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/*++
/* NAME
/* base64_code 3
/* SUMMARY
/* encode/decode data, base 64 style
/* SYNOPSIS
/* #include <base64_code.h>
/*
/* VSTRING *base64_encode(result, in, len)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/*
/* VSTRING *base64_decode(result, in, len)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/*
/* VSTRING *base64_encode_opt(result, in, len, flags)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/* int flags;
/*
/* VSTRING *base64_decode_opt(result, in, len, flags)
/* VSTRING *result;
/* const char *in;
/* ssize_t len;
/* int flags;
/* DESCRIPTION
/* base64_encode() takes a block of len bytes and encodes it as one
/* null-terminated string. The result value is the result argument.
/*
/* base64_decode() performs the opposite transformation. The result
/* value is the result argument. The result is null terminated, whether
/* or not that makes sense.
/*
/* base64_encode_opt() and base64_decode_opt() provide extended
/* interfaces. In both cases the flags arguments is the bit-wise
/* OR of zero or more the following:
/* .IP BASE64_FLAG_APPEND
/* Append the result, instead of overwriting the result buffer.
/* .PP
/* For convenience, BASE64_FLAG_NONE specifies none of the above.
/* DIAGNOSTICS
/* base64_decode () returns a null pointer when the input contains
/* characters not in the base 64 alphabet.
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
/* System library. */
#include "sys_defs.h"
#include <ctype.h>
#include <string.h>
#include <limits.h>
#ifndef UCHAR_MAX
#define UCHAR_MAX 0xff
#endif
/* Utility library. */
#include <msg.h>
#include <mymalloc.h>
#include <vstring.h>
#include <base64_code.h>
/* Application-specific. */
static unsigned char to_b64[] =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
#define UNSIG_CHAR_PTR(x) ((unsigned char *)(x))
/* base64_encode - raw data to encoded */
#undef base64_encode
extern VSTRING *base64_encode(VSTRING *, const char *, ssize_t);
VSTRING *base64_encode(VSTRING *result, const char *in, ssize_t len)
{
return (base64_encode_opt(result, in, len, BASE64_FLAG_NONE));
}
VSTRING *base64_encode_opt(VSTRING *result, const char *in, ssize_t len,
int flags)
{
const unsigned char *cp;
ssize_t count;
/*
* Encode 3 -> 4.
*/
if ((flags & BASE64_FLAG_APPEND) == 0)
VSTRING_RESET(result);
for (cp = UNSIG_CHAR_PTR(in), count = len; count > 0; count -= 3, cp += 3) {
VSTRING_ADDCH(result, to_b64[cp[0] >> 2]);
if (count > 1) {
VSTRING_ADDCH(result, to_b64[(cp[0] & 0x3) << 4 | cp[1] >> 4]);
if (count > 2) {
VSTRING_ADDCH(result, to_b64[(cp[1] & 0xf) << 2 | cp[2] >> 6]);
VSTRING_ADDCH(result, to_b64[cp[2] & 0x3f]);
} else {
VSTRING_ADDCH(result, to_b64[(cp[1] & 0xf) << 2]);
VSTRING_ADDCH(result, '=');
break;
}
} else {
VSTRING_ADDCH(result, to_b64[(cp[0] & 0x3) << 4]);
VSTRING_ADDCH(result, '=');
VSTRING_ADDCH(result, '=');
break;
}
}
VSTRING_TERMINATE(result);
return (result);
}
/* base64_decode - encoded data to raw */
#undef base64_decode
extern VSTRING *base64_decode(VSTRING *, const char *, ssize_t);
VSTRING *base64_decode(VSTRING *result, const char *in, ssize_t len)
{
return (base64_decode_opt(result, in, len, BASE64_FLAG_NONE));
}
VSTRING *base64_decode_opt(VSTRING *result, const char *in, ssize_t len,
int flags)
{
static unsigned char *un_b64 = 0;
const unsigned char *cp;
ssize_t count;
unsigned int ch0;
unsigned int ch1;
unsigned int ch2;
unsigned int ch3;
#define CHARS_PER_BYTE (UCHAR_MAX + 1)
#define INVALID 0xff
/*
* Sanity check.
*/
if (len % 4)
return (0);
/*
* Once: initialize the decoding lookup table on the fly.
*/
if (un_b64 == 0) {
un_b64 = (unsigned char *) mymalloc(CHARS_PER_BYTE);
memset(un_b64, INVALID, CHARS_PER_BYTE);
for (cp = to_b64; cp < to_b64 + sizeof(to_b64) - 1; cp++)
un_b64[*cp] = cp - to_b64;
}
/*
* Decode 4 -> 3.
*/
if ((flags & BASE64_FLAG_APPEND) == 0)
VSTRING_RESET(result);
for (cp = UNSIG_CHAR_PTR(in), count = 0; count < len; count += 4) {
if ((ch0 = un_b64[*cp++]) == INVALID
|| (ch1 = un_b64[*cp++]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch0 << 2 | ch1 >> 4);
if ((ch2 = *cp++) == '=')
break;
if ((ch2 = un_b64[ch2]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch1 << 4 | ch2 >> 2);
if ((ch3 = *cp++) == '=')
break;
if ((ch3 = un_b64[ch3]) == INVALID)
return (0);
VSTRING_ADDCH(result, ch2 << 6 | ch3);
}
VSTRING_TERMINATE(result);
return (result);
}
#ifdef TEST
/*
* Proof-of-concept test program: convert to base 64 and back.
*/
#define STR(x) vstring_str(x)
#define LEN(x) VSTRING_LEN(x)
int main(int unused_argc, char **unused_argv)
{
VSTRING *b1 = vstring_alloc(1);
VSTRING *b2 = vstring_alloc(1);
char test[256];
int n;
for (n = 0; n < sizeof(test); n++)
test[n] = n;
base64_encode(b1, test, sizeof(test));
if (base64_decode(b2, STR(b1), LEN(b1)) == 0)
msg_panic("bad base64: %s", STR(b1));
if (LEN(b2) != sizeof(test))
msg_panic("bad decode length: %ld != %ld",
(long) LEN(b2), (long) sizeof(test));
for (n = 0; n < sizeof(test); n++)
if (STR(b2)[n] != test[n])
msg_panic("bad decode value %d != %d",
(unsigned char) STR(b2)[n], (unsigned char) test[n]);
vstring_free(b1);
vstring_free(b2);
return (0);
}
#endif
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