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Annotation of embedaddon/strongswan/src/libcharon/network/receiver.h, revision 1.1.1.1

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_ @}*/