test: Only accept a fully valid RANDOM_CTX_SEED

This rejects if the seed is corrupt, truncated, too-long, or otherwise contains non-hex. For example, "RANDOM_CTX_SEED=z". Can be tested with: $ RANDOM_CTX_SEED=z ./src/test/test_bitcoin --log_level=all --run_test=timeoffsets_tests/timeoffsets_warning -- -printtoconsole=1 | grep RANDOM_CTX_SEED test/util/random.cpp:29 operator(): Assertion `uint256::FromHex(num)' failed. Co-authored-by: stickies-v <stickies-v@protonmail.com>
bitcoin · Aug 8, 2024 · 855784d · 855784d
1 parent 1965076
commit 855784d
Showing 1 changed file with 12 additions and 5 deletions.
diff --git a/src/test/util/random.cpp b/src/test/util/random.cpp
@@ -7,32 +7,39 @@
 #include <logging.h>
 #include <random.h>
 #include <uint256.h>
+#include <util/check.h>
 
 #include <cstdlib>
-#include <string>
+#include <iostream>
 
 FastRandomContext g_insecure_rand_ctx;
 
 extern void MakeRandDeterministicDANGEROUS(const uint256& seed) noexcept;
 
 void SeedRandomForTest(SeedRand seedtype)
 {
-    static const std::string RANDOM_CTX_SEED{"RANDOM_CTX_SEED"};
+    constexpr auto 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)}) {
+            if (auto num_parsed{uint256::FromHex(num)}) {
+                return *num_parsed;
+            } else {
+                std::cerr << RANDOM_CTX_SEED << " must be a " << uint256::size() * 2 << " char hex string without '0x'-prefix, was set to: '" << num << "'.\n";
+                std::abort();
+            }
+        }
         // Otherwise use a (truly) random value.
         return GetRandHash();
     }();
 
     const uint256& seed{seedtype == SeedRand::SEED ? ctx_seed : uint256::ZERO};
-    LogPrintf("%s: Setting random seed for current tests to %s=%s\n", __func__, RANDOM_CTX_SEED, seed.GetHex());
+    LogInfo("Setting random seed for current tests to %s=%s\n", RANDOM_CTX_SEED, seed.GetHex());
     MakeRandDeterministicDANGEROUS(seed);
     g_insecure_rand_ctx.Reseed(GetRandHash());
 }