src/charon/config/configuration.c

   1 /**
   2  * @file configuration.c
   3  *
   4  * @brief Implementation of configuration_t.
   5  *
   6  */
   7
   8 /*
   9  * Copyright (C) 2006 Martin Willi
  10  * Hochschule fuer Technik Rapperswil
  11  *
  12  * This program is free software; you can redistribute it and/or modify it
  13  * under the terms of the GNU General Public License as published by the
  14  * Free Software Foundation; either version 2 of the License, or (at your
  15  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
  16  *
  17  * This program is distributed in the hope that it will be useful, but
  18  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  19  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  20  * for more details.
  21  */
  22
  23 #include <stdlib.h>
  24 #include <math.h>
  25
  26 #include "configuration.h"
  27
  28 #include <library.h>
  29
  30 /**
  31  * Timeout in milliseconds after that a half open IKE_SA gets deleted.
  32  */
  33 #define HALF_OPEN_IKE_SA_TIMEOUT 30000
  34
  35 /**
  36  * Retransmission uses a backoff algorithm. The timeout is calculated using
  37  * TIMEOUT * (BASE ** try).
  38  * When try reaches TRIES, retransmission is given up.
  39  *
  40  * Using an initial TIMEOUT of 4s, a BASE of 1.8, and 5 TRIES gives us:
  41  *
  42  *                        | relative | absolute
  43  * ---------------------------------------------------------
  44  * 4s * (1.8 ** (0  % 5)) =    4s         4s
  45  * 4s * (1.8 ** (1  % 5)) =    7s        11s
  46  * 4s * (1.8 ** (2  % 5)) =   13s        24s
  47  * 4s * (1.8 ** (3  % 5)) =   23s        47s
  48  * 4s * (1.8 ** (4  % 5)) =   42s        89s
  49  * 4s * (1.8 ** (5  % 5)) =   76s       165s
  50  *
  51  * The peer is considered dead after 2min 45s when no reply comes in.
  52  */
  53
  54 /**
  55  * First retransmit timeout in milliseconds.
  56  * Timeout value is increasing in each retransmit round.
  57  */
  58 #define RETRANSMIT_TIMEOUT 4000
  59
  60 /**
  61  * Base which is raised to the power of the retransmission count.
  62  */
  63 #define RETRANSMIT_BASE 1.8
  64
  65 /**
  66  * Number of retransmits done in a retransmit sequence
  67  */
  68 #define RETRANSMIT_TRIES 5
  69
  70 /**
  71  * Keepalive interval in seconds.
  72  */
  73 #define KEEPALIVE_INTERVAL 20
  74
  75 /**
  76  * retry interval in seconds.
  77  */
  78 #define RETRY_INTERVAL 15
  79
  80 /**
  81  * jitter to user for retrying
  82  */
  83 #define RETRY_JITTER 5
  84
  85
  86 typedef struct private_configuration_t private_configuration_t;
  87
  88 /**
  89  * Private data of an configuration_t object.
  90  */
  91 struct private_configuration_t {
  92
  93         /**
  94          * Public part of configuration_t object.
  95          */
  96         configuration_t public;
  97
  98 };
  99
 100 /**
 101  * Implementation of configuration_t.get_retransmit_timeout.
 102  */
 103 static u_int32_t get_retransmit_timeout (private_configuration_t *this,
 104                                                                                  u_int32_t retransmit_count)
 105 {
 106         if (retransmit_count > RETRANSMIT_TRIES)
 107         {
 108                 /* give up */
 109                 return 0;
 110         }
 111         return (u_int32_t)
 112                                 (RETRANSMIT_TIMEOUT * pow(RETRANSMIT_BASE, retransmit_count));
 113 }
 114
 115 /**
 116  * Implementation of configuration_t.get_half_open_ike_sa_timeout.
 117  */
 118 static u_int32_t get_half_open_ike_sa_timeout (private_configuration_t *this)
 119 {
 120         return HALF_OPEN_IKE_SA_TIMEOUT;
 121 }
 122
 123 /**
 124  * Implementation of configuration_t.get_keepalive_interval.
 125  */
 126 static u_int32_t get_keepalive_interval (private_configuration_t *this)
 127 {
 128         return KEEPALIVE_INTERVAL;
 129 }
 130
 131 /**
 132  * Implementation of configuration_t.get_retry_interval.
 133  */
 134 static u_int32_t get_retry_interval (private_configuration_t *this)
 135 {
 136         return RETRY_INTERVAL - (random() % RETRY_JITTER);
 137 }
 138
 139 /**
 140  * Implementation of configuration_t.destroy.
 141  */
 142 static void destroy(private_configuration_t *this)
 143 {
 144         free(this);
 145 }
 146
 147 /*
 148  * Described in header-file
 149  */
 150 configuration_t *configuration_create()
 151 {
 152         private_configuration_t *this = malloc_thing(private_configuration_t);
 153
 154         /* public functions */
 155         this->public.destroy = (void(*)(configuration_t*))destroy;
 156         this->public.get_retransmit_timeout = (u_int32_t (*) (configuration_t*,u_int32_t))get_retransmit_timeout;
 157         this->public.get_half_open_ike_sa_timeout = (u_int32_t (*) (configuration_t*)) get_half_open_ike_sa_timeout;
 158         this->public.get_keepalive_interval = (u_int32_t (*) (configuration_t*)) get_keepalive_interval;
 159         this->public.get_retry_interval = (u_int32_t (*) (configuration_t*)) get_retry_interval;
 160
 161         return (&this->public);
 162 }