Added simpler verification functions for clients

The major use-case for the TLS protocol is verification of PKIX
certificates. However, certificate verification support while is
similar for almost all projects it requires around 100 lines of code
(a callback) to be duplicated to all applications. That patch
set gets rid of the callback and simplifies certificate verification
support, by introducing a very simple API; one that would accept
the session and the hostname only.

Resolves #27

1 files changed, 135 insertions, 0 deletions

diff --git a/lib/auto-verify.c b/lib/auto-verify.c
new file mode 100644
index 0000000000..b1d3a1c752
--- /dev/null
+++ b/lib/auto-verify.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (C) 2015 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 <http://www.gnu.org/licenses/>
+ *
+ */
+
+#include "gnutls_int.h"
+#include "errors.h"
+#include <auth/cert.h>
+#include <gnutls/gnutls.h>
+
+/* This file implements the client certificate auto verification functionality.
+ */
+
+/* The actual verification callback. */
+static int auto_verify_cb(gnutls_session_t session)
+{
+        unsigned int status;
+        int ret;
+
+        if (session->internals.vc_elements == 0) {
+        	ret = gnutls_certificate_verify_peers2(session, &status);
+	} else {
+	        ret = gnutls_certificate_verify_peers(session, session->internals.vc_data,
+						      session->internals.vc_elements, &status);
+        }
+        if (ret < 0) {
+                return gnutls_assert_val(GNUTLS_E_CERTIFICATE_ERROR);
+        }
+
+        session->internals.vc_status = status;
+
+        if (status != 0)        /* Certificate is not trusted */
+                return gnutls_assert_val(GNUTLS_E_CERTIFICATE_ERROR);
+
+        /* notify gnutls to continue handshake normally */
+        return 0;
+}
+
+/**
+ * gnutls_session_auto_verify_cert:
+ * @session: is a gnutls session
+ * @hostname: is the expected name of the peer; may be %NULL
+ * @flags: should be zero
+ *
+ * This function instructs GnuTLS to verify the peer's certificate
+ * using the provided hostname. If the verification fails the handshake
+ * will also fail. The verification result can be obtained using
+ * gnutls_session_get_verify_cert_status().
+ *
+ * The hostname pointer provided must remain valid for the lifetime
+ * of the session. If not hostname is provided, no hostname verification
+ * will be performed.
+ *
+ * That function is intended to be used by clients.
+ *
+ * Since: 3.5.0
+ **/
+void gnutls_session_auto_verify_cert(gnutls_session_t session,
+				     const char *hostname, unsigned flags)
+{
+	if (hostname) {
+		session->internals.vc_sdata.type = GNUTLS_DT_DNS_HOSTNAME;
+		session->internals.vc_sdata.data = (void*)hostname;
+		session->internals.vc_sdata.size = 0;
+		session->internals.vc_elements = 1;
+		session->internals.vc_data = &session->internals.vc_sdata;
+	} else {
+		session->internals.vc_elements = 0;
+	}
+
+	gnutls_session_set_verify_function(session, auto_verify_cb);
+}
+
+/**
+ * gnutls_session_auto_verify_cert2:
+ * @session: is a gnutls session
+ * @data: an array of typed data
+ * @elements: the number of data elements
+ * @flags: should be zero
+ *
+ * This function instructs GnuTLS to verify the peer's certificate
+ * using the provided typed data information. If the verification fails the handshake
+ * will also fail. The verification result can be obtained using
+ * gnutls_session_get_verify_cert_status().
+ *
+ * The acceptable typed data are the same as in gnutls_certificate_verify_peers(),
+ * and once set must remain valid for the lifetime of the session.
+ *
+ * Since: 3.5.0
+ **/
+void gnutls_session_auto_verify_cert2(gnutls_session_t session,
+				     gnutls_typed_vdata_st * data,
+				     unsigned elements,
+				     unsigned flags)
+{
+	session->internals.vc_data = data;
+	session->internals.vc_elements = elements;
+	gnutls_session_set_verify_function(session, auto_verify_cb);
+}
+
+/**
+ * gnutls_session_get_verify_cert_status:
+ * @session: is a gnutls session
+ *
+ * This function returns the status of the verification when initiated
+ * via auto-verification, i.e., by gnutls_session_auto_verify_cert2() or
+ * gnutls_session_auto_verify_cert().
+ *
+ * The certificate verification status is the same as in gnutls_certificate_verify_peers().
+ *
+ * Returns: the certificate verification status.
+ *
+ * Since: 3.5.0
+ **/
+unsigned int gnutls_session_get_verify_cert_status(gnutls_session_t session)
+{
+	return session->internals.vc_status;
+}