tlsexttest: check additional logic in tlsext randomization

This verifies that we put PSK always last and that the Apache 2 special
does what it is supposed to do. There is also some weak validation of
the Fisher-Yates shuffle that will likely catch errors introduced in
tlsext_randomize_build_order()

1 files changed, 103 insertions, 1 deletions

diff --git a/src/regress/lib/libssl/tlsext/tlsexttest.c b/src/regress/lib/libssl/tlsext/tlsexttest.c
index f5241c8f62..2da1b6487b 100644
--- a/src/regress/lib/libssl/tlsext/tlsexttest.c
+++ b/src/regress/lib/libssl/tlsext/tlsexttest.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: tlsexttest.c,v 1.80 2023/04/23 18:59:41 tb Exp $ */
+/* $OpenBSD: tlsexttest.c,v 1.81 2023/04/27 10:53:58 tb Exp $ */
 /*
  * Copyright (c) 2017 Joel Sing <jsing@openbsd.org>
  * Copyright (c) 2017 Doug Hogan <doug@openbsd.org>
@@ -33,6 +33,7 @@ struct tls_extension_funcs {
         int (*parse)(SSL *s, uint16_t msg_type, CBS *cbs, int *alert);
 };
 
+uint16_t tls_extension_type(const struct tls_extension *);
 const struct tls_extension *tls_extension_find(uint16_t, size_t *);
 const struct tls_extension_funcs *tlsext_funcs(const struct tls_extension *,
     int);
@@ -4442,6 +4443,105 @@ test_tlsext_valid_hostnames(void)
         return failure;
 }
 
+#define N_TLSEXT_RANDOMIZATION_TESTS 1000
+
+static int
+test_tlsext_check_extension_order(SSL *ssl)
+{
+        const struct tls_extension *ext;
+        uint16_t type;
+        size_t alpn_idx, sni_idx;
+        size_t i;
+
+        if (ssl->tlsext_build_order_len == 0) {
+                FAIL("Unexpected zero build order length");
+                return 1;
+        }
+
+        ext = ssl->tlsext_build_order[ssl->tlsext_build_order_len - 1];
+        if ((type = tls_extension_type(ext)) != TLSEXT_TYPE_psk) {
+                FAIL("last extension is %u, want %u\n", type, TLSEXT_TYPE_psk);
+                return 1;
+        }
+
+        if (ssl->server)
+                return 0;
+
+        alpn_idx = sni_idx = ssl->tlsext_build_order_len;
+        for (i = 0; i < ssl->tlsext_build_order_len; i++) {
+                ext = ssl->tlsext_build_order[i];
+                if (tls_extension_type(ext) == TLSEXT_TYPE_alpn)
+                        alpn_idx = i;
+                if (tls_extension_type(ext) == TLSEXT_TYPE_server_name)
+                        sni_idx = i;
+        }
+
+        if (alpn_idx == ssl->tlsext_build_order_len) {
+                FAIL("could not find alpn extension\n");
+                return 1;
+        }
+
+        if (sni_idx == ssl->tlsext_build_order_len) {
+                FAIL("could not find alpn extension\n");
+                return 1;
+        }
+
+        if (sni_idx >= alpn_idx) {
+                FAIL("sni does not precede alpn: %zu >= %zu\n",
+                    sni_idx, alpn_idx);
+                return 1;
+        }
+
+        return 0;
+}
+
+static int
+test_tlsext_randomized_extensions(SSL *ssl)
+{
+        size_t i;
+        int failed = 0;
+
+        for (i = 0; i < N_TLSEXT_RANDOMIZATION_TESTS; i++) {
+                if (!tlsext_randomize_build_order(ssl))
+                        errx(1, "failed to randomize extensions");
+                failed |= test_tlsext_check_extension_order(ssl);
+        }
+
+        return failed;
+}
+
+static int
+test_tlsext_extension_order(void)
+{
+        SSL_CTX *ssl_ctx = NULL;
+        SSL *ssl = NULL;
+        int failure;
+
+        failure = 0;
+
+        if ((ssl_ctx = SSL_CTX_new(TLS_client_method())) == NULL)
+                errx(1, "failed to create SSL_CTX");
+        if ((ssl = SSL_new(ssl_ctx)) == NULL)
+                errx(1, "failed to create SSL");
+
+        failure |= test_tlsext_randomized_extensions(ssl);
+
+        SSL_CTX_free(ssl_ctx);
+        SSL_free(ssl);
+
+        if ((ssl_ctx = SSL_CTX_new(TLS_server_method())) == NULL)
+                errx(1, "failed to create SSL_CTX");
+        if ((ssl = SSL_new(ssl_ctx)) == NULL)
+                errx(1, "failed to create SSL");
+
+        failure |= test_tlsext_randomized_extensions(ssl);
+
+        SSL_CTX_free(ssl_ctx);
+        SSL_free(ssl);
+
+        return failure;
+}
+
 int
 main(int argc, char **argv)
 {
@@ -4500,5 +4600,7 @@ main(int argc, char **argv)
         failed |= test_tlsext_quic_transport_parameters_client();
         failed |= test_tlsext_quic_transport_parameters_server();
 
+        failed |= test_tlsext_extension_order();
+
         return (failed);
 }