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/*
* base64.c -- Base64 Mime encoding
*
* Copyright (c) GoAhead Software Inc., 1995-2000. All Rights Reserved.
*
* See the file "license.txt" for usage and redistribution license requirements
*
* $Id$
*/
/******************************** Description *********************************/
/*
* The base64 command encodes and decodes a string in mime base64 format
*/
/********************************* Includes ***********************************/
#include "wsIntrn.h"
/******************************** Local Data **********************************/
/*
* Mapping of ANSI chars to base64 Mime encoding alphabet (see below)
*/
static char_t map64[] = {
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, 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, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
};
static char_t alphabet64[] = {
'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
'w', 'x', 'y', 'z', '0', '1', '2', '3',
'4', '5', '6', '7', '8', '9', '+', '/',
};
/*********************************** Code *************************************/
/*
* Decode a buffer from "string" and into "outbuf"
*/
int websDecode64(char_t *outbuf, char_t *string, int outlen)
{
unsigned long shiftbuf;
char_t *cp, *op;
int c, i, j, shift;
op = outbuf;
*op = '\0';
cp = string;
while (*cp && *cp != '=') {
/*
* Map 4 (6bit) input bytes and store in a single long (shiftbuf)
*/
shiftbuf = 0;
shift = 18;
for (i = 0; i < 4 && *cp && *cp != '='; i++, cp++) {
c = map64[*cp & 0xff];
if (c == -1) {
error(E_L, E_LOG, T("Bad string: %s at %c index %d"), string,
c, i);
return -1;
}
shiftbuf = shiftbuf | (c << shift);
shift -= 6;
}
/*
* Interpret as 3 normal 8 bit bytes (fill in reverse order).
* Check for potential buffer overflow before filling.
*/
--i;
if ((op + i) >= &outbuf[outlen]) {
gstrcpy(outbuf, T("String too big"));
return -1;
}
for (j = 0; j < i; j++) {
*op++ = (char_t) ((shiftbuf >> (8 * (2 - j))) & 0xff);
}
*op = '\0';
}
return 0;
}
/******************************************************************************/
/*
* Encode a buffer from "string" into "outbuf"
*/
void websEncode64(char_t *outbuf, char_t *string, int outlen)
{
unsigned long shiftbuf;
char_t *cp, *op;
int x, i, j, shift;
op = outbuf;
*op = '\0';
cp = string;
while (*cp) {
/*
* Take three characters and create a 24 bit number in shiftbuf
*/
shiftbuf = 0;
for (j = 2; j >= 0 && *cp; j--, cp++) {
shiftbuf |= ((*cp & 0xff) << (j * 8));
}
/*
* Now convert shiftbuf to 4 base64 letters. The i,j magic calculates
* how many letters need to be output.
*/
shift = 18;
for (i = ++j; i < 4 && op < &outbuf[outlen] ; i++) {
x = (shiftbuf >> shift) & 0x3f;
*op++ = alphabet64[(shiftbuf >> shift) & 0x3f];
shift -= 6;
}
/*
* Pad at the end with '='
*/
while (j-- > 0) {
*op++ = '=';
}
*op = '\0';
}
}
/******************************************************************************/
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