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authorBernhard Schmidt <berni@debian.org>2020-08-15 21:29:50 +0200
committerBernhard Schmidt <berni@debian.org>2020-08-15 21:29:50 +0200
commit1079962e4c06f88a54e50d997c1b7e84303d30b4 (patch)
tree4d019426928435425214ccedd6f89b70dbdf035d /doc/doxygen/doc_eventloop.h
parent620785fe268a1221c1ba7a9cb5a70f3140a4f1ca (diff)
New upstream version 2.5~beta1upstream/2.5_beta1
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+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2010-2018 Fox Crypto B.V. <openvpn@fox-it.com>
+ *
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file
+ * Main Event Loop module documentation file.
+ */
+
+/**
+ * @defgroup eventloop Main Event Loop module
+ *
+ * This main event loop module drives the packet processing of OpenVPN.
+ *
+ * OpenVPN is an event driven system. Its activities are driven by a main
+ * event loop, which repeatedly waits for one of several predefined events
+ * to occur, and then calls the appropriate module to handle the event.
+ * The major types of network events that OpenVPN processes are:
+ * - A packet can be read from the external network interface.
+ * - The main event loop activates the \link external_multiplexer
+ * External Multiplexer\endlink to read and process the packet.
+ * - A packet can be read from the virtual tun/tap network interface.
+ * - The main event loop activates the \link internal_multiplexer
+ * Internal Multiplexer\endlink to read and process the packet.
+ * - If a packet is ready to be sent out as a VPN tunnel packet: the
+ * external network interface can be written to.
+ * - The main event loop activates the \link external_multiplexer
+ * External Multiplexer\endlink to send the packet.
+ * - If a packet is ready to be sent to a locally reachable destination:
+ * the virtual tun/tap network interface can be written to.
+ * - The main event loop activates the \link internal_multiplexer
+ * Internal Multiplexer\endlink to send the packet.
+ *
+ * Beside these external events, OpenVPN also processes other types of
+ * internal events. These include scheduled events, such as resending of
+ * non-acknowledged control channel messages.
+ *
+ * @par Main event loop implementations
+ *
+ * Depending on the mode in which OpenVPN is running, a different main
+ * event loop function is called to drive the event processing. The
+ * following implementations are available:
+ * - Client mode using UDP or TCP: \c tunnel_point_to_point()
+ * - Server mode using UDP: \c tunnel_server_udp_single_threaded()
+ * - Server mode using TCP: \c tunnel_server_tcp()
+ */