lib/util/base64.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba utility functions
   4
   5    Copyright (C) Andrew Tridgell 1992-2001
   6    Copyright (C) Simo Sorce      2001-2002
   7    Copyright (C) Martin Pool     2003
   8    Copyright (C) James Peach     2006
   9    Copyright (C) Jeremy Allison  1992-2007
  10
  11    This program is free software; you can redistribute it and/or modify
  12    it under the terms of the GNU General Public License as published by
  13    the Free Software Foundation; either version 3 of the License, or
  14    (at your option) any later version.
  15
  16    This program is distributed in the hope that it will be useful,
  17    but WITHOUT ANY WARRANTY; without even the implied warranty of
  18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  19    GNU General Public License for more details.
  20
  21    You should have received a copy of the GNU General Public License
  22    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  23 */
  24
  25 #include "includes.h"
  26
  27 static const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  28
  29 /**
  30  * Decode a base64 string into a DATA_BLOB - simple and slow algorithm
  31  **/
  32 _PUBLIC_ DATA_BLOB base64_decode_data_blob(const char *s)
  33 {
  34         int bit_offset, byte_offset, idx, i, n;
  35         DATA_BLOB decoded = data_blob(s, strlen(s)+1);
  36         unsigned char *d = decoded.data;
  37         char *p;
  38
  39         n=i=0;
  40
  41         while (*s && (p=strchr_m(b64,*s))) {
  42                 idx = (int)(p - b64);
  43                 byte_offset = (i*6)/8;
  44                 bit_offset = (i*6)%8;
  45                 d[byte_offset] &= ~((1<<(8-bit_offset))-1);
  46                 if (bit_offset < 3) {
  47                         d[byte_offset] |= (idx << (2-bit_offset));
  48                         n = byte_offset+1;
  49                 } else {
  50                         d[byte_offset] |= (idx >> (bit_offset-2));
  51                         d[byte_offset+1] = 0;
  52                         d[byte_offset+1] |= (idx << (8-(bit_offset-2))) & 0xFF;
  53                         n = byte_offset+2;
  54                 }
  55                 s++; i++;
  56         }
  57
  58         if ((n > 0) && (*s == '=')) {
  59                 n -= 1;
  60         }
  61
  62         /* fix up length */
  63         decoded.length = n;
  64         return decoded;
  65 }
  66
  67 /**
  68  * Decode a base64 string in-place - wrapper for the above
  69  **/
  70 _PUBLIC_ void base64_decode_inplace(char *s)
  71 {
  72         DATA_BLOB decoded = base64_decode_data_blob(s);
  73
  74         if ( decoded.length != 0 ) {
  75                 memcpy(s, decoded.data, decoded.length);
  76
  77                 /* null terminate */
  78                 s[decoded.length] = '\0';
  79         } else {
  80                 *s = '\0';
  81         }
  82
  83         data_blob_free(&decoded);
  84 }
  85
  86 /**
  87  * Encode a base64 string into a talloc()ed string caller to free.
  88  *
  89  * From SQUID: adopted from http://ftp.sunet.se/pub2/gnu/vm/base64-encode.c
  90  * with adjustments
  91  **/
  92
  93 _PUBLIC_ char *base64_encode_data_blob(TALLOC_CTX *mem_ctx, DATA_BLOB data)
  94 {
  95         int bits = 0;
  96         int char_count = 0;
  97         size_t out_cnt, len, output_len;
  98         char *result;
  99
 100         if (!data.length || !data.data)
 101                 return NULL;
 102
 103         out_cnt = 0;
 104         len = data.length;
 105         output_len = data.length * 2 + 4; /* Account for closing bytes. 4 is
 106                                            * random but should be enough for
 107                                            * the = and \0 */
 108         result = talloc_array(mem_ctx, char, output_len); /* get us plenty of space */
 109         SMB_ASSERT(result != NULL);
 110
 111         while (len--) {
 112                 int c = (unsigned char) *(data.data++);
 113                 bits += c;
 114                 char_count++;
 115                 if (char_count == 3) {
 116                         result[out_cnt++] = b64[bits >> 18];
 117                         result[out_cnt++] = b64[(bits >> 12) & 0x3f];
 118                         result[out_cnt++] = b64[(bits >> 6) & 0x3f];
 119                         result[out_cnt++] = b64[bits & 0x3f];
 120                         bits = 0;
 121                         char_count = 0;
 122                 } else {
 123                         bits <<= 8;
 124                 }
 125         }
 126         if (char_count != 0) {
 127                 bits <<= 16 - (8 * char_count);
 128                 result[out_cnt++] = b64[bits >> 18];
 129                 result[out_cnt++] = b64[(bits >> 12) & 0x3f];
 130                 if (char_count == 1) {
 131                         result[out_cnt++] = '=';
 132                         result[out_cnt++] = '=';
 133                 } else {
 134                         result[out_cnt++] = b64[(bits >> 6) & 0x3f];
 135                         result[out_cnt++] = '=';
 136                 }
 137         }
 138         result[out_cnt] = '\0'; /* terminate */
 139         return result;
 140 }
 141