1 files changed, 144 insertions, 0 deletions
diff --git a/bgpd/bgp_engine.c b/bgpd/bgp_engine.c
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+/* BGP Engine pThread -- functions
+ * Copyright (C) 2009 Chris Hall (GMCH), Highwayman
+ *
+ * This file is part of GNU Zebra.
+ *
+ * GNU Zebra is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation; either version 2, or (at your option) any
+ * later version.
+ *
+ * GNU Zebra 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
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with GNU Zebra; see the file COPYING.  If not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include <zebra.h>
+
+#include "bgpd/bgp_engine.h"
+
+#include "lib/memory.h"
+#include "lib/symtab.h"
+
+/*==============================================================================
+ * The BGP Engine pThread contains:
+ *
+ *   * the BGP Finite State Machine (FSM) for BGP Sessions
+ *   * the encoding and decoding of BGP protocol messages
+ *   * all related socket handling and I/O
+ *   * all related timers
+ *
+ * The BGP Engine communicates with the BGP Routeing pthread(s) via two Message
+ * Queues.
+ *
+ * There are also shared pools of data:
+ *
+ *   * the BGP session structures, which ...
+ *   * the Attributes Store
+ *   * the Prefixes Store
+ *   ...
+ *
+ * Other pthread-safe facilities used:
+ *
+ *   * logging
+ *   * privilege raising/lowering
+ *   ...
+ *
+ * At the heart of the BGP Engine pthread is a select for the socket I/O, a
+ * Message Queue reader and a timer handler.  The Message Queue uses SIGUSR2 to
+ * kick the pthread into action if it is stopped on the select.
+ *
+ */
+
+/*==============================================================================
+ * The qpnexus for the BGP Engine.
+ *
+ *
+ */
+
+/*==============================================================================
+ * Start the BGP Engine Thread.
+ *
+ * Initialise the Engine Thread qpnexus
+ *
+ */
+
+/* BGP Engine side of bgp_engine_start() must call bgp_open_listeners()
+ * for which it needs the port and address from command line.
+ *
+ * Implemented in bgp_main.c
+ */
+
+/*==============================================================================
+ * Stop the BGP Engine Thread.
+ *
+ */
+
+/* BGP Engine side of bgp_engine_stop() must call bgp_close_listeners()
+ *
+ * Implemented in bgp_main.c
+ */
+
+/*==============================================================================
+ * The BGP Engine Thread main loop
+ *
+ * Processes:
+ *
+ *   1) connections with pending work -- local queue.
+ *
+ *      When a connection fills its output buffers, any further messages
+ *      requiring output are placed on the connection's pending queue.
+ *
+ *      When the output buffers empty sufficiently, some of those messages
+ *      can (finally) be processed.
+ *
+ *      So this is done first.
+ *
+ *      [This is also where stopped connections are finally reaped.]
+ *
+ *   2) messages coming from the Routeing Engine -- mqueue_queue.
+ *
+ *      These will mostly be BGP UPDATE messages, which will either be
+ *      processed into the relevant connection's output buffers, or end up
+ *      on its pending queue.
+ *
+ *      There is a flow control mechanism to prevent the Routeing Engine from
+ *      flooding the BGP Engine with UPDATE messages.
+ *
+ *      Other messages start/stop sessions and so on.
+ *
+ *   3) I/O -- qpselect
+ *
+ *      This deals with all active sockets for read/write/connect/accept.
+ *
+ *      Each time a socket is readable, one message is read and dispatched to
+ *      the Routeing Engine (or otherwise dealt with by the FSM).
+ *
+ *      Each time a socket is writable, as much as possible is written to it
+ *      from the connection's write buffer.  When the write buffer is drained,
+ *      the connection goes back onto the local queue.
+ *
+ *   4) Timers -- qtimers
+ *
+ *      Which generate FSM events.
+ *
+ * Implemented in qpnexus.c
+ *
+ */
+
+
+/*==============================================================================
+ * The write queue for the BGP Engine
+ *
+ * Each connection has a single message buffer.  When that has yet to be
+ *
+ *
+ */
+
+