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/*
* Copyright (C) 2012 Tobias Brunner
* Copyright (C) 2005-2007 Martin Willi
* Copyright (C) 2005 Jan Hutter
* Hochschule fuer Technik Rapperswil
*
* This program 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 of the License, or (at your
* option) any later version. See <http://www.fsf.org/copyleft/gpl.txt>.
*
* 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.
*/
/**
* @defgroup receiver receiver
* @{ @ingroup network
*/
#ifndef RECEIVER_H_
#define RECEIVER_H_
typedef struct receiver_t receiver_t;
#include <library.h>
#include <networking/host.h>
#include <networking/packet.h>
/**
* Callback called for any received UDP encapsulated ESP packet.
*
* Implementation should be quick as the receiver doesn't receive any packets
* while calling this function.
*
* @param data data supplied during registration of the callback
* @param packet decapsulated ESP packet
*/
typedef void (*receiver_esp_cb_t)(void *data, packet_t *packet);
/**
* Receives packets from the socket and adds them to the job queue.
*
* The receiver uses a callback job, which reads on the blocking socket.
* A received packet is preparsed and a process_message_job is queued in the
* job queue.
*
* To endure DoS attacks, cookies are enabled when too many IKE_SAs are half
* open. The calculation of cookies is slightly different from the proposed
* method in RFC4306. We do not include a nonce, because we think the advantage
* we gain does not justify the overhead to parse the whole message.
* Instead of VersionIdOfSecret, we include a timestamp. This allows us to
* find out which key was used for cookie creation. Further, we can set a
* lifetime for the cookie, which allows us to reuse the secret for a longer
* time.
* COOKIE = time | sha1( IPi | SPIi | time | secret )
*
* The secret is changed after a certain amount of cookies sent. The old
* secret is stored to allow a clean migration between secret changes.
*
* Further, the number of half-initiated IKE_SAs is limited per peer. This
* makes it impossible for a peer to flood the server with its real IP address.
*/
struct receiver_t {
/**
* Register a callback which is called for any incoming ESP packets.
*
* @note Only the last callback registered will receive any packets.
*
* @param callback callback to register
* @param data data provided to callback
*/
void (*add_esp_cb)(receiver_t *this, receiver_esp_cb_t callback,
void *data);
/**
* Unregister a previously registered callback for ESP packets.
*
* @param callback previously registered callback
*/
void (*del_esp_cb)(receiver_t *this, receiver_esp_cb_t callback);
/**
* Destroys a receiver_t object.
*/
void (*destroy)(receiver_t *this);
};
/**
* Create a receiver_t object.
*
* The receiver thread will start working, get data
* from the socket and add those packets to the job queue.
*
* @return receiver_t object, NULL if initialization fails
*/
receiver_t * receiver_create(void);
#endif /** RECEIVER_H_ @}*/
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