327 lines
11 KiB
C
327 lines
11 KiB
C
/*
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* base64 - libubox base64 functions
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*
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* Copyright (C) 2015 Felix Fietkau <nbd@openwrt.org>
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*
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* Permission to use, copy, modify, and/or 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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/* $OpenBSD: base64.c,v 1.7 2013/12/31 02:32:56 tedu Exp $ */
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/*
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* Copyright (c) 1996 by Internet Software Consortium.
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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 INTERNET SOFTWARE CONSORTIUM DISCLAIMS
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* ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL INTERNET SOFTWARE
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* CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
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* DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
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* PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS
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* ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
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* SOFTWARE.
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*/
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/*
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* Portions Copyright (c) 1995 by International Business Machines, Inc.
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*
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* International Business Machines, Inc. (hereinafter called IBM) grants
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* permission under its copyrights to use, copy, modify, and distribute this
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* Software with or without fee, provided that the above copyright notice and
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* all paragraphs of this notice appear in all copies, and that the name of IBM
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* not be used in connection with the marketing of any product incorporating
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* the Software or modifications thereof, without specific, written prior
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* permission.
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*
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* To the extent it has a right to do so, IBM grants an immunity from suit
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* under its patents, if any, for the use, sale or manufacture of products to
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* the extent that such products are used for performing Domain Name System
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* dynamic updates in TCP/IP networks by means of the Software. No immunity is
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* granted for any product per se or for any other function of any product.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", AND IBM DISCLAIMS ALL WARRANTIES,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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* PARTICULAR PURPOSE. IN NO EVENT SHALL IBM BE LIABLE FOR ANY SPECIAL,
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* DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER ARISING
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* OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE, EVEN
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* IF IBM IS APPRISED OF THE POSSIBILITY OF SUCH DAMAGES.
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*/
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#include <sys/types.h>
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#include <ctype.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "utils.h"
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static const char Base64[] =
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"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
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static const char Pad64 = '=';
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/* (From RFC1521 and draft-ietf-dnssec-secext-03.txt)
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The following encoding technique is taken from RFC 1521 by Borenstein
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and Freed. It is reproduced here in a slightly edited form for
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convenience.
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A 65-character subset of US-ASCII is used, enabling 6 bits to be
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represented per printable character. (The extra 65th character, "=",
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is used to signify a special processing function.)
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The encoding process represents 24-bit groups of input bits as output
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strings of 4 encoded characters. Proceeding from left to right, a
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24-bit input group is formed by concatenating 3 8-bit input groups.
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These 24 bits are then treated as 4 concatenated 6-bit groups, each
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of which is translated into a single digit in the base64 alphabet.
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Each 6-bit group is used as an index into an array of 64 printable
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characters. The character referenced by the index is placed in the
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output string.
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Table 1: The Base64 Alphabet
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Value Encoding Value Encoding Value Encoding Value Encoding
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0 A 17 R 34 i 51 z
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1 B 18 S 35 j 52 0
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2 C 19 T 36 k 53 1
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3 D 20 U 37 l 54 2
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4 E 21 V 38 m 55 3
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5 F 22 W 39 n 56 4
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6 G 23 X 40 o 57 5
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7 H 24 Y 41 p 58 6
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8 I 25 Z 42 q 59 7
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9 J 26 a 43 r 60 8
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10 K 27 b 44 s 61 9
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11 L 28 c 45 t 62 +
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12 M 29 d 46 u 63 /
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13 N 30 e 47 v
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14 O 31 f 48 w (pad) =
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15 P 32 g 49 x
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16 Q 33 h 50 y
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Special processing is performed if fewer than 24 bits are available
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at the end of the data being encoded. A full encoding quantum is
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always completed at the end of a quantity. When fewer than 24 input
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bits are available in an input group, zero bits are added (on the
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right) to form an integral number of 6-bit groups. Padding at the
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end of the data is performed using the '=' character.
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Since all base64 input is an integral number of octets, only the
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-------------------------------------------------
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following cases can arise:
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(1) the final quantum of encoding input is an integral
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multiple of 24 bits; here, the final unit of encoded
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output will be an integral multiple of 4 characters
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with no "=" padding,
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(2) the final quantum of encoding input is exactly 8 bits;
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here, the final unit of encoded output will be two
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characters followed by two "=" padding characters, or
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(3) the final quantum of encoding input is exactly 16 bits;
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here, the final unit of encoded output will be three
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characters followed by one "=" padding character.
