src/libstrongswan/crypto/iv/iv_gen_seq.c

   1 /*
   2  * Copyright (C) 2013 Tobias Brunner
   3  * Hochschule fuer Technik Rapperswil
   4  *
   5  * This program is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License as published by the
   7  * Free Software Foundation; either version 2 of the License, or (at your
   8  * option) any later version.  See <http://www.fsf.org/copyleft/gpl.txt>.
   9  *
  10  * This program is distributed in the hope that it will be useful, but
  11  * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  12  * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  13  * for more details.
  14  */
  15
  16 #include "iv_gen_seq.h"
  17
  18 typedef struct private_iv_gen_t private_iv_gen_t;
  19
  20 /**
  21  * Private data of an iv_gen_t object.
  22  */
  23 struct private_iv_gen_t {
  24
  25         /**
  26          * Public iv_gen_t interface.
  27          */
  28         iv_gen_t public;
  29
  30         /**
  31          * sequence number
  32          */
  33         u_int64_t seq;
  34 };
  35
  36 METHOD(iv_gen_t, get_iv, bool,
  37         private_iv_gen_t *this, size_t size, u_int8_t *buffer)
  38 {
  39         u_int8_t iv[sizeof(u_int64_t)];
  40         size_t len = size;
  41
  42         if (this->seq == UINT64_MAX || len < sizeof(u_int64_t))
  43         {
  44                 return FALSE;
  45         }
  46         if (len > sizeof(u_int64_t))
  47         {
  48                 len = sizeof(u_int64_t);
  49                 memset(buffer, 0, size - len);
  50         }
  51         htoun64(iv, this->seq++);
  52         memcpy(buffer + size - len, iv + sizeof(u_int64_t) - len, len);
  53         return TRUE;
  54 }
  55
  56 METHOD(iv_gen_t, allocate_iv, bool,
  57         private_iv_gen_t *this, size_t size, chunk_t *chunk)
  58 {
  59         *chunk = chunk_alloc(size);
  60         if (!get_iv(this, chunk->len, chunk->ptr))
  61         {
  62                 chunk_free(chunk);
  63                 return FALSE;
  64         }
  65         return TRUE;
  66 }
  67
  68 METHOD(iv_gen_t, destroy, void,
  69         private_iv_gen_t *this)
  70 {
  71         free(this);
  72 }
  73
  74 iv_gen_t *iv_gen_seq_create()
  75 {
  76         private_iv_gen_t *this;
  77
  78         INIT(this,
  79                 .public = {
  80                         .get_iv = _get_iv,
  81                         .allocate_iv = _allocate_iv,
  82                         .destroy = _destroy,
  83                 },
  84         );
  85
  86         return &this->public;
  87 }