Bugfix: randbytes should seed when needed (non reachable issue)

Author: sipa

src/random.cpp

@@ -398,6 +398,7 @@ uint256 FastRandomContext::rand256()
 
 std::vector<unsigned char> FastRandomContext::randbytes(size_t len)
 {
+    if (requires_seed) RandomSeed();
     std::vector<unsigned char> ret(len);
     if (len > 0) {
         rng.Output(&ret[0], len);

src/test/random_tests.cpp

@@ -38,11 +38,18 @@ BOOST_AUTO_TEST_CASE(fastrandom_tests)
     BOOST_CHECK(ctx1.randbytes(50) == ctx2.randbytes(50));
 
     // Check that a nondeterministic ones are not
-    FastRandomContext ctx3;
-    FastRandomContext ctx4;
-    BOOST_CHECK(ctx3.rand64() != ctx4.rand64()); // extremely unlikely to be equal
-    BOOST_CHECK(ctx3.rand256() != ctx4.rand256());
-    BOOST_CHECK(ctx3.randbytes(7) != ctx4.randbytes(7));
+    {
+        FastRandomContext ctx3, ctx4;
+        BOOST_CHECK(ctx3.rand64() != ctx4.rand64()); // extremely unlikely to be equal
+    }
+    {
+        FastRandomContext ctx3, ctx4;
+        BOOST_CHECK(ctx3.rand256() != ctx4.rand256());
+    }
+    {
+        FastRandomContext ctx3, ctx4;
+        BOOST_CHECK(ctx3.randbytes(7) != ctx4.randbytes(7));
+    }
 }
 
 BOOST_AUTO_TEST_CASE(fastrandom_randbits)