test: add test for generation of random data in chunks.

THe EVP_RAND wrapper works with the underlying RNG to produce the amount of
random data requested even if it is larger than the largest single generation
the source allows.  This test verified that this works.

Reviewed-by: Matthias St. Pierre <Matthias.St.Pierre@ncp-e.com>
(Merged from https://github.com/openssl/openssl/pull/11682)

1 files changed, 33 insertions, 0 deletions

diff --git a/test/evp_extra_test.c b/test/evp_extra_test.c
index fe139fbf17..1876bdcf11 100644
--- a/test/evp_extra_test.c
+++ b/test/evp_extra_test.c
@@ -1770,6 +1770,37 @@ static int test_pkey_ctx_fail_without_provider(int tst)
     return ret;
 }
 
+static int test_rand_agglomeration(void)
+{
+    EVP_RAND *rand;
+    EVP_RAND_CTX *ctx;
+    OSSL_PARAM params[3], *p = params;
+    int res;
+    unsigned int step = 7;
+    static unsigned char seed[] = "It does not matter how slowly you go "
+                                  "as long as you do not stop.";
+    unsigned char out[sizeof(seed)];
+
+    if (!TEST_int_ne(sizeof(seed) % step, 0)
+            || !TEST_ptr(rand = EVP_RAND_fetch(NULL, "TEST-RAND", NULL)))
+        return 0;
+    ctx = EVP_RAND_CTX_new(rand, NULL);
+    EVP_RAND_free(rand);
+    if (!TEST_ptr(ctx))
+        return 0;
+
+    memset(out, 0, sizeof(out));
+    *p++ = OSSL_PARAM_construct_octet_string(OSSL_RAND_PARAM_TEST_ENTROPY,
+                                             seed, sizeof(seed));
+    *p++ = OSSL_PARAM_construct_uint(OSSL_DRBG_PARAM_MAX_REQUEST, &step);
+    *p = OSSL_PARAM_construct_end();
+    res = TEST_true(EVP_RAND_set_ctx_params(ctx, params))
+          && TEST_true(EVP_RAND_generate(ctx, out, sizeof(out), 0, 1, NULL, 0))
+          && TEST_mem_eq(seed, sizeof(seed), out, sizeof(out));
+    EVP_RAND_CTX_free(ctx);
+    return res;
+}
+
 int setup_tests(void)
 {
     testctx = OPENSSL_CTX_new();
@@ -1823,6 +1854,8 @@ int setup_tests(void)
     ADD_ALL_TESTS(test_keygen_with_empty_template, 2);
     ADD_ALL_TESTS(test_pkey_ctx_fail_without_provider, 2);
 
+    ADD_TEST(test_rand_agglomeration);
+
     return 1;
 }