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1.8.7

    1: /*
    2:  * Copyright (c) 2013 Todd C. Miller <Todd.Miller@courtesan.com>
    3:  *
    4:  * Permission to use, copy, modify, and distribute this software for any
    5:  * purpose with or without fee is hereby granted, provided that the above
    6:  * copyright notice and this permission notice appear in all copies.
    7:  *
    8:  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
    9:  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
   10:  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
   11:  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
   12:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
   13:  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
   14:  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
   15:  * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
   16:  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   17:  */
   18: 
   19: #include <config.h>
   20: 
   21: #include <sys/types.h>
   22: #include <stdio.h>
   23: #ifdef STDC_HEADERS
   24: # include <stdlib.h>
   25: # include <stddef.h>
   26: #else
   27: # ifdef HAVE_STDLIB_H
   28: #  include <stdlib.h>
   29: # endif
   30: #endif /* STDC_HEADERS */
   31: #ifdef HAVE_STRING_H
   32: # include <string.h>
   33: #endif /* HAVE_STRING_H */
   34: #ifdef HAVE_STRINGS_H
   35: # include <strings.h>
   36: #endif /* HAVE_STRINGS_H */
   37: 
   38: #include "missing.h"
   39: #include "sudo_debug.h"
   40: 
   41: /*
   42:  * Decode a NUL-terminated string in base64 format and store the
   43:  * result in dst.
   44:  */
   45: size_t
   46: base64_decode(const char *str, unsigned char *dst, size_t dsize)
   47: {
   48:     static const char b64[] =
   49: 	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
   50:     const unsigned char *dst0 = dst;
   51:     const unsigned char *dend = dst + dsize;
   52:     unsigned char ch[4];
   53:     char *pos;
   54:     int i;
   55:     debug_decl(base64_decode, SUDO_DEBUG_MATCH)
   56: 
   57:     /*
   58:      * Convert from base64 to binary.  Each base64 char holds 6 bits of data
   59:      * so 4 base64 chars equals 3 chars of data.
   60:      * Padding (with the '=' char) may or may not be present.
   61:      */
   62:     while (*str != '\0') {
   63: 	for (i = 0; i < 4; i++) {
   64: 	    switch (*str) {
   65: 	    case '=':
   66: 		str++;
   67: 		/* FALLTHROUGH */
   68: 	    case '\0':
   69: 		ch[i] = '=';
   70: 		break;
   71: 	    default:
   72: 		if ((pos = strchr(b64, *str++)) == NULL)
   73: 		    debug_return_size_t((size_t)-1);
   74: 		ch[i] = (unsigned char)(pos - b64);
   75: 		break;
   76: 	    }
   77: 	}
   78: 	if (ch[0] == '=' || ch[1] == '=' || dst == dend)
   79: 	    break;
   80: 	*dst++ = (ch[0] << 2) | ((ch[1] & 0x30) >> 4);
   81: 	if (ch[2] == '=' || dst == dend)
   82: 	    break;
   83: 	*dst++ = ((ch[1] & 0x0f) << 4) | ((ch[2] & 0x3c) >> 2);
   84: 	if (ch[3] == '=' || dst == dend)
   85: 	    break;
   86: 	*dst++ = ((ch[2] & 0x03) << 6) | ch[3];
   87:     }
   88:     debug_return_size_t((size_t)(dst - dst0));
   89: }