Add some SSL BIO tests

This adds some simple SSL BIO tests that check for pushing and popping of
BIOs into the chain. These tests would have caught the bugs fixed in the
previous three commits, if combined with a crypto-mdebug build.
Reviewed-by: NRich Salz <rsalz@openssl.org>

test/sslapitest.c

@@ -441,6 +441,123 @@ static int test_ssl_set_bio(int idx)
     return testresult;
 }
 
+typedef struct ssl_bio_test_fixture {
+    const char *test_case_name;
+    int pop_ssl;
+    enum { NO_BIO_CHANGE, CHANGE_RBIO, CHANGE_WBIO } change_bio;
+} SSL_BIO_TEST_FIXTURE;
+
+static SSL_BIO_TEST_FIXTURE ssl_bio_set_up(const char *const test_case_name)
+{
+    SSL_BIO_TEST_FIXTURE fixture;
+
+    fixture.test_case_name = test_case_name;
+    fixture.pop_ssl = 0;
+
+    return fixture;
+}
+
+static void ssl_bio_tear_down(SSL_BIO_TEST_FIXTURE fixture)
+{
+}
+
+static int execute_test_ssl_bio(SSL_BIO_TEST_FIXTURE fix)
+{
+    BIO *sslbio = NULL, *membio1 = NULL, *membio2 = NULL;
+    SSL_CTX *ctx = SSL_CTX_new(TLS_method());
+    SSL *ssl = NULL;
+    int testresult = 0;
+
+    if (ctx == NULL) {
+        printf("Failed to allocate SSL_CTX\n");
+        return 0;
+    }
+
+    ssl = SSL_new(ctx);
+    if (ssl == NULL) {
+        printf("Failed to allocate SSL object\n");
+        goto end;
+    }
+
+    sslbio = BIO_new(BIO_f_ssl());
+    membio1 = BIO_new(BIO_s_mem());
+
+    if (sslbio == NULL || membio1 == NULL) {
+        printf("Malloc failure creating BIOs\n");
+        goto end;
+    }
+
+    BIO_set_ssl(sslbio, ssl, BIO_CLOSE);
+
+    /*
+     * If anything goes wrong here then we could leak memory, so this will
+     * be caught in a crypto-mdebug build
+     */
+    BIO_push(sslbio, membio1);
+
+    /* Verify chaning the rbio/wbio directly does not cause leaks */
+    if (fix.change_bio != NO_BIO_CHANGE) {
+        membio2 = BIO_new(BIO_s_mem());
+        if (membio2 == NULL) {
+            printf("Malloc failure creating membio2\n");
+            goto end;
+        }
+        if (fix.change_bio == CHANGE_RBIO)
+            SSL_set_rbio(ssl, membio2);
+        else
+            SSL_set_wbio(ssl, membio2);
+    }
+    ssl = NULL;
+
+    if (fix.pop_ssl)
+        BIO_pop(sslbio);
+    else
+        BIO_pop(membio1);
+
+    testresult = 1;
+ end:
+    BIO_free(membio1);
+    BIO_free(sslbio);
+    SSL_free(ssl);
+    SSL_CTX_free(ctx);
+
+    return testresult;
+}
+
+static int test_ssl_bio_pop_next_bio(void)
+{
+    SETUP_TEST_FIXTURE(SSL_BIO_TEST_FIXTURE, ssl_bio_set_up);
+
+    EXECUTE_TEST(execute_test_ssl_bio, ssl_bio_tear_down);
+}
+
+static int test_ssl_bio_pop_ssl_bio(void)
+{
+    SETUP_TEST_FIXTURE(SSL_BIO_TEST_FIXTURE, ssl_bio_set_up);
+
+    fixture.pop_ssl = 1;
+
+    EXECUTE_TEST(execute_test_ssl_bio, ssl_bio_tear_down);
+}
+
+static int test_ssl_bio_change_rbio(void)
+{
+    SETUP_TEST_FIXTURE(SSL_BIO_TEST_FIXTURE, ssl_bio_set_up);
+
+    fixture.change_bio = CHANGE_RBIO;
+
+    EXECUTE_TEST(execute_test_ssl_bio, ssl_bio_tear_down);
+}
+
+static int test_ssl_bio_change_wbio(void)
+{
+    SETUP_TEST_FIXTURE(SSL_BIO_TEST_FIXTURE, ssl_bio_set_up);
+
+    fixture.change_bio = CHANGE_WBIO;
+
+    EXECUTE_TEST(execute_test_ssl_bio, ssl_bio_tear_down);
+}
+
 int main(int argc, char *argv[])
 {
     BIO *err = NULL;
@@ -464,6 +581,10 @@ int main(int argc, char *argv[])
     ADD_TEST(test_session_with_only_ext_cache);
     ADD_TEST(test_session_with_both_cache);
     ADD_ALL_TESTS(test_ssl_set_bio, TOTAL_SSL_SET_BIO_TESTS);
+    ADD_TEST(test_ssl_bio_pop_next_bio);
+    ADD_TEST(test_ssl_bio_pop_ssl_bio);
+    ADD_TEST(test_ssl_bio_change_rbio);
+    ADD_TEST(test_ssl_bio_change_wbio);
 
     testresult = run_tests(argv[0]);