Source code of Windows XP (NT5)
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README.1ST:
MIME64 Encoder/Decoder
WHAT MIME64 IS: MIME64 is an encoding described in RFC1341 as MIME base64.
Its purpose is to encode binary files into ASCII so that they may be passed
through e-mail gates. In this regard, MIME64 is similar to UUENCODE.
Although most binaries these days are transmitted using UUENCODE, I
have seen a few using MIME64, and I have had requests from friends that
I decode MIME64 files that have fallen into their hands. As long as
some MIME64 continues to exist, a package such as this one is useful
to have.
WHAT THIS PACKAGE CONTAINS: This package contains both executable
and ANSI-C source code for a MIME64 encoder/decoder (MIME.EXE and
MIME.C respecively). It also contains this README file, and a MIME64
encoded file called MIME.64. The latter will decode to MIME.ZIP if
you issue the DOS command line:
MIME64 MIME.64 MIME.ZIP
If you unzip the zip file, you will get an essay by Mark Grand about
MIME.
HOW TO USE THIS PACKAGE: To decode a MIME64 file you may type:
MIME64 infile outfile
If you leave out the outfile specification, the output file will
overwrite the input file.
To encode a file into MIME64 format, type:
MIME64 infile outfile -e
Again, if you leave off the outfile specification, the output will
overwrite the input.
STATUS OF THIS PACKAGE: This package is freeware. As author, I
claim no copyright. If you change the source code and intend to
propogate that change to other users, please include a comment to
that effect at the top that states: The date of the change, the
nature of the change, and who made the change. As a courtesy, I also
ask that you retain the comment that acknowledges me as the original
author.
SEND QUESTIONS ABOUT THIS PACKAGE TO: [email protected]
Karl Hahn
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MIME64.C:
/* mime64 */
/* MIME base64 encoder/decoder by Karl Hahn [email protected] 3-Aug-94 */
#include <stdio.h>
#include <stdlib.h>
char alphabet[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
"0123456789+/";
void fputch( char blivit, FILE *f )
{
/* if (blivit == '\n') fputc( '\r', f );*/
fputc( blivit, f );
}
int classify_args( int narg,
char *rawargs[], char *fileargs[], char *optargs[] )
{
int index, jndex, kndex;
char *argptr;
for ( index = 0, jndex = 0, kndex = 0; index < narg; index++ )
{
argptr = rawargs[index];
if (*argptr == '-')
{
argptr++;
optargs[kndex++] = argptr;
}
else
{
fileargs[jndex++] = argptr;
}
}
return kndex;
}
int cvt_ascii( unsigned char alpha )
{
if ( (alpha >= 'A') && (alpha <= 'Z') ) return (int)(alpha - 'A');
else if ( (alpha >= 'a') && (alpha <= 'z') )
return 26 + (int)(alpha - 'a');
else if ( (alpha >= '0') && (alpha <= '9' ) )
return 52 + (int)(alpha - '0');
else if ( alpha == '+' ) return 62;
else if ( alpha == '/' ) return 63;
else if ( alpha == '=' ) return -2;
else return -1;
}
char *fileargs[64], *optargs[64];
struct STATE64 {
unsigned long int accum;
int shift;
};
int main( int nargs, char *cargs[] )
{
int n_options, n_files, index, jndex, shift, save_shift;
enum { ENCODE, DECODE } whattodo = DECODE;
int help_flag = 0, replace_flag = 0, quit = 0;
FILE *fin, *fout;
unsigned char blivit;
unsigned long accum, value;
char buf[80];
char *cptr, *altptr;
int decode_state;
n_options = classify_args( nargs, cargs, fileargs, optargs );
n_files = nargs - n_options;
if ( n_files < 2 ) help_flag = 1;
for ( index = 0; index < n_options; index++ )
{
if ( ( optargs[index][0] == 'e' ) ||
( optargs[index][0] == 'E' ) ) whattodo = ENCODE;
if ( optargs[index][0] == '?' ) help_flag = 1;
}
if ( help_flag )
{
printf( "mime64 infile [outfile] [-option] [-option] etc.\n\n"
"convert between binary and MIME BASE64 format\n\n"
" -e MIME base64 encode (default is decode)\n"
" -? display help message\n\n"
"if no outfile given, output file replaces infile\n" );
}
if ( n_files < 2 ) exit(0);
if ( whattodo == DECODE )
{
fin = fopen( fileargs[1], "r" );
}
else
{
fin = fopen( fileargs[1], "rb" );
}
if ( fin == 0 )
{
printf( "%s file not found\n", fileargs[1] );
exit(-1);
}
if ( n_files > 2 )
{
if ( whattodo == DECODE )
{
fout = fopen( fileargs[2], "wb" );
}
else
{
fout = fopen( fileargs[2], "w" );
}
if ( fout == 0 )
{
printf( "Couldn't open %s for output\n", fileargs[2] );
}
}
else
{
if ( whattodo == DECODE )
{
fout = fopen( "$$$$$$$$.$$$", "wb" );
}
else
{
fout = fopen( "$$$$$$$$.$$$", "w" );
}
replace_flag = 1;
}
if ( whattodo == DECODE )
{
shift = 0;
accum = 0;
decode_state = 0;
while ( ( !feof( fin ) ) && (quit == 0) )
{
fgets( buf, 80, fin );
if ( decode_state == 0 )
{
for ( index = 0;
(buf[index] != '\n') && (buf[index] != '\0') &&
(decode_state >= 0);
index++ )
{
if ( ( (buf[index] >= 'A') && (buf[index] <= 'Z') ) ||
( (buf[index] >= 'a') && (buf[index] <= 'z') ) ||
( (buf[index] >= '0') && (buf[index] <= '9') ) ||
(buf[index] == '+') ||
(buf[index] == '/') ||
(buf[index] == '=') )
{
decode_state = 1;
}
else
{
decode_state = -2;
}
}
if ( decode_state <= 0 )
{
decode_state = 0;
continue;
}
}
if ( feof(fin) )
{
quit = 1;
}
if ( quit != 0 )
{
buf[0] = '\0';
}
for ( index = 0; (buf[index] != '\n') && (buf[index] != '\0'); index++)
{
value = cvt_ascii( buf[index] );
if ( value < 64 )
{
accum <<= 6;
shift += 6;
accum |= value;
if ( shift >= 8 )
{
shift -= 8;
value = accum >> shift;
blivit = (unsigned char)value & 0xFFl;
fputc( blivit, fout );
}
}
else
{
quit = 1;
break;
}
}
}
}
else
{
fprintf ( fout,
"Content-Type: text/plain; charset=US-ASCII\n"
"Content-transfer-encoding: base64\n\n" );
shift = 0;
accum = 0;
index = 0;
while ( ( !feof( fin ) ) || (shift != 0) )
{
if ( ( !feof( fin ) ) && ( quit == 0 ) )
{
blivit = fgetc( fin );
if ( feof( fin ) )
{
quit = 1;
save_shift = shift;
blivit = 0;
}
}
else
{
quit = 1;
save_shift = shift;
blivit = 0;
}
if ( (quit == 0) || (shift != 0) )
{
value = (unsigned long)blivit;
accum <<= 8;
shift += 8;
accum |= value;
} /* ENDIF */
while ( shift >= 6 )
{
shift -= 6;
value = (accum >> shift) & 0x3Fl;
blivit = alphabet[value];
buf[index++] = blivit;
if ( index >= 60 )
{
buf[index] = '\0';
fprintf( fout, "%s\n", buf );
index = 0;
}
if ( quit != 0 )
{
shift = 0;
}
}
}
if ( save_shift == 2 )
{
buf[index++] = '=';
if ( index >= 60 )
{
buf[index] = '\0';
fprintf( fout, "%s\n", buf );
index = 0;
}
buf[index++] = '=';
if ( index >= 60 )
{
buf[index] = '\0';
fprintf( fout, "%s\n", buf );
index = 0;
}
}
else if ( save_shift == 4 )
{
buf[index++] = '=';
if ( index >= 60 )
{
buf[index] = '\0';
fprintf( fout, "%s\n", buf );
index = 0;
}
}
if ( index != 0 )
{
buf[index] = '\0';
fprintf( fout, "%s\n", buf );
}
}
fclose( fin );
fclose( fout );
if ( replace_flag )
{
if ( ( whattodo == DECODE ) && ( decode_state <= 0 ) )
{
remove( "$$$$$$$$.$$$" );
printf( "No MIME base64 lines found in %s\n", fileargs[1] );
}
else
{
remove( fileargs[1] );
rename( "$$$$$$$$.$$$", fileargs[1] );
}
}
else
{
if ( ( whattodo == DECODE ) && ( decode_state <= 0 ) )
{
remove( fileargs[2] );
printf( "No MIME base64 lines found in %s\n", fileargs[1] );
}
}
}
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