[glib-networking/mcatanzaro/channel-bindings-take-two: 3/4] gnutls: use new GnuTLS channel binding implementations when possible

[Michael Catanzaro <mcatanzaro src gnome org>]

commit a566ceff521ad91bd0f7d6fd5615aa9b4eedc9e8
Author: Michael Catanzaro <mcatanzaro redhat com>
Date:   Tue Jun 22 20:17:04 2021 -0500

    gnutls: use new GnuTLS channel binding implementations when possible
    
    Ruslan has landed support for the server endpoint and exporter channel
    binding types in GnuTLS, so let's depend on that if available. We can
    retain his original implementations as fallback until GnuTLS 3.7 is
    stable.

 tls/gnutls/gtlsconnection-gnutls.c | 34 +++++++++++++++++++++++++++-------
 1 file changed, 27 insertions(+), 7 deletions(-)
---
diff --git a/tls/gnutls/gtlsconnection-gnutls.c b/tls/gnutls/gtlsconnection-gnutls.c
index f99ba40..c385a37 100644
--- a/tls/gnutls/gtlsconnection-gnutls.c
+++ b/tls/gnutls/gtlsconnection-gnutls.c
@@ -929,19 +929,20 @@ g_tls_connection_gnutls_is_session_resumed (GTlsConnectionBase *tls)
 }
 
 static gboolean
-gnutls_get_binding_tls_unique (GTlsConnectionGnutls  *gnutls,
-                               GByteArray            *data,
-                               GError               **error)
+gnutls_get_binding (GTlsConnectionGnutls      *gnutls,
+                    GByteArray                *data,
+                    gnutls_channel_binding_t   binding,
+                    GError                   **error)
 {
   GTlsConnectionGnutlsPrivate *priv = g_tls_connection_gnutls_get_instance_private (gnutls);
   gnutls_datum_t cb;
-  int ret = gnutls_session_channel_binding (priv->session, GNUTLS_CB_TLS_UNIQUE, &cb);
+  int ret = gnutls_session_channel_binding (priv->session, binding, &cb);
 
   if (ret == GNUTLS_E_SUCCESS)
     {
       if (data != NULL)
         {
-          g_tls_log_debug (gnutls, "tls-unique binding size %d", cb.size);
+          g_tls_log_debug (gnutls, "binding size %d", cb.size);
           g_free (g_byte_array_steal (data, NULL));
           g_byte_array_append (data, cb.data, cb.size);
         }
@@ -953,11 +954,11 @@ gnutls_get_binding_tls_unique (GTlsConnectionGnutls  *gnutls,
     {
     case GNUTLS_E_UNIMPLEMENTED_FEATURE:
       g_set_error (error, G_TLS_CHANNEL_BINDING_ERROR, G_TLS_CHANNEL_BINDING_ERROR_NOT_IMPLEMENTED,
-                   _("Channel binding type tls-unique is not implemented in the TLS library"));
+                   _("Channel binding type is not implemented in the TLS library"));
       break;
     case GNUTLS_E_CHANNEL_BINDING_NOT_AVAILABLE:
       g_set_error (error, G_TLS_CHANNEL_BINDING_ERROR, G_TLS_CHANNEL_BINDING_ERROR_NOT_AVAILABLE,
-                   _("Channel binding data for tls-unique is not yet available"));
+                   _("Channel binding data is not yet available"));
       break;
     default:
       g_set_error (error, G_TLS_CHANNEL_BINDING_ERROR, G_TLS_CHANNEL_BINDING_ERROR_GENERAL_ERROR,
@@ -966,11 +967,22 @@ gnutls_get_binding_tls_unique (GTlsConnectionGnutls  *gnutls,
   return FALSE;
 }
 
+static gboolean
+gnutls_get_binding_tls_unique (GTlsConnectionGnutls  *gnutls,
+                               GByteArray            *data,
+                               GError               **error)
+{
+  return gnutls_get_binding (gnutls, data, GNUTLS_CB_TLS_UNIQUE, error);
+}
+
 static gboolean
 gnutls_get_binding_tls_server_end_point (GTlsConnectionGnutls  *gnutls,
                                          GByteArray            *data,
                                          GError               **error)
 {
+#if GNUTLS_VERSION_MAJOR > 3 || GNUTLS_VERSION_MAJOR == 3 && GNUTLS_VERSION_MINOR >= 7
+  return gnutls_get_binding (gnutls, data, GNUTLS_CB_TLS_SERVER_END_POINT, error);
+#else
   GTlsConnectionGnutlsPrivate *priv = g_tls_connection_gnutls_get_instance_private (gnutls);
   const gnutls_datum_t *ders;
   unsigned int num_certs = 1;
@@ -1065,10 +1077,14 @@ gnutls_get_binding_tls_server_end_point (GTlsConnectionGnutls  *gnutls,
   g_set_error (error, G_TLS_CHANNEL_BINDING_ERROR, G_TLS_CHANNEL_BINDING_ERROR_GENERAL_ERROR,
                "%s", gnutls_strerror(ret));
   return FALSE;
+#endif
 }
 
+#if !(GNUTLS_VERSION_MAJOR > 3 || GNUTLS_VERSION_MAJOR == 3 && GNUTLS_VERSION_MINOR >= 7)
 #define RFC5705_LABEL_DATA "EXPORTER-Channel-Binding"
 #define RFC5705_LABEL_LEN 24
+#endif
+
 /* Experimental binding for TLS1.3, see
  * https://datatracker.ietf.org/doc/draft-ietf-kitten-tls-channel-bindings-for-tls13 */
 static gboolean
@@ -1076,6 +1092,9 @@ gnutls_get_binding_tls_exporter (GTlsConnectionGnutls  *gnutls,
                                  GByteArray            *data,
                                  GError               **error)
 {
+#if GNUTLS_VERSION_MAJOR > 3 || GNUTLS_VERSION_MAJOR == 3 && GNUTLS_VERSION_MINOR >= 7
+  return gnutls_get_binding (gnutls, data, GNUTLS_CB_TLS_EXPORTER, error);
+#else
   GTlsConnectionGnutlsPrivate *priv = g_tls_connection_gnutls_get_instance_private (gnutls);
   int ret;
   gsize ctx_len = 0;
@@ -1097,6 +1116,7 @@ gnutls_get_binding_tls_exporter (GTlsConnectionGnutls  *gnutls,
   g_set_error (error, G_TLS_CHANNEL_BINDING_ERROR, G_TLS_CHANNEL_BINDING_ERROR_GENERAL_ERROR,
                "%s", gnutls_strerror (ret));
   return FALSE;
+#endif
 }
 
 static gboolean