Fix: sessiond: instance uuid is not sufficiently unique

[lttng-tools.git] / src / common / random.hpp

diff --git a/src/common/random.hpp b/src/common/random.hpp
new file mode 100644 (file)
index 0000000..0430485
--- /dev/null
+++ b/src/common/random.hpp
@@ -0,0 +1,49 @@
+/*
+ * Copyright (C) 2023 Jérémie Galarneau <jeremie.galarneau@efficios.com>
+ *
+ * SPDX-License-Identifier: LGPL-2.1-only
+ *
+ */
+
+#ifndef LTTNG_RANDOM_H
+#define LTTNG_RANDOM_H
+
+#include "exception.hpp"
+
+#include <cstddef>
+#include <string>
+
+namespace lttng {
+namespace random {
+
+using seed_t = unsigned int;
+
+class production_error : public ::lttng::runtime_error {
+public:
+       explicit production_error(const std::string& msg,
+                       const char *file_name,
+                       const char *function_name,
+                       unsigned int line_number);
+};
+
+/*
+ * Get a seed from a reliable source of randomness without blocking, raising
+ * an exception on failure.
+ */
+seed_t produce_true_random_seed();
+
+/*
+ * Get a random seed making a best-effort to use a true randomness source,
+ * but falling back to a pseudo-random seed based on the time and various system
+ * configuration values on failure.
+ *
+ * Note that this function attempts to use the urandom device, which will block
+ * in the unlikely event that its pool is uninitialized, on platforms that don't
+ * provide getrandom().
+ */
+seed_t produce_best_effort_random_seed();
+
+} /* namespace random */
+} /* namespace lttng */
+
+#endif /* LTTNG_RANDOM_H */