Add test for generating safeprime DH parameters

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from #19635)

test/evp_extra_test2.c

@@ -356,6 +356,30 @@ static int test_dh_tofrom_data_select(void)
     EVP_PKEY_CTX_free(gctx);
     return ret;
 }
+
+static int test_dh_paramgen(void)
+{
+    int ret;
+    OSSL_PARAM params[3];
+    EVP_PKEY *pkey = NULL;
+    EVP_PKEY_CTX *gctx = NULL;
+    unsigned int pbits = 512; /* minimum allowed for speed */
+
+    params[0] = OSSL_PARAM_construct_uint(OSSL_PKEY_PARAM_FFC_PBITS, &pbits);
+    params[1] = OSSL_PARAM_construct_utf8_string(OSSL_PKEY_PARAM_FFC_TYPE,
+                                                 "generator", 0);
+    params[2] = OSSL_PARAM_construct_end();
+
+    ret = TEST_ptr(gctx = EVP_PKEY_CTX_new_from_name(mainctx, "DH", NULL))
+          && TEST_int_gt(EVP_PKEY_paramgen_init(gctx), 0)
+          && TEST_true(EVP_PKEY_CTX_set_params(gctx, params))
+          && TEST_true(EVP_PKEY_paramgen(gctx, &pkey))
+          && TEST_ptr(pkey);
+
+    EVP_PKEY_CTX_free(gctx);
+    EVP_PKEY_free(pkey);
+    return ret;
+}
 #endif
 
 #ifndef OPENSSL_NO_EC
@@ -1156,6 +1180,7 @@ int setup_tests(void)
 #endif
 #ifndef OPENSSL_NO_DH
     ADD_TEST(test_dh_tofrom_data_select);
+    ADD_TEST(test_dh_paramgen);
 #endif
     ADD_TEST(test_rsa_tofrom_data_select);