77 lines
2.3 KiB
C
77 lines
2.3 KiB
C
/* ----------------------------------------------------------------------- *
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*
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* Copyright 2005-2008 H. Peter Anvin - All Rights Reserved
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*
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* Permission is hereby granted, free of charge, to any person
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* obtaining a copy of this software and associated documentation
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* files (the "Software"), to deal in the Software without
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* restriction, including without limitation the rights to use,
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* copy, modify, merge, publish, distribute, sublicense, and/or
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* sell copies of the Software, and to permit persons to whom
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* the Software is furnished to do so, subject to the following
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* conditions:
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*
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* The above copyright notice and this permission notice shall
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* be included in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
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* OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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* HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
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* WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
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* FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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* OTHER DEALINGS IN THE SOFTWARE.
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*
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* ----------------------------------------------------------------------- */
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/*
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* unbase64.c
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*
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* Convert a string in base64 format to a byte array.
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*/
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#include <string.h>
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#include <base64.h>
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static const unsigned char _base64chars[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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size_t unbase64(unsigned char *buffer, size_t bufsiz, const char *txt)
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{
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unsigned int bits = 0;
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int nbits = 0;
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char base64tbl[256];
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int i;
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char v;
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size_t nbytes = 0;
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memset(base64tbl, -1, sizeof base64tbl);
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for (i = 0; _base64chars[i]; i++) {
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base64tbl[_base64chars[i]] = i;
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}
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/* Also support filesystem safe alternate base64 encoding */
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base64tbl['.'] = 62;
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base64tbl['-'] = 62;
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base64tbl['_'] = 63;
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while (*txt) {
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if ((v = base64tbl[(unsigned char)*txt]) >= 0) {
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bits <<= 6;
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bits += v;
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nbits += 6;
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if (nbits >= 8) {
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if (nbytes < bufsiz)
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*buffer++ = (bits >> (nbits - 8));
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nbytes++;
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nbits -= 8;
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}
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}
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txt++;
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}
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return nbytes;
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}
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