Moved packet_t to libstrongswan
[strongswan.git] / src / libcharon / network / receiver.h
1 /*
2 * Copyright (C) 2012 Tobias Brunner
3 * Copyright (C) 2005-2007 Martin Willi
4 * Copyright (C) 2005 Jan Hutter
5 * 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 <utils/host.h>
30 #include <utils/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_ @}*/