diff options
Diffstat (limited to 'doc/doxygen/doc_mainpage.h')
| -rw-r--r-- | doc/doxygen/doc_mainpage.h | 161 |
1 files changed, 161 insertions, 0 deletions
diff --git a/doc/doxygen/doc_mainpage.h b/doc/doxygen/doc_mainpage.h new file mode 100644 index 0000000..6016d07 --- /dev/null +++ b/doc/doxygen/doc_mainpage.h @@ -0,0 +1,161 @@ +/* + * 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 page documentation file. + */ + +/** + * @mainpage OpenVPN source code documentation + * + * This documentation describes the internal structure of OpenVPN. It was + * automatically generated from specially formatted comment blocks in + * OpenVPN's source code using Doxygen. (See + * http://www.stack.nl/~dimitri/doxygen/ for more information on Doxygen) + * + * The \ref mainpage_modules "Modules section" below gives an introduction + * into the high-level module concepts used throughout this documentation. + * The \ref mainpage_relatedpages "Related Pages section" below describes + * various special subjects related to OpenVPN's implementation which are + * discussed in the related pages section. + * + * @section mainpage_modules Modules + * + * For the purpose of describing the internal structure of OpenVPN, this + * documentation and the underlying source code has been broken up into a + * number of conceptually well-defined parts, known as modules. Each + * module plays a specific role within the OpenVPN process, and in most + * cases each module has a clear interfacing strategy for interacting with + * other modules. + * + * The following modules have been defined: + * - Driver module: + * - The \link eventloop Main Event Loop\endlink: this module drives the + * event handling of OpenVPN. It implements various types of + * select-loop which wait until an event happens, and then delegate + * the handling of that event to the appropriate module. + * - Network interface modules: + * - The \link external_multiplexer External Multiplexer\endlink: this + * module sends and receives packets to and from remote OpenVPN peers + * over the external network interface. It also takes care of + * demultiplexing received packets to their appropriate VPN tunnel and + * splitting control channel and data channel packets. + * - The \link internal_multiplexer Internal Multiplexer\endlink: this + * module sends and receives packets to and from locally reachable + * posts over the virtual tun/tap network interface. It also takes + * care of determining through which VPN tunnel a received packet must + * be sent to reach its destination. + * - Control channel modules: + * - The \link reliable Reliability Layer\endlink: this module offers a + * %reliable and sequential transport layer for control channel + * messages. + * - The \link control_tls Control Channel TLS module\endlink: this + * module offers a secure encapsulation of control channel messages + * using the TLS protocol. + * - The \link control_processor Control Channel Processor\endlink: his + * module manages the setup, maintenance, and shut down of VPN + * tunnels. + * - Data channel modules: + * - The \link data_control Data Channel Control module\endlink: this + * module controls the processing of data channel packets and, + * depending on the settings of the packet's VPN tunnel, passes the + * packet to the three modules below for handling. + * - The \link data_crypto Data Channel Crypto module\endlink: this + * module performs security operations on data channel packets. + * - The \link fragmentation Data Channel Fragmentation module\endlink: + * this module offers fragmentation of data channel packets larger + * than the VPN tunnel's MTU. + * - The \link compression Data Channel Compression module\endlink: this + * module offers compression of data channel packets. + * + * @subsection mainpage_modules_example Example event: receiving a packet + * + * OpenVPN handles many types of events during operation. These include + * external events, such as network traffic being received, and internal + * events, such as a %key session timing out causing renegotiation. An + * example event, receiving a packet over the network, is described here + * together with which modules play what roles: + * -# The \link eventloop Main Event Loop\endlink detects that a packet + * can be read from the external or the virtual tun/tap network + * interface. + * -# The \link eventloop Main Event Loop\endlink calls the \link + * external_multiplexer External Multiplexer\endlink or \link + * internal_multiplexer Internal Multiplexer\endlink to read and + * process the packet. + * -# The multiplexer module determines the type of packet and its + * destination, and passes the packet on to the appropriate handling + * module: + * - A control channel packet received by the \link + * external_multiplexer External Multiplexer\endlink is passed on + * through the \link reliable Reliability Layer\endlink and the \link + * control_tls Control Channel TLS module\endlink to the \link + * control_processor Control Channel Processor\endlink. + * - A data channel packet received by either multiplexer module is + * passed on to the \link data_control Data Channel Control + * module\endlink. + * -# The packet is processed by the appropriate control channel or data + * channel modules. + * -# If, after processing the packet, a resulting packet is generated + * that needs to be sent to a local or remote destination, it is given + * to the \link external_multiplexer External Multiplexer\endlink or + * \link internal_multiplexer Internal Multiplexer\endlink for sending. + * -# If a packet is waiting to be sent by either multiplexer module and + * the \link eventloop Main Event Loop\endlink detects that data can be + * written to the associated network interface, it calls the + * multiplexer module to send the packet. + * + * @section mainpage_relatedpages Related pages + * + * This documentation includes a number of descriptions of various aspects + * of OpenVPN and its implementation. These are not directly related to + * one module, function, or data structure, and are therefore listed + * separately under "Related Pages". + * + * @subsection mainpage_relatedpages_key_generation Data channel key generation + * + * The @ref key_generation "Data channel key generation" related page + * describes how, during VPN tunnel setup and renegotiation, OpenVPN peers + * generate and exchange the %key material required for the symmetric + * encryption/decryption and HMAC signing/verifying security operations + * performed on data channel packets. + * + * @subsection mainpage_relatedpages_tunnel_state VPN tunnel state + * + * The @ref tunnel_state "Structure of VPN tunnel state storage" related + * page describes how an OpenVPN process manages the state information + * associated with its active VPN tunnels. + * + * @subsection mainpage_relatedpages_network_protocol Network protocol + * + * The @ref network_protocol "Network protocol" related page describes the + * format and content of VPN tunnel packets exchanged between OpenVPN + * peers. + * + * @subsection mainpage_relatedpages_memory_management Memory management + * + * The @ref memory_management "Memory management strategies" related page + * gives a brief introduction into OpenVPN's memory %buffer library and + * garbage collection facilities. + */ |