random: use uint256::FromHex for RANDOM_CTX_SEED

Removes dependency on unsafe and deprecated uint256S. This makes parsing more strict, by requiring RANDOM_CTX_SEED to be a 64 char hex string, whereas previously any string would be accepted, with non-hex characters silently ignored and strings longer than 64 characters silently trimmed. Additionally, and unrelatedly, make RANDOM_CTX_SEED inline constexpr
bitcoin · Aug 7, 2024 · d045fc7 · d045fc7
1 parent 31a3cd2
commit d045fc7
Showing 1 changed file with 6 additions and 5 deletions.
diff --git a/src/test/util/random.cpp b/src/test/util/random.cpp
@@ -7,26 +7,27 @@
 #include <logging.h>
 #include <random.h>
 #include <uint256.h>
+#include <util/check.h>
 
 #include <cstdlib>
-#include <string>
 
 FastRandomContext g_insecure_rand_ctx;
 
+inline constexpr const char* RANDOM_CTX_SEED{"RANDOM_CTX_SEED"};
+
 extern void MakeRandDeterministicDANGEROUS(const uint256& seed) noexcept;
 
 void SeedRandomForTest(SeedRand seedtype)
 {
-    static const std::string RANDOM_CTX_SEED{"RANDOM_CTX_SEED"};
-
     // Do this once, on the first call, regardless of seedtype, because once
     // MakeRandDeterministicDANGEROUS is called, the output of GetRandHash is
     // no longer truly random. It should be enough to get the seed once for the
     // process.
     static const uint256 ctx_seed = []() {
         // If RANDOM_CTX_SEED is set, use that as seed.
-        const char* num = std::getenv(RANDOM_CTX_SEED.c_str());
-        if (num) return uint256S(num);
+        if (const char* num{std::getenv(RANDOM_CTX_SEED)}) {
+            return *Assert(uint256::FromHex(num)); // RANDOM_CTX_SEED must be a 64 char hex string
+        }
         // Otherwise use a (truly) random value.
         return GetRandHash();
     }();