1 files changed, 117 insertions, 0 deletions
diff --git a/lib/ext/cookie.c b/lib/ext/cookie.c
new file mode 100644
index 0000000..b4608f3
--- /dev/null
+++ b/lib/ext/cookie.c
@@ -0,0 +1,117 @@
+/*
+ * Copyright (C) 2017 Red Hat, Inc.
+ *
+ * Author: Nikos Mavrogiannopoulos
+ *
+ * This file is part of GnuTLS.
+ *
+ * The GnuTLS is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either version 2.1 of
+ * the License, or (at your option) any later version.
+ *
+ * This library 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
+ * Lesser 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 <https://www.gnu.org/licenses/>
+ *
+ */
+
+/* This file contains the code for the Max Record Size TLS extension.
+ */
+
+#include "gnutls_int.h"
+#include "errors.h"
+#include "num.h"
+#include "hello_ext_lib.h"
+#include <ext/cookie.h>
+
+static int cookie_recv_params(gnutls_session_t session,
+					  const uint8_t * data,
+					  size_t data_size);
+static int cookie_send_params(gnutls_session_t session,
+					  gnutls_buffer_st * extdata);
+
+const hello_ext_entry_st ext_mod_cookie = {
+	.name = "Cookie",
+	.tls_id = 44,
+	.gid = GNUTLS_EXTENSION_COOKIE,
+	.validity = GNUTLS_EXT_FLAG_TLS | GNUTLS_EXT_FLAG_CLIENT_HELLO |
+		    GNUTLS_EXT_FLAG_HRR | GNUTLS_EXT_FLAG_IGNORE_CLIENT_REQUEST,
+	.client_parse_point = GNUTLS_EXT_MANDATORY, /* force parsing prior to EXT_TLS extensions */
+	.server_parse_point = GNUTLS_EXT_MANDATORY, /* force parsing prior to EXT_TLS extensions */
+	.recv_func = cookie_recv_params,
+	.send_func = cookie_send_params,
+	.pack_func = NULL,
+	.unpack_func = NULL,
+	.deinit_func = _gnutls_hello_ext_default_deinit,
+	.cannot_be_overriden = 0
+};
+
+/* Only client sends this extension. */
+static int
+cookie_recv_params(gnutls_session_t session,
+		   const uint8_t * data, size_t data_size)
+{
+	size_t csize;
+	int ret;
+	gnutls_datum_t tmp;
+
+	if (session->security_parameters.entity == GNUTLS_SERVER) {
+		/* we don't support it */
+		return 0;
+	} else { /* client */
+		if (_gnutls_ext_get_msg(session) == GNUTLS_EXT_FLAG_HRR) {
+			DECR_LEN(data_size, 2);
+
+			csize = _gnutls_read_uint16(data);
+			data += 2;
+
+			DECR_LEN(data_size, csize);
+
+			if (data_size != 0)
+				return gnutls_assert_val(GNUTLS_E_UNEXPECTED_PACKET_LENGTH);
+
+			tmp.data = (void*)data;
+			tmp.size = csize;
+
+			ret = _gnutls_hello_ext_set_datum(session, GNUTLS_EXTENSION_COOKIE, &tmp);
+			if (ret < 0)
+				return gnutls_assert_val(ret);
+
+			return 0;
+		}
+
+		return gnutls_assert_val(GNUTLS_E_RECEIVED_ILLEGAL_EXTENSION);
+	}
+
+	return 0;
+}
+
+/* returns data_size or a negative number on failure
+ */
+static int
+cookie_send_params(gnutls_session_t session,
+		   gnutls_buffer_st * extdata)
+{
+	gnutls_datum_t tmp;
+	int ret;
+
+	/* this function sends the client extension data (dnsname) */
+	if (session->security_parameters.entity == GNUTLS_CLIENT) {
+		ret = _gnutls_hello_ext_get_datum(session, GNUTLS_EXTENSION_COOKIE, &tmp);
+		if (ret < 0)
+			return 0;
+
+		ret = _gnutls_buffer_append_data_prefix(extdata, 16, tmp.data, tmp.size);
+		if (ret < 0)
+			return gnutls_assert_val(ret);
+
+		return 0;
+	}
+
+	return 0;
+}