Ensure we are sending the right protocol version on second client hello

That is, when we respond to a Hello Retry Request as client, we put
the TLS1.2 version on the second client hello to send a hello that is
as close as possible to the original hello. That effectively separates
the handling of TLS1.2 rehandshake and TLS1.3 hello retry request
when sending a client hello.

Resolves #535

Signed-off-by: Nikos Mavrogiannopoulos <nmav@redhat.com>

3 files changed, 242 insertions, 4 deletions

diff --git a/lib/handshake.c b/lib/handshake.c
index 7274bafebd..2c7524016e 100644
--- a/lib/handshake.c
+++ b/lib/handshake.c
@@ -1991,12 +1991,13 @@ static int send_client_hello(gnutls_session_t session, int again)
 	uint8_t session_id_len =
 	    session->internals.resumed_security_parameters.session_id_size;
 
-	/* note that rehandshake is different than resuming
-	 */
-	if (session->security_parameters.session_id_size)
-		rehandshake = 1;
 
 	if (again == 0) {
+		/* note that rehandshake is different than resuming
+		 */
+		if (session->internals.initial_negotiation_completed)
+			rehandshake = 1;
+
 		ret = _gnutls_buffer_init_handshake_mbuffer(&extdata);
 		if (ret < 0)
 			return gnutls_assert_val(ret);
diff --git a/tests/Makefile.am b/tests/Makefile.am
index c9f62f16f0..87da31a25d 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -109,6 +109,8 @@ ctests = tls13/supported_versions tls13/tls12-no-tls13-exts \
 	tls12-check-rollback-val tls11-check-rollback-val tls13/hello_random_value \
 	tls13/post-handshake-with-psk
 
