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 "replace.h"
  26 #include "lib/util/base64.h"
  27
  28 static const char b64[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  29
  30 /**
  31  * Decode a base64 string into a DATA_BLOB - simple and slow algorithm.
  32  *
  33  * A DATA_BLOB like {.data = NULL, length = 0} indicates memory error.
  34  *
  35  * Decoding stops at the first invalid character.
  36  **/
  37 _PUBLIC_ DATA_BLOB base64_decode_data_blob_talloc(TALLOC_CTX *mem_ctx, const char *s)
  38 {
  39         int bit_offset, byte_offset, idx, i, n;
  40         DATA_BLOB decoded = data_blob_talloc(mem_ctx, s, strlen(s)+1);
  41         unsigned char *d = decoded.data;
  42         char *p;
  43
  44         if (decoded.data == NULL) {
  45                 decoded.length = 0;
  46                 return decoded;
  47         }
  48
  49         n=i=0;
  50
  51         while (*s && (p=strchr(b64,*s))) {
  52                 idx = (int)(p - b64);
  53                 byte_offset = (i*6)/8;
  54                 bit_offset = (i*6)%8;
  55                 d[byte_offset] &= ~((1<<(8-bit_offset))-1);
  56                 if (bit_offset < 3) {
  57                         d[byte_offset] |= (idx << (2-bit_offset));
  58                         n = byte_offset+1;
  59                 } else {
  60                         d[byte_offset] |= (idx >> (bit_offset-2));
  61                         d[byte_offset+1] = (idx << (8-(bit_offset-2))) & 0xFF;
  62                         n = byte_offset+2;
  63                 }
  64                 s++; i++;
  65         }
  66
  67         if ((n > 0) && (*s == '=')) {
  68                 n -= 1;
  69         }
  70
  71         /* fix up length */
  72         decoded.length = n;
  73         decoded.data = talloc_realloc(mem_ctx, decoded.data, uint8_t, n);
  74         return decoded;
  75 }
  76
  77 /**
  78  * Decode a base64 string into a DATA_BLOB - simple and slow algorithm
  79  **/
  80 _PUBLIC_ DATA_BLOB base64_decode_data_blob(const char *s)
  81 {
  82         return base64_decode_data_blob_talloc(NULL, s);
  83 }
  84
  85 /**
  86  * Decode a base64 string in-place - wrapper for the above
  87  **/
  88 _PUBLIC_ void base64_decode_inplace(char *s)
  89 {
  90         DATA_BLOB decoded = base64_decode_data_blob(s);
  91
  92         if ( decoded.length != 0 ) {
  93                 memcpy(s, decoded.data, decoded.length);
  94
  95                 /* null terminate */
  96                 s[decoded.length] = '\0';
  97         } else {
  98                 *s = '\0';
  99         }
 100
 101         data_blob_free(&decoded);
 102 }
 103
 104 /**
 105  * Encode a base64 string into a talloc()ed string caller to free.
 106  *
 107  * From SQUID: adopted from http://ftp.sunet.se/pub2/gnu/vm/base64-encode.c
 108  * with adjustments
 109  **/
 110
 111 _PUBLIC_ char *base64_encode_data_blob(TALLOC_CTX *mem_ctx, DATA_BLOB data)
 112 {
 113         int bits = 0;
 114         int char_count = 0;
 115         size_t out_cnt, len, output_len;
 116         char *result;
 117
 118         /*
 119          * Note: we return NULL for a zero-length blob, even though it can be
 120          * encoded as a zero length string in base64.
 121          *
 122          * FIXME, perhaps, but we need to check carefully before changing
 123          * this.
 124          */
 125         if (data.length == 0 || data.data == NULL) {
 126                 return NULL;
 127         }
 128
 129         out_cnt = 0;
 130         len = data.length;
 131         output_len = data.length * 2 + 4; /* Account for closing bytes. 4 is
 132                                            * random but should be enough for
 133                                            * the = and \0 */
 134         result = talloc_array(mem_ctx, char, output_len); /* get us plenty of space */
 135         if (result == NULL) {
 136                 return NULL;
 137         }
 138
 139         while (len--) {
 140                 int c = (unsigned char) *(data.data++);
 141                 bits += c;
 142                 char_count++;
 143                 if (char_count == 3) {
 144                         result[out_cnt++] = b64[bits >> 18];
 145                         result[out_cnt++] = b64[(bits >> 12) & 0x3f];
 146                         result[out_cnt++] = b64[(bits >> 6) & 0x3f];
 147                         result[out_cnt++] = b64[bits & 0x3f];
 148                         bits = 0;
 149                         char_count = 0;
 150                 } else {
 151                         bits <<= 8;
 152                 }
 153         }
 154         if (char_count != 0) {
 155                 bits <<= 16 - (8 * char_count);
 156                 result[out_cnt++] = b64[bits >> 18];
 157                 result[out_cnt++] = b64[(bits >> 12) & 0x3f];
 158                 if (char_count == 1) {
 159                         result[out_cnt++] = '=';
 160                         result[out_cnt++] = '=';
 161                 } else {
 162                         result[out_cnt++] = b64[(bits >> 6) & 0x3f];
 163                         result[out_cnt++] = '=';
 164                 }
 165         }
 166         result[out_cnt] = '\0'; /* terminate */
 167         return result;
 168 }
 169