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*/
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int b64_encode(const void *_src, size_t srclength,
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void *dest, size_t targsize)
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{
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const unsigned char *src = _src;
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char *target = dest;
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size_t datalength = 0;
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u_char input[3] = {0};
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u_char output[4];
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int i;
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while (2 < srclength) {
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input[0] = *src++;
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input[1] = *src++;
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input[2] = *src++;
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srclength -= 3;
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output[0] = input[0] >> 2;
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output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
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output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
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output[3] = input[2] & 0x3f;
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if (datalength + 4 > targsize)
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return (-1);
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target[datalength++] = Base64[output[0]];
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target[datalength++] = Base64[output[1]];
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target[datalength++] = Base64[output[2]];
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target[datalength++] = Base64[output[3]];
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}
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/* Now we worry about padding. */
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if (0 != srclength) {
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/* Get what's left. */
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input[0] = input[1] = input[2] = '\0';
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for (i = 0; i < srclength; i++)
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input[i] = *src++;
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output[0] = input[0] >> 2;
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output[1] = ((input[0] & 0x03) << 4) + (input[1] >> 4);
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output[2] = ((input[1] & 0x0f) << 2) + (input[2] >> 6);
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if (datalength + 4 > targsize)
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return (-1);
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target[datalength++] = Base64[output[0]];
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target[datalength++] = Base64[output[1]];
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if (srclength == 1)
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target[datalength++] = Pad64;
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else
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target[datalength++] = Base64[output[2]];
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target[datalength++] = Pad64;
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}
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if (datalength >= targsize)
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return (-1);
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target[datalength] = '\0'; /* Returned value doesn't count \0. */
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return (datalength);
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}
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/* skips all whitespace anywhere.
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converts characters, four at a time, starting at (or after)
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src from base - 64 numbers into three 8 bit bytes in the target area.
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it returns the number of data bytes stored at the target, or -1 on error.
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*/
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int b64_decode(const void *_src, void *dest, size_t targsize)
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{
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const char *src = _src;
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unsigned char *target = dest;
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int tarindex, state, ch;
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u_char nextbyte;
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char *pos;
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state = 0;
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tarindex = 0;
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while ((ch = (unsigned char)*src++) != '\0') {
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if (isspace(ch)) /* Skip whitespace anywhere. */
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continue;
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if (ch == Pad64)
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break;
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pos = strchr(Base64, ch);
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if (pos == 0) /* A non-base64 character. */
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return (-1);
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switch (state) {
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case 0:
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if (target) {
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if (tarindex >= targsize)
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return (-1);
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target[tarindex] = (pos - Base64) << 2;
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}
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state = 1;
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break;
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case 1:
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if (target) {
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if (tarindex >= targsize)
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return (-1);
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target[tarindex] |= (pos - Base64) >> 4;
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nextbyte = ((pos - Base64) & 0x0f) << 4;
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if (tarindex + 1 < targsize)
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target[tarindex+1] = nextbyte;
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else if (nextbyte)
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return (-1);
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}
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tarindex++;
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state = 2;
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break;
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case 2:
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if (target) {
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if (tarindex >= targsize)
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return (-1);
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target[tarindex] |= (pos - Base64) >> 2;
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nextbyte = ((pos - Base64) & 0x03) << 6;
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if (tarindex + 1 < targsize)
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target[tarindex+1] = nextbyte;
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else if (nextbyte)
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return (-1);
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}
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tarindex++;
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state = 3;
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break;
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case 3:
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if (target) {
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if (tarindex >= targsize)
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return (-1);
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target[tarindex] |= (pos - Base64);
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}
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tarindex++;
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state = 0;
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break;
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}
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}
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/*
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* We are done decoding Base-64 chars. Let's see if we ended
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* on a byte boundary, and/or with erroneous trailing characters.
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*/
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if (ch == Pad64) { /* We got a pad char. */
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ch = (unsigned char)*src++; /* Skip it, get next. */
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switch (state) {
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case 0: /* Invalid = in first position */
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case 1: /* Invalid = in second position */
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return (-1);
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case 2: /* Valid, means one byte of info */
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/* Skip any number of spaces. */
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for (; ch != '\0'; ch = (unsigned char)*src++)
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if (!isspace(ch))
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break;
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/* Make sure there is another trailing = sign. */
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if (ch != Pad64)
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return (-1);
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ch = (unsigned char)*src++; /* Skip the = */
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/* Fall through to "single trailing =" case. */
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/* FALLTHROUGH */
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case 3: /* Valid, means two bytes of info */
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/*
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* We know this char is an =. Is there anything but
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* whitespace after it?
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*/
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for (; ch != '\0'; ch = (unsigned char)*src++)
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if (!isspace(ch))
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return (-1);
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/*
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* Now make sure for cases 2 and 3 that the "extra"
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* bits that slopped past the last full byte were
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* zeros. If we don't check them, they become a
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* subliminal channel.
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*/
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if (target && tarindex < targsize &&
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target[tarindex] != 0)
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return (-1);
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}
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} else {
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/*
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* We ended by seeing the end of the string. Make sure we
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* have no partial bytes lying around.
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*/
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if (state != 0)
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return (-1);
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}
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/* Null-terminate if we have room left */
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if (tarindex < targsize)
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target[tarindex] = 0;
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return (tarindex);
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}
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