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/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil; tab-width: 4 -*- */
/* vi: set expandtab shiftwidth=4 tabstop=4: */
/**
* \file
* <PRE>
* MODP_B64 - High performance base64 encoder/decoder
* Version 1.3 -- 17-Mar-2006
* http://modp.com/release/base64
*
* Copyright © 2005, 2006 Nick Galbreath -- nickg [at] modp [dot] com
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are
* met:
*
* Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 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.
*
* Neither the name of the modp.com 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 COPYRIGHT HOLDERS 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 COPYRIGHT
* OWNER 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.
*
* This is the standard "new" BSD license:
* http://www.opensource.org/licenses/bsd-license.php
* </PRE>
*/
/* public header */
#include "modp_b64.h"
#include "modp_b64_data.h"
#define BADCHAR 0x01FFFFFF
size_t modp_b64_encode_data(char* dest, const char* str, size_t len)
{
size_t i = 0;
uint8_t* p = (uint8_t*) dest;
/* unsigned here is important! */
uint8_t t1, t2, t3;
if (len > 2) {
for (; i < len - 2; i += 3) {
t1 = str[i]; t2 = str[i+1]; t3 = str[i+2];
*p++ = e0[t1];
*p++ = e1[((t1 & 0x03) << 4) | ((t2 >> 4) & 0x0F)];
*p++ = e1[((t2 & 0x0F) << 2) | ((t3 >> 6) & 0x03)];
*p++ = e2[t3];
}
}
switch (len - i) {
case 0:
break;
case 1:
t1 = str[i];
*p++ = e0[t1];
*p++ = e1[(t1 & 0x03) << 4];
*p++ = CHARPAD;
*p++ = CHARPAD;
break;
default: /* case 2 */
t1 = str[i]; t2 = str[i+1];
*p++ = e0[t1];
*p++ = e1[((t1 & 0x03) << 4) | ((t2 >> 4) & 0x0F)];
*p++ = e2[(t2 & 0x0F) << 2];
*p++ = CHARPAD;
}
return p - (uint8_t*)dest;
}
size_t modp_b64_encode(char* dest, const char* str, size_t len) {
size_t output_size = modp_b64_encode_data(dest, str, len);
dest[output_size] = '\0';
return output_size;
}
size_t do_decode_padding(const char* src, size_t len, ModpDecodePolicy policy) {
if (policy == ModpDecodePolicy::kNoPaddingValidation) {
while (len > 0 && src[len - 1] == CHARPAD) {
len--;
}
} else {
const size_t remainder = len % 4;
if (policy == ModpDecodePolicy::kStrict && (remainder != 0 || len < 4))
return MODP_B64_ERROR;
if (remainder == 0) {
if (src[len - 1] == CHARPAD) {
len--;
if (src[len - 1] == CHARPAD) {
len--;
}
}
}
}
return len % 4 == 1 ? MODP_B64_ERROR : len;
}
size_t modp_b64_decode(char* dest, const char* src, size_t len, ModpDecodePolicy policy)
{
if (len != 0)
len = do_decode_padding(src, len, policy);
if (len == 0 || len == MODP_B64_ERROR)
return len;
size_t i;
int leftover = len % 4;
size_t chunks = (leftover == 0) ? len / 4 - 1 : len /4;
uint8_t* p = (uint8_t*)dest;
uint32_t x = 0;
const uint8_t* y = (uint8_t*)src;
for (i = 0; i < chunks; ++i, y += 4) {
x = d0[y[0]] | d1[y[1]] | d2[y[2]] | d3[y[3]];
if (x >= BADCHAR) return MODP_B64_ERROR;
*p++ = ((uint8_t*)(&x))[0];
*p++ = ((uint8_t*)(&x))[1];
*p++ = ((uint8_t*)(&x))[2];
}
switch (leftover) {
case 0:
x = d0[y[0]] | d1[y[1]] | d2[y[2]] | d3[y[3]];
if (x >= BADCHAR) return MODP_B64_ERROR;
*p++ = ((uint8_t*)(&x))[0];
*p++ = ((uint8_t*)(&x))[1];
*p = ((uint8_t*)(&x))[2];
return (chunks+1)*3;
case 1: /* with padding this is an impossible case */
x = d0[y[0]];
*p = *((uint8_t*)(&x)); // i.e. first char/byte in int
break;
case 2: // * case 2, 1 output byte */
x = d0[y[0]] | d1[y[1]];
*p = *((uint8_t*)(&x)); // i.e. first char
break;
default: /* case 3, 2 output bytes */
x = d0[y[0]] | d1[y[1]] | d2[y[2]]; /* 0x3c */
*p++ = ((uint8_t*)(&x))[0];
*p = ((uint8_t*)(&x))[1];
break;
}
if (x >= BADCHAR) return MODP_B64_ERROR;
return 3*chunks + (6*leftover)/8;
}
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