Stars of Shareware: Programmierung/SOURCE.mdf/programm/msdos/c/pgp23asr/pgpctb23/misc/pgppager.c

C/C++ Source or Header | 1993-03-07 | 5.0 KB | 205 lines

/* pgppager, designed to be possibly integrated with elm mail reader
 *
 * by Alessandro Bottonelli (c)1993, [e-mail]
 * version 1.0 - 29/Jan/93
 *
 * This program is put in the public domain and permission is granted
 * to use it for any purpose, provided this copyright notice is retained.
 * NO WARRANTIES expressed or implied are given. USE THIS PROGRAM AT
 * YOUR OWN RISK!
 *
 * This programs reads from a specified file or from stdin if no file is
 * specified and creates three temporary files (header, encrypted, and
 * trailer) as needed, in order to store the header portion in cleartext,
 * the encrypted portion still in cypher text, and the trailer portion of
 * the clear text. Then, if applicable, the cleartext header is outputted,
 * the encrypted portion is piped through pgp as needed, then the trailer
 * (if any) is outputted. THIS PROCESS IS TRANSPARENT TO NON PGP ENCRYPTED
 * TEXTS
 *
 * For use with ELM, it is necessary to specify the display to be:
 *
 *    <whatever_path>/pgppager | pg
 *
 * in the elm option menu.
 *
 */

#include <stdio.h>

/*
 * you may need to customize the next DEFINEs
 */

#define PGP "/usr/local/bin/pgp -f"
#define BEGIN "-----BEGIN PGP MESSAGE---"
#define END "-----END PGP MESSAGE---"


#define TEMP "/usr/tmp"        /* Temporary dir of your choice       */
#define CAT "cat -s"        /* -s option to avoid cat complaining */
                /* about missing files                */

/*
 * program should be invoked as "pgppager [file] | pg"
 * actually no check is made to verify that the program
 * is piped through "pg" or "more", just in case someone
 * wants to redirect it to a file or a printer.
 * BEWARE: redirecting it to a file or printer may be
 * not good for your security if the file or printer level
 * of security is unknown or poor ...
 */

/*
 * This three variables global to be visible to the Exit() routine
 */

char fh[128];    /* Header temporary file        */
char fe[128];    /* Encrypted temporary file     */
char fr[128];    /* Trailer temporary file       */

main(ac,av)
int ac;
char **av;
{
    FILE *fp;    /* File pointer to read file(s) */
    FILE *ft;    /* File pointer to temp file(s) */
    char line[256]; /* Read/Write buffer            */
    char cmd[128];    /* command string               */



/*
 * Must be invoked as "pgppager [file_name]"
 */

    if ( ac > 2 )
    {
        fprintf(stderr,"Usage: %s [file_name]\n", av[0]);
        Exit(1);
    }

/*
 * File ( if specified ) must exist and be readable
 */

    if ( ac == 2 )
    {
        if ( ( fp = fopen( av[1], "r") ) == NULL )
        {
            fprintf(stderr,"%s: cannot read %s\n", av[0], av[1]);
            Exit(2);
        }
    }
    else
        fp=stdin;    /* if no file specified assume standard input */

/*
 * Build temporary file names
 *
 * please note how, as files are created for writing, they are
 * also chmod(ed) to 0600. I expect most PGP users to have their
 * umask set to 077, but just to be on the safe side ... :-)
 */

    sprintf ( fh, "%s/pgpm.head.%d", TEMP, (int )getpid() );
    sprintf ( fe, "%s/pgpm.encr.%d", TEMP, (int )getpid() );
    sprintf ( fr, "%s/pgpm.trai.%d", TEMP, (int )getpid() );


/*
 * READ file until Eof, redirect to "fe"  only those portions of the
 * file that are between the BEGIN PGP and END PGP MESSAGE lines.
 */
    if ( ( ft = fopen ( fh, "w") ) == NULL )
    {
        fprintf(stderr,"%s: error opening temp file\n", av[0]);
        Exit(4);
    }

    if ( (int )chmod( fh, 0600) != 0 )
    {
        fprintf(stderr,"%s: cannot chmod temp file\n", av[0]);
        Exit(5);
    }

    fprintf( ft, "\n");    /* Just to start with a blank line */

    while ( fgets( line, 128, fp) != NULL )
    {
        if ( !strncmp( BEGIN, line, strlen( BEGIN) ))
        {
            fprintf(ft, "\n===pgp encrypted message begins===\n");
            fclose(ft);

            if ( ( ft = fopen ( fe, "w") ) == NULL )
            {
                fprintf(stderr,"%s: error opening temp file\n", av[0]);
                Exit(4);
            }

            if ( (int )chmod( fe, 0600) != 0 )
            {
                fprintf(stderr,"%s: cannot chmod temp file\n", av[0]);
                Exit(5);
            }
        }

        fprintf( ft, "%s", line);

        if ( !strncmp( END, line, strlen( END) ))
        {
            fclose(ft);

            if ( ( ft = fopen ( fr, "w") ) == NULL )
            {
                fprintf(stderr,"%s: error opening temp file\n", av[0]);
                Exit(4);
            }

            if ( (int )chmod( fr, 0600) != 0 )
            {
                fprintf(stderr,"%s: cannot chmod temp file\n", av[0]);
                Exit(5);
            }

            fprintf(ft, "\n===pgp encrypted message ends===\n");
        }
    }

    fclose(fp);
    fclose(ft);

    sprintf( cmd, "%s %s", CAT, fh);
    system(cmd);
    sprintf( cmd, "%s %s | %s", CAT, fe, PGP);
    system(cmd);
    sprintf( cmd, "%s %s", CAT, fr);
    system(cmd);

    Exit(0);    /* That's all folks ... */
}

/*
 * Exit(s) are centralized in this routine to make sure we wipe out
 * temporary files in any case ...
 */

Exit(n)
int n;        /* value to be returned to the shell (0 = OK) */
{
/*
 * Remove temporary files (if any)
 * and sync() just for the sake of it
 */

    unlink(fh);
    unlink(fe);
    unlink(fr);
    sync();

    exit(n);
}