[glib-networking] Never accept a missing certificate

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 1ba8c0bffbc27605d7188c16f71a0964d6b49f6f
Author: Michael Catanzaro <mcatanzaro igalia com>
Date:   Sun Nov 11 21:01:21 2018 -0600

    Never accept a missing certificate
    
    If the server doesn't send a certificate, we should wind up failing with
    GNUTLS_E_NO_CIPHER_SUITES. Still, let's explicitly check to make sure
    it's here, just in case.

 tls/gnutls/gtlsconnection-gnutls.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/tls/gnutls/gtlsconnection-gnutls.c b/tls/gnutls/gtlsconnection-gnutls.c
index 3e1b5a3..3200079 100644
--- a/tls/gnutls/gtlsconnection-gnutls.c
+++ b/tls/gnutls/gtlsconnection-gnutls.c
@@ -1825,7 +1825,7 @@ accept_peer_certificate (GTlsConnectionGnutls *gnutls,
 
   g_assert (g_main_context_is_owner (priv->handshake_context));
 
-  if (G_IS_TLS_CLIENT_CONNECTION (gnutls))
+  if (G_IS_TLS_CLIENT_CONNECTION (gnutls) && priv->peer_certificate != NULL)
     {
       GTlsCertificateFlags validation_flags;