Use openssl random number generator

We already have a generator class.  We should use it.  Wrap this into a
function that can be unit tested, and add unit tests.

Note, some files also needed to change name, because random.hpp
conflicts with the built in random, and causes circular build problems.
This commit changes it to ossl_random.

Tested: Unit tests pass.  Now has coverage.

Redfish service validator passes.

Change-Id: I5f8eee1af5f4843a352c6fd0e26d67fd3320ef53
Signed-off-by: Ed Tanous <edtanous@google.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/include/ossl_random.hpp b/include/ossl_random.hpp
new file mode 100644
index 0000000000..2cbec849a9
--- /dev/null
+++ b/include/ossl_random.hpp
@@ -0,0 +1,52 @@
+#pragma once
+
+#include <openssl/rand.h>
+
+#include <iostream>
+#include <limits>
+#include <string>
+
+namespace bmcweb
+{
+
+struct OpenSSLGenerator
+{
+    uint8_t operator()()
+    {
+        uint8_t index = 0;
+        int rc = RAND_bytes(&index, sizeof(index));
+        if (rc != opensslSuccess)
+        {
+            std::cerr << "Cannot get random number\n";
+            err = true;
+        }
+
+        return index;
+    }
+
+    static constexpr uint8_t max()
+    {
+        return std::numeric_limits<uint8_t>::max();
+    }
+    static constexpr uint8_t min()
+    {
+        return std::numeric_limits<uint8_t>::min();
+    }
+
+    bool error() const
+    {
+        return err;
+    }
+
+    // all generators require this variable
+    using result_type = uint8_t;
+
+  private:
+    // RAND_bytes() returns 1 on success, 0 otherwise. -1 if bad function
+    static constexpr int opensslSuccess = 1;
+    bool err = false;
+};
+
+std::string getRandomUUID();
+
+} // namespace bmcweb