base64.c

KphoneSI (kpsi) is a SIP (Session Initiation Protocol) user agent for Linux, with which you can in

#include <sys/types.h>
#include "string.h"
#include "stdlib.h"
#include "base64.h"

/* Encode a zero-terminated string in base64.  Returns the malloc-ed
   encoded line.
   Note that the string may not contain NUL characters.  */
char *base64_encode_line( const char *s )
{
	return base64_encode_string( s, strlen( s ) );
}

/*
 * Copyright (c) 1991 Bell Communications Research, Inc. (Bellcore)
 *
 * Permission to use, copy, modify, and distribute this material
 * for any purpose and without fee is hereby granted, provided
 * that the above copyright notice and this permission notice   
 * appear in all copies, and that the name of Bellcore not be
 * used in advertising or publicity pertaining to this
 * material without the specific, prior written permission
 * of an authorized representative of Bellcore.  BELLCORE
 * MAKES NO REPRESENTATIONS ABOUT THE ACCURACY OR SUITABILITY
 * OF THIS MATERIAL FOR ANY PURPOSE.  IT IS PROVIDED "AS IS",
 * WITHOUT ANY EXPRESS OR IMPLIED WARRANTIES. 
 */
char* base64_encode_string( const char *buf, unsigned int len )
{
	char basis_64[] =
		"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
	char * out;
	int inPos  = 0;
	int outPos = 0;
	int c1, c2, c3;
	unsigned int i;

	out = (char *)malloc( ( len * 4/3 ) + 8 );

	/* Get three characters at a time and encode them. */
	for( i = 0; i < len/3; ++i ) {
		c1 = buf[inPos++] & 0xFF;
		c2 = buf[inPos++] & 0xFF;
		c3 = buf[inPos++] & 0xFF;
		out[outPos++] = basis_64[(c1 & 0xFC) >> 2];
		out[outPos++] = basis_64[((c1 & 0x03) << 4) | ((c2 & 0xF0) >> 4)];
		out[outPos++] = basis_64[((c2 & 0x0F) << 2) | ((c3 & 0xC0) >> 6)];
		out[outPos++] = basis_64[c3 & 0x3F];
	}

	/* Encode the remaining one or two characters. */

	switch (len % 3) {
		case 0:
			break;
		case 1:
			c1 = buf[inPos] & 0xFF;
			out[outPos++] = basis_64[(c1 & 0xFC) >> 2];
			out[outPos++] = basis_64[((c1 & 0x03) << 4)];
			break;
		case 2:
			c1 = buf[inPos++] & 0xFF;
			c2 = buf[inPos] & 0xFF;
			out[outPos++] = basis_64[(c1 & 0xFC) >> 2];
			out[outPos++] = basis_64[((c1 & 0x03) << 4) | ((c2 & 0xF0) >> 4)];
			out[outPos++] = basis_64[((c2 & 0x0F) << 2)];
			break;
	}
	out[outPos] = 0;
	return out;
}