Grackle68k

/*********************************************************************\

MODULE NAME:    b64.c

AUTHOR:         Bob Trower 08/04/01

PROJECT:        Crypt Data Packaging

COPYRIGHT:      Copyright (c) Trantor Standard Systems Inc., 2001

NOTE:           This source code may be used as you wish, subject to

                the MIT license.  See the LICENCE section below.

DESCRIPTION:

                This little utility implements the Base64

                Content-Transfer-Encoding standard described in

                RFC1113 (http://www.faqs.org/rfcs/rfc1113.html).

                This is the coding scheme used by MIME to allow

                binary data to be transferred by SMTP mail.

                Groups of 3 bytes from a binary stream are coded as

                groups of 4 bytes in a text stream.

                The input stream is 'padded' with zeros to create

                an input that is an even multiple of 3.

                A special character ('=') is used to denote padding so

                that the stream can be decoded back to its exact size.

                Encoded output is formatted in lines which should

                be a maximum of 72 characters to conform to the

                specification.  This program defaults to 72 characters,

                but will allow more or less through the use of a

                switch.  The program enforces a minimum line size

                of 4 characters.

                Example encoding:

                The stream 'ABCD' is 32 bits long.  It is mapped as

                follows:

                ABCD

                 A (65)     B (66)     C (67)     D (68)   (None) (None)

                01000001   01000010   01000011   01000100

                16 (Q)  20 (U)  9 (J)   3 (D)    17 (R) 0 (A)  NA (=) NA (=)

                010000  010100  001001  000011   010001 000000 000000 000000

                QUJDRA==

                Decoding is the process in reverse.  A 'decode' lookup

                table has been created to avoid string scans.

DESIGN GOALS:        Specifically:

                Code is a stand-alone utility to perform base64 

                encoding/decoding. It should be genuinely useful 

                when the need arises and it meets a need that is 

                likely to occur for some users.  

                Code acts as sample code to show the author's 

                design and coding style.  

                Generally: 

                This program is designed to survive:

                Everything you need is in a single source file.

                It compiles cleanly using a vanilla ANSI C compiler.

                It does its job correctly with a minimum of fuss.  

                The code is not overly clever, not overly simplistic 

                and not overly verbose. 

                Access is 'cut and paste' from a web page.  

                Terms of use are reasonable.  

VALIDATION:     Non-trivial code is never without errors.  This

                file likely has some problems, since it has only

                been tested by the author.  It is expected with most

                source code that there is a period of 'burn-in' when

                problems are identified and corrected.  That being

                said, it is possible to have 'reasonably correct'

                code by following a regime of unit test that covers

                the most likely cases and regression testing prior

                to release.  This has been done with this code and

                it has a good probability of performing as expected.

                Unit Test Cases:

                case 0:empty file:

                    CASE0.DAT  ->  ->

                    (Zero length target file created

                    on both encode and decode.)

                case 1:One input character:

                    CASE1.DAT A -> QQ== -> A

                case 2:Two input characters:

                    CASE2.DAT AB -> QUJD -> AB

                case 3:Three input characters:

                    CASE3.DAT ABC -> QUJD -> ABC

                case 4:Four input characters:

                    case4.dat ABCD -> QUJDRA== -> ABCD

                case 5:All chars from 0 to ff, linesize set to 50:

                    AAECAwQFBgcICQoLDA0ODxAREhMUFRYXGBkaGxwdHh8gISIj

                    JCUmJygpKissLS4vMDEyMzQ1Njc4OTo7PD0+P0BBQkNERUZH

                    SElKS0xNTk9QUVJTVFVWV1hZWltcXV5fYGFiY2RlZmdoaWpr

                    bG1ub3BxcnN0dXZ3eHl6e3x9fn+AgYKDhIWGh4iJiouMjY6P

                    kJGSk5SVlpeYmZqbnJ2en6ChoqOkpaanqKmqq6ytrq+wsbKz

                    tLW2t7i5uru8vb6/wMHCw8TFxsfIycrLzM3Oz9DR0tPU1dbX

                    2Nna29zd3t/g4eLj5OXm5+jp6uvs7e7v8PHy8/T19vf4+fr7

                    /P3+/w==

                case 6:Mime Block from e-mail:

