/*
 *  selinux_test.c - Program pro overeni funkcnosti zabezpeceni SELinuxem
 *
 *  This is an example file for the UNIX - Seminar of System Administration
 *  course.
 *
 *  Copyright (C) 2008  Jan "Yenya" Kasprzak <kas@fi.muni.cz>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 */

/*
 * Zkompilovat pomoci
 *            cc -Wall -o selinux_test selinux_test.c
 * pripadne
 *            cc -Wall -DPROBE_SECURITY -o selinux_test selinux_test.c
 */
#include <unistd.h>
#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>
#include <errno.h>

#ifdef PROBE_SECURITY
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#endif


static void die(char *msg, ...)
{
	va_list ap;

	va_start(ap, msg);
	vfprintf(stderr, msg, ap);
	va_end(ap);
	exit(1);
}

int main(int argc, char **argv)
{
	FILE *infile, *outfile;
	char *infilename, *outfilename;
	int c, bytes = 0, modified = 0;

#ifdef PROBE_SECURITY
	int sock;
	struct sockaddr_in sin;
	struct in_addr ina;
#endif

	fprintf(stderr, "Starting up.\n");

#ifdef PROBE_SECURITY
	fprintf(stderr, "PROBE_SECURITY compiled in.\n");
	fprintf(stderr, "Trying to open /etc/passwd: ");
	if ((infile = fopen("/etc/passwd", "r")))
		fprintf(stderr, "BAD: I can read /etc/passwd!\n");
	else
		fprintf(stderr, "OK: Can't read /etc/passwd.\n");

	fprintf(stderr, "Trying to get AF_INET socket: ");
	if ((sock = socket(AF_INET, SOCK_STREAM, 0)) == -1) {
		fprintf(stderr, "OK: Can't create socket.\n");
		goto SOCK_FAIL;
	} else
		fprintf(stderr, "maybe BAD: I can get a socket.\n");

	inet_aton("127.0.0.1", &ina);
	sin.sin_family = AF_INET;
	sin.sin_addr = ina;
	sin.sin_port = htons(22); /* SSH */

	fprintf(stderr, "Trying to connect to 127.0.0.1:22: ");
	if (connect(sock, (struct sockaddr *)&sin, sizeof(sin)))
		fprintf(stderr, "OK: Can't connect.\n");
	else
		fprintf(stderr, "BAD: I can connect to 127.0.0.1:22!\n");

SOCK_FAIL:
	fprintf(stderr, "Trying to exec /bin/sh. "
		"If you will see the shell prompt now, it is BAD!\n");
	putenv("PS1=BAD: got a shell.\\$ ");
	execl("/bin/sh", "/bin/sh", "-i", NULL);
	fprintf(stderr, "OK: exec of /bin/sh failed.\n");
#endif

	if (argc != 3)
		die("Usage: %s infile outfile\n", *argv);
	
	infilename = argv[1];
	outfilename = argv[2];

	if (!(infile = fopen(infilename, "r")))
		die("Opening: infile %s: %s\n", infilename, strerror(errno));

	if (!(outfile = fopen(outfilename, "w")))
		die("Opening: outfile %s: %s\n", outfilename, strerror(errno));

	while ((c = fgetc(infile)) != EOF) {
		bytes++;

		if (isdigit(c)) {
			c = '@';
			modified++;
		}

		if (fputc(c, outfile) == EOF)
			die("Writing to outfile %s: %s\n", outfilename,
				strerror(errno));
	}

	if (!feof(infile))
		die("Reading from infile %s: %s\n", infilename,
			strerror(errno));

	if (fclose(infile) == EOF)
		die("Closing input file %s: %s\n", infilename,
			strerror(errno));

	if (fclose(outfile) == EOF)
		die("Closing/flushing output file %s: %s\n", outfilename,
			strerror(errno));

	fprintf(stderr, "Data copied. %d out of %d bytes modified.\n",
		modified, bytes);
	return 0;
}