epan/base64.c

   1 /* base64.c
   2  * Base-64 conversion
   3  *
   4  * $Id$
   5  *
   6  * Wireshark - Network traffic analyzer
   7  * By Gerald Combs <gerald@wireshark.org>
   8  * Copyright 1998 Gerald Combs
   9  *
  10  * This program is free software; you can redistribute it and/or
  11  * modify it under the terms of the GNU General Public License
  12  * as published by the Free Software Foundation; either version 2
  13  * of the License, or (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful,
  16  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18  * GNU General Public License for more details.
  19  *
  20  * You should have received a copy of the GNU General Public License
  21  * along with this program; if not, write to the Free Software
  22  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  23  */
  24
  25 #include "config.h"
  26
  27 #include <string.h>
  28 #include "base64.h"
  29
  30 /* Decode a base64 string in-place - simple and slow algorithm.
  31    Return length of result. Taken from rproxy/librsync/base64.c by
  32    Andrew Tridgell. */
  33
  34 size_t epan_base64_decode(char *s)
  35 {
  36         static const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/\r\n";
  37         int bit_offset, byte_offset, idx, i;
  38         unsigned char *d = (unsigned char *)s;
  39         char *p;
  40         int  cr_idx;
  41
  42         /* we will allow CR and LF - but ignore them */
  43         cr_idx = (int) (strchr(b64, '\r') - b64);
  44
  45         i=0;
  46
  47         while (*s && (p=strchr(b64, *s))) {
  48                 idx = (int)(p - b64);
  49                 if(idx < cr_idx) {
  50                         byte_offset = (i*6)/8;
  51                         bit_offset = (i*6)%8;
  52                         d[byte_offset] &= ~((1<<(8-bit_offset))-1);
  53                         if (bit_offset < 3) {
  54                                 d[byte_offset] |= (idx << (2-bit_offset));
  55                         } else {
  56                                 d[byte_offset] |= (idx >> (bit_offset-2));
  57                                 d[byte_offset+1] = 0;
  58                                 d[byte_offset+1] |= (idx << (8-(bit_offset-2))) & 0xFF;
  59                         }
  60                         i++;
  61                 }
  62                 s++;
  63         }
  64
  65         d[i*3/4] = 0;
  66         return i*3/4;
  67 }
  68
  69 /* Return a tvb that contains the binary representation of a base64
  70    string */
  71
  72 tvbuff_t *
  73 base64_to_tvb(tvbuff_t *parent, const char *base64)
  74 {
  75   tvbuff_t *tvb;
  76   char *data = g_strdup(base64);
  77   gint len;
  78
  79   len = (gint) epan_base64_decode(data);
  80   tvb = tvb_new_child_real_data(parent, (const guint8 *)data, len, len);
  81
  82   tvb_set_free_cb(tvb, g_free);
  83
  84   return tvb;
  85 }