145 lines
5.7 KiB
C
145 lines
5.7 KiB
C
/* *****************************************************************************
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* Description : BASE64 encoding and decoding
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* Date : 06-08-21 21:00
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* Author : aishen944
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* Copryright :
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********************************************************************************/
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#include <string.h>
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#include <stdlib.h>
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#include <errno.h>
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#include "base64.h"
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#define BASE64_PAD64 '='
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char base64_alphabet[] = {'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I',
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'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R',
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'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a',
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'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j',
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'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's',
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't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1',
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'2', '3', '4', '5', '6', '7', '8', '9', '+',
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'/'};
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char base64_suffix_map[256] = {
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255, 255, 255, 255, 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, 255, 255, 255, 255,
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255, 255, 255, 62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255, 255,
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255, 255, 255, 255, 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, 255, 26, 27, 28,
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29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48,
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49, 50, 51, 255, 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, 255, 255, 255, 255,
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255, 255, 255, 255, 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, 255, 255, 255, 255,
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255, 255, 255, 255, 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, 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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static char cmove_bits(unsigned char src, unsigned int lnum, unsigned int rnum) {
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src <<= lnum;
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src >>= rnum;
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return src;
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}
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*/
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#define cmove_bits(s, l, r) ((((s << (l)) & 0xFF) >> (r)) & 0xFF)
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//#define cmove_bits(s, l, r) (unsigned char)((unsigned char)((unsigned char)(s) << (unsigned int)(l)) >> (unsigned int)(r))
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int base64_encode(char *out, const char *data, int insize)
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{
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char *retpos;
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int m, padnum = 0, retsize, dlen = insize;
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if(dlen == 0) return 0;
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/* Account the result buffer size and alloc the memory for it. */
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if((dlen % 3) != 0)
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padnum = 3 - dlen % 3;
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retsize = (dlen + padnum) + ((dlen + padnum) * 1/3);
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if ( !out ) return retsize;
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retpos = out;
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/* Starting to convert the originality characters to BASE64 chracaters.
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Converting process keep to 4->6 principle. */
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for(m = 0; m < (dlen + padnum); m += 3) {
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/* When data is not suffice 24 bits then pad 0 and the empty place pad '='. */
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*(retpos) = base64_alphabet[cmove_bits(*data, 0, 2)];
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if(m == dlen + padnum - 3 && padnum != 0) { /* Whether the last bits-group suffice 24 bits. */
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if(padnum == 1) { /* 16bit need pad one '='. */
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*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2) + cmove_bits(*(data + 1), 0, 4)];
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*(retpos + 2) = base64_alphabet[cmove_bits(*(data + 1), 4, 2)];
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*(retpos + 3) = BASE64_PAD64;
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} else if(padnum == 2) { /* 8bit need pad two'='. */
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*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2)];
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*(retpos + 2) = BASE64_PAD64;
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*(retpos + 3) = BASE64_PAD64;
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}
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} else { /* 24bit normal. */
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*(retpos + 1) = base64_alphabet[cmove_bits(*data, 6, 2) + cmove_bits(*(data + 1), 0, 4)];
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*(retpos + 2) = base64_alphabet[cmove_bits(*(data + 1), 4, 2) + cmove_bits(*(data + 2), 0, 6)];
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*(retpos + 3) = base64_alphabet[*(data + 2) & 0x3f];
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}
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retpos += 4;
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data += 3;
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}
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return retsize;
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}
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int base64_decode(char *out, const char *bdata, int insize)
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{
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char *retpos;
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int m, padnum = 0, retsize = 0;
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if(insize == 0) return 0;
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if(insize % 4 != 0) return 0;
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/* Whether the data have invalid base-64 characters? */
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for(m = 0; m < insize; ++m) {
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if(bdata[m] != BASE64_PAD64 && (unsigned char)base64_suffix_map[bdata[m]] == 255)
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goto LEND;
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}
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/* Account the output size. */
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if(bdata[insize - 1] == '=') padnum = 1;
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if(bdata[insize - 1] == '=' && bdata[insize - 2] == '=') padnum = 2;
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retsize = (insize - 4) - (insize - 4) / 4 + (3 - padnum);
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if ( !out ) return retsize;
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retpos = out;
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/* Begging to decode. */
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for(m = 0; m < insize; m += 4) {
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*retpos = cmove_bits(base64_suffix_map[*bdata], 2, 0) + cmove_bits(base64_suffix_map[*(bdata + 1)], 0, 4);
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if(m == insize - 4 && padnum != 0) { /* Only deal with last four bits. */
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if(padnum == 1) /* Have one pad characters, only two availability characters. */
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*(retpos + 1) = cmove_bits(base64_suffix_map[*(bdata + 1)], 4, 0) + cmove_bits(base64_suffix_map[*(bdata + 2)], 0, 2);
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/*
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Have two pad characters, only two availability characters.
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if(padnum == 2) {
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}
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*/
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retpos += 3 - padnum;
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} else {
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*(retpos + 1) = cmove_bits(base64_suffix_map[*(bdata + 1)], 4, 0) + cmove_bits(base64_suffix_map[*(bdata + 2)], 0, 2);
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*(retpos + 2) = cmove_bits(base64_suffix_map[*(bdata + 2)], 6, 0) + base64_suffix_map[*(bdata + 3)];
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retpos += 3;
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}
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bdata += 4;
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}
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LEND: return retsize;
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}
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