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/*
* File: base64.c
* Description: Simple BASE64 conversion methods
* Author: Ari Edelkind
* License: Public Domain
* Website: http://episec.com/people/edelkind/c.html
*/
#include <string.h>
char b64string[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
long base64_encode (to, from, len)
char *to, *from;
unsigned int len;
{
char *fromp = from;
char *top = to;
unsigned char cbyte;
unsigned char obyte;
char end[3];
for (; len >= 3; len -= 3) {
cbyte = *fromp++;
*top++ = b64string[(int)(cbyte >> 2)];
obyte = (cbyte << 4) & 0x30; /* 0011 0000 */
cbyte = *fromp++;
obyte |= (cbyte >> 4); /* 0000 1111 */
*top++ = b64string[(int)obyte];
obyte = (cbyte << 2) & 0x3C; /* 0011 1100 */
cbyte = *fromp++;
obyte |= (cbyte >> 6); /* 0000 0011 */
*top++ = b64string[(int)obyte];
*top++ = b64string[(int)(cbyte & 0x3F)];/* 0011 1111 */
}
if (len) {
end[0] = *fromp++;
if (--len) end[1] = *fromp++; else end[1] = 0;
end[2] = 0;
cbyte = end[0];
*top++ = b64string[(int)(cbyte >> 2)];
obyte = (cbyte << 4) & 0x30; /* 0011 0000 */
cbyte = end[1];
obyte |= (cbyte >> 4);
*top++ = b64string[(int)obyte];
obyte = (cbyte << 2) & 0x3C; /* 0011 1100 */
if (len) *top++ = b64string[(int)obyte];
else *top++ = '=';
*top++ = '=';
}
*top = 0;
return top - to;
}
/* badchar(): check if c is decent; puts either the */
/* location of c or null into p. */
#define badchar(c,p) (!(p = memchr(b64string, c, 64)))
long base64_decode (to, from, len)
char *to, *from;
unsigned int len;
{
char *fromp = from;
char *top = to;
char *p;
unsigned char cbyte;
unsigned char obyte;
int padding = 0;
for (; len >= 4; len -= 4) {
if ((cbyte = *fromp++) == '=') cbyte = 0;
else {
if (badchar(cbyte, p)) return -1;
cbyte = (p - b64string);
}
obyte = cbyte << 2; /* 1111 1100 */
if ((cbyte = *fromp++) == '=') cbyte = 0;
else {
if (badchar(cbyte, p)) return -1;
cbyte = p - b64string;
}
obyte |= cbyte >> 4; /* 0000 0011 */
*top++ = obyte;
obyte = cbyte << 4; /* 1111 0000 */
if ((cbyte = *fromp++) == '=') { cbyte = 0; padding++; }
else {
padding = 0;
if (badchar (cbyte, p)) return -1;
cbyte = p - b64string;
}
obyte |= cbyte >> 2; /* 0000 1111 */
*top++ = obyte;
obyte = cbyte << 6; /* 1100 0000 */
if ((cbyte = *fromp++) == '=') { cbyte = 0; padding++; }
else {
padding = 0;
if (badchar (cbyte, p)) return -1;
cbyte = p - b64string;
}
obyte |= cbyte; /* 0011 1111 */
*top++ = obyte;
}
*top = 0;
if (len) return -1;
return (top - to) - padding;
}
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