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curl/lib/base64.c
Daniel Stenberg dcd6f81025
snprintf: renamed and we now only use msnprintf()
The function does not return the same value as snprintf() normally does,
so readers may be mislead into thinking the code works differently than
it actually does. A different function name makes this easier to detect.

Reported-by: Tomas Hoger
Assisted-by: Daniel Gustafsson
Fixes #3296
Closes #3297
2018-11-23 08:26:51 +01:00

320 lines
8.3 KiB
C

/***************************************************************************
* _ _ ____ _
* Project ___| | | | _ \| |
* / __| | | | |_) | |
* | (__| |_| | _ <| |___
* \___|\___/|_| \_\_____|
*
* Copyright (C) 1998 - 2018, 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.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 "curl_setup.h"
#include "urldata.h" /* for the Curl_easy definition */
#include "warnless.h"
#include "curl_base64.h"
#include "non-ascii.h"
/* The last 3 #include files should be in this order */
#include "curl_printf.h"
#include "curl_memory.h"
#include "memdebug.h"
/* ---- Base64 Encoding/Decoding Table --- */
static const char base64[]=
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
/* The Base 64 encoding with an URL and filename safe alphabet, RFC 4648
section 5 */
static const char base64url[]=
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_";
static size_t decodeQuantum(unsigned char *dest, const char *src)
{
size_t padding = 0;
const char *s, *p;
unsigned long i, x = 0;
for(i = 0, s = src; i < 4; i++, s++) {
if(*s == '=') {
x = (x << 6);
padding++;
}
else {
unsigned long v = 0;
p = base64;
while(*p && (*p != *s)) {
v++;
p++;
}
if(*p == *s)
x = (x << 6) + v;
else
return 0;
}
}
if(padding < 1)
dest[2] = curlx_ultouc(x & 0xFFUL);
x >>= 8;
if(padding < 2)
dest[1] = curlx_ultouc(x & 0xFFUL);
x >>= 8;
dest[0] = curlx_ultouc(x & 0xFFUL);
return 3 - padding;
}
/*
* 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 srclen = 0;
size_t length = 0;
size_t padding = 0;
size_t i;
size_t numQuantums;
size_t rawlen = 0;
unsigned char *pos;
unsigned char *newstr;
*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;
/* Find the position of any = padding characters */
while((src[length] != '=') && src[length])
length++;
/* A maximum of two = padding characters is allowed */
if(src[length] == '=') {
padding++;
if(src[length + 1] == '=')
padding++;
}
/* Check the = padding characters weren't part way through the input */
if(length + padding != srclen)
return CURLE_BAD_CONTENT_ENCODING;
/* Calculate the number of quantums */
numQuantums = srclen / 4;
/* Calculate the size of the decoded string */
rawlen = (numQuantums * 3) - padding;
/* Allocate our buffer including room for a zero terminator */
newstr = malloc(rawlen + 1);
if(!newstr)
return CURLE_OUT_OF_MEMORY;
pos = newstr;
/* Decode the quantums */
for(i = 0; i < numQuantums; i++) {
size_t result = decodeQuantum(pos, src);
if(!result) {
free(newstr);
return CURLE_BAD_CONTENT_ENCODING;
}
pos += result;
src += 4;
}
/* Zero terminate */
*pos = '\0';
/* Return the decoded data */
*outptr = newstr;
*outlen = rawlen;
return CURLE_OK;
}
static CURLcode base64_encode(const char *table64,
struct Curl_easy *data,
const char *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
CURLcode result;
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(!insize)
insize = strlen(indata);
#if SIZEOF_SIZE_T == 4
if(insize > UINT_MAX/4)
return CURLE_OUT_OF_MEMORY;
#endif
base64data = output = malloc(insize * 4 / 3 + 4);
if(!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.
*/
result = Curl_convert_clone(data, indata, insize, &convbuf);
if(result) {
free(output);
return result;
}
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 */
msnprintf(output, 5, "%c%c==",
table64[obuf[0]],
table64[obuf[1]]);
break;
case 2: /* two bytes read */
msnprintf(output, 5, "%c%c%c=",
table64[obuf[0]],
table64[obuf[1]],
table64[obuf[2]]);
break;
default:
msnprintf(output, 5, "%c%c%c%c",
table64[obuf[0]],
table64[obuf[1]],
table64[obuf[2]],
table64[obuf[3]]);
break;
}
output += 4;
}
/* Zero terminate */
*output = '\0';
/* Return the pointer to the new data (allocated memory) */
*outptr = base64data;
free(convbuf);
/* Return the length of the new data */
*outlen = strlen(base64data);
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 Curl_easy *data,
const char *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
return base64_encode(base64, data, inputbuff, insize, outptr, outlen);
}
/*
* Curl_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 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_base64url_encode(struct Curl_easy *data,
const char *inputbuff, size_t insize,
char **outptr, size_t *outlen)
{
return base64_encode(base64url, data, inputbuff, insize, outptr, outlen);
}