/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/* util/support/base64.c - base64 encoder and decoder */
/*
* Copyright (c) 1995-2001 Kungliga Tekniska Högskolan
* (Royal Institute of Technology, Stockholm, Sweden).
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#include <k5-platform.h>
#include <k5-base64.h>
static const char base64_chars[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char *
k5_base64_encode(const void *data, size_t len)
{
char *s, *p;
size_t i;
unsigned int c;
const unsigned char *q;
if (len > SIZE_MAX / 4)
return NULL;
p = s = malloc(len * 4 / 3 + 4);
if (p == NULL)
return NULL;
q = (const unsigned char *)data;
for (i = 0; i < len;) {
c = q[i++];
c *= 256;
if (i < len)
c += q[i];
i++;
c *= 256;
if (i < len)
c += q[i];
i++;
p[0] = base64_chars[(c & 0x00fc0000) >> 18];
p[1] = base64_chars[(c & 0x0003f000) >> 12];
p[2] = base64_chars[(c & 0x00000fc0) >> 6];
p[3] = base64_chars[(c & 0x0000003f) >> 0];
if (i > len)
p[3] = '=';
if (i > len + 1)
p[2] = '=';
p += 4;
}
*p = '\0';
return s;
}
#define DECODE_ERROR 0xffffffff
/* Decode token, which must be four bytes long. */
static unsigned int
decode_token(const char *token)
{
int i, marker = 0;
unsigned int val = 0;
const char *p;
for (i = 0; i < 4; i++) {
val *= 64;
if (token[i] == '=') {
marker++;
} else if (marker > 0) {
return DECODE_ERROR;
} else {
p = strchr(base64_chars, token[i]);
if (p == NULL)
return DECODE_ERROR;
val += p - base64_chars;
}
}
if (marker > 2)
return DECODE_ERROR;
return (marker << 24) | val;
}
void *
k5_base64_decode(const char *str, size_t *len_out)
{
unsigned char *data, *q;
unsigned int val, marker;
size_t len;
*len_out = SIZE_MAX;
/* Allocate the output buffer. */
len = strlen(str);
if (len % 4)
return NULL;
q = data = malloc(len / 4 * 3);
if (data == NULL) {
*len_out = 0;
return NULL;
}
/* Decode the string. */
for (; *str != '\0'; str += 4) {
val = decode_token(str);
if (val == DECODE_ERROR) {
free(data);
return NULL;
}
marker = (val >> 24) & 0xff;
*q++ = (val >> 16) & 0xff;
if (marker < 2)
*q++ = (val >> 8) & 0xff;
if (marker < 1)
*q++ = val & 0xff;
}
*len_out = q - data;
return data;
}