wsutil/base64.c

   1 /* base64.c
   2  * Base-64 conversion
   3  *
   4  * Wireshark - Network traffic analyzer
   5  * By Gerald Combs <gerald@wireshark.org>
   6  * Copyright 1998 Gerald Combs
   7  *
   8  * This program is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU General Public License
  10  * as published by the Free Software Foundation; either version 2
  11  * of the License, or (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License
  19  * along with this program; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  */
  22
  23 #include "config.h"
  24
  25 #include <string.h>
  26 #include "base64.h"
  27
  28 /* Decode a base64 string in-place - simple and slow algorithm.
  29    Return length of result. Taken from rproxy/librsync/base64.c by
  30    Andrew Tridgell. */
  31
  32 size_t ws_base64_decode_inplace(char *s)
  33 {
  34         static const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/\r\n";
  35         int bit_offset, byte_offset, idx, i;
  36         unsigned char *d = (unsigned char *)s;
  37         char *p;
  38         int  cr_idx;
  39
  40         /* we will allow CR and LF - but ignore them */
  41         cr_idx = (int) (strchr(b64, '\r') - b64);
  42
  43         i = 0;
  44
  45         while (*s && (p=strchr(b64, *s))) {
  46                 idx = (int)(p - b64);
  47                 if(idx < cr_idx) {
  48                         byte_offset = (i*6)/8;
  49                         bit_offset = (i*6)%8;
  50                         d[byte_offset] &= ~((1<<(8-bit_offset))-1);
  51                         if (bit_offset < 3) {
  52                                 d[byte_offset] |= (idx << (2-bit_offset));
  53                         } else {
  54                                 d[byte_offset] |= (idx >> (bit_offset-2));
  55                                 d[byte_offset+1] = 0;
  56                                 d[byte_offset+1] |= (idx << (8-(bit_offset-2))) & 0xFF;
  57                         }
  58                         i++;
  59                 }
  60                 s++;
  61         }
  62
  63         d[i*3/4] = 0;
  64         return i*3/4;
  65 }
  66
  67 /*
  68  * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
  69  *
  70  * Local variables:
  71  * c-basic-offset: 8
  72  * tab-width: 8
  73  * indent-tabs-mode: t
  74  * End:
  75  *
  76  * vi: set shiftwidth=8 tabstop=8 noexpandtab:
  77  * :indentSize=8:tabSize=8:noTabs=false:
  78  */