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

sipa · Warrows · commit 64e03e6de1a6 · 2019-07-31T11:52:17.000+02:00
diff --git a/src/random.cpp b/src/random.cpp
@@ -396,6 +396,7 @@ 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);
diff --git a/src/test/random_tests.cpp b/src/test/random_tests.cpp
@@ -35,11 +35,18 @@ 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)

Original file line number	Diff line number	Diff line change
`@@ -396,6 +396,7 @@ uint256 FastRandomContext::rand256()`
`396`	`396`
`397`	`397`	`std::vector<unsigned char> FastRandomContext::randbytes(size_t len)`
`398`	`398`	`{`
	`399`	`+ if (requires_seed) RandomSeed();`
`399`	`400`	`std::vector<unsigned char> ret(len);`
`400`	`401`	`if (len > 0) {`
`401`	`402`	`rng.Output(&ret[0], len);`