                    (Data same as test case 5)

                case 7: Large files:

                    Tested 28 MB file in/out.

                case 8: Random Binary Integrity:

                    This binary program (b64.exe) was encoded to base64,

                    back to binary and then executed.

                case 9 Stress:

                    All files in a working directory encoded/decoded

                    and compared with file comparison utility to

                    ensure that multiple runs do not cause problems

                    such as exhausting file handles, tmp storage, etc.

                -------------

                Syntax, operation and failure:

                    All options/switches tested.  Performs as

                    expected.

                case 10:

                    No Args -- Shows Usage Screen

                    Return Code 1 (Invalid Syntax)

                case 11:

                    One Arg (invalid) -- Shows Usage Screen

                    Return Code 1 (Invalid Syntax)

                case 12:

                    One Arg Help (-?) -- Shows detailed Usage Screen.

                    Return Code 0 (Success -- help request is valid).

                case 13:

                    One Arg Help (-h) -- Shows detailed Usage Screen.

                    Return Code 0 (Success -- help request is valid).

                case 14:

                    One Arg (valid) -- Uses stdin/stdout (filter)

                    Return Code 0 (Sucess)

                case 15:

                    Two Args (invalid file) -- shows system error.

                    Return Code 2 (File Error)

                case 16:

                    Encode non-existent file -- shows system error.

                    Return Code 2 (File Error)

                case 17:

                    Out of disk space -- shows system error.

                    Return Code 3 (File I/O Error)

                -------------

                Compile/Regression test:

                    gcc compiled binary under Cygwin

                    Microsoft Visual Studio under Windows 2000

                    Microsoft Version 6.0 C under Windows 2000

DEPENDENCIES:   None

LICENCE:        Copyright (c) 2001 Bob Trower, Trantor Standard Systems Inc.

                Permission is hereby granted, free of charge, to any person

                obtaining a copy of this software and associated

                documentation files (the "Software"), to deal in the

                Software without restriction, including without limitation

                the rights to use, copy, modify, merge, publish, distribute,

                sublicense, and/or sell copies of the Software, and to

                permit persons to whom the Software is furnished to do so,

                subject to the following conditions:

                The above copyright notice and this permission notice shall

                be included in all copies or substantial portions of the

                Software.

                THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY

                KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE

                WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR

                PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS

                OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR

                OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR

                OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE

                SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

VERSION HISTORY:

                Bob Trower 08/04/01 -- Create Version 0.00.00B

\******************************************************************* */

#include <stdio.h>

#include <stdlib.h>

/*

** Translation Table as described in RFC1113

*/

static const char cb64[]="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

/*

** Translation Table to decode (created by author)

*/

static const char cd64[]="|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$XYZ[\\]^_`abcdefghijklmnopq";

/*

** encodeblock

**

** encode 3 8-bit binary bytes as 4 '6-bit' characters

*/

void encodeblock( unsigned char in[3], unsigned char out[4], int len )

{

    out[0] = cb64[ in[0] >> 2 ];

    out[1] = cb64[ ((in[0] & 0x03) << 4) | ((in[1] & 0xf0) >> 4) ];

    out[2] = (unsigned char) (len > 1 ? cb64[ ((in[1] & 0x0f) << 2) | ((in[2] & 0xc0) >> 6) ] : '=');

    out[3] = (unsigned char) (len > 2 ? cb64[ in[2] & 0x3f ] : '=');

}

/*

** encode

**

** base64 encode a stream adding padding and line breaks as per spec.

*/

void encode( FILE *infile, FILE *outfile, int linesize )

