iodine/src/base64.c
2012-02-04 20:33:58 +01:00

200 lines
4.3 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 "common.h"
#include "base64.h"
#define BLKSIZE_RAW 3
#define BLKSIZE_ENC 4
static const char cb64[] =
"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ-0123456789+";
static unsigned char rev64[128];
static int reverse_init = 0;
static int base64_encode(char *, size_t *, const void *, size_t);
static int base64_decode(void *, size_t *, const char *, size_t);
static int base64_handles_dots();
static int base64_blksize_raw();
static int base64_blksize_enc();
#define REV64(x) rev64[(int) (x)]
static struct encoder base64_encoder =
{
"Base64",
base64_encode,
base64_decode,
base64_handles_dots,
base64_handles_dots,
base64_blksize_raw,
base64_blksize_enc
};
struct encoder
*get_base64_encoder()
{
return &base64_encoder;
}
static int
base64_handles_dots()
{
return 0;
}
static int
base64_blksize_raw()
{
return BLKSIZE_RAW;
}
static int
base64_blksize_enc()
{
return BLKSIZE_ENC;
}
static int
base64_encode(char *buf, size_t *buflen, const void *data, size_t size)
{
size_t newsize;
size_t maxsize;
unsigned char c;
unsigned char *s;
unsigned char *p;
unsigned char *q;
int i;
memset(buf, 0, *buflen);
if (!reverse_init) {
for (i = 0; i < 64; i++) {
c = cb64[i];
rev64[(int) c] = i;
}
reverse_init = 1;
}
/* 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 = s = (unsigned char *) buf;
q = (unsigned char *)data;
for(i=0;i<size;i+=BLKSIZE_RAW) {
p[0] = cb64[((q[0] & 0xfc) >> 2)];
p[1] = cb64[(((q[0] & 0x03) << 4) | ((q[1] & 0xf0) >> 4))];
p[2] = (i+1 < size) ? cb64[((q[1] & 0x0f) << 2 ) | ((q[2] & 0xc0) >> 6)] : '\0';
p[3] = (i+2 < size) ? cb64[(q[2] & 0x3f)] : '\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
static int
decode_token(const unsigned char *t, unsigned char *data, size_t len)
{
if (len < 2)
return 0;
data[0] = ((REV64(t[0]) & 0x3f) << 2) |
((REV64(t[1]) & 0x30) >> 4);
if (len < 3)
return 1;
data[1] = ((REV64(t[1]) & 0x0f) << 4) |
((REV64(t[2]) & 0x3c) >> 2);
if (len < 4)
return 2;
data[2] = ((REV64(t[2]) & 0x03) << 6) |
(REV64(t[3]) & 0x3f);
return 3;
}
static int
base64_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;
unsigned char block[BLKSIZE_ENC];
int len;
int i;
if (!reverse_init) {
for (i = 0; i < 64; i++) {
c = cb64[i];
rev64[(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; p += BLKSIZE_ENC) {
/* since the str is const, we unescape in another buf */
for (i = 0; i < BLKSIZE_ENC; i++) {
block[i] = p[i];
}
len = decode_token(block, (unsigned char *) q, slen);
q += len;
slen -= BLKSIZE_ENC;
if (len < BLKSIZE_RAW)
break;
}
*q = '\0';
return q - (unsigned char *) buf;
}