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sudo-project
GitHub Repository: sudo-project/sudo
 Path: blob/main/lib/util/b64_decode.c
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/*

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 * SPDX-License-Identifier: ISC

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 *

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 * Copyright (c) 2013-2018 Todd C. Miller <[email protected]>

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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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 */

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#include <config.h>

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#include <sudo_compat.h>

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#include <sudo_debug.h>

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#include <sudo_util.h>

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/*

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 * Derived from code with the following declaration:

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 *	PUBLIC DOMAIN - Jon Mayo - November 13, 2003 

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 */

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static const unsigned char base64dec_tab[256]= {

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255, 62,255,255,255, 63,

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     52, 53, 54, 55, 56, 57, 58, 59, 60, 61,255,255,255,  0,255,255,

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    255,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,

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     15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,255,255,255,255,255,

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    255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,

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     41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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    255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,

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};

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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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sudo_base64_decode_v1(const char * restrict in, unsigned char * restrict out,

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    size_t out_size)

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{

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    unsigned char *out_end = out + out_size;

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    const unsigned char *out0 = out;

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    unsigned int rem, v;

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    debug_decl(sudo_base64_decode, SUDO_DEBUG_UTIL);

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    for (v = 0, rem = 0; *in != '\0' && *in != '='; in++) {

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	unsigned char ch = base64dec_tab[(unsigned char)*in];

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	if (ch == 255)

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	    debug_return_size_t((size_t)-1);

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	v = (v << 6) | ch;

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	rem += 6;

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	if (rem >= 8) {

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	    rem -= 8;

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	    if (out >= out_end)

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		debug_return_size_t((size_t)-1);

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	    *out++ = (v >> rem) & 0xff;

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	}

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    }

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    if (rem >= 8) {

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	    if (out >= out_end)

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		debug_return_size_t((size_t)-1);

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	    *out++ = (v >> rem) & 0xff;

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    }

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    debug_return_size_t((size_t)(out - out0));

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}

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