{

    unsigned char in[3], out[4];

    int i, len, blocksout = 0;

    while( !feof( infile ) ) {

        len = 0;

        for( i = 0; i < 3; i++ ) {

            in[i] = (unsigned char) getc( infile );

            if( !feof( infile ) ) {

                len++;

            }

            else {

                in[i] = 0;

            }

        }

        if( len ) {

            encodeblock( in, out, len );

            for( i = 0; i < 4; i++ ) {

                putc( out[i], outfile );

            }

            blocksout++;

        }

        if( blocksout >= (linesize/4) || feof( infile ) ) {

            if( blocksout ) {

                fprintf( outfile, "\r\n" );

            }

            blocksout = 0;

        }

    }

}

/*

** decodeblock

**

** decode 4 '6-bit' characters into 3 8-bit binary bytes

*/

void decodeblock( unsigned char in[4], unsigned char out[3] )

{   

    out[ 0 ] = (unsigned char ) (in[0] << 2 | in[1] >> 4);

    out[ 1 ] = (unsigned char ) (in[1] << 4 | in[2] >> 2);

    out[ 2 ] = (unsigned char ) (((in[2] << 6) & 0xc0) | in[3]);

}

/*

** decode

**

** decode a base64 encoded stream discarding padding, line breaks and noise

*/

void decode( FILE *infile, FILE *outfile )

{

    unsigned char in[4], out[3], v;

    int i, len;

    while( !feof( infile ) ) {

        for( len = 0, i = 0; i < 4 && !feof( infile ); i++ ) {

            v = 0;

            while( !feof( infile ) && v == 0 ) {

                v = (unsigned char) getc( infile );

                v = (unsigned char) ((v < 43 || v > 122) ? 0 : cd64[ v - 43 ]);

                if( v ) {

                    v = (unsigned char) ((v == '$') ? 0 : v - 61);

                }

            }

            if( !feof( infile ) ) {

                len++;

                if( v ) {

                    in[ i ] = (unsigned char) (v - 1);

                }

            }

            else {

                in[i] = 0;

            }

        }

        if( len ) {

            decodeblock( in, out );

            for( i = 0; i < len - 1; i++ ) {

                putc( out[i], outfile );

            }

        }

    }

}

/*

** returnable errors

**

** Error codes returned to the operating system.

**

*/

#define B64_SYNTAX_ERROR        1

#define B64_FILE_ERROR          2

#define B64_FILE_IO_ERROR       3

#define B64_ERROR_OUT_CLOSE     4

#define B64_LINE_SIZE_TO_MIN    5

/*

** b64_message

**

** Gather text messages in one place.

**

*/

char *b64_message( int errcode )

{

    #define B64_MAX_MESSAGES 6

    char *msgs[ B64_MAX_MESSAGES ] = {

            "b64:000:Invalid Message Code.",

            "b64:001:Syntax Error -- check help for usage.",

            "b64:002:File Error Opening/Creating Files.",

            "b64:003:File I/O Error -- Note: output file not removed.",

            "b64:004:Error on output file close.",

            "b64:004:linesize set to minimum."

    };

    char *msg = msgs[ 0 ];

    if( errcode > 0 && errcode < B64_MAX_MESSAGES ) {

        msg = msgs[ errcode ];

    }

    return( msg );

}

/*

** b64

**

** 'engine' that opens streams and calls encode/decode

*/

int b64( int opt, char *infilename, char *outfilename, int linesize )

{

    FILE *infile;

    int retcode = B64_FILE_ERROR;

    if( !infilename ) {

        infile = stdin;

    }

    else {

        infile = fopen( infilename, "rb" );

    }

    if( !infile ) {

        perror( infilename );

    }

    else {

        FILE *outfile;

        if( !outfilename ) {

            outfile = stdout;

        }

        else {

            outfile = fopen( outfilename, "wb" );

        }

        if( !outfile ) {

            perror( outfilename );

        }

        else {

            if( opt == 'e' ) {

                encode( infile, outfile, linesize );

