89 lines
2.6 KiB
C
89 lines
2.6 KiB
C
/*
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* Copyright (c) 2013-2014 Todd C. Miller <Todd.Miller@courtesan.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <config.h>
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#include <sys/types.h>
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#include <stdio.h>
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#ifdef STDC_HEADERS
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# include <stdlib.h>
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# include <stddef.h>
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#else
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# ifdef HAVE_STDLIB_H
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# include <stdlib.h>
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# endif
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#endif /* STDC_HEADERS */
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#ifdef HAVE_STRING_H
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# include <string.h>
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#endif /* HAVE_STRING_H */
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#ifdef HAVE_STRINGS_H
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# include <strings.h>
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#endif /* HAVE_STRINGS_H */
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#include "sudoers.h"
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/*
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* Decode a NUL-terminated string in base64 format and store the
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* result in dst.
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*/
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size_t
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base64_decode(const char *str, unsigned char *dst, size_t dsize)
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{
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static const char b64[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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const unsigned char *dst0 = dst;
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const unsigned char *dend = dst + dsize;
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unsigned char ch[4];
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char *pos;
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int i;
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debug_decl(base64_decode, SUDOERS_DEBUG_MATCH, sudoers_debug_instance)
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/*
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* Convert from base64 to binary. Each base64 char holds 6 bits of data
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* so 4 base64 chars equals 3 chars of data.
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* Padding (with the '=' char) may or may not be present.
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*/
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while (*str != '\0') {
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for (i = 0; i < 4; i++) {
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switch (*str) {
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case '=':
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str++;
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/* FALLTHROUGH */
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case '\0':
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ch[i] = '=';
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break;
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default:
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if ((pos = strchr(b64, *str++)) == NULL)
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debug_return_size_t((size_t)-1);
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ch[i] = (unsigned char)(pos - b64);
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break;
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}
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}
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if (ch[0] == '=' || ch[1] == '=' || dst == dend)
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break;
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*dst++ = (ch[0] << 2) | ((ch[1] & 0x30) >> 4);
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if (ch[2] == '=' || dst == dend)
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break;
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*dst++ = ((ch[1] & 0x0f) << 4) | ((ch[2] & 0x3c) >> 2);
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if (ch[3] == '=' || dst == dend)
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break;
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*dst++ = ((ch[2] & 0x03) << 6) | ch[3];
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}
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debug_return_size_t((size_t)(dst - dst0));
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}
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