unleashed-firmware/applications/external/totp/lib/base64/base64.c

72 lines
2.4 KiB
C

/*
* Base64 encoding/decoding (RFC1341)
* Copyright (c) 2005, Jouni Malinen <j@w1.fi>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Alternatively, this software may be distributed under the terms of BSD
* license.
*
*/
#include "base64.h"
#include <string.h>
static const uint8_t dtable[] = {0x3e, 0x80, 0x80, 0x80, 0x3f, 0x34, 0x35, 0x36, 0x37, 0x38,
0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x80, 0x80, 0x80, 0x0, 0x80,
0x80, 0x80, 0x0, 0x1, 0x2, 0x3, 0x4, 0x5, 0x6, 0x7,
0x8, 0x9, 0xa, 0xb, 0xc, 0xd, 0xe, 0xf, 0x10, 0x11,
0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x80, 0x80,
0x80, 0x80, 0x80, 0x80, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29,
0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33};
// "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static uint8_t get_dtable_value(uint8_t index) {
return (index < 43 || index > 122) ? 0x80 : dtable[index - 43];
}
uint8_t* base64_decode(const uint8_t* src, size_t len, size_t* out_len, size_t* out_size) {
uint8_t *out;
uint8_t *pos;
uint8_t in[4];
uint8_t block[4];
uint8_t tmp;
size_t i;
size_t count;
size_t olen;
count = 0;
for(i = 0; i < len; i++) {
if(get_dtable_value(src[i]) != 0x80) count++;
}
if(count == 0 || count % 4) return NULL;
olen = count / 4 * 3;
pos = out = malloc(olen);
*out_size = olen;
if(out == NULL) return NULL;
count = 0;
for(i = 0; i < len; i++) {
tmp = get_dtable_value(src[i]);
if(tmp == 0x80) continue;
in[count] = src[i];
block[count] = tmp;
count++;
if(count == 4) {
*pos++ = (block[0] << 2) | (block[1] >> 4);
*pos++ = (block[1] << 4) | (block[2] >> 2);
*pos++ = (block[2] << 6) | block[3];
count = 0;
}
}
if(pos > out) {
if(in[2] == '=')
pos -= 2;
else if(in[3] == '=')
pos--;
}
*out_len = pos - out;
return out;
}