iodine/src/base32.c
Ralf Ramsauer 4591cafd27 encoding: simplify {places,eats}_dots
Why not using constant bools?

Much simpler than complex function calls, that eventually return
constant values.

Signed-off-by: Ralf Ramsauer <ralf@ramses-pyramidenbau.de>
2017-03-11 21:30:50 -08:00

239 lines
6.2 KiB
C

/*
* Copyright (c) 2006-2014 Erik Ekman <yarrick@kryo.se>,
* 2006-2009 Bjorn Andersson <flex@kryo.se>
* Mostly rewritten 2009 J.A.Bezemer@opensourcepartners.nl
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "encoding.h"
#define BASE32_BLKSIZE_RAW 5
#define BASE32_BLKSIZE_ENC 8
static const char cb32[] =
"abcdefghijklmnopqrstuvwxyz012345";
static const char cb32_ucase[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ012345";
static unsigned char rev32[256];
static int reverse_init = 0;
inline static void base32_reverse_init(void)
{
int i;
unsigned char c;
if (!reverse_init) {
memset (rev32, 0, 256);
for (i = 0; i < 32; i++) {
c = cb32[i];
rev32[(int) c] = i;
c = cb32_ucase[i];
rev32[(int) c] = i;
}
reverse_init = 1;
}
}
int b32_5to8(int in)
{
return cb32[in & 31];
}
int b32_8to5(int in)
{
base32_reverse_init();
return rev32[in];
}
/*
* Fills *buf with max. *buflen characters, encoding size bytes of *data.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold the trailing '\0'.
*
* return value : #bytes filled in buf (excluding \0)
* sets *buflen to : #bytes encoded from data
*/
static int base32_encode(char *buf, size_t *buflen, const void *data, size_t size)
{
unsigned char *udata = (unsigned char *) data;
int iout = 0; /* to-be-filled output char */
int iin = 0; /* one more than last input byte that can be
successfully decoded */
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0xf8) >> 3)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
buf[iout] = cb32[((udata[iin] & 0x07) << 2) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xc0) >> 6) : 0)];
iin++; /* 0 complete, iin=1 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x3e) >> 1)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
buf[iout] = cb32[((udata[iin] & 0x01) << 4) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xf0) >> 4) : 0)];
iin++; /* 1 complete, iin=2 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x0f) << 1) |
((iin + 1 < size) ?
((udata[iin + 1] & 0x80) >> 7) : 0)];
iin++; /* 2 complete, iin=3 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x7c) >> 2)];
iout++;
if (iout >= *buflen || iin >= size) {
iout--; /* previous char is useless */
break;
}
buf[iout] = cb32[((udata[iin] & 0x03) << 3) |
((iin + 1 < size) ?
((udata[iin + 1] & 0xe0) >> 5) : 0)];
iin++; /* 3 complete, iin=4 */
iout++;
if (iout >= *buflen || iin >= size)
break;
buf[iout] = cb32[((udata[iin] & 0x1f))];
iin++; /* 4 complete, iin=5 */
iout++;
}
buf[iout] = '\0';
/* store number of bytes from data that was used */
*buflen = iin;
return iout;
}
#define REV32(x) rev32[(int) (x)]
/*
* Fills *buf with max. *buflen bytes, decoded from slen chars in *str.
* Decoding stops early when *str contains \0.
* Illegal encoded chars are assumed to decode to zero.
*
* NOTE: *buf space should be at least 1 byte _more_ than *buflen
* to hold a trailing '\0' that is added (though *buf will usually
* contain full-binary data).
*
* return value : #bytes filled in buf (excluding \0)
*/
static int base32_decode(void *buf, size_t *buflen, const char *str,
size_t slen)
{
unsigned char *ubuf = (unsigned char *) buf;
int iout = 0; /* to-be-filled output byte */
int iin = 0; /* next input char to use in decoding */
base32_reverse_init ();
/* Note: Don't bother to optimize manually. GCC optimizes
better(!) when using simplistic array indexing. */
while (1) {
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x1f) << 3) |
((REV32(str[iin + 1]) & 0x1c) >> 2);
iin++; /* 0 used up, iin=1 */
iout++;
if (iout >= *buflen || iin + 2 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0' ||
str[iin + 2] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x03) << 6) |
((REV32(str[iin + 1]) & 0x1f) << 1) |
((REV32(str[iin + 2]) & 0x10) >> 4);
iin += 2; /* 1,2 used up, iin=3 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x0f) << 4) |
((REV32(str[iin + 1]) & 0x1e) >> 1);
iin++; /* 3 used up, iin=4 */
iout++;
if (iout >= *buflen || iin + 2 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0' ||
str[iin + 2] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x01) << 7) |
((REV32(str[iin + 1]) & 0x1f) << 2) |
((REV32(str[iin + 2]) & 0x18) >> 3);
iin += 2; /* 4,5 used up, iin=6 */
iout++;
if (iout >= *buflen || iin + 1 >= slen ||
str[iin] == '\0' || str[iin + 1] == '\0')
break;
ubuf[iout] = ((REV32(str[iin]) & 0x07) << 5) |
((REV32(str[iin + 1]) & 0x1f));
iin += 2; /* 6,7 used up, iin=8 */
iout++;
}
ubuf[iout] = '\0';
return iout;
}
const struct encoder base32_ops = {
.name = "Base32",
.encode = base32_encode,
.decode = base32_decode,
.places_dots = false,
.eats_dots = false,
.blocksize_raw = BASE32_BLKSIZE_RAW,
.blocksize_encoded = BASE32_BLKSIZE_ENC,
};