tests: add negative version negotation tests

tests/include.am

@@ -45,6 +45,7 @@ EXTRA_DIST += tests/unit.h \
               tests/test-dtls-srtp-fails.conf \
               tests/test-dtls13.conf \
               tests/test-dtls13-downgrade.conf \
+              tests/test-dtls13-downgrade-fails.conf \
               tests/test-dtls13-psk.conf \
               tests/test-dtls13-cid.conf \
               tests/test-sctp.conf \

tests/suites.c

@@ -1151,6 +1151,18 @@ int SuiteTest(int argc, char** argv)
         args.return_code = EXIT_FAILURE;
         goto exit;
     }
+    args.argc = 3;
+    strcpy(argv0[1], "tests/test-dtls13-downgrade-fails.conf");
+    strcpy(argv0[2], "expFail");
+    printf("starting DTLSv1.3 suite - downgrade - (expFails)\n");
+    test_harness(&args);
+    if (args.return_code != 0) {
+        printf("error from script %d\n", args.return_code);
+        args.return_code = EXIT_FAILURE;
+        goto exit;
+    }
+    args.argc = 2;
+    XMEMSET(argv0[2], 0, sizeof(argv0[2]));
 #endif /* WOLFSSL_NO_TLS12 */
 
 #ifndef NO_PSK

tests/test-dtls13-downgrade-fails.conf

@@ -0,0 +1,20 @@
+# server DTLSv1.3
+-v4
+-u
+-l TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
+
+# client DTLSv1.2
+-v 3
+-u
+-l TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
+
+# server DTLSv1.3
+-vd
+-7 3
+-u
+-l TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA
+
+# client DTLSv1.0
+-v 2
+-u
+-l TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA