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Annotation of embedaddon/strongswan/src/libcharon/network/receiver.h, revision 1.1

1.1     ! misho       1: /*
        !             2:  * Copyright (C) 2012 Tobias Brunner
        !             3:  * Copyright (C) 2005-2007 Martin Willi
        !             4:  * Copyright (C) 2005 Jan Hutter
        !             5:  * HSR Hochschule fuer Technik Rapperswil
        !             6:  *
        !             7:  * This program is free software; you can redistribute it and/or modify it
        !             8:  * under the terms of the GNU General Public License as published by the
        !             9:  * Free Software Foundation; either version 2 of the License, or (at your
        !            10:  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
        !            11:  *
        !            12:  * This program is distributed in the hope that it will be useful, but
        !            13:  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
        !            14:  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
        !            15:  * for more details.
        !            16:  */
        !            17: 
        !            18: /**
        !            19:  * @defgroup receiver receiver
        !            20:  * @{ @ingroup network
        !            21:  */
        !            22: 
        !            23: #ifndef RECEIVER_H_
        !            24: #define RECEIVER_H_
        !            25: 
        !            26: typedef struct receiver_t receiver_t;
        !            27: 
        !            28: #include <library.h>
        !            29: #include <networking/host.h>
        !            30: #include <networking/packet.h>
        !            31: 
        !            32: /**
        !            33:  * Callback called for any received UDP encapsulated ESP packet.
        !            34:  *
        !            35:  * Implementation should be quick as the receiver doesn't receive any packets
        !            36:  * while calling this function.
        !            37:  *
        !            38:  * @param data                 data supplied during registration of the callback
        !            39:  * @param packet               decapsulated ESP packet
        !            40:  */
        !            41: typedef void (*receiver_esp_cb_t)(void *data, packet_t *packet);
        !            42: 
        !            43: /**
        !            44:  * Receives packets from the socket and adds them to the job queue.
        !            45:  *
        !            46:  * The receiver uses a callback job, which reads on the blocking socket.
        !            47:  * A received packet is preparsed and a process_message_job is queued in the
        !            48:  * job queue.
        !            49:  *
        !            50:  * To endure DoS attacks, cookies are enabled when too many IKE_SAs are half
        !            51:  * open. The calculation of cookies is slightly different from the proposed
        !            52:  * method in RFC4306. We do not include a nonce, because we think the advantage
        !            53:  * we gain does not justify the overhead to parse the whole message.
        !            54:  * Instead of VersionIdOfSecret, we include a timestamp. This allows us to
        !            55:  * find out which key was used for cookie creation. Further, we can set a
        !            56:  * lifetime for the cookie, which allows us to reuse the secret for a longer
        !            57:  * time.
        !            58:  *              COOKIE = time | sha1( IPi | SPIi | time | secret )
        !            59:  *
        !            60:  * The secret is changed after a certain amount of cookies sent. The old
        !            61:  * secret is stored to allow a clean migration between secret changes.
        !            62:  *
        !            63:  * Further, the number of half-initiated IKE_SAs is limited per peer. This
        !            64:  * makes it impossible for a peer to flood the server with its real IP address.
        !            65:  */
        !            66: struct receiver_t {
        !            67: 
        !            68:        /**
        !            69:         * Register a callback which is called for any incoming ESP packets.
        !            70:         *
        !            71:         * @note Only the last callback registered will receive any packets.
        !            72:         *
        !            73:         * @param callback              callback to register
        !            74:         * @param data                  data provided to callback
        !            75:         */
        !            76:        void (*add_esp_cb)(receiver_t *this, receiver_esp_cb_t callback,
        !            77:                                           void *data);
        !            78: 
        !            79:        /**
        !            80:         * Unregister a previously registered callback for ESP packets.
        !            81:         *
        !            82:         * @param callback              previously registered callback
        !            83:         */
        !            84:        void (*del_esp_cb)(receiver_t *this, receiver_esp_cb_t callback);
        !            85: 
        !            86:        /**
        !            87:         * Destroys a receiver_t object.
        !            88:         */
        !            89:        void (*destroy)(receiver_t *this);
        !            90: };
        !            91: 
        !            92: /**
        !            93:  * Create a receiver_t object.
        !            94:  *
        !            95:  * The receiver thread will start working, get data
        !            96:  * from the socket and add those packets to the job queue.
        !            97:  *
        !            98:  * @return     receiver_t object, NULL if initialization fails
        !            99:  */
        !           100: receiver_t * receiver_create(void);
        !           101: 
        !           102: #endif /** RECEIVER_H_ @}*/