[glib-networking/mcatanzaro/#20: 16/18] gnutls: account for internal TLS buffer in check function

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 4dbb780f40f5b1dfb0159acb697b48e2e4acce26
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Sun Jan 26 14:33:09 2020 -0600

    gnutls: account for internal TLS buffer in check function
    
    If the GnuTLS buffer has readable data, then we must report that we are
    readable, or applications could stall forever waiting to read the data
    that is already present.
    
    Fixes #20

 tls/base/gtlsconnection-base.c     | 10 ++++++++++
 tls/base/gtlsconnection-base.h     |  3 +++
 tls/gnutls/gtlsconnection-gnutls.c | 14 ++++++++++++++
 3 files changed, 27 insertions(+)
---
diff --git a/tls/base/gtlsconnection-base.c b/tls/base/gtlsconnection-base.c
index 5d8ab2b4..e184552d 100644
--- a/tls/base/gtlsconnection-base.c
+++ b/tls/base/gtlsconnection-base.c
@@ -921,6 +921,16 @@ g_tls_connection_base_check (GTlsConnectionBase  *tls,
       ((condition & G_IO_OUT) && (priv->writing || priv->write_closing)))
     goto out;
 
+  /* If base class says we are ready, then we are, regardless of the base
+   * stream status. This accounts for TLS-level buffers.
+   */
+  if (G_TLS_CONNECTION_BASE_GET_CLASS (tls)->check &&
+      G_TLS_CONNECTION_BASE_GET_CLASS (tls)->check (tls, condition))
+    {
+      ret = TRUE;
+      goto out;
+    }
+
   /* Defer to the base stream or GDatagramBased. */
   ret = g_tls_connection_base_base_check (tls, condition);
 
diff --git a/tls/base/gtlsconnection-base.h b/tls/base/gtlsconnection-base.h
index 45c14e52..86425023 100644
--- a/tls/base/gtlsconnection-base.h
+++ b/tls/base/gtlsconnection-base.h
@@ -79,6 +79,9 @@ struct _GTlsConnectionBaseClass
 
   gboolean                    (*is_session_resumed)         (GTlsConnectionBase   *tls);
 
+  gboolean                    (*check)                      (GTlsConnectionBase   *tls,
+                                                             GIOCondition          direction);
+
   void                        (*push_io)                    (GTlsConnectionBase   *tls,
                                                              GIOCondition          direction,
                                                              gint64                timeout,
diff --git a/tls/gnutls/gtlsconnection-gnutls.c b/tls/gnutls/gtlsconnection-gnutls.c
index 1e099574..3aab9e43 100644
--- a/tls/gnutls/gtlsconnection-gnutls.c
+++ b/tls/gnutls/gtlsconnection-gnutls.c
@@ -848,6 +848,19 @@ g_tls_connection_gnutls_is_session_resumed (GTlsConnectionBase *tls)
   return gnutls_session_is_resumed (priv->session);
 }
 
+static gboolean
+g_tls_connection_gnutls_check (GTlsConnectionBase *tls,
+                               GIOCondition        direction)
+{
+  GTlsConnectionGnutls *gnutls = G_TLS_CONNECTION_GNUTLS (tls);
+  GTlsConnectionGnutlsPrivate *priv = g_tls_connection_gnutls_get_instance_private (gnutls);
+
+  if (direction & G_IO_IN)
+    return !!gnutls_record_check_pending (priv->session);
+
+  return FALSE;
+}
+
 static GTlsConnectionBaseStatus
 g_tls_connection_gnutls_read (GTlsConnectionBase  *tls,
                               void                *buffer,
@@ -1071,6 +1084,7 @@ g_tls_connection_gnutls_class_init (GTlsConnectionGnutlsClass *klass)
   base_class->retrieve_peer_certificate                  = g_tls_connection_gnutls_retrieve_peer_certificate;
   base_class->complete_handshake                         = g_tls_connection_gnutls_complete_handshake;
   base_class->is_session_resumed                         = g_tls_connection_gnutls_is_session_resumed;
+  base_class->check                                      = g_tls_connection_gnutls_check;
   base_class->read_fn                                    = g_tls_connection_gnutls_read;
   base_class->read_message_fn                            = g_tls_connection_gnutls_read_message;
   base_class->write_fn                                   = g_tls_connection_gnutls_write;