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/*
This file is part of msr.
msr is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
msr is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
You should have received a copy of the GNU General Public License
along with Foobar. If not, see <http://www.gnu.org/licenses/>.
*/
#include "base64.h"
static const char b64padchar = (uint8_t)'=';
static const char b64chars[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/*
;; Precompute inverse lookup with skippable stuff and padding
(insert
(apply #'concat
(let ((str "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/")
(skip " \t\n\r") (skipnum 65)
(pad ?=) (padnum 64) (invalidnum 66))
(cl-loop for k from 0 to 255
for j = (let* ((s (char-to-string k))
(v (s-index-of s str))
(w (s-index-of s skip))
(x (char-equal k pad)))
(if v (format "%2dU " v)
(if w "SKIP"
(if x "PADD" "INVD"))))
collect (concat ", " j)))))
*/
#define INVD (uint8_t)66
#define SKIP (uint8_t)65
#define PADD (uint8_t)64
static const uint8_t b64inverse[256] = {
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, SKIP, SKIP, INVD, INVD, SKIP, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
SKIP, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, 62 , INVD, INVD, INVD, 63 ,
52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , INVD, INVD, INVD, PADD, INVD, INVD,
INVD, 0 , 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ,
15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , INVD, INVD, INVD, INVD, INVD,
INVD, 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 ,
41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD,
INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD, INVD
};
Error bin_to_base64(uint8_t const * const bin, size_t binlen,
uint8_t *out, size_t maxoutsize, size_t *outlen) {
if ((*outlen = 4*(binlen/3)+4) > maxoutsize) return E_SMALL_BUFF;
size_t k, l;
uint32_t n = 0;
// Look at floor(binlen/3) groups of three bytes
for (k=0, l=0; k<binlen/3; k++) {
n = ((uint32_t)bin[3*k])<<16;
n |= ((uint32_t)bin[3*k+1])<<8;
n |= ((uint32_t)bin[3*k+2]);
out[l++] = b64chars[(n>>18)&63];
out[l++] = b64chars[(n>>12)&63];
out[l++] = b64chars[(n>>6)&63];
out[l++] = b64chars[n&63];
}
// What is the actual index in bin?
k *= 3;
// Now deal with remainders
if (k<binlen) {
n = ((uint32_t)bin[k])<<16;
out[l+3] = b64padchar;
if (k+1<binlen) {
n |= ((uint32_t)bin[k+1])<<8;
out[l+2] = b64chars[(n>>6)&63];
} else out[l+2] = b64padchar;
out[l] = b64chars[(n>>18)&63];
out[l+1] = b64chars[(n>>12)&63];
l+=4;
};
out[l]=0;
return SUCCESS;
}
// Note: will read first valid b64 encoded string and stop caring
Error base64_to_bin(uint8_t const * const str, size_t strlen,
uint8_t *buf, size_t bufmaxsize, size_t *buflen) {
if (str == NULL) return E_NULL;
*buflen = 0;
size_t k = 0;
uint8_t c = 0;
uint32_t t = 0;
while(k<strlen) {
uint8_t l = b64inverse[str[k++]];
switch (l) {
// Skip = Skip, a universal truth
case SKIP: break;
// We don't take these transgressions lightly
case INVD: return E_B64_BAD_STR;
// Annoying validity checks here
case PADD: {
if (c<2) return E_B64_BAD_STR;
// If we have only consumed 2/4 chars, then there must be 2 x pad || .* || eof
if (c==2 && ( str[k]!=b64padchar))
return E_B64_BAD_STR;
k = strlen;
// If we have 3/4 chars, pad || .* || eof
break;
}
// A valid b64 char (not incl. padding)
default: {
// Store these six bits
t = (t<<6) | l;
// If we've done this four times, then output three bytes
if (++c > 3) {
if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
buf[(*buflen)++] = (uint8_t)((t>>16)&255);
if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
buf[(*buflen)++] = (uint8_t)((t>>8)&255);
if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
buf[(*buflen)++] = (uint8_t)(t&255);
c = t = 0;
}
}
}
}
// This should not happen
if (c==1) return E_B64_BAD_STR;
// Finish up, c=2 => 1 byte, c=3 => 2 bytes
else if (c==2) {
if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
buf[(*buflen)++] = (uint8_t)((t>>4)&255);
}
else if (c==3) {
if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
buf[(*buflen)++] = (uint8_t)((t>>10)&255);
if ((*buflen)>=bufmaxsize) return E_SMALL_BUFF;
buf[(*buflen)++] = (uint8_t)((t>>2)&255);
}
// done
return SUCCESS;
}
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