+ctests += tls13/hello_retry_request
+
 ctests += tls13/psk-ext
 
 ctests += tls13/key_update
diff --git a/tests/tls13/hello_retry_request.c b/tests/tls13/hello_retry_request.c
new file mode 100644
index 0000000000..66e4701e3a
--- /dev/null
+++ b/tests/tls13/hello_retry_request.c
@@ -0,0 +1,235 @@
+/*
+ * Copyright (C) 2017-2018 Red Hat, Inc.
+ *
+ * Author: Nikos Mavrogiannopoulos
+ *
+ * This file is part of GnuTLS.
+ *
+ * GnuTLS is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuTLS is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#if defined(_WIN32)
+
+int main()
+{
+	exit(77);
+}
+
+#else
+
+#include <string.h>
+#include <sys/types.h>
+#include <netinet/in.h>
+#include <sys/socket.h>
+#include <sys/wait.h>
+#include <arpa/inet.h>
+#include <unistd.h>
+#include <gnutls/gnutls.h>
+#include <gnutls/dtls.h>
+#include <assert.h>
+#include <signal.h>
+
+#include "cert-common.h"
+#include "utils.h"
+#include "tls13/ext-parse.h"
+
+/* This program tests whether the version in Hello Retry Request message
+ * is the expected */
+
+const char *testname = "";
+
+#define myfail(fmt, ...) \
+	fail("%s: "fmt, testname, ##__VA_ARGS__)
+
+static void server_log_func(int level, const char *str)
+{
+	fprintf(stderr, "server|<%d>| %s", level, str);
+}
+
+static void client_log_func(int level, const char *str)
+{
+	fprintf(stderr, "client|<%d>| %s", level, str);
+}
+
+struct ctx_st {
+	unsigned hrr_seen;
+	unsigned hello_counter;
+};
+
+static int hello_callback(gnutls_session_t session, unsigned int htype,
+			  unsigned post, unsigned int incoming, const gnutls_datum_t *msg)
+{
+	struct ctx_st *ctx = gnutls_session_get_ptr(session);
+	assert(ctx != NULL);
+
+	if (htype == GNUTLS_HANDSHAKE_HELLO_RETRY_REQUEST)
+		ctx->hrr_seen = 1;
+
+	if (htype == GNUTLS_HANDSHAKE_CLIENT_HELLO && post == GNUTLS_HOOK_POST) {
+		if (ctx->hello_counter > 0) {
+			assert(msg->size > 4);
+			if (msg->data[0] != 0x03 || msg->data[1] != 0x03) {
+				fail("version is %d.%d expected 3,3\n", (int)msg->data[0], (int)msg->data[1]);
+			}
+		}
+		ctx->hello_counter++;
+	}
+
+	return 0;
+}
+
+
+static void client(int fd)
+{
+	int ret;
+	gnutls_certificate_credentials_t x509_cred;
+	gnutls_session_t session;
+	struct ctx_st ctx;
+
+	memset(&ctx, 0, sizeof(ctx));
+
+	if (debug) {
+		gnutls_global_set_log_function(client_log_func);
+		gnutls_global_set_log_level(7);
+	}
+
+	assert(gnutls_certificate_allocate_credentials(&x509_cred)>=0);
+
+	assert(gnutls_init(&session, GNUTLS_CLIENT|GNUTLS_KEY_SHARE_TOP)>=0);
+
+	gnutls_handshake_set_timeout(session, 20 * 1000);
+	gnutls_session_set_ptr(session, &ctx);
+
+	ret = gnutls_priority_set_direct(session, "NORMAL:-VERS-ALL:+VERS-TLS1.3:-GROUP-ALL:+GROUP-SECP256R1:+GROUP-X25519", NULL);
+	if (ret < 0)
+		myfail("cannot set TLS 1.3 priorities\n");
+
+	gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
+
+	gnutls_handshake_set_hook_function(session, GNUTLS_HANDSHAKE_ANY,
+					   GNUTLS_HOOK_BOTH,
+					   hello_callback);
+
+	gnutls_transport_set_int(session, fd);
+
+	do {
+		ret = gnutls_handshake(session);
+	}
+	while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
+
+	assert(ctx.hrr_seen != 0);
+
+	close(fd);
+
+	gnutls_deinit(session);
+
+	gnutls_certificate_free_credentials(x509_cred);
+}
+
+static void server(int fd)
+{
+	int ret;
+	gnutls_session_t session;
+	gnutls_certificate_credentials_t x509_cred;
+
+	if (debug) {
+		gnutls_global_set_log_function(server_log_func);
+		gnutls_global_set_log_level(4711);
+	}
+
+	assert(gnutls_certificate_allocate_credentials(&x509_cred)>=0);
+	assert(gnutls_certificate_set_x509_key_mem(x509_cred, &server_cert,
+						   &server_key,
+						   GNUTLS_X509_FMT_PEM)>=0);
+
+	gnutls_init(&session, GNUTLS_SERVER);
+
+	gnutls_handshake_set_timeout(session, 20 * 1000);
+
+	/* server only supports x25519, client advertises secp256r1 */
+	assert(gnutls_priority_set_direct(session, "NORMAL:-VERS-ALL:+VERS-TLS1.3:-GROUP-ALL:+GROUP-X25519", NULL)>=0);
+
+	gnutls_credentials_set(session, GNUTLS_CRD_CERTIFICATE, x509_cred);
+
+	gnutls_transport_set_int(session, fd);
+
+	do {
+		ret = gnutls_handshake(session);
+		if (ret == GNUTLS_E_INTERRUPTED) { /* expected */
+			break;
+		}
+	} while (ret < 0 && gnutls_error_is_fatal(ret) == 0);
+
+	if (ret < 0)
+		myfail("handshake error: %s\n", gnutls_strerror(ret));
+
+	if (gnutls_group_get(session) != GNUTLS_GROUP_X25519)
+		myfail("group doesn't match the expected: %s\n", gnutls_group_get_name(gnutls_group_get(session)));
+
+	close(fd);
+	gnutls_deinit(session);
+
+	gnutls_certificate_free_credentials(x509_cred);
+}
+
+static void ch_handler(int sig)
+{
+	int status = 0;
+	wait(&status);
+	check_wait_status(status);
+	return;
+}
+
+void doit(void)
+{
+	int fd[2];
+	int ret;
+	pid_t child;
+
+	signal(SIGCHLD, ch_handler);
+	signal(SIGPIPE, SIG_IGN);
+
+	ret = socketpair(AF_UNIX, SOCK_STREAM, 0, fd);
+	if (ret < 0) {
+		perror("socketpair");
+		exit(1);
+	}
+
+	child = fork();
+	if (child < 0) {
+		perror("fork");
+		fail("fork");
+		exit(1);
+	}
+
+	if (child) {
+		/* parent */
+		close(fd[1]);
+		client(fd[0]);
+		kill(child, SIGTERM);
+	} else {
+		close(fd[0]);
+		server(fd[1]);
+		exit(0);
+	}
+}
+
+#endif				/* _WIN32 */