branch: master
base64.c
7814 bytesRaw
/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) Daniel Stenberg, <daniel@haxx.se>, et al.
*
* This software is licensed as described in the file COPYING, which
* you should have received as part of this distribution. The terms
* are also available at https://curl.se/docs/copyright.html.
*
* You may opt to use, copy, modify, merge, publish, distribute and/or sell
* copies of the Software, and permit persons to whom the Software is
* furnished to do so, under the terms of the COPYING file.
*
* This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
* KIND, either express or implied.
*
* SPDX-License-Identifier: curl
*
***************************************************************************/
/* Base64 encoding/decoding */
#include "curl_setup.h"
#include "curlx/base64.h"
/* ---- Base64 Encoding/Decoding Table --- */
const char curlx_base64encdec[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/* The Base 64 encoding with a URL and filename safe alphabet, RFC 4648
section 5 */
static const char base64url[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
static const unsigned char decodetable[] = {
62, 255, 255, 255, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 255,
255, 255, 255, 255, 255, 255, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25,
255, 255, 255, 255, 255, 255, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
};
/*
* curlx_base64_decode()
*
* Given a base64 null-terminated string at src, decode it and return a
* pointer in *outptr to a newly allocated memory area holding decoded data.
* Size of decoded data is returned in variable pointed by outlen.
*
* Returns CURLE_OK on success, otherwise specific error code. Function
* output shall not be considered valid unless CURLE_OK is returned.
*
* When decoded data length is 0, returns NULL in *outptr.
*
* @unittest: 1302
*/
CURLcode curlx_base64_decode(const char *src,
uint8_t **outptr, size_t *outlen)
{
size_t srclen = 0;
size_t padding = 0;
size_t i;
size_t numQuantums;
size_t fullQuantums;
size_t rawlen = 0;
unsigned char *pos;
unsigned char *newstr;
unsigned char lookup[256];
*outptr = NULL;
*outlen = 0;
srclen = strlen(src);
/* Check the length of the input string is valid */
if(!srclen || srclen % 4)
return CURLE_BAD_CONTENT_ENCODING;
/* srclen is at least 4 here */
while(src[srclen - 1 - padding] == '=') {
/* count padding characters */
padding++;
/* A maximum of two = padding characters is allowed */
if(padding > 2)
return CURLE_BAD_CONTENT_ENCODING;
}
/* Calculate the number of quantums */
numQuantums = srclen / 4;
fullQuantums = numQuantums - (padding ? 1 : 0);
/* Calculate the size of the decoded string */
rawlen = (numQuantums * 3) - padding;
/* Allocate our buffer including room for a null-terminator */
newstr = curlx_malloc(rawlen + 1);
if(!newstr)
return CURLE_OUT_OF_MEMORY;
pos = newstr;
memset(lookup, 0xff, sizeof(lookup));
memcpy(&lookup['+'], decodetable, sizeof(decodetable));
/* Decode the complete quantums first */
for(i = 0; i < fullQuantums; i++) {
unsigned char val;
unsigned int x = 0;
int j;
for(j = 0; j < 4; j++) {
val = lookup[(unsigned char)*src++];
if(val == 0xff) /* bad symbol */
goto bad;
x = (x << 6) | val;
}
pos[2] = x & 0xff;
pos[1] = (x >> 8) & 0xff;
pos[0] = (x >> 16) & 0xff;
pos += 3;
}
if(padding) {
/* this means either 8 or 16 bits output */
unsigned char val;
unsigned int x = 0;
int j;
size_t padc = 0;
for(j = 0; j < 4; j++) {
if(*src == '=') {
x <<= 6;
src++;
if(++padc > padding)
/* this is a badly placed '=' symbol! */
goto bad;
}
else {
val = lookup[(unsigned char)*src++];
if(val == 0xff) /* bad symbol */
goto bad;
x = (x << 6) | val;
}
}
if(padding == 1)
pos[1] = (x >> 8) & 0xff;
pos[0] = (x >> 16) & 0xff;
pos += 3 - padding;
}
/* Null-terminate */
*pos = '\0';
/* Return the decoded data */
*outptr = newstr;
*outlen = rawlen;
return CURLE_OK;
bad:
curlx_free(newstr);
return CURLE_BAD_CONTENT_ENCODING;
}
static CURLcode base64_encode(const char *table64,
uint8_t padbyte,
const uint8_t *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
char *output;
char *base64data;
const unsigned char *in = (const unsigned char *)inputbuff;
*outptr = NULL;
*outlen = 0;
if(!insize)
return CURLE_OK;
/* safety precaution */
DEBUGASSERT(insize <= CURL_MAX_BASE64_INPUT);
if(insize > CURL_MAX_BASE64_INPUT)
return CURLE_TOO_LARGE;
base64data = output = curlx_malloc(((insize + 2) / 3 * 4) + 1);
if(!output)
return CURLE_OUT_OF_MEMORY;
while(insize >= 3) {
*output++ = table64[in[0] >> 2];
*output++ = table64[((in[0] & 0x03) << 4) | (in[1] >> 4)];
*output++ = table64[((in[1] & 0x0F) << 2) | ((in[2] & 0xC0) >> 6)];
*output++ = table64[in[2] & 0x3F];
insize -= 3;
in += 3;
}
if(insize) {
/* this is only one or two bytes now */
*output++ = table64[in[0] >> 2];
if(insize == 1) {
*output++ = table64[((in[0] & 0x03) << 4)];
if(padbyte) {
*output++ = padbyte;
*output++ = padbyte;
}
}
else {
/* insize == 2 */
*output++ = table64[((in[0] & 0x03) << 4) | ((in[1] & 0xF0) >> 4)];
*output++ = table64[((in[1] & 0x0F) << 2)];
if(padbyte)
*output++ = padbyte;
}
}
/* Null-terminate */
*output = '\0';
/* Return the pointer to the new data (allocated memory) */
*outptr = base64data;
/* Return the length of the new data */
*outlen = (size_t)(output - base64data);
return CURLE_OK;
}
/*
* curlx_base64_encode()
*
* Given a pointer to an input buffer and an input size, encode it and
* return a pointer in *outptr to a newly allocated memory area holding
* encoded data. Size of encoded data is returned in variable pointed by
* outlen.
*
* Returns CURLE_OK on success, otherwise specific error code. Function
* output shall not be considered valid unless CURLE_OK is returned.
*
* @unittest: 1302
*/
CURLcode curlx_base64_encode(const uint8_t *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
return base64_encode(curlx_base64encdec, '=',
inputbuff, insize, outptr, outlen);
}
/*
* curlx_base64url_encode()
*
* Given a pointer to an input buffer and an input size, encode it and
* return a pointer in *outptr to a newly allocated memory area holding
* encoded data. Size of encoded data is returned in variable pointed by
* outlen.
*
* Input length of 0 indicates input buffer holds a null-terminated string.
*
* Returns CURLE_OK on success, otherwise specific error code. Function
* output shall not be considered valid unless CURLE_OK is returned.
*
* @unittest: 1302
*/
CURLcode curlx_base64url_encode(const uint8_t *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
return base64_encode(base64url, 0, inputbuff, insize, outptr, outlen);
}