From: Nick Mathewson <nickm@torproject.org>
Date: Wed, 15 May 2019 00:05:53 +0000 (-0400)
Subject: Testing: allow the user to pass a seed in for reproducible-RNG tests
X-Git-Tag: tor-0.4.1.2-alpha~33^2~3
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=72e9c427b81a1d31f28c8398f516fa7892200ef3;p=thirdparty%2Ftor.git

Testing: allow the user to pass a seed in for reproducible-RNG tests

The environment variable TOR_TEST_RNG_SEED, if provided, is a hex
value for the RNG seed.
---

diff --git a/src/test/rng_test_helpers.c b/src/test/rng_test_helpers.c
index c4243f5e9a..1ee2672302 100644
--- a/src/test/rng_test_helpers.c
+++ b/src/test/rng_test_helpers.c
@@ -124,9 +124,22 @@ enable_deterministic_rng_impl(const uint8_t *seed, size_t seed_len)
 void
 testing_enable_reproducible_rng(void)
 {
-  uint8_t seed[16];
-  crypto_rand((char*)seed, sizeof(seed));
-  enable_deterministic_rng_impl(seed, sizeof(seed));
+  const char *provided_seed = getenv("TOR_TEST_RNG_SEED");
+  if (provided_seed) {
+    size_t hexlen = strlen(provided_seed);
+    size_t seedlen = hexlen / 2;
+    uint8_t *seed = tor_malloc(hexlen / 2);
+    if (base16_decode((char*)seed, seedlen, provided_seed, hexlen) < 0) {
+      puts("Cannot decode value in TOR_TEST_RNG_SEED");
+      exit(1);
+    }
+    enable_deterministic_rng_impl(seed, seedlen);
+    tor_free(seed);
+  } else {
+    uint8_t seed[16];
+    crypto_rand((char*)seed, sizeof(seed));
+    enable_deterministic_rng_impl(seed, sizeof(seed));
+  }
 }
 
 /**