iodine/src/base32.c

221 lines
4.7 KiB
C

/*
* Copyright (c) 2006-2008 Bjorn Andersson <flex@kryo.se>, Erik Ekman <yarrick@kryo.se>
*
* Permission to use, copy, modify, and 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"
#include "base32.h"
#define BLKSIZE_RAW 5
#define BLKSIZE_ENC 8
static const char cb32[] =
"abcdefghijklmnopqrstuvwxyz012345";
static unsigned char rev32[128];
static int reverse_init = 0;
static int base32_decode(void *, size_t *, const char *, size_t);
static int base32_encode(char *, size_t *, const void *, size_t);
static int base32_handles_dots();
static int base32_blksize_raw();
static int base32_blksize_enc();
static struct encoder base32_encoder =
{
"Base32",
base32_encode,
base32_decode,
base32_handles_dots,
base32_handles_dots,
base32_blksize_raw,
base32_blksize_enc
};
struct encoder
*get_base32_encoder()
{
return &base32_encoder;
}
static int
base32_handles_dots()
{
return 0;
}
static int
base32_blksize_raw()
{
return BLKSIZE_RAW;
}
static int
base32_blksize_enc()
{
return BLKSIZE_ENC;
}
int
b32_5to8(int in)
{
return cb32[in & 31];
}
int
b32_8to5(int in)
{
int i;
int c;
if (!reverse_init) {
for (i = 0; i < 32; i++) {
c = cb32[i];
rev32[(int) c] = i;
}
reverse_init = 1;
}
return rev32[in];
}
static int
base32_encode(char *buf, size_t *buflen, const void *data, size_t size)
{
size_t newsize;
size_t maxsize;
unsigned char *p;
unsigned char *q;
int i;
memset(buf, 0, *buflen);
/* how many chars can we encode within the buf */
maxsize = BLKSIZE_RAW * (*buflen / BLKSIZE_ENC - 1) - 1;
/* how big will the encoded data be */
newsize = BLKSIZE_ENC * (size / BLKSIZE_RAW + 1) + 1;
/* if the buffer is too small, eat some of the data */
if (*buflen < newsize) {
size = maxsize;
}
p = (unsigned char *) buf;
q = (unsigned char *)data;
for(i=0;i<size;i+=BLKSIZE_RAW) {
p[0] = cb32[((q[0] & 0xf8) >> 3)];
p[1] = cb32[(((q[0] & 0x07) << 2) | ((q[1] & 0xc0) >> 6))];
p[2] = (i+1 < size) ? cb32[((q[1] & 0x3e) >> 1)] : '\0';
p[3] = (i+1 < size) ? cb32[((q[1] & 0x01) << 4) | ((q[2] & 0xf0) >> 4)] : '\0';
p[4] = (i+2 < size) ? cb32[((q[2] & 0x0f) << 1) | ((q[3] & 0x80) >> 7)] : '\0';
p[5] = (i+3 < size) ? cb32[((q[3] & 0x7c) >> 2)] : '\0';
p[6] = (i+3 < size) ? cb32[((q[3] & 0x03) << 3) | ((q[4] & 0xe0) >> 5)] : '\0';
p[7] = (i+4 < size) ? cb32[((q[4] & 0x1f))] : '\0';
q += BLKSIZE_RAW;
p += BLKSIZE_ENC;
}
*p = 0;
/* store number of bytes from data that was used */
*buflen = size;
return strlen(buf) - 1;
}
#define DECODE_ERROR 0xffffffff
#define REV32(x) rev32[(int) (x)]
static int
decode_token(const unsigned char *t, unsigned char *data, size_t len)
{
if (len < 2)
return 0;
data[0] = ((REV32(t[0]) & 0x1f) << 3) |
((REV32(t[1]) & 0x1c) >> 2);
if (len < 4)
return 1;
data[1] = ((REV32(t[1]) & 0x03) << 6) |
((REV32(t[2]) & 0x1f) << 1) |
((REV32(t[3]) & 0x10) >> 4);
if (len < 5)
return 2;
data[2] = ((REV32(t[3]) & 0x0f) << 4) |
((REV32(t[4]) & 0x1e) >> 1);
if (len < 7)
return 3;
data[3] = ((REV32(t[4]) & 0x01) << 7) |
((REV32(t[5]) & 0x1f) << 2) |
((REV32(t[6]) & 0x18) >> 3);
if (len < 8)
return 4;
data[4] = ((REV32(t[6]) & 0x07) << 5) |
((REV32(t[7]) & 0x1f));
return 5;
}
static int
base32_decode(void *buf, size_t *buflen, const char *str, size_t slen)
{
unsigned char *q;
size_t newsize;
size_t maxsize;
const char *p;
unsigned char c;
int len;
int i;
if (!reverse_init) {
for (i = 0; i < 32; i++) {
c = cb32[i];
rev32[(int) c] = i;
}
reverse_init = 1;
}
/* chars needed to decode slen */
newsize = BLKSIZE_RAW * (slen / BLKSIZE_ENC + 1) + 1;
/* encoded chars that fit in buf */
maxsize = BLKSIZE_ENC * (*buflen / BLKSIZE_RAW + 1) + 1;
/* if the buffer is too small, eat some of the data */
if (*buflen < newsize) {
slen = maxsize;
}
q = buf;
for (p = str; *p && strchr(cb32, *p); p += BLKSIZE_ENC) {
len = decode_token((unsigned char *) p, (unsigned char *) q, slen);
q += len;
slen -= BLKSIZE_ENC;
if (len < BLKSIZE_RAW)
break;
}
*q = '\0';
return q - (unsigned char *) buf;
}