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curl/lib/base64.c
Yang Tse fd00b382b2 base64: fix Curl_base64_encode and Curl_base64_decode interfaces
Previous interfaces for these libcurl internal functions did not allow to tell
apart a legitimate zero size result from an error condition. These functions
now return a CURLcode indicating function success or otherwise specific error.
Output size is returned using a pointer argument.

All usage of these two functions, and others closely related, has been adapted
to the new interfaces. Relative error and OOM handling adapted or added where
missing. Unit test 1302 also adapted.
2011-08-24 08:10:30 +02:00

249 lines
6.7 KiB
C

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2011, 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 http://curl.haxx.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.
*
***************************************************************************/
/* Base64 encoding/decoding */
#include "setup.h"
#define _MPRINTF_REPLACE /* use our functions only */
#include <curl/mprintf.h>
#include "urldata.h" /* for the SessionHandle definition */
#include "warnless.h"
#include "curl_base64.h"
#include "curl_memory.h"
#include "non-ascii.h"
/* include memdebug.h last */
#include "memdebug.h"
/* ---- Base64 Encoding/Decoding Table --- */
static const char table64[]=
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
static void decodeQuantum(unsigned char *dest, const char *src)
{
const char *s, *p;
unsigned long i, v, x = 0;
for(i = 0, s = src; i < 4; i++, s++) {
v = 0;
p = table64;
while(*p && (*p != *s)) {
v++;
p++;
}
if(*p == *s)
x = (x << 6) + v;
else if(*s == '=')
x = (x << 6);
}
dest[2] = curlx_ultouc(x);
x >>= 8;
dest[1] = curlx_ultouc(x);
x >>= 8;
dest[0] = curlx_ultouc(x);
}
/*
* Curl_base64_decode()
*
* Given a base64 NUL-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 Curl_base64_decode(const char *src,
unsigned char **outptr, size_t *outlen)
{
size_t length = 0;
size_t equalsTerm = 0;
size_t i;
size_t numQuantums;
unsigned char lastQuantum[3];
size_t rawlen = 0;
unsigned char *newstr;
*outptr = NULL;
*outlen = 0;
while((src[length] != '=') && src[length])
length++;
/* A maximum of two = padding characters is allowed */
if(src[length] == '=') {
equalsTerm++;
if(src[length+equalsTerm] == '=')
equalsTerm++;
}
numQuantums = (length + equalsTerm) / 4;
/* Don't allocate a buffer if the decoded length is 0 */
if(numQuantums == 0)
return CURLE_OK;
rawlen = (numQuantums * 3) - equalsTerm;
/* The buffer must be large enough to make room for the last quantum
(which may be partially thrown out) and the zero terminator. */
newstr = malloc(rawlen+4);
if(!newstr)
return CURLE_OUT_OF_MEMORY;
*outptr = newstr;
/* Decode all but the last quantum (which may not decode to a
multiple of 3 bytes) */
for(i = 0; i < numQuantums - 1; i++) {
decodeQuantum(newstr, src);
newstr += 3; src += 4;
}
/* This final decode may actually read slightly past the end of the buffer
if the input string is missing pad bytes. This will almost always be
harmless. */
decodeQuantum(lastQuantum, src);
for(i = 0; i < 3 - equalsTerm; i++)
newstr[i] = lastQuantum[i];
newstr[i] = '\0'; /* zero terminate */
*outlen = rawlen; /* return size of decoded data */
return CURLE_OK;
}
/*
* Curl_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.
*
* Input length of 0 indicates input buffer holds a NUL-terminated string.
*
* Returns CURLE_OK on success, otherwise specific error code. Function
* output shall not be considered valid unless CURLE_OK is returned.
*
* When encoded data length is 0, returns NULL in *outptr.
*
* @unittest: 1302
*/
CURLcode Curl_base64_encode(struct SessionHandle *data,
const char *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
CURLcode error;
unsigned char ibuf[3];
unsigned char obuf[4];
int i;
int inputparts;
char *output;
char *base64data;
char *convbuf = NULL;
const char *indata = inputbuff;
*outptr = NULL;
*outlen = 0;
if(0 == insize)
insize = strlen(indata);
base64data = output = malloc(insize*4/3+4);
if(NULL == output)
return CURLE_OUT_OF_MEMORY;
/*
* The base64 data needs to be created using the network encoding
* not the host encoding. And we can't change the actual input
* so we copy it to a buffer, translate it, and use that instead.
*/
error = Curl_convert_clone(data, indata, insize, &convbuf);
if(error) {
free(output);
return error;
}
if(convbuf)
indata = (char *)convbuf;
while(insize > 0) {
for(i = inputparts = 0; i < 3; i++) {
if(insize > 0) {
inputparts++;
ibuf[i] = (unsigned char) *indata;
indata++;
insize--;
}
else
ibuf[i] = 0;
}
obuf[0] = (unsigned char) ((ibuf[0] & 0xFC) >> 2);
obuf[1] = (unsigned char) (((ibuf[0] & 0x03) << 4) | \
((ibuf[1] & 0xF0) >> 4));
obuf[2] = (unsigned char) (((ibuf[1] & 0x0F) << 2) | \
((ibuf[2] & 0xC0) >> 6));
obuf[3] = (unsigned char) (ibuf[2] & 0x3F);
switch(inputparts) {
case 1: /* only one byte read */
snprintf(output, 5, "%c%c==",
table64[obuf[0]],
table64[obuf[1]]);
break;
case 2: /* two bytes read */
snprintf(output, 5, "%c%c%c=",
table64[obuf[0]],
table64[obuf[1]],
table64[obuf[2]]);
break;
default:
snprintf(output, 5, "%c%c%c%c",
table64[obuf[0]],
table64[obuf[1]],
table64[obuf[2]],
table64[obuf[3]] );
break;
}
output += 4;
}
*output = '\0';
*outptr = base64data; /* return pointer to new data, allocated memory */
if(convbuf)
free(convbuf);
*outlen = strlen(base64data); /* return the length of the new data */
return CURLE_OK;
}
/* ---- End of Base64 Encoding ---- */