined(HAVE_ARC4RANDOM_BUF)
+int
+fido_get_random(void *buf, size_t len)
+{
+ arc4random_buf(buf, len);
+ return (0);
+}
+#elif defined(HAVE_GETRANDOM)
+int
+fido_get_random(void *buf, size_t len)
+{
+ ssize_t r;
+
+ if ((r = getrandom(buf, len, 0)) < 0 || (size_t)r != len)
+ return (-1);
+
+ return (0);
+}
+#elif defined(HAVE_DEV_URANDOM)
+int
+fido_get_random(void *buf, size_t len)
+{
+ int fd = -1;
+ int ok = -1;
+ ssize_t r;
+
+ if ((fd = open(FIDO_RANDOM_DEV, O_RDONLY)) < 0)
+ goto fail;
+ if ((r = read(fd, buf, len)) < 0 || (size_t)r != len)
+ goto fail;
+
+ ok = 0;
+fail:
+ if (fd != -1)
+ close(fd);
+
+ return (ok);
+}
+#else
+#error "please provide an implementation of fido_get_random() for your platform"
+#endif /* _WIN32 */