1 files changed, 18 insertions, 0 deletions
diff --git a/src/or/main.c b/src/or/main.c
index ce0d6bce75..b9fd747360 100644
--- a/src/or/main.c
+++ b/src/or/main.c
@@ -29,6 +29,7 @@ static void signal_callback(int fd, short events, void *arg);
 static void second_elapsed_callback(int fd, short event, void *args);
 static int conn_close_if_marked(int i);
 static void connection_start_reading_from_linked_conn(connection_t *conn);
+static int connection_should_read_from_linked_conn(connection_t *conn);
 
 /********* START VARIABLES **********/
 
@@ -399,6 +400,23 @@ connection_start_writing(connection_t *conn)
   }
 }
 
+/** Return true iff <b>conn</b> is linked conn, and reading from the conn
+ * linked to it would be good and feasible.  (Reading is "feasible" if the
+ * other conn exists and has data in its outbuf, and is "good" if we have our
+ * reading_from_linked_conn flag set and the other conn has its
+ * writing_to_linked_conn flag set.)*/
+static int
+connection_should_read_from_linked_conn(connection_t *conn)
+{
+  if (conn->linked && conn->reading_from_linked_conn) {
+    if (! conn->linked_conn ||
+        (conn->linked_conn->writing_to_linked_conn &&
+         buf_datalen(conn->linked_conn->outbuf)))
+      return 1;
+  }
+  return 0;
+}
+
 /** Helper: Tell the main loop to begin reading bytes into <b>conn</b> from
  * its linked connection, if it is not doing so already.  Called by
  * connection_start_reading and connection_start_writing as appropriate. */