            }

            else {

                decode( infile, outfile );

            }

            if (ferror( infile ) || ferror( outfile )) {

                retcode = B64_FILE_IO_ERROR;

            }

            else {

                 retcode = 0;

            }

            if( outfile != stdout ) {

                if( fclose( outfile ) != 0 ) {

                    perror( b64_message( B64_ERROR_OUT_CLOSE ) );

                    retcode = B64_FILE_IO_ERROR;

                }

            }

        }

        if( infile != stdin ) {

            fclose( infile );

        }

    }

    return( retcode );

}

/*

** showuse

**

** display usage information, help, version info

*/

void showuse( int morehelp )

{

    {

        printf( "\n" );

        printf( "  b64      (Base64 Encode/Decode)      Bob Trower 08/03/01 \n" );

        printf( "           (C) Copr Bob Trower 1986-01.      Version 0.00B \n" );

        printf( "  Usage:   b64 -option  [ -l num ] [<FileIn> [<FileOut>]]  \n" );

        printf( "  Purpose: This program is a simple utility that implements\n" );

        printf( "           Base64 Content-Transfer-Encoding (RFC1113).     \n" );

    }

    if( !morehelp ) {

        printf( "           Use -h option for additional help.              \n" );

    }

    else {

        printf( "  Options: -e  encode to Base64   -h  This help text.      \n" );

        printf( "           -d  decode from Base64 -?  This help text.      \n" );

        printf( "  Note:    -l  use to change line size (from 72 characters)\n" );

        printf( "  Returns: 0 = success.  Non-zero is an error code.        \n" );

        printf( "  ErrCode: 1 = Bad Syntax, 2 = File Open, 3 = File I/O     \n" );

        printf( "  Example: b64 -e binfile b64file     <- Encode to b64     \n" );

        printf( "           b64 -d b64file binfile     <- Decode from b64   \n" );

        printf( "           b64 -e -l40 infile outfile <- Line Length of 40 \n" );

        printf( "  Note:    Will act as a filter, but this should only be   \n" );

        printf( "           used on text files due to translations made by  \n" );

        printf( "           operating systems.                              \n" );

        printf( "  Release: 0.00.00, Tue Aug 7   2:00:00 2001, ANSI-SOURCE C\n" );

    }

}

#define B64_DEF_LINE_SIZE   72

#define B64_MIN_LINE_SIZE    4

#define THIS_OPT(ac, av) (ac > 1 ? av[1][0] == '-' ? av[1][1] : 0 : 0)

/*

** main

**

** parse and validate arguments and call b64 engine or help

*/

int main( int argc, char **argv )

{

    int opt = 0;

    int retcode = 0;

    int linesize = B64_DEF_LINE_SIZE;

    char *infilename = NULL, *outfilename = NULL;

    while( THIS_OPT( argc, argv ) ) {

        switch( THIS_OPT(argc, argv) ) {

            case 'l':

                    linesize = atoi( &(argv[1][2]) );

                    if( linesize < B64_MIN_LINE_SIZE ) {

                        linesize = B64_MIN_LINE_SIZE;

                        printf( "%s\n", b64_message( B64_LINE_SIZE_TO_MIN ) );

                    }

                    break;

            case '?':

            case 'h':

                    opt = 'h';

                    break;

            case 'e':

            case 'd':

                    opt = THIS_OPT(argc, argv);

                    break;

             default:

                    opt = 0;

                    break;

        }

        argv++;

        argc--;

    }

    switch( opt ) {

        case 'e':

        case 'd':

            infilename = argc > 1 ? argv[1] : NULL;

            outfilename = argc > 2 ? argv[2] : NULL;

            retcode = b64( opt, infilename, outfilename, linesize );

            break;

        case 0:

            retcode = B64_SYNTAX_ERROR;

        case 'h':

            showuse( opt );

            break;

    }

    if( retcode ) {

        printf( "%s\n", b64_message( retcode ) );

    }

    return( retcode );

}