Random: implement

include/kvik/random.hpp

@@ -0,0 +1,26 @@
+/**
+ * @file random.hpp
+ * @author Dávid Benko ([email protected])
+ * @brief Random generator
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#pragma once
+
+#include <cstdlib>
+
+namespace kvik
+{
+    /**
+     * @brief Generates `len` truly random bytes in `buf`
+     *
+     * Implementation is plaform dependent.
+     *
+     * @param buf Buffer
+     * @param len Length
+     * @throw kvik::Exception Generation failed
+     */
+    void getRandomBytes(void *buf, size_t len);
+} // namespace kvik

src/espidf/random.cpp

@@ -0,0 +1,20 @@
+/**
+ * @file random.cpp
+ * @author Dávid Benko ([email protected])
+ * @brief Random generator
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#include "esp_random.h"
+
+#include "kvik/random.hpp"
+
+namespace kvik
+{
+    void getRandomBytes(void *buf, size_t len)
+    {
+        esp_fill_random(buf, len);
+    }
+} // namespace kvik

src/linux/random.cpp

@@ -0,0 +1,23 @@
+/**
+ * @file random.cpp
+ * @author Dávid Benko ([email protected])
+ * @brief Random generator
+ *
+ * @copyright Copyright (c) 2024
+ *
+ */
+
+#include <sys/random.h>
+
+#include "kvik/errors.hpp"
+#include "kvik/random.hpp"
+
+namespace kvik
+{
+    void getRandomBytes(void *buf, size_t len)
+    {
+        if (getrandom(buf, len, 0) != len) {
+            throw Exception("Generation failed");
+        }
+    }
+} // namespace kvik

test/tests/random.cpp

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+/**
+ * @file random.cpp
+ * @author Dávid Benko ([email protected])
+ * @copyright Copyright (c) 2024
+ */
+
+#include <catch2/catch_test_macros.hpp>
+
+#include "kvik/random.hpp"
+
+using namespace kvik;
+
+TEST_CASE("Simple random bytes", "[Random]")
+{
+    uint64_t n = 0;
+    REQUIRE_NOTHROW(getRandomBytes(&n, sizeof(n)));
+    REQUIRE(n != 0);
+}
+
+TEST_CASE("Zero length buffer", "[Random]")
+{
+    uint64_t n = 0;
+    REQUIRE_NOTHROW(getRandomBytes(&n, 0));
+    REQUIRE(n == 0);
+}
+
+TEST_CASE("Long buffer", "[Random]")
+{
+    size_t size = 5e6; // 5 MB
+
+    // Allocate big buffer
+    uint8_t *buf = (uint8_t *)calloc(size, 1);
+    REQUIRE(buf != nullptr);
+
+    // Sum up and check last 100 bytes
+    uint16_t sum = 0;
+    for (size_t i = 0; i < 100; i++)
+    {
+        sum += buf[size - i - 1];
+    }
+    REQUIRE(sum == 0);
+
+    REQUIRE_NOTHROW(getRandomBytes(buf, size));
+
+    // Sum up and check again
+    for (size_t i = 0; i < 100; i++)
+    {
+        sum += buf[size - i - 1];
+    }
+    REQUIRE(sum != 